Role and mechanism of the Dectin-1-mediated Syk/NF-κB signaling pathway in Talaromyces marneffei infection

Exploring the correlation between innate immune activation of inflammasome and regulation of pyroptosis after intracerebral hemorrhage: From mechanism to treatment

Stroke has emerged as the primary cause of disability and death globally in recent years. Intracerebral hemorrhage (ICH), a particularly severe kind of stroke, is occurring in an increasing number of people. The two main clinical treatments for ICH now in use are conservative pharmaceutical therapy and surgical intervention, both of which have risks and drawbacks. Consequently, it is crucial to look into the pathophysiology of ICH and consider cutting-edge therapeutic approaches. Recent research has revealed that pyroptosis is a newly identified type of cell death distinguished by the break of the cell membrane and the discharge of pro-inflammatory substances through different routes. Following ICH, glial cells experience pyroptosis, which worsens neuroinflammation. Hence, the onset and progression of ICH are strongly linked to pyroptosis, which is facilitated by different inflammasomes. It is essential to conduct a comprehensive investigation of ICH damage processes and uncover new targets for treatment. The impact and function of pyroptosis in ICH, as well as the activation and regulation of inflammasomes and their mediated pyroptosis pathways will be fully discussed in this review.

Yiqi Kaimi prescription regulates protein phosphorylation to promote intestinal motility in slow transit constipation

ETHNOPHARMACOLOGICAL RELEVANCE

The clinical efficacy of the Yiqi Kaimi prescription has been confirmed in slow transit constipation. However, the effects and biological mechanism of Yiqi Kaimi prescription are still unclear.

AIMS OF THE STUDY

To identify the effects of Yiqi Kaimi prescription on intestinal motility; To reveal the potential key targets and pathways of Yiqi Kaimi prescription for the treatment of slow transit constipation.

MATERIALS AND METHODS

The effects of Yiqi Kaimi prescription on slow transit constipation were investigated in a mouse model. The terminal ink propulsion experiment and fecal indocyanine green imaging was used to measure the intestinal transit time. Protein phosphorylation changes in colon tissues treated with Yiqi Kaimi prescription were detected using a Phospho Explorer antibody microarray. Bioinformatic analyses were performed using the Database for Annotation Visualization and Integrated Discovery (DAVID) and the Search Tool for the Retrieval of Interacting Genes (STRING). Western blot analysis and immunohistochemistry confirmed the observed changes in phosphorylation.

RESULT

s: Yiqi Kaimi prescription significantly increased the intestinal transit rate (P < 0.05 vs. model) and reduced the time to first discharge of feces containing fecal indocyanine green imaging in mice (P < 0.05 vs. model). The administration of Yiqi Kaimi prescription induced phosphorylation changes in 41 proteins, with 9 upregulated proteins and 32 downregulated proteins. Functional classification of the phosphorylated proteins with DAVID revealed that the critical biological processes included tyrosine protein kinases, positive regulation of calcium-mediated signaling and response to muscle stretch. The phosphorylation of the spleen tyrosine kinase (SYK) at Tyr348 increased 2.19-fold, which was the most significant change. The phosphorylation level of the transcription factor p65 (RELA) at Thr505 was decreased 0.57-fold. SYK was a hub protein in the protein-protein interaction network and SYK and RELA formed the core of the secondary subnetwork. The key protein phosphorylation after treatment with Yiqi Kaimi prescription were verified by Western blot analysis and immunohistochemistry.

CONCLUSION

Yiqi Kaimi prescription significantly enhanced intestinal motility. This effect was attributed to alterations in the phosphorylation levels of various target proteins. The observed changes in protein phosphorylation, including SYK and RELA, may serve as crucial factors in the treatment of slow transit constipation.

Fructo-oligosaccharide-mediated alteration in claudin expression in small intestinal absorptive Caco-2 cells is positively associated with the induction of inflammatory genes and the glucan receptor gene CLEC7A

OBJECTIVES

Indigestible carbohydrates may strengthen tight junctions (TJs) independently of intestinal bacteria. This study investigated whether indigestible carbohydrates (i.e., fructo-oligosaccharides [FOS]) promote TJs directly to intestinal absorptive Caco-2 cells and examined the association between the expression of genes constructing TJs and other genes using mRNA microarray analysis.

METHODS

Caco-2 cells at 1.0 × 105/mL were seeded in a type I collagen plate and cultured in high-glucose Dulbecco's modified Eagle medium (DMEM) supplemented with 10% fetal calf serum (FCS); the cells reached confluence at 7 d after seeding. Ten days after the cells reached confluency, they were cultured for 24 h in 10% FCS-containing DMEM medium supplemented with 0%, 5%, or 10% FOS. We performed mRNA microarray to identify the genes whose expression was altered by FOS. Subsequently, quantitative reverse transcription polymerase chain reaction was performed for these altered genes, including CLEC7A encoding the glucan receptor, and for the claudin (CLDN) family genes. The expression of CLDN2, CLDN4, and CLEC7A proteins was assessed using western blot analysis.

RESULTS

FOS decreased the mRNA and protein expression of CLDN2, which weakens TJs, and increased those of CLDN4, which strengthens TJs, in Caco-2 cells. FOS treatment (10%) reduced the mRNA expression of antioxidative genes and induced the expression of immune response-related genes, including CLEC7A, CCL2, and ITGA2. Furthermore, the expression of CLEC7A protein was enhanced by FOS.

CONCLUSIONS

Induction of TJ-strengthening CLDN4 and reduction of TJ-weakening CLDN2 by FOS treatment in small intestinal absorptive Caco-2 cells is positively associated with the induction of inflammatory genes, including CLEC7A.

Dectin-1 plays a deleterious role in high fat diet-induced NAFLD of mice through enhancing macrophage activation

The innate immune response and inflammation contribute to hepatic steatosis and non-alcoholic fatty liver disease (NAFLD). Dectin-1 is a pathogen recognition receptor in innate immunity. In this study, we investigated the role of Dectin-1 in the pathogenesis of NAFLD. We first showed that Dectin-1 expression was significantly elevated in liver tissues of patients with NASH. NAFLD was induced in mice by feeding high fat diet (HFD) for 24 weeks. At the end of treatment, mice were sacrificed, and their blood and liver tissues were collected for analyses. We showed HFD feeding also increased liver Dectin-1 levels in mice, associated with macrophage infiltration. Either gene knockout or co-administration of a Dectin-1 antagonist laminarin (150 mg/kg twice a day, ip, from 16^th week to 24^th week) largely protected the livers from HFD-induced lipid accumulation, fibrosis, and elaboration of inflammatory responses. In primary mouse peritoneal macrophages (MPMs), challenge with palmitate (PA, 200 μM), an abundant saturated fatty acid found in NAFLD, significantly activated Dectin-1 signaling pathway, followed by transcriptionally regulated production of pro-inflammatory cytokines. Dectin-1 was required for hepatic macrophage activation and inflammatory factor induction. Condition media generated from Dectin-1 deficient macrophages failed to cause hepatocyte lipid accumulation and hepatic stellate activation. In conclusion, this study provides the primary evidence supporting a deleterious role for Dectin-1 in NAFLD through enhancing macrophage pro-inflammatory responses and suggests that it can be targeted to prevent inflammatory NAFLD.

Expression of Cytokine Profiles in Human THP-1 Cells during Phase Transition of Talaromyces marneffei

Talaromyces marneffei, a dimorphic fungus, exhibits temperature-dependent growth, existing in a filamentous form at 25 °C and as a yeast at 37 °C. Several studies have highlighted the important roles of macrophages in defense against T. marneffei infection. However, the immune responses to the interaction of macrophages with T. marneffei cells during phase transition require further investigation. This study reports the expression of cytokine profiles in human THP-1 cells during infection by T. marneffei. THP-1 cells were infected with T. marneffei conidia at different multiplicity of infections (MOIs). Surviving conidia transformed into yeasts after phagocytosis by macrophages, and the number of yeasts gradually increased over 36 h. The transcription and secretion levels of pro- and anti-inflammatory cytokines were examined at different times by qRT-PCR and ELISA. Transcription levels of IL-8, IL-12, IL-1β, and TNF-α increased significantly at 12 or 24 h and then slightly decreased at 36 h. In contrast, the transcription levels of IL-6, IL-10, and TGF-β gradually increased at all MOIs. The levels of IL-6 and IL-10 secretion corresponded to their levels of transcription. These results indicated that as the number of intracellular yeasts increased, the infected macrophages first underwent slight M1 polarization before shifting to M2 polarization. This polarization transition was confirmed by the fungicidal ability and the expression of macrophage surface markers. By inducing the M2-type polarization of macrophages, the intracellular T. marneffei cells can successfully evade the immune response. Our study provides a novel insight into the immune characterization during the transition of T. marneffei infection and could further contribute to possible diagnostic and therapeutic interventions for this infection.

Inhibition of Dectin-1 Alleviates Neuroinflammatory Injury by Attenuating NLRP3 Inflammasome-Mediated Pyroptosis After Intracerebral Hemorrhage in Mice: Preliminary Study Results

BACKGROUND

Neuroinflammation plays an important role following intracerebral hemorrhage (ICH). NLRP3 inflammasome-mediated pyroptosis contributes to the mechanism of neuroinflammation. It has been reported that dendritic cell-associated C-type lectin-1 (Dectin-1) activation triggers inflammation in neurological diseases. However, the role of Dectin-1 on NLRP3 inflammasome-mediated pyroptosis after ICH remains unclear. Here, we aimed to explore the effect of Dectin-1 on NLRP3 inflammasome-mediated pyroptosis and neuroinflammation after ICH.

METHODS

Adult male C57BL/6 mice were used to establish the ICH model. Laminarin, an inhibitor of Dectin-1, was administered for intervention. Expression of Dectin-1 was evaluated by Western blot and immunofluorescence. Brain water content and neurobehavioral function were tested to assess brain edema and neurological performance. Western blot was conducted to evaluate the level of GSDMD-N. ELISA kits were used to measure the levels of IL-1β and IL-18. qRT-PCR and Western blot were performed to evaluate the expressions of NLRP3 inflammasome, IL-1β, and IL-18.

RESULTS

The expression of Dectin-1 increased following ICH, and Dectin-1 was expressed on microglia. In addition, inhibition of Dectin-1 by laminarin decreased brain edema and neurological impairment after ICH. Moreover, inhibition of Dectin-1 decreased the expression of pyroptosis-related protein, GSDMD-N, and inflammatory cytokines (IL-1β and IL-18). Mechanistically, Dectin-1 blockade inhibits NLRP3 inflammasome activation, thereby alleviating neuroinflammatory injury by attenuating NLRP3 inflammasome-mediated pyroptosis both in vivo and in vitro.

CONCLUSION

Our study indicates that the inhibition of Dectin-1 alleviates neuroinflammation by attenuating NLRP3 inflammasome-mediated pyroptosis after ICH.

Key thermally dimorphic fungal pathogens: shaping host immunity

Exposure to fungal pathogens from the environment is inevitable and with the number of at-risk populations increasing, the prevalence of invasive fungal infection is on the rise. An interesting group of fungal organisms known as thermally dimorphic fungi predominantly infects immunocompromised individuals. These potential pathogens are intriguing in that they survive in the environment in one form, mycelial phase, but when entering the host, they are triggered by the change in temperature to switch to a new pathogenic form. Considering the growing prevalence of infection and the need for improved diagnostic and treatment approaches, studies identifying key components of fungal recognition and the innate immune response to these pathogens will significantly contribute to our understanding of disease progression. This review focuses on key endemic dimorphic fungal pathogens that significantly contribute to disease, including Histoplasma, Coccidioides and Talaromyces species. We briefly describe their prevalence, route of infection and clinical presentation. Importantly, we have reviewed the major fungal cell wall components of these dimorphic fungi, the host pattern recognition receptors responsible for recognition and important innate immune responses supporting adaptive immunity and fungal clearance or the failure thereof.