B cells influence sex specificity of arthritis via myeloid suppressors and chemokines in humanized mice

Rituximab exerts its anti-arthritic effects via inhibiting NF-κB/GM-CSF/iNOS signaling in B cells in a mouse model of collagen-induced arthritis

Rheumatoidarthritis (RA) is an autoimmune disease characterized by uncontrolled joint inflammation and damage to bone and cartilage. B cells are known to play a crucial role in the pathogenesis and development of arthritis. Previous studies have found that B cells may be a potential target for treating RA. Rituximab, a monoclonal antibody targeting B cells, has induced long-term clinical responses in RA. Collagen-induced arthritis (CIA) mouse model is a widely studied autoimmune model of RA. CIA mouse model was used to investigate the effect of rituximab on the RA severity in the mice. Following induction of CIA, animals were treated with rituximab (250 mg/kg/week) intraperitoneally on the days 28, 35, 42, 49, 56, and 63 after collagen induction. We investigated the effect of rituximab on NF-κB p65, IκBα, GM-CSF, MCP-1, iNOS, TNF-α, and IL-6 cells in splenic CD19⁺ and CD45R⁺ B cells using flow cytometry. We also assessed the effect of rituximab on NF-κB p65, GM-CSF, IκBα, MCP-1, iNOS, TNF-α, and IL-6 at mRNA levels using RT-PCR analyses of knee tissues. Rituximab treatment significantly decreased CD19⁺NF-κB p65⁺, CD45R⁺NF-κB p65⁺, CD19⁺GM-CSF⁺, CD45R⁺GM-CSF⁺, CD19⁺MCP-1⁺, CD45R⁺MCP-1⁺, CD19⁺TNF-α⁺, CD45R⁺TNF-α⁺, CD19⁺iNOS⁺, CD45R⁺iNOS⁺, CD19⁺IL-6⁺, and CD45R⁺IL-6⁺, and increased CD45R⁺IκBα⁺ in spleen cells of CIA mice. We further observed that rituximab treatment downregulated NF-κB p65, GM-CSF, MCP-1, iNOS, TNF-α, and IL-6, whereas it upregulated IκBα, mRNA level. All these findings suggest that rituximab may be a novel therapeutic target for the treatment of RA.

Treatment with the anti-CD20 monoclonal antibody rituximab mitigates gonadal disruptions in the collagen-induced arthritis in male DBA/1 J mouse model

Rheumatoid arthritis (RA), which is driven by persistent activation of the immune system, primarily affects the joints. Several reports have estimated the risk of gonadal disruptions in arthritic patients, with potential attributable risk factors such as treatments with the disease-modifying antirheumatic drugs and the influence of the disease itself. The FDA approved rituximab, a therapy for non-Hodgkin's lymphoma, for management of RA in February 2006. However, the influence of repeated treatment with rituximab on gonadal function in RA has not been reported yet. Thus, the aim of the presents study is to evaluate whether repeated treatment with the clinically relevant dose of rituximab may change the gonadal disruptions in collagen-induced arthritis in male DBA/1 J mouse, a model of RA. Testicular disruptions, as determined by the sperm DNA strand breaks, spermatocyte chromosomal analysis and spermiogram examination have been conducted by the use of standard techniques. Additionally, we aimed to test whether the anti-rheumatic effect of rituximab also decreases the cellular oxidant-antioxidant imbalance in arthritic male DBA/1 J mice. Repeated treatment of naïve control DBA/1 J mice with rituximab did not exhibit any significant deleterious effects. Moreover, repeated administration of rituximab to the arthritic DBA/1 J mice suppressed disease severity and decreased testicular disruptions. Rituximab treatment also diminished gonadal oxidative stress, through decreasing reactive oxygen species generation and restoring the reduced glutathione level in arthritic DBA/1 J mice. In conclusion, rituximab is a safe therapeutic agent and can mitigate gonadal disruptions induced by arthritis, which insinuates the importance for arthritic patients especially at reproductive age.

Sexual dimorphism in immunometabolism and autoimmunity: Impact on personalized medicine

Immune cells play essential roles in metabolic homeostasis and thus, undergo analogous changes in normal physiology (e.g., puberty and pregnancy) and in various metabolic and immune diseases. An essential component of this close relationship between the two is sex differences. Many autoimmune diseases, such as systemic lupus erythematous and multiple sclerosis, feature strikingly increased prevalence in females, whereas in contrast, infectious diseases, such as Ebola and Middle East Respiratory Syndrome, affect more men than women. Therefore, there are fundamental aspects of metabolic homeostasis and immune functions that are regulated differently in males and females. This can be observed in sex hormone-immune interaction where androgens, such as testosterone, have shown immunosuppressive effects whilst estrogen is on the opposite side of the spectrum with immunoenhancing facilitation of mechanisms. In addition, the two sexes exhibit significant differences in metabolic regulation, with estrous cycles in females known to induce variability in traits and more pronounced metabolic disease phenotype exhibited by males. It is likely that these differences underlie both the development of metabolic and autoimmune diseases and the response to current treatment options. Sexual dimorphism in immunometabolism has emerged to become an area of intense research, aiming to uncover sex-biased effector molecules in the various metabolic tissues and immune cell types, identify sex-biased cell-type-specific functions of common effector molecules, and understand whether the sex differences in metabolic and immune functions influence each other during autoimmune pathogenesis. In this review, we will summarize recent findings that address these critical questions of sexual dimorphism in immunometabolism as well as their translational implications for the clinical management of autoimmune diseases.

Sexual dimorphism, aging and immunity

Health and lifespan disparities between sexes are dependent on the immune responses. Men and women have different life styles which determine the environment, nutritional requirements and their interactions with the sex hormones. Sexual dimorphism in innate and adaptive immunity determines responses to infections and other environmental factors regulating health and diseases. Sex hormones regulate immune responses through the expression of receptors which differ for female and male hormones. Estrogen receptors are expressed in brain, lymphoid tissue cells and many immune cells while androgen receptors are limited in expression. Genetic, epigenetic factors and X chromosome linked immune function genes are important in enhanced adaptive immunity in females, leading to production of higher levels of antibodies compared to males. Different nutritional requirements and hormonal control of the mucosal microbiome and its function regulate mucosal immunity. Hormonal changes during various aspects of life and during aging control immune senescence. Evolutionarily, females have an advantage during young age when they are protected from infections by heightened immune reactivity though during aging that can lead to pathologies. Considering the sexual dimorphism in immunity, guidelines need to be established for sex-based treatments for optimal response.

Intravenous injection of autologous bone marrow-derived mesenchymal stem cells on the gene expression and plasma level of CCL5 in refractory rheumatoid arthritis

Background:

Rheumatoid arthritis (RA) is the most prevalent autoimmune disease, in which CCL2 and CCL5 are critically involved. The objective was to evaluate the therapeutic effects of bone marrow-derived mesenchymal stem cells (MSCs) on the foregoing chemokines in RA patients.

Materials and Methods:

Thirteen RA patients were evaluated in terms of clinical manifestations, paraclinical factors, gene expression, and plasma levels of CCL2 and CCL5 prior to treatment and 1 and 6 months after intervention. Real-time-polymerase chain reaction and enzyme-linked immunosorbent assay were employed to assess the gene expression and plasma levels of CCL2 and CCL5 at different time points after MSC therapy. Statistical analysis was performed by SPSS 16 and Prism 7.

Results:

The CCL2 gene expression had statistically significantly increased (P = 0.034), and its plasma level had insignificantly reduced after 1 month. Furthermore, the gene expression and plasma level of CCL5 had statistically significantly decreased (P = 0.032, P < 0.001). The CCL5 gene expression had statistically significantly increased after 6 months (P = 0.001) and its plasma level had insignificantly reduced.

Conclusion:

The most significant inhibitory effects of MSC therapy on the gene expression and plasma level of CCL5 were observed at the end of 1 month. The differences between the gene expression and protein levels during the treatment might be related to microRNA effects or the insufficient number of MSC injection.

Therapeutic Cytokine Inhibition Modulates Activation and Homing Receptors of Peripheral Memory B Cell Subsets in Rheumatoid Arthritis Patients

Memory B cells have known to play an important role in the pathogenesis of rheumatoid arthritis (RA). With the emergence of B cell-targeted therapies, the modulation of memory B cells appears to be a key therapeutic target. Human peripheral memory B cells can be distinguished based on the phenotypic expression of CD27 and IgD, characterizing the three major B cell subpopulations: CD27+IgD+ pre-switch, CD27+IgD- post-switch, and CD27-IgD- double-negative memory B cells. We evaluated different memory cell populations for activation markers (CD95 and Ki-67) and chemokine receptors (CXCR3 and 4) expressing B cells in active RA, as well as under IL6-R blockade by tocilizumab (TCZ) and TNF-α blockade by adalimumab (ADA). Memory B cells were phenotypically analyzed from RA patients at baseline, week 12, and week 24 under TCZ or ADA treatment, respectively. Using flow cytometry, surface expression of CD95, intracellular Ki-67, and surface expressions of CXCR3 and CXCR4 were determined. Compared with healthy donors (n = 40), the phenotypic analysis of RA patients (n = 80) demonstrated that all three types of memory B cells were activated in RA patients. Surface and intracellular staining of B cells showed a significantly higher percentage of CD95+ (p < 0.0001) and Ki-67+ (p < 0.0001) cells, with numerically altered CXCR3+ and CXCR4+ cells in RA. CD95 and Ki-67 expressions were highest in post-switch memory B cells, whereas CD19+CXCR3+ and CD19+CXCR4+ expressing cells were substantially higher in the pre-switch compartment. In all subsets of the memory B cells, in vivo IL-6R, and TNF-α blockade significantly reduced the enhanced expressions of CD95 and Ki-67. Based on our findings, we conclude that the three major peripheral memory B cell populations, pre-, post-switch, and double-negative B cells, are activated in RA, demonstrating enhanced CD95 and Ki-67 expressions, and varied expression of CXCR3 and CXCR4 chemokine receptors when compared with healthy individuals. This activation can be efficaciously modulated under cytokine inhibition in vivo.

HLA transgenic mice: application in reproducing idiosyncratic drug toxicity

Various types of transgenic mice carrying either class I or II human leukocyte antigen (HLA) molecules are readily available, and reports describing their use in a variety of studies have been published for more than 30 years. Examples of their use include the discovery of HLA-specific antigens against viral infection as well as the reproduction of HLA-mediated autoimmune diseases for the development of therapeutic strategies. Recently, HLA transgenic mice have been used to reproduce HLA-mediated idiosyncratic drug toxicity (IDT), a rare and unpredictable adverse drug reaction that can result in death. For example, abacavir-induced IDT has successfully been reproduced in HLA-B*57:01 transgenic mice. Several reports using HLA transgenic mice for IDT have proven the utility of this concept for the evaluation of IDT using various HLA allele combinations and drugs. It has become apparent that such models may be a valuable tool to investigate the mechanisms underlying HLA-mediated IDT. This review summarizes the latest findings in the area of HLA transgenic mouse models and discusses the current challenges that must be overcome to maximize the potential of this unique animal model.