Murine models of systemic lupus erythematosus

Sex-specific differences in SLE - Significance in the experimental setting of inflammation and kidney damage in MRL-Faslpr mice

Animal models are an important tool in the research of chronic autoimmune diseases, like systemic lupus erythematosus (SLE). MRL-Faslpr mice are one of different lupus models that develop spontaneously an SLE-like disease with autoantibodies and immune complex deposition that leads into damage of different organs. In contrast to human SLE, both sexes of MRL-Faslpr mice develop a similar autoimmune disease. Due to the sex bias in human and the delayed disease progression in male MRL-Faslpr mice, the majority of studies have been performed in female mice. To determine the suitability of male MRL-Faslpr mice for SLE research, especially with regard to the 3 R-principle and animal welfare, analyses of phenotype, inflammation and damage with focus on kidney and spleen were performed in mice of both sexes. Female mice developed lymphadenopathy and skin lesions earlier as males. At an age of 3.5 month, more immune cells infiltrated kidney and spleen in females compared to males. At the age of 5 months, however, substantially less sex-specific differences were detected. Since other studies have shown differences between both sexes on other manifestations like autoimmune pancreatitis and Sjögren syndrome in MRL-Faslpr mice, the use of male mice as part of 3 R-principle and animal welfare must be carefully considered.

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.

Upregulation of PD-1 and its ligands and expansion of T peripheral helper cells in the nephritic kidneys of lupus-prone BXSB-Yaa mice

OBJECTIVE

This study aimed to investigate the role of the programmed cell death protein 1 (PD-1) pathway and T peripheral helper (Tph) cells in the pathogenesis of lupus nephritis using lupus-prone BXSB-Yaa mice.

METHODS

Male BXSB-Yaa mice and age-matched male C57BL/6 mice were used. The expression of PD-1 and its ligands (programmed cell death 1 ligand-1, PD-L1 and programmed cell death 1 ligand-2, PD-L2) and the phenotypes of kidney-derived cells and splenocytes expressing these molecules were analyzed by immunofluorescence and flow cytometry.

RESULTS

Nephritis spontaneously developed in 16-week-old but not in 8-week-old BXSB-Yaa or C57BL/6 mice. PD-1 was expressed on CD4+ mononuclear cells (MNCs) that infiltrated the glomeruli of 16-week-old BXSB-Yaa mice. The frequency of CD4+PD-1+CXCR5-ICOS+ kidney-derived Tph cells was higher in 16-week-old than in 8-week-old BXSB-Yaa and C57BL/6 mice, whereas the frequency of CD4+PD-1+CXCR5+ICOS+ kidney-derived T follicular helper (Tfh) cells was not significantly different between the mice. PD-L1 was constitutively expressed in the renal tubules. PD-L2 was expressed in the glomeruli of 16-week-old BXSB-Yaa mice. The frequency of PD-L1highCD11c+CD3-CD19- and PD-L2+CD11c+CD3-CD19- kidney-derived MNCs in 16-week-old BXSB-Yaa mice was significantly higher than that of the control mice. The percentage of kidney-derived Tph cells but not Tfh cells was correlated with the urinary protein levels in the nephritic mice.

CONCLUSION

The results of this study suggest that kidney-infiltrating PD-1+ Tph cells expanded concomitantly with the upregulation of PD-L1 and PD-L2 in the kidneys and the progression of lupus nephritis.

Inhibition of receptor interacting protein kinase-1 (RIPK1) in the treatment of murine lupus

OBJECTIVE

Systemic lupus erythematosus (SLE) is a type of autoimmune disease that involves multiple organs involved as well as cytokine dysregulation. The treatment of SLE is still challenging due to the side effects of the different drugs used. Receptor-interacting protein kinase 1 (RIPK1) is a kinase involved in T cell homeostasis and autoinflammation. Although clinical trials have shown that RIPK1 inhibition exhibits significant efficacy in different autoimmune diseases, its role in SLE remains unclear.

METHODS

MRL/lpr lupus-prone mice received RIPK1 inhibitor ZJU37 or vehicle intraperitoneally for 10 weeks. A BM12-induced chronic graft-versus-host-disease (cGVHD) lupus-like model was introduced in RIPK1 D138N mice or C57BL/6 mice. Nephritis, serum autoantibody levels, dysregulation of adaptive immune response and cytokines were compared in treated and untreated mice.

RESULTS

ZJU37 alleviated the clinical features of the MRL/lpr mice including nephritis and anti-dsDNA antibody production. In addition, ZJU37 treatment reduced the proportion of double-negative T cells in the spleen and the cytokines of TNFα, IFN-γ, IL-6, IL-17 and IL-1β in the serum. Moreover, RIPK1 D138N mice were able to prevent the cGVHD lupus-like model from SLE attack, manifesting as anti-dsDNA antibody production, the proliferation of germinal centre B cells, plasma cells, and T follicular helper cells as well as IgG and C3 deposits in kidneys.

CONCLUSION

RIPK1 inhibition has a protective effect in the mouse model of SLE and can potentially become a new therapeutic target for SLE in humans.

A Novel Murine Model for Lupus-Like Ocular Chronic Graft-Versus-Host Disease

Purpose

Lupus-like chronic graft-versus-host disease (cGVHD) has been previously described, but the ocular findings have not been elucidated. Recipient mice in a lupus-like cGVHD model manifested notable and persistent ocular surface phenotypes. Herein, we further explored immunopathogenic mechanisms underlying these ocular phenotypes.

Methods

A previously described lupus-like cGVHD model was established by intraperitoneal injection of splenocytes from bm12 mice into C57BL/6J mice. Systemic findings were evaluated for the presence of splenomegaly, proteinuria, and autoantibodies. Comprehensive evaluations were conducted on ocular manifestations and immunopathological features in this model.

Results

The lupus-like cGVHD model was successfully constructed 2 weeks post-transplantation. The recipient mice developed lupus-like phenotypes, including splenomegaly, proteinuria, and increased autoantibodies, and their ocular presentations included corneal epithelial defects and decreased tear secretion. Histological analysis revealed a reduction in corneal nerve fiber density and corneal endothelial cells, along with conjunctival fibrosis and loss of goblet cells. Moreover, cGVHD induced progressive aggravation of immune cell infiltration and fibrosis in the lacrimal glands. RNA-Sequencing (RNA-seq) results of the lacrimal glands demonstrated that the differentially expressed genes (DEGs) between the control and cGVHD groups were associated with GVHD pathways. Immune infiltration analysis using RNA-seq and flow cytometry confirmed that CD8+ T lymphocytes predominantly constituted the inflammatory infiltrating cells within the lacrimal glands.

Conclusions

This lupus-like cGVHD model (bm12→C57BL/6J) exhibited persistent ocular surface manifestations, characterized by immune infiltration of CD8+ T lymphocytes in the lacrimal glands. Thus, this ocular cGVHD model may be used to explore the underlying mechanisms and discover novel therapeutic interventions.

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.

Constitutive knockout of interleukin-6 ameliorates memory deficits and entorhinal astrocytosis in the MRL/lpr mouse model of neuropsychiatric lupus

BACKGROUND

Neuropsychiatric lupus (NPSLE) describes the cognitive, memory, and affective emotional burdens faced by many lupus patients. While NPSLE's pathogenesis has not been fully elucidated, clinical imaging studies and cerebrospinal fluid (CSF) findings, namely elevated interleukin-6 (IL-6) levels, point to ongoing neuroinflammation in affected patients. Not only linked to systemic autoimmunity, IL-6 can also activate neurotoxic glial cells the brain. A prior pre-clinical study demonstrated that IL-6 can acutely induce a loss of sucrose preference; the present study sought to assess the necessity of chronic IL-6 exposure in the NPSLE-like disease of MRL/lpr lupus mice.

METHODS

We quantified 1308 proteins in individual serum or pooled CSF samples from MRL/lpr and control MRL/mpj mice using protein microarrays. Serum IL-6 levels were plotted against characteristic NPSLE neurobehavioral deficits. Next, IL-6 knockout MRL/lpr (IL-6 KO; n = 15) and IL-6 wildtype MRL/lpr mice (IL-6 WT; n = 15) underwent behavioral testing, focusing on murine correlates of learning and memory deficits, depression, and anxiety. Using qPCR, we quantified the expression of inflammatory genes in the cortex and hippocampus of MRL/lpr IL-6 KO and WT mice. Immunofluorescent staining was performed to quantify numbers of microglia (Iba1 +) and astrocytes (GFAP +) in multiple cortical regions, the hippocampus, and the amygdala.

RESULTS

MRL/lpr CSF analyses revealed increases in IL-17, MCP-1, TNF-α, and IL-6 (a priori p-value < 0.1). Serum levels of IL-6 correlated with learning and memory performance (R2 = 0.58; p = 0.03), but not motivated behavior, in MRL/lpr mice. Compared to MRL/lpr IL-6 WT, IL-6 KO mice exhibited improved novelty preference on object placement (45.4% vs 60.2%, p < 0.0001) and object recognition (48.9% vs 67.9%, p = 0.002) but equivalent performance in tests for anxiety-like disease and depression-like behavior. IL-6 KO mice displayed decreased cortical expression of aif1 (microglia; p = 0.049) and gfap (astrocytes; p = 0.044). Correspondingly, IL-6 KO mice exhibited decreased density of GFAP + cells compared to IL-6 WT in the entorhinal cortex (89 vs 148 cells/mm2, p = 0.037), an area vital to memory.

CONCLUSIONS

The inflammatory composition of MRL/lpr CSF resembles that of human NPSLE patients. Increased in the CNS, IL-6 is necessary to the development of learning and memory deficits in the MRL/lpr model of NPSLE. Furthermore, the stimulation of entorhinal astrocytosis appears to be a key mechanism by which IL-6 promotes these behavioral deficits.

Double-Negative T (DNT) Cells in Patients with Systemic Lupus Erythematosus

Double-negative T (DNT) cells are a rare and unconventional T-lymphocyte subpopulation lacking both CD4 and CD8 markers. Their immunopathological roles and clinical relevance have yet to be elucidated. Beyond autoimmune lymphoproliferative syndrome (ALPS), these cells may also play a role in rheumatic disorders, including systemic lupus erythematosus (SLE); indeed, these two diseases share several autoimmune manifestations (including nephritis). Moreover, one of the main experimental murine models used to investigate lupus, namely the MRL/lpr mouse, is characterized by an expansion of DNT cells, which can support the production of pathogenic autoantibodies and/or modulate the immune response in this context. However, lupus murine models are not completely consistent with their human SLE counterpart, of course. In this mini review, we summarize and analyze the most relevant clinical studies investigating the DNT cell population in SLE patients. Overall, based on the present literature review and analysis, DNT cell homeostasis seems to be altered in patients with SLE. Indeed, most of the available clinical studies (which include both adults and children) reported an increased DNT cell percentage in SLE patients, especially during the active phases, even though no clear correlation with disease activity and/or inflammatory parameters has been clearly established. Well-designed, standardized, and longitudinal clinical studies focused on DNT cell population are needed, in order to further elucidate the actual contribution of these cells in SLE pathogenesis and their interactions with other immune cells (also implicated and/or altered in SLE, such as basophils), and clarify whether their expansion and/or immunophenotypic aspects may have any immunopathological relevance (and, then, represent potential disease markers and, in perspective, even therapeutic targets) or are just an unspecific epiphenomenon of autoimmunity.

The super-healing MRL strain promotes muscle growth in muscular dystrophy through a regenerative extracellular matrix

The Murphy Roths Large (MRL) mouse strain has "super-healing" properties that enhance recovery from injury. In mice, the DBA/2J strain intensifies many aspects of muscular dystrophy, so we evaluated the ability of the MRL strain to suppress muscular dystrophy in the Sgcg-null mouse model of limb girdle muscular dystrophy. A comparative analysis of Sgcg-null mice in the DBA/2J versus MRL strains showed greater myofiber regeneration, with reduced structural degradation of muscle in the MRL strain. Transcriptomic profiling of dystrophic muscle indicated strain-dependent expression of extracellular matrix (ECM) and TGF-β signaling genes. To investigate the MRL ECM, cellular components were removed from dystrophic muscle sections to generate decellularized myoscaffolds. Decellularized myoscaffolds from dystrophic mice in the protective MRL strain had significantly less deposition of collagen and matrix-bound TGF-β1 and TGF-β3 throughout the matrix. Dystrophic myoscaffolds from the MRL background, but not the DBA/2J background, were enriched in myokines like IGF-1 and IL-6. C2C12 myoblasts seeded onto decellularized matrices from Sgcg-/- MRL and Sgcg-/- DBA/2J muscles showed the MRL background induced greater myoblast differentiation compared with dystrophic DBA/2J myoscaffolds. Thus, the MRL background imparts its effect through a highly regenerative ECM, which is active even in muscular dystrophy.

Novel biomarker discovery through comprehensive proteomic analysis of lupus mouse serum

OBJECTIVES

The difficulty of monitoring organ-specific pathology in systemic lupus erythematosus (SLE) often complicates disease prognostication and treatment. Improved non-invasive biomarkers of active organ pathology, particularly lupus nephritis, would improve patient care. We sought to validate and apply a novel strategy to generate the first comprehensive serum proteome of a lupus mouse model and identify mechanism-linked lupus biomarker candidates for subsequent clinical investigation.

METHODS

Serum levels of 1308 diverse proteins were measured in eight adult female MRL/lpr lupus mice and eight control MRL/mpj mice. ELISA validation confirmed fold increases. Protein enrichment analysis provided biological relevance to findings. Individual protein levels were correlated with measures of lymphoproliferative, humoral, and renal disease.

RESULTS

Four hundred and six proteins were increased in MRL/lpr serum, including proteins increased in human SLE such as VCAM-1, L-selectin, TNFRI/II, TWEAK, CXCL13, MCP-1, IP-10, IL-10, and TARC. Newly validated proteins included IL-6, IL-17, and MDC. Results of pathway enrichment analysis, which revealed enhancement of cytokine signaling and immune cell migration, reinforced the similarity of the MRL/lpr disease to human pathology. Fifty-two proteins positively correlated with at least one measure of lupus-like disease. TECK, TSLP, PDGFR-alpha, and MDC were identified as novel candidate biomarkers of renal disease.

CONCLUSIONS

We successfully validated a novel serum proteomic screening strategy in a spontaneous murine lupus model that highlighted potential new biomarkers. Importantly, we generated a comprehensive snapshot of the serum proteome which will enable identification of other candidates and serve as a reference for future mechanistic and therapeutic studies in lupus.

Analysis of Nanoparticles' Potential to Induce Autoimmunity

Autoimmune responses are characterized by the presence of antibodies and lymphocytes specific to self or so-called autoantigens. Among such autoantigens is DNA; therefore, screening for antibodies recognizing single- and/or double-stranded DNA is commonly used to detect and classify autoimmune diseases. While autoimmunity affects both sexes, females are generally more affected than males, which is recapitulated in some animal models. A variety of factors, including genetic predisposition and the environment, contribute to the development of autoimmune disorders. Since certain drug products may also contribute to the development of autoimmunity, understanding a drug's potential to trigger an autoimmune response is of interest to immunotoxicology. However, models to study autoimmunity are limited, and it is generally agreed that no model can accurately predict autoimmunity in humans. Herein, we present an in vivo protocol utilizing the SJL/J mouse model to study nanoparticles' effects on the development of autoimmune responses. The protocol is adapted from the literature describing the use of this model to study chemically induced lupus.

Jieduquyuziyin prescription enhances CD11a and CD70 DNA methylation of CD4+ T cells via miR-29b-sp1/DNMT1 pathway in MRL/lpr mice

ETHNOPHARMACOLOGICAL RELEVANCE

Jieduquyuziyin prescription (JP) is a traditional Chinese medicine utilized to treat systemic lupus erythematosus (SLE). Its efficacy has been confirmed through clinical trials and empirical evidence, leading to its authorized use in Chinese hospitals. The development of JP exemplifies the integration of traditional wisdom and scientific approaches, demonstrating the interdisciplinary essence of ethnopharmacology. These results emphasize the potential value of traditional medicine in addressing autoimmune disorders.

AIM OF THE STUDY

This study aims to address the effect of JP in MRL/lpr mice and elucidate the pharmacological mechanism by which JP targets CD11a and CD70 DNA methylation via the miR-29b-sp1/DNMT1 pathway.

MATERIALS AND METHODS

MRL/lpr mice were divided into three groups: the model group (received distilled water), the positive group (administered AAV/miR-29b-3p inhibitor), and the JP group (treated with JP decoction). C57BL/6 mice were constituted as a control group. Through ELISA assay, serum and urine samples were assessed for anti-dsDNA, TNF-α, TGF-β, IL-2, and UP. HE and Masson staining were conducted to reveal renal pathology. Genome DNA was extracted from CD4+ T cells of mice spleens to evaluate methylation level. The methylation of CD11a, CD70, and CD40L promoter regions was analyzed by targeted bisulfate sequencing. Their expression at the mRNA and protein levels was examined using quantitative real-time PCR, western blot analysis, immunohistochemistry, and immunofluorescence staining of kidney tissues. Furthermore, the molecular mechanisms underlying the regulation of the miR-29b-sp1/DNMT1 pathway by JP were explored with Jurkat cells transfected with miR-inhibitors or miR-mimics.

RESULTS

Mice treated with JP exhibited a significant decrease in anti-dsDNA, TNF-α, TGF-β, and UP, accompanied by a significant increase in IL-2. HE staining revealed JP effectively mitigated renal inflammatory response, while Masson staining indicated a reduction in collagen fiber content. In addition, JP exhibited a significant impact on the global hypomethylation of SLE, as evidenced by the induction of high methylation levels of CD11a and CD70 promoter regions, mediated through the miR-29b-sp1/DNMT1 pathway.

CONCLUSION

Our findings demonstrate JP exerts a protective effect against spontaneous SLE development, attenuates renal pathological changes, and functions as a miRNA inhibitor to enhance CD11a and CD70 DNA methylation through the modulation of the miR-29b-sp1/DNMT1 pathway.

Mesenchymal stem cell secretome ameliorates over-expression of soluble fms-like tyrosine kinase-1 (sFlt-1) and fetal growth restriction (FGR) in animal SLE model

INTRODUCTION

In the near future, stem cell research may lead to several major therapeutic innovations in medical practice. Secretome, a "by-product" of stem cell line cultures, has many advantages. Its easiness of storage, usage, and fast direct effect are some of those to consider. Fetal growth restriction (FGR) remains one of the significant challenges in maternal-fetal and neonatal medicine. Placentation failure is one of the most profound causal and is often related to increasing sFlt-1 in early pregnancy. This study aimed to investigate hUC-MSC secretome in ameliorating sFlt-1 and how to improve outcomes in preventing FGR in an animal model.

MATERIALS AND METHODS

Pristane-induced systemic lupus erythematosus (SLE) in a mouse model was used to represent placentation failure and its consequences. Twenty-one mice were randomized into three groups: (I) normal pregnancy, (II) SLE, and (III) SLE with secretome treatment. Pristane was administered in all Groups four weeks prior mating period. Secretome was derived from human umbilical cord mesenchymal stem cells (hUC-MSC) conditioned medium on the 3rd and 4th passage, around day-21 until day-28 from the start of culturing process. Mesenchymal stem cell was characterized using flow cytometry for CD105+, CD90+, and CD73+ surface antigen markers. Immunohistochemistry anlysis by using Remmele's Immunoreactive Score (IRS) was used to quantify the placental sFlt-1 expression in each group. Birth weight and length were analyzed as the secondary outcome. The number of fetuses obtained was also calculated for pregnancy loss comparison between Groups.

RESULTS

The administration of secretome of hUC-MSC was found to lower the expression of the placental sFlt-1 significantly in the pristane SLE animal model (10.30 ± 1.40 vs. 4.98 ± 2.57; p < 0.001) to a level seen in normal mouse pregnancies in Group I (3.88 ± 0.49; p = 0.159). Secretome also had a significant effect on preventing fetal growth restriction in the pristane SLE mouse model (birth weight: 354.29 ± 80.76 mg vs. 550 ± 64.03 mg; p < 0.001 and birth length: 14.43 ± 1.27 mm vs. 19.00 ± 1.41 mm), comparable to the birth weight and length of the normal pregnancy in Group I (540.29 ± 75.47 mg and 18.14 ± 1.34 mm, p = 0.808 and = 0.719). Secretome administration also showed a potential action to prevent high number of pregnancy loss as the number of fetuses obtained could be similar to those of mice in the normal pregnant Group (7.71 ± 1.11 vs. 7.86 ± 1.06; p = 0.794).

CONCLUSIONS

Administration of secretome lowers sFlt-1 expression in placenta, improves fetal growth, and prevents pregnancy loss in a mouse SLE model.

Systemic lupus erythematosus in American Indian/Alaska natives: Incorporating our new understanding of the biology of trauma

OBJECTIVE

To review the literature regarding systemic lupus erythematosus (SLE) in American Indian/Alaska Native (AI/AN) people and relate prevalence and/or disease severity to our emerging understanding of the biology of trauma and toxic stress.

METHODS

We conducted a search and review of the literature using search terms "lupus and American Indians" "ACEs and disease outcome" "Biology of Adversity" "lupus and ACE scores," " lupus and childhood abuse." These search criteria were entered into Google Scholar and articles retrieved from PubMed, NBCI. This approach yielded a small numbers of papers used throughout this review. We excluded articles that were not published in a peer reviewed journals, as well as editorial commentaries.

RESULTS

In the AI/AN population, SLE shows high prevalence rates and severe disease manifestations, comparable to the African American population. AI/AN populations also have high rates of childhood trauma. Toxic stress and trauma such as those catalogued in the Adverse Childhood Experiences (ACE) study have broad-reaching immunologic and epigenetic effects that are likely to be relevant to our understanding of SLE in AI/AN people.

CONCLUSIONS

AI/AN people have high rates of SLE. These high rates are likely to be driven by many complex factors, not all of which are genetic. Future research is needed to establish (or refute) a causal connection between the biology of adversity and SLE in socially marginalized and historically traumatized populations.

Targeted stimulation of the vagus nerve reduces renal injury in female mice with systemic lupus erythematosus

Pharmacological stimulation of the vagus nerve has been shown to suppress inflammation and reduce blood pressure in a murine model of systemic lupus erythematosus (SLE) that is characterized by hypertension, inflammation, renal injury and dysautonomia. The present study aims to directly stimulate vagal nerves at the level of the dorsal motor nucleus of the vagus (DMV) using designer receptors exclusively activated by designer drugs (DREADDs) to determine if there is similar protection and confirm mechanism. Female NZBWF1/J (SLE) mice and NZW/LacJ mice (controls, labeled as NZW throughout) received bilateral microinjections of pAAV-hSyn-hM3D(Gq)-mCherry or control virus into the DMV at 31 weeks of age. After two weeks of recovery and viral transfection, the DREADD agonist clozapine-N-oxide (CNO; 3 mg/kg) was injected subcutaneously for an additional 14 days. At 35 weeks, mean arterial pressure (MAP; mmHg) was increased in SLE mice compared to NZW mice, but selective activation of DMV neurons did not significantly alter MAP in either group. SLE mice had higher indices of renal injury including albumin excretion rate (μg/day), glomerulosclerosis index, interstitial fibrosis, neutrophil gelatinase-associated lipocalin (NGAL), and kidney injury molecule-1 (KIM-1) compared to NZW mice. Selective DMV neuronal activation reduced albumin excretion rate, glomerulosclerosis, interstitial fibrosis, and NGAL in SLE mice but not NZW mice. Together, these data indicate that selective activation of neurons within the DMV by DREADD protects the kidney suggesting an important role of vagus-mediated pathways in the progression of renal injury in SLE.

Evaluation of causal associations between interleukin-18 levels and immune-mediated inflammatory diseases: a Mendelian randomization study

BACKGROUND

Altered interleukin (IL)-18 levels are associated with immune-mediated inflammatory diseases (IMIDs), but no studies have investigated their causal relationship. This study aimed to examine the causal associations between IL-18 and IMIDs.

METHODS

We performed a two-sample Mendelian randomization (MR) analysis. Genetic variants were selected from genome-wide association study datasets following stringent assessments. We then used these variants as instrumental variables to estimate the causal effects of IL-18 levels on the risk of developing five common IMIDs: rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), inflammatory bowel disease (IBD), ankylosing spondylitis (AS), and psoriasis. We used the inverse variance-weighted (IVW) method as the primary analysis, with sensitivity analyses performed to avoid potential bias. Reverse-direction MR analyses were performed to rule out the possibility of reverse associations.

RESULTS

We found that genetically determined higher circulating IL-18 levels were causally associated with a higher risk for SLE (PIVW = 0.009; OR, 1.214; 95% CI, 1.049 - 1.404) and IBD (PIVW < 0.001; OR, 1.142; 95% CI, 1.062 - 1.228), but found no significant associations of IL-18 with RA (PIVW = 0.496; OR, 1.044; 95% CI, 0.923 - 1.180), AS (PIVW = 0.021; OR, 1.181; 95% CI, 1.025 - 1.361), or psoriasis (PIVW = 0.232; OR, 1.198; 95% CI, 0.891 - 1.611). In the reverse direction, no causal relationship existed between SLE or IBD and IL-18 levels. Globally, sensitivity studies using alternative MR methods supported the results that were robust and reliable. The Cochran's Q test, MR-Egger intercept, and MR-Pleiotropy RESidual Sum and Outlier excluded the influence of heterogeneity, horizontal pleiotropy, and outliers.

CONCLUSIONS

We have demonstrated that elevated IL-18 levels increase the risk of SLE and IBD but not RA, AS, or psoriasis. The results enhanced our understanding of IL-18 in the pathology of IMIDs.

TRIM55 promotes noncanonical NF-κB signaling and B cell-mediated immune responses by coordinating p100 ubiquitination and processing

The ubiquitination-dependent processing of NF-κB2 (also known as p100) is a critical step in the activation of the noncanonical NF-κB pathway. We investigated the molecular mechanisms regulating this process and showed that TRIM55 was the E3 ubiquitin ligase that mediated the ubiquitination of p100 and coordinated its processing. TRIM55 deficiency impaired noncanonical NF-κB activation and B cell function. Mice with a B cell-specific Trim55 deficiency exhibited reduced germinal center formation and antibody production. These mice showed less severe symptoms than those of control mice upon the induction of a systemic lupus-like disease, suggesting B cell-intrinsic functions of TRIM55 in humoral immune responses and autoimmunity. Mechanistically, the ubiquitination of p100 mediated by TRIM55 was crucial for p100 processing by VCP, an ATPase that mediates ubiquitin-dependent protein degradation by the proteasome. Furthermore, we found that TRIM55 facilitated the interaction between TRIM21 and VCP as well as TRIM21-mediated K63-ubiquitination of VCP, both of which were indispensable for the formation of the VCP-UFD1-NPL4 complex and p100 processing. Together, our results reveal a mechanism by which TRIM55 fine-tunes p100 processing and regulates B cell-dependent immune responses in vivo, highlighting TRIM55 as a potential therapeutic target for lupus-like disease.

The P2X7 Receptor in Autoimmunity

The P2X7 receptor (P2X7R) is an ATP-gated nonselective cationic channel that, upon intense stimulation, can progress to the opening of a pore permeable to molecules up to 900 Da. Apart from its broad expression in cells of the innate and adaptive immune systems, it is expressed in multiple cell types in different tissues. The dual gating property of P2X7R is instrumental in determining cellular responses, which depend on the expression level of the receptor, timing of stimulation, and microenvironmental cues, thus often complicating the interpretation of experimental data in comprehensive settings. Here we review the existing literature on P2X7R activity in autoimmunity, pinpointing the different functions in cells involved in the immunopathological processes that can make it difficult to model as a druggable target.

Urine SERPINC1/ORM1 as biomarkers for early detection of lupus nephritis in MRL-lpr mice

Background

To evaluate the usefulness of urine SERPINC1 and ORM1 as biomarkers for early detection of lupus nephritis (LN).

Methods

Using proteomics, we screened for potential urine biomarkers that differentiate LN from systemic lupus erythematosus (SLE) patients without nephritis. In addition, urine levels of target biomarkers were measured by ELISA in 13- and 23-week-old MRL-lpr (murine model for LN) and MRL/MpJ mice. Histological analysis was also performed on the kidneys of 23-week-old mice.

Results

Urine SERPINC1 and ORM1 were elevated in SLE patients with newly diagnosed LN compared with SLE patients without LN (SERPINC1, AUC=.892, P<.001; ORM1, AUC=.886, P<.001). Levels of urine SERPINC1 and ORM1 were also significantly higher in MRL-lpr mice than in MRL/MpJ mice at 13 and 23 weeks (SERPINC1: p<.01 and p<.001 at 13 and 23 weeks, respectively; ORM1: p<.01 at 13 and 23 weeks). In contrast, a significant difference in urine albumin between the two groups was only observed at 23 weeks (p<.001) not at 13 weeks (p=.83). Regarding the kidney pathology of MPL-lpr mice, urine ORM1 and urine albumin, but not urine SERPINC1, were positively correlated with the activity index (ORM1, rho =.879, p<.001; albumin, rho =.807, p=.003) and chronicity index (ORM1, rho =.947, p<.001; albumin, rho =.869, p<.001).

Conclusion

We propose that urine SERPINC1 and ORM1 are novel biomarkers for early LN.

The super-healing MRL strain promotes muscle growth in muscular dystrophy through a regenerative extracellular matrix

Genetic background shifts the severity of muscular dystrophy. In mice, the DBA/2J strain confers a more severe muscular dystrophy phenotype, whereas the Murphy's Roth Large (MRL) strain has "super-healing" properties that reduce fibrosis. A comparative analysis of the Sgcg null model of Limb Girdle Muscular Dystrophy in the DBA/2J versus MRL strain showed the MRL background was associated with greater myofiber regeneration and reduced structural degradation of muscle. Transcriptomic profiling of dystrophic muscle in the DBA/2J and MRL strains indicated strain-dependent expression of the extracellular matrix (ECM) and TGF-β signaling genes. To investigate the MRL ECM, cellular components were removed from dystrophic muscle sections to generate decellularized "myoscaffolds". Decellularized myoscaffolds from dystrophic mice in the protective MRL strain had significantly less deposition of collagen and matrix-bound TGF-β1 and TGF-β3 throughout the matrix, and dystrophic myoscaffolds from the MRL background were enriched in myokines. C2C12 myoblasts were seeded onto decellularized matrices from Sgcg-/- MRL and Sgcg-/- DBA/2J matrices. Acellular myoscaffolds from the dystrophic MRL background induced myoblast differentiation and growth compared to dystrophic myoscaffolds from the DBA/2J matrices. These studies establish that the MRL background also generates its effect through a highly regenerative ECM, which is active even in muscular dystrophy.

Fecal microbiota from MRL/lpr mice exacerbates pristane-induced lupus

BACKGROUND

The roles of gut microbiota in the pathogenesis of SLE have been receiving much attention during recent years. However, it remains unknown how fecal microbiota transplantation (FMT) and microbial metabolites affect immune responses and lupus progression.

METHODS

We transferred fecal microbiota from MRL/lpr (Lpr) mice and MRL/Mpj (Mpj) mice or PBS to pristane-induced lupus mice and observed disease development. We also screened gut microbiota and metabolite spectrums of pristane-induced lupus mice with FMT via 16S rRNA sequencing, metagenomic sequencing, and metabolomics, followed by correlation analysis.

RESULTS

FMT from MRL/lpr mice promoted the pathogenesis of pristane-induced lupus and affected immune cell profiles in the intestine, particularly the plasma cells. The structure and composition of microbial communities in the gut of the FMT-Lpr mice were different from those of the FMT-Mpj mice and FMT-PBS mice. The abundances of specific microbes such as prevotella taxa were predominantly elevated in the gut microbiome of the FMT-Lpr mice, which were positively associated with functional pathways such as cyanoamino acid metabolism. Differential metabolites such as valine and L-isoleucine were identified with varied abundances among the three groups. The abundance alterations of the prevotella taxa may affect the phenotypic changes such as proteinuria levels in the pristane-induced lupus mice.

CONCLUSION

These findings further confirm that gut microbiota play an important role in the pathogenesis of lupus. Thus, altering the gut microbiome may provide a novel way to treat lupus.

Gut microbiota in SLE: from animal models to clinical evidence and pharmacological perspectives

Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease driven by complex interactions between genetics and environmental factors. SLE is characterised by breaking self-immune tolerance and autoantibody production that triggers inflammation and damage of multiple organs. Given the highly heterogeneous nature of SLE, the treatments currently used are still not satisfactory with considerable side effects, and the development of new therapies is a major health issue for better patient management. In this context, mouse models significantly contribute to our knowledge of the pathogenesis of SLE and are an invaluable tool for testing novel therapeutic targets. Here, we discuss the role of the most used SLE mouse models and their contribution to therapeutic improvement. Considering the complexity of developing targeted therapies for SLE, adjuvant therapies are also increasingly proposed. Indeed, murine and human studies have recently revealed that gut microbiota is a potential target and holds great promises for successful new SLE therapies. However, the mechanisms of gut microbiota dysbiosis in SLE remain unclear to date. In this review, we propose an inventory of existing studies investigating the relationship between gut microbiota dysbiosis and SLE to establish microbiome signature that may serve as a potential biomarker of the disease and its severity as well as a new potential therapy target. This approach may open new possibilities for early diagnosis, prevention and therapeutic perspectives of SLE based on gut microbiome.

Maternal antibody repertoire restriction modulates the development of lupus-like disease in BXSB offspring

Systemic lupus erythematosus (SLE) is a complex autoimmune disease that has a strong preference for women of child-bearing age. Maternal factors play an essential role in shaping the immune system of the newborn, yet it is unknown whether maternal factors could modulate the development of SLE in the offspring. Activation-induced cytidine deaminase (AID) is an enzyme required for somatic hypermutation and class switch recombination. Given that IgG and IgA isotypes account for the vast majority of passive immunity in rodents, our previously established AID-deficient BXSB mice provide a model in which maternal antibodies that can be transferred to the offspring are greatly diminished and have restricted repertoire. In this study, we compared genotypically identical mice born to either AID-sufficient dams or AID-deficient dams and evaluated the effects of maternal antibodies in disease progression. Offspring from knockout dams developed disease at a faster rate, as shown by more severe nephritis and elevated pathogenic autoantibodies compared to their counterparts born to wild-type dams. When immune competent pups were cross fostered onto AID-deficient dams, these mice exhibited more severe disease characteristics, including exacerbated lupus nephritis, increased levels of circulating antinuclear antibodies, and more activated T cells. These results suggest that a protective antibody effect contributes to the modulation of SLE progression in postnatal period. Overall, these findings highlight the importance of maternal antibodies in programming the immune system and altering SLE development in offspring.

GBP5 Inhibition Ameliorates the Progression of Lupus Nephritis by Suppressing NLRP3 Inflammasome Activation

BACKGROUND

The inflammatory response and NLRP3 inflammasome activation are typical characteristics of lupus nephritis (LN). Guanylate-binding protein 5 (GBP5) has effects on the release of proinflammatory cytokines and the activation of NLRP3 inflammasome. However, it is largely unknown whether and how GBP5 contributes to the progression of LN.

METHODS

To detect the role of GBP5 in LN, MRL/lpr mice were administrated with the lentiviral vectors that knockdown GBP5 via tail vein. Proximal tubular epithelial HK-2 cells were treated with LPS and ATP to mimic the inflammatory response of LN in vitro.

RESULTS

GBP5 expression was increased in the renal cortical tissues of LN mice. The in vivo results showed that GBP5 inhibition prevented the progression of LN, as evidenced by the decreased levels of 24-hour proteinuria, blood urea nitrogen and creatinine, accompanied by the ameliorated renal pathological damages. The increased mRNA and protein levels of proinflammatory factors (IL-6, TNF-α, iNOS and COX-2) in the renal cortex of LN mice were suppressed by GBP5 knockdown. In vitro, we demonstrated that the treatment of LPS combined with ATP induced an increase in GBP5 mRNA and protein expression in HK-2 cells. Mechanically, knockdown of GBP5 inhibited the activation of NLRP3 inflammasome and the secretion of IL-1β and IL-18 both in vivo and in vitro.

CONCLUSION

Our findings reveal that GBP5 inhibition prevents the progression of LN, most likely by suppressing NLRP3 inflammasome activation. It provides a novel insight into the therapeutic interventions for LN.

Endothelin receptor antagonism improves glucose tolerance and adipose tissue inflammation in an experimental model of systemic lupus erythematosus

Endothelin-1 (ET-1) is elevated in patients with systemic lupus erythematosus (SLE), an autoimmune disease characterized by high rates of hypertension, renal injury, and cardiovascular disease. SLE is also associated with an increased prevalence of obesity and insulin resistance compared to the general population. In the present study, we tested the hypothesis that elevated ET-1 in SLE contributes to obesity and insulin resistance. For these studies, we used the NZBWF1 mouse model of SLE, which develops obesity and insulin resistance on a normal chow diet. To test this hypothesis, we treated control (NZW) and SLE (NZBWF1) mice with vehicle, atrasentan (ETA receptor antagonist, 10 mg/kg/day), or bosentan (ETA/ETB receptor antagonist, 100 mg/kg/day) for 4 wk. Neither treatment impacted circulating immunoglobulin levels, but treatment with bosentan lowered anti-dsDNA IgG levels, a marker of SLE disease activity. Treatment with atrasentan and bosentan decreased glomerulosclerosis, and atrasentan lowered renal T-cell infiltration. Body weight was lower in SLE mice treated with atrasentan or bosentan. Endothelin receptor antagonism also improved hyperinsulinemia, homeostatic model assessment for insulin resistance, and glucose tolerance in SLE mice. Adipose tissue inflammation was also improved by endothelin receptor blockade. Taken together, these data suggest a potential therapeutic benefit for SLE patients with obesity and insulin resistance.NEW & NOTEWORTHY SLE is an autoimmune disease that is associated with obesity, insulin resistance, and elevated endothelin-1. The present study demonstrated that pharmacological inhibition of endothelin receptors decreased body weight, insulin resistance, and adipose tissue inflammation in a murine model of SLE. The therapeutic potential of endothelin receptor antagonists to treat obesity-related diseases and pathophysiological conditions, such as autoimmune diseases and insulin resistance, has become increasingly clear.

Systemic blockade of proBDNF inhibited the expansion and altered the transcriptomic expression in CD3+B220+ cells in MRL/lpr lupus mice

OBJECTIVES

The overexpansion of CD3⁺B220⁺ cells is the hallmark and main pathological mechanism of clinical manifestations of spontaneously developed MRL/lpr mice, which are primarily used as a mouse model of SLE. Our recent report demonstrated that blocking brain-derived neurotrophic factor precursor (proBDNF) suppressed the antibody-secreting cell differentiation and proliferation and inhibited the progression of SLE; however, the effect of proBDNF blockade on these CD3⁺B220⁺ cells in MRL/lpr mice is unclear.

METHODS

To explore the effect of proBDNF on CD3⁺B220⁺ cells, MRL/lpr mice at 12 weeks old were intraperitoneally injected with monoclonal anti-proBDNF antibody (McAb-proB) or control IgG continuously for 8 weeks. The manifestations in mice were observed, and peripheral blood and splenocytes were collected and analysed via flow cytometry at 20 weeks old. In addition, splenic CD3⁺B220⁺ cells were subjected to RNA sequencing (RNA-seq) analysis to identify transcriptomic alterations.

RESULTS

CD3⁺B220⁺ cells in peripheral blood (p=0.0101) and spleen (p<0.0001) were expanded in MRL/lpr mice. Meanwhile, inhibition of proBDNF signalling reduced the percentage of CD3⁺B220⁺ cells in peripheral blood (p=0.0036) and spleen (p=0.0280), alleviated lymphadenopathy, reduced urine protein level (p<0.0001) and increased the body weight (p=0.0493). RNA-seq revealed 501 upregulated and 206 downregulated genes in splenic CD3⁺B220⁺ cells in McAb-proB-treated MRL/lpr mice compared with IgG-treated mice. The differentially expressed genes were found to be involved in apoptosis, tumour necrosis factor signalling, and T cell differentiation and proliferation.

CONCLUSION

Systemic blockade of proBDNF inhibited the overexpansion of CD3⁺B220⁺ cells and altered their signals related to cell cycle, cell apoptosis and the immune response, which may contribute to the attenuation of disease symptoms in murine lupus.

Development of a novel Poly (I:C)-induced murine model with accelerated lupus nephritis and examination of the therapeutic effects of mycophenolate mofetil and a cathepsin S inhibitor

Systemic lupus erythematosus (SLE) is an autoimmune disease involving multi-organ systems with a widely heterogeneous clinical presentation. Renal involvement, observed mainly in lupus nephritis (LN), is the most common organ lesion associated with SLE and a determinant of prognosis. However, treatment of LN remains controversial and challenging, prompting the need for novel therapeutic approaches. In particular, development of a clinically relevant LN animal model would greatly facilitate the development of new treatments. Here, we report a novel murine model for LN established by administering polyinosinic-polycytidylic acid (Poly (I:C)) to NZB/W F1 mice. We investigated the effectiveness of administering Poly (I:C) to NZB/W F1 mice for accelerating nephritis onset and explored the optimal conditions under which to enroll mice with nephritis with similar pathology for studying treatment candidates. Gene-expression analysis revealed that activation of macrophages, which are reported to be involved in the progression of LN in patients, was a unique characteristic in this accelerated nephritis model. Evaluation of the therapeutic effect of mycophenolate mofetil (MMF), a recommended first-choice agent for LN, in this novel LN model showed that MMF significantly reduced proteinuria. The cathepsin S (CatS) inhibitor ASP1617, which has been reported to prevent development of lupus-like glomerulonephritis in the spontaneous NZB/W F1 mouse model, also showed marked therapeutic effect in this model. Our novel Poly (I:C) accelerated LN model would thus be very useful for screening clinical candidates for LN, and CatS may be an attractive therapeutic target for the treatment of LN.

Renal TLR-7/TNF-α pathway as a potential female-specific mechanism in the pathogenesis of autoimmune-induced hypertension

Hypertension is prevalent in patients with systemic lupus erythematosus (SLE). The goal of the current study is to track the pathogenesis of hypertension and renal injury in SLE, identify contributory mechanisms, and highlight differences in disease development among sexes. Mean arterial pressure was measured in conscious male and female SLE (NZBWF1) and control (NZW) mice at 34-35 wk of age using indwelling arterial catheters. Measures of renal injury, renal inflammation, and renal hemodynamics were used to monitor the potential contributors to latent sex differences. Both male and female SLE mice were hypertensive at 35 wk of age, and the hypertension was linked to renal injury in females, but not in males. A known contributor of renal pathology in SLE, Toll-like receptor (TLR)-7, and its downstream effector, the proinflammatory cytokine tumor necrosis factor (TNF)-α, were lower in male SLE mice than in females. Male SLE mice also had higher glomerular filtration rate (GFR) and lower renal vascular resistance (RVR) than females. Our data suggest that although hypertension in female SLE mice is associated with renal mechanisms, hypertension in male SLE mice may develop independent of renal changes. Future studies will continue to dissect sex-specific factors that should be considered when treating patients with hypertension with underlying chronic inflammation and/or autoimmunity.NEW & NOTEWORTHY There is a high prevalence of hypertension in male and female SLE; however, male SLE mice are hypertensive without renal involvement. The development of hypertension in female SLE mice is renocentric and strongly associated with injurious renal mechanisms like the TLR-7→TNF-α pathway. This clear difference in the pathogenesis among the sexes could have a significant impact on how we treat patients with hypertension with underlying chronic autoimmune/inflammatory diseases.

The anti-inflammatory effects of Hedyotis diffusa Willd on SLE with STAT3 as a key target

ETHNOPHARMACOLOGICAL RELEVANCE

Hedyotis diffusa Willd, also named Scleromitrion diffusum (Willd.) R.J. Wang, is one medical herb, which has been traditionally used by the She nationality in China. And H. diffusa represents a beneficial effect on Systemic lupus erythematosus (SLE) treatment in clinic.

AIM OF THE STUDY

The underlying mechanisms of the protective effects of H. diffusa on SLE remain unclear. In this study, we treated MRL/lpr mice with H. diffusa water extract (HDW) to assess its therapeutic effects and verified its regulating signalling pathway through cytological experiments.

MATERIALS AND METHODS

In the present study, the constituents of HDW were analysed through ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) and SCIEX OS software. The protective activity and underlying mechanisms were studied in a MRL/lpr lupus mouse model. The blood cells, autoantibodies, metabolites and the cytokines in serum were identified with a hematology analyzer, specific ELISA kit, GC/MS system and cytometric assays. The histological and immunohistochemical analysis were engaged in the morphologic, and the expression and translocation of the crucial protein observation. The dual luciferase reporter assay was applied to identifying the regulative activity of HDW. The transcription and translation expression of the protein was studied by real-time PCR and Western blot assays. The network pharmacology analysis was employed to predict the IL-6/STAT3 pathway regulators and the screen the STAT3 inhibitors in HDW.

RESULTS

The results revealed the capability of HDW to attenuate the production of autoantibodies, secretion of inflammatory cytokines (IL-6 and IFN-γ), and suppressed the IgG and C3 deposition, the development of glomerular lesions in MRL/lpr mice. Serum metabolomics study showed the improvement in serum metabolites, especially aminoacyl-tRNA biosynthesis, by HDW. IL-6 was clarified to be highly associated with the significantly changed metabolites in network analysis. We further demonstrated the effects of HDW on the IL-6/STAT3 pathway in vivo and in vitro.

CONCLUSIONS

This study suggested that HDW exerts a therapeutic effect in SLE model mice by suppressing the IL-6/STAT3 pathway.

Quercetin Ameliorates Renal Injury and Pyroptosis in Lupus Nephritis through Inhibiting IL-33/ST2 Pathway In Vitro and In Vivo

Lupus nephritis (LN) is a common and serious symptom in patients with systemic lupus erythematosus (SLE). Tubular interstitial fibrosis is a common underlying mechanism in the development of lupus nephritis to end-stage renal failure (ESRD). Quercetin is widely proven to prevent tissue fibrosis. Therefore, the purpose of this study is to investigate the beneficial effects of quercetin on the inhibition of fibrosis and inflammation pathways in in vitro and in vivo lupus nephritis models. In the current study, MRL/lpr mice as animal models, and HK-2 human renal tubular epithelial cells were stimulated by interleukin-33 (IL-33) to mimic the cellular model of lupus nephritis. Immunohistochemical staining, immunoblotting assay, immunofluorescence staining, and quantitative real-time polymerase chain reaction assay were used. The in vivo results showed that quercetin improved the renal function and inhibited both fibrosis- and inflammation-related markers in MRL/lpr mice animal models. The in vitro results indicated that quercetin ameliorated the accumulation of fibrosis- and inflammation-related proteins in IL-33-induced HK-2 cells and improved renal cell pyroptosis via the IL33/ST2 pathway. Overall, quercetin can improve LN-related renal fibrosis and inflammation, which may offer an effective potential therapeutic strategy for lupus nephritis.

The role of type I IFN in autoimmune and autoinflammatory diseases with CNS involvement

Type I interferons (IFNs) are major mediators of innate immunity, with well-known antiviral, antiproliferative, and immunomodulatory properties. A growing body of evidence suggests the involvement of type I IFNs in the pathogenesis of central nervous system (CNS) manifestations in the setting of chronic autoimmune and autoinflammatory disorders, while IFN-β has been for years, a well-established therapeutic modality for multiple sclerosis (MS). In the present review, we summarize the current evidence on the mechanisms of type I IFN production by CNS cellular populations as well as its local effects on the CNS. Additionally, the beneficial effects of IFN-β in the pathophysiology of MS are discussed, along with the contributory role of type I IFNs in the pathogenesis of neuropsychiatric lupus erythematosus and type I interferonopathies.

Effects of high fat diet-induced obesity on pathophysiology, immune cells, and therapeutic efficacy in systemic lupus erythematosus

Prior studies have suggested a strong link between obesity and autoimmune diseases. This study aimed to evaluate the effects of high fat diet (HFD)-induced obesity on the disease pathogenesis, immune cell infiltration, and therapeutic efficacy in systemic lupus erythematosus (SLE). Treatment with methylprednisolone significantly increased the survival in the control diet group, but not in the HFD group. An HFD significantly increased the incidence of severe proteinuria and glucose intolerance. Regardless of the diet, treatment with methylprednisolone significantly decreased the serum levels of anti-dsDNA antibodies, IL-2, IL-10, and interferon γ-induced protein 10 (IP-10), and improved the renal pathology scores. Treatment with methylprednisolone significantly lowered the serum levels of IL-6, MCP-1, and TNF-α in the control diet group, but not in the HFD group. HFD significantly increased the proportions of CD45⁺ and M1 cells and significantly decreased the proportion of M2 cells in white adipose tissue; methylprednisolone treatment significantly rescued this effect. In the HFD group, methylprednisolone treatment significantly decreased the M1:M2 and increased the Foxp3⁺:RORγt⁺ cell in the spleen compared with the untreated group. These data improve our understanding of the effect of HFD on the therapeutic efficacy of corticosteroids in SLE treatment, which could have clinical implications.

Comparative effects of human-equivalent low, moderate, and high dose oral prednisone intake on autoimmunity and glucocorticoid-related toxicity in a murine model of environmental-triggered lupus

Autoimmune diseases can be triggered by environmental toxicants such as crystalline silica dust (cSiO2). Here, we characterized the dose-dependent immunomodulation and toxicity of the glucocorticoid (GC) prednisone in a preclinical model that emulates onset and progression of cSiO2-triggered lupus. Two cohorts of 6-wk-old female NZBWF1 mice were fed either control AIN-93G diet or one of three AIN-93G diets containing prednisone at 5, 15, or 50 mg/kg diet which span human equivalent oral doses (HED) currently considered to be low (PL; 5 mg/d HED), moderate (PM; 14 mg/d HED), or high (PH; 46 mg/d HED), respectively. At 8 wk of age, mice were intranasally instilled with either saline vehicle or 1 mg cSiO2 once weekly for 4 wk. The experimental plan was to 1) terminate one cohort of mice (n=8/group) 14 wk after the last cSiO2 instillation for pathology and autoimmunity assessment and 2) to maintain a second cohort (n=9/group) to monitor glomerulonephritis development and survival. Mean blood concentrations of prednisone's principal active metabolite, prednisolone, in mice fed PL, PM, and PH diets were 27, 105, 151 ng/ml, respectively, which are consistent with levels observed in human blood ≤ 12 h after single bolus treatments with equivalent prednisone doses. Results from the first cohort revealed that consumption of PM, but not PL diet, significantly reduced cSiO2-induced pulmonary ectopic lymphoid structure formation, nuclear-specific AAb production, inflammation/autoimmune gene expression in the lung and kidney, splenomegaly, and glomerulonephritis in the kidney. Relative to GC-associated toxicity, PM diet, but not PL diet, elicited muscle wasting, but these diets did not affect bone density or cause glucosuria. Importantly, neither PM nor PL diet improved latency of cSiO2-accelerated death. PH-fed mice in both cohorts displayed robust GC-associated toxicity including body weight loss, reduced muscle mass, and extensive glucosuria 7 wk after the final cSiO2 instillation requiring their early removal from the study. Taken together, our results demonstrate that while moderate doses of prednisone can reduce important pathological endpoints of cSiO2-induced autoimmunity in lupus-prone mice, such as upstream ectopic lymphoid structure formation, these ameliorative effects come with unwanted GC toxicity, and, crucially, none of these three doses extended survival time.

P2X7 purinergic receptor plays a critical role in maintaining T-cell homeostasis and preventing lupus pathogenesis

The severe lymphoproliferative and lupus diseases developed by MRL/lpr mice depend on interactions between the Fas^lpr mutation and MRL genetic background. Thus, the Fas^lpr mutation causes limited disease in C57BL/6 mice. We previously found that accumulating B220⁺ CD4^–CD8^– double negative (DN) T cells in MRL/lpr mice show defective P2X7 receptor ( P2X7)-induced cellular functions, suggesting that P2X7 contributes to T-cell homeostasis, along with Fas. Therefore, we generated a B6/lpr mouse strain (called B6/lpr-p2x7KO) carrying homozygous P2X7 knockout alleles. B6/lpr-p2x7KO mice accumulated high numbers of FasL-expressing B220⁺ DN T cells of CD45RB^highCD44^high effector/memory CD8⁺ T-cell origin and developed severe lupus, characterized by leukocyte infiltration into the tissues, high levels of IgG anti-dsDNA and rheumatoid factor autoantibodies, and marked cytokine network dysregulation. B6/lpr-p2x7KO mice also exhibited a considerably reduced lifespan. P2X7 is therefore a novel regulator of T-cell homeostasis, of which cooperation with Fas is critical to prevent lymphoaccumulation and autoimmunity.

Polymeric dexamethasone prodrugs attenuate lupus nephritis in MRL/lpr mice with reduced glucocorticoid toxicity

Due to their potent immunosuppressive and anti-inflammatory effects, glucocorticoids (GCs) are the most widely used medications in treating lupus nephritis (LN). Long-term use of GCs, however, is associated with numerous off-target adverse effects. To reduce GCs' adverse effects, we previously developed two polymeric dexamethasone prodrug nanomedicines: N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer-based dexamethasone prodrug (P-Dex), and micelle-forming polyethylene glycol (PEG)-based dexamethasone prodrug (ZSJ-0228). Both P-Dex and ZSJ-0228 provided sustained amelioration of LN in lupus-prone NZB/W F1 mice with reduced GC-associated adverse effects. Here, we have extended our investigation to the MRL/lpr mouse model of LN. Compared to dose equivalent daily dexamethasone sodium phosphate (Dex) treatment, monthly P-Dex or ZSJ-0228 treatments were more effective in reducing proteinuria and extending the lifespan of MRL/lpr mice. Unlike the daily Dex treatment, ZSJ-0228 was not associated with measurable GC-associated adverse effects. In contrast, adrenal gland atrophy was observed in P-Dex treated mice.

Human umbilical cord mesenchymal stem cells derived extracellular vesicles regulate acquired immune response of lupus mouse in vitro

Systemic lupus erythematosus (SLE) is an autoimmune disease involving multiple systems. Immunopathology believes that abnormal T cell function and excessive production of autoantibodies by B cells are involved in multi-organ damage. Human umbilical cord mesenchymal stem cells (hUCMSCs) therapies have endowed with promise in SLE, while the function of MSC-derived extracellular vesicles (MSC-EVs) was still unclear. Extracellular vesicles (EVs) are subcellular components secreted by a paracellular mechanism and are essentially a group of nanoparticles. EVs play a vital role in cell-to-cell communication by acting as biological transporters. New evidence has shown beneficial effects of MSC-EVs on autoimmune diseases, such as their immunomodulatory properties. In this study, we investigated whether hUCMSCs derived extracellular vesicles (hUCMSC-EVs) could regulate abnormal immune responses of T cells or B cells in SLE. We isolated splenic mononuclear cells from MRL/lpr mice, a classical animal model of SLE. PBS (Phosphate-buffered saline), 2 × 10⁵ hUCMSCs, 25 µg/ml hUCMSC-EVs, 50 µg/ml hUCMSC-EVs were co-cultured with 2 × 10⁶ activated splenic mononuclear cells for 3 days in vitro, respectively. The proportions of CD4⁺ T cell subsets, B cells and the concentrations of cytokines were detected. Both hUCMSCs and hUCMSC-EVs inhibited CD4⁺ T cells, increased the production of T helper (Th)17 cells, promoted the production of interleukin (IL)-17 and transforming growth factor beta1 (TGF-β1) (P < 0.05), although they had no significant effects on Th1, Th2, T follicular helper (Tfh), regulatory T (Treg) cells and IL-10 (P > 0.05); only hUCMSCs inhibited CD19⁺ B cells, promoted the production of interferon-gamma (IFN-γ) and IL-4 (P < 0.05). hUCMSCs exert immunoregulatory effects on SLE at least partially through hUCMSC-EVs in vitro, therefore, hUCMSC-EVs play novel and potential regulator roles in SLE.

Dual Costimulatory and Coinhibitory Targeting with a Hybrid Fusion Protein as an Immunomodulatory Therapy in Lupus Nephritis Mice Models

Systemic lupus erythematosus is a complex autoimmune disorder mostly mediated by B-cells in which costimulatory signals are involved. This immune dysregulation can cause tissue damage and inflammation of the kidney, resulting in lupus nephritis and chronic renal failure. Given the previous experience reported with CTLA4-Ig as well as recent understanding of the PD-1 pathway in this setting, our group was encouraged to evaluate, in the NZBWF1 model, a human fusion recombinant protein (Hybri) with two domains: CTLA4, blocking the CD28—CD80 costimulatory pathway, and PD-L2, exacerbating the PD-1–PD-L2 coinhibitory pathway. After achieving good results in this model, we decided to validate the therapeutic effect of Hybri in the more severe MRL/lpr model of lupus nephritis. The intraperitoneal administration of Hybri prevented the progression of proteinuria and anti-dsDNA antibodies to levels like those of cyclophosphamide and reduced the histological score, infiltration of B-cells, T-cells, and macrophages and immune deposition in both lupus-prone models. Additionally, Hybri treatment produced changes in both inflammatory-related circulating cytokines and kidney gene expression. To summarize, both in vivo studies revealed that the Hybri effect on costimulatory-coinhibitory pathways may effectively mitigate lupus nephritis, with potential for use as a maintenance therapy.

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.

Liposomes Bearing Non-Bilayer Phospholipid Arrangements Induce Specific IgG Anti-Lipid Antibodies by Activating NK1.1+, CD4+ T Cells in Mice

Liposomes are artificial models of cellular membranes that are used as delivery systems for genes, drugs and protein antigens. We have previously used them to study the antigenic properties of their phospholipids. Here, we used them to induce the production of IgG anti-non-bilayer phospholipid arrangements (NPAs) antibodies in mice; these antibodies cause cell lysis and trigger a lupus-like disease in mice. We studied the mechanisms that lead to the production of these antibodies, and provide evidence that NK1.1⁺, CD4⁺ T cells respond to NPA-bearing liposomes and deliver the help required for specific B cell activation and antibody class-switching to IgG. We found increased numbers of IL-4-producing NK1.1⁺, CD4⁺ T cells in the secondary lymphoid organs of mice administered with NPAs, and these cells also expressed CD40L, which is required for B cell activation. Additionally, we isolated and purified NK1.1⁺, CD4⁺ T cells from spleens and determined that they over-expressed 40 genes, which are key players in inflammatory processes and B cell stimulation and have TRAF6 and UNC39B1 as key nodes in their network. These results show that liposomes are membrane models that can be used to analyze the immunogenicity of lipids.

Lactobacillus: Friend or Foe for Systemic Lupus Erythematosus?

The cause of Systemic Lupus Erythematosus (SLE) remains largely unknown, despite the fact that it is well understood that a complex interaction between genes and environment is required for disease development. Microbiota serve as activators and are essential to immune homeostasis. Lactobacillus is thought to be an environmental agent affecting the development of SLE. However, beneficial therapeutic and anti-inflammatory effects of Lactobacillus on SLE were also explored. The discovery of Lactobacillus involvement in SLE will shed light on how SLE develops, as well as finding microbiota-targeted biomarkers and novel therapies. In this review, we attempt to describe the two sides of Lactobacillus in the occurrence, development, treatment and prognosis of SLE. We also discuss the effect of different strains Lactobacillus on immune cells, murine lupus, and patients. Finally, we try to illustrate the potential immunological mechanisms of Lactobacillus on SLE and provide evidence for further microbiota-targeted therapies.

The Ameliorative Effect of Dexamethasone on the Development of Autoimmune Lung Injury and Mediastinal Fat-Associated Lymphoid Clusters in an Autoimmune Disease Mouse Model

In our previous study, we revealed the ameliorative therapeutic effect of dexamethasone (Dex) for Lupus nephritis lesions in the MRL/MpJ-Fas ^lpr/lpr (Lpr) mouse model. The female Lpr mice developed a greater number of mediastinal fat-associated lymphoid clusters (MFALCs) and inflammatory lung lesions compared to the male mice. However, the effect of Dex, an immunosuppressive drug, on both lung lesions and the development of MFALCs in Lpr mice has not been identified yet. Therefore, in this study, we compared the development of lung lesions and MFALCs in female Lpr mice that received either saline (saline group “SG”) or dexamethasone (dexamethasone group “DG”) in drinking water as a daily dose along with weekly intraperitoneal injections for 10 weeks. Compared to the SG group, the DG group showed a significant reduction in the levels of serum anti-dsDNA antibodies, the size of MFALCs, the degree of lung injury, the area of high endothelial venules (HEVs), and the number of proliferating and immune cells in both MFALCs and the lungs. A significant positive correlation was observed between the size of MFALCs and the cellular aggregation in the lungs of Lpr mice. Therefore, this study confirmed the ameliorative effect of Dex on the development of lung injury and MFALCs via their regressive effect on both immune cells’ proliferative activity and the development of HEVs. Furthermore, the reprogramming of MFALCs by targeting immune cells and HEVs may provide a therapeutic strategy for autoimmune-disease-associated lung injury.

Vascular Inflammation in Mouse Models of Systemic Lupus Erythematosus

Vascular inflammation mediated by overly activated immune cells is a significant cause of morbidity and mortality in systemic lupus erythematosus (SLE). Several mouse models to study the pathogenesis of SLE are currently in use, many of which have different mechanisms of pathogenesis. The diversity of these models allows interrogation of different aspects of the disease pathogenesis. To better determine the mechanisms by which vascular inflammation occurs in SLE, and to assist future researchers in choosing the most appropriate mouse models to study cardiovascular complications in SLE, we suggest that direct comparisons of vascular inflammation should be conducted among different murine SLE models. We also propose the use of in vitro vascular assays to further investigate vascular inflammation processes prevalent among different murine SLE models.

Therapeutic approaches targeting CD95L/CD95 signaling in cancer and autoimmune diseases

Cell death plays a pivotal role in the maintenance of tissue homeostasis. Key players in the controlled induction of cell death are the Death Receptors (DR). CD95 is a prototypic DR activated by its cognate ligand CD95L triggering programmed cell death. As a consequence, alterations in the CD95/CD95L pathway have been involved in several disease conditions ranging from autoimmune diseases to inflammation and cancer. CD95L-induced cell death has multiple roles in the immune response since it constitutes one of the mechanisms by which cytotoxic lymphocytes kill their targets, but it is also involved in the process of turning off the immune response. Furthermore, beyond the canonical pro-death signals, CD95L, which can be membrane-bound or soluble, also induces non-apoptotic signaling that contributes to its tumor-promoting and pro-inflammatory roles. The intent of this review is to describe the role of CD95/CD95L in the pathophysiology of cancers, autoimmune diseases and chronic inflammation and to discuss recently patented and emerging therapeutic strategies that exploit/block the CD95/CD95L system in these diseases.

The Anti-DNA Antibodies: Their Specificities for Unique DNA Structures and Their Unresolved Clinical Impact-A System Criticism and a Hypothesis

Systemic lupus erythematosus (SLE) is diagnosed and classified by criteria, or by experience, intuition and traditions, and not by scientifically well-defined etiology(ies) or pathogenicity(ies). One central criterion and diagnostic factor is founded on theoretical and analytical approaches based on our imperfect definition of the term “The anti-dsDNA antibody”. “The anti-dsDNA antibody” holds an archaic position in SLE as a unique classification criterium and pathogenic factor. In a wider sense, antibodies to unique transcriptionally active or silent DNA structures and chromatin components may have individual and profound nephritogenic impact although not considered yet – not in theoretical nor in descriptive or experimental contexts. This hypothesis is contemplated here. In this analysis, our state-of-the-art conception of these antibodies is probed and found too deficient with respect to their origin, structural DNA specificities and clinical/pathogenic impact. Discoveries of DNA structures and functions started with Miescher’s Nuclein (1871), via Chargaff, Franklin, Watson and Crick, and continues today. The discoveries have left us with a DNA helix that presents distinct structures expressing unique operations of DNA. All structures are proven immunogenic! Unique autoimmune antibodies are described against e.g. ssDNA, elongated B DNA, bent B DNA, Z DNA, cruciform DNA, or individual components of chromatin. In light of the massive scientific interest in anti-DNA antibodies over decades, it is an unexpected observation that the spectrum of DNA structures has been known for decades without being implemented in clinical immunology. This leads consequently to a critical analysis of historical and contemporary evidence-based data and of ignored and one-dimensional contexts and hypotheses: i.e. “one antibody - one disease”. In this study radical viewpoints on the impact of DNA and chromatin immunity/autoimmunity are considered and discussed in context of the pathogenesis of lupus nephritis.

Axl regulated survival/proliferation network and its therapeutic intervention in mouse models of glomerulonephritis

BACKGROUND

Lupus nephritis (LN) is the most common and serious complication of systemic lupus erythematosus (SLE). LN pathogenesis is not fully understood. Axl receptor tyrosine kinase is upregulated and contributes to the pathogenic progress in LN. We have reported that Axl disruption attenuates nephritis development in mice.

METHODS

In this study, we analyzed the gene expression profiles with RNA-seq using renal cortical samples from nephritic mice. Axl-KO mice were bred onto a B6.lpr spontaneous lupus background, and renal disease development was followed and compared to the Axl-sufficient B6.lpr mice. Finally, anti-glomerular basement membrane (anti-GBM) Ab-induced nephritic mice were treated with Axl small molecule inhibitor, R428, at different stages of nephritis development. Blood urine nitrogen levels and renal pathologies were evaluated.

RESULTS

Transcriptome analysis revealed that renal Axl activation contributed to cell proliferation, survival, and motility through regulation of the Akt, c-Jun, and actin pathways. Spontaneous lupus-prone B6.lpr mice with Axl deficiency showed significantly reduced kidney damages and decreased T cell infiltration compared to the renal damage and T cell infiltration in Axl-sufficient B6.lpr mice. The improved kidney function was independent of autoAb production. Moreover, R428 significantly reduced anti-GBM glomerulonephritis at different stages of GN development compared to the untreated nephritic control mice. R428 administration reduced inflammatory cytokine (IL-6) production, T cell infiltration, and nephritis disease activity.

CONCLUSIONS

Results from this study emphasize the important role of Axl signaling in LN and highlight Axl as an attractive target in LN.

Deep Learning-Based Model Significantly Improves Diagnostic Performance for Assessing Renal Histopathology in Lupus Glomerulonephritis

<b><i>Background:</i></b> Assessment of glomerular lesions and structures plays an essential role in understanding the pathological diagnosis of glomerulonephritis and prognostic evaluation of many kidney diseases. Renal pathophysiological assessment requires novel high-throughput tools to conduct quantitative, unbiased, and reproducible analyses representing a central readout. Deep learning may be an effective tool for glomerulonephritis pathological analysis. <b><i>Methods:</i></b> We developed a murine renal pathological system (MRPS) model to objectify the pathological evaluation via the deep learning method on whole-slide image (WSI) segmentation and feature extraction. A convolutional neural network model was used for accurate segmentation of glomeruli and glomerular cells of periodic acid-Schiff-stained kidney tissue from healthy and lupus nephritis mice. To achieve a quantitative evaluation, we subsequently filtered five independent predictors as image biomarkers from all features and developed a formula for the scoring model. <b><i>Results:</i></b> Perimeter, shape factor, minimum internal diameter, minimum caliper diameter, and number of objects were identified as independent predictors and were included in the establishment of the MRPS. The MRPS showed a positive correlation with renal score (<i>r</i> = 0.480, <i>p</i> &#x3c; 0.001) and obtained great diagnostic performance in discriminating different score bands (Obuchowski index, 0.842 [95% confidence interval: 0.759, 0.925]), with an area under the curve of 0.78–0.98, sensitivity of 58–93%, specificity of 72–100%, and accuracy of 74–94%. <b><i>Conclusion:</i></b> Our MRPS for quantitative assessment of renal WSIs from MRL/lpr lupus nephritis mice enables accurate histopathological analyses with high reproducibility, which may serve as a useful tool for glomerulonephritis diagnosis and prognosis evaluation.

Therapeutic potential of triptolide in autoimmune diseases and strategies to reduce its toxicity

With the increasing epidemiology of autoimmune disease worldwide, there is an urgent need for effective drugs with low cost in clinical treatment. Triptolide, the most potent bioactive compound from traditional Chinese herb Tripterygium Wilfordii Hook F, possesses immunosuppression and anti-inflammatory activity. It is a potential drug for the treatment of various autoimmune diseases, but its clinical application is still restricted due to severe toxicity. In this review, the pharmacodynamic effects and pharmacological mechanisms of triptolide in autoimmune diseases are summarized. Triptolide exerts therapeutic effect by regulating the function of immune cells and the expression of cytokines through inflammatory signaling pathways, as well as maintaining redox balance and gut microbiota homeostasis. Meanwhile, the research progress on toxicity of triptolide to liver, kidney, reproductive system, heart, spleen, lung and gastrointestinal tract has been systematically reviewed. In vivo experiments on different animals and clinical trials demonstrate the dose- and time- dependent toxicity of triptolide through different administration routes. Furthermore, we focus on the strategies to reduce toxicity of triptolide, including chemical structural modification, novel drug delivery systems, and combination pharmacotherapy. This review aims to reveal the potential therapeutic prospect and limitations of triptolide in treating autoimmune diseases, thus providing guiding suggestions for further study and promoting its clinical translation.