Purine metabolites promote ectopic new bone formation in ankylosing spondylitis.

Ankylosing spondylitis (AS) is a chronic inflammatory rheumatic disease that mainly affects the axial skeleton, whose typical features are inflammatory back pain, bone structural damage and pathological new bone formation. The pathology of ectopic new bone formation is still little known. In this study, we found increased purine metabolites in plasma of patients with AS. Similarly, metabolome analysis indicated increased purine metabolites in both serum of CD4-Cre; Ptpn11fl/fl and SHP2-deficient chondrocytes. SHP2-deficient chondrocytes promoted the growth of wild type chondrocytes and differentiation of osteoblasts in CD4-Cre; Ptpn11fl/fl mice, which spontaneously developed AS-like bone disease. Purine metabolites, along with PTHrP derived from SHP2-deficient chondrocytes, accelerated the growth of chondrocytes and ectopic new bone formation through PKA/CREB signaling. Moreover, Suramin, a purinergic receptor antagonist, suppressed pathological new bone formation in AS-like bone disease. Overall, these results highlight the potential role of targeting purinergic signaling in retarding ectopic new bone formation in AS.

Case report: A STAT1 gain-of-function mutation causes a syndrome of combined immunodeficiency, autoimmunity and pure red cell aplasia.

Inherited autosomal dominant gain-of-function (GOF) mutations of signal transducer and activator of transcription 1 (STAT1) cause a wide range of symptoms affecting multiple systems, including chronic mucocutaneous candidiasis (CMC), infections, and autoimmune disorders. We describe a rare case of STAT1 mutation with recurrent CMC, lung infections, and anemia. According to the whole-exome sequencing (WES), the patient was genetically mutated in STAT1 GOF (c.854A>G, p.Q285R), and bone marrow biopsy suggested pure red cell aplasia (PRCA). As a functional verification, STAT1 levels and phosphorylation (p-STAT1) of peripheral blood mononuclear cells (PBMCs) following IFN-γ stimulation in STAT1 GOF patient was higher than in the healthy control. Combination therapy of blood transfusion, antimicrobials, intravenous immunoglobulin, methylprednisolone, and the Janus Kinase (JAK) specific inhibitor ruxolitinib was used during treatment of patients. The patient also received a hematopoietic stem cell transplant (HSCT) to help with infections and anemia. This is the first reported case of STAT1 GOF disease complicated with PRCA. This complication might be attributed to immune disorders caused by STAT1 GOF. Furthermore, ruxolitinib may be a viable therapeutic option before HSCT to improve disease management.

Allosteric inhibition of SHP2 uncovers aberrant TLR7 trafficking in aggravating psoriasis.

Psoriasis is a complex chronic inflammatory skin disease with unclear molecular mechanisms. We found that the Src homology-2 domain-containing protein tyrosine phosphatase-2 (SHP2) was highly expressed in both psoriatic patients and imiquimod (IMQ)-induced psoriasis-like mice. Also, the SHP2 allosteric inhibitor SHP099 reduced pro-inflammatory cytokine expression in PBMCs taken from psoriatic patients. Consistently, SHP099 significantly ameliorated IMQ-triggered skin inflammation in mice. Single-cell RNA sequencing of murine skin demonstrated that SHP2 inhibition impaired skin inflammation in myeloid cells, especially macrophages. Furthermore, IMQ-induced psoriasis-like skin inflammation was significantly alleviated in myeloid cells (monocytes, mature macrophages, and granulocytes)-but not dendritic cells conditional SHP2 knockout mice. Mechanistically, SHP2 promoted the trafficking of toll-like receptor 7 (TLR7) from the Golgi to the endosome in macrophages by dephosphorylating TLR7 at Tyr1024, boosting the ubiquitination of TLR7 and NF-κB-mediated skin inflammation. Importantly, Tlr7 point-mutant knock-in mice showed an attenuated psoriasis-like phenotype compared to wild-type littermates following IMQ treatment. Collectively, our findings identify SHP2 as a novel regulator of psoriasis and suggest that SHP2 inhibition may be a promising therapeutic approach for psoriatic patients.

Targeting chondrocytes for arresting bony fusion in ankylosing spondylitis.

Bony fusion caused by pathological new bone formation manifests the clinical feature of ankylosing spondylitis (AS). However, the underlying mechanism remains elusive. Here we discovered spontaneous kyphosis, arthritis and bony fusion in mature CD4-Cre;Ptpn11f/f mice, which present the pathophysiological features of AS. A population of CD4-Cre-expressing proliferating chondrocytes was SHP2 deficient, which could differentiate into pre-hypertrophic and hypertrophic chondrocytes. Functionally, SHP2 deficiency in chondrocytes impeded the fusion of epiphyseal plate and promoted chondrogenesis in joint cavity and enthesis. Mechanistically, aberrant chondrocytes promoted ectopic new bone formation through BMP6/pSmad1/5 signaling. It is worth emphasizing that such pathological thickness of growth plates was evident in adolescent humans with enthesitis-related arthritis, which could progress to AS in adulthood. Targeting dysfunctional chondrogenesis with Smo inhibitor sonidegib significantly alleviated the AS-like bone disease in mice. These findings suggest that blockade of chondrogenesis by sonidegib would be a drug repurposing strategy for AS treatment.

Enhanced Copper-Temozolomide Interactions by Protein for Chemotherapy against Glioblastoma Multiforme.

Current treatment of recurrent glioblastoma multiforme (GBM) demands dose-intense temozolomide (TMZ), a prodrug of 5-(3-methyltriazen-1-yl) imidazole-4-carboxamide (MTIC), based on the spontaneous hydrolysis of TMZ at basic pH. However, how to control the activity of MTIC remains unknown, which poses a particular challenge to search a reliable MTIC receptor. We reported that copper, for the first time, is found to recognize and bind MTIC in the process of TMZ degradation, which means copper can play an important role in enhancing the bioavailability of MTIC derived from TMZ. Using apoferritin as a model copper-bound protein, we studied the copper-TMZ interaction in protein and observed efficient MTIC immobilization with high binding efficiency (up to 92.9% based on original TMZ) and capacity (up to 185 MTIC moieties per protein). The system was stable against both alkaline and acidic pH and could be activated by glutathione to liberate MTIC, which paves a way to deliver a DNA-alkylating agent for both TMZ-sensitive and TMZ-resistant GBM chemotherapy. Our study provides a new insight for understanding the potential relationship between the special GBM microenvironment (specific copper accumulation) and the therapeutic effect of TMZ.

cis-Khellactone Inhibited the Proinflammatory Macrophages via Promoting Autophagy to Ameliorate Imiquimod-Induced Psoriasis.

Psoriasis is a chronic inflammatory skin disease with unresolved pathogenesis. Studies on the pathogenesis of psoriasis have been extensively carried out, but treatments are still not satisfactory. In this study, we found improvement after treatment with cis-khellactone, a small molecular natural product, in imiquimod-challenged C57BL/6 mice. cis-Khellactone clearly reduced the level of cytokines in psoriatic skin, including IL-23, TNF-α, IL-1ß, and IL-6, while limiting the inhibition of IL-17A, which is produced by T helper type 17 cells. cis-Khellactone treatment specifically decreased dermal macrophage infiltration in psoriatic skin but not in neutrophils or T cells. Additionally, compared with the control group, cis-khellactone significantly decreased the activation of NF-κB p65 in these infiltrated macrophages. Further study showed that cis-khellactone suppressed proinflammatory phenotypic macrophages by promoting autophagy. Blocking autophagy by silencing Beclin1 or Atg7 abrogated the effect of cis-khellactone on macrophages. The autophagy-dependent improvement in psoriasis from cis-khellactone treatment was further manifested by its limited effects on skin lesions in chloroquine-treated mice. Moreover, cis-khellactone showed lower toxicity levels than methotrexate in macrophages and primary hepatocytes. Taken together, cis-khellactone selectively modulated macrophage function and phenotype by inducing autophagy to ameliorate imiquimod-induced psoriasis in mice. Our research provides an effective strategy for the treatment of psoriasis.

Targeting Peroxiredoxin 1 by a Curcumin Analogue, AI-44, Inhibits NLRP3 Inflammasome Activation and Attenuates Lipopolysaccharide-Induced Sepsis in Mice.

Aberrant activation of the NLRP3 inflammasome contributes to the onset and progression of various inflammatory diseases, making it a highly desirable drug target. In this study, we screened a series of small compounds with anti-inflammatory activities and identified a novel NLRP3 inflammasome inhibitor, AI-44, a curcumin analogue that selectively inhibited signal 2 but not signal 1 of NLRP3 inflammasome activation. We demonstrated that AI-44 bound to peroxiredoxin 1 (PRDX1) and promoted the interaction of PRDX1 with pro-Caspase-1 (CASP1), which led to the suppression of association of pro-CASP1 and ASC. Consequently, the assembly of the NLRP3 inflammasome was interrupted, and the activation of CASP1 was inhibited. Knockdown of PRDX1 significantly abrogated the inhibitory effect of AI-44 on the NLRP3 inflammasome. Importantly, AI-44 alleviated LPS-induced endotoxemia in mice via suppressing NLRP3 inflammasome activation. Taken together, our work highlighted PRDX1 as a negative regulator of NLRP3 inflammasome activation and suggested AI-44 as a promising candidate compound for the treatment of sepsis or other NLRP3 inflammasome-driven diseases.

Protein Nanocage-Based Photo-Controlled Nitric Oxide Releasing Platform.

A photoactive NO releasing system was constructed by incorporation of NO-bound Fe-S clusters into horse spleen apoferritin cavities with high loading efficacy. The composites retained intact core-shell structure and indicated advantages such as enhanced stability, reduced cytotoxicity, efficient cellular uptake, and photocontrolled NO releasing property.

A fumigaclavine C isostere alleviates Th1-mediated experimental colitis via competing with IFN-γ for binding to IFN-γ receptor 1.

Interferon gamma (IFN-γ) signaling in T cells plays an important role in developing T helper 1 (Th1)-mediated inflammation. Selective regulation of IFN-γ signaling is an attractive strategy for treating Th1-mediated immune diseases. In this study, we aimed to explore possible means of targeting IFN-γ signaling by using small molecule compound. A synthetic small molecule FC9 was identified as it selectively inhibited IFN-γ signaling in T cells without suppressing interleukin 4 (IL-4) signaling. Furthermore, FC9 inhibited IFN-γ-induced Janus kinase 2 (JAK2) activation via competing with IFN-γ for binding to IFN-γ receptor 1 (IFN-γ R1). Interestingly, we found that FC9 bound to IFN-γ R1 and selectively suppressed Th1 but not Th2 immune response in T cells, resulting in an improvement in 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in mice. In conclusion, FC9-induced competitive blockade of IFN-γ R1 for selective inhibition of IFN-γ signaling, demonstrated a novel mean of targeting IFN-γ signaling. These findings could lead to increased options for the treatment of Crohn's disease and other Th1-mediated inflammatory diseases.

CUG-binding protein 1 regulates HSC activation and liver fibrogenesis.

Excessive activation of hepatic stellate cells (HSCs) is a key step in liver fibrogenesis. Here we report that CUG-binding protein 1 (CUGBP1) expression is elevated in HSCs and positively correlates with liver fibrosis severity in human liver biopsies. Transforming growth factor-beta (TGF-ß) selectively increases CUGBP1 expression in cultured HSCs in a p38 mitogen-activated protein kinase (MAPK)-dependent manner. Knockdown of CUGBP1 inhibits alpha smooth muscle actin (α-SMA) expression and promotes interferon gamma (IFN-γ) production in HSCs in vitro. We further show that CUGBP1 specifically binds to the 3' untranslated region (UTR) of human IFN-γ mRNA and promotes its decay. In mice, knockdown of CUGBP1 alleviates, whereas its overexpression exacerbates, bile duct ligation (BDL)-induced hepatic fibrosis. Therefore, CUGBP1-mediated IFN-γ mRNA decay is a key event for profibrotic TGF-ß-dependent activation of HSCs, and inhibiting CUGBP1 to promote IFN-γ signalling in activated HSCs could be a novel strategy to treat liver fibrosis.

Andrographolide alleviates imiquimod-induced psoriasis in mice via inducing autophagic proteolysis of MyD88.

Psoriasis is a chronic inflammatory skin disease with excessive activation of toll-like receptors (TLRs), which play important roles in developing psoriasis. Targeting TLR signaling remains a challenge for treating psoriasis. Here, we found that andrographolide (Andro), a small-molecule natural product, alleviated imiquimod- but not interleukin 23 (IL-23)-induced psoriasis in mice with reducing expressions of IL-23 and IL-1ß in the skin. The improvement in imiquimod-induced psoriasis by Andro was not observed in microtubule-associated protein 1 light chain 3 beta (MAP1LC3B) knockout mice. Furthermore, Andro inhibited mRNA expressions of IL-23, IL-6 and IL-1ß but not CD80 and CD86 in bone-marrow derived dendritic cells (BMDCs) treated with lipopolysaccharide (LPS) in a MAP1LC3B-dependent manner. In addition, Andro inhibited imiquimod-induced mRNA expressions of IL-23, IL-6, IL-1ß, CD80 and CD86 in BMDCs from mice. Interestingly, Andro induced a degradation of myeloid differentiation factor 88 (MyD88) and blocked the recruitment of TNF receptor-associated factor 6 (TRAF6) to MyD88 upon LPS stimulation in BMDCs from mice. Blockade of autophagic proteolysis using NH4Cl or MAP1LC3B(-/-) BMDCs abolished the Andro-induced MyD88 degradation. In conclusion, Andro controls activation of MyD88-dependent cytokines and alleviates psoriasis in mice via inducing autophagic proteolysis of MyD88, which could be a novel strategy to treat psoriasis.

Fumigaclavine C ameliorates dextran sulfate sodium-induced murine experimental colitis via NLRP3 inflammasome inhibition.

In the present study, the effect of Fumigaclavine C, a fungal metabolite, on murine experimental colitis induced by dextran sulfate sodium (DSS) and its possible mechanism were examined in vivo and vitro. Oral administration of Fumigaclavine C dose-dependently attenuated the loss of body weight and shortening of colon length induced by DSS. The disease activity index, histopathologic scores of musco was also significantly reduced by Fumigaclavine C treatment. Protein and mRNA levels of DSS-induced pro-inflammatory cytokines in colon, including TNF-α, IL-1ß and IL-17A, were markedly suppressed by Fumigaclavine C. At the same time, decreased activation of caspase-1 in peritoneal macrophages was detected in Fumigaclavine C -treated mice which suggested that the NLRP3 inflammasome activation was suppressed. Furthermore, in the LPS plus ATP cell model, we found that Fumigaclavine C dose-dependent inhibited IL-1ß release and caspase-1 activation. Taken together, our results demonstrate the ability of Fumigaclavine C to inhibit NLRP3 inflammasome activation and give some evidence for its potential use in the treatment of inflammatory bowel diseases.

Epigallocatechin-3-gallate sensitizes IFN-γ-stimulated CD4+ T cells to apoptosis via alternative activation of STAT1.

Epigallocatechin-3-gallate (EGCG) exerts anti-inflammatory properties on immune cells and binds to CD4 molecules. However, the effects of EGCG on CD4(+) T cells remain largely unknown. Here, we found that EGCG enhanced IFN-γ-induced signal transducer and activator of transcription 1 (STAT1) activation in primary CD4(+) T cells from C57BL/6 mice and in a human leukemic CD4(+) T-cell line of Hut 78 cells, while it inhibited the classical pathway of IFN-γ signaling including activating phosphorylations of Janus kinase (JAK) 1, JAK2 and STAT3, forming interferon-γ activated sequence (GAS)-binding STAT1 homodimers, and producing pro-inflammatory chemokine (C-X-C motif) ligand 9 (CXCL9). CD4 blockade did not suppress the increase in IFN-γ-induced STAT1 activation in CD4(+) T cells by EGCG. Furthermore, activation of Src kinase was also triggered by IFN-γ plus EGCG in both Hut 78 and primary CD4(+) T cells. Interestingly, EGCG promoted apoptosis of CD4(+) T cells treated with IFN-γ. The increases in STAT1 activation and apoptosis induced by EGCG in IFN-γ-activated CD4(+) T cells were almost completely abolished by a selective Src family kinase inhibitor, SU6656. Moreover, EGCG alleviates CD4(+) CD45RB(hi) CD25(-) T cell transfer induced colitis with less accumulation of CD4(+) T cells in the colon. In conclusion, the present study reports an alternative activation of STAT1 via Src by EGCG in IFN-γ-activated CD4(+) T cells, which promotes the apoptosis of IFN-γ-activated CD4(+) T cells and contributes to the improvement of T cell-mediated colitis. Our findings suggest a novel role of EGCG in regulating IFN-γ signaling and controlling inflammation.