The central and multiple roles of B cells in lupus pathogenesis

Suppression of skin lesions and SLE nephritis by increasing Treg in MRL/FASlpr mice by administration of bee venom Apitoxin®

BACKGROUND

Apitoxin®, a drug based on bee venom was approved and released in Korea in 2003 as the ethical drug (ETC). It is well-known for its pain-relieving properties due to its potent anti-inflammatory effects. This raises the question of whether bee venom has benefits for other inflammatory disorders. Since its effectiveness in treating inflammation and pain associated with autoimmune diseases has been observed in several clinical cases in Korea, we conducted an efficacy study using an animal model of the systemic lupus erythematosus (SLE), an autoimmune disease with high medical unmet needs. In this research, we aim to confirm the potential therapeutic efficacy for SLE through the immunomodulation induced by bee venom.

METHODS

MRL/FASlpr mice were injected subcutaneously with Apitoxin® and evaluated for clinical parameters including proteinuria, skin lesions, and lymphadenopathy, flow cytometric evaluation of regulatory T cells (Treg), quantitative evaluation of anti-dsDNA antibody in serum by ELISA, and histomorphometric analysis of kidney tissues.

RESULTS

Treatment with Apitoxin® revealed a reduction in proteinuria, skin lesions, and lymphadenopathy in MRL/FASlpr mice. The percentage of CD3+CD4+CD25+FoxP3 (Treg) cells, which are associated with autoimmune diseases, was increased compared to the negative control (vehicle). Quantitative analysis of autoantibodies in the blood of MRL/FASlpr mice showed a decreasing tendency in the treatment groups with Apitoxin®. Moreover, mesangial proliferation and inflammatory cell infiltration in glomeruli were significantly reduced in the treatment group with Apitoxin®, which was associated with a statistically significant decrease in the amount of IgG infiltrated into the glomeruli.

CONCLUSION

Overall, the results confirmed that Apitoxin® induced clinical improvement in SLE by increasing the proportion of Treg cells and decreasing anti-dsDNA antibodies in the blood, which resulted in therapeutic effects on glomerulonephritis associated with decreased renal infiltration of immune complexes.

Dysregulated CXCL12 expression in osteoblasts promotes B-lymphocytes preferentially homing to the bone marrow in MRL/lpr mice

Objective: Todetect the abnormal distribution of B-lymphocytes between peripheral and bone marrow (BM) compartments and explore the mechanism of abnormal chemotaxis of B-lymphocytes in lupus subjects. Methods: The proportions of CXC chemokine receptor (CXCR)4+ B cells and CFDA-labeled MRL/lpr-derived B cells were detected by flow cytometry. The levels of CXC chemokine ligand (CXCL)12in peripheral blood (PB)were measured by ELISA. The migrated B cells to osteoblasts (OBs) was measured by transwell migration assay. The relative spatial position of B cells, OBs and CXCL12 was presented by Immunofluorescence assay. Results: Firstly, we found that the percentage of CXCR4+ B cells was lower in PB and higher in the BM from both MRL/lpr mice and patientswith Systemic lupus erythematosus (SLE). Secondly, OBs from MRL/lpr mice produced more CXCL12 than that from C57BL/6 mice. Besides, MRL/lpr-derived OBs demonstrated more potent chemotactic ability toward B-lymphocytes than control OBs by vitro an vivo. Additionally, more B-lymphocytes were found to co-localize with OBs within the periosteal zone of bone in MRL/lpr mice. Lastly, the percentages of CXCR4+B cells were found to be negatively correlated with serum Immunoglobulin (Ig) G concentration, moreover, BM CXCL12 levels were found to be positively correlated with SLE disease activity index Score and negatively correlated with serum Complement3 (C3) concentration. Conclusions: our results indicated that there is a shifted distribution of B-lymphocytes between BM and peripheral compartments in both SLE patients and MRL/lpr mice. Besides, the up-regulated levels of CXCL12 in OBs was indicated to contribute to the enhanced chemotactic migration and anchorage of B-lymphocytes to OBs.

The role of gut microbiota in different murine models of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by immune system dysfunction that can lead to serious health issues and mortality. Recent investigations highlight the role of gut microbiota alterations in modulating inflammation and disease severity in SLE. This review specifically summaries the variations in gut microbiota composition across various murine models of lupus. By focusing on these differences, we aim to elucidate the intricate relationship between gut microbiota dysbiosis and the development and progression of SLE in preclinical settings.

EAF2 deficiency attenuates autoimmune disease in Fas lpr mice by modulating B cell activation and apoptosis

MRL/lpr mice develop systemic lupus erythematosus-like autoimmunity due to defective FAS-mediated apoptosis. We generated Fas lpr mice deficient in EAF2, a transcription elongation-associated factor known to promote apoptosis in germinal center (GC) B cells and crucial for preventing autoimmunity. Contrary to expectations, EAF2 deficiency significantly reduced lymphadenopathy and splenomegaly, extended lifespan, and alleviated nephritis by decreasing renal immune complex deposition. Additionally, EAF2 deficiency markedly reduced accumulation of activated B cells, GC B cells, plasma cells, and the abnormal B220+CD3+ T cells in Fas lpr mice. Further analysis revealed that Eaf2 -/- Fas lpr B cells showed hyperactivation upon various stimulations, followed by increased death. RNA sequencing of the B220+CD3+ cells revealed a downregulation in survival-promoting genes such as Bcl-2 and Akt and an upregulation of proapoptotic genes. We conclude that the combined deficiency in FAS- and EAF2-mediated apoptotic pathways leads to B cell hyperactivation and subsequent death, thereby ameliorating systemic autoimmunity in this model.

How Do ROS Induce NETosis? Oxidative DNA Damage, DNA Repair, and Chromatin Decondensation

Neutrophil extracellular traps (NETs) are intricate, DNA-based, web-like structures adorned with cytotoxic proteins. They play a crucial role in antimicrobial defense but are also implicated in autoimmune diseases and tissue injury. The process of NET formation, known as NETosis, is a regulated cell death mechanism that involves the release of these structures and is unique to neutrophils. NETosis is heavily dependent on the production of reactive oxygen species (ROS), which can be generated either through NADPH oxidase (NOX) or mitochondrial pathways, leading to NOX-dependent or NOX-independent NETosis, respectively. Recent research has revealed an intricate interplay between ROS production, DNA repair, and NET formation in different contexts. UV radiation can trigger a combined process of NETosis and apoptosis, known as apoNETosis, driven by mitochondrial ROS and DNA repair. Similarly, in calcium ionophore-induced NETosis, both ROS and DNA repair are key components, but only play a partial role. In the case of bacterial infections, the early stages of DNA repair are pivotal. Interestingly, in serum-free conditions, spontaneous NETosis occurs through NOX-derived ROS, with early-stage DNA repair inhibition halting the process, while late-stage inhibition increases it. The intricate balance between DNA repair processes and ROS production appears to be a critical factor in regulating NET formation, with different pathways being activated depending on the nature of the stimulus. These findings not only deepen our understanding of the mechanisms behind NETosis but also suggest potential therapeutic targets for conditions where NETs contribute to disease pathology.

Lymphocytes Change Their Phenotype and Function in Systemic Lupus Erythematosus and Lupus Nephritis

Systemic lupus erythematosus (SLE) is a complex autoimmune disease, characterized by considerable changes in peripheral lymphocyte structure and function, that plays a critical role in commencing and reviving the inflammatory and immune signaling pathways. In healthy individuals, B lymphocytes have a major role in guiding and directing defense mechanisms against pathogens. Certain changes in B lymphocyte phenotype, including alterations in surface and endosomal receptors, occur in the presence of SLE and lead to dysregulation of peripheral B lymphocyte subpopulations. Functional changes are characterized by loss of self-tolerance, intra- and extrafollicular activation, and increased cytokine and autoantibody production. T lymphocytes seem to have a supporting, rather than a leading, role in the disease pathogenesis. Substantial aberrations in peripheral T lymphocyte subsets are evident, and include a reduction of cytotoxic, regulatory, and advanced differentiated subtypes, together with an increase of activated and autoreactive forms and abnormalities in follicular T cells. Up-regulated subpopulations, such as central and effector memory T cells, produce pre-inflammatory cytokines, activate B lymphocytes, and stimulate cell signaling pathways. This review explores the pivotal roles of B and T lymphocytes in the pathogenesis of SLE and Lupus Nephritis, emphasizing the multifaceted mechanisms and interactions and their phenotypic and functional dysregulations.

Frontiers in CAR-T cell therapy for autoimmune diseases

Chimeric antigen receptor (CAR)-engineered T (CAR-T) cell therapy has demonstrated significant success in treating cancers. The potential of CAR-T cells is now being explored in the context of autoimmune diseases. Recent clinical trials have shown sustained and profound elimination of autoreactive B cells by CAR-T cells, leading to promising autoimmune disease control with minimal safety concerns. These encouraging results have inspired further investigation into CAR-T cell applications for a broader range of autoimmune diseases and the development of advanced cell products with improved efficacy and safety. In this review, we discuss the mechanisms by which CAR-T cells target autoimmune conditions, summarize current preclinical models, and highlight ongoing clinical trials, including CAR-T therapy design, clinical outcomes, and challenges. Additionally, we discuss the limitations and future directions of CAR-T therapy in the treatment of autoimmune diseases.

Dysregulated balance in Th17/Treg axis of Pristane-induced lupus mouse model, are mesenchymal stem cells therapeutic?

BACKGROUND

Despite advances in general and targeted immunosuppressive therapies, limiting all mainstay treatment options in refractory systemic lupus erythematosus (SLE) cases has necessitated the development of new therapeutic strategies. Mesenchymal stem cells (MSCs) have recently emerged with unique properties, including a solid propensity to reduce inflammation, exert immunomodulatory effects, and repair injured tissues.

METHODS

An animal model of acquired SLE mice was induced via intraperitoneal immunization with Pristane and affirmed by measuring specific biomarkers. Bone marrow (BM) MSCs were isolated from healthy BALB/c mice and cultured in vitro, then were identified and confirmed by flow cytometry and cytodifferentiation. Systemic MSCs transplantation was performed and then several parameters were analyzed and compared, including specific cytokines (IL-17, IL-4, IFN-ɣ, TGF-β) at the serum level, the percentage of Th cell subsets (Treg/Th17, Th1/Th2) in splenocytes, and also the relief of lupus nephritis, respectively by enzyme-linked immunosorbent assay (ELISA), flow cytometry analysis and by hematoxylin & eosin staining and also immunofluorescence assessment. Experiments were carried out with different initiation treatment time points (early and late stages of disease). Analysis of variance (ANOVA) followed by post hoc Tukey's test was used for multiple comparisons.

RESULTS

The rate of proteinuria, anti-double-stranded deoxyribonucleic acid (anti-dsDNA) antibodies, and serum creatinine levels decreased with BM-MSCs transplantation. These results were associated with attenuated lupus renal pathology in terms of reducing IgG and C3 deposition and lymphocyte infiltration. Our findings suggested that TGF-β (associated with lupus microenvironment) can contribute to MSC-based immunotherapy by modulating the population of TCD4⁺ cell subsets. Obtained results indicated that MSCs-based cytotherapy could negatively affect the progression of induced SLE by recovering the function of Treg cells, suppressing Th1, Th2, and Th17 lymphocyte function, and downregulating their pro-inflammatory cytokines.

CONCLUSION

MSC-based immunotherapy showed a delayed effect on the progression of acquired SLE in a lupus microenvironment-dependent manner. Allogenic MSCs transplantation revealed the ability to re-establish the balance of Th17/Treg, Th1/Th2 and restore the plasma cytokines network in a pattern dependent on disease conditions. The conflicting results of early versus advanced therapy suggest that MSCs may produce different effects depending on when they are administered and their activation status.

Small molecule inhibitors of nuclear export ameliorate lupus by modulating plasma cell generation and survival

OBJECTIVE

To investigate the hypothesis that selective inhibitors of nuclear export (SINE), recently approved for the treatment of refractory plasma cell (PC) malignancy, may have potential in the treatment of lupus.

METHODS

NZB/NZW female mice were treated with SINE or vehicle control. Tissue was harvested and analyzed by flow cytometry using standard markers. Nephritis was monitored by evaluation for proteinuria and by histologic analysis of kidneys. Serum anti- double-stranded DNA (anti-dsDNA) levels were measured by enzyme-linked immunosorbent assay (ELISA) and total IgG and dsDNA antibody-secreting cells (ASC) by enzyme-linked immunospot assay.

RESULTS

SINE abrogated murine lupus nephritis at both early and late stages of the disease and rapidly impaired generation of autoreactive PC in germinal centers (GC). SINE inhibited the production of the NF-κB-driven homeostatic chemokines by stromal cells, altering splenic B and T cell strategic positioning and significantly reducing T follicular helper cells (TFH), GC B cells, and autoreactive PC. SINE also decreased cytokines/chemokines involved in PC survival and recruitment in the kidney of lupus-prone mice. Exportin 1, the SINE target, was detected in GC of human tonsils, splenic B cells of lupus patients, and multiple B cell subsets in the kidney of patients with lupus nephritis.

CONCLUSION

Our collective results support the therapeutic potential of SINE via targeting several molecular and cellular pathways critical in lupus pathogenesis, including autoantibody production by plasma cells.

Involvement of IL-33 in the Pathophysiology of Systemic Lupus Erythematosus: Review

IL-33 is a newly discovered cytokine displaying pleiotropic localizations and functions. More specifically, it also functions as an alarmin, following its release from cells undergoing cell death or necrosis, to alert the innate immune system. The role of IL-33 has been underlined in several inflammatory and autoimmune diseases including systemic lupus erythematosus (SLE). The expressions of IL-33 as well as its receptor, ST2, are significantly upregulated in SLE patients and in patients with lupus nephritis. This review discusses the involvement of IL-33 in the pathology of SLE.

CoRE-ATAC: A deep learning model for the functional classification of regulatory elements from single cell and bulk ATAC-seq data

Cis-Regulatory elements (cis-REs) include promoters, enhancers, and insulators that regulate gene expression programs via binding of transcription factors. ATAC-seq technology effectively identifies active cis-REs in a given cell type (including from single cells) by mapping accessible chromatin at base-pair resolution. However, these maps are not immediately useful for inferring specific functions of cis-REs. For this purpose, we developed a deep learning framework (CoRE-ATAC) with novel data encoders that integrate DNA sequence (reference or personal genotypes) with ATAC-seq cut sites and read pileups. CoRE-ATAC was trained on 4 cell types (n = 6 samples/replicates) and accurately predicted known cis-RE functions from 7 cell types (n = 40 samples) that were not used in model training (mean average precision = 0.80, mean F1 score = 0.70). CoRE-ATAC enhancer predictions from 19 human islet samples coincided with genetically modulated gain/loss of enhancer activity, which was confirmed by massively parallel reporter assays (MPRAs). Finally, CoRE-ATAC effectively inferred cis-RE function from aggregate single nucleus ATAC-seq (snATAC) data from human blood-derived immune cells that overlapped with known functional annotations in sorted immune cells, which established the efficacy of these models to study cis-RE functions of rare cells without the need for cell sorting. ATAC-seq maps from primary human cells reveal individual- and cell-specific variation in cis-RE activity. CoRE-ATAC increases the functional resolution of these maps, a critical step for studying regulatory disruptions behind diseases.

Dependence on Autophagy for Autoreactive Memory B Cells in the Development of Pristane-Induced Lupus

The production of autoantibodies by autoreactive B cells plays a major role in the pathogenesis of lupus. Increases in memory B cells have been observed in human lupus patients and autoimmune lpr mice. Autophagy is required for the maintenance of memory B cells against viral infections; however, whether autophagy regulates the persistence of autoantigen-specific memory B cells and the development of lupus remains to be determined. Here we show that memory B cells specific for autoantigens can be detected in autoimmune lpr mice and a pristane-induced lupus mouse model. Interestingly, B cell-specific deletion of Atg7 led to significant loss of autoreactive memory B cells and reduced autoantibody production in pristane-treated mice. Autophagy deficiency also attenuated the development of autoimmune glomerulonephritis and pulmonary inflammation after pristane treatment. Adoptive transfer of wild type autoreactive memory B cells restored autoantibody production in Atg7-deficient recipients. These data suggest that autophagy is important for the persistence of autoreactive memory B cells in mediating autoantibody responses. Our results suggest that autophagy could be targeted to suppress autoreactive memory B cells and ameliorate humoral autoimmunity.

Harnessing Tolerogenic Histone Peptide Epitopes From Nucleosomes for Selective Down-Regulation of Pathogenic Autoimmune Response in Lupus (Past, Present, and Future)

Autoantigen-directed tolerance can be induced by certain nucleosomal histone peptide epitope/s in nanomolar dosage leading to sustained remission of disease in mice with spontaneous SLE. By contrast, lupus is accelerated by administration of intact (whole) histones, or whole nucleosomes in microparticles from apoptotic cells, or by post-translationally acetylated histone-peptides. Low-dose therapy with the histone-peptide epitopes simultaneously induces TGFβ and inhibits IL-6 production by DC in vivo, especially pDC, which then induce CD4+CD25+ Treg and CD8+ Treg cells that suppress pathogenic autoimmune response. Both types of induced Treg cells are FoxP3+ and act by producing TGFβ at close cell-to-cell range. No anaphylactic adverse reactions, or generalized immunosuppression have been detected in mice injected with the peptides, because the epitopes are derived from evolutionarily conserved histones in the chromatin; and the peptides are expressed in the thymus during ontogeny, and their native sequences have not been altered. The peptide-induced Treg cells can block severe lupus on adoptive transfer reducing inflammatory cell reaction and infiltration in the kidney. In Humans, similar potent Treg cells are generated by the histone peptide epitopes in vitro in lupus patients’ PBMC, inhibiting anti-dsDNA autoantibody and interferon production. Furthermore, the same types of Treg cells are generated in lupus patients who are in very long-term remission (2-8 years) after undergoing autologous hematopoietic stem cell transplantation. These Treg cells are not found in lupus patients treated conventionally into clinical remission (SLEDAI of 0); and consequently they still harbor pathogenic autoimmune cells, causing subclinical damage. Although antigen-specific therapy with pinpoint accuracy is suitable for straight-forward organ-specific autoimmune diseases, Systemic Lupus is much more complex. The histone peptide epitopes have unique tolerogenic properties for inhibiting Innate immune cells (DC), T cells and B cell populations that are both antigen-specifically and cross-reactively involved in the pathogenic autoimmune response in lupus. The histone peptide tolerance is a natural and non-toxic therapy suitable for treating early lupus, and also maintaining lupus patients after toxic drug therapy. The experimental steps, challenges and possible solutions for successful therapy with these peptide epitopes are discussed in this highly focused review on Systemic Lupus.

The Type II Anti-CD20 Antibody Obinutuzumab (GA101) Is More Effective Than Rituximab at Depleting B Cells and Treating Disease in a Murine Lupus Model

OBJECTIVE

Depleting pathogenic B cells could treat systemic lupus erythematosus (SLE). However, depleting B cells in an inflammatory setting such as lupus is difficult. This study was undertaken to investigate whether a type II anti-CD20 monoclonal antibody (mAb) with a different mechanism of action, obinutuzumab (GA101), is more effective than a type I anti-CD20 mAb, rituximab (RTX), in B cell depletion in lupus, and whether efficient B cell depletion results in amelioration of disease.

METHODS

We treated lupus-prone MRL/lpr mice expressing human CD20 on B cells (hCD20 MRL/lpr mice) with either RTX or GA101 and measured B cell depletion under various conditions, as well as multiple clinical end points.

RESULTS

A single dose of GA101 was markedly more effective than RTX in depleting B cells in diseased MRL/lpr mice (P < 0.05). RTX overcame resistance to B cell depletion in diseased MRL/lpr mice with continuous treatments. GA101 was more effective in treating hCD20 MRL/lpr mice with early disease, as GA101-treated mice had reduced glomerulonephritis (P < 0.05), lower anti-RNA autoantibody titers (P < 0.05), and fewer activated CD4+ T cells (P < 0.0001) compared to RTX-treated mice. GA101 also treated advanced disease, and continual treatment prolonged survival. Using variants of GA101, we also elucidated B cell depletion mechanisms in vivo in mice with lupus.

CONCLUSION

Albeit both anti-CD20 antibodies ameliorated early disease, GA101 was more effective than RTX in important parameters, such as glomerulonephritis score. GA101 proved beneficial in an advanced disease model, where it prolonged survival. These data support clinical testing of GA101 in SLE and lupus nephritis.

An updated advance of autoantibodies in autoimmune diseases

Autoantibodies are abnormal antibodies which are generated by pathogenic B cells when targeting an individual's own tissue. Autoantibodies have been identified as a symbol of autoimmune disorders and are frequently considered a clinical marker of these disorders. Autoimmune diseases, including system lupus erythematosus and rheumatoid arthritis, consist of a series of disorders that share some similarities and differences. They are characterized by chronic, systemic, excessive immune activation and inflammation and involve in almost all body tissues. Autoimmune diseases occur more frequently in women than men due to hormonal impacts. In this review we systemically introduce and summarize the latest advances of various autoantibodies in multiple autoimmune diseases.

The Antigen Presenting Potential of CD21low B Cells

Human CD21^low B cells are expanded in autoimmune (AI) diseases and display a unique phenotype with high expression of co-stimulatory molecules, compatible with a potential role as antigen-presenting cells (APCs). Thus, we addressed the co-stimulatory capacity of naïve-like, IgM-memory, switched memory and CD27^negIgD^neg memory CD21^low B cells in allogenic co-cultures with CD4 T cells. CD21^low B cells of patients with AI disorders expressed high levels of not only CD86, CD80, and HLA-DR (memory B cells) but also PD-L1 ex vivo and efficiently co-stimulated CD4 T cells of healthy donors (HD), as measured by upregulation of CD25, CD69, inducible co-stimulator (ICOS), and programmed cell death protein 1 (PD-1) and induction of cytokines. While the co-stimulatory capacity of the different CD21^low B-cell populations was over all comparable to CD21^pos counterparts of patients and HD, especially switched memory CD21^low B cells lacked the increased capacity of CD21^pos switched memory B-cells to induce high expression of ICOS, IL-2, IL-10, and IFN-γ. Acknowledging the limitation of the in vitro setting, CD21^low B cells do not seem to preferentially support a specific T_h effector response. In summary, our data implies that CD21^low B cells of patients with AI diseases can become competent APCs and may, when enriched for autoreactive B-cell receptors (BCR), potentially contribute to AI reactions as cognate interaction partners of autoreactive T cells at sites of inflammation.

The role of B cell antigen presentation in the initiation of CD4+ T cell response

B cells have been known for their ability to present antigens to T cells for almost 40 years. However, the precise roles of B cell antigen presentation in various immune responses are not completely understood. The term "professional" antigen-presenting cells (APCs) was proposed to distinguish APCs that are required for initiating the immune responses from those use antigen presentation to enhance their own effector functions. Unlike dendritic cells, which are defined as professional APCs for their well-established functions in activating naive T cells, B cells have been shown in the past to mostly present antigens to activated CD4+ T cells mainly to seek help from T helper cells. However, recent evidence suggested that B cells can act as professional APCs under infectious conditions or conditions mimicking viral infections. B cell antigen receptors (BCRs) and the innate receptor Toll-like receptors are activated synergistically in response to pathogens or virus-like particles, under which conditions B cells are not only potent but also the predominant APCs to turn naive CD4+ T cells into T follicular helper cells. The discovery of B cells as professional APCs to initiate CD4+ T cell response provides a new insight for both autoimmune diseases and vaccine development.

B cell checkpoints in autoimmune rheumatic diseases

B cells have important functions in the pathogenesis of autoimmune diseases, including autoimmune rheumatic diseases. In addition to producing autoantibodies, B cells contribute to autoimmunity by serving as professional antigen-presenting cells (APCs), producing cytokines, and through additional mechanisms. B cell activation and effector functions are regulated by immune checkpoints, including both activating and inhibitory checkpoint receptors that contribute to the regulation of B cell tolerance, activation, antigen presentation, T cell help, class switching, antibody production and cytokine production. The various activating checkpoint receptors include B cell activating receptors that engage with cognate receptors on T cells or other cells, as well as Toll-like receptors that can provide dual stimulation to B cells via co-engagement with the B cell receptor. Furthermore, various inhibitory checkpoint receptors, including B cell inhibitory receptors, have important functions in regulating B cell development, activation and effector functions. Therapeutically targeting B cell checkpoints represents a promising strategy for the treatment of a variety of autoimmune rheumatic diseases.

Leptin: an unappreciated key player in SLE

Leptin is the forerunner of the adipokine superfamily and plays a key role in regulating energy expenditure and neuroendocrine function. Researches into leptin put emphasize not only on the metabolic role but also its immunoregulatory effect on immune response through immunocyte activation and cytokine secretion. Leptin acts on receptors that are widespread throughout the body and that are expressed across many tissue types. As a consequence, the abnormal expression of leptin has been found to correlate with a number of diseases, including cancers, autoimmune diseases, and cardiovascular diseases. The significance of leptin in the development of autoimmune diseases is becoming increasingly prominent. Systemic lupus erythematosus (SLE) is a severe atypical autoimmune disease that causes damage to multiple organ systems. It is characterised by the following: impaired clearance of apoptotic cells, loss of tolerance to self-antigens, aberrant activation of T cells and B cells, and chronic inflammation. The heightened immunocyte response in SLE means that these physiological systems are particularly vulnerable to regulation by leptin in addition to being of great significance to the research field. Our current review provides insight into the regulatory roles that leptin plays on immune effector cells in SLE.

Emerging immunotherapies for autoimmune kidney disease

Autoimmunity is a leading cause of chronic kidney disease and loss of native and transplanted kidneys. Conventional immunosuppressive therapies can be effective but are non-specific, noncurative, and risk serious side effects such as life-threatening infection and cancer. Novel therapies and targeted interventions are urgently needed. In this brief review we explore diverse strategies currently in development and under consideration to interrupt underlying disease mechanisms in immune-mediated renal injury. Because autoantibodies are prominent in diagnosis and pathogenesis in multiple human glomerulopathies, we highlight several promising therapies that interfere with functions of early mediators (IgG and complement) of the effector arm and with an epicenter (the germinal center) for induction of humoral immunity.

Mouse models of lupus: what they tell us and what they don't

Lupus is a complex heterogeneous disease characterised by autoantibody production and immune complex deposition followed by damage to target tissues. Animal models of human diseases are an invaluable tool for defining pathogenic mechanisms and testing of novel therapeutic agents. There are perhaps more applicable murine models of lupus than any other human disease. There are spontaneous models of lupus, inducible models of lupus, transgenic-induced lupus, gene knockout induced lupus and humanised mouse models of lupus. These mouse models of lupus have contributed significantly to our knowledge of the pathogenesis of lupus and served as valuable preclinical models for proof of concept for new therapies. Despite their utility, mouse models of lupus have their distinct limitations. Although similar, mouse and human immune systems are different and thus one cannot assume a mechanism for disease in one is translatable to the other. Efficacy and toxicity of compounds can vary significantly between humans and mice, also limiting direct translation. Finally, the heterogeneous aspects of human lupus, both in clinical presentation, underlying pathogenesis and genetics, are not completely represented in current mouse models. Thus, proving a therapy or mechanism of disease in one mouse model is similar to proving a mechanism/therapy in a limited subset of human lupus. These limitations, however, do not marginalise the importance of animal models nor the significant contributions they have made to our understanding of lupus.

CD5+ B lymphocytes in systemic lupus erythematosus patients: relation to disease activity

B cells are essential players in the pathogenic mechanisms of systemic lupus erythematosus (SLE). Although CD5+ B cells have been considered to play a paradoxical role in preventing, rather than inducing autoimmunity, there is no consensus agreement about the proportions of CD5+ B cells population in SLE patients. So, the aim of the present study was to assess blood concentration of CD5+ B cells in patients with SLE and to evaluate their relationship with disease activity and organ damage. We recruited 100 SLE patients and 100 healthy control subjects. Based on SLE disease activity index (SLEDAI), patients were divided into two groups: active SLE (n = 50) and inactive SLE (n = 50). SLE was active when SLEDAI was ≥ 4. The expression of CD5+ B cells was evaluated using flow cytometry to measure the proportions and absolute numbers of the cells. The proportions of CD5+ B cells of total lymphocytes were significantly lower in SLE patients versus controls (4.1 ± 3.9 vs 10.8 ± 5.2%, P = <0.001). CD5+ B cells were significantly decreased in active SLE patients (3.1 ± 2.7%) in comparison to inactive patients (5.2 ± 3.7%) (P = 0.013). CD5+ B cells correlated positively with C3 (r = 0.328, P = 0.020) and C4 (r = 0.355, P = 0.011). CD5+ B cells were significantly decreased in SLE patients compared to healthy controls and they were significantly decreased in active SLE patients in comparison to inactive ones.

Hello from the Other Side: How Autoantibodies Circumvent the Blood-Brain Barrier in Autoimmune Encephalitis

Antibodies against neuronal receptors and synaptic proteins are associated with autoimmune encephalitides (AE) that produce movement and psychiatric disorders. In order to exert their pathological effects on neural circuits, autoantibodies against central nervous system (CNS) targets must gain access to the brain and spinal cord by crossing the blood–brain barrier (BBB), a tightly regulated gateway formed by endothelial cells lining CNS blood vessels. To date, the pathogenic mechanisms that underlie autoantibody-triggered encephalitic syndromes are poorly understood, and how autoantibodies breach the barrier remains obscure for almost all AE syndromes. The relative importance of cellular versus humoral immune mechanisms for disease pathogenesis also remains largely unexplored. Here, we review the proposed triggers for various autoimmune encephalopathies and their animal models, as well as basic structural features of the BBB and how they differ among various CNS regions, a feature that likely underlies some regional aspects of autoimmune encephalitis pathogenesis. We then discuss the routes that antibodies and immune cells employ to enter the CNS and their implications for AE. Finally, we explore future therapeutic strategies that may either preserve or restore barrier function and thereby limit immune cell and autoantibody infiltration into the CNS. Recent mechanistic insights into CNS autoantibody entry indicate promising future directions for therapeutic intervention beyond current, short-lived therapies that eliminate circulating autoantibodies.

Mechanisms by Which B Cells and Regulatory T Cells Influence Development of Murine Organ-Specific Autoimmune Diseases

Experiments with B cell-deficient (B−/−) mice indicate that a number of autoimmune diseases require B cells in addition to T cells for their development. Using B−/− Non-obese diabetic (NOD) and NOD.H-2h4 mice, we demonstrated that development of spontaneous autoimmune thyroiditis (SAT), Sjogren’s syndrome and diabetes do not develop in B−/− mice, whereas all three diseases develop in B cell-positive wild-type (WT) mice. B cells are required early in life, since reconstitution of adult mice with B cells or autoantibodies did not restore their ability to develop disease. B cells function as important antigen presenting cells (APC) to initiate activation of autoreactive CD4+ effector T cells. If B cells are absent or greatly reduced in number, other APC will present the antigen, such that Treg are preferentially activated and effector T cells are not activated. In these situations, B−/− or B cell-depleted mice develop the autoimmune disease when T regulatory cells (Treg) are transiently depleted. This review focuses on how B cells influence Treg activation and function, and briefly considers factors that influence the effectiveness of B cell depletion for treatment of autoimmune diseases.

Blisibimod for treatment of systemic lupus erythematosus: with trials you become wiser

INTRODUCTION

Blisibimod is a potent and selective inhibitor of B cell activating factor (BAFF), a mediator of differentiation, maturation and survival of B cells. It has a unique tetravalent, 'peptibody' structure and resulting high potency, and is currently in clinical evaluation for the treatment of SLE. The importance of BAFF in the pathogenesis of systemic lupus erythematosus (SLE) is under intense investigation. The anti BAFF monoclonal antibody belimumab was approved by the FDA for the treatment of SLE.

AREAS COVERED

The general properties of blisibimod are reviewed including pharmacokinetic and pharmacodynamic properties in patients with SLE, efficacy and safety in the phase 2 PEARL-SC and open-label extension trials, and the focus in the ongoing phase 3 trial (CHABLIS-SC1) on the hypothesized 'responder' population. In addition, the rationale for evaluating blisibimod in patients with IgA nephropathy, a common nephritic disease for which there is no approved therapy, is presented.

EXPERT OPINION

Blisibimod's unique tetravalent, peptibody structure and resulting high potency, and the deliberate focus of the Phase 3 clinical development program on the 'responder populations' identified in completed trials in SLE raise the possibility that blisibimod will become an important medication for treatment of SLE and IgA nephropathy.

Beyond pan-B-cell-directed therapy - new avenues and insights into the pathogenesis of SLE

New insights into the mechanisms of autoimmune diseases have been obtained not only from preclinical studies, but also from clinical trials of pan-B-cell-directed therapy. Overall, the results of these clinical trials suggest that more-specific approaches focusing on pathogenic B-cell functions, and perhaps sparing or even enhancing regulatory B-cell activity, might be attractive alternatives. Importantly, pathogenic B-cell subpopulations function within a network of cellular interactions, many of which might require additional interventions to restore immunologic balance and suppress autoimmune disease. Thus, approaches that simultaneously target innate immune cells as well as multiple nodes of T-cell and B-cell interactions might hold the promise of improved therapeutic efficacy. Interfering with B-cell intracellular signalling pathways, altering their intracellular metabolic pathways and perturbing transcription factors are additional options. This Review critically analyses these approaches, examines the role of cytokines and other functions of B-lineage cells separate from antibody secretion, and provides insights into the potential next generation of therapies targeting B-lineage cells.

The role of B cells and autoantibodies in neuropsychiatric lupus

The central nervous system manifestations of SLE (neuropsychiatric lupus, NPSLE) occur frequently, though are often difficult to diagnose and treat. Symptoms of NPSLE can be quite diverse, including chronic cognitive and emotional manifestations, as well as acute presentations, such as stroke and seizures. Although the pathogenesis of NPSLE has yet to be well characterized, B-cell mediated damage is believed to be an important contributor. B-cells and autoantibodies may traverse the blood brain barrier promoting an inflammatory environment consisting of glia activation, neurodegeneration, and consequent averse behavioral outcomes. This review will evaluate the various suggested roles of B-cells and autoantibodies in NPSLE, as well as therapeutic modalities targeting these pathogenic mediators.

Correlation of circulating CD27high plasma cells and disease activity in systemic lupus erythematosus

CD27 is a useful marker in assessing the number of circulating B cells and B cell subsets because it permits one step identification of the major B cell compartments, CD27- naïve and CD27+ memory B cells as well as CD27high plasma cells. Abnormalities in the distributionof CD27+ B cell subsets are useful in assessing disease activity in patients with systemic lupus erythematosus(SLE). In particular, the frequencyof CD27high plasma cells significantly correlates with lupus activity in both children and adults with SLE. Conventional immunosuppressive therapies affect the number of CD27- naive B cells and CD27high plasma cells, but do not target CD27+ memory B cells. These results suggest that disease flares may relate to the retention of CD27+ memory B cells after conventional immunosuppressive therapy and that new therapies that target these cells specifically may offer new opportunities to induce remission in SLE.

B-cell subsets, signaling and their roles in secretion of autoantibodies

B cells play a pivotal role in the pathogenesis of autoimmune diseases. In patients with systemic lupus erythematosus (SLE), the percentages of plasmablasts and IgD−CD27− double-negative memory B cells in peripheral blood are significantly increased, while IgD+CD27+ IgM memory B cells are significantly decreased compared to healthy donors. The phenotypic change is significantly associated with disease activity and concentration of autoantibodies. Treatment of B-cell depletion using rituximab results in the reconstitution of peripheral B cells in SLE patients with subsequent improvement in disease activity. Numerous studies have described abnormalities in B-cell receptor (BCR)-mediated signaling in B cells of SLE patients. Since differences in BCR signaling are considered to dictate the survival or death of naïve and memory B cells, aberrant BCR signal can lead to abnormality of B-cell subsets in SLE patients. Although Syk and Btk function as key molecules in BCR signaling, their pathological role in SLE remains unclear. We found that Syk and Btk do not only transduce activation signal through BCR, but also mediate crosstalk between BCR and Toll-like receptor (TLR) as well as BCR and JAK-STAT pathways in human B cells in vitro. In addition, pronounced Syk and Btk phosphorylation was observed in B cells of patients with active SLE compared to those of healthy individuals. The results suggest the involvement of Syk and Btk activation in abnormalities of BCR-mediated signaling and B-cell phenotypes during the pathological process of SLE and that Syk, Btk and JAK are potential therapeutic targets in SLE.

Several Critical Cell Types, Tissues, and Pathways Are Implicated in Genome-Wide Association Studies for Systemic Lupus Erythematosus

We aimed to elucidate the cell types, tissues, and pathways influenced by common variants in systemic lupus erythematosus (SLE). We applied a nonparameter enrichment statistical approach, termed SNPsea, in 181 single nucleotide polymorphisms (SNPs) that have been identified to be associated with the risk of SLE through genome-wide association studies (GWAS) in Eastern Asian and Caucasian populations, to manipulate the critical cell types, tissues, and pathways. In the two most significant cells’ findings (B lymphocytes and CD14+ monocytes), we subjected the GWAS association evidence in the Han Chinese population to an enrichment test of expression quantitative trait locus (QTL) sites and DNase I hypersensitivity, respectively. In both Eastern Asian and Caucasian populations, we observed that the expression level of SLE GWAS implicated genes was significantly elevated in xeroderma pigentosum B cells (P ≤ 1.00 × 10⁻⁶), CD14+ monocytes (P ≤ 2.74 × 10⁻⁴) and CD19+ B cells (P ≤ 2.00 × 10⁻⁶), and plasmacytoid dendritic cells (pDCs) (P ≤ 9.00 × 10⁻⁶). We revealed that the SLE GWAS-associated variants were more likely to reside in expression QTL in B lymphocytes (q₁/q₀ = 2.15, P = 1.23 × 10⁻⁴⁴) and DNase I hypersensitivity sites (DHSs) in CD14+ monocytes (q₁/q₀ = 1.41, P = 0.08). We observed the common variants affected the risk of SLE mostly through by regulating multiple immune system processes and immune response signaling. This study sheds light on several immune cells and responses, as well as the regulatory effect of common variants in the pathogenesis of SLE.

Immune cells and type 1 IFN in urine of SLE patients correlate with immunopathology in the kidney

The immunopathological events in the kidneys of lupus nephritis (LN) patients are poorly understood due in part to the difficulty in acquiring serial biopsies and the inherent limitations in their analysis. To identify a means to circumvent these limitations, we investigated whether immune cells of kidney origin are present in patient urine and whether they correlate with kidney pathology. Flow cytometry analysis was performed on peripheral blood and urine cells of 69 SLE patients, of whom 41 were LN patients. In addition, type I IFN (IFNα/β) levels were determined in plasma and urine by bioassay. Approximately 60% of non-LN patients had urine lymphocytes. In these patients, T cells were always present and predominantly CD8(+), while B cells were either absent or a mixture of naïve and memory B cells. In contrast, >90% of LN patients had urine lymphocytes. In half, the B and T cells resembled those in non-LN patient urine; however, in the remaining patients, the B cells were exclusively Ig-secreting plasmablasts or plasma cells (PB/PCs) and the T cells were predominantly CD4(+). In addition, pDCs and IFNα/β frequently accompanied PB/PCs. The majority of patients with urine PB/PCs presented with proliferative nephritis and a significant loss of kidney function, which in some cases had progressed to end stage renal disease (ESRD). In conclusion, urine can provide access to cells of kidney resident populations for phenotypic and functional characterization. Analysis of these cells provides insight into the kidney immunopathology and may serve as biomarkers to identify patients at risk for developing LN and progressing to ESRD.

Pharmacokinetics and safety of single doses of tabalumab in subjects with rheumatoid arthritis or systemic lupus erythematosus

AIMS

Two phase 1 studies evaluated the pharmacokinetics (PK), safety and biological activity of tabalumab, a human monoclonal antibody against B-cell activating factor (BAFF), administered intravenously (i.v.) or subcutaneously (s.c.) in subjects with rheumatoid arthritis (RA) or systemic lupus erythematosus (SLE).

METHODS

In study A, subjects with RA (n = 23) or SLE (n = 6) received a single i.v. dose of tabalumab (RA 0.01, 0.04, 0.125, 0.5, 2.0, and 8.0 mg kg(-1) and SLE 0.125 or 2.0 mg kg(-1) ) or placebo. In study B, subjects with RA received a single tabalumab dose i.v. (10 mg) (n = 12) or s.c. (20 mg) (n = 12). Serum tabalumab and CD20+ B cells were evaluated and safety was assessed throughout both studies.

RESULTS

Tabalumab PK were non-linear across the 0.01 to 8.0 mg kg(-1) dose range. Clearance (CL) decreased from 2.9 to 0.1 l day(-1) and terminal half-life (t1/2 ) increased from about 1.6 to 25 days. Subjects with RA or SLE had similar PK. After s.c. dosing, tabalumab time to maximal concentration (tmax ) was 5.5 days. Absolute bioavailability (F) was approximately 62%. Following tabalumab dosing, CD20+ B cells transiently increased from baseline followed by a progressive decrease below baseline.

CONCLUSION

A single tabalumab dose administered i.v. or s.c. was well tolerated and had non-linear CL over the dose range investigated in subjects with RA and SLE. The non-linearity likely reflects target-mediated CL due to binding to BAFF. Tabalumab showed biological activity based on changes in peripheral CD20+ lymphocyte numbers in both subjects with RA and SLE.

Progress with the use of monoclonal antibodies for the treatment of systemic lupus erythematosus

In recent years, significant progress has been made in the use of monoclonal antibodies in the treatment of systemic lupus erythematosus (SLE). Advances in our understanding of the complexity of SLE immunopathogenesis have led to the testing of several biologic agents in clinical trials. Monoclonal therapies currently emerging or under development include B-cell depletion therapies, agents targeting B-cell survival factors, blockade of T-cell co-stimulation and anticytokine therapies. Issues remain, however, regarding clinical trial design and outcome measures in SLE which need to be addressed to optimize translation of these promising therapies into clinical practice.

Toll-Like Receptor-Dependent Immune Complex Activation of B Cells and Dendritic Cells

High titers of autoantibodies reactive with DNA/RNA molecular complexes are characteristic of autoimmune disorders such as systemic lupus erythematosus (SLE). In vitro and in vivo studies have implicated the endosomal Toll-like receptor 9 (TLR9) and Toll-like receptor 7 (TLR7) in the activation of the corresponding autoantibody producing B cells. Importantly, TLR9/TLR7-deficiency results in the inability of autoreactive B cells to proliferate in response to DNA/RNA-associated autoantigens in vitro, and in marked changes in the autoantibody repertoire of autoimmune-prone mice. Uptake of DNA/RNA-associated autoantigen immune complexes (ICs) also leads to activation of dendritic cells (DCs) through TLR9 and TLR7. The initial studies from our lab involved ICs formed by a mixture of autoantibodies and cell debris released from dying cells in culture. To better understand the nature of the mammalian ligands that can effectively activate TLR7 and TLR9, we have developed a methodology for preparing ICs containing defined DNA fragments that recapitulate the immunostimulatory activity of the previous "black box" ICs. As the endosomal TLR7 and TLR9 function optimally from intracellular acidic compartments, we developed a facile methodology to monitor the trafficking of defined DNA ICs by flow cytometry and confocal microscopy. These reagents reveal an important role for nucleic acid sequence, even when the ligand is mammalian DNA and will help illuminate the role of IC trafficking in the response.

NF-κB in inflammation and renal diseases

Nuclear factor κB (NF-κB) is a family of inducible transcription factors that plays a vital role in different aspects of immune responses. NF-κB is normally sequestered in the cytoplasm as inactive complexes via physical association with inhibitory proteins termed IκBs. In response to immune and stress stimuli, NF-κB members become activated via two major signaling pathways, the canonical and noncanonical pathways, and move to the nucleus to exert transcriptional functions. NF-κB is vital for normal immune responses against infections, but deregulated NF-κB activation is a major cause of inflammatory diseases. Accumulated studies suggest the involvement of NF-κB in the pathogenesis of renal inflammation caused by infection, injury, or autoimmune factors. In this review, we discuss the current understanding regarding the activation and function of NF-κB in different types of kidney diseases.

B Cell-Specific MHC Class II Deletion Reveals Multiple Nonredundant Roles for B Cell Antigen Presentation in Murine Lupus

B cells have both Ab-dependent and Ab-independent functions in systemic autoimmune diseases, including systemic lupus erythematosus (SLE). Ab-independent functions are known to be important, because mice with B cells but no secreted Ig have severe disease. These functions could include roles in lymphoid development, cytokine secretion, and Ag presentation; however, these possibilities have not been directly tested in SLE models. In this study, we show by lineage-specific ablation of MHC class II (MHCII) that B cell Ag presentation plays a nonredundant role in CD4(+) T cell activation and effector differentiation in the MRL.Fas(lpr) mouse model of SLE. MHCII-mediated interactions between B and T cells further promote B cell proliferation and differentiation, and, in fact, inefficient MHCII deletion on B cells led to strong selection of escaped cells in activated and plasmablast compartments, further underscoring the central role of B cell Ag presentation. Despite the leakiness in the system, B cell-specific MHCII deletion resulted in substantially ameliorated clinical disease. Hence, B cell Ag presentation is critical for T and B cell activation and differentiation, as well as target organ damage.

Regulatory T cells in B-cell-deficient and wild-type mice differ functionally and in expression of cell surface markers

NOD.H-2h4 mice develop spontaneous autoimmune thyroiditis (SAT) with chronic inflammation of thyroids by T and B cells. B-cell deficient (B(-/-) ) mice are resistant to SAT but develop SAT if regulatory T (Treg) cells are transiently depleted. We established a transfer model using splenocytes from CD28(-/-)  B(-/-) mice (effector cells and antigen-presenting cells) cultured with or without sorted Treg cells from Foxp3-GFP wild-type (WT) or B(-/-) mice. After transfer to mice lacking T cells, mice given Treg cells from B(-/-) mice had significantly lower SAT severity scores than mice given Treg cells from WT mice, indicating that Treg cells in B(-/-) mice are more effective suppressors of SAT than Treg cells in WT mice. Treg cells from B(-/-) mice differ from WT Treg cells in expression of CD27, tumour necrosis factor receptor (TNFR) II p75, and glucocorticoid-induced TNFR-related protein (GITR). After transient depletion using anti-CD25 or diphtheria toxin, the repopulating Treg cells in B(-/-) mice lack suppressor function, and expression of CD27, GITR and p75 is like that of WT Treg cells. If B(-/-) Treg cells develop with B cells in bone marrow chimeras, their phenotype is like that of WT Treg cells. Addition of B cells to cultures of B(-/-) Treg and T effector cells abrogates their suppressive function and their phenotype is like that of WT Treg cells. These results establish for the first time that Treg cells in WT and B(-/-) mice differ both functionally and in expression of particular cell surface markers. Both properties are altered after transient depletion and repopulation of B(-/-) Treg cells, and by the presence of B cells during Treg cell development or during interaction with effector T cells.

Rituximab therapy has a rapid and durable response for refractory cytopenia in childhood-onset systemic lupus erythematosus

Objectives

Autoimmune thrombocytopenia (AITP) and hemolytic anemia (AIHA) are common in childhood-onset systemic lupus erythematosus (cSLE) and may be refractory to conventional therapies. Our objectives were to: (a) examine our experience; (b) determine the rate and durability of response to rituximab; and (c) evaluate its safety in our cSLE population with refractory cytopenias.

Methods

We performed a single-center retrospective cohort study of cSLE patients with refractory AITP or AIHA treated with rituximab between 2003 and 2012. Outcomes included the time to complete clinical response, time to B-cell depletion, duration of response and time to flare. Adverse events were also analyzed.

Results

Twenty-four (6%) of 394 cSLE patients received rituximab for refractory cytopenia. The indication was AITP in 16 (67%), AIHA in five (21%) and both in three (13%) patients. The median (interquartile range (IQR)) time from cytopenia onset to rituximab therapy was 16 (7–27) months for AITP and 10 (2–29) months for AIHA. Complete response following the first course of rituximab occurred at a median (IQR) of 48 (14–103) days, only one patient failed to respond. Five (21%) patients had one or more flare episodes at 22 (15–27) months. Infusion reactions were rare and one infection with herpes zoster required hospitalization in the first 12 months. Three of four patients with low IgG levels prior to the first rituximab course developed persistent hypogammaglobulinemia, and three patients have required intravenous immunoglobulin replacement.

Conclusion

Rituximab appears to be a well-tolerated, safe and long-lasting therapy for cSLE patients with refractory AITP and/or AIHA. Caution should be exercised when considering rituximab for patients with preexisting hypogammaglobulinemia.

Rituximab and lupus--a promising pair?

Systemic lupus erythematosus (SLE) is a clinically diverse and potentially life-threatening auto-immune disease that can affect almost any organ system. Although much is still unknown regarding its pathogenesis, B cell abnormalities are thought to be central. A high relapse rate along with the toxicity associated with conventional treatments signify the need for more tailored approaches in this very heterogeneous disease. Both its mechanism targeting B cells and a relatively large number of case series and observational studies have suggested that the B cell-depleting agent rituximab could be a potent SLE drug. However, two randomized controlled trials failed to meet efficacy endpoints. Nevertheless, rituximab has continued to be used as an off-label alternative mainly in patients refractory to conventional immunosuppressive treatment. This article will review the current role of rituximab in SLE.

Increased Interleukin 21 and Follicular Helper T-like Cells and Reduced Interleukin 10+ B cells in Patients with New-onset Systemic Lupus Erythematosus

Objective.

To elucidate the potential role of follicular helper T cells (TFH) and interleukin 10 (IL-10)+ B cells in the development of systemic lupus erythematosus (SLE).

Methods.

The numbers of peripheral blood CD27+, CD38+, CD86+, CD95+, IL-10+ B cells, and inducible T cell costimulator (ICOS)+, programmed death-1 (PD-1)+, IL-21+, CXCR5+CD4+ TFH-like cells were examined in 23 patients with new onset SLE and 20 healthy controls (HC).

Results

In comparison with HC, significantly reduced numbers of CD19+ and IL-10+ B cells, but increased numbers of CD27high, CD86+, CD95+ B cells, CXCR5+CD4+, ICOS+, PD-1+, and IL-21+ TFH-like cells were detected, which were accompanied by higher levels of serum IL-21, but lower levels of IL-10 in the patients. Treatment with anti-SLE therapy modulated the imbalance of different subsets of B and TFH-like cells. The levels of serum IL-21 and IL-10 were positively correlated with the numbers of CD4+CXCR5+ TFH-like and CD19+CD5+CD1d+ B cells in the patients, respectively. The numbers of CD27high B cells were correlated positively with IL-21+ TFH-like cells, but negatively with IL-10+ B cells. The values of SLE Disease Activity Index, C3, and erythrocyte sedimentation rate were correlated positively with serum IL-21, but negatively with IL-10 in those patients.

Conclusion.

Our data indicate that the imbalance of IL-21+ TFH-like, CD27high, and IL-10+ B cells may be associated with the pathogenesis of SLE, and levels of serum IL-21 and IL-10 may be valuable for evaluating disease activity in SLE.

Naja naja atra Venom Protects against Manifestations of Systemic Lupus Erythematosus in MRL/lpr Mice

Systemic lupus erythematosus (SLE) is an autoimmune disease and effective therapy for this pathology is currently unavailable. We previously reported that oral administration of Naja naja atra venom (NNAV) had anti-inflammatory and immune regulatory actions. We speculated that NNAV may have therapeutic effects in MRL/lpr SLE mice. Twelve-week-old MRL/lpr mice received oral administration of NNAV (20, 40, and 80 μg/kg) or Tripterygium wilfordii polyglycosidium (10 mg/kg) daily for 16 weeks. The effects of NNAV on SLE manifestations, including skin erythema, proteinuria, and anxiety-like behaviors, were assessed with visual inspection and Multistix 8 SG strips and open field test, respectively. The pathology of spleen and kidney was examined with H&E staining. The changes in autoimmune antibodies and cytokines were determined with ELISA kits. The results showed that NNAV protected against the manifestation of SLE, including skin erythema and proteinuria. In addition, although no apparent histological change was found in liver and heart in MRL/lpr SLE mice, NNAV reduced the levels of glutamate pyruvate transaminase and creatine kinase. Furthermore, NNAV increased serum C3 and reduced concentrations of circulating globulin, anti-dsDNA antibody, and inflammatory cytokines IL-6 and TNF-α. NNAV also reduced lymphadenopathy and renal injury. These results suggest that NNAV may have therapeutic values in the treatment of SLE by inhibiting autoimmune responses.

Vitamin D levels in Jamaican patients with systemic lupus erythematosus

Vitamin D has important effects on the immune system as it has been shown to exert antiproliferative and relative immunosuppressant effects. Low levels of this hormone may contribute to the immune activation in systemic lupus erythematosus (SLE) and other autoimmune diseases. Serum levels of 25-OH vitamin D were measured in 75 patients with SLE in Jamaica, using an enzyme-linked immunoassay. Correlations with clinical data and disease activity as determined by the BILAG index were determined. Of a total of 75 patients, 33 (44%) had vitamin D sufficiency with mean vitamin D level of 39.45 ng/ml (range, 30.35-58.16). Forty-two (56%) patients had either vitamin D deficiency or insufficiency, 30 (40%) had vitamin D insufficiency, mean 26.36 ng/ml (range, 20.26-29.88), and 12 (16%) had vitamin D deficiency, mean 16.07 ng/ml (range, 7.78-19.90). There was an overall negative relationship between the total disease activity score using the BILAG index and vitamin D levels, and this was influenced primarily by the relationship seen among the vitamin D-deficient subgroup. This was also impacted on by a patient population that was significantly skewed toward low disease activity. The negative association trended toward statistical significance. Vitamin D deficiency is prevalent among patients with SLE in Jamaica. A relationship between low serum levels of vitamin D and SLE activity may occur.

Reduced B lymphoid kinase (Blk) expression enhances proinflammatory cytokine production and induces nephrosis in C57BL/6-lpr/lpr mice

BLK, which encodes B lymphoid kinase, was recently identified in genome wide association studies as a susceptibility gene for systemic lupus erythematosus (SLE), and risk alleles mapping to the BLK locus result in reduced gene expression. To determine whether BLK is indeed a bona fide susceptibility gene, we developed an experimental mouse model, namely the Blk^+/−.lpr/lpr (Blk^+/−.lpr) mouse, in which Blk expression levels are reduced to levels comparable to those in individuals carrying a risk allele. Here, we report that Blk is expressed not only in B cells, but also in IL-17-producing γδ and DN αβ T cells and in plasmacytoid dendritic cells (pDCs). Moreover, we found that solely reducing Blk expression in C57BL/6-lpr/lpr mice enhanced proinflammatory cytokine production and accelerated the onset of lymphoproliferation, proteinuria, and kidney disease. Together, these findings suggest that BLK risk alleles confer susceptibility to SLE through the dysregulation of a proinflammatory cytokine network.