Project description:Regulation of hippocampal neurogenesis is poorly understood, but appears to contribute to mood and cognition. Ethanol and neuroinflammation are known to reduce neurogenesis. We have found that ethanol induces neuroinflammation supporting the hypothesis that ethanol induction of neuroinflammation contributes to ethanol inhibition of neurogenesis. To identify the key proinflammatory molecule that may be responsible for ethanol-impaired neurogenesis we used an ex vivo model of organotypic hippocampal-entorhinal cortex brain slice cultures. Here, we demonstrated a key role of proinflammatory cytokine IL-1β signaling in mediating ethanol inhibition of neurogenesis. Ethanol inhibition of neurogenesis was reversed by neutralizing antibody to IL-1β or blockade of the IL-1β receptor with antagonist IL-1RIa. Ethanol-impaired neurogenesis is associated with strong induction of IL-1β and inflammasome proteins NALP1 and NALP3 in both neurons and astrocytes. Blockade of IL-1β synthesis with inflammasome inhibitors Parthenolide and Bay11708 significantly reversed ethanol inhibited neurogenesis. Furthermore, we also found that IL-1β and inflammasome proteins NALP1 and NALP3 are increased in hippocampal neurons and astrocytes in postmortem alcoholic human brain. Together, these novel findings demonstrate that targeting inflammasome-IL-1β signaling can normalize ethanol-impaired hippocampal neurogenesis, which may have therapeutic implications for treatment of cognitive impairment associated with hippocampal dysfunction in alcoholics.
Project description:Diabetes mellitus (DM) is an independent risk factor for atrial fibrillation (AF). The mechanisms underlying DM-associated AF are unclear. AF and DM are both related to inflammation. We investigated whether DM-associated inflammation contributed to AF risk. Mice were fed with high-fat diet to induce type II DM and were subjected to IL-1β antibodies, macrophage depletion by clodronate liposomes, a mitochondrial antioxidant (mitoTEMPO), or a cardiac ryanodine receptor 2 (RyR2) stabilizer (S107). All tests were performed at 36-38 weeks of age. DM mice presented with increased AF inducibility, enhanced mitochondrial reactive oxygen species (mitoROS) generation, and activated innate immunity in the atria, as evidenced by enhanced monocyte chemoattractant protein-1 (MCP-1) expression, macrophage infiltration, and IL-1β levels. Signs of aberrant RyR2 Ca2+ leak were observed in the atria of DM mice. IL-1β neutralization, macrophage depletion, and exposure to mitoTEMPO and S107 significantly ameliorated the AF vulnerability in DM mice. Atrial overexpression of MCP-1 increased AF occurrence in normal mice through the same mechanistic signaling cascade as observed in DM mice. In conclusion, macrophage-mediated IL-1β contributed to DM-associated AF risk through mitoROS modulation of RyR2 Ca2+ leak.
Project description:Candida tropicalis-a prevalent gut commensal fungus in healthy individuals - contributes to intestinal health and disease. However, how commensal C. tropicalis influences intestinal homeostasis and barrier function is poorly understood. Here, we demonstrated that the reference strain of C. tropicalis (MYA-3404) ameliorated intestinal inflammation in murine models of chemically induced colitis and bacterial infection. Intestinal colonization of C. tropicalis robustly upregulated the expression of IL-17A and IL-22 to increase barrier function and promote proliferation of intestinal epithelial cells in the mouse colon. Metabolomics analysis of fecal samples from mice colonized with C. tropicalis revealed alterations in vitamin B3 metabolism, promoting conversion of nicotinamide to nicotinic acid. Although nicotinamide worsened colitis, treatment with nicotinic acid alleviated disease symptoms and enhanced epithelial proliferation and Th17 cell differentiation. Oral gavage of C. tropicalis mitigated nicotinamide-induced intestinal dysfunction in experimental colitis. Blockade of nicotinic acid production with nicotinamidase inhibitors lowered the protective effects against colitis in mice treated with C. tropicalis. Notably, a clinical C. tropicalis strain isolated from patients with candidemia lacked the protective effects against murine colitis observed with the reference strain. Together, our results highlight a novel role for C. tropicalis in resolving intestinal inflammation through the modulation of vitamin B3 metabolism.
Project description:Caspase 8, the initiator caspase for death receptor-induced apoptosis, functions as a negative regulator of receptor interacting protein kinase 3 (RIPK3), an essential factor for TNF-, TLR3-, and TLR4-induced necroptosis. In certain situations, caspase 8 can also participate in pro-IL-1β processing. However, the biochemical complex that mediates caspase 8-mediated processing is not defined. In this study, we show that RIPK3 is crucial for caspase 1- and caspase 8-mediated pro-IL-1β and pro-IL-18 processing in bone marrow-derived dendritic cells (BMDCs) in response to LPS stimulation. Caspase 8-mediated pro-IL-1β processing requires intact RIPK1, RIPK3, TRIF, and FADD. In response to LPS, a complex that contains RIPK1, RIPK3, FADD, and caspase 8 is formed. Surprisingly, RIPK3-specific kinase inhibitors strongly enhanced caspase 8 activation and pro-IL-1β processing in LPS-stimulated BMDCs. However, studies in BMDCs expressing the kinase-inactive RIPK3-K51A mutant or RIPK1-K45A mutant showed that the kinase activity of neither RIPK1 nor RIPK3 is required for LPS-induced caspase 8 activation and IL-1β secretion. Hence, RIPK3 is an unexpected positive regulator of caspase 8 activity that promotes IL-1β maturation in BMDCs.
Project description:Myeloid-derived suppressor cells (MDSCs) are a group of innate immune cells that regulates both innate and adaptive immune responses. In recent years, MDSCs were shown to play an important negative regulatory role in transplant immunology even upstream of regulatory T cells. In certain cases, MDSCs are closely involved in transplantation immune tolerance induction and maintenance. It is known that some immunosuppressant drugs negatively regulate MDSCs but others have positive effects on MDSCs in different transplant cases. We herein summarized our recent insights into the regulatory roles of MDSCs in transplantation specially focusing on the effects of immunosuppressive drugs on MDSCs and their mechanisms of action. Studies on the effects of immunosuppressive drugs on MDSCs will significantly expand our understanding of immunosuppressive drugs on immune regulatory cells in transplantation and offer new insights into transplant tolerance. We hope to emphasize our concern for the negative effects of immunosuppressive agents on MDSCs, which may potentially attenuate the immune tolerance induction in transplanted recipients.
Project description:In infants intolerant of enteral feeding because of intestinal disease, parenteral nutrition may be associated with cholestasis, which can progress to end-stage liver disease. Here we show the function of hepatic macrophages and phytosterols in parenteral nutrition-associated cholestasis (PNAC) pathogenesis using a mouse model that recapitulates the human pathophysiology and combines intestinal injury with parenteral nutrition. We combine genetic, molecular, and pharmacological approaches to identify an essential function of hepatic macrophages and IL-1β in PNAC. Pharmacological antagonism of IL-1 signaling or genetic deficiency in CCR2, caspase-1 and caspase-11, or IL-1 receptor (which binds both IL-1α and IL-1β) prevents PNAC in mice. IL-1β increases hepatocyte NF-κB signaling, which interferes with farnesoid X receptor and liver X receptor bonding to respective promoters of canalicular bile and sterol transporter genes (Abcc2, Abcb11, and Abcg5/8), resulting in transcriptional suppression and subsequent cholestasis. Thus, hepatic macrophages, IL-1β, or NF-κB may be targets for restoring bile and sterol transport to treat PNAC.
Project description:Gasdermin D (GSDMD) induces pyroptosis via the pore-forming activity of its N-terminal domain, cleaved by activated caspases associated with the release of IL-1β. Here, we report a nonpyroptotic role of full-length GSDMD in guiding the release of IL-1β-containing small extracellular vesicles (sEVs) from intestinal epithelial cells (IECs). In response to caspase-8 inflammasome activation, GSDMD, chaperoned by Cdc37/Hsp90, recruits the E3 ligase, NEDD4, to catalyze polyubiquitination of pro-IL-1β, serving as a signal for cargo loading into secretory vesicles. GSDMD and IL-1β colocalize with the exosome markers CD63 and ALIX intracellularly, and GSDMD and NEDD4 are required for release of CD63+ sEVs containing IL-1β, GSDMD, NEDD4, and caspase-8. Importantly, increased expression of epithelial-derived GSDMD is observed both in patients with inflammatory bowel disease (IBD) and those with experimental colitis. While GSDMD-dependent release of IL-1β-containing sEVs is detected in cultured colonic explants from colitic mice, GSDMD deficiency substantially attenuates disease severity, implicating GSDMD-mediated release of IL-1β sEVs in the pathogenesis of intestinal inflammation, such as that observed in IBD.
Project description:Colorectal cancer (CRC) development and progression is associated with chronic inflammation. We have identified the MAPK-activated protein kinase 2 (MK2) pathway as a primary mediator of inflammation in CRC. MK2 signaling promotes production of proinflammatory cytokines IL-1β, IL-6 and TNF-α. These cytokines have been implicated in tumor growth, invasion and metastasis. For the first time, we investigate whether MK2 inhibition can improve outcome in two mouse models of CRC. In our azoxymethane/dextran sodium sulfate (AOM/DSS) model of colitis-associated CRC, MK2 inhibitor treatment eliminated murine tumor development. Using the implanted, syngeneic murine CRC cell line CT26, we observe significant tumor volume reduction following MK2 inhibition. Tumor cells treated with MK2 inhibitors produced 80% less IL-1β, IL-6 and TNF-α and demonstrated decreased invasion. Replenishment of downstream proinflammatory MK2-mediated cytokines (IL-1β, IL-6 and TNF-α) to tumors led to restoration of tumor proliferation and rapid tumor regrowth. These results demonstrate the importance of MK2 in driving proinflammatory cytokine production, its relevance to in vivo tumor proliferation and invasion. Inhibition of MK2 may represent an attractive therapeutic target to suppress tumor growth and progression in patients.
Project description:Osteoarthritis (OA) is a common chronic degenerative condition in the elderly, in which inflammation plays a key role in disease pathology. Lycopene (Lye), a member of the carotenoid family, has been reported to have anti-inflammatory effects. The purpose of this study was to investigate the effect of Lye on the inflammation of chondrocytes and the mouse OA model. Chondrocytes were treated with interleukin (IL)-1β, and the mouse OA model was induced by the surgical destabilization of the medial meniscus (DMM). The results showed that Lye could inhibit the expression of inflammatory factors and alleviate the degradation of extracellular matrix (ECM). Additionally, Lye could activate the Nrf2/HO-1 pathway and reverse the activations of NF-κB and STAT3 signal pathway induced by IL-1β, suggesting that its anti-inflammatory effect may be mediated via these pathways. The animal experiments showed that Lye could decrease the Osteoarthritis Research Society International (OARSI) scores of the knee, indicating that it could inhibit the occurrence and development of OA in mouse. Overall, our results indicated that Lye might be used as a novel drug for OA treatment.
Project description:Under the condition of lipopolysaccharide (LPS)/interferon (IFN)-γ activation, macrophage metabolism is converted from oxidative phosphorylation to glycolysis. In the present work, we analysed whether glycolysis could affect interleukin (IL)-1β expression through altering histone acetylation levels in mouse bone marrow-derived macrophages. Immunocytochemistry and Western blot analysis are used to characterize histone acetylation in macrophages stimulated by LPS/IFN-γ. Real-time polymerase chain reaction and enzyme-linked immunosorbent assay were used to determine IL-1β production. The metabolism of macrophages was monitored in real-time by the Seahorse test. Our results showed that glycolytic metabolism could enhance histone acetylation and promote IL-1β production in LPS/IFN-γ-activated macrophages. Moreover, increased production of IL-1β by glycolysis was mediated through enhanced H3K9 acetylation. Importantly, it was found that a high dose of histone deacetylase inhibitor could also significantly increase the expression of IL-1β in the absence of glycolytic metabolism. In conclusion, this study demonstrates that glycolytic metabolism could regulate IL-1β expression by increasing histone acetylation levels in LPS/IFN-γ-stimulated macrophages.