Department of Pharmacy, JES's SND College of Pharmacy, Babulgaon (Yeola), India.
An autoimmune condition with a complex pathophysiology and complicated etiology is rheumatoid arthritis (RA). Repeated monotherapy in RA is often linked to severe side effects, medication resistance, and insufficient efficacy. As a result, combination therapy is now more common in clinical practice. Low selectivity to arthritic joints, short half-lives, and different pharmacokinetics across linked medications are some of the challenges that conventional combination therapy faces. A unique chance to create a sophisticated combination treatment for RA is presented by emerging nanotechnology. First, it enables the co-administration of several medications with improved physicochemical characteristics, regulated release profiles, and targeted delivery capabilities. Second, it makes it possible to create therapeutic nanomaterials, which broadens combination regimens to incorporate multipurpose nanomedicines. Last but not least, it makes it easier to create multimodal nanoplatforms that combine imaging, phototherapy, and sonodynamic therapy. As a result, nanotechnology presents a viable way to overcome the present obstacle in the diagnosis and treatment of RA. The justification, benefits, and most recent developments in nano-enabled combination therapy for RA are outlined in this paper. Drug-drug interactions, safety issues, and the possibility of clinical translation are also covered. It also offers design advice and a forecast for upcoming advancements in combination therapy enabled by nanotechnology. In order to facilitate the seamless transfer of research findings from the lab to clinical practice, this study aims to fully comprehend the mechanics behind combination therapy for RA and unleash the full potential of nanotechnology.
Rheumatoid arthritis (RA) is an autoimmune illness of the system that causes inflammation and extra-articular involvement. It usually begins in tiny peripheral joints, is symmetrical, and if treatment is not received, proceeds to affect proximal joints. Prolonged inflammation of the joints causes cartilage loss and bone erosion, ultimately resulting in joint degeneration. When the symptoms of RA appear for less than six months, it is referred to as early RA, and when they appear for more than six months, it is referred to as established RA. If left untreated, RA progresses and increases in morbidity and mortality. Women are more likely than men to have this illness, and older people are also more likely to have it the disease's effects include systemic joint inflammation, persistent synovitis, tissue damage from cytokine release, and inflammation brought on by an imbalance in the autoimmune cells. Tissue damage will result from the autoimmune antibodies. In adults, rheumatoid arthritis affects 1% of the population. When it comes to the primary cause of comprehensive frailty, this illness ranks 42nd. Deaths from rheumatoid arthritis associated with heart conditions and lung problems are 10–20% and 60–80%, respectively. Presently, there is a comparable occurrence in rheumatoid arthritis patients that is linked to an elevated risk of cancer either during or after treatment. The word "rheumatism" originates from a 2500-year-old Greek phrase that means "flowing current," signifying the movement of the body's afflicted joints as a whole.
The wrists, hands, or feet are the typical locations for RA signs and symptoms, which might include:
Figure 1: Bone joint differentiation of normal and Rheumatoid arthritis joint
The condition results in tissue damage, inflammation, persistent synovitis, and inflammatory degradation of the spine and related joints. These factors finally cause severe functional decline, an increased risk of accidents, and early mortality. Furthermore, extra-articular symptoms such as pulmonary, cardiac, and renal involvement, vasculitis, lymphoproliferative diseases, and infections are all contributing factors to the higher death rate. In relation to heart disorders and pulmonary problems, the death rates from RA are roughly 10–20% and 60–80%, respectively. The primary cytology of comprehensive frailty ranked this illness forty-second. These days, individuals with RA have a higher chance of developing cancer. The complex interplay of immune modulators is the cause of the joint dysfunction. Within the rheumatoid arthritis progression, a few cells similar to B cells, T cells, and synoviocytes (macrophages) play a significant part in the development of immune responses. B cells are going to wing the inflammatory process by generating autoantibodies such as anti-cipitinated protein antibody and rheumatoid factor. T cells are going to activate. macrophages, which will in fact result in the excessive synthesis of inflammatory cytokines such as IL-1?, IL-6, and TNF-?. The amplified fabrication of T and B cells will result in the fabrication of cytokines and chemokines leads to the raise in the T cell, B cell, and macrophage interface. Inflammatory cytokines will persuade the cells of synovial to discharge tissue mortifying matrix metalloproteases. Bone erosion occurs due to the progress of osteoclast by TNF-?.
2. Etiology
Figure 2: Some factors responsible for RA
It is uncertain what causes rheumatoid arthritis to occur. Perhaps there has been a change in reaction to a host that is genetically vulnerable to an agent that spreads infection. . The causative agents may include Mycoplasma, cytomegalovirus, Epstein Barr virus, rubella virus, and parvovirus. The distinctive spreading of an infectious agent that causes chronic inflammatory arthritis is unknown. The relevant factors influencing rheumatoid arthritis a. Genetic and environmental factors b. Smoking c. Human microbiome.
A combination of genetic and environmental variables contribute to rheumatoid arthritis. The genetic effect ranges from 30% to 60% due to numerous hereditary research. The primary hereditary component "Shared epitope" is associated with rheumatoid arthritis. which the DRB1 allele possesses. The threefold rise in rheumatoid arthritis cases arthritis is associated with the existence of a common epitope.
b. Smoking:
The primary risk factor for the emergence of numerous chronic illnesses is smoking.
A few cohorts claim that the risk for theRheumatoid arthritis development is more common in people with an ACPA positive who drink coffee.With those who have a relative risk factor of 2.06, more than four cups of coffee every day. An Swedish cohort reports that exposure at work The risk factor for men is exposure to mineral oil. The People in Sweden who work as professionals in mineral oil reserves demonstrated a 57% rise.when rheumatoid arthritis strikes. People who test positive for APCA will develop rheumatoid arthritis if exposed to silica at work. Additional factors that have been linked to an increased risk of rheumatoid arthritis include a lower intake of vitamin D and antioxidants and a higher diet of sugar, sodium, red meats, proteins, and iron.
c. Human microbiome:
The human microbiome: Since rheumatoid arthritis is characterized by an extreme expansion of microbes and a lack of bacteria or other organisms, the transition from a symbiotic to a dysbiotic microbiome is a contributing risk factor for the disease's development. Deviations in innate and adaptive immunity may result from this.
3. Pathophysiology Of Ra
While there is still much to learn about the pathophysiological mechanisms behind RA, a number of theories have been proposed. It has been shown that immunological mechanisms, known as the "pre-RA phase," can take place years before signs of joint inflammation become apparent. As in the cases of immunoglobulin G (IgG), type 2 collagen, and vimentin, interactions between environmental influences and epigenetic alterations on the chromosomal structure can result in changed self-antigens. Peptide arginine deiminases can perform a post-translational alteration known as citrullination on these proteins containing arginine residues, converting them to citrulline. Furthermore, cytokine release that may result in joint inflammation and modified self-antigens can be triggered by joint illnesses such as synovial hyperplasia or synovial infections. The immune system can no longer identify citrullinated proteins (vimentin, type II collagen, histones, fibrin, fibronectin, Epstein-Barr nuclear antigen 1, ?-enolase) as self-structures because of the susceptibility genes HLA-DR1 and HLA-DR4. Antigen-presenting cells (APCs) are activated dendritic cells that take up antigens in order to start an immune response. The entire complex moves to the lymph node, where CD4+ helper T cell activation occurs. Moreover, B cells in the germinal center of the lymph node are stimulated by T cells in a reciprocal and sequential signaling mechanism known as stimulation. The interaction of CD28 with CD80/86 is one instance of costimulation. At this stage, B cells experience class-switch recombination or somatic hypermutation, which leads to the proliferation and differentiation of intro plasma cells, which in turn manufacture autoantibodies based on the precursor cells' receptors. Autoantibodies are proteins generated by an immune system that has lost the ability to distinguish between self and non-self-structures, resulting in the unintentional targeting of own tissues and organs. The most researched autoantibodies linked to RA include RF and ACPA. The constant region, or Fc component of IgG, is the target of RF, an IgM antibody that has an 85% testing specificity in RA patients. Together with complement protein and IgG, it also forms an immunological complex that can move through synovial fluid. On the other hand, citrullinated proteins are the target of ACPA, which is more specific for RA. Following their contacts of binding, immune complexes are created that accumulate in the synovial fluid. Figure 4 summarizes every aspect of an immune response during the pre-RA period. Air pollution, which is defined as a mixture of gases (nitrates, ozone, sulfur dioxide, and carbon monoxide) and suspended particulate materials (PM) of different sizes, has recently drawn more attention in the field of respiratory anatomy (RA). Numerous man-made and natural processes, including as farming, the burning of fossil fuels, the chemical industry, the use of solvents, volcanic eruptions, wind-blown dust, emissions from plants, etc., can discharge pollutants into the atmosphere. The majority of research on the clinical effects of air pollution focuses on respiratory conditions. It has been noted that ozone harms the alveoli, a vital component of the respiratory system that filters carbon dioxide and oxygen. By reacting with various enzymes, pollutants can also cause secondary damage to lung tissue, such as infection or inflammation of the lungs. It has been shown through three significant epidemiological studies carried out in the US, Canada, and Sweden that there is a connection between air pollution and the pathophysiology of RA.Regression models were used in a study by Alsaber et al. (2020) to look into the relationships between air pollution and RA activity. It has been found that nitrates and sulfur dioxide provide significant risks for the development of RA. One of the most recent research studies to be published examined a potential relationship between air pollution in the Verona area and the evolution of RA in 888 patients. The study found that high levels of CRP are associated with the severity of RA illness and its reactivations as a result of a poor response to biological therapies.
Figure 3: Immunological processes in the pre-RA phase. ACPA, anti-citrullinated protein antibodies; APC, antigen-presenting cells; RF, rheumatoid factor.
Air pollution may have a role in the etiology of RA through a few different molecular pathways. Inhaled PM can produce free reactive oxygen species (ROS) that can trigger nuclear factor kappa B (NF-KB), which in turn triggers T helper cell type 1 (Th1) to release interleukin-1 (IL-1) and interleukin-6 (IL-6), as well as tumor necrosis factor alpha (TNF-?). These cytokines encourage resting monocytes to develop into mature dendritic cells, which in turn provide auto-antigens to self-reactive T lymphocytes, triggering the latter to migrate to target tissues and exacerbate joint erosion and inflammation. Furthermore, ROS contribute in the citrullination of arginine amino acid residues into citrullinated peptides, hence promoting systemic inflammation and chronic lung disease. Biochemical reactions produce ACPAs, which bind to cellular Fc receptors and activate complement, inducing an immune response that causes bone degradation and inflammation in the joints. Decreased UVB exposure leads to a decrease in the skin's production of 1,25-dihydroxyvitamin D3, which acts as an immunomodulator by activating the vitamin D receptor (VDR). RA may occur from suboptimal immunomodulatory functioning as a result . The gut microbiota, the most heavily colonized bacterial population in the human body, is another crucial component that plays a significant role in the pathophysiology of RA.
The etiology of RA is also associated with intestinal dysbiosis, which triggers specific autoimmune pathways and mechanisms, including molecular mimicry, altered intestinal permeability, stimulation of APC through activation of toll-like receptors (TLRs) or nod-like receptors (NLRs), promotion of T cell differentiation, and amplification of mucosal inflammation through specific pathways. It has been established that gut microbes affect immunological, metabolic, and neurobehavioral traits. RA patients' gut microbiota composition differed significantly from that of healthy controls, with several bacterial communities showing an increase or decrease. Proximal intestinal immunomodulatory cells (PICs) are particular gut cells that have the ability to influence the development of RA. The gastrointestinal microbiota can influence this process. 16S rRNA sequencing and metagenomic shotgun sequencing have shown quantifiable changes in certain bacteria in RA patients in a number of case-control investigations. The studies' findings showed that RA patients had higher concentrations of Prevotella copri, Collinsella, and Lactobacillus salivarius, although their levels of Bacteroides, Faecalibacterium, Veillonella, and Haemophilus were reduced.
Figure 4: illustrates the processes by which gut microbiota and air pollutants contribute to the development of RA.
The disease steadily worsens over time, however the subtle start of symptoms is a common characteristic of RA. The immune activities that occur in the synovium and synovial fluid have been documented, but the cause of RA symptoms is still unknown. Tumor necrosis factor alpha (TNF-?), interleukin-1 (IL-1), and interleukin-6 (IL-6) are released by synovial macrophages and are linked to inflammatory processes, the activation of osteoclasts, and the stimulation of fibroblast-like synoviocytes (FLS). Bone degradation is caused by increased osteoclast maturation and activity. Activated FLS cells are specialized cells that have the ability to create MMP (matrix metalloproteinase). Proteases are secreted by cartilage as a feedback mechanism, and MMP can cause cartilage breakdown. FLS has the ability to move between joints, resulting in symmetrical RA patterns. Additionally, FLS increases the production of receptor activator of nuclear factor-kB ligand (RANKL), which enables T cells to attach to proteins on the surface of osteoclasts. This, in turn, increases the activity of osteoclasts, which further rcontributes to bone degradation. Through RANKL expression stimulation and the production of interleukin 17 (IL-17), CD4+ T cells contribute significantly to the activation of synovial macrophages and FLS, hence promoting inflammation, bone erosion, and cartilage degradation. By the use of autoantibodies and cytokines, plasma cells also encourage inflammation. Neutrophils have been found in synovial fluid, and they release reactive oxygen species (ROS) and proteases that can erode bone and degrade cartilage. Additionally, immune complexes, including antibodies that attach to one another, induce inflammation, and over-activate the complement system, have been found in synovial fluid. The act of creating new blood vessels from preexisting ones is known as angiogenesis, and it also happens in RA. Despite being helpful in many physiological processes, it is crucial in RA because increased vascular permeability and the expression of adhesion molecules (vascular adhesion molecule 1) allow immune cells to travel into the joints. Additionally, RA patients' synovium contains the proangiogenic factor vascular endothelial growth factor (VEGF), which plays a strong role in bone loss by stimulating osteoclast generation. Figure 5: summarizes the pathophysiological pathways that result in the onset of RA symptoms. In addition, a multitude of signaling molecules with distinct roles in inflammatory processes underpin the intricacy of this illness. Small signaling proteins called Janus kinases (JAKs) have pathological significance because they can serve as molecular targets for a variety of therapeutic treatments. Therefore, more study is required to fully understand the pathogenic pathways and to develop future treatments with excellent safety and efficacy profiles.
Figure 5: Pathological mechanisms in RA. IL, interleukin; FLS, fibroblast-like synoviocytes; MMP, matrix metalloproteinase; RANKL, receptor activator of nuclear factor-kB ligand; ROS, reactive oxygen species.
4. Treatment
To relieve pain and swelling fast and to gain control of the inflammation, glucocorticoids (GC) are used widely in acute disease flares either orally or as intraarticular injections. Oral GC is for short-term use (up to 3–4 month) only and should be tapered to prevent side effects as soon as possible. To control inflammation in the long run, Disease Modifying Anti-Rheumatic Drugs (DMARD) to spare GC are needed. Nowadays, there are a bunch of opportunities that can be challenges or chances. The treatment of patients with RA aims to relieve pain and to control inflammation, and the final goal is to achieve remission or at least low disease activity for all patients. In this context, the European League Against Rheumatism (EULAR) has composed 10 international recommendations on how to treat patients. An algorithm based on the EULAR recommendations is shown in Figure 6. In 2010, an international committee developed the treat-to-target (T2T) initiative. The centerpiece of this initiative is the shared decision-making and regular patient revaluation that targets remission or at least low disease activity (LDA).
4.1 Treatment Guidelines: Conventional Synthetic DMARD (Csdmard)
As soon as the diagnosis of rheumatoid arthritis is made, a treatment with a csDMARD should be started. A controlled comparison between csDMARDs for the first-line therapy does not exist; however, within this group, methotrexate should be the first choice because, for this drug, most clinical experience exists in monotherapy and as a combination partner with other DMARD. Methotrexate is usually started at a dose of 15 mg/week and can be stepwise increased up to 25 mg/week. The combination with glucocorticoids is recommende. Due to the decreased bioavailability, a subcutaneous way of administration is recommended. The induction of remission with a combination of conventional synthetic DMARDs at this stage is not superior to methotrexate monotherapy; however, these combinations are associated with more adverse events and a higher rate of drug discontinuation. Patients with a higher baseline disease activity and Rheumatoid factor (RF)-positive patients have an increased risk of methotrexate (MTX) failure due to inefficacy.
If MTX cannot be used, e.g., due to intolerance or contraindications, leflunomide (20 mg/week) or sulfasalazine (2 g/day) should be started. In a placebo-controlled randomized controlled trial (RCT), both substances showed a similar efficacy.
If by week 12 after the start of MTX therapy no adequate response is achieved or no remission is reached with optimum doses after 24 weeks, the therapy should be adjusted. To find the best individual treatment strategy, patients should be categorized using prognostic markers. Poor prognostic markers such as the presence of autoantibodies, early joint damage, and high disease activity are associated with rapid disease progression; therefore, a biologic DMARD or a targeted synthetic DMARD should be added at this stage. In the absence of poor prognostic markers and with moderate disease activity, a second csDMARD should be added to the therapy.
Figure 6: Algorithm adapted from the 2016 European League Against Rheumatism (EULAR) recommendationson rheumatoid arthritis (RA) management. bDMARD, biological; bsDMARD, biosimilar DMARDs; csDMARDs, conventional synthetic DMARDs; DMARDs disease modifying amtirheumatic drug; IL, Interleukin; MTX, methotrexate; TNF, tumor necrosis factor; tsDMARDs, targeted synthetic DMARDS.
4.2 limitations of current treatment
The primary goals in the treatment of RA are to control inflammation and slow or stop disease progression. Initial therapeutic approaches relied on disease-modifying anti-rheumatic drugs, or DMARDS, such as MTX and sulphasalazine. These oral drugs work primarily to suppress the immune system and, while effective in this regard, the suppression of the immune system leads to an increased risk of infections. These drugs are also associated with side effects including nausea, abdominal pain, and serious lung and liver toxicities. Further, because these drugs often take an average of 6–12 weeks to take effect, rheumatologists may also couple them with over-the-counter pain medications or non-steroidal anti-inflammatory drugs to treat the pain and inflammation. Despite these shortcomings, DMARDS are still considered first-line therapies. The development of monoclonal antibodies and biologics represented a significant advance in RA treatment. Biologic therapies involve the use of antibodies or other proteins produced by living organisms to treat diseases. In the majority of people with arthritis, the tumor necrosis factor, or TNF, protein is present in the blood and joints in excessive amounts, thereby increasing inflammation, along with pain and swelling. Biologic therapies have been developed to address this overproduction of TNF by disrupting communication between the body’s immune cells. Thus, they block the production of TNF or are designed to attach to and destroy the body’s immune B-cells, which play a part in the pain and swelling caused by arthritis. Anti-TNFs are currently the standard of care for first- and second-line biologic therapies for RA patients who have an inadequate response to DMARDS. Since anti-TNF drugs function through a suppression of the immune system, they also lead to a significant increase in the risk of infections. In addition, all approved anti-TNFs need to be delivered by injection or intravenously, which is inconvenient and painful for some patients, and in some cases self-injection can be particularly difficult for patients who suffer joint pain and damage from RA.Not all patients achieve sufficient clinical response or maintain clinical response to anti-TNFs over time, resulting in a need to switch or cycle to a new therapy to control their disease. Approximately one-third of RA patients do not adequately respond to anti-TNFs. In addition, anti-TNFs are associated with low rates of disease remission and the response to these agents is not typically durable. In more than 30% of this population, alternative treatment approaches are needed. A significant number of patients treated with an anti-TNF will be cycled to their second and third anti-TNF within 24 months of anti-TNF therapy initiation. Therapeutic cycling is a serious issue for patients because the efficacy of each successive drug is not known typically for several months, which contributes to progression of disease and continued irreversible structural joint damage. For RA patients who fail or for whom anti-TNFs are contra-indicated, biologics with distinct mechanism and the oral agent JAK inhibitors provide alternative treatment opportunities.
4.3 New Treatments for Rheumatoid Arthritis
The pharmacological therapy of RA leads to several complications. There are reported adverse effects on the gastrointestinal tract, hepatic, cardiac and renal function because of prolonged usage of DMARDs, NSAIDs (non-steroidal anti-inflammatory drugs) and glucocorticoids. It is necessary to surmount the limitations of these therapeutic agents while curing RA. Over the limitation of current treatment of RA there are various new treatment of RA.
Some are as
4.3.1 Nanoparticles based delivery system
To overcome the disadvantages of conventional RA drugs, several targeting nanodelivery systems are being developed to control drug release and prolong drug circulation in the blood while decreasing systemic toxicity.
Nanoparticles, liposomes and micelles are commonly used in medical applications for drug delivery, diagnostics and imaging, because of their good biodegradability and sustainability (Figure 7). These materials can stabilize drugs, control drug release and enhance drug accumulation at inflamed sites.
Figure 7: Nanoparticles commonly used in targeted delivery systems. PLGA, poly (lactic-co-glycolic acid)
1.liposomes
Figure 8: Structure of liposomes
Liposomes consist of phospholipids and cholesterol, which form a lipid bilayer with an aqueous core. Their particle sizes are usually in the range of 25 nm to 2.5 ?m Liposomes can encapsulate both hydrophobic and hydrophilic drugs, and they have good biocompatibility and biodegradability. However, the ability of liposomes to encapsulate hydrophobic drugs is not ideal, and drugs can easily leak out. Although traditional liposomes are rapidly cleared by the reticuloendothelial system, modifying liposomes with polyethylene glycol (PEG) effectively decreases the adsorption of plasma proteins and subsequent clearance by the reticuloendothelial system, thus prolonging the circulation of drugs in the blood and improving their distribution in inflamed joints. Intravenous administration of dexamethasone-loaded polymerized stealth liposomes to arthritic rats has been found to significantly prolong drug circulation in the blood and to enhance drug accumulation in inflamed joints. This treatment significantly decreases the levels of TNF-? and IL-1? at lesion sites as well as the degree of joint swelling, thus indicating inhibition of RA progression. The peptide ART-2 (CKPFDRALC) shows preferential homing to arthritic joints of rats and strong binding to endothelial cells. To improve the targeting efficiency of liposomes to inflamed joints, one study has designed liposomes modified with ART-2 peptide. These dexamethasone-loaded liposomes with ART-2 modification accumulate in inflamed joints to a greater extent than dexamethasone-loaded liposomes without ART-2 modification, and relieve RA more efficiently. Beyond hydrophobic drugs, liposomes can also be used to efficiently encapsulate hydrophilic drugs. Hydrophilic drugs can be encapsulated within the aqueous core of liposomes. Liposomes loaded with tofacitinib citrate, a water-soluble anti-inflammatory drug, have been found to be selectively internalized by inflammatory cells in a rat model of arthritis and to accumulate in arthritic paws. This method of tofacitinib citrate delivery significantly improves its therapeutic efficacy, downregulates inflammatory cytokines in joint tissues and relieves RA symptoms. In another study, PEGylated liposomes loaded with water-soluble berberine have been found to accumulate selectively in inflamed joints of rats with adjuvant-induced arthritis (AIA). Berberine potently activates miR-23a, thus downregulating inflammatory kinases such as ASK1 and GSK-3?, as well as mediators of Wnt1 signaling, and ultimately mitigating bone erosion. The safety
and efficacy of liposomal bupivacaine has been confirmed in surgery; however, its pharmacokinetic parameters and safety in a Chinese population have not been evaluated. A phase I study has confirmed that liposomal bupivacain is well tolerated and safe among individuals of Chinese descent.
II. Gold nanoparticles
Gold nanoparticles (AuNPs), with particle sizes ranging from 1 to 100 nm, are widely used in diagnostics, therapy and biological imaging. AuNPs have excellent stability and biocompatibility, customizable shapes and dimensions, easily functionalized surfaces, high drug loading capacity and low toxicity. However, AuNPs tend to accumulate in the kidneys, liver and spleen after entering the body, thus potentially leading to incomplete metabolism in the body. AuNPs have strong affinity to thiol and amine groups, and therefore can bind targeting agents possessing these groups. In addition, AuNPs have good binding ability toward vascular endothelial growth factor and show natural antiangiogenic effects in inflamed synovium. Intra-articular injection of AuNPs of various dimensions into CIA mice has indicated clear antioxidant action, by significantly increasing catalase activity without causing any adverse effects on hematological indices. AuNPs of 50?nm, compared with 13 nm, have shown superior effects in inhibiting synovial angiogenesis, and have achieved better antioxidant and therapeutic effects in early stages of arthritis. In another study, an MTX delivery system consisting of gold nanorods with a mesoporous silica shell (FAGMs) has been used for controlled release of MTX. The release rate of MTX from FAGMs in vitro markedly increases under 808 nm laser irradiation, thus achieving superior effects in inhibiting RA progression in AIA rats while decreasing the systemic toxicity of MTX, compared with free MTX. These findings suggest that FAGMs may hold promise in the treatment of RA. In addition, clinical trials have tested the coupling of human proinsulin peptide (C19-A3) with AuNPs (C19-A3-AuNPs) for the treatment of type 1 diabetes. In a phase I clinical trial, the safety of intradermal administration of C19-A3-AuNP through microneedles has been explored. Patients with type 1 diabetes have shown good tolerance to C19-A3-AuNPs with no signs of systemic allergy.
III. Polymeric micelles
Polymeric micelles are core-shell structures with a particle size of 10–100 nm that form through self-assembly of amphiphilic block copolymers in aqueous solutions. Polymeric micelles can effectively avoid clearance by the kidneys and reticuloendothelial system, and they can target inflamed tissues through the ELVIS effect. Micelles form when the polymer concentration in the solution exceeds the critical micellar concentration, and they dissociate into monomers when the polymer concentration is below the critical micellar concentration. Micelles with lower critical micellar concentrations are therefore more stable in circulation. Copolymeric micelles loaded with indomethacin, a non-steroidal anti-inflammatory drug that can effectively control inflammation, have been found to significantly relieve inflammatory symptoms and decrease the arthritic index and paw diameter in AIA rats. Similarly, micelles loaded with dexamethasone palmitate have been found to accumulate at inflamed sites and to decrease joint inflammation. In another study, maltodextrin-?-tocopherol nano-micelles loaded with tacrolimus (TAC@MD-?-TOC) have been prepared for RA therapy. The micelles have been found to show stronger anti-rheumatic effects than the free drug. In vitro and in vivo experiments have demonstrated that TAC@MD-?-TOC is more effective than the free drug in promoting the viability of Vero cells and decreasing the levels of IL-6 and TNF-? in the serum and synovial fluid Monotherapy with MTX usually leads to irreversible joint injury because of its slow onset and long duration. MicroRNA-124 (miR-124) has shown direct bone protective effects against RA. Hybrid micelles containing both MTX conjugated polymer and miR-124 have been found to target and accumulate in the inflamed joints of AIA rats, and effectively enhance the synergistic effects of MTX and miR-124. Wang et al. have used polymeric micelles to co-deliver Dex and siRNA against p65, a member of the NF-?B family, to arthritis sites to treat RA. These co-loaded micelles have been found to efficiently inhibit NF-?B signaling in macrophages in CIA mice and to cause activated macrophages in arthritic synovial membranes to revert to an anti-inflammatory state. In the treatment of RA, micelles co-loaded with Dex and p65 siRNA have shown better efficiency than free Dex or naked siRNA. In addition, a phase II study on the efficacy and safety of docetaxel-PM for treating recurrent or metastatic squamous cell carcinoma of the head and neck was conducted in 2015, and this docetaxel-PM is now on the market.
IV. PLGA nanoparticles
Poly (lactic-co-glycolic acid) (PLGA) is a non-toxic, biodegradable polymer often used as a drug delivery carrier. PLGA nanoparticles can regulate drug release, and their surfaces can be easily modified. They are commonly used to protect biological agents, such as proteins and nucleic acids, against rapid metabolism and clearance in vivo. The drug release from PLGA particles depends on the molecular weight of the polymer. Polymers with higher molecular weights have longer polymer chains, thus resulting in longer degradation times and slower drug release rates. For example, loading of apremilast, a small-molecule drug designed for oral delivery, into PLGA nanoparticles significantly prolongs its half-life and mean residence time in vivo . Luteinium-177, a radionuclide with a half-life of 6.71 d, can be used for radiation treatment of joints with advanced arthritis, owing to its ? maximum emission energy (0.497 MeV, 78%). Hyaluronic acid (HA) is a polymer that specifically binds CD44 overexpressed on inflamed synovial cells. In one study, PLGA modified with Luteinium-177 and HA has been used for encapsulating MTX (177Lu-DOTA-HA-PLGA(MTX)). The 177Lu-DOTA-HA-PLGA(MTX) nanoparticles strongly bind, and are efficiently internalized by, inflamed synovial cells]. In addition, encapsulating dexamethasone palmitate in PLGA-PEG nanoparticles has been found to improve the drug’s pharmacokinetic profile, and decrease its tendency to damage cells and aggregate in the liver, kidneys and lungs. Bruton’s tyrosine kinase (BTK) in macrophages and B cells is an important target in RA therapy. However, high dosages of BTK inhibitors are needed for effective BTK inhibition, thus limiting their clinical application. Zhao et al. have developed cationic lipid-assisted PEG-b-PLGA nanoparticles (CLAN) loaded with BTK siRNA (CLANsiBTK). In the CIA mouse model, CLANsiBTK has been found to significantly alleviate arthritis symptoms, downregulate the expression of inflammatory cytokines (TNF-?, IL-1? and IFN-?) and decrease damage to the paw joints.
V. Solid lipid nanoparticles (SLNs)
SLNs, a lipid-based drug delivery system with a particle size of 10–1000 nm, specifically target inflamed tissues and enable controlled drug release. SLNs show low immunogenicity in the human body and can easily infiltrate biological tissues while carrying large amounts of lipophilic compounds. However, the ability of SLNs to encapsulate hydrophilic drugs is poor. Moreover, changes in the drug release curve, polymorphic transformation and particle aggregation occur during storage. Zhang et al. have loaded ?-sitosterol into SLNs to improve its water solubility and bioavailability in AIA rats. The developed nanoparticles (?-sitosterol-SLNs) have been found to exhibit good anti-arthritic effects by inhibiting NF-?B and activating the heme oxygenase-1/NF-erythroid 2-associated factor 2 pathway. To improve the targeting of inflamed tissue, prednisolone-loaded SLNs coated with HA have been prepared; these SLNs have been found to accumulate in the inflamed joints of CIA mice and to decrease joint swelling, bone erosion and levels of inflammatory cytokines.
VI. Chitosan nanoparticles
Chitosan, a polysaccharide that arises through the deacetylation of chitin, is widely used in the preparation of microparticles and nanoparticles. Chitosan nanoparticles have good biodegradability, low immunogenicity and high cell permeability, and therefore are suitable nanocarriers for targeted drug delivery. For example, chitosan nanoparticles can improve the efficacy of the anti-inflammatory drug embelin, which is poorly absorbed in the body, and is rapidly metabolized and cleared. Loading embelin into chitosan nanoparticles downregulates malondialdehyde and nitroxide, as well as TNF-?, IL-6 and IL-1? in the serum in AIA rats, while decreasing oxidative stress. In a study in CIA rats, eugenol loading into chitosan nanoparticles has been found to significantly improve the drug’s ability to decrease the expression of monocyte chemoattractant protein-1 and transforming growth factor-?, and to alleviate joint synovial hyperplasia and cartilage injury. Similarly, loading zinc gluconate into chitosan nanoparticles has been found to improve the compound’s ability to inhibit the infiltration of inflammatory cells in ankle joints; downregulate TNF-?, IL-6 and inducible nitric oxide synthase; and upregulate SOD1.
VII. Albumin nanoparticles
Albumin is the most abundant protein in the plasma, accounting for approximately 60% of the total protein in the blood. It is considered an ideal candidate for drug delivery because of its strong ability to bind hydrophobic and hydrophilic drugs, relatively long half-life in the blood (19 days), biodegradability and lack of immunogenicity. Albumin, which has a molecular weight of 66.5 kDa, can be obtained from various sources, such as egg white (ovalbumin), bovine serum (BSA) or human serum (HSA). The nanoparticles can prolong the circulation in the blood by adsorbing albumin. For example, coating albumin on the surfaces of liposomes or embedding it directly in phospholipids of liposomes enables the nanostructures to evade phagocytosis, thus prolonging their circulation. In a study in AIA rats, loading carvacrol into BSA nanoparticles has been found to significantly improve the anti-inflammatory agent’s ability to mitigate swelling and decrease release of the inflammatory cytokines NO and IL-17 in arthritic rats. To improve the targeting of BSA nanoparticles, Gong et al. have prepared palmitic acid modified BSA nanoparticles (PAB NPs) and loaded them with celastrol. The PAB NPs efficiently bind scavenger receptor-A (SR-A) and elicit 9–10 times more macrophages than normal BSA NPs. PAB NPs have been found to deliver the anti-inflammatory drug celastrol to inflamed tissues more effectively than BSA NPs, and to alleviate RA symptoms at lower doses. Loading MTX into HSA nanoparticles labeled with chlorin e6 has been found to increase the drug’s accumulation and retention in inflamed joints of CIA rats; the encapsulated drug slows RA progression as effectively as a 50% higher dose of free drug. In a study in AIA rats, treatment with prednisolone and curcumin loaded into HSA nanoparticles has led to lower levels of pro-inflammatory cytokines in activated macrophages, higher levels of the anti-inflammatory cytokine IL-10, greater drug accumulation in inflamed joints and stronger therapeutic efficacy than nanoparticles loaded with single drugs or free drugs alone or a mixture of two drugs. Abraxane (paclitaxel combined with albumin) was approved by the FDA in 2005. In 2021, the FDA approved Fyarro (sirolimus albumin-bound nanoparticles, nab-sirolimus, ABI-009) to be marketed for intravenous infusion in the treatment of locally advanced unresectable or metastatic malignant perivascular epithelioid cell tumors.
All the above studies used exogenous albumin to prepare nanoparticles in vitro. However, after nanoparticles enter the body, they can cause immunogenic reactions. Therefore, some researchers have attempted to use the endogenous albumin in the body to prepare albumin-bound nanoparticles for targeting therapy. The albumin-binding domain (ABD, 46 amino acids) has been reported to have strong affinity for serum albumin. The ABD035 variant has shown superior affinity toward albumin from various sources (such as human, mouse, rat, cow and monkey albumin). Zhang et al. have designed a redox-responsive paclitaxel micelle system modified by the ABD035 peptide. After intravenous injection, the micellar system has been found to combine with endogenous albumin in blood, then deliver paclitaxel to tumor cells via gp60 and SPARC receptors. Inflammatory tissue has similar characteristics to tumor tissue, such as abundant albumin receptors and incomplete vascular structure. Therefore, developing nanoparticles that bind endogenous albumin may serve as a favorable strategy for targeting RA.
VIII. Biomimetic nanoparticles
Biomimetic nanoparticles have attracted particular attention in recent years because of their ability to evade clearance by the reticuloendothelial system. Biomembranes are usually extracted through the following method. Cells are placed in hypotonic liquid for cell disruption and lysis, then purified and collected by discontinuous gradient centrifugation at 4 °C. Protease inhibitor is added throughout the entire extraction process to protect protein activity. Nanoplatforms are prepared by encapsulating nanoparticles into cell membranes extracted from red blood cells, macrophages, neutrophils or platelets through co-extrusion, extrusion/sonication, freeze-thaw/sonication, extrusion/sonication and other methods . These nanoplatforms have shown excellent biocompatibility, effective drug delivery, prolonged circulation times in the blood and minimal adverse immune responses . For example, spherical, prolate-spheroidal and oblate-spheroidal PLGA nanoparticles coated with erythrocyte membrane effectively evade clearance by macrophages. Encapsulation of hydroxychloroquine-loaded nanoparticles in membranes from umbilical vein endothelial cells expressing TNF-associated apoptosis-inducing ligand has generated nanoparticles for the delivery of hydroxychloroquine to inflamed joints in CIA mice while also inducing M1 macrophage apoptosis by upregulating death receptor-5, thus effectively inhibiting RA progression. In CIA mice, coating nanoparticles with neutrophil membranes and then administering these nanostructures together with immunoregulatory molecules has been found to promote tissue repair, downregulate pro-inflammatory cytokines and inhibit synovitis.
IX. Injectable hydrogels
Hydrogels are highly hydrated three-dimensional networks of hydrophilic polymers, whose bionic structure is similar to that of the extracellular matrix of natural biological tissues and has good biocompatibility. Injectable hydrogels are more comfortable, and elicit less pain and fewer adverse effects, than non-injectable hydrogels. Favorable injectable hydrogels cannot easily be obtained by using a single material. Incorporating nanofiller into a polymer matrix can achieve desirable injectable gels with high biocompatibility and biodegradability, more easily modifiable properties, and better ability to deliver hydrophilic or hydrophobic macromolecules in a sustained manner.
Figure 9: Hydrogels in RA
Injectable hydrogels with loosely interconnected polymer chains have shown higher burst release and more rapid drug clearance. Wang et al. have developed a temperature-sensitive hydrogel (DLTH) based on chitosan-glycerol-borax for intra-articular delivery of dexamethasone . In the CIA mouse model, intra-articular injection of DLTH loaded with dexamethasone has shown good anti-inflammatory and analgesic effects. Similarly, in situ hydrogels have also been designed to co-deliver indomethacin, methotrexate and MMP-9 siRNA for synergistic and comprehensive treatment of RA. These in situ hydrogels significantly down-regulate the expression of inflammatory factors (TNF-?, IL-6) and MMP-9 in plasma and knee joint fluid after intra-articular injection.
4.3.2 Gene therapy
To overcome the limitations and difficulties of the present treatments, genetic therapies for RA offer the possibility of delivery of the therapeutic gene product to the disease site and, thus, prevent side effects by systemic injections or infusion, while enhancing efficacy and achieving local long-term expression, with endogenous production of high concentrations of the therapeutic agent. The overall goal for the treatment of patients with RA should not merely be alleviating the pain, but also achieving remission or at least low disease activity for all patients and preventing irreversible damage to the diseased joints. Since most, if not all, of the forms of RA result in the inflammation of the joint, and thus, share the process of inflammation, a gene therapy approach for RA, aiming either at inhibiting proinflammatory cytokines and/or overexpressing anti-inflammatory cytokines, could be promising. In this context, and given the fact that the overproduction of inflammatory cytokines by fibroblast-like synoviocytes (FLSs) is believed to play a pivotal role in the development and progression of RA, we have proposed a therapy that would overall suppress inflammation, by expressing anti-inflammatory cytokines. Regarding the vectors of choice, the ideal vector should transfer a precise amount of genetic material into each target cell expressing the gene material, without causing toxicity. As a delivery method for the therapeutic gene, there are several choices available. The most obvious methods are plasmids carrying the therapeutic gene or viral vectors. Because a long-time expression of the transgene is needed for treatment of RA, plasmid vectors are not an option, because they are known for only a short-term expression and often only suboptimal expression of the transgene, although there have been improvements made to overcome these difficulties. Therefore, only viral vectors can be used to transfer the transgene. Viral vectors that will integrate into the genome or stay as an endosomal plasmid present in the cell have a preference. This limits the choice of vectors to viral vectors, such as retro- and lentiviral vectors and AAV. Because the retro- and lentiviral vectors are known for insertional mutagenesis, the preferred vector is AAV.
In the absence of a helper virus or genotoxic factors, AAV DNA can either integrate into the host genome at a predefined spot (chromosome 19) or persist in an episomal form. This makes AAV the vector of choice, because it fulfils all the criteria needed for an effective therapy for RA.
Adeno-associated virus (AAV) is preferred, because it is safe, effective, and less immunogenic than other vectors. Genetic modifications of human cells can be done either by an ex vivo or in vivo approach. Both methods are possible in RA treatment and have been used in different studies. The fact that modified cells were cleared shortly after intra-articular injection was the main disadvantage in several ex vivo studies, thus making in vivo delivery a preferable approach for RA treatment. AAV is commonly used in in vivo studies where the goal is long-term expression, as in RA, because this lowers the frequency of treatment administrations. Specifically, for in vivo gene delivery to the joint by direct intra-articular injection, AAV is safer than other unsuitable-for-clinical-translation vectors that are inflammatory, immunogenic, and can provide more extended periods of transgene expression than non-viral vectors. When it comes to the promoter, a promotor of the pro-inflammatory gene that is active during the onset of an inflammatory response in the joint is preferred, since in this way, expression of the therapeutic gene can be achieved locally and specifically when RA-related inflammation arises. For this purpose, promotors of TNF?, IL-1?, Cyclooxygenase-2 (Cox2), or nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) would all be suitable to regulate expression of the therapeutic gene, as they are upregulated during inflammation. Finally, the therapeutic gene needs to be an anti-inflammatory agent that will alleviate the phenomenon of inflammation in the joints. ?here are numerous choices, but IL-4 and IFN-? are among the best candidates due to their anti-inflammatory functions.
4.3.3 Stem Cell Therapy
Mesenchymal stem cell (MSC) therapy is a cutting-edge approach to treating rheumatoid arthritis (RA), a chronic autoimmune disorder characterized by chronic inflammation, joint pain, stiffness, and progressive joint destruction.
This therapy leverages the body's own repair mechanisms by utilizing MSCs, which are undifferentiated cells capable of transforming into various cell types necessary for repairing damaged tissues. Mechanism of Action
Figure 10. Stem cell therapy in RA
CONCLUSION
Rheumatoid arthritis is a chronic autoimmune disease with the characteristic features of the destruction of synovium, cartilage and joints. Environmental and genetic factors play an important role in the development of rheumatoid arthritis with occurring pathological events. Many developments have been made to treat the disease and also the diagnosis of the disease. Nanotechnology offers promising new avenues in the treatment of rheumatoid arthritis (RA) by enabling more precise drug delivery, enhancing therapeutic effectiveness, and reducing side effects. Through the use of nanoparticles, drugs can be targeted directly to inflamed joints, minimizing systemic exposure and allowing for lower dosages, which reduces toxicity and improves patient safety. Liposomes, dendrimers, and polymeric nanoparticles are some of the innovative nanomaterials being explored to encapsulate and deliver anti-inflammatory and immunosuppressive drugs specifically to affected areas. Nanotechnology represents a transformative approach in RA treatment, combining targeted therapy, reduced side effects, and enhanced monitoring. As research progresses, these technologies hold the potential to significantly improve the quality of life for RA patients and may one day contribute to more definitive, possibly even curative, treatments. Gene therapy represents an exciting frontier in RA treatment, offering the possibility of long-lasting relief and the potential for disease modification. As advancements continue, gene therapy could lead to more effective, personalized, and potentially curative solutions for RA, significantly improving patient outcomes and quality of life. stem cell therapy offers a hopeful avenue for treating rheumatoid arthritis, with the potential to improve patients’ quality of life by addressing the root causes of the disease. However, more research is needed to validate these benefits and ensure safe application, making it a promising but still emerging treatment option. These include optimizing cell types and delivery methods, determining long-term safety and effectiveness, and addressing potential risks like infection or tumor formation
REFERENCES
Shweta Katkade*, Vikas Shinde, New Avenues in Treatment of Rheumatoid Arthritis: A Comprehensive Review, Int. J. of Pharm. Sci., 2024, Vol 2, Issue 11, 633-653. https://doi.org/10.5281/zenodo.14161991
10.5281/zenodo.14161991
