A Novel Human Interleukin-23A Overexpressing Mouse Model of Systemic Lupus Erythematosus.

OBJECTIVE: Interleukin-23 (IL-23) is a crucial cytokine implicated in chronic inflammation and autoimmunity, associated with various diseases such as psoriasis, psoriatic arthritis, and systemic lupus erythematosus (SLE). This study aimed to create and characterize a transgenic mouse model overexpressing human IL-23A (TghIL-23A), providing a valuable tool for investigating the pathogenic role of human IL-23A and evaluating the efficacy of anti-human IL-23A therapeutics. METHODS: TghIL-23A mice were generated via microinjection of CBA × C57BL/6 zygotes with a fragment of the human IL23A gene, flanked by its 5'-regulatory sequences and the 3' untranslated region of human ß-globin. The TghIL-23A pathology was assessed through hematologic and biochemic analyses, cytokine and antinuclear antibody detection, and histopathologic examination of skin and renal tissues. The response to the anti-human IL-23A therapeutic agent guselkumab was evaluated in groups of eight mixed-sex mice receiving subcutaneous treatment twice weekly for 10 weeks using clinical, biomarker, and histopathologic readouts. RESULTS: TghIL-23A mice exhibited interactions between human IL-23A and mouse IL-23/IL-12p40 and developed a chronic multiorgan autoimmune disease marked by proteinuria, anti-double-stranded DNA antibodies, severe inflammatory lesions in the skin, and milder phenotypes in the kidneys and lungs. The TghIL-23A pathologic features exhibited significant similarities to those observed in human patients with SLE, and they were reversed following guselkumab treatment. CONCLUSION: We have generated and characterized a novel genetic mouse model of SLE, providing proof-of-concept for the etiopathogenic role of human IL-23A. This new model has a normal life span and integrates several characteristics of the human disease's complexity and chronicity, making it an attractive preclinical tool for studying IL-23-dependent pathogenic mechanisms and assessing the efficacy of anti-human IL-23A or modeled disease-related therapeutics.

Repurposing the antipsychotic drug amisulpride for targeting synovial fibroblast activation in arthritis.

Synovial fibroblasts (SFs) are key pathogenic drivers in rheumatoid arthritis (RA). Their in vivo activation by TNF is sufficient to orchestrate full arthritic pathogenesis in animal models, and TNF blockade proved efficacious for a high percentage of patients with RA albeit coinducing rare but serious side effects. Aiming to find new potent therapeutics, we applied the L1000CDS2 search engine, to repurpose drugs that could reverse the pathogenic expression signature of arthritogenic human TNF-transgenic (hTNFtg) SFs. We identified a neuroleptic drug, namely amisulpride, which reduced SFs' inflammatory potential while decreasing the clinical score of hTNFtg polyarthritis. Notably, we found that amisulpride function was neither through its known targets dopamine receptors D2 and D3 and serotonin receptor 7 nor through TNF-TNF receptor I binding inhibition. Through a click chemistry approach, potentially novel targets of amisulpride were identified, which were further validated to repress hTNFtg SFs' inflammatory potential ex vivo (Ascc3 and Sec62), while phosphoproteomics analysis revealed that treatment altered important fibroblast activation pathways, such as adhesion. Thus, amisulpride could prove beneficial to patients experiencing RA and the often-accompanying comorbid dysthymia, reducing SF pathogenicity along with its antidepressive activity, serving further as a "lead" compound for the development of novel therapeutics against fibroblast activation.

Combination of subtherapeutic anti-TNF dose with dasatinib restores clinical and molecular arthritogenic profiles better than standard anti-TNF treatment.

BACKGROUND: New medications for Rheumatoid Arthritis (RA) have emerged in the last decades, including Disease Modifying Antirheumatic Drugs (DMARDs) and biologics. However, there is no known cure, since a significant proportion of patients remain or become non-responders to current therapies. The development of new mode-of-action treatment schemes involving combination therapies could prove successful for the treatment of a greater number of RA patients. METHODS: We investigated the effect of the Tyrosine Kinase inhibitors (TKIs) dasatinib and bosutinib, on the human TNF-dependent Tg197 arthritis mouse model. The inhibitors were administered either as a monotherapy or in combination with a subtherapeutic dose of anti-hTNF biologics and their therapeutic effect was assessed clinically, histopathologically as well as via gene expression analysis and was compared to that of an efficient TNF monotherapy. RESULTS: Dasatinib and, to a lesser extent, bosutinib inhibited the production of TNF and proinflammatory chemokines from arthritogenic synovial fibroblasts. Dasatinib, but not bosutinib, also ameliorated significantly and in a dose-dependent manner both the clinical and histopathological signs of Tg197 arthritis. Combination of dasatinib with a subtherapeutic dose of anti-hTNF biologic agents, resulted in a synergistic inhibitory effect abolishing all arthritis symptoms. Gene expression analysis of whole joint tissue of Tg197 mice revealed that the combination of dasatinib with a low subtherapeutic dose of Infliximab most efficiently restores the pathogenic gene expression profile to that of the healthy state compared to either treatment administered as a monotherapy. CONCLUSION: Our findings show that dasatinib exhibits a therapeutic effect in TNF-driven arthritis and can act in synergy with a subtherapeutic anti-hTNF dose to effectively treat the clinical and histopathological signs of the pathology. The combination of dasatinib and anti-hTNF exhibits a distinct mode of action in restoring the arthritogenic gene signature to that of a healthy profile. Potential clinical applications of combination therapies with kinase inhibitors and anti-TNF agents may provide an interesting alternative to high-dose anti-hTNF monotherapy and increase the number of patients responding to treatment.

Ectopic bone formation and systemic bone loss in a transmembrane TNF-driven model of human spondyloarthritis.

BACKGROUND: The transmembrane-TNF transgenic mouse, TgA86, has been shown to develop spontaneously peripheral arthritis with signs of axial involvement. To assess similarity to human spondyloarthritis, we performed detailed characterization of the axial, peripheral, and comorbid pathologies of this model. METHODS: TgA86 bone pathologies were assessed at different ages using CT imaging of the spine, tail vertebrae, and hind limbs and characterized in detail by histopathological and immunohistochemical analysis. Cardiac function was examined by echocardiography and electrocardiography and bone structural parameters by µCT analysis. The response of TgA86 mice to either early or late anti-TNF treatment was evaluated clinically, histopathologically, and by µCT analysis. RESULTS: TgA86 mice developed with 100% penetrance spontaneous axial and peripheral pathology which progressed with time and manifested as reduced body weight and body length, kyphosis, tail bendings, as well as swollen and distorted hind joints. Whole-body CT analysis at advanced ages revealed bone erosions of sacral and caudal vertebrae as well as of sacroiliac joints and hind limbs and, also, new ectopic bone formation and eventually vertebral fusion. The pathology of these mice highly resembled that of SpA patients, as it evolved through an early inflammatory phase, evident as enthesitis and synovitis in the affected joints, characterized by mesenchymal cell accumulation, and neutrophilic infiltration. Subsequently, regression of inflammation was accompanied by ectopic bone formation, leading to ankylosis. In addition, both systemic bone loss and comorbid heart valve pathology were evident. Importantly, early anti-TNF treatment, similar to clinical treatment protocols, significantly reduced the inflammatory phase of both the axial and peripheral pathology of TgA86 mice. CONCLUSIONS: The TgA86 mice develop a spontaneous peripheral and axial biphasic pathology accompanied by comorbid heart valvular dysfunction and osteoporosis, overall reproducing the progression of pathognomonic features of human spondyloarthritis. Therefore, the TgA86 mouse represents a valuable model for deciphering the role of transmembrane TNF in the pathogenic mechanisms of spondyloarthritis and for assessing the efficacy of human therapeutics targeting different phases of the disease.

Transmembrane TNF drives osteoproliferative joint inflammation reminiscent of human spondyloarthritis.

TNF plays a key role in immune-mediated inflammatory diseases including rheumatoid arthritis (RA) and spondyloarthritis (SpA). It remains incompletely understood how TNF can lead to different disease phenotypes such as destructive peripheral polysynovitis in RA versus axial and peripheral osteoproliferative inflammation in SpA. We observed a marked increase of transmembrane (tm) versus soluble (s) TNF in SpA versus RA together with a decrease in the enzymatic activity of ADAM17. In contrast with the destructive polysynovitis observed in classical TNF overexpression models, mice overexpressing tmTNF developed axial and peripheral joint disease with synovitis, enthesitis, and osteitis. Histological and radiological assessment evidenced marked endochondral new bone formation leading to joint ankylosis over time. SpA-like inflammation, but not osteoproliferation, was dependent on TNF-receptor I and mediated by stromal tmTNF overexpression. Collectively, these data indicate that TNF can drive distinct inflammatory pathologies. We propose that tmTNF is responsible for the key pathological features of SpA.

Divergent Innate and Epithelial Functions of the RNA-Binding Protein HuR in Intestinal Inflammation.

HuR is an abundant RNA-binding protein acting as a post-transcriptional regulator of many RNAs including mRNAs encoding inflammatory mediators, cytokines, death signalers and cell cycle regulators. In the context of intestinal pathologies, elevated HuR is considered to enhance the stability and the translation of pro-tumorigenic mRNAs providing the rationale for its pharmacological targeting. However, HuR also possesses specific regulatory functions for innate immunity and cytokine mRNA control which can oppose intestinal inflammation and tumor promotion. Here, we aim to identify contexts of intestinal inflammation where the innate immune and the epithelial functions of HuR converge or diverge. To address this, we use a disease-oriented phenotypic approach using mice lacking HuR either in intestinal epithelia or myeloid-derived immune compartments. These mice were compared for their responses to (a) Chemically induced Colitis; (b) Colitis- associated Cancer (CAC); (c) T-cell mediated enterotoxicity; (d) Citrobacter rodentium-induced colitis; and (e) TNF-driven inflammatory bowel disease. Convergent functions of epithelial and myeloid HuR included their requirement for suppressing inflammation in chemically induced colitis and their redundancies in chronic TNF-driven IBD and microbiota control. In the other contexts however, their functions diversified. Epithelial HuR was required to protect the epithelial barrier from acute inflammatory or infectious degeneration but also to promote tumor growth. In contrast, myeloid HuR was required to suppress the beneficial inflammation for pathogen clearance and tumor suppression. This cellular dichotomy in HuR's functions was validated further in mice engineered to express ubiquitously higher levels of HuR which displayed diminished pathologic and beneficial inflammatory responses, resistance to epithelial damage yet a heightened susceptibility to CAC. Our study demonstrates that epithelial and myeloid HuR affect different cellular dynamics in the intestine that need to be carefully considered for its pharmacological exploitation and points toward potential windows for harnessing HuR functions in intestinal inflammation.

Detection of Giardia duodenalis assemblage E infections at the Tibetan Plateau Area: Yaks are suitable hosts.

The prevalence of Giardia duodenalis (G. duodenalis) assemblages in yaks is poorly known. The present study examined 297 fecal samples from weaned yak, 4-7 months of age, from 3 different farms, in Tibetan Plateau Area (TPA) of the Qinghai Province in Western China. The prevalence of infection was determined by light and immunofluorescence microscopy, and nested-PCR. PCR was performed for the small subunit ribosomal RNA (SSU) amplified 16 positive for G. duodenalis products. The prevalence of Giardia species was 5.0% (15/297) on light microscopic analysis, 6.1% (18/297) on immunofluorescence test (IFT) and 5.4% (16/297) on nested-PCR. The overall prevalence with the three methods was 5.5%. Ten of the 16 PCR products have been successfully sequenced. Sequence results and phylogenetic analysis of the 18S rRNA sequence data using MEGA5.0 and DNAstar7.0 identified all samples of interest as G. duodenalis assemblage E. This study revealed for the first time the presence of G. duodenalis in yaks from the Qinghai province in China and confirmed that yak is a suitable host for Giardia parasites. The results provide useful information about G. duodenalis prevalence and the epidemiological significance of yak a suitable host to harbor Giardia infections.

RNA-binding protein HuR promotes growth of small intestinal mucosa by activating the Wnt signaling pathway.

Inhibition of growth of the intestinal epithelium, a rapidly self-renewing tissue, is commonly found in various critical disorders. The RNA-binding protein HuR is highly expressed in the gut mucosa and modulates the stability and translation of target mRNAs, but its exact biological function in the intestinal epithelium remains unclear. Here, we investigated the role of HuR in intestinal homeostasis using a genetic model and further defined its target mRNAs. Targeted deletion of HuR in intestinal epithelial cells caused significant mucosal atrophy in the small intestine, as indicated by decreased cell proliferation within the crypts and subsequent shrinkages of crypts and villi. In addition, the HuR-deficient intestinal epithelium also displayed decreased regenerative potential of crypt progenitors after exposure to irradiation. HuR deficiency decreased expression of the Wnt coreceptor LDL receptor-related protein 6 (LRP6) in the mucosal tissues. At the molecular level, HuR was found to bind the Lrp6 mRNA via its 3'-untranslated region and enhanced LRP6 expression by stabilizing Lrp6 mRNA and stimulating its translation. These results indicate that HuR is essential for normal mucosal growth in the small intestine by altering Wnt signals through up-regulation of LRP6 expression and highlight a novel role of HuR deficiency in the pathogenesis of intestinal mucosal atrophy under pathological conditions.

Activation of Wnt/beta-catenin signaling increases insulin sensitivity through a reciprocal regulation of Wnt10b and SREBP-1c in skeletal muscle cells.

BACKGROUND: Intramyocellular lipid accumulation is strongly related to insulin resistance in humans, and we have shown that high glucose concentration induced de novo lipogenesis and insulin resistance in murin muscle cells. Alterations in Wnt signaling impact the balance between myogenic and adipogenic programs in myoblasts, partly due to the decrease of Wnt10b protein. As recent studies point towards a role for Wnt signaling in the pathogenesis of type 2 diabetes, we hypothesized that activation of Wnt signaling could play a crucial role in muscle insulin sensitivity. METHODOLOGY/PRINCIPAL FINDINGS: Here we demonstrate that SREBP-1c and Wnt10b display inverse expression patterns during muscle ontogenesis and regeneration, as well as during satellite cells differentiation. The Wnt/beta-catenin pathway was reactivated in contracting myotubes using siRNA mediated SREBP-1 knockdown, Wnt10b over-expression or inhibition of GSK-3beta, whereas Wnt signaling was inhibited in myoblasts through silencing of Wnt10b. SREBP-1 knockdown was sufficient to induce Wnt10b protein expression in contracting myotubes and to activate the Wnt/beta-catenin pathway. Conversely, silencing Wnt10b in myoblasts induced SREBP-1c protein expression, suggesting a reciprocal regulation. Stimulation of the Wnt/beta-catenin pathway i) drastically decreased SREBP-1c protein and intramyocellular lipid deposition in myotubes; ii) increased basal glucose transport in both insulin-sensitive and insulin-resistant myotubes through a differential activation of Akt and AMPK pathways; iii) restored insulin sensitivity in insulin-resistant myotubes. CONCLUSIONS/SIGNIFICANCE: We conclude that activation of Wnt/beta-catenin signaling in skeletal muscle cells improved insulin sensitivity by i) decreasing intramyocellular lipid deposition through downregulation of SREBP-1c; ii) increasing insulin effects through a differential activation of the Akt/PKB and AMPK pathways; iii) inhibiting the MAPK pathway. A crosstalk between these pathways and Wnt/beta-catenin signaling in skeletal muscle opens the exciting possibility that organ-selective modulation of Wnt signaling might become an attractive therapeutic target in regenerative medicine and to treat obese and diabetic populations.