Vitronectin-derived bioactive peptide prevents spondyloarthritis by modulating Th17/Treg imbalance in mice with curdlan-induced spondyloarthritis

Purpose Spondyloarthritis (SpA) is a systemic inflammatory arthritis mediated mainly by interleukin (IL)-17. The vitronectin-derived bioactive peptide, VnP-16, exerts an anti-osteoporotic effect via β1 and αvβ3 integrin signaling. SpA is associated with an increased risk of osteoporosis, and we investigated the effect of VnP-16 in mice with SpA. Methods SpA was induced by curdlan in SKG ZAP-70W163C mice, which were treated with vehicle, celecoxib, VnP-16, or VnP-16+celecoxib. The clinical score, arthritis score, spondylitis score, and proinflammatory cytokine expression of the spine were evaluated by immunohistochemical staining. Type 17 helper T cell (Th17) and regulatory T cell (Treg) differentiation in the spleen was evaluated by flow cytometry and in the spine by confocal staining. Splenocyte expression of signal transducer and activator of transcription (STAT) 3 and pSTAT3 was evaluated by in vitro Western blotting. Results The clinical score was significantly reduced in the VnP16+celecoxib group. The arthritis and spondylitis scores were significantly lower in the VnP-16 and VnP16+celecoxib groups than the vehicle group. In the spine, the levels of IL-1β, IL-6, tumor necrosis factor-α, and IL-17 expression were reduced and Th17/Treg imbalance was regulated in the VnP-16 alone and VnP-16+celecoxib groups. Flow cytometry of splenocytes showed increased polarization of Tregs in the VnP-16+celecoxib group. In vitro, VnP-16 suppressed pSTAT3. Conclusions VnP-16 plus celecoxib prevented SpA progression in a mouse model by regulating the Th17/Treg imbalance and suppressing the expression of proinflammatory cytokines.

Protein Kinase CK2 Maintains Reciprocal Balance Between Th17 and Treg Cells in the Pathogenesis of UC

Background T helper 17 and regulatory T cells balance have crucial effects on the development of ulcerative colitis (UC). Currently, how to break this balance has not yet been found. Protein kinase CK2 is involved in the pathogenesis of immune-related disorders. However, its effects on the development of UC are obscure. Methods The level of CK2 in the colonic tissues of UC patients was quantified by quantitative real-time polymerase chain reaction (qRT-PCR) and immune-histochemistry. Peripheral blood CD4+ T cells were treated with CK2 inhibitor CX4945 or transfected with Csnk2-interfering lentivirus; the mRNA expression and protein levels of inflammatory cytokines were detected by qRT-PCR, enzyme-linked immunosorbent assay, and flow cytometry. Moreover, CX4945 was administered to trinitrobenzene sulfonic acid (TNBS)–induced colitis mice model for determining the function of CK2 on the regulation of intestinal inflammation. Results The CK2 level was markedly increased in inflamed mucosa of UC and highly expressed in CD4+ T cells. Blockade of CK2 by CX4945 inhibited Th17 but promoted regulatory T-cell (Treg) immune responses in CD4+ T cells from patients with UC. Moreover, CK2 blockade alleviated TNBS-induced colitis in mice. Inhibition of CK2 suppressed Th17 but promoted Treg differentiation by decreasing the phosphorylation level of signal transducer and activator of transcription (STAT) 3 and increasing the phosphorylation level of STAT5. The RNA-Seq and co-immunoprecipitation analysis further showed that CK2 could interact with Sirtuin 1 (SIRT1) and downregulate SIRT1 expression, which participated in Th17 inhibition but promoted Treg differentiation. Sirtuin 1 upregulation ameliorated TNBS-induced colitis, whereas SIRT1 blockade aggravated TNBS-induced colitis in mice. Conclusions CK2 have crucial effects on the development of UC by maintaining reciprocal balance between Th17 and Treg cells. Protein kinase CK2 blockade might be considered as a new therapeutic approach for UC treatment.

Yellow fever disease severity is driven by an acute cytokine storm modulated by an interplay between the human gut microbiome and the metabolome

Infection with Yellow Fever (YF) can lead to multiple outcomes ranging from death from total organ failure to clearance of viremia and survival. The mechanisms underlying these differences in clinical outcomes have yet to be defined. We had access to a cohort of YF infected subjects that showed these range of outcomes. An unbiased integrated OMICs approach was used to identify pathways and effector molecules that drive the severe disease and death as compared to resolution of infection. We used the MELD and SIC score as objective markers of disease severity. We show that a specific signature of upregulated innate pro-inflammatory cytokines significantly demarcates subjects with severe disease leading to death from subjects who clear virus. Pathogen sequencing showed heightened levels of proteolytic bacteria at the i.e Actinobacteria and these were correlated to lower levels of tryptophan and tyrosine amino acids measured by untargeted metabolomics. These two features were significantly associated to MELD scores synonymous of milder disease. Propionate a bacterial metabolite that triggers Treg differentiation that can as well limit the hyperimmune activation associated to severe outcome was also associated to improved outcome. Our results suggest a model whereby proteolytic bacteria limit the availability of the aromatic amino acid pool available for cytokine production thereby preventing the induction of the cytokine storm that is associated to severe disease and death.

Ursodeoxycholic acid breaks antitumor immunosuppression by inducing CHIP-mediated TGF-β degradation

Blocking TGF-β signaling is critical to enhance antitumor immunity. However, there is still no effective TGF-β signaling inhibitors in clinic. Here, we show that clinical medicine ursodeoxycholic acid (UDCA) phosphorylates TGF-β at T282 site via TGR5-cAMP-PKA axis, leading to the increased binding of TGF-β and CHIP. Then, CHIP ubiquitinates TGF-β at K315 site, initiating p62-dependent autophagy sorting and subsequent TGF-β degradation. By degrading TGF-β, UDCA greatly enhances antitumor immunity through restraining Treg differentiation and activation in tumor-bearing mice. In addition, UDCA synergizes with anti-PD-1 to induce stronger antitumor immunity and tumor-specific immune memory in tumor-bearing mice. Notably, UDCA also reduces TGF-β and Tregs in peripheral blood of healthy volunteers and tumor patients. Therapy combining anti-PD-1 or anti-PD-L1 with UDCA has much better efficacy in tumor patients. Thus, our results uncover a novel mechanism for TGF-β signaling regulation and reveal UDCA as a ready-made TGF-β signaling inhibitor in enhancing antitumor immunity.

Spermidine dampens inflammation by directly inhibiting Th17 cytokine production through a PRDX1 associated antioxidant pathway

The activation of IL-17 signaling has been linked to the pathogenesis of many chronic, inflammatory lung diseases including Cystic Fibrosis (CF). Through unbiased single-cell RNAseq screening, we found that IL-17+ T cells highly express Srm and Smox, which encode two key enzymes for spermidine synthesis. Spermidine has been shown to reduce inflammation by regulating macrophage activation and balancing Th17/Treg differentiation, but its direct effects on Th17 cytokine production has not been carefully investigated. Here, using already differentiated Th17 cells from cultured mouse splenocytes, we found that exogenous spermidine directly inhibits IL-1β/IL-23 induced IL-17 production. Blockade of endogenous spermidine synthesis enhanced IL-17 production above native levels, further supporting that spermidine is a direct regulator of cytokine secretion independent of differentiation. In vivo, spermidine alleviates lung inflammation in both PA infection and LPS induced acute lung injury models. Further RNA-seq analysis suggests spermidine suppression of Th17 cytokine production is mediated through its PRDX1 dependent antioxidant activity. Our data establishes that spermidine is a direct regulator of Type-17 T cell cytokine production and has potent anti-inflammatory effects against lung inflammation.

Contribution of IL-38 in Lung Immunity During Pseudomonas Aeruginosa-Induced Pneumonia

Objective: Interleukin-38 (IL-38), a new type of cytokine, is involved in processes such as tissue repair, inflammatory response, and immune response. However, its function in pneumonia caused by Pseudomonas aeruginosa is still unclear.Methods: In this study, we detected circulating IL-38 in adults affected by pneumonia caused by P. aeruginosa. The P. aeruginosa-induced pneumonia WT murine model was adopted to evaluate the effect of IL-38 on Treg differentiation, cell apoptosis, survival, tissue damage, inflammation, and bacterial removal.Results: IL-38 is insufficiently secreted in patients who died of P.A. pneumonia.Recombinant IL-38 improved survival, whereas anti-IL-38 antibody reduced survival in the experimental pneumonia murine model. IL-38 exposure reduced the inflammatory response, as suggested by the lung injury, and reduced cytokine levels (IL-1β, IL-6, IL-17A, TNF-α, and CXCL-1, but not IL-10). It also increased bacterial clearance and reduced cell apoptosis in the lungs. Furthermore, IL-38 was shown to reduce TBK1 expression in vitro when naïve CD4+ T lymphocytes were differentiated to Tregs and played a protective role in P.A. pneumonia.Conclusions: To summarize, the above findings provide additional insights into the mechanism of IL-38 in the treatment of P.A. pneumonia.

Loss of 15-lipoxygenase disrupts Treg differentiation altering their pro-resolving functions

Regulatory T-cells (Tregs) are central in the maintenance of homeostasis and resolution of inflammation. However, the mechanisms that govern their differentiation and function are not completely understood. Herein, we demonstrate a central role for the lipid mediator biosynthetic enzyme 15-lipoxygenase (ALOX15) in regulating key aspects of Treg biology. Pharmacological inhibition or genetic deletion of ALOX15 in Tregs decreased FOXP3 expression, altered Treg transcriptional profile and shifted their metabolism. This was linked with an impaired ability of Alox15-deficient cells to exert their pro-resolving actions, including a decrease in their ability to upregulate macrophage efferocytosis and a downregulation of interferon gamma expression in Th1 cells. Incubation of Tregs with the ALOX15-derived specilized pro-resolving mediators (SPM)s Resolvin (Rv)D3 and RvD5n-3 DPA rescued FOXP3 expression in cells where ALOX15 activity was inhibited. In vivo, deletion of Alox15 led to increased vascular lipid load and expansion of Th1 cells in mice fed western diet, a phenomenon that was reversed when Alox15-deficient mice were reconstituted with wild type Tregs. Taken together these findings demonstrate a central role of pro-resolving lipid mediators in governing the differentiation of naive T-cells to Tregs.

Bacteroides fragilis controls intestinal inflammation through promoting Treg differentiation via TGF-β/Smad3 signaling pathway

Alteration of intestinal flora is usually associated with various gastrointestinal diseases.Microbial homeostasis can enhance host immune tolerance and regulate intestinal immune balance.Our previous studies have found that the peptidoglycan framework of Lactococcus lactis(L.lactis),gram positive enhancer matrix particles (GEM),improved the intestinal flora diversity and significantly increased the relative abundance of Bacteroidetes in colitic mice.Of note,Bacteroides fragilis(B.fragilis) can alleviate inflammation by promoting the expressions of intestinal regulatory T cells (Tregs) and anti-inflammatory cytokines.However, mechanism of B.fragilis regulating intestinal immunity remains unclear,thus we here seek to explore the effects of B.fragilis and its mechanism by DSS-induced experimental colitis.Results show that B.fragilis contributes to the restoration of gut microbiota composition and an increase in short-chain fatty acids(SCFAs) production of mice with colitis.The treatment mediates the differentiation of naive CD4+ T cells into Tregs probably through TGF-β activated by SCFAs,and TGF-β/Smad3 signaling is indispensable for both Treg expansion and IL-10 expression.The study demonstrates the immune pathways by which B.fragilis controls the inflammatory process and it may be an effective therapeutic option for intestinal diseases.