Comparative time-series analyses of gut microbiome profiles in genetically and chemically induced lupus-prone mice and the impacts of fecal transplantation

Although the association between gut dysbiosis (imbalance of the microbiota) in systemic lupus erythematosus (SLE) is well-known, the simultaneous exploration in gut dysbiosis in fecal and different intestinal sections before and after lupus onset (at 2, 4, 6, 8, and 10 months old) resulting from the loss of inhibitory Fc gamma receptor IIb (FcGIIb) and pristane induction have never been conducted. Anti-dsDNA (an important lupus autoantibody) and proteinuria developed as early as 6 months old in both models, with higher levels in FcGRIIb deficient (FcGRIIb-/-) mice. Compared to the healthy control at 2 and 4 months, the lupus mice (both FcGRRIIb-/- and pristane) and healthy mice at 6 months old demonstrated an alteration as indicated by the Shannon alpha diversity index, highlighting influences of lupus- and age-induced dysbiosis, respectively. Non-metric multidimensional scaling (NMDS) revealed that the fecal microbiota of FcGRIIb-/- mice were distinct from the age-matched healthy control at all timepoints (at 6 month, p < 0.05), while pristane mice showed divergence at only some timepoints. Analyses of different intestinal sections revealed similarity among microbiota in the cecum, colon, and feces, contrasting with those in the small intestines (duodenum, jejunum, and ileum). Subtle differences were found between FcGRIIb-/- and pristane mice in feces and the intestinal sections as assessed by several analyses, for examples, the similar or dissimilar distances (NMDS), the neighbor-joining clustering, and the potential metabolisms (KEGG pathway analysis). Due to the differences between the gut microbiota (feces and intestinal sections) in the lupus mice and the healthy control, rebalancing of the microbiota using rectal administration of feces from the healthy control (fecal transplantation; FMT) to 7-month-old FcGIIb-/- mice (the established lupus; positive anti-dsDNA and proteinuria) was performed. In comparison to FcGRIIb-/- mice without FMT, FMT mice (more effect on the female than the male mice) showed the lower anti-dsDNA levels with similar fecal microbiome diversity (16s DNA gene copy number) and microbiota patterns to the healthy control. In conclusion, gut microbiota (feces and intestinal sections) of lupus mice (FcGRIIb-/- and pristane) diverged from the control as early as 4-6 months old, correlating with lupus characteristics (anti-dsDNA and proteinuria). The different gut microbiota in FcGRIIb-/- and pristane suggested a possible different gut microbiota in lupus with various molecular causes. Furthermore, FMT appeared to mitigate gut dysbiosis and reduce anti-dsDNA, supporting the benefit of the rebalancing gut microbiota in lupus, with more studies are warranted.

Deciphering Mechanisms, Prevention Strategies, Management Plans, Medications, and Research Techniques for Strokes in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune rheumatic condition characterized by an unpredictable course and a wide spectrum of manifestations varying in severity. Individuals with SLE are at an increased risk of cerebrovascular events, particularly strokes. These strokes manifest with a diverse range of symptoms that cannot be solely attributed to conventional risk factors, underscoring their significance among the atypical risk factors in the context of SLE. This complexity complicates the identification of optimal management plans and the selection of medication combinations for individual patients. This susceptibility is further complicated by the nuances of neuropsychiatric SLE, which reveals a diverse array of neurological symptoms, particularly those associated with ischemic and hemorrhagic strokes. Given the broad range of clinical presentations and associated risks linking strokes to SLE, ongoing research and comprehensive care strategies are essential. These efforts are critical for improving patient outcomes by optimizing management strategies and discovering new medications. This review aims to elucidate the pathological connection between SLE and strokes by examining neurological manifestations, risk factors, mechanisms, prediction and prevention strategies, management plans, and available research tools and animal models. It seeks to explore this medical correlation and discover new medication options that can be tailored to individual SLE patients at risk of stroke.

The Therapeutic Effects of Probiotic on Systemic Lupus Erythematosus in Lupus Mice Models: A Systematic Review

Increasing evidence suggests the beneficial immunomodulatory effects of probiotics can reduce inflammation in systemic lupus erythematosus (SLE). However, there is no summary of the existing evidence available. This study aims to investigate the therapeutic effects of probiotics on SLE in a lupus mouse model by examining various markers, including inflammatory cytokines, Treg cells, disease activity, and gut microbiota. A systematic search was conducted using three databases (Web of Science, PubMed, and Scopus) to identify animal studies that reported the therapeutic benefits of probiotics against SLE. Data extracted from the selected articles were qualitatively synthesized. The SYRCLE risk of bias tool was used to evaluate the risk of bias. Out of a total of 3205 articles, 12 met the inclusion criteria. Probiotic strains, quantities, and routes of administration varied among the studies. The treatment ranged from 8 to 47 weeks. Probiotic strains such as L. fermentum CECT5716, L. casei B255, L. reuteri DSM 17509, L. plantarum LP299v, and L. acidophilus can significantly reduce pro-inflammatory cytokines (TNF-α, IL-12, IL-6, IL-1β, IL-17, and IFN-γ) levels while increasing anti-inflammatory IL-10 and Treg cells. Probiotics also delay the production of autoantibodies, thus prolonging the remission period, decreasing flare frequency, and delaying disease progression. Furthermore, probiotic administration prevents gut dysbiosis, increases intestinal stability, and prevents pathogen colonization. In conclusion, probiotics can be considered a new alternative therapeutic approach for the management of SLE. Further clinical studies are required to investigate and validate the safety and effectiveness of probiotics in humans.

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.

Understanding the Current Landscape of Kidney Disease in Canada to Advance Precision Medicine Guided Personalized Care

Purpose of Review

To understand the impact of kidney disease in Canada and the priority areas of kidney research that can benefit from patient-oriented, precision medicine research using novel technologies.

Sources of Information

Information was collected through discussions between health care professionals, researchers, and patient partners. Literature was compiled using search engines (PubMed, PubMed central, Medline, and Google) and data from the Canadian Organ Replacement Register.

Methods

We reviewed the impact, prevalence, economic burden, causes of kidney disease, and priority research areas in Canada. After reviewing the priority areas for kidney research, potential avenues for future research that can integrate precision medicine initiatives for patient-oriented research were outlined.

Key Findings

Chronic kidney disease (CKD) remains among the top causes of morbidity and mortality in the world and exerts a large financial strain on the health care system. Despite the increasing number of people with CKD, funding for basic kidney research continues to trail behind other diseases. Current funding strategies favor existing clinical treatment and patient educational strategies. The identification of genetic factors for various forms of kidney disease in the adult and pediatric populations provides mechanistic insight into disease pathogenesis. Allocation of resources and funding toward existing high-yield personalized research initiatives have the potential to significantly affect patient-oriented research outcomes but will be difficult due to a constant decline of funding for kidney research.

Limitations

This is an overview primarily focused on Canadian-specific literature rather than a comprehensive systematic review of the literature. The scope of our findings and conclusions may not be applicable to health care systems in other countries.

Evaluation of the Therapeutic Potential of Mesenchymal Stem Cells (MSCs) in Preclinical Models of Autoimmune Diseases

Autoimmune diseases, chronic in nature, are generally hard to alleviate. Present long-term treatments with available drugs such as steroids, immune-suppressive drugs, or antibodies have several debilitating side effects. Therefore, new treatment options are urgently needed. Stem cells, in general, have the potential to reduce immune-mediated damage through immunomodulation and T cell regulation (T regs) by inhibiting the proliferation of dendritic cells and T and B cells and reducing inflammation through the generation of immunosuppressive biomolecules like interleukin 10 (IL-10), transforming growth factor-β (TGF-β), nitric oxide (NO), indoleamine 2,3-dioxygenase (IDO), and prostaglandin E2 (PGE2). Many stem cell-based therapeutics have been evaluated in the clinic, but the overall clinical outcomes in terms of efficacy and the longevity of therapeutic benefits seem to be variable and inconsistent with the postulated benefits. This emphasizes a greater need for building robust preclinical models and models that can better predict the clinical translation of stem cell-based therapeutics. Stem cell therapy based on MSCs having the definitive potential to regulate the immune system and control inflammation is emerging as a promising tool for the treatment of autoimmune disorders while promoting tissue regeneration. MSCs, derived from bone marrow, umbilical cord, and adipose tissue, have been shown to be highly immunomodulatory and anti-inflammatory and shown to enhance tissue repair and regeneration in preclinical models as well as in clinical settings. In this article, a review on the status of MSC-based preclinical disease models with emphasis on understanding disease mechanisms in chronic inflammatory disorders caused by exaggerated host immune response in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) was carried out. We also emphasized various factors that better predict the translation of stem cell therapeutic outcomes from preclinical disease models to human patients.

The Mango’s Mistletoe Leaves Extract Ameliorates Lupus by Inhibiting the Anti-dsDNA Antibody Production, the Percentages of CD8+CD28− and CD4+CD28− T Cells

BACKGROUND: In SLE patients, repeated antigen stimulations induce a progressive reduction in CD28 expression on the surface of T cells and the chronic inflammation condition. Mango’s mistletoe is a parasitic plant that has anti-inflammation, antiproliferation, and immunomodulatory activities. AIM: This study aimed to investigate the effect of mango’s mistletoe leaves extract (MLE) in inhibiting anti-dsDNA antibodies and ameliorating the percentages of CD8+CD28− and CD4+CD28− T cells in a pristane-induced lupus mice model. METHODS: Lupus induction was undertaken by an injection of pristane 0.5 ml intraperitoneally in 6–8-week-old female balb/c mice. Mice with lupus signs were grouped randomly into the treatment groups which received MLE at doses of 150, 300, and 600 mg/kgbw/d for 28 days, respectively, and the positive control group without MLE. On day 29, anti-dsDNA antibody levels were analyzed using an ELISA. One of the immunosenescence markers (CD28− T cells) was investigated using a flow cytometer. ANOVA test was used for statistical analysis. RESULTS: The mango’s mistletoe leaves extract (MLE) significantly decreased the number of anti-dsDNA antibodies (*p < 0.05), the percentages of CD8+CD28− T cells (*p < 0.05) and CD4+CD28− T cells (*p < 0.05). CONCLUSION: We resume that the mango’s mistletoe leaves can ameliorate lupus by inhibiting anti-dsDNA antibody production and the percentages of CD8+CD28− and CD4+CD28− T cells.

The effects of B-cell-activating factor on the population size, maturation and function of murine natural killer cells

The role of B-cell-activating factor (BAFF) in B-lymphocyte biology has been comprehensively studied, but its contributions to innate immunity remain unclear. Natural killer (NK) cells form the first line of defense against viruses and tumors, and have been shown to be defective in patients with systemic lupus erythematosus (SLE). The link between BAFF and NK cells in the development and progression of SLE remains unstudied. By assessing NK cell numbers in wild-type (WT), BAFF^-/- (BAFF deficient), BAFF-R^-/- (BAFF receptor deficient), TACI^-/- (transmembrane activator and calcium modulator and cyclophilin ligand interactor deficient), BCMA^-/- (B-cell maturation antigen deficient) and BAFF transgenic (Tg) mice, we observed that BAFF signaling through BAFF-R was essential for sustaining NK cell numbers in the spleen. However, according to the cell surface expression of CD27 and CD11b on NK cells, we found that BAFF was dispensable for NK cell maturation. Ex vivo and in vivo models showed that NK cells from BAFF^-/- and BAFF Tg mice produced interferon-γ and killed tumor cells at a level similar to that in WT mice. Finally, we established that NK cells do not express receptors that interact with BAFF in the steady state or in the BAFF Tg mouse model of SLE. Our findings demonstrate that BAFF has an indirect effect on NK cell homeostasis and no effect on NK cell function.

Anti-ANX A1 Antibody Therapy in MRL/lpr Murine Model of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a severe autoimmune disease characterized by dysfunction of immune regulation, overproduction of inflammatory cytokines and attack on normal tissues by self-reactive cells and antibodies. The main role in the pathogenesis plays the autoreactive tandem of B-T cells, responsible for lupus progression and acceleration. Both activated B and T cells express a phospholipid binding protein Annexin A1 and abnormal levels of the protein were found in murine and human autoimmune syndromes, potentiating its role as a therapeutic target. Here, using anti-annexin A1 antibody we explore its property to modulate the autoimmune response in MRL/lpr mouse model of lupus. Anti-ANX A1 antibody was tested in vitro using spleen cells from MRL/lpr mice to determine the effect on lymphocyte activation, plasma cells differentiation, apoptosis and proliferation by flow cytometry and ELISpot assays. Subsequently, several groups of young (disease-free) and old (sick) MRL/lpr mice were treated with the antibody to determine the levels of panel auto-antibodies and cytokines, T cell arrest and migration. Treatment of splenocytes with anti-ANX A1 antibody inhibited T-cell activation and proliferation, suppressed anti-dsDNA antibody-producing plasma cells and affected B cell apoptosis. Administration of the antibody to MRL/lpr mice resulted to decreased autoantibody levels to various lupus antigens, suppressed T cell migration from lymph nodes and increased the levels of IL4 mRNA compared to the control group. Anti-ANX A1 antibody therapy suppresses B and T cell over-activation and down- modulates disease activity.

An evaluation of a novel nanoformulation of imatinib mesylate in a mouse model of lupus nephritis

Studies have suggested imatinib mesylate (ImM) as a potential treatment for systemic lupus erythematosus nephritis (SLEN). However, ImM has limited renal excretion. The goal of the current research was to develop an ImM containing nanoformulation, conduct studies to evaluate pharmacokinetics, and determine whether kidney deposition can be enhanced in a mouse model of SLEN. A fish oil-based ImM oil-in-water nanoemulsion was developed and characterized for particle size, zeta potential, pH, and stability. MRL/MpJ-Faslrp (model of SLEN) and MRL/MpJ (control) mice (12-13 weeks) received one dose of ImM as either a nanoemulsion or naked drug. Pharmacokinetics and kidney deposition studies were performed. Statistics were conducted with a student's T-test. The nanoemulsion characteristics included particle size range of 60-80 nm, zeta potential of -6.6 to -7.8 mV, polydispersity index < 0.3, 3-day stability at 4 °C, and limited ImM leakage from the nanoemulsion in serum. Pharmacokinetics of the nanoformulation showed changes to pharmacokinetic parameters suggesting reduced systemic exposures (with reduced potential for toxicities) to ImM. Kidney deposition of ImM was threefold higher after 4 h in the MRL/MpJ-Faslrp mice that received the nanoformulation vs. naked drug. The current study showed encouraging results for development of a stable and well-characterized nanoemulsion for optimizing kidney deposition of ImM. Future strategies will define dose-efficacy and dose-toxicity relationships and evaluate approaches to further enhance kidney delivery and optimize deposition to the mesangial location of the kidney.

Genetic and molecular biology of systemic lupus erythematosus among Iranian patients: an overview

BACKGROUND

Systemic lupus erythematosus (SLE) is a clinicopathologically heterogeneous chronic autoimmune disorder affecting different organs and tissues. It has been reported that there is an increasing rate of SLE incidence among Iranian population. Moreover, the Iranian SLE patients have more severe clinical manifestations compared with other countries. Therefore, it is required to introduce novel methods for the early detection of SLE in this population. Various environmental and genetic factors are involved in SLE progression.

MAIN BODY

In present review we have summarized all of the reported genes which have been associated with clinicopathological features of SLE among Iranian patients.

CONCLUSIONS

Apart from the reported cytokines and chemokines, it was interestingly observed that the apoptosis related genes and non-coding RNAs were the most reported genetic abnormalities associated with SLE progression among Iranians. This review clarifies the genetics and molecular biology of SLE progression among Iranian cases. Moreover, this review paves the way of introducing an efficient panel of genetic markers for the early detection and better management of SLE in this population.

Interleukin 4 deficiency limits the development of a lupus-like disease in mice triggered by phospholipids in a non-bilayer arrangement

Non-bilayer phospholipids arrangements (NPAs) are transient molecular associations different from lipid bilayers. When they become stable, they can trigger a disease in mice resembling human lupus, which is mainly characterized by the production of anti-NPA IgG antibodies. NPAs are stabilized on liposomes or cell bilayers by the drugs procainamide or chlorpromazine, which produce drug-induced lupus in humans. Here, we evaluated the participation of the T_H 2 response, through its hallmark cytokine IL-4, on the development of the lupus-like disease in mice. Wild-type or IL-4 knockout BALB/c mice received liposomes bearing drug-induced NPAs, the drugs alone, or an anti-NPA monoclonal antibody (H308) to induce the lupus-like disease (the last two procedures stabilize NPAs on mice cells). IL-4 KO mice showed minor disease manifestations, compared to wild-type mice, with decreased production of anti-NPA IgG antibodies, no anti-cardiolipin, anti-histones and anticoagulant antibodies, and no kidney or skin lesions. In these mice, H308 was the only inducer of anti-NPA IgG antibodies. These findings indicate that IL-4 has a central role in the development of the murine lupus-like disease induced by NPA stabilization.

Punicalagin Ameliorates Lupus Nephritis via Inhibition of PAR2

Lupus nephritis (LN) is the most frequent phenotype in patients with systemic lupus erythematosus (SLE) and has a high rate of progression to end-stage renal disease, in spite of intensive treatment and maintenance therapies. Recent evidence suggests that protease-activated receptor-2 (PAR2) is a therapeutic target for glomerulonephritis. In this study, we performed a cell-based high-throughput screening and identified a novel potent PAR2 antagonist, punicalagin (PCG, a major polyphenol enriched in pomegranate), and evaluated the effects of PCG on LN. The effect of PCG on PAR2 inhibition was observed in the human podocyte cell line and its effect on LN was evaluated in NZB/W F1 mice. In the human podocyte cell line, PCG potently inhibited PAR2 (IC₅₀ = 1.5 ± 0.03 µM) and significantly reduced the PAR2-mediated activation of ERK1/2 and NF-κB signaling pathway. In addition, PCG significantly decreased PAR2-induced increases in ICAM-1 and VCAM-1 as well as in IL-8, IFN-γ, and TNF-α expression. Notably, the intraperitoneal administration of PCG significantly alleviated kidney injury and splenomegaly and reduced proteinuria and renal ICAM-1 and VCAM-1 expression in NZB/W F1 mice. Our results suggest that PCG has beneficial effects on LN via inhibition of PAR2, and PCG is a potential therapeutic agent for LN.

Monoclonal antibody therapy that targets phospholipid-binding protein delays lupus activity in MRL/lpr mice

Systemic lupus erythematosus is an autoimmune syndrome characterized by the development of autoantibodies to a wide range of antigens. Together with B cells, respective self-reactive T cells have an important contribution in disease progression as being responsible for inflammatory cytokines secretion, B cell activation and promoting amplification of the autoimmune response. Annexin A1 is expressed by many cell types and binds to phospholipids in a Ca²⁺ -dependent manner. Abnormal expression of annexin A1 was found on activated B and T cells in both murine and human autoimmunity suggesting its potential role as a therapeutic target. In the present study, we have investigated the possibility to suppress autoimmune manifestation in spontaneous mouse model of lupus using anti-annexin A1 antibody. Groups of lupus-prone MRL/lpr mice were treated with the anti-annexin A1 monoclonal antibody, and the disease activity and survival of the animals were following up. Flow cytometry, ELISA assays, and histological and immunofluorescence kidney analyses were used to determine the levels of Annexin A1 expression, cytokines, anti-dsDNA antibodies and kidney injuries. The administration of this monoclonal antibody to MRL/lpr mice resulted in suppression of IgG anti-dsDNA antibody production, modulated IL-10 secretion, decreased disease activity and prolonged survival compared with the control group.

PEPITEM/Cadherin 15 Axis Inhibits T Lymphocyte Infiltration and Glomerulonephritis in a Mouse Model of Systemic Lupus Erythematosus

Control of lymphocyte infiltration in kidney is a potential therapeutic strategy for lupus nephritis, considering that control of lymphocyte migration by sphingosine 1 phosphate has been implicated in inflammation-related pathology. The peptide inhibitor of the transendothelial migration (PEPITEM)/cadherin (CDH) 15 axis was recently reported to promote sphingosine 1 phosphate secretion. In this study, we investigated whether CDH15 is expressed in the kidney of MRL/lpr mice and whether lymphocyte infiltration is suppressed by exogenously administered PEPITEM. Mice (18 wk old) were randomized into 4-wk treatment groups that received PEPITEM or PBS encapsulated in dipalmitoylphosphatidylcholine liposomes. Enlargement of the kidney, spleen, and axillary lymph nodes was suppressed by PEPITEM treatment, which also blocked infiltration of double-negative T lymphocytes into the kidney and glomerular IgG/C3 deposition, reduced proteinuria, and increased podocyte density. Immunohistochemical analysis revealed that the PEPITEM receptor CDH15 was expressed on vascular endothelial cells of glomeruli and kidney arterioles, skin, and peritoneum in lupus mice at 22 wk of age but not in 4-wk-old mice. These results suggest that PEPITEM inhibits lymphocyte migration and infiltration into the kidney, thereby preserving the kidney structure and reducing proteinuria. Thus, PEPITEM administration may be considered as a potential therapeutic tool for systemic lupus erythematosus.

Leaky-gut enhanced lupus progression in the Fc gamma receptor-IIb deficient and pristane-induced mouse models of lupus

The influence of gut-leakage or gut-microbiota upon lupus progression was explored in 2 lupus mouse models. Pristane, administered in 4-wk-old wild-type (WT) female mice, induced lupus characteristics at 24-wk-old similar to the lupus-onset in FcGRIIb−/− mice. Gut-microbiota alteration was induced by co-housing together with the gavage of feces from 40-wk-old FcGRIIb−/− mice (symptomatic lupus). On the other hand,  gut-leakage was induced  by dextran sulfate solution (DSS). DSS and gut-microbiota alteration induced high serum anti-dsDNA immunoglobulin (Ig) as early as 30 days post-DSS only in FcGRIIb−/− mice. DSS, but not gut-microbiota alteration, enhanced lupus characteristics (serum creatinine and proteinuria) in both lupus models (but not in WT) at 60 days post-DSS. Indeed, DSS induced the translocation of molecular components of gut-pathogens as determined by bacterial burdens in mesenteric lymph node (MLN), endotoxemia (gut-bacterial molecule) and serum (1→3)-β-D-glucan (BG) (gut-fungal molecule) as early as 15 days post-DSS together with enhanced MLN apoptosis in both WT and lupus mice. However, DSS induced spleen apoptosis in FcGRIIb−/− and WT mice at 30 and 60 days post-DSS, respectively, suggesting the higher impact of gut-leakage against spleen of lupus mice. In addition, macrophages preconditioning with LPS plus BG were susceptible to starvation-induced apoptosis, predominantly in FcGRIIb−/− cell, implying the influence of gut-leakage upon cell stress. In summary, gut-leakage induced gut-translocation of organismal-molecules then enhanced the susceptibility of stress-induced apoptosis, predominantly in lupus. Subsequently, the higher burdens of apoptosis in lupus mice increased anti-dsDNA Ig and worsen lupus severity through immune complex deposition. Hence, therapeutic strategies addressing gut-leakage in lupus are interesting.

Immune Relevant and Immune Deficient Mice: Options and Opportunities in Translational Research

In 1989 ILAR published a list and description of immunodeficient rodents used in research. Since then, advances in understanding of molecular mechanisms; recognition of genetic, epigenetic microbial, and other influences on immunity; and capabilities in manipulating genomes and microbiomes have increased options and opportunities for selecting mice and designing studies to answer important mechanistic and therapeutic questions. Despite numerous scientific breakthroughs that have benefitted from research in mice, there is debate about the relevance and predictive or translational value of research in mice. Reproducibility of results obtained from mice and other research models also is a well-publicized concern. This review summarizes resources to inform the selection and use of immune relevant mouse strains and stocks, aiming to improve the utility, validity, and reproducibility of research in mice. Immune sufficient genetic variations, immune relevant spontaneous mutations, immunodeficient and autoimmune phenotypes, and selected induced conditions are emphasized.

Noncanonical immunomodulatory activity of complement regulator C4BP(β-) limits the development of lupus nephritis

Lupus nephritis is a chronic autoimmune-inflammatory condition that can lead to end-stage kidney disease. Presently available immunosuppressive treatments for lupus nephritis are suboptimal and can induce significant side effects. Recently, we characterized a novel immunomodulatory activity of the minor isoform of the classical pathway complement inhibitor, C4BP(β-). We show here that C4BP(β-) treatment prevented the development of proteinuria and albuminuria, decreased significantly the formation of anti-dsDNA antibodies and, locally, mitigated renal glomerular IgG and C3 deposition and generation of apoptotic cells. There was a consequent histological improvement and increased survival in lupus-prone mice. The therapeutic efficacy of C4BP(β-) was analogous to that of the broad-acting immunosuppressant cyclophosphamide. Remarkably, a comparative transcriptional profiling analysis revealed that the kidney gene expression signature resulting from C4BP(β-) treatment turned out to be 10 times smaller than that induced by cyclophosphamide treatment. C4BP(β-) immunomodulation induced significant downregulation of transcripts relevant to lupus nephritis indicating immunopathogenic cell infiltration, including activated T cells (Lat), B cells (Cd19, Ms4a1, Tnfrsf13c), inflammatory phagocytes (Irf7) and neutrophils (Prtn3, S100a8, S100a9). Furthermore, cytokine profiling and immunohistochemistry confirmed that C4BP(β-), through systemic and local CXCL13 downregulation, was able to prevent ectopic lymphoid structures neogenesis in aged mice with lupus nephritis. Thus, due to its anti-inflammatory and immunomodulatory activities and high specificity, C4BP(β-) could be considered for further clinical development in patients with systemic lupus erythematosus.

BAFF inhibition in SLE-Is tolerance restored?

The B cell activating factor (BAFF) inhibitor, belimumab, is the first biologic drug approved for the treatment of SLE, and exhibits modest, but durable, efficacy in decreasing disease flares and organ damage. BAFF and its homolog APRIL are TNF-like cytokines that support the survival and differentiation of B cells at distinct developmental stages. BAFF is a crucial survival factor for transitional and mature B cells that acts as rheostat for the maturation of low-affinity autoreactive cells. In addition, BAFF augments innate B cell responses via complex interactions with the B cell receptor (BCR) and Toll like receptor (TLR) pathways. In this manner, BAFF impacts autoreactive B cell activation via extrafollicular pathways and fine tunes affinity selection within germinal centers (GC). Finally, BAFF and APRIL support plasma cell survival, with differential impacts on IgM- and IgG-producing populations. Therapeutically, BAFF and combined BAFF/APRIL inhibition delays disease onset in diverse murine lupus strains, although responsiveness to BAFF inhibition is model dependent, in keeping with heterogeneity in clinical responses to belimumab treatment in humans. In this review, we discuss the mechanisms whereby BAFF/APRIL signals promote autoreactive B cell activation, discuss whether altered selection accounts for therapeutic benefits of BAFF inhibition, and address whether new insights into BAFF/APRIL family complexity can be exploited to improve human lupus treatments.

Belimumab alters transitional B-cell subset proportions in patients with stable systemic lupus erythematosus

OBJECTIVE

We evaluated the effects of the B-cell activating factor (BAFF)-targeting antibody Belimumab on human nonmemory B-cell pools. Human B-cell pools were identified using surface markers adapted from mouse studies that specifically assessed reductions in immature B cells due to BAFF depletion. Patients with systemic lupus erythematosus (SLE) have high levels of both BAFF and immature B cells. Mechanistic mouse studies provide a framework for understanding human responses to therapies that target B cells.

METHODS

Peripheral blood mononuclear cells were isolated from healthy donors and SLE patients on Belimumab or standard-of-care therapy (SCT). Cells were stained for flow cytometry to identify B-cell subsets based on CD21/CD24. Differences in subset proportions were determined by one-way ANOVA and Tukey's post hoc test.

RESULTS

Patients treated with Belimumab show alterations in the nonmemory B-cell pool characterized by a decrease in the Transitional 2 (T2) subset (p = 0.002), and an increase in the proportion of Transitional 1 (T1) cells (p = 0.005) as compared with healthy donors and SCT patients. The naïve B-cell compartment showed no significant differences between the groups (p = 0.293).

CONCLUSION

Using a translational approach, we show that Belimumab-mediated BAFF depletion reduces the T2 subset in patients, similar to observations in mouse models with BAFF depletion.

PAM3 supports the generation of M2-like macrophages from lupus patient monocytes and improves disease outcome in murine lupus

Systematic Lupus Erythematosus (SLE) is an autoimmune syndrome of unclear etiology. While T and B cell abnormalities contribute to disease pathogenesis, recent work suggests that inflammatory M1-like macrophages also play a role. Previous work showed that the TLR2/1 agonist PAM3CSK4 (PAM3) could stimulate normal human monocytes to preferentially differentiate into immunosuppressive M2-like rather than inflammatory M1-like macrophages. This raised the possibility of PAM3 being used to normalize the M1:M2 ratio in SLE. Consistent with that possibility, monocytes from lupus patients differentiated into M2-like macrophages when treated with PAM3 in vitro. Furthermore, lupus-prone NZB x NZW F1 mice responded similarly to weekly PAM3 treatment. Normalization of the M2 macrophage frequency was associated with delayed disease progression, decreased autoantibody and inflammatory cytokine synthesis, reduced proteinuria and prolonged survival in NZB x NZW F1 mice. The ability of PAM3 to bias monocyte differentiation in favor of immunosuppressive macrophages may represent a novel approach to the therapy of SLE.

Increased susceptibility against Cryptococcus neoformans of lupus mouse models (pristane-induction and FcGRIIb deficiency) is associated with activated macrophage, regardless of genetic background

The severity of cryptococcosis in lupus from varying genetic-backgrounds might be different due to the heterogeneity of lupus-pathogenesis. This study explored cryptococcosis in lupus mouse models of pristane-induction (normal genetic-background) and FcGRIIb deficiency (genetic defect). Because the severity of lupus nephritis, as determined by proteinuria and serum creatinine, between pristane and FcGRIIb-/- mice were similar at 6-month-old, Cryptococcus neoformans was intravenously administered in 6-month-old mice and were age-matched with wild-type. Indeed, the cryptococcosis disease severity, as evaluated by mortality rate, internal-organ fungal burdens and serum cytokines, between pristane and FcGRIIb-/- mice was not different. However, the severity of cryptococcosis in wild-type was less severe than the lupus mice. On the other hand, phagocytosis activity of peritoneal macrophages from lupus mice (pristane and FcGRIIb-/-) was more predominant than the wild-type without the difference in macrophage killing-activity among these groups. In addition, the number of active T helper cells (Th-cell) in the spleen, including Th-cells with intracellular IFN-γ, from lupus mice (pristane and FcGRIIb-/-) was higher than wildtype. Moreover, these active Th-cells were even higher after 2 weeks of cryptococcal infection. These data support enhanced macrophage activation through prominent Th-cells in both lupus models. In conclusion, an increased susceptibility of cryptococcosis in both lupus models was independent to genetic background. This might due to Th-cell enhanced macrophage phagocytosis with the interference of macrophage killing activity from Cryptococcal immune-evasion properties.

Soluble MHC class II-driven therapy for a systemic lupus erythematosus murine experimental in vitro and in vivo model

Taking into consideration the multiparametric nature of systemic lupus erythematosus (SLE), the severity and variability of symptoms and the lack of effective therapeutic approaches, this study took advantage of the recently described role of soluble major histocompatibility complex class II (sMHCII) molecules in maintaining tolerance to the organism and attempted to apply sMHCII proteins as a treatment to murine SLE experimental models in vitro as well as in vivo. After breaking tolerance to DNA in vitro, which was accompanied by development of specific anti-dsDNA antibodies, syngeneic or allogeneic sMHCII molecules, purified from healthy mouse serum, could significantly reduce the specific antibody levels and drive the system towards immunosuppression, as assessed by specific marker analysis on T cells and cytokine production by flow cytometry and ELISA, respectively. The in vivo experimental model consisted of pristane-induced SLE symptoms to BALB/c mice, which developed maximal levels of anti-dsDNA 2 months after pristane inoculation. Syngeneic or allogeneic sMHCII administration could alleviate pristane-induced symptoms, significantly decrease specific anti-dsDNA antibody production and develop immunosuppression to the host, as manifested by increase of CD4 + CTLA-4 +  and CD4 + CD25 +  cell populations in the spleen. Thus, the results presented in this study introduced the ability of sMHCII proteins to suppress specific autoantigen response, opening new areas of research and offering novel therapeutic approaches to SLE with expanding features to other autoimmune diseases.

Delayed onset of autoreactive antibody production and M2-skewed macrophages contribute to improved survival of TACI deficient MRL-Fas/Lpr mouse

Anti-B cell activating factor belonging to TNF-family (BAFF) antibody therapy is indicated for the treatment of patients with active systemic lupus erythematosus (SLE). We hypothesized that the BAFF receptor, transmembrane activator and calcium-modulator and cyclophilin interactor (TACI) may be responsible for the generation of antibody secreting plasma cells in SLE. To test this hypothesis, we generated TACI deficient MRL-Fas/Lpr (LPR-TACI−/−) mouse. TACI deficiency resulted in improved survival of MRL-Fas/Lpr mice and delayed production of anti-dsDNA and anti-SAM/RNP antibodies. There was also a delay in the onset of proteinuria and the accumulation of IgG and inflammatory macrophages (Mϕs) in the glomeruli of young LPR-TACI−/− mice compared to wild-type mice. Underscoring the role of TACI in influencing Mϕ phenotype, the transfer of Mϕs from 12-week-old LPR-TACI−/− mice to age-matched sick wild-type animals led to a decrease in proteinuria and improvement in kidney pathology. The fact that, in LPR-TACI−/− mouse a more pronounced delay was in IgM and IgG3 autoreactive antibody isotypes and the kinetics of follicular helper T (Tfh) cell-development was comparable between the littermates suggest a role for TACI in T cell-independent autoantibody production in MRL-Fas/Lpr mouse prior to the onset of T cell-dependent antibody production.

Association of long non-coding RNA GAS5 and miR-21 levels in CD4+ T cells with clinical features of systemic lupus erythematosus

The present study aimed to assess the expression of growth arrest-specific 5 (GAS5) and microRNA (miR)-21 in systemic lupus erythematosus (SLE), and attempted to explore their association with clinical features. CD4⁺ T cells were isolated from peripheral blood of healthy donors and SLE patients by magnetic-activated cell sorting. GAS5 and miR-21 expression levels in cluster of differentiation (CD)4⁺ T cells were measured by reverse-transcription quantitative polymerase chain reaction. The results revealed that GAS5 and miR-21 levels were significantly elevated in CD4⁺ T cells of patients with SLE compared with those in control subjects (P<0.05). Regarding clinical features, SLE patients with ulceration had higher GAS5 expression levels in CD4⁺ T cells than those without ulceration (P<0.05), and the expression of miR-21 was significantly higher in CD4⁺ T cells of SLE patients with low levels of complement component 3 (C3) than in those with normal levels of complement C3 (P<0.05). In conclusion, GAS5 and miR-21 in CD4⁺ T cells may serve as potential biomarkers for the diagnosis and monitoring of the progression of SLE.

HM71224, a selective Bruton's tyrosine kinase inhibitor, attenuates the development of murine lupus

Background

Systemic lupus erythematosus (SLE) is associated with B cell hyperactivity, and lupus nephritis (LN), in particular, is promoted by the production of autoantibodies and immune complex deposition. Bruton’s tyrosine kinase (BTK) plays critical roles in B cell receptor-related and Fc receptor-related signaling. We aimed to investigate the impact of therapeutic intervention with HM71224 (LY3337641), a selective BTK inhibitor, on the development of murine SLE-like disease features.

Methods

We examined the therapeutic effects of HM71224 on SLE-like disease features in MRL/lpr and NZB/W F1 mice. The disease-related skin lesion was macroscopically observed in MRL/lpr mice, and the impact on splenomegaly and lymphadenopathy was determined by the weight of the spleen and cervical lymph node. The renal function was evaluated by measuring blood urea nitrogen, serum creatinine, and urine protein, and the renal damage was assessed by histopathological grading. Survival rate was observed during the administration period. The impact of B cell inhibition was investigated in splenocytes from both mice using flow cytometry. Autoantibody was measured in serum by ELISA.

Results

HM71224 effectively suppressed splenic B220⁺GL7⁺, B220⁺CD138⁺, and B220⁺CD69⁺ B cell counts, and anti-dsDNA IgG and reduced splenomegaly and lymph node enlargement. The compound also prevented skin lesions caused by lupus development, ameliorated renal inflammation and damage with increased blood urea nitrogen and creatinine, and decreased proteinuria. Furthermore, HM71224 also decreased mortality from lupus development in both mouse models.

Conclusion

Our results indicate that inhibition of BTK by HM71224 effectively reduced B cell hyperactivity and significantly attenuated the development of SLE and LN in rodent SLE models.

Vitamin D3 Alters the Expression of Toll-like Receptors in Peripheral Blood Mononuclear Cells of Patients With Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by production of inflammatory cytokines and autoreactive antibodies due to the loss of immune tolerance. Recognition of self-nucleic acids by intracellular Toll-like receptors (TLRs) can overactivate immune responses and this abnormal activation of TLRs contributes to the pathogenesis of the disease. In recent years, anti-inflammatory and immunomodulatory effects of 1,25-dihydroxyvitamin D3 (VitD3) on the immune system has received particular attention. The present study investigated the effects of vitamin D3 on the expression of TLR3, TLR7, and TLR9 in SLE patients. Study participants included 20 SLE patients and 20 age- and sex-matched healthy controls. Peripheral blood mononuclear cells (PBMCs) were isolated and cultured in the presence or absence of vitamin D3 (50 nM). Then RNA was extracted, cDNA was synthesized and gene expression levels of TLR3, TLR7, and TLR9 were assessed using real-time PCR. Up-regulated expression levels of TLR7 and TLR9 were observed in the PBMCs of SLE patients in comparison with controls. Culturing PBMCs with vitamin D3 significantly down-regulated the expression of TLR3 (8.86 ± 4.2 for SLE patients vs. 45.34 ± 18.6 for control; P = 0.03), TLR7 (17.91 ± 7.7 for SLE patients vs. 242.37 ± 89.6 for controls; P = 0.0001) and TLR9 (4.67 ± 1.9 for SLE patients vs. 8.9 ± 1.5 for controls; P = 0.007) in SLE patients in comparison with healthy controls. The results of the current study suggest that vitamin D3 could exert some of its immunomodulatory effects in SLE patients via affecting the expression levels of some TLRs. J. Cell. Biochem. 118: 4831-4835, 2017. © 2017 Wiley Periodicals, Inc.

Characterization of a PRISTANE-induced lupus-associated model in the non-human primate cynomolgus monkey

BACKGROUND

Lupus is an autoimmune disease with complex syndrome. Rodent models have limitations for recapitulating the spectrum of the disease. A more powerful translational model is desirable.

METHOD

Lupus-associated model in cynomolgus monkeys was induced by two intraperitoneal injections of 2, 6, 10, 14-tetramethylpentadecane (PRISTANE). Lupus-specific biomarkers and manifestations over a 246-day period were observed at multilevel. To visualize and quantify kidney function in real time, contrast-enhanced ultrasound was used.

RESULTS

The indicative biomarkers and manifestations fulfilled major diagnosis criteria according to the "Criteria of Lupus" of the American College of Rheumatology. Significant changes in time-intensity curve parameters were observed, indicating impaired renal function and the method as a feasible, non-invasive diagnostic method in primate model.

CONCLUSIONS

We successfully induced lupus-associated model with systemic lupus syndrome. This primate model can be a valuable translational model for further pathogenesis and symptomology studies and for exploring therapeutic candidates.

P-Selectin preserves immune tolerance in mice and is reduced in human cutaneous lupus

Mice deficient in P-Selectin presented altered immunity/tolerance balance. We have observed that the absence of P-Selectin promotes splenomegaly with reduced naïve T cell population, elevated activated/effector T cell subset, increased germinal center B and Tfh populations and high production of autoreactive antibodies. Moreover, 1.5-3-month-old P-selectin KO mice showed reduced IL-10-producing leukocytes in blood and a slightly reduced Treg population in the skin. With aging and, coinciding with disease severity, there is an increase in the IL17⁺ circulating and dermal T cell subpopulations and reduction of dermal Treg. As a consequence, P-Selectin deficient mice developed a progressive autoimmune syndrome showing skin alterations characteristic of lupus prone mice and elevated circulating autoantibodies, including anti-dsDNA. Similar to human SLE, disease pathogenesis was characterized by deposition of immune complexes in the dermoepidermal junction and renal glomeruli, and a complex pattern of autoantibodies. More important, skin biopsies of cutaneous lupus erythematosus patients did not show increased expression of P-Selectin, as described for other inflammatory diseases, and the number of vessels expressing P-Selectin was reduced.

Mesenchymal stem cell transplantation can restore lupus disease-associated miRNA expression and Th1/Th2 ratios in a murine model of SLE

C3.MRL-Fas^lpr/J mice spontaneously develop high titers of anti-dsDNA, mild glomerular nephritis, and severe lymphoproliferation symptoms. This study aimed to compare the effects of long-term serial administration of human adipose tissue-derived mesenchymal stem cells (ASCs), and cyclophosphamide treatment in C3.MRL-Fas^lpr/J mice using a murine SLE model. C3.MRL-Fas^lpr/J mice were divided into saline (C), cyclophosphamide (Y), and ASC (H) treatment groups. Background-matched control C3H mice treated with saline (N) were also compared. The Y group showed the greatest improvement in disease parameters, but with damaged trabecular integrity. ASC transplantation reduced anti-dsDNA levels, glomerular C3 deposition and CD138 proportion significantly, without trabecular damage. Furthermore, both cyclophosphamide and ASC treatment significantly decreased the ratio of Th1/Th2 compared with the saline-treatment. The expression levels of miR-31-5p, miR-96-5p, miR-182-5p, miR-183-5p, and miR-379-5p were significantly higher, while those of miR150-5p were significantly lower in the C group than in the N group. The expression levels of miR-96-5p, miR-182-5p in the Y and H groups were significantly lower than in the C group. Thus, treatment with cyclophosphamide or ASC can change miRNAs and decrease miR-96-5p and miR-182-5p expression, as well as decreasing the CD138 proportion and the Th1/Th2 ratio, which might be involved in the therapeutic mechanism.

Methods for Testing Immunological Factors

Hypersensitivity reactions can be elicited by various factors: either immunologically induced, i.e., allergic reactions to natural or synthetic compounds mediated by IgE, or non-immunologically induced, i.e., activation of mediator release from cells through direct contact, without the induction of, or the mediation through immune responses. Mediators responsible for hypersensitivity reactions are released from mast cells. An important preformed mediator of allergic reactions found in these cells is histamine. Specific allergens or the calcium ionophore 48/80 induce release of histamine from mast cells. The histamine concentration can be determined with the o-phthalaldehyde reaction.

Nonbilayer Phospholipid Arrangements Are Toll-Like Receptor-2/6 and TLR-4 Agonists and Trigger Inflammation in a Mouse Model Resembling Human Lupus

Systemic lupus erythematosus is characterized by dysregulated activation of T and B cells and autoantibodies to nuclear antigens and, in some cases, lipid antigens. Liposomes with nonbilayer phospholipid arrangements induce a disease resembling human lupus in mice, including IgM and IgG antibodies against nonbilayer phospholipid arrangements. As the effect of these liposomes on the innate immune response is unknown and innate immune system activation is necessary for efficient antibody formation, we evaluated the effect of these liposomes on Toll-like receptor (TLR) signaling, cytokine production, proinflammatory gene expression, and T, NKT, dendritic, and B cells. Liposomes induce TLR-4- and, to a lesser extent, TLR-2/TLR-6-dependent signaling in TLR-expressing human embryonic kidney (HEK) cells and bone marrow-derived macrophages. Mice with the lupus-like disease had increased serum concentrations of proinflammatory cytokines, C3a and C5a; they also had more TLR-4-expressing splenocytes, a higher expression of genes associated with TRIF-dependent TLR-4-signaling and complement activation, and a lower expression of apoptosis-related genes, compared to healthy mice. The percentage of NKT and the percentage and activation of dendritic and B2 cells were also increased. Thus, TLR-4 and TLR-2/TLR-6 activation by nonbilayer phospholipid arrangements triggers an inflammatory response that could contribute to autoantibody production and the generation of a lupus-like disease in mice.

Significantly reduced lymphadenopathy, salivary gland infiltrates and proteinuria in MRL-lpr/lpr mice treated with ultrasoluble curcumin/turmeric: increased survival with curcumin treatment

Objectives

Commercial curcumin (CU), derived from food spice turmeric (TU), has been widely studied as a potential therapeutic for a variety of oncological and inflammatory conditions. Lack of solubility/bioavailability has hindered curcumin's therapeutic efficacy in human diseases. We have solubilised curcumin in water applying heat/pressure, obtaining up to 35-fold increase in solubility (ultrasoluble curcumin (UsC)). We hypothesised that UsC or ultrasoluble turmeric (UsT) will ameliorate systemic lupus erythematosus (SLE) and Sjögren's syndrome (SS)-like disease in MRL-lpr/lpr mice.

Methods

Eighteen female MRL-lpr/lpr (6 weeks old) and 18 female MRL-MpJ mice (6 weeks old) were used. Female MRL-lpr/lpr mice develop lupus-like disease at the 10th week and die at an average age of 17 weeks. MRL-MpJ mice develop lupus-like disease around 47 weeks and typically die at 73 weeks. Six mice of each strain received autoclaved water only (lpr-water or MpJ-water group), UsC (lpr-CU or MpJ-CU group) or UsT (lpr-TU or MpJ-TU group) in the water bottle.

Results

UsC or UsT ameliorates SLE in the MRL-lpr/lpr mice by significantly reducing lymphoproliferation, proteinuria, lesions (tail) and autoantibodies. lpr-CU group had a 20% survival advantage over lpr-water group. However, lpr-TU group lived an average of 16 days shorter than lpr-water group due to complications unrelated to lupus-like illness. CU/TU treatment inhibited lymphadenopathy significantly compared with lpr-water group (p=0.03 and p=0.02, respectively) by induction of apoptosis. Average lymph node weights were 2606±1147, 742±331 and 385±68 mg, respectively, for lpr-water, lpr-CU and lpr-TU mice. Transferase dUTP nick end labelling assay showed that lymphocytes in lymph nodes of lpr-CU and lpr-TU mice underwent apoptosis. Significantly reduced cellular infiltration of the salivary glands in the lpr-TU group compared with the lpr-water group, and a trend towards reduced kidney damage was observed in the lpr-CU and lpr-TU groups.

Conclusions

These studies show that UsC/UsT could prove useful as a therapeutic intervention in SLE/SS.

Exonuclease TREX1 degrades double-stranded DNA to prevent spontaneous lupus-like inflammatory disease

The TREX1 gene encodes a potent DNA exonuclease, and mutations in TREX1 cause a spectrum of lupus-like autoimmune diseases. Most lupus patients develop autoantibodies to double-stranded DNA (dsDNA), but the source of DNA antigen is unknown. The TREX1 D18N mutation causes a monogenic, cutaneous form of lupus called familial chilblain lupus, and the TREX1 D18N enzyme exhibits dysfunctional dsDNA-degrading activity, providing a link between dsDNA degradation and nucleic acid-mediated autoimmune disease. We determined the structure of the TREX1 D18N protein in complex with dsDNA, revealing how this exonuclease uses a novel DNA-unwinding mechanism to separate the polynucleotide strands for single-stranded DNA (ssDNA) loading into the active site. The TREX1 D18N dsDNA interactions coupled with catalytic deficiency explain how this mutant nuclease prevents dsDNA degradation. We tested the effects of TREX1 D18N in vivo by replacing the TREX1 WT gene in mice with the TREX1 D18N allele. The TREX1 D18N mice exhibit systemic inflammation, lymphoid hyperplasia, vasculitis, and kidney disease. The observed lupus-like inflammatory disease is associated with immune activation, production of autoantibodies to dsDNA, and deposition of immune complexes in the kidney. Thus, dysfunctional dsDNA degradation by TREX1 D18N induces disease in mice that recapitulates many characteristics of human lupus. Failure to clear DNA has long been linked to lupus in humans, and these data point to dsDNA as a key substrate for TREX1 and a major antigen source in mice with dysfunctional TREX1 enzyme.

Paradoxical effects of all-trans-retinoic acid on lupus-like disease in the MRL/lpr mouse model

Roles of all-trans-retinoic acid (tRA), a metabolite of vitamin A (VA), in both tolerogenic and immunogenic responses are documented. However, how tRA affects the development of systemic autoimmunity is poorly understood. Here we demonstrate that tRA have paradoxical effects on the development of autoimmune lupus in the MRL/lpr mouse model. We administered, orally, tRA or VA mixed with 10% of tRA (referred to as VARA) to female mice starting from 6 weeks of age. At this age, the mice do not exhibit overt clinical signs of lupus. However, the immunogenic environment preceding disease onset has been established as evidenced by an increase of total IgM/IgG in the plasma and expansion of lymphocytes and dendritic cells in secondary lymphoid organs. After 8 weeks of tRA, but not VARA treatment, significantly higher pathological scores in the skin, brain and lung were observed. These were accompanied by a marked increase in B-cell responses that included autoantibody production and enhanced expression of plasma cell-promoting cytokines. Paradoxically, the number of lymphocytes in the mesenteric lymph node decreased with tRA that led to significantly reduced lymphadenopathy. In addition, tRA differentially affected renal pathology, increasing leukocyte infiltration of renal tubulointerstitium while restoring the size of glomeruli in the kidney cortex. In contrast, minimal induction of inflammation with tRA in the absence of an immunogenic environment in the control mice was observed. Altogether, our results suggest that under a predisposed immunogenic environment in autoimmune lupus, tRA may decrease inflammation in some organs while generating more severe disease in others.

Regulatory T cells in systemic lupus erythematosus

Systemic lupus erythematosus (SLE), an autoimmune disease, develops when immunologic self-tolerance fails. Treg cells are a subset of CD4(+) T cells that maintain self-tolerance by suppressing autoreactive lymphocytes. Defects in Treg cells are therefore considered to be an aspect of SLE pathogenesis. Nevertheless, reports on the numbers and function of Treg cells in SLE are contradictory and the definitive role of Treg cells in SLE remains unclear. In this review, we summarize findings from murine models and ex vivo experiments, which provide insights into the mechanisms that result in the breakdown of tolerance. We also include recent findings about Treg-cell subsets and their markers in human SLE. The identification of unique markers to identify bona fide Treg cells, as well as therapies to reconstitute the balance between Treg cells and autoreactive T cells in SLE, are the future challenges for SLE research.

Humanized TLR7/8 expression drives proliferative multisystemic histiocytosis in C57BL/6 mice

A humanized TLR7/TLR8 transgenic mouse line was engineered for studies using TLR7/8 ligands as vaccine adjuvants. The mice developed a spontaneous immune-mediated phenotype prior to six months of age characterized by runting, lethargy, blepharitis, and corneal ulceration. Histological examination revealed a marked, multisystemic histiocytic infiltrate that effaced normal architecture. The histological changes were distinct from those previously reported in mouse models of systemic lupus erythematosus. When the mice were crossed with MyD88-/- mice, which prevented toll-like receptor signaling, the inflammatory phenotype resolved. Illness may be caused by constitutive activation of human TLR7 or TLR8 in the bacterial artificial chromosome positive mice as increased TLR7 and TLR8 expression or activation has previously been implicated in autoimmune disease.

Effects of pristane alone or combined with chloroquine on macrophage activation, oxidative stress, and TH1/TH2 skewness

We investigated the protective role of chloroquine against pristane-induced macrophage activation, oxidative stress, and Th1/Th2 skewness in C57BL/6J mice. Those mice were treated with pristane alone or combined with chloroquine. Hematological and biochemical parameters, macrophage phagocytic function, the oxidant/antioxidant index, cytokine for IFN-γ, TNF-α, IL-4, and IL-6, and the isotypes of IgG2a and IgG1 were determined. And the expression of T-bet/GATA-3 and IL-12/IL-10 mRNA in spleen were analyzed by real-time PCR. We found that pristane treatment for a period of 12 or 24 weeks triggered macrophage activation syndrome, characterized by hemophagocytosis in spleen and peripheral blood, enhanced lipid phagocytosis by peritoneal macrophages in vitro, erythropenia and leucopenia, increased anti-Smith, lactic dehydrogenase, triglyceride, and ferritin, as well as hypercytokinemia of IFN-γ, TNF-α, IL-4, and IL-6. In parallel, a significant increase in lipid peroxidation and a decrease in superoxide dismutase, glutathione, and catalase activity, as well as a skewed Th1/Th2 balance in spleen, were observed. However, chloroquine supplementation showed a remarkable amelioration of these abnormalities. Our data indicate that pristane administration induces macrophage activation, oxidative stress, and Th1/Th2 skewness, which can be attenuated by chloroquine.

The sympathetic nervous system modulates CD4(+)Foxp3(+) regulatory T cells via noradrenaline-dependent apoptosis in a murine model of lymphoproliferative disease

The sympathetic nervous system (SNS) plays a crucial role in the course and development of autoimmune disease in Fas-deficient lpr/lpr mice. As regulatory T cells (Tregs) are considered important modulators of autoimmune processes, we analyzed the interaction between the SNS and Tregs in this murine model of lymphoproliferative disease. We found that the percentage of Tregs among CD4(+) T cells is increased in the spleen, lymph nodes, and thymus of lpr/lpr mice as compared to age-matched C57Bl/6J (B6) mice. Furthermore, noradrenaline (NA), the main sympathetic neurotransmitter, induced apoptosis in B6- and lpr/lpr-derived Tregs. NA also reduced the frequency of Foxp3(+) cells and Foxp3 mRNA expression via β2-adrenoceptor (β2-AR)-mediated mechanisms in a concentration and time-dependent manner. Destruction of peripheral sympathetic nerves by 6-hydroxydopamine significantly increased the percentage of Tregs in B6 control mice to an extent comparable to aged-matched lpr/lpr mice. The concentration of splenic NA negatively correlated with the frequency of CD4(+)Foxp3(+) Tregs. Additionally, 60days after sympathectomy, a partial recovery of NA concentrations led to Treg percentages comparable to those of intact, vehicle-treated controls. Immunohistochemical analysis of the spleen revealed localization of single Foxp3(+) Tregs in proximity to NA-producing nerve fibers, providing an interface between Tregs and the SNS. Taken together, our data suggest a relation between the degree of splenic sympathetic innervation and the size of the Treg compartment. While there are few examples of endogenous substances capable of affecting Tregs, our results provide a possible explanation of how the magnitude of the Treg compartment in the spleen can be regulated by the SNS.

MicroRNA-let-7a expression is increased in the mesangial cells of NZB/W mice and increases IL-6 production in vitro

Recent evidence supports a role for epigenetic alterations in the pathogenesis of systemic lupus erythematosus (SLE). MicroRNAs (miRNAs or miRs) are endogenous epigenetic regulators whose expression is altered in many diseases, including SLE. IL-6 is an inflammatory cytokine produced by mesangial cells during lupus nephritis (LN). IL-6 contains a potential binding site for miRNA-let-7a (let-7a) in its 3' untranslated region (UTR). We found let-7a expression was significantly increased in the mesangial cells of pre-diseased and actively diseased New Zealand Black/White (NZB/W) mice compared to age-matched New Zealand White (NZW) mice. Overexpression of let-7a in vitro increased IL-6 production in stimulated mesangial cells compared to non-transfected controls. Inhibition of let-7a did not significantly affect immune-stimulated IL-6 production. When stimulated mesangial cells overexpressing let-7a were treated with the transcription inhibitor Actinomycin D (ActD), IL-6 was degraded faster, consistent with the direct targeting of the 3' UTR of IL-6 by let-7a. Overexpression of let-7a increased the expression of tristetraprolin (TTP), an RNA-binding protein (RBP) that has 5 potential binding regions in the 3' UTR of IL-6. ActD inhibited the transcription of proteins including TTP that may contribute to the let-7a-mediated increase in immune-stimulated IL-6 production. These data show that NZB/W mice have higher let-7a expression than NZW mice and that increased let-7a expression in vitro increases IL-6 production in stimulated mesangial cells. Further studies examining the role of let-7a expression in inflammation are warranted.

Generation of self-peptides to treat systemic lupus erythematosus

Synthetic peptides are attracting increasing attention as therapeutics. Despite their potential, however, only a few selected peptides have been able to enter in clinical trials for chronic autoimmune diseases and systemic lupus erythematosus (SLE) in particular. Here, we describe and discuss a series of assays, which may help in characterizing valuable candidate peptides that were applied in our laboratory to develop the lupus P140 peptide program. The different steps of selection include the choice of the initial autoantigen, the design, synthesis and purification of peptides, their preliminary screen by measuring cytokines produced ex vivo by T cells and their binding to major histocompatibility complex class II (MHCII) molecules, their capacity to lower peripheral cell hyperproliferation in lupus-prone MRL/lpr mice, and, as a final step, their ability to slow down the development of lupus disease in model animals.

Experimental use of mouse models of systemic lupus erythematosus

Mouse models of lupus have for many years provided accessible and reliable research systems for the pathogenesis and therapy of systemic autoimmune disease, spanning a spectrum of inbred strains that develop spontaneous disease to experimentally induced, sometimes genetically manipulated animals. Nearly all the models share in common the development of glomerulonephritis and autoantibodies, including antinuclear and DNA specificities, the most common endpoints examined in experimental studies, but exhibit specific differences in the incidence of other end-organ manifestations such as hemolytic anemia, arthritis, dermatitis, and vasculitis. This chapter contrasts the clinical characteristics of these various models, providing an outline for their use and analysis.