CD1d1 intrinsic signaling in macrophages controls NLRP3 inflammasome expression during inflammation

In vivo and in situ monitoring of doxorubicin pharmacokinetics with an implantable bioresorbable optical sensor

Cancer treatment, particularly chemotherapy, requires balancing efficacy and toxicity. Although traditional monitoring methods can lead to suboptimal outcomes, emerging implantable chemical sensors can complement them by providing precise, real-time drug monitoring at tumor sites, although the technology remains in its early stages. Here, we introduce an ultrathin, bioresorbable implantable biosensor for real-time doxorubicin monitoring in vivo with high spatiotemporal resolution. The sensor amplifies the drug's fluorescence, enabling successful tracking of doxorubicin through the skin in live mice following intravenous injection. When paired with a reusable electronic patch, the biosensor facilitates seamless data collection and wireless transmission. A 3-month biocompatibility study, including systemic toxicity assessments, histological and blood analyses, confirms complete biodegradation with no observed toxicity. By directly measuring chemotherapeutic drug levels in tissues over time, our sensor enhances traditional monitoring methods, enabling clinicians to optimize dosing during cancer treatment and reduce the risk of locoregional recurrence following tumor removal.

Macrophage-targeting nano-formulated bicalutamide alleviates colitis by inducing MAP3K1-mediated degradation of NLRP3

The excessive activation of the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) in macrophages has been recognized as a critical factor in the exacerbation of severe inflammatory bowel disease (IBD). Consequently, the modulation of macrophage NLRP3 activity may serve as an effective strategy for mitigating IBD. Our study has indicated that bicalutamide, a clinically administered agent, has the capacity to reduce inflammation by promoting the degradation of NLRP3 in a macrophage-specific manner. However, the therapeutic efficacy of bicalutamide in treating colitis has remained limited. In an effort to enhance the precision of NLRP3 regulation, a nano-bicalutamide system targeting macrophages has been developed, which has shown potential to significantly improve the therapeutic impact on colitis. Mechanistically, it has been found that this system degrades the NLRP3 protein through the autophagy pathway by recruiting the E3 ligase, mitogen-activated protein kinase kinase 1 (MAP3K1), and the autophagy receptor protein optineurin (OPTN). Furthermore, our findings have indicated that the degradation of macrophage NLRP3 inhibits its M1-type polarization, which in turn hinders the colitis process. The system that we have devised has demonstrated potential to address the urgent need for the treatment of colitis, as well as other diseases related to macrophage NLRP3 dysregulation.

CD1d-iNKT Axis in Infectious Diseases: Lessons Learned From the Past

CD1d is an antigen-presenting molecule that presents lipid or glycolipid antigens to iNKT cells, a distinct subset of T lymphocytes characterised by their innate-like properties and restricted use of Vα, Jα and Vβ segments. The CD1d-iNKT axis represents an interesting aspect of the immune system with significant potential for therapeutic interventions against infectious diseases. Upon recognition of lipid antigens, iNKT cells initiate rapid and potent immune responses, releasing a diverse array of cytokines such as IL-4, IL-13, IFN-γ etc. that profoundly influence immune reactions against various pathogens, including bacteria and parasites, bridging innate and adaptive immunity. We identify and describe the key features of lipidic antigens and their derivatives that determine the nature of their antigenicity. Furthermore, modulating CD1d-driven iNKT cell responses by an array of lipid and glycolipid antigens holds promise as adjunctive therapy to existing antimicrobial treatments. Understanding the complexities of the CD1d-iNKT axis and exploiting its therapeutic potential in the case of infectious diseases could lead to innovative immunotherapeutic strategies, ushering in a new era of immunotherapy against pathogenic insults.

Piezo1-specific Deletion in Macrophage Protects the Progression of Chronic Inflammatory Bowel Disease in Mice

BACKGROUND & AIMS

Piezo1, a recently identified mechanically activated nonselective cation channel protein, demonstrates sensitivity to various mechanical stimuli, such as matrix stiffness and shear stress. Although accumulating evidence implicates Piezo1 channels in numerous physiologic and pathophysiologic processes, its involvement in dextran sulfate sodium (DSS)-induced acute and chronic inflammatory bowel disease (IBD) remains incompletely understood. This study aimed to investigate the effect of Piezo1 channels in macrophage polarization and its associated functions in IBD.

METHODS

DSS-induced inflammatory bowel disease model was established in Piezo1td/Tdt or Piezo1fl/fl and Piezo1△LysM male mice. Additionally, bone marrow-derived macrophages from Piezo1fl/fl and Piezo1△LysM male mice were isolated to elucidate the downstream targets of Piezo1 and the associated underlying molecular mechanisms.

RESULTS

Our findings revealed that Piezo1 deficiency in macrophages could protect mice from DSS-induced chronic IBD, as evidenced by improved colon length and the preservation of colon structure. The mitigation of inflammation during chronic IBD progression was observed with Piezo1 deficiency in macrophages, characterized by reduced macrophage accumulation, M1 macrophage polarization, T helper 1 infiltration, and decreased inflammatory cytokine secretion. Further investigations unveiled that Piezo1-deficient macrophages inhibit the expression and activity of Nod-like receptor protein 3 and nuclear factor kappa B in colon tissues and bone marrow-derived macrophages while regulating the nuclear translocation of p65. Conversely, macrophage Piezo1 activation enhanced inflammatory cytokine secretion by activating Nod-like receptor protein 3/nuclear factor kappa B pathways.

CONCLUSIONS

Myeloid Piezo1 mediates colonic immune response, and disrupting Piezo1 inhibits the progression of chronic IBD. This study provides hitherto undocumented evidence of the pivotal role of macrophage Piezo1 channels in regulating the progression of chronic IBD. Targeting macrophage Piezo1 may offer a promising therapeutic strategy against chronic IBD.

Pulchinenoside B4 alleviates DSS-induced colitis by inhibiting CD1d-dependent NLRP3 inflammasome activation in macrophages

Ulcerative colitis (UC) represents a significant challenge to global health, underscoring the importance of developing novel alternative anti-colitis agents. Inhibition of the NLRP3 inflammasome in macrophages has emerged as a potential therapeutic strategy for UC. Pulchinenoside B4 (PB4) is a major component of traditional medicinal plants that demonstrated to possess promising anti-inflammatory properties. The aim of the present study was to assess whether PB4 alleviates dextran sodium sulfate (DSS)-induced colitis by inhibiting the NLRP3 inflammasome in macrophages and its potential molecular mechanism. We constructed DSS-induced colitis in C57BL/6 mice, and isolated mouse intestinal macrophages and epithelial cells to investigate the effect of PB4 on NLRP3 inflammasome, and confirmed our findings in DSS-induced NLRP3-/- mice. In addition, we constructed lipopolysaccharides (LPS)-induced macrophages in vitro and identified the target and molecular mechanism of PB4 through biolayer interference (BLI) and cell thermal migration (CETSA) in conjunction with dss induced macrophage-specific CD1d depletion (CD1d-/-) colitis. This study showed that PB4 had a strong anti-inflammatory effect on WT mice induced by DSS, but the protective effect on NLRP3-/- mice was no longer enhanced. Interestingly, PB4 inhibited the activation of NLRP3 inflammasome in colon macrophages without affecting intestinal epithelial cells. Mechanistically, PB4 may target CD1d, thereby reducing the AKT-STAT1-PRDX1-NF-κB signaling pathway and ultimately inhibiting the activation of the NLRP3 inflammasome. Macrophage-specific CD1d loss has been shown to reverse the protective effects of PB4. These findings have paved the way for the development of CD1d/NLRP3-based novel anti-colitis agents and will facilitate the future clinical translation of the plant-derived drug PB4.

An oral probiotic vaccine loaded by Lactobacillus casei effectively increases defense against GCRV infection in grass carp

For a long time, grass carp culture in China has been severely affected by Grass Carp hemorrhagic disease caused by Grass Carp Reovirus (GCRV). At present, vaccines have been widely used for protecting aquatic organisms against infectious diseases, among which oral immunization with Lactobacillus casei is safe and highly effective. This vaccination route has the advantages of easy administration and noninvasive delivery. In this study, the recombinant LC-pVE5523-VP5 was constructed by using the outer capsid protein VP5 of GCRV as the immunogen and pVE5523 as the secretory expression vector. The bacterial powder was prepared from fermented broth by using the vacuum freeze-drying technology. The dried bacterial powder was subsequently mixed with feed and then pressed to pellets. After oral administration of the feed mixed with the recombinant L.casei powder, the expression of the immune-related genes (IFN I, IgM et al.) in grass carp was upregulated significantly. With the increased duration of oral immunization period, serum IgM level was also increased in grass carp. The survival analysis was carried out on the basis of grass carp in response to GCRV challenge. The result showed that the survival rate in the immunized group (74 %) was significantly higher than that in the control group (35 %). The amount of virus replication was also investigated in vaccine-treated fish. The result suggested that the virus content in fish tissue was also significantly less than that of the non-immunized group. The LC-pVE5523-VP5 was still present in the fish intestines 15 days after vaccination. These results indicated that the oral LC-pVE5523-VP5 can effectively protect grass carps from GCRV infection.

Exosomes derived from diabetic microenvironment-preconditioned mesenchymal stem cells ameliorate nonalcoholic fatty liver disease and inhibit pyroptosis of hepatocytes

AIM

Pyroptosis, a type of programmed cell death, is a key mechanism underlying non-alcoholic fatty liver disease (NAFLD). Mesenchymal stem cell (MSC)-derived exosomes (MSC-Exos) have the potential to ameliorate NAFLD, an effect that is enhanced by curcumin preconditioning. We previously reported that diabetic microenvironment preconditioning enhances the secretion capacity and anti-inflammatory activity of MSCs. Therefore, we hypothesized that MSC-Exos would inhibit hepatocyte pyroptosis and thereby ameliorate NAFLD, and that diabetic microenvironment preconditioning would enhance these effects.

METHODS

MSCs were preconditioned in a diabetic microenvironment (pMSCs). MSC-Exos and pMSC-Exos collected from MSCs or pMSCs were applied to methionine- and choline-deficient (MCD)-induced NAFLD mice and in vitro models involving induction with lipopolysaccharide or palmitic acid to mimic hepatic steatosis and injury. MCC950 treatment was used as a positive control. We analyzed the characteristics of NAFLD and pyroptosis markers. Protein profiles of MSC-Exos and pMSC-Exos were evaluated by label-free quantitative proteomics.

RESULTS

In vivo, MSC-Exos partially attenuated inflammation and fibrosis, but not lipid deposition and NAFLD progression in the livers of NAFLD mice. pMSC-Exos significantly improved lipid metabolism, hepatic steatosis, inflammation, and fibrosis but also retarded the progression of NAFLD. Pyroptosis was upregulated in the liver of NAFLD mice. MSC-Exos and pMSC-Exos inhibited pyroptosis, and the effect of the latter was greater than that of the former. In vitro, MSC-Exos and pMSC-Exos ameliorated hepatocyte steatosis, lipid metabolism disorder, and inflammation, and pMSC-Exos exerted a greater inhibitory effect on hepatocyte pyroptosis than MSC-Exos did, which were remitted after inhibition of peroxiredoxin-1 (PRDX-1).

CONCLUSION

MSC-Exos ameliorated NAFLD and inhibited hepatocyte pyroptosis by downregulating the NLRP3/Caspase-1/GSDMD pathway, effects enhanced by pMSC-Exos, partly due to PRDX-1 upregulation.

ASB3 expression aggravates inflammatory bowel disease by targeting TRAF6 protein stability and affecting the intestinal microbiota

E3 ubiquitin ligase (E3) plays a vital role in regulating inflammatory responses by mediating ubiquitination. Previous studies have shown that ankyrin repeat and SOCS box-containing protein 3 (ASB3) is involved in immunomodulatory functions associated with cancer. However, the impact of ASB3 on the dynamic interplay of microbiota and inflammatory responses in inflammatory bowel disease (IBD) is unclear. Here, we systematically identify the E3 ligase ASB3 as a facilitative regulator in the development and progression of IBD. We observed that ASB3 exhibited significant upregulation in the lesions of patients with IBD. ASB3-/- mice are resistant to dextran sodium sulfate-induced colitis. IκBα phosphorylation levels and production of proinflammatory factors IL-1β, IL-6, and TNF-α were reduced in the colonic tissues of ASB3-/- mice compared to WT mice. This colitis-resistant phenotype was suppressed after coprophagic microbial transfer and reversed after combined antibiotics removed the gut commensal microbiome. Mechanistically, ASB3 specifically catalyzes K48-linked polyubiquitination of TRAF6 in intestinal epithelial cells. In contrast, in ASB3-deficient organoids, the integrity of the TRAF6 protein is shielded, consequently decelerating the onset of intestinal inflammation. ASB3 is associated with dysregulation of the colitis microbiota and promotes proinflammatory factors' production by disrupting TRAF6 stability. Strategies to limit the protein level of ASB3 in intestinal epithelial cells may help in the treatment of colitis.

IMPORTANCE

Ubiquitination is a key process that controls protein stability. We determined the ubiquitination of TRAF6 by ASB3 in intestinal epithelial cells during colonic inflammation. Inflammatory bowel disease patients exhibit upregulated ASB3 expression at focal sites, supporting the involvement of degradation of TRAF6, which promotes TLR-Myd88/TRIF-independent NF-κB aberrant activation and intestinal microbiota imbalance. Sustained inflammatory signaling in intestinal epithelial cells and dysregulated protective probiotic immune responses mediated by ASB3 collectively contribute to the exacerbation of inflammatory bowel disease. These findings provide insights into the pathogenesis of inflammatory bowel disease and suggest a novel mechanism by which ASB3 increases the risk of colitis. Our results suggest that future inhibition of ASB3 in intestinal epithelial cells may be a novel clinical strategy.

Intratumoral NKT cell accumulation promotes antitumor immunity in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDA) is a potentially lethal disease lacking effective treatments. Its immunosuppressive tumor microenvironment (TME) allows it to evade host immunosurveillance and limits response to immunotherapy. Here, using the mouse KRT19-deficient (sgKRT19-edited) PDA model, we find that intratumoral accumulation of natural killer T (NKT) cells is required to establish an immunologically active TME. Mechanistically, intratumoral NKT cells facilitate type I interferon (IFN) production to initiate an antitumor adaptive immune response, and orchestrate the intratumoral infiltration of T cells, dendritic cells, natural killer cells, and myeloid-derived suppressor cells. At the molecular level, NKT cells promote the production of type I IFN through the interaction of their CD40L with CD40 on myeloid cells. To evaluate the therapeutic potential of these observations, we find that administration of folinic acid to mice bearing PDA increases NKT cells in the TME and improves their response to anti-PD-1 antibody treatment. In conclusion, NKT cells have an essential role in the immune response to mouse PDA and are potential targets for immunotherapy.

Gut Microbiota Alleviates Intestinal Injury Induced by Extended Exposure to Light via Inhibiting the Activation of NLRP3 Inflammasome in Broiler Chickens

Light pollution is a potential risk for intestinal health in humans and animals. The gut microbiota is associated with the development of intestinal inflammation induced by extended exposure to light, but the underlying mechanism is not yet clear. The results of this study showed that extended exposure to light (18L:6D) damaged intestinal morphology, downregulated the expression of tight junction proteins, and upregulated the expression of the NLRP3 inflammasome and the concentration of pro-inflammatory cytokines. In addition, extended exposure to light significantly decreased the abundance of Lactobacillus, Butyricicoccus, and Sellimonas and increased the abundance of Bifidobacterium, unclassified Oscillospirales, Family_XIII_UCG-001, norank_f__norank_o__Clostridia_vadinBB60_group, and Defluviitaleaceae_UCG-01. Spearman correlation analysis indicated that gut microbiota dysbiosis positively correlated with the activation of the NLRP3 inflammasome. The above results indicated that extended exposure to light induced intestinal injury by NLRP3 inflammasome activation and gut microbiota dysbiosis. Antibiotic depletion intestinal microbiota treatment and cecal microbiota transplantation (CMT) from the 12L:12D group to 18L:6D group indicated that the gut microbiota alleviated intestinal inflammatory injury induced by extended exposure to light via inhibiting the activation of the NLRP3 inflammasome. In conclusion, our findings indicated that the gut microbiota can alleviate intestinal inflammation induced by extended exposure to light via inhibiting the activation of the NLRP3 inflammasome.

Low-Shear Stress Promotes Atherosclerosis via Inducing Endothelial Cell Pyroptosis Mediated by IKKε/STAT1/NLRP3 Pathway

Atherosclerosis is initiated by vascular endothelial dysfunction, and low-shear stress (LSS) of blood flow is a key factor leading to endothelial dysfunction. Growing evidence suggests that endothelial cell pyroptosis plays an important role in the development of atherosclerosis. Studies have shown that low-shear stress can induce endothelial cell pyroptosis, but the exact mechanism remains unclear. Our experiments demonstrated that low-shear stress induced endothelial cell pyroptosis and the phosphorylation of IκB kinase ε (IKKε). IKKε knockdown not only significantly attenuated atherosclerosis lesions of aortic arch areas in ApoE-/- mice fed with high cholesterol diets, but also markedly reduced endothelial cell pyroptosis and NLRP3 expression triggered by low-shear stress. Further mechanism studies showed that IKKε promoted the expression of NLRP3 via activating signal transducer and activator of transcription 1 (STAT1) and the subsequent binding of STAT1 to NLRP3 promoter region. These results suggest that low-shear stress plays a pro-atherosclerotic role by promoting endothelial cell pyroptosis through the IKKε/STAT1/NLRP3 pathway, which provides new insights into the formation of atherosclerosis.

CD1 molecules: Beyond antigen presentation

CD1 molecules are well known for their role in binding and presenting lipid antigens to mediate the activation of CD1-restricted T cells. However, much less appreciated is the fact that CD1 molecules can have additional "unconventional" roles which impact the activation and functions of CD1-expressing cells, ultimately controlling tissue homeostasis as well as the progression of inflammatory and infectious diseases. Some of these roles are mediated by so-called reverse signalling, by which crosslinking of CD1 molecules at the cell surface initiates intracellular signalling. On the other hand, CD1 molecules can also control metabolic and inflammatory pathways in CD1-expressing cells through cell-intrinsic mechanisms independent of CD1 ligation. Here, we review the evidence for "unconventional" functions of CD1 molecules and the outcomes of such roles for health and disease.

Contribution of NKT cells and CD1d-expressing cells in obesity-associated adipose tissue inflammation

Natural killer T (NKT) cell are members of the innate-like T lymphocytes and recognizes lipid antigens presented by CD1d-expressing cells. Obesity-associated inflammation in adipose tissue (AT) leads to metabolic dysfunction, including insulin resistance. When cellular communication is properly regulated among AT-residing immune cells and adipocytes during inflammation, a favorable balance of Th1 and Th2 immune responses is achieved. NKT cells play crucial roles in AT inflammation, influencing the development of diet-induced obesity and insulin resistance. NKT cells interact with CD1d-expressing cells in AT, such as adipocytes, macrophages, and dendritic cells, shaping pro-inflammatory or anti-inflammatory microenvironments with distinct characteristics depending on the antigen-presenting cells. Additionally, CD1d may be involved in the inflammatory process independently of NKT cells. In this mini-review, we provide a brief overview of the current understanding of the interaction between immune cells, focusing on NKT cells and CD1d signaling, which control AT inflammation both in the presence and absence of NKT cells. We aim to enhance our understanding of the mechanisms of obesity-associated diseases.

Cilostazol protects against degenerative cervical myelopathy injury and cell pyroptosis via TXNIP-NLRP3 pathway

Degenerative cervical myelopathy (DCM) is one of the most common and serious neurological diseases. Cilostazol has protective effects of anterior horn motor neurons and prevented the cell apoptosis. However, there was no literatures of Cilostazol on DCM. In this study, we established the DCM rat model to detect the effects of Cilostazol. Meanwhile, the neurobehavioral assessments, histopathology changes, inflammatory cytokines, Thioredoxin-interacting protein (TXNIP), NOD‑like receptor pyrin domain containing 3 (NLRP3) and pro-caspase-1 expressions were detected by Basso, Beattie, and Bresnahan score assessment, Hematoxylin and Eosin Staining, Enzyme-linked immunosorbent assay, immunofluorescence and Western blotting, respectively. After treated with Cilostazol, the Basso, Beattie, and Bresnahan (BBB) score, inclined plane test and forelimb grip strength in DCM rats were significantly increased meanwhile the histopathology injury and inflammatory cytokines were decreased. Additionally, TXNIP, NLRP3 and pro-caspase-1 expressions levels were decreased in Cilostazol treated DCM rats. Interestingly, the using of siTXNIP significantly changed inflammatory cytokines, TXNIP, NLRP3 and pro-caspase-1 expressions, however there was no significance between siTXNIP and Cilostazol + siTXNIP group. These observations showed that Cilostazol rescues DCM injury and ameliorates neuronal destruction mediated by TXNIP/NLRP3/caspase-1 and pro-inflammatory cytokines. As a result of our study, these findings provide further evidence that Cilostazol may represent promising therapeutic candidates for DCM.

Role of CD1d and iNKT cells in regulating intestinal inflammation

Invariant natural killer T (iNKT) cells, a subset of unconventional T cells that recognize glycolipid antigens in a CD1d-dependent manner, are crucial in regulating diverse immune responses such as autoimmunity. By engaging with CD1d-expressing non-immune cells (such as intestinal epithelial cells and enterochromaffin cells) and immune cells (such as type 3 innate lymphoid cells, B cells, monocytes and macrophages), iNKT cells contribute to the maintenance of immune homeostasis in the intestine. In this review, we discuss the impact of iNKT cells and CD1d in the regulation of intestinal inflammation, examining both cellular and molecular factors with the potential to influence the functions of iNKT cells in inflammatory bowel diseases such as Crohn's disease and ulcerative colitis.

The Role of Histone Deacetylases in NLRP3 Inflammasomesmediated Epilepsy

Epilepsy is one of the most common brain disorders that not only causes death worldwide, but also affects the daily lives of patients. Previous studies have revealed that inflammation plays an important role in the pathophysiology of epilepsy. Activation of inflammasomes can promote neuroinflammation by boosting the maturation of caspase-1 and the secretion of various inflammatory effectors, including chemokines, interleukins, and tumor necrosis factors. With the in-depth research on the mechanism of inflammasomes in the development of epilepsy, it has been discovered that NLRP3 inflammasomes may induce epilepsy by mediating neuronal inflammatory injury, neuronal loss and blood-brain barrier dysfunction. Therefore, blocking the activation of the NLRP3 inflammasomes may be a new epilepsy treatment strategy. However, the drugs that specifically block NLRP3 inflammasomes assembly has not been approved for clinical use. In this review, the mechanism of how HDACs, an inflammatory regulator, regulates the activation of NLRP3 inflammasome is summarized. It helps to explore the mechanism of the HDAC inhibitors inhibiting brain inflammatory damage so as to provide a potential therapeutic strategy for controlling the development of epilepsy.

Microbial sensing in the intestine

The gut microbiota plays a key role in host health and disease, particularly through their interactions with the immune system. Intestinal homeostasis is dependent on the symbiotic relationships between the host and the diverse gut microbiota, which is influenced by the highly co-evolved immune-microbiota interactions. The first step of the interaction between the host and the gut microbiota is the sensing of the gut microbes by the host immune system. In this review, we describe the cells of the host immune system and the proteins that sense the components and metabolites of the gut microbes. We further highlight the essential roles of pattern recognition receptors (PRRs), the G protein-coupled receptors (GPCRs), aryl hydrocarbon receptor (AHR) and the nuclear receptors expressed in the intestinal epithelial cells (IECs) and the intestine-resident immune cells. We also discuss the mechanisms by which the disruption of microbial sensing because of genetic or environmental factors causes human diseases such as the inflammatory bowel disease (IBD).

CD1d-dependent neuroinflammation impairs tissue repair and functional recovery following a spinal cord injury

Tissue damage resulting from a spinal cord injury (SCI) is primarily driven by a robust neuroimmune/neuroinflammatory response. This intricate process is mainly governed by a multitude of cytokines and cell surface proteins in the central nervous system (CNS). However, the critical components of the neuroimmune/neuroinflammatory response during SCI are still not well-defined. In this study, we investigated the impact of CD1d, an MHC class I-like molecule mostly known for presenting lipid antigens to natural killer T (NKT) cells and regulating immune/inflammatory responses, on neuroimmune/neuroinflammatory responses induced by SCI. We observed an increased expression of CD1d on various cell types within the spinal cord, including microglia/macrophages, oligodendrocytes (ODCs), and endothelial cells (DCs), but not on neurons or astrocytes post-SCI. In comparison to wildtype (WT) mice, a T10 contusive SCI in CD1d knockout (CD1dKO or Cd1d -/- ) mice resulted in markedly reduced proinflammatory cytokine release, microglia/macrophage activation and proliferation. Following SCI, the levels of inflammatory cytokines and activation/proliferation of microglia/macrophages were dramatically reduced, while anti-inflammatory cytokines such as IL-4 and growth factors like VEGF were substantially increased in the spinal cord tissues of CD1dKO mice when compared to WT mice. In the post-acute phase of SCI (day 7 post-SCI), CD1dKO mice had a significantly higher frequency of tissue-repairing macrophages, but not other types of immune cells, in the injured spinal cord tissues compared to WT mice. Moreover, CD1d-deficiency protected spinal cord neuronal cells and tissue, promoting functional recovery after a SCI. However, the neuroinflammation in WT mouse spinal cords was independent of the canonical CD1d/NKT cell axis. Finally, treatment of injured mice with a CD1d-specific monoclonal antibody significantly enhanced neuroprotection and improved functional recovery. Therefore, CD1d promotes the proinflammatory response following a SCI and represents a potential therapeutic target for spinal cord repair.

Significance Statement

The cell surface molecule, CD1d, is known to be recognized by cells of the immune system. To our knowledge, this is the first observation that the CD1d molecule significantly contributes to neuroinflammation following a spinal cord injury (SCI) in a manner independent of the CD1d/NKT cell axis. This is important, because this work reveals CD1d as a potential therapeutic target following an acute SCI for which there are currently no effective treatments.

NOD-like receptors mediate homeostatic intestinal epithelial barrier function: promising therapeutic targets for inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic gastrointestinal inflammatory disease that involves host genetics, the microbiome, and inflammatory responses. The current consensus is that the disruption of the intestinal mucosal barrier is the core pathogenesis of IBD, including intestinal microbial factors, abnormal immune responses, and impaired intestinal mucosal barrier. Cumulative data show that nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs) are dominant mediators in maintaining the homeostasis of the intestinal mucosal barrier, which play critical roles in sensing the commensal microbiota, maintaining homeostasis, and regulating intestinal inflammation. Blocking NLRs inflammasome activation by botanicals may be a promising way to prevent IBD progression. In this review, we systematically introduce the multiple roles of NLRs in regulating intestinal mucosal barrier homeostasis and focus on summarizing the activities and potential mechanisms of natural products against IBD. Aiming to propose new directions on the pathogenesis and precise treatment of IBD.

Deubiquitinase OTUD6A in macrophages promotes intestinal inflammation and colitis via deubiquitination of NLRP3

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract, which has been shown to increase the incidence of colorectal cancer. Recent studies have highlighted the role of ubiquitination, a post-translational modification, in the occurrence and development of colonic inflammation. Ovarian tumor deubiquitinase 6 A (OTUD6A) is a deubiquitinating enzyme, which regulates cell proliferation and tumorigenesis. In this study, we investigated the expression and role of OTUD6A in IBD. Wide-type or Otud6a-/- mice were used to develop dextran sodium sulfate (DSS)- or 2,6,4-trinitrobenzene sulfonic acid (TNBS)-induced colitis model, as well as azoxymethane (AOM)/DSS-induced colitis-associated cancer model. Bone marrow-derived macrophages (BMDMs) were isolated from wild-type and Otud6a-/- mice to dissect molecular mechanisms. Our data show that OTUD6A deficiency attenuated DSS or TNBS-induced colitis, as well as AOM/DSS-induced colitis-related colon cancer in vivo. Bone marrow transplantation experiments further revealed that OTUD6A in myeloid cells was responsible for exacerbation of DSS-induced colitis. Mechanistically, OTUD6A directly bound to NACHT domain of NLRP3 inflammasome and selectively cleaved K48-linked polyubiquitin chains from NLRP3 at K430 and K689 to enhance the stability of NLRP3, leading to increased IL-1β level and inflammation. Taken together, our research identifies a new function of OTUD6A in the pathogenesis of colitis by promoting NLRP3 inflammasome activation, suggesting that OTUD6A could be a potential target for the treatment of IBD.

NLRP3 Inflammasome: A key contributor to the inflammation formation

Inflammation is an important part of the development of various organ diseases. The inflammasome, as an innate immune receptor, plays an important role in the formation of inflammation. Among various inflammasomes, the NLRP3 inflammasome is the most well studied. The NLRP3 inflammasome is composed of skeletal protein NLRP3, apoptosis-associated speck-like protein (ASC) and pro-caspase-1. There are three types of activation pathways: (1) "classical" activation pathway; (2) "non-canonical" activation pathway; (3) "alternative" activation pathway. The activation of NLRP3 inflammasome is involved in many inflammatory diseases. A variety of factors (such as genetic factors, environmental factors, chemical factors, viral infection, etc.) have been proved to activate NLRP3 inflammasome and promote the inflammatory response of the lung, heart, liver, kidney and other organs in the body. Especially, the mechanism of NLRP3 inflammation and its related molecules in its associated diseases remains not to be summarized, namely they may promote or delay inflammatory diseases in different cells and tissues. This article reviews the structure and function of the NLRP3 inflammasome and its role in various inflammations, including inflammations caused by chemically toxic substances.

Therapeutic modulation of V Set and Ig domain-containing 4 (VSIG4) signaling in immune and inflammatory diseases

Inflammation is the result of acute and chronic stresses, caused by emotional or physical trauma, or nutritional or environmental pollutants, and brings serious harm to human life and health. As an important cellular component of the innate immune barrier, the macrophage plays a key role in maintaining tissue homeostasis and promoting tissue repair by controlling infection and resolving inflammation. Several studies suggest that V Set and Ig domain-containing 4 is specifically expressed in tissue macrophages and is associated with a variety of inflammatory diseases. In this paper, we mainly summarize the recent research on V Set and Ig domain-containing 4 structures, functions, function and roles in acute and chronic inflammatory diseases, and provide a novel therapeutic avenue for the treatment of inflammatory diseases, including nervous system, urinary, respiratory and metabolic diseases.

Peroxiredoxin 1 alleviates oxygen-glucose deprivation/ reoxygenation injury in N2a cells via suppressing the JNK/caspase-3 pathway

Objectives

Cerebral ischemia/reperfusion (I/R) injury inevitably aggravates the initial cerebral tissue damage following a stroke. Peroxiredoxin 1 (Prdx1) is a representative protein of the endogenous antioxidant enzyme family that regulates several reactive oxygen species (ROS)-dependent signaling pathways, whereas the JNK/caspase-3 proapoptotic pathway has a prominent role during cerebral I/R injury. This study aimed to examine the potential mechanism of Prdx1 in Neuro 2A (N2a) cells following oxygen-glucose deprivation and reoxygenation (OGD/R) injury.

Materials and Methods

N2a cells were exposed to OGD/R to simulate cerebral I/R injury. Prdx1 siRNA transfection and the JNK inhibitor (SP600125) were used to interfere with their relative expressions. CCK-8 assay, flow cytometry, and lactate dehydrogenase (LDH) assay were employed to determine the viability and apoptosis of N2a cells. The intracellular ROS content was assessed using ROS Assay Kit. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analyses were conducted to detect the expression levels of Prdx1, JNK, phosphorylated JNK (p-JNK), and cleaved caspase-3.

Results

Firstly, Prdx1, p-JNK, and cleaved caspase-3 expression were significantly induced in OGD/R-exposed N2a cells. Secondly, the knockdown of Prdx1 inhibited cell viability and increased apoptosis rate, expression of p-JNK, and cleaved caspase-3 expression. Thirdly, SP600125 inhibited the JNK/caspase-3 signaling pathway and mitigated cell injury following OGD/R. Finally, SP600125 partially reversed Prdx1 down-regulation-mediated cleaved caspase-3 activation and OGD/R damage in N2a cells.

Conclusion

Prdx1 alleviates the injury to N2a cells induced by OGD/R via suppressing JNK/caspase-3 pathway, showing promise as a potential therapeutic for cerebral I/R injury.

CD1d-dependent rewiring of lipid metabolism in macrophages regulates innate immune responses

Alterations in cellular metabolism underpin macrophage activation, yet little is known regarding how key immunological molecules regulate metabolic programs in macrophages. Here we uncover a function for the antigen presenting molecule CD1d in the control of lipid metabolism. We show that CD1d-deficient macrophages exhibit a metabolic reprogramming, with a downregulation of lipid metabolic pathways and an increase in exogenous lipid import. This metabolic rewiring primes macrophages for enhanced responses to innate signals, as CD1d-KO cells show higher signalling and cytokine secretion upon Toll-like receptor stimulation. Mechanistically, CD1d modulates lipid import by controlling the internalization of the lipid transporter CD36, while blocking lipid uptake through CD36 restores metabolic and immune responses in macrophages. Thus, our data reveal CD1d as a key regulator of an inflammatory-metabolic circuit in macrophages, independent of its function in the control of T cell responses.

Essential Roles of Peroxiredoxin IV in Inflammation and Cancer

Peroxiredoxin IV (Prx4) is a 2-Cysteine peroxidase with ubiquitous expression in human tissues. Prx4 scavenges hydrogen peroxide and participates in oxidative protein folding in the endoplasmic reticulum. In addition, Prx4 is secreted outside the cell. Prx4 is upregulated in several cancers and is a potential therapeutic target. We have summarized historical and recent advances in the structure, function and biological roles of Prx4, focusing on inflammatory diseases and cancer. Oxidative stress is known to activate pro-inflammatory pathways. Chronic inflammation is a risk factor for cancer development. Hence, redox enzymes such as Prx4 are important players in the crosstalk between inflammation and cancer. Understanding molecular mechanisms of regulation of Prx4 expression and associated signaling pathways in normal physiological and disease conditions should reveal new therapeutic strategies. Thus, although Prx4 is a promising therapeutic target for inflammatory diseases and cancer, further research needs to be conducted to bridge the gap to clinical application.

mTOR-Mediated Autophagy Regulates Fumonisin B1-Induced Intestinal Inflammation via Pyroptosis In Vivo and In Vitro

Fumonisin B₁ (FB₁) is a fungal metabolite, which has an incremental detection rate in grains and feed worldwide. The nucleotide-binding oligomerization domain-like pyrin domain containing protein 3 (NLRP3) inflammasome is a critical element in pyroptosis activation, which participates in regulating enteritis. Meanwhile, autophagy is also engaged in intestinal inflammation. However, the function of pyroptosis and autophagy in FB₁-mediated enterotoxicity remains unclear. In this study, we explored the effects of FB₁ on enteritis and the underlying mechanism in vivo and in vitro. Our data showed that FB₁ exposure damaged the intestinal epithelium and promoted the secretion of inflammatory cytokines. Meanwhile, FB₁ exposure significantly upregulated the expression of pyroptosis-related genes. Then, MCC950, an inhibitor of NLRP3, significantly blocked FB₁-induced pyroptosis in IPEC-J2 cells. In addition, FB₁ treatment elevated the levels of autophagy. Moreover, the phosphorylation of the mammalian target of rapamycin (mTOR), an upstream protein of the autophagy pathway, was inhibited by FB₁ exposure. Notably, rapamycin, an inhibitor of mTOR, instead of MHY1485, an agonist of mTOR, could ameliorate FB₁-induced intestinal inflammatory injury and inhibit the upregulation of pyroptosis-related genes. In summary, we demonstrated that autophagy exhibited a protective effect against NLRP3 inflammasome-dependent pyroptosis on FB₁-induced enteritis. Our data clarify a favorable protective role for the activation of autophagy in FB₁ poisoning.

Alpha-Ketoglutarate Attenuates Colitis in Mice by Increasing Lactobacillus Abundance and Regulating Stem Cell Proliferation via Wnt-Hippo Signaling

SCOPE

Inflammatory bowel disease is an inflammatory gastrointestinal disorder associated with intestinal barrier damage, cell proliferation disorder, and dysbiosis of the intestinal microbiota. It remains unknown whether alpha-ketoglutarate (α-KG) can alleviate colitis in mice.

METHODS AND RESULTS

Six-week-old male C57BL/6 mice supplemented with or without 0.5% α-KG (delivered in the form of sodium salt) are subjected to drinking water or 2.5% DSS to induce colitis. The results show that α-KG administration is attenuated the severity of colitis, as is indicated by reduced body-weight loss, colon shortening and colonic hyperplasia, and repressed proinflammatory cytokine secretion in DSS-challenged mice. Additionally, DSS-induced increases in malondialdehyde (MDA) and hydrogen peroxide (H₂ O₂ ), and decreases in glutathione (GSH) levels are attenuated by α-KG administration. Further study shows that the protective effect of α-KG is associated with restoring gut barrier integrity by enhancing the expression of tight junction proteins, increasing Lactobacillus levels, and regulating gut hyperplasia by the Wnt-Hippo signaling pathway in DSS-induced colitis.

CONCLUSION

Collectively, the data provided herein demonstrate that α-KG administration is attenuated mucosal inflammation, barrier dysfunction, and gut microflora dysbiosis. This beneficial effect is associated with increased Lactobacillus levels and regulated colon hyperplasia by the Wnt-Hippo signaling pathway.

Multi-Omics Characterizes the Effects and Mechanisms of CD1d in Nonalcoholic Fatty Liver Disease Development

Nonalcoholic fatty liver disease (NAFLD) is a class of metabolic-associated liver diseases. Aberrant lipid consumption plays an important role in NAFLD pathogenesis. It has been shown CD1d can bind to multiple different lysophospholipids and associated with NAFLD progression. However, the mechanism of CD1d regulation in NAFLD is not completely understood. In this study, we established a NAFLD mouse model by feeding C57/BL6J mice a high-fat diet (HFD) for 24 weeks. Subsequently, we performed integrated transcriptomics and metabolomics analyses to thoroughly probe the role of CD1d in NAFLD progression. In the present study, we demonstrate that CD1d expression was significantly decreased in our murine model of NAFLD. Additionally, we show CD1d knockdown (CD1d KO) in HFD-fed wild-type (WT) mice induced NAFLD, which resulted in weight gain, exaggerated liver injury, and hepatic steatosis. We uncover the crucial roles of CD1d deficiency results in accumulated lipid accumulation. We further explored the CD1d deficiency in NAFLD regarding the transcriptional landscapes, microbiota environment, metabolomics change, and transcriptomics differences. In conclusion, our data demonstrate CD1d plays an important role in NAFLD pathogenesis and may represent a potential therapeutic target for the further therapy.

Adipose invariant NKT cells interact with CD1d-expressing macrophages to regulate obesity-related inflammation

Obesity is accompanied by and accelerated with chronic inflammation in adipose tissue, especially visceral adipose tissue (VAT). This low-level inflammation predisposes the host to the development of metabolic disease, most notably type 2 diabetes. We have focused on the capacity of glycolipid-reactive, CD1d-restricted natural killer T (NKT) cells to modulate obesity and its associated metabolic sequelae. We previously reported that CD1d knockout (KO) mice are partially protected against the development of obesity-associated insulin-resistance, and these findings were recapitulated in mice with an adipocyte-specific CD1d deficiency, suggesting that NKT cell-adipocyte interactions play a critical role in exacerbating disease. However, many other CD1d-expressing cells contribute to the in vivo responses of NKT cells to lipid antigens. In the present study, we examined the role of CD1d expression by macrophages (Mϕ) to the development of obesity-associated metabolic inflammation using LysMcre-cd1d1^f/f mice where the CD1d1 gene is disrupted in a Mϕ-specific manner. Unexpectedly, these animals contained a higher frequency of T-bet⁺ CD4⁺ T cells in VAT with increased production of Th1-cytokines that aggravated VAT inflammation. Mϕ from mutant mice displayed increased production of IL-12p40, suggesting M1 polarization. These findings indicate that interactions of CD1d on Mϕ with NKT cells play a beneficial role in obesity-associated VAT inflammation and insulin resistance with a sharp contrast to an aggravating role of CD1d on another type of antigen presenting cell, dendritic cells.

Aluminum chloride induces G0/G1 phase arrest via regulating the reactive oxygen species-depended non-canonical STAT1 pathway in hFOB1.19 cells

Treatment with aluminum chloride (AlCl₃) suppresses the growth of osteoblastic cells; however, the molecular mechanisms underlying the impact of AlCl₃ on cell growth have not been fully characterized. In this study, we observed that exposure of hFOB1.19 cells to AlCl₃ arrested cells at G₀/G₁ phase by inducing p21 expression. Further studies indicated that AlCl₃ upregulated the phosphorylation level of signal transducer and activator of transcription 1 (STAT1) at serine 727 site (Ser727). By chromatin immunoprecipitation and electrophoretic mobility shift assay, we found that AlCl₃ promoted STAT1/DNA binding activity to p21 promoter, thus resulting in the upregulation of p21. Moreover, siRNA-mediated knockdown of STAT1 attenuated p21 level induced by AlCl₃. Notably, using hFOB1.19 cells stably expressing dominant-negative STAT1 (Ser727Ala), we demonstrated that phosphorylation of STAT1 at Ser727 site is required for p21-mediated cycle arrest induced by AlCl₃. Mechanism investigation indicated that AlCl₃ stimulated the phosphorylation of JNK, and administration of JNK inhibitor SP600125 prevented AlCl₃-induced G₀/G₁ arrest through suppressing the phosphorylation of STAT1. Notably, pretreatment with N-acetyl-cysteine, a reactive oxygen species scavenger, conferred a significantly inhibitory effect on AlCl₃-mediated activation of JNK/STAT1 signaling pathway. Taken together, our findings provide the molecular mechanism for G₀/G₁ arrest induced by AlCl₃ in osteoblastic cells.

Sphingolipid metabolism during Toll-like receptor 4 (TLR4)-mediated macrophage activation

Macrophage activation in response to stimulation of Toll-like receptor 4 (TLR4) provides a paradigm for investigating energy metabolism that regulates the inflammatory response. TLR4-mediated pro-inflammatory macrophage activation is characterized by increased glycolysis and altered mitochondrial metabolism, supported by selective amino acid uptake and/or usage. Fatty acid metabolism remains as a highly complex rewiring that accompanies classical macrophage activation. TLR4 activation leads to de novo synthesis of fatty acids, which flux into sphingolipids, complex lipids that form the building blocks of eukaryotic cell membranes and regulate cell function. Here, we review the importance of TLR4-mediated de novo synthesis of membrane sphingolipids in macrophages. We first highlight fatty acid metabolism during TLR4-driven macrophage immunometabolism. We then focus on the temporal dynamics of sphingolipid biosynthesis and emphasize the modulatory role of some sphingolipid species (i.e. sphingomyelins, ceramides and glycosphingolipids) on the pro-inflammatory and pro-resolution phases of LPS/TLR4 activation in macrophages.

Soluble ligands as drug targets for treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD), which includes Crohn's disease and ulcerative colitis, is characterized by persistent inflammation in a hereditarily susceptible host. In addition to gastrointestinal symptoms, patients with IBD frequently suffer from extra-intestinal complications such as fibrosis, stenosis or cancer. Mounting evidence supports the targeting of cytokines for effective treatment of IBD. Cytokines can be included in a newly proposed classification "soluble ligands" that has become the third major target of human protein therapeutic drugs after enzymes and receptors. Soluble ligands have potential significance for research and development of anti-IBD drugs. Compared with traditional drug targets for IBD treatment, such as receptors, at least three factors contribute to the increasing importance of soluble ligands as drug targets. Firstly, cytokines are the main soluble ligands and targeting of them has demonstrated efficacy in patients with IBD. Secondly, soluble ligands are more accessible than receptors, which are embedded in the cell membrane and have complex tertiary membrane structures. Lastly, certain potential target proteins that are present in membrane-bound forms can become soluble following cleavage, providing further opportunities for intervention in the treatment of IBD. In this review, 49 drugs targeting 25 distinct ligands have been evaluated, including consideration of the characteristics of the ligands and drugs in respect of IBD treatment. In addition to approved drugs targeting soluble ligands, we have also assessed drugs that are in preclinical research and drugs inhibiting ligand-receptor binding. Some new types of targetable soluble ligands/proteins, such as epoxide hydrolase and p-selectin glycoprotein ligand-1, are also introduced. Targeting soluble ligands not only opens a new field of anti-IBD drug development, but the circulating soluble ligands also provide diagnostic insights for early prediction of treatment response. In conclusion, soluble ligands serve as the third-largest protein target class in medicine, with much potential for the drugs targeting them.

Inflammasome Regulation: Therapeutic Potential for Inflammatory Bowel Disease

Inflammasomes are multiprotein complexes formed to regulate the maturation of pro-inflammatory caspases, in response to intracellular or extracellular stimulants. Accumulating studies showed that the inflammasomes are implicated in the pathogenesis of inflammatory bowel disease (IBD), although their activation is not a decisive factor for the development of IBD. Inflammasomes and related cytokines play an important role in the maintenance of gut immune homeostasis, while its overactivation might induce excess immune responses and consequently cause tissue damage in the gut. Emerging studies provide evidence that some genetic abnormalities might induce enhanced NLRP3 inflammasome activation and cause colitis. In these cases, the colonic inflammation can be ameliorated by blocking NLRP3 activation or its downstream cytokine IL-1β. A number of natural products were shown to play a role in preventing colon inflammation in various experimental colitis models. On the other hand, lack of inflammasome function also causes intestinal abnormalities. Thus, an appropriate regulation of inflammasomes might be a promising therapeutic strategy for IBD intervention. This review aims at summarizing the main findings in these studies and provide an outline for further studies that might contribute to our understanding of the role of inflammasomes in the pathogenesis and therapeutic treatment of IBD.

Targeting the NLRP3 inflammasome as new therapeutic avenue for inflammatory bowel disease

The incidence and prevalence of inflammatory bowel disease (IBD) are increasing worldwide. Current approved medication for IBD treatment in the clinic mainly includes corticosteroids and neutralization antibodies to pro-inflammatory cytokines. However, drug resistance and severe side effect hinder long-term efficacy of these agents. The NOD-like receptor family pyrin domain containing protein 3 (NLRP3) is exclusively expressed in several inflammatory and autoimmune diseases. Excessive expression, aberrant activation, polymorphism, and gain-of-function mutation of the NLRP3 inflammasome contribute to IBD pathogenesis. In this article, we summarize the regulatory factors to NLRP3, and review recently developed NLRP3 inhibitors and their preclinical and clinical applications in treating inflammatory and autoimmune diseases. We present our views on the therapeutic potential of NLRP3 inhibitors as emerging therapeutic avenue for IBD.