Microbiota Sensing by Mincle-Syk Axis in Dendritic Cells Regulates Interleukin-17 and -22 Production and Promotes Intestinal Barrier Integrity

Lactiplantibacillus plantarum Regulates Intestinal Physiology and Enteric Neurons in IBS through Microbial Tryptophan Metabolites

Irritable bowel syndrome (IBS) is a prevalent functional gastrointestinal disorder characterized by visceral pain and gut dysmotility. However, the specific mechanisms by which Lactobacillus strains relieve IBS remain unclear. Here, we screened Lactobacillus strains from traditional Chinese fermented foods with potential IBS-alleviating properties through in vitro and in vivo experiments. We demonstrated that Lactiplantibacillus plantarum D266 (Lp D266) administration effectively modulates intestinal peristalsis, enteric neurons, visceral hypersensitivity, colonic inflammation, gut barrier function, and mast cell activation. Additionally, Lp D266 shapes gut microbiota and enhances tryptophan (Trp) metabolism, thus activating the aryl hydrocarbon receptor (AhR) and subsequently enhancing IL-22 production to maintain gut homeostasis. Mechanistically, Lp D266 potentially modulates colonic physiology and enteric neurons by microbial tryptophan metabolites. Further, our study indicates that combining Lp D266 with Trp synergistically ameliorates IBS symptoms. Together, our experiments identify the therapeutic efficacy of tryptophan-catabolizing Lp D266 in regulating gut physiology and enteric neurons, providing new insights into the development of probiotic-mediated nutritional intervention for IBS management.

Integration of Gut Mycobiota and Oxidative Stress to Decipher the Roles of C-Type Lectin Receptors in Inflammatory Bowel Diseases

BACKGROUND

Ulcerative colitis (UC) and Crohn's disease (CD) are two subtypes of inflammatory bowel disease (IBD) with rapidly increased incidence worldwide. Although multiple factors contribute to the occurrence and progression of IBD, the role of intestinal fungal species (gut mycobiota) in regulating the severity of these conditions has been increasingly recognized. C-type lectin receptors (CLRs) on hematopoietic cells, including Dectin-1, Dectin-2, Dectin-3, Mincle and DC-SIGN, are a group of pattern recognition receptors (PRRs) that primarily recognize fungi and mediate defense responses, such as oxidative stress. Recent studies have demonstrated the indispensable role of CLRs in protecting the colon from intestinal inflammation and mucosal damage.

METHODS AND RESULTS

This review provides a comprehensive overview of the role of CLRs in the pathogenesis of IBD. Given the significant impact of mycobiota and oxidative stress in IBD, this review also discusses recent advancements in understanding how these factors exacerbate or ameliorate IBD. Furthermore, the latest developments in CLR-guided IBD therapy are examined to highlight the modulation of CLRs in fungal recognition and oxidative burst during the IBD process.

CONCLUSION

This review emphasizes the importance of CLRs in IBD, offering new perspectives on the etiology and therapeutic approaches for this disease.

Gut microbiota as a key regulator of intestinal mucosal immunity

Gut microbiota is a complex microbial community with the ability of maintaining intestinal health. Intestinal homeostasis largely depends on the mucosal immune system to defense external pathogens and promote tissue repair. In recent years, growing evidence revealed the importance of gut microbiota in shaping intestinal mucosal immunity. Therefore, according to the existing findings, this review first provided an overview of intestinal mucosal immune system before summarizing the regulatory roles of gut microbiota in intestinal innate and adaptive immunity. Specifically, this review delved into the gut microbial interactions with the cells such as intestinal epithelial cells (IECs), macrophages, dendritic cells (DCs), neutrophils, and innate lymphoid cells (ILCs) in innate immunity, and T and B lymphocytes in adaptive immunity. Furthermore, this review discussed the main effects of gut microbiota dysbiosis in intestinal diseases and offered future research prospects. The review highlighted the key regulatory roles of gut microbiota in intestinal mucosal immunity via various host-microbe interactions, providing valuable references for the development of microbial therapy in intestinal diseases.

IL-17a promotes hepatocellular carcinoma by increasing FAP expression in hepatic stellate cells via activation of the STAT3 signaling pathway

Studies have shown that hepatic stellate cells (HSCs) and interleukin-17a (IL-17a) play important roles in liver tumorigenesis. In addition, fibroblast activation protein-α (FAP) has been shown to be a key regulator of hepatic stellate cell activation. In this study, in vivo and in vitro experiments were performed to verify the promoting effects of IL-17a administration, IL-17a overexpression, and FAP upregulation in HSCs on liver fibrosis and liver tumorigenesis. The cleavage under targets & release using nuclease (CUT&RUN) technique was used to verify the binding status of STAT3 to the FAP promoter. The in vitro studies showed that IL-17a activated HSCs and promoted HCC development and progression. FAP and IL-17a overexpression also activated HSCs, promoted HCC cell proliferation and migration, and inhibited HCC cell apoptosis. The in vivo studies suggested that IL-17a and FAP overexpression in HSCs facilitated liver tumor development and progression. The CUT&RUN results indicated that FAP expression was regulated by STAT3, which could bind to the FAP promoter region and regulate its transcription status. We concluded that IL-17a promoted HCC by increasing FAP expression in HSCs via activation of the STAT3 signaling pathway.

The immune interactions of gut glycans and microbiota in health and disease

The human digestive system harbors a vast diversity of commensal bacteria and maintains a symbiotic relationship with them. However, imbalances in the gut microbiota accompany various diseases, such as inflammatory bowel diseases (IBDs) and colorectal cancers (CRCs), which significantly impact the well-being of populations globally. Glycosylation of the mucus layer is a crucial factor that plays a critical role in maintaining the homeostatic environment in the gut. This review delves into how the gut microbiota, immune cells, and gut mucus layer work together to establish a balanced gut environment. Specifically, the role of glycosylation in regulating immune cell responses and mucus metabolism in this process is examined.

Blood and guts: how the intestinal microbiome shapes hematopoiesis and treatment of hematologic disease

ABSTRACT

Over the past 10 years, there has been a marked increase in recognition of the interplay between the intestinal microbiome and the hematopoietic system. Despite their apparent distance in the body, a large literature now supports the relevance of the normal intestinal microbiota to steady-state blood production, affecting both hematopoietic stem and progenitor cells as well as differentiated immune cells. Microbial metabolites enter the circulation where they can trigger cytokine signaling that influences hematopoiesis. Furthermore, the state of the microbiome is now recognized to affect outcomes from hematopoietic stem cell transplant, immunotherapy, and cellular therapies for hematologic malignancies. Here we review the mechanisms by which microbiotas influence hematopoiesis in development and adulthood as well as the avenues by which microbiotas are thought to impact stem cell transplant engraftment, graft-versus-host disease, and efficacy of cell and immunotherapies. We highlight areas of future research that may lead to reduced adverse effects of antibiotic use and improved outcomes for patients with hematologic conditions.

Myeloid C-type lectin receptors in innate immune recognition

C-type lectin receptors (CLRs) expressed by myeloid cells constitute a versatile family of receptors that play a key role in innate immune recognition. Myeloid CLRs exhibit a remarkable ability to recognize an extensive array of ligands, from carbohydrates and beyond, and encompass pattern-associated molecular patterns (PAMPs), damage-associated molecular patterns (DAMPs), and markers of altered self. These receptors, classified into distinct subgroups, play pivotal roles in immune recognition and modulation of immune responses. Their intricate signaling pathways orchestrate a spectrum of cellular responses, influencing processes such as phagocytosis, cytokine production, and antigen presentation. Beyond their contributions to host defense in viral, bacterial, fungal, and parasitic infections, myeloid CLRs have been implicated in non-infectious diseases such as cancer, allergies, and autoimmunity. A nuanced understanding of myeloid CLR interactions with endogenous and microbial triggers is starting to uncover the context-dependent nature of their roles in innate immunity, with implications for therapeutic intervention.

Gut microbiota and acute kidney injury: immunological crosstalk link

The gut microbiota, often called the "forgotten organ," plays a crucial role in bidirectional communication with the host for optimal physiological function. This communication helps regulate the host's immunity and metabolism positively and negatively. Many factors influence microbiota homeostasis and subsequently lead to an immune system imbalance. The correlation between an unbalanced immune system and acute diseases such as acute kidney injury is not fully understood, and the role of gut microbiota in disease pathogenesis is still yet uncovered. This review summarizes our understanding of gut microbiota, focusing on the interactions between the host's immune system and the microbiome and their impact on acute kidney injury.

Rutaecarpine ameliorates imiquimod-induced psoriasis-like dermatitis in mice associated with alterations in the gut microbiota

Psoriasis is accepted as a chronic, inflammatory, immune-mediated skin disease triggered by complex environmental and genetic factors. For a long time, disease recurrence, drug rejection, and high treatment costs have remained enormous challenges and burdens to patients and clinicians. Natural products with effective immunomodulatory and anti-inflammatory activities from medicinal plants have the potential to combat psoriasis and complications. Herein, an imiquimod (IMQ)-induced psoriasis-like dermatitis model is established in mice. The model mice are treated with 1% rutaecarpine (RUT) (external use) or the oral administration of RUT at different concentrations. Furthermore, high-throughput 16S rRNA gene sequencing is applied to analyze the changes in the diversity and composition of the gut microbiota. Based on the observation of mouse dorsal skin changes, RUT can protect against inflammation to improve psoriasis-like skin damage in mice. Additionally, RUT could suppress the expression levels of proinflammatory cytokines (IL-23, IL-17A, IL-22, IL-6, and IFN-α) within skin tissue samples. Concerning gut microbiota, we find obvious variations within the composition of gut microflora between IMQ-induced psoriasis mice and RUT-treated psoriasis mice. RUT effectively mediates the recovery of gut microbiota in mice induced by IMQ application. Psoriasis is linked to the production of several inflammatory cytokines and gut microbiome alterations. This research shows that RUT might restore gut microbiota homeostasis, reduce inflammatory cytokine production, and ameliorate psoriasis symptoms. In conclusion, the gut microbiota might be a therapeutic target or biomarker for psoriasis that aids in clinical diagnosis and therapy.

Atomic-Level Dissection of DC-SIGN Recognition of Bacteroides vulgatus LPS Epitopes

The evaluation of Bacteroides vulgatus mpk (BVMPK) lipopolysaccharide (LPS) recognition by DC-SIGN, a key lectin in mediating immune homeostasis, has been here performed. A fine chemical dissection of BVMPK LPS components, attained by synthetic chemistry combined to spectroscopic, biophysical, and computational techniques, allowed to finely map the LPS epitopes recognized by DC-SIGN. Our findings reveal BVMPK's role in immune modulation via DC-SIGN, targeting both the LPS O-antigen and the core oligosaccharide. Furthermore, when framed within medical chemistry or drug design, our results could lead to the development of tailored molecules to benefit the hosts dealing with inflammatory diseases.

Tailoring Tfh profiles enhances antibody persistence to a clade C HIV-1 vaccine in rhesus macaques

CD4 T follicular helper cells (Tfh) are essential for establishing serological memory and have distinct helper attributes that impact both the quantity and quality of the antibody response. Insights into Tfh subsets that promote antibody persistence and functional capacity can critically inform vaccine design. Based on the Tfh profiles evoked by the live attenuated measles virus vaccine, renowned for its ability to establish durable humoral immunity, we investigated the potential of a Tfh1/17 recall response during the boost phase to enhance persistence of HIV-1 Envelope (Env) antibodies in rhesus macaques. Using a DNA-prime encoding gp160 antigen and Tfh polarizing cytokines (interferon protein-10 (IP-10) and interleukin-6 (IL-6)), followed by a gp140 protein boost formulated in a cationic liposome-based adjuvant (CAF01), we successfully generated germinal center (GC) Tfh1/17 cells. In contrast, a similar DNA-prime (including IP-10) followed by gp140 formulated with monophosphoryl lipid A (MPLA) +QS-21 adjuvant predominantly induced GC Tfh1 cells. While the generation of GC Tfh1/17 cells with CAF01 and GC Tfh1 cells with MPLA +QS-21 induced comparable peak Env antibodies, the latter group demonstrated significantly greater antibody concentrations at week 8 after final immunization which persisted up to 30 weeks (gp140 IgG ng/ml- MPLA; 5500; CAF01, 2155; p<0.05). Notably, interferon γ+Env-specific Tfh responses were consistently higher with gp140 in MPLA +QS-21 and positively correlated with Env antibody persistence. These findings suggest that vaccine platforms maximizing GC Tfh1 induction promote persistent Env antibodies, important for protective immunity against HIV.

Maternal Supplementation with Ornithine Promotes Placental Angiogenesis and Improves Intestinal Development of Suckling Piglets

The blood vessels of the placenta are crucial for fetal growth. Here, lower vessel density and ornithine (Orn) content were observed in placentae for low-birth-weight fetuses versus normal-birth-weight fetuses at day 75 of gestation. Furthermore, the Orn content in placentae decreased from day 75 to 110 of gestation. To investigate the role of Orn in placental angiogenesis, 48 gilts (Bama pig) were allocated into four groups. The gilts in the control group were fed a basal diet (CON group), while those in the experimental groups were fed a basal diet supplemented with 0.05% Orn (0.05% Orn group), 0.10% Orn (0.10% Orn group), and 0.15% Orn (0.15% Orn group), respectively. The results showed that 0.15% Orn and 0.10% Orn groups exhibited increased birth weight of piglets compared with the CON group. Moreover, the 0.15% Orn group was higher than the CON group in the blood vessel densities of placenta. Mechanistically, Orn facilitated placental angiogenesis by regulating vascular endothelial growth factor-A (VEGF-A). Furthermore, maternal supplementation with 0.15% Orn during gestation increased the jejunal and ileal villi height and the concentrations of colonic propionate and butyrate in suckling piglets. Collectively, these results showed that maternal supplementation with Orn promotes placental angiogenesis and improves intestinal development of suckling piglets.

Potential therapeutic target for polysaccharide inhibition of colon cancer progression

In recent years, colon cancer has become one of the most common malignant tumors worldwide, posing a great threat to human health. Studies have shown that natural polysaccharides have rich biological activities and medicinal value, such as anti-inflammatory, anti-cancer, anti-oxidation, and immune-enhancing effects, especially with potential anti-colon cancer mechanisms. Natural polysaccharides can not only protect and enhance the homeostasis of the intestinal environment but also exert a direct inhibition effect on cancer cells, making it a promising strategy for treating colon cancer. Preliminary clinical experiments have demonstrated that oral administration of low and high doses of citrus pectin polysaccharides can reduce tumor volume in mice by 38% (p < 0.02) and 70% (p < 0.001), respectively. These results are encouraging. However, there are relatively few clinical studies on the effectiveness of polysaccharide therapy for colon cancer, and ensuring the effective bioavailability of polysaccharides in the body remains a challenge. In this article, we elucidate the impact of the physicochemical factors of polysaccharides on their anticancer effects and then reveal the anti-tumor effects and mechanisms of natural polysaccharides on colon cancer. Finally, we emphasize the challenges of using polysaccharides in the treatment of colon cancer and discuss future applications.

Synergistic Effect of Retinoic Acid and Lactoferrin in the Maintenance of Gut Homeostasis

Lactoferrin (LF) is a glycoprotein that binds to iron ions (Fe2+) and other metallic ions, such as Mg2+, Zn2+, and Cu2+, and has antibacterial and immunomodulatory properties. The antibacterial properties of LF are due to its ability to sequester iron. The immunomodulatory capability of LF promotes homeostasis in the enteric environment, acting directly on the beneficial microbiota. LF can modulate antigen-presenting cell (APC) biology, including migration and cell activation. Nonetheless, some gut microbiota strains produce toxic metabolites, and APCs are responsible for initiating the process that inhibits the inflammatory response against them. Thus, eliminating harmful strains lowers the risk of inducing chronic inflammation, and consequently, metabolic disease, which can progress to type 2 diabetes mellitus (T2DM). LF and retinoic acid (RA) exhibit immunomodulatory properties such as decreasing cytokine production, thus modifying the inflammatory response. Their activities have been observed both in vitro and in vivo. The combined, simultaneous effect of these molecules has not been studied; however, the synergistic effect of LF and RA may be employed for enhancing the secretion of humoral factors, such as IgA. We speculate that the combination of LF and RA could be a potential prophylactic alternative for the treatment of metabolic dysregulations such as T2DM. The present review focuses on the importance of a healthy diet for a balanced gut and describes how probiotics and prebiotics with immunomodulatory activity as well as inductors of differentiation and cell proliferation could be acquired directly from the diet or indirectly through the oral administration of formulations aimed to maintain gut health or restore a eubiotic state in an intestinal environment that has been dysregulated by external factors such as stress and a high-fat diet.

Composition of gut microbiota and non-alcoholic fatty liver disease: A systematic review and meta-analysis

The present systematic review and meta-analysis aimed to summarize the associations between gut microbiota composition and non-alcoholic fatty liver disease. To compare the differences between individuals with or without NAFLD, the standardized mean difference and 95% confidence interval were computed for each α-diversity index and relative abundance of gut microbes. The β-diversity indices were summarized in a qualitative manner. A total of 54 studies with 8894 participants were included. Overall, patients with NAFLD had moderate reduction in α-diversity indices including Shannon (SMD = -0.36, 95% CI = [-0.53, -0.19], p < 0.001) and Chao 1 (SMD = -0.42, 95% CI = [-0.68, -0.17], p = 0.001), but no significant differences were found for Simpson, observed species, phylogenetic diversity, richness, abundance-based coverage estimator, and evenness (p ranged from 0.081 to 0.953). Over 75% of the included studies reported significant differences in β-diversity. Although there was substantial interstudy heterogeneity, especially for analyses at the phylum, class, and family levels, the majority of the included studies showed alterations in the depletion of anti-inflammatory microbes (i.e., Ruminococcaceae and Coprococcus) and the enrichment of proinflammatory microbes (i.e., Fusobacterium and Escherichia) in patients with NAFLD. Perturbations in gut microbiota were associated with NAFLD, commonly reflected by a reduction in beneficial species and an increase in the pathogenic species.

Interaction between Gut Microbiota and Dendritic Cells in Colorectal Cancer

Colorectal cancer (CRC) is a malignancy that manifests in serial stages and has been observed to have an escalating incidence in modern societies, causing a significant global health problem. The development of CRC is influenced by various exogenous factors, including lifestyle, diet, nutrition, environment, and microbiota, that can affect host cells, including immune cells. Various immune dysfunctions have been recognized in patients with CRC at different stages of this disease. The signature of microbiota in the development of CRC-inflammation related to obesity, diet, and reactive host cells, such as dendritic cells (DCs)-has been highlighted by many studies. This study focuses on DCs, the primary cellular mediators linking innate and adaptive immune responses against cancer. In addition, this review focuses on the role of microbiota in dysbiosis and how it affects DCs and, in turn, the immune response and progression of CRC by stimulating different sets of T cells. Additionally, DCs' role in protecting this delicate balance is examined. This is to determine how gene yields of commensal microbiota may be critical in restoring this balance when disrupted. The stages of the disease and major checkpoints are discussed, as well as the role of the C-type lectin receptor of immature DCs pattern recognition receptor in CRC. Finally, based on a thorough examination of worldwide clinical studies and recent advancements in cancer immunotherapy, it is recommended that innovative approaches that integrate DC vaccination strategies with checkpoint inhibitors be considered. This approach holds great promise for improving CRC management.

Gut microbiota-mediated IL-22 alleviates metabolic inflammation

Low-grade chronic inflammation, also known as metabolic inflammation, promotes the development of metabolic diseases. Increasing evidence suggests that changes in gut microbes and metabolites disrupt the integrity of the gut barrier and exert significant effects on the metabolism of various tissues, including the liver and adipose tissue, thereby contributing to metabolic inflammation. We observed that IL-22 is a key signaling molecule that serves as a bridge between intestinal microbes and the host, effectively alleviating metabolic inflammation by modulating the host immunomodulatory network. Here, we focused on elucidating the underlying mechanisms by which the gut microbiota and their metabolites reduce inflammation via IL-22, highlighting the favorable impact of IL-22 on metabolic inflammation. Furthermore, we discuss the potential of IL-22 as a therapeutic target for the management of metabolic inflammation and related diseases.

PitNETs and the gut microbiota: potential connections, future directions

The role of the gut microbiome has been widely discussed in numerous works of literature. The biggest concern is the association of the gut microbiome with the central nervous system through the microbiome-brain-gut axis in the past ten years. As more and more research has been done on the relationship between the disease of the central nervous system and gut microbes. This fact is being revealed that gut microbes seem to play an important role from the onset and progression of the disease to clinical symptoms, and new treatments. As a special tumor of the central nervous system, pituitary neuroendocrine tumors (PitNETs)are closely related to metabolism, endocrinology, and immunity. These factors are the vectors through which intestinal microbes interact with the central nervous system. However, little is known about the effects of gut microbes on the PitNET. In this review, the relationship of gut microbiota in PitNETs is introduced, the potential effects of the gut-brain axis in this relationship are analyzed, and future research directions are presented.

Tailoring Tfh Profiles Enhances Antibody Persistence to a Clade C HIV-1 Vaccine in Rhesus Macaques

CD4 T follicular helper cells (Tfh) are essential for establishing serological memory and have distinct helper attributes that impact both the quantity and quality of the antibody response. Insights into Tfh subsets that promote antibody persistence and functional capacity can critically inform vaccine design. Based on the Tfh profiles evoked by the live attenuated measles virus vaccine, renowned for its ability to establish durable humoral immunity, we investigated the potential of a Tfh1/17 recall response during the boost phase to enhance persistence of HIV-1 Envelope (Env) antibodies in rhesus macaques. Using a DNA-prime encoding gp160 antigen and Tfh polarizing cytokines (interferon protein-10 (IP-10) and interleukin-6 (IL-6)), followed by a gp140 protein boost formulated in a cationic liposome-based adjuvant (CAF01), we successfully generated germinal center (GC) Tfh1/17 cells. In contrast, a similar DNA-prime (including IP-10) followed by gp140 formulated with monophosphoryl lipid A (MPLA)+QS-21 adjuvant predominantly induced GC Tfh1 cells. While the generation of GC Tfh1/17 cells with CAF01 and GC Tfh1 cells with MPLA+QS-21 induced comparable peak Env antibodies, the latter group demonstrated significantly greater antibody concentrations at week 8 after final immunization which persisted up to 30 weeks (gp140 IgG ng/ml- MPLA; 5500; CAF01, 2155; p <0.05). Notably, interferon γ+ Env-specific Tfh responses were consistently higher with gp140 in MPLA+QS-21 and positively correlated with Env antibody persistence. These findings suggest that vaccine platforms maximizing GC Tfh1 induction promote persistent Env antibodies, important for protective immunity against HIV.

Vaccination with an HIV T-Cell Immunogen (HTI) Using DNA Primes Followed by a ChAdOx1-MVA Boost Is Immunogenic in Gut Microbiota-Depleted Mice despite Low IL-22 Serum Levels

Despite the important role of gut microbiota in the maturation of the immune system, little is known about its impact on the development of T-cell responses to vaccination. Here, we immunized C57BL/6 mice with a prime-boost regimen using DNA plasmid, the Chimpanzee Adenovirus, and the modified Vaccinia Ankara virus expressing a candidate HIV T-cell immunogen and compared the T-cell responses between individuals with an intact or antibiotic-depleted microbiota. Overall, the depletion of the gut microbiota did not result in significant differences in the magnitude or breadth of the immunogen-specific IFNγ T-cell response after vaccination. However, we observed marked changes in the serum levels of four cytokines after vaccinating microbiota-depleted animals, particularly a significant reduction in IL-22 levels. Interestingly, the level of IL-22 in serum correlated with the abundance of Roseburia in the large intestine of mice in the mock and vaccinated groups with intact microbiota. This short-chain fatty acid (SCFA)-producing bacterium was significantly reduced in the vaccinated, microbiota-depleted group. Therefore, our results indicate that, although microbiota depletion reduces serum levels of IL-22, the powerful vaccine regime used could have overcome the impact of microbiota depletion on IFNγ-producing T-cell responses.

Gut microbiota regulate migration of lymphocytes from gut to lung

The community of microorganisms known as gut microbiota that lives in the intestine confers significant health benefits on its host, primarily in the form of immunological homeostasis regulation. Gut microbiota not only can shape immune responses in the gut but also in other organs. This review focus on the gut-lung axis. Aberrant gut microbiota development is associated with greater lung disease susceptibility and respiratory disease induced by a variety of pathogenic bacteria. They are known to cause changes in gut microbiota. Recent research has found that immune cells in the intestine migrate to distant lung to exert anti-infective effects. Moreover, evidence indicates that the gut microbiota and their metabolites influence intestinal immune cells. Therefore, we suspect that intestine-derived immune cells may play a significant role against pulmonary pathogenic infections by receiving instructions from gut microbiota.

Structural basis for plastic glycolipid recognition of the C-type lectin Mincle

Mincle (macrophage-inducible C-type lectin, CLEC4E) is a C-type lectin immune-stimulatory receptor for cord factor, trehalose dimycolate (TDM), which serves as a potent component of adjuvants. The recognition of glycolipids by Mincle, especially their lipid parts, is poorly understood. Here, we performed nuclear magnetic resonance analysis, revealing that titration of trehalose harboring a linear short acyl chain showed a chemical shift perturbation of hydrophobic residues next to the Ca-binding site. Notably, there were split signals for Tyr201 upon complex formation, indicating two binding modes for the acyl chain. In addition, most Mincle residues close to the Ca-binding site showed no observable signals, suggesting their mobility on an ∼ ms scale even after complex formation. Mutagenesis study supported two putative lipid-binding modes for branched acyl-chain TDM binding. These results provide novel insights into the plastic-binding modes of Mincle toward a wide range of glycol- and glycerol-lipids, important for rational adjuvant development.

The direct and gut microbiota-mediated effects of dietary bile acids on the improvement of gut barriers in largemouth bass (Micropterus salmoides)

Fish gut barrier damage under intensive culture model is a significant concern for aquaculture industry. This study aimed to investigate the effects of bile acids (BAs) on gut barriers in Micropterus salmoides. A germ-free (GF) zebrafish model was employed to elucidate the effects of the direct stimulation of BAs and the indirect regulations mediated by the gut microbiota on gut barrier functions. Four diets were formulated with BAs supplemented at 0, 150, 300 and 450 mg/kg, and these 4 diets were defined as control, BA150, BA300 and BA450, respectively. After 5 weeks of feeding experiment, the survival rate of fish fed with BA300 diet was increased (P < 0.05). Histological analysis revealed an improvement of gut structural integrity in the BA150 and BA300 groups. Compared with the control group, the expression of genes related to chemical barrier (mucin, lysozyme and complement 1) and physical barrier (occludin and claudin-4) was increased in the BA150 and BA300 groups (P < 0.05), and the expression of genes related to immunological barrier (interleukin [IL]-6, tumor growth factor β, IL-10, macrophage galactose-type lectin and immunoglobulin M [IgM]) was significantly increased in the BA300 group (P < 0.05), but the expression of genes related to chemical barrier (hepcidin) and immunological barrier (IL-1β, tumor necrosis factor-α, IL-6 and arginase) was significantly decreased in the BA450 group (P < 0.05). Gut microbiota composition analysis revealed that the abundance of Firmicutes was augmented prominently in the BA150 and BA300 groups (P < 0.05), while that of Actinobacteriota and Proteobacteria showed a downward trend in the BA150 and BA300 groups (P > 0.05). The results of the gut microbiota transferring experiment demonstrated an upregulation of gut barrier-related genes, including immunoglobulin Z/T (IgZ/T), IL-6, IL-1β and IL-10, by the gut microbiota transferred from the BA300 group compared with the control (P < 0.05). Feeding the BA300 diet directly to GF zebrafish resulted in enhanced expression of IgM, IgZ/T, lysozyme, occludin-2, IL-6 and IL-10 (P < 0.05). In conclusion, BAs can improve the gut barriers of fish through both direct and indirect effects mediated by the gut microbiota.

Peyer's patch phagocytes acquire specific transcriptional programs that influence their maturation and activation profiles

Peyer's patches (PPs) are secondary lymphoid organs in contact with the external environment via the intestinal lumen, thus combining antigen sampling and immune response initiation sites. Therefore, they provide a unique opportunity to study the entire process of phagocyte differentiation and activation in vivo. Here, we deciphered the transcriptional and spatial landscape of PP phagocyte populations from their emergence in the tissue to their final maturation state at homeostasis and under stimulation. Activation of monocyte-derived Lysozyme-expressing dendritic cells (LysoDCs) differs from that of macrophages by their upregulation of conventional DC (cDC) signature genes such as Ccr7 and downregulation of typical monocyte-derived cell genes such as Cx3cr1. We identified gene sets that distinguish PP cDCs from the villus ones and from LysoDCs. We also identified key immature, early, intermediate, and late maturation markers of PP phagocytes. Finally, exploiting the ability of the PP interfollicular region to host both villous and subepithelial dome emigrated cDCs, we showed that the type of stimulus, the subset, but also the initial location of cDCs shape their activation profile and thus direct the immune response. Our study highlights the importance of targeting the right phagocyte subset at the right place and time to manipulate the immune response.

Targeting Th17 cells: a promising strategy to treat oral mucosal inflammatory diseases

With the improved quality of life, oral health is under increased pressure. Numerous common oral mucosal diseases, such as oral lichen planus(OLP) and gingivitis, are related to the destruction of the oral immune barrier. The cytokines secreted by T-helper 17 (Th17) cells are essential for maintaining oral immune homeostasis and play essential roles in immune surveillance. When antigens stimulate the epithelium, Th17 cells expand, differentiate, and generate inflammatory factors to recruit other lymphocytes, such as neutrophils, to clear the infection, which helps to maintain the integrity of the epithelial barrier. In contrast, excessive Th17/IL-17 axis reactions may cause autoimmune damage. Therefore, an in-depth understanding of the role of Th17 cells in oral mucosa may provide prospects for treating oral mucosal diseases. We reviewed the role of Th17 cells in various oral and skin mucosal systemic diseases with oral characteristics, and based on the findings of these reports, we emphasize that Th17 cellular response may be a critical factor in inflammatory diseases of the oral mucosa. In addition, we should pay attention to the role and relationship of "pathogenic Th17" and "non-pathogenic Th17" in oral mucosal diseases. We hope to provide a reference for Th17 cells as a potential therapeutic target for treating oral mucosal inflammatory disorders in the future.

Lizhong decoction ameliorates pulmonary infection secondary to severe traumatic brain injury in rats by regulating the intestinal physical barrier and immune response

ETHNOPHARMACOLOGICAL RELEVANCE

The pathogenesis of pulmonary infection secondary to severe traumatic brain injury (sTBI) is closely related to damage to the intestinal barrier. Lizhong decoction (LZD) is a prominent traditional Chinese medicine (TCM) that is widely used in clinical treatment to regulate gastrointestinal movement and enhance resistance. Nevertheless, the role and mechanism of LZD in lung infection secondary to sTBI have yet to be elucidated.

AIM OF THE STUDY

Here, we evaluate the therapeutic effect of LZD on pulmonary infection secondary to sTBI in rats and discuss potential regulatory mechanisms.

MATERIALS AND METHODS

The chemical constituents of LZD were analyzed by ultra-high performance liquid chromatography-Q Exactive-tandem mass spectrometry(UPLC-QE-MS/MS). The efficacy of LZD on rats with lung infection secondary to sTBI was examined by changes in brain morphology, coma time, brain water content, mNSS score, colony counts, 16S rRNA/RNaseP/MRP30 kDa(16S/RPP30), myeloperoxidase (MPO) content and pathology of lung tissue. The concentration of fluorescein isothiocyanate(FITC)-dextran in serum and the contents of secretory immunoglobulin A (SIgA) in colon tissue were detected by enzyme-linked immunosorbent assay (ELISA). Subsequently, Alcian Blue Periodic acid Schiff (AB-PAS) was used to detect colonic goblet cells. Immunofluorescence (IF) was used to detect the expression of tight junction proteins. The proportions of CD3⁺ cell, CD4⁺CD8⁺ T cells, CD45⁺ cell and CD103+ cells in the colon were analyzed by flow cytometry (FC). In addition, colon transcriptomics were analyzed by Illumina mRNA-Seq sequencing. Real-time quantitative polymerase chain reaction (qRT‒PCR) was used to verify the genes associated with LZD alleviation of intestinal barrier function.

RESULTS

Twenty-nine chemical constituents of LZD were revealed with UPLC-QE-MS/MS analysis. Administration of LZD significantly reduced colony counts, 16S/RPP30 and MPO content in lung infection secondary to sTBI rats. In addition, LZD also reduced the serum FITC-glucan content and the SIgA content of the colon. Additionally, LZD significantly increased the number of colonic goblet cells and the expression of tight junction proteins. Furthermore, LZD significantly decreased the proportion of CD3⁺ cell, CD4⁺CD8⁺ T cells,CD45+ and CD103+ cells in colon tissue. Transcriptomic analysis identified 22 upregulated genes and 56 downregulated genes in sTBI compared to the sham group. The levels of seven genes were recovered after LZD treatment. qRT‒PCR successfully validated two genes (Jchain and IL-6) at the mRNA level.

CONCLUSION

LZD can improves sTBI secondary lung infection by regulating the intestinal physical barrier and immune response. Thees results suggested that LZD may be a prospective treatment for pulmonary infection secondary to sTBI.

Distinct Serum Immune Profiles Define the Spectrum of Acute and Chronic Pancreatitis From the Multicenter Prospective Evaluation of Chronic Pancreatitis for Epidemiologic and Translational Studies (PROCEED) Study

BACKGROUND & AIMS

Pancreatitis is a disease continuum, starting with acute pancreatitis (AP) and progressing in some cases to recurrent acute pancreatitis (RAP) and chronic pancreatitis (CP). Currently, there are no approved therapies or early diagnostic or prognostic biomarkers for pancreatitis. The current study examined whether patient serum immune profiling could identify noninvasive biomarkers and provide mechanistic insight into the disease continuum of pancreatitis.

METHODS

Using Olink immunoassay, we assessed the protein levels of 92 immune markers in serum samples from participants enrolled in the Prospective Evaluation of Chronic Pancreatitis for Epidemiologic and Translational Studies (PROCEED) study of the Chronic Pancreatitis, Diabetes, and Pancreatic Cancer (CPDPC) consortium. Samples (N = 231) were obtained from individuals without pancreatic disease (n = 56) and from those with chronic abdominal pain (CAP) (n = 24), AP (n = 38), RAP (n = 56), and CP (n = 57).

RESULTS

A total of 33 immune markers differentiated the combined pancreatitis groups from controls. Immune markers related to interleukin (IL) 17 signaling distinguished CP from AP and RAP. Similarly, the serum level of IL17A and C-C motif chemokine ligand 20 differentiated CP from CAP, suggesting the involvement of T helper 17 cells in CP pathogenesis. The receiver operator characteristic curve with 2 immune markers (IL17A and sulfotransferase 1A1) could differentiate CP from CAP (optimistic area under the curve = 0.78). The macrophage classical activation pathway elevated along the continuum of pancreatitis, suggesting an accumulation of proinflammatory signals over disease progression. Several immune markers were associated with smoking, alcohol, and diabetes status.

CONCLUSIONS

Immune profiling of serum samples from a large pancreatitis cohort led to identifying distinct immune markers that could serve as potential biomarkers to differentiate the varying pancreatitis disease states. In addition, the finding of IL17 signaling in CP could provide insight into the immune mechanisms underlying disease progression.

Prolonged dysbiosis and altered immunity under nutritional intervention in a physiological mouse model of severe acute malnutrition

Severe acute malnutrition (SAM) is a multifactorial disease affecting millions of children worldwide. It is associated with changes in intestinal physiology, microbiota, and mucosal immunity, emphasizing the need for multidisciplinary studies to unravel its full pathogenesis. We established an experimental model in which weanling mice fed a high-deficiency diet mimic key anthropometric and physiological features of SAM in children. This diet alters the intestinal microbiota (less segmented filamentous bacteria, spatial proximity to epithelium), metabolism (decreased butyrate), and immune cell populations (depletion of LysoDC in Peyer's patches and intestinal Th17 cells). A nutritional intervention leads to a fast zoometric and intestinal physiology recovery but to an incomplete restoration of the intestinal microbiota, metabolism, and immune system. Altogether, we provide a preclinical model of SAM and have identified key markers to target with future interventions during the education of the immune system to improve SAM whole defects.

A Review on Maternal and Infant Microbiota and Their Implications for the Prevention and Treatment of Allergic Diseases

Allergic diseases, which are closely related to the composition and metabolism of maternal and infant flora, are prevalent in infants worldwide. The mother's breast milk, intestinal, and vaginal flora directly or indirectly influence the development of the infant's immune system from pregnancy to lactation, and the compositional and functional alterations of maternal flora are associated with allergic diseases in infants. Meanwhile, the infant's own flora, represented by the intestinal flora, indicates and regulates the occurrence of allergic diseases and is altered with the intervention of allergic diseases. By searching and selecting relevant literature in PubMed from 2010 to 2023, the mechanisms of allergy development in infants and the links between maternal and infant flora and infant allergic diseases are reviewed, including the effects of flora composition and its consequences on infant metabolism. The critical role of maternal and infant flora in allergic diseases has provided a window for probiotics as a microbial therapy. Therefore, the uses and mechanisms by which probiotics, such as lactic acid bacteria, can help to improve the homeostasis of both the mother and the infant, and thereby treat allergies, are also described.

IgA deficiency destabilizes homeostasis toward intestinal microbes and increases systemic immune dysregulation

The ability of most patients with selective immunoglobulin A (IgA) deficiency (SIgAD) to remain apparently healthy has been a persistent clinical conundrum. Compensatory mechanisms, including IgM, have been proposed, yet it remains unclear how secretory IgA and IgM work together in the mucosal system and, on a larger scale, whether the systemic and mucosal anti-commensal responses are redundant or have unique features. To address this gap in knowledge, we developed an integrated host-commensal approach combining microbial flow cytometry and metagenomic sequencing (mFLOW-Seq) to comprehensively define which microbes induce mucosal and systemic antibodies. We coupled this approach with high-dimensional immune profiling to study a cohort of pediatric patients with SIgAD and household control siblings. We found that mucosal and systemic antibody networks cooperate to maintain homeostasis by targeting a common subset of commensal microbes. In IgA-deficiency, we find increased translocation of specific bacterial taxa associated with elevated levels of systemic IgG targeting fecal microbiota. Associated features of immune system dysregulation in IgA-deficient mice and humans included elevated levels of inflammatory cytokines, enhanced follicular CD4 T helper cell frequency and activation, and an altered CD8 T cell activation state. Although SIgAD is clinically defined by the absence of serum IgA, the symptomatology and immune dysregulation were concentrated in the SIgAD participants who were also fecal IgA deficient. These findings reveal that mucosal IgA deficiency leads to aberrant systemic exposures and immune responses to commensal microbes, which increase the likelihood of humoral and cellular immune dysregulation and symptomatic disease in patients with IgA deficiency.

Clec12a tempers inflammation while restricting expansion of a colitogenic commensal

Regulation of the microbiota is critical to intestinal health yet the mechanisms employed by innate immunity remain unclear. Here we show that mice deficient in the C-Type-lectin receptor, Clec12a developed severe colitis, which was dependent on the microbiota. Fecal-microbiota-transplantation (FMT) studies into germfree mice revealed a colitogenic microbiota formed within Clec12a -/- mice that was marked by expansion of the gram-positive organism, Faecalibaculum rodentium . Treatment with F. rodentium was sufficient to worsen colitis in wild-type mice. Macrophages within the gut express the highest levels of Clec12a. Cytokine and sequencing analysis in Clec12a -/- macrophages revealed heighten inflammation but marked reduction in genes associated with phagocytosis. Indeed, Clec12a -/- macrophages are impaired in their ability to uptake F. rodentium. Purified Clec12a had higher binding to gram-positive organisms such as F. rodentium . Thus, our data identifies Clec12a as an innate immune surveillance mechanism to control expansion of potentially harmful commensals without overt inflammation.

The role of IL-23/IL-17 axis in ischemic stroke from the perspective of gut-brain axis

Bidirectional communication between central nervous system (CNS) and intestine is mediated by nerve, endocrine, immune and other pathways in gut-brain axis. Many diseases of CNS disturb the homeostasis of intestine and gut microbiota. Similarly, the dysbiosis of intestinal and gut microbiota also promotes the progression and deterioration of CNS diseases. IL-23/IL-17 axis is an important inflammatory axis which is widely involved in CNS diseases such as experimental autoimmune encephalomyelitis (EAE), multiple sclerosis (MS), and ischemic stroke (IS). Attributing to the long anatomically distances between ischemic brain and gut, previous studies on IL-23/IL-17 axis in IS are rarely focused on intestinal tissues. However, recent studies have found that IL-17⁺T cells in CNS mainly originate from intestine. The activation and migration of IL-17⁺T cells to CNS is likely to be affected by the altered intestinal homeostasis. These studies promoted the attention of IL-23/IL-17 axis and gut-brain axis. IS is difficult to treat because of its extremely complex pathological mechanism. This review mainly discusses the relationship between IL-23/IL-17 axis and IS from the perspective of gut-brain axis. By analyzing the immune pathways in gut-brain axis, the activation of IL-23/IL-17 axis, the roles of IL-23/IL-17 axis in gut, CNS and other systems after stoke, this review is expected to provide new enlightenments for the treatment strategies of IS.

Immunity orchestrates a bridge in gut-brain axis of neurodegenerative diseases

Neurodegenerative diseases, in particular for Alzheimer's disease (AD), Parkinson's disease (PD) and Multiple sclerosis (MS), are a category of diseases with progressive loss of neuronal structure or function (encompassing neuronal death) leading to neuronal dysfunction, whereas the underlying pathogenesis remains to be clarified. As the microbiological ecosystem of the intestinal microbiome serves as the second genome of the human body, it is strongly implicated as an essential element in the initiation and/or progression of neurodegenerative diseases. Nevertheless, the precise underlying principles of how the intestinal microflora impact on neurodegenerative diseases via gut-brain axis by modulating the immune function are still poorly characterized. Consequently, an overview of initiating the development of neurodegenerative diseases and the contribution of intestinal microflora on immune function is discussed in this review.

Low lymphocyte-to-monocyte ratio, calcitriol level, and CD206 level predict the development of acute-on-chronic liver failure in patients cirrhosis with acute decompensation

BACKGROUND

Cirrhosis-related acute-on-chronic liver failure (ACLF) is associated with high morbidity and mortality rates. Prognostic models of ACLF have been developed; however, few studies have focused on the occurrence of ACLF. This study aimed to identify the factors that predict the development of ACLF, hepatic encephalopathy (HE), and infection in patients with cirrhosis.

METHODS

Patients with cirrhosis were enrolled, and the serum levels of calcitriol, Cluster of Differentiation 26 (CD206), and macrophage-inducible lectin receptor (Mincle) were measured, and lymphocyte-to-monocyte ratio (LMR) and neutrophil-to-lymphocyte ratio were calculated; all the patients were tracked for 6 months. A generalized estimating equation (GEE) was used to assess the factors associated with ACLF development, HE, and infection. The aforementioned model was derived based on immunological markers, and receiver operating characteristic analysis with area under the curve (AUC) was adopted to evaluate accuracy.

RESULTS

After screening 325 patients with cirrhosis, 65 patients were eligible. In the GEE model, low levels of calcitriol (odds ratio [OR] = 3.259; 95% confidence interval [CI] = 1.118-8.929) and CD206 (OR = 2.666; 95% CI = 1.082-6.567) were associated with the development of ACLF, and the LMR was a protective factor (OR = 0.356; 95% CI = 0.147-0.861). Low calcitriol levels were a risk factor for HE (OR = 3.827) and infection (OR = 2.489). LMR was found to be a protective factor against HE (OR = 0.388). An immunological model for the discrimination of ACLF development within 6 months was proposed, with an AUC of 0.734 (95% CI = 0.598-0.869).

CONCLUSION

Single and combined immunological markers, including low LMR and low levels of calcitriol and CD206, were promising for early prediction of the development of ACLF, HE, and infection in patients with cirrhosis.

S-layer proteins as immune players: tales from pathogenic and non-pathogenic bacteria

In bacteria, as in other microorganisms, surface compounds interact with different pattern recognition receptors expressed by host cells, which usually triggers a variety of cellular responses that result in immunomodulation. The S-layer is a two-dimensional macromolecular crystalline structure formed by (glyco)-protein subunits that covers the surface of many species of Bacteria and almost all Archaea. In Bacteria, the presence of S-layer has been described in both pathogenic and non-pathogenic strains. As surface components, special attention deserves the role that S-layer proteins (SLPs) play in the interaction of bacterial cells with humoral and cellular components of the immune system. In this sense, some differences can be predicted between pathogenic and non-pathogenic bacteria. In the first group, the S-layer constitutes an important virulence factor, which in turn makes it a potential therapeutic target. For the other group, the growing interest to understand the mechanisms of action of commensal microbiota and probiotic strains has prompted the studies of the role of the S-layer in the interaction between the host immune cells and bacteria bearing this surface structure. In this review, we aim to summarize the main latest reports and the perspectives of bacterial SLPs as immune players, focusing on those from pathogenic and commensal/probiotic most studied species.

Specific targeting of inflammatory osteoclastogenesis by the probiotic yeast S. boulardii CNCM I-745 reduces bone loss in osteoporosis

Bone destruction is a hallmark of chronic inflammation, and bone-resorbing osteoclasts arising under such a condition differ from steady-state ones. However, osteoclast diversity remains poorly explored. Here, we combined transcriptomic profiling, differentiation assays and in vivo analysis in mouse to decipher specific traits for inflammatory and steady-state osteoclasts. We identified and validated the pattern-recognition receptors (PRR) Tlr2, Dectin-1, and Mincle, all involved in yeast recognition as major regulators of inflammatory osteoclasts. We showed that administration of the yeast probiotic Saccharomyces boulardii CNCM I-745 (Sb) in vivo reduced bone loss in ovariectomized but not sham mice by reducing inflammatory osteoclastogenesis. This beneficial impact of Sb is mediated by the regulation of the inflammatory environment required for the generation of inflammatory osteoclasts. We also showed that Sb derivatives as well as agonists of Tlr2, Dectin-1, and Mincle specifically inhibited directly the differentiation of inflammatory but not steady-state osteoclasts in vitro. These findings demonstrate a preferential use of the PRR-associated costimulatory differentiation pathway by inflammatory osteoclasts, thus enabling their specific inhibition, which opens new therapeutic perspectives for inflammatory bone loss.

PTPN2 regulates bacterial clearance in a mouse model of enteropathogenic and enterohemorrhagic E. coli infection

Macrophages intimately interact with intestinal epithelial cells, but the consequences of defective macrophage-epithelial cell interactions for protection against enteric pathogens are poorly understood. Here, we show that in mice with a deletion in protein tyrosine phosphatase nonreceptor type 2 (PTPN2) in macrophages, infection with Citrobacter rodentium, a model of enteropathogenic and enterohemorrhagic E. coli infection in humans, promoted a strong type 1/IL-22-driven immune response, culminating in accelerated disease but also faster clearance of the pathogen. In contrast, deletion of PTPN2 specifically in epithelial cells rendered the epithelium unable to upregulate antimicrobial peptides and consequently resulted in a failure to eliminate the infection. The ability of PTPN2-deficient macrophages to induce faster recovery from C. rodentium was dependent on macrophage-intrinsic IL-22 production, which was highly increased in macrophages deficient in PTPN2. Our findings demonstrate the importance of macrophage-mediated factors, and especially macrophage-derived IL-22, for the induction of protective immune responses in the intestinal epithelium, and show that normal PTPN2 expression in the epithelium is crucial to allow for protection against enterohemorrhagic E. coli and other intestinal pathogens.

C-type lectin receptors in antifungal immunity: Current knowledge and future developments

C-type lectin receptors (CLRs) constitute a category of innate immune receptors that play an essential role in the antifungal immune response. For over two decades, scientists have uncovered what are the fungal ligands recognized by CLRs and how these receptors initiate the immune response. Such studies have allowed the identification of genetic polymorphisms in genes encoding for CLRs or for proteins involved in the signalisation cascade they trigger. Nevertheless, our understanding of how these receptors functions and the full extent of their function during the antifungal immune response is still at its infancy. In this review, we summarize some of the main findings about CLRs in antifungal immunity and discuss what the future might hold for the field.

PLK1 protects intestinal barrier function in sepsis: A translational research

BACKGROUND

Sepsis and its related complications are very challenging in the intensive care unit, among which intestinal barrier injury is a general manifestation. Polo-like kinase 1 (PLK1) is widely studied in cancer, while its role in sepsis is poorly understood. In this study, the efficiency of PLK1 as a marker of intestinal barrier function as well as a predictor of mortality in sepsis was evaluated.

METHODS

The level of serum PLK1 was measured in septic patients (n = 51) and controls (n = 20); subsequently, its correlation with serum diamine oxidase (DAO), d-lactate, and endotoxin levels and its ability topredict mortality were analysed. The survival rate and barrier injury degree were also assessed in septic mice.

RESULTS

Serum PLK1 levels were elevated in septic patients, were negatively correlated with serum DAO, d-lactate, and endotoxin levels, and had a high predictive value for 28-day mortality in patients. The serum PLK1 level in non-survivors was lower. The expression of PLK1 in the intestine was decreased in septic mice, and overexpression or inhibition of PLK1 alleviated or aggravated intestinal barrier injury, respectively, as evaluated by Chiu's score, serum levels of DAO and d-lactate, and expression of tight junction proteins. Overexpressing PLK1 also decreased the 72-hour death rate of septic mice. Further study also revealed the negative correlation of PLK1 and IL-6 in patients, and increasing or interfering with PLK1 expression reduced or increased the serum IL-6 level in mice.

CONCLUSIONS

PLK1 plays a critical role in intestinal barrier function during sepsis, providing a novel perspective for sepsis therapy in the clinic.

Exploration of the potential mechanism of Baicalin for hepatic fibrosis based on network pharmacology, gut microbiota, and experimental validation

Baicalin (BA) is among the most effective and abundant flavonoids extracted from Scutellaria baicalensis that may be utilized to treat diseases associated with hepatic fibrosis (HF). Through network pharmacology, gut microbiota, and experimental validation, this research intends to elucidate the multi-target mechanism of BA on HF. BA targets were screened using databases and literature. As a result, In the anti-HF mechanism, the BA and 191 HF-associated targets interact, with 9 specific targets indicating that the BA's anti-HF mechanism is closely linked to gut microbiota. Consequently, rat intestinal content samples were obtained and examined using 16S rRNA sequencing. In the BA-treated group, the gut microbiota was positively regulated at the phylum,and genus levels, with Lactobacillus performing significantly. The study concluded that BA has a multi-targeted anti-HF effect and has changed the gut microbial ecosystem.

The role of gut microbiota in liver regeneration

The liver has unique regeneration potential, which ensures the continuous dependence of the human body on hepatic functions. As the composition and function of gut microbiota has been gradually elucidated, the vital role of gut microbiota in liver regeneration through gut-liver axis has recently been accepted. In the process of liver regeneration, gut microbiota composition is changed. Moreover, gut microbiota can contribute to the regulation of the liver immune microenvironment, thereby modulating the release of inflammatory factors including IL-6, TNF-α, HGF, IFN-γ and TGF-β, which involve in different phases of liver regeneration. And previous research have demonstrated that through enterohepatic circulation, bile acids (BAs), lipopolysaccharide, short-chain fatty acids and other metabolites of gut microbiota associate with liver and may promote liver regeneration through various pathways. In this perspective, by summarizing gut microbiota-derived signaling pathways that promote liver regeneration, we unveil the role of gut microbiota in liver regeneration and provide feasible strategies to promote liver regeneration by altering gut microbiota composition.

Gut microbiota-dependent adaptor molecule recruits DNA methyltransferase to the TLR4 gene in colonic epithelial cells to suppress inflammatory reactions

The intestine is inhabited by a large number of commensal bacteria that are immunologically non-self, potentially causing inflammation. However, in a healthy intestine, inflammation is strictly controlled at low levels to maintain homeostasis. We previously reported that the gut microbiota induce DNA methylation of the gene encoding Toll-like receptor (TLR) 4, a pattern recognition receptor that recognizes lipopolysaccharides of gram-negative bacteria, in colonic epithelial cells, suggesting its role in controlling intestinal inflammation. However, there remains a question of how gut microbiota cause methylation of only specific genes including TLR4, despite the fact that DNA methyltransferase (DNMT) is common to all genes targeted for methylation. Here, we identified RBM14 as an adaptor molecule that recruits DNMT to the TLR4 gene. RBM14 was shown to bind DNMT3 and be expressed at significantly higher levels in an intestinal epithelial cell (IEC) line with hypermethylated TLR4 gene than in an IEC line with hypomethylated TLR4 gene. In addition, RBM14 interacted with DNA regions of the TLR4 gene, and knockdown of RBM14 suppressed DNA methylation of the TLR4 gene in IECs. Furthermore, RBM14 expression was higher in colonic epithelial cells of conventional mice than in those of germ-free mice. Collectively, these results indicate that the gut microbiota induce methylation of the TLR4 gene in colonic epithelial cells by upregulating RBM14, which can recruit DNMT3 to the gene. The regulation of adaptor molecules such as RBM14, which bind to specific target genes and recruit DNMT, can explain, at least in part, how gut microbiota contribute to the maintenance of intestinal homeostasis through epigenetic control of specific gene expression in IECs.

Deeper insight into the role of IL-17 in the relationship beween hypertension and intestinal physiology

With the incidence of hypertension increasing worldwide, more and more the mechanisms of hypertension from the perspective of immunity have found. Intestinal microbiota as well as its metabolites relationship with hypertension has attracted great attention from both clinicians and investigators. However, the associations of hypertension with lesions of a large number of immune factors including IL-17, MCP-1, IL-6, TGF-β, IL-10 and others have not been fully characterized. In this review, after introducing the immune factors as the most potent anti/pro-hypertension agents known, we provide detailed descriptions of the IL-17 involved in the pathology of hypertension, pointing out the underlying mechanisms and suggesting the clinical indications.

Context-Dependent Regulation of Type17 Immunity by Microbiota at the Intestinal Barrier

T-helper-17 (Th17) cells and related IL-17-producing (type17) lymphocytes are abundant at the epithelial barrier. In response to bacterial and fungal infection, the signature cytokines IL-17A/F and IL-22 mediate the antimicrobial immune response and contribute to wound healing of injured tissues. Despite their protective function, type17 lymphocytes are also responsible for various chronic inflammatory disorders, including inflammatory bowel disease (IBD) and colitis associated cancer (CAC). A deeper understanding of type17 regulatory mechanisms could ultimately lead to the discovery of therapeutic strategies for the treatment of chronic inflammatory disorders and the prevention of cancer. In this review, we discuss the current understanding of the development and function of type17 immune cells at the intestinal barrier, focusing on the impact of microbiota-immune interactions on intestinal barrier homeostasis and disease etiology.

Antifungal immunity mediated by C-type lectin receptors may be a novel target in immunotherapy for urothelial bladder cancer

Immunotherapies, such as immune-checkpoint blockade and adoptive T-cell therapy, offer novel treatment options with good efficacy for patients with urothelial bladder cancer. However, heterogeneity and therapeutic resistance have limited the use of immunotherapy. Further research into immune-regulatory mechanisms in bladder cancer is urgently required. Emerging evidence demonstrates that the commensal microbiota and its interactions with host immunity play pivotal roles in a variety of physiological and pathological processes, including in cancer. The gut microbiota has been identified as a potentially effective target of treatment that can be synergized with immunotherapy. The urothelial tract is also a key site for multiple microbes, although the immune-regulatory role of the urinary microbiome in the process of carcinogenesis of bladder cancer remains to be elucidated. We performed a comprehensive analysis of the expression and biological functions of C-type lectin receptors (CLRs), which have been recognized as innate pathogen-associated receptors for fungal microbiota, in bladder cancer. In line with previous research on fungal colonization of the urothelial tract, we found that CLRs, including Dectin-1, Dectin-2, Dectin-3, and macrophage-inducible Ca²⁺-dependent lectin receptor (Mincle), had a significant association with immune infiltration in bladder cancer. Multiple innate and adaptive pathways are positively correlated with the upregulation of CLRs. In addition, we found a significant correlation between the expression of CLRs and a range of immune-checkpoint proteins in bladder cancer. Based on previous studies and our findings, we hypothesize that the urinary mycobiome plays a key role in the pathogenesis of bladder cancer and call for more research on CLR-mediated anti-fungal immunity against bladder cancer as a novel target for immunotherapy in urothelial bladder cancer.

Multi-omics analyses of airway host-microbe interactions in chronic obstructive pulmonary disease identify potential therapeutic interventions

The mechanistic role of the airway microbiome in chronic obstructive pulmonary disease (COPD) remains largely unexplored. We present a landscape of airway microbe-host interactions in COPD through an in-depth profiling of the sputum metagenome, metabolome, host transcriptome and proteome from 99 patients with COPD and 36 healthy individuals in China. Multi-omics data were integrated using sequential mediation analysis, to assess in silico associations of the microbiome with two primary COPD inflammatory endotypes, neutrophilic or eosinophilic inflammation, mediated through microbial metabolic interaction with host gene expression. Hypotheses of microbiome-metabolite-host interaction were identified by leveraging microbial genetic information and established metabolite-human gene pairs. A prominent hypothesis for neutrophil-predominant COPD was altered tryptophan metabolism in airway lactobacilli associated with reduced indole-3-acetic acid (IAA), which was in turn linked to perturbed host interleukin-22 signalling and epithelial cell apoptosis pathways. In vivo and in vitro studies showed that airway microbiome-derived IAA mitigates neutrophilic inflammation, apoptosis, emphysema and lung function decline, via macrophage-epithelial cell cross-talk mediated by interleukin-22. Intranasal inoculation of two airway lactobacilli restored IAA and recapitulated its protective effects in mice. These findings provide the rationale for therapeutically targeting microbe-host interaction in COPD.

The gut-liver axis in immune remodeling of hepatic cirrhosis

In healthy settings, the gut-liver axis allows host-microbiota communications and mediates immune homeostasis through bidirectional regulation. Meanwhile, in diseases, gut dysbiosis, combined with an impaired intestinal barrier, introduces pathogens and their toxic metabolites into the system, causing massive immune alternations in the liver and other extrahepatic organs. Accumulating evidence suggests that these immune changes are associated with the progression of many liver diseases, especially hepatic cirrhosis. Pathogen-associated molecular patterns that originated from gut microbes directly stimulate hepatocytes and liver immune cells through different pattern recognition receptors, a process further facilitated by damage-associated molecular patterns released from injured hepatocytes. Hepatic stellate cells, along with other immune cells, contribute to this proinflammatory and profibrogenic transformation. Moreover, cirrhosis-associated immune dysfunction, an imbalanced immune status characterized by systemic inflammation and immune deficiency, is linked to gut dysbiosis. Though the systemic inflammation hypothesis starts to link gut dysbiosis to decompensated cirrhosis from a clinical perspective, a clearer demonstration is still needed for the role of the gut-liver-immune axis in cirrhosis progression. This review discusses the different immune states of the gut-liver axis in both healthy and cirrhotic settings and, more importantly, summarizes the current evidence about how microbiota-derived immune remodeling contributes to the progression of hepatic cirrhosis via the gut-liver axis.

Long-term antibiotic exposure promotes mortality after systemic fungal infection by driving lymphocyte dysfunction and systemic escape of commensal bacteria

Antibiotics are a modifiable iatrogenic risk factor for the most common human nosocomial fungal infection, invasive candidiasis, yet the underlying mechanisms remain elusive. We found that antibiotics enhanced the susceptibility to murine invasive candidiasis due to impaired lymphocyte-dependent IL-17A- and GM-CSF-mediated antifungal immunity within the gut. This led to non-inflammatory bacterial escape and systemic bacterial co-infection, which could be ameliorated by IL-17A or GM-CSF immunotherapy. Vancomycin alone similarly enhanced the susceptibility to invasive fungal infection and systemic bacterial co-infection. Mechanistically, vancomycin reduced the frequency of gut Th17 cells associated with impaired proliferation and RORγt expression. Vancomycin's effects on Th17 cells were indirect, manifesting only in vivo in the presence of dysbiosis. In humans, antibiotics were associated with an increased risk of invasive candidiasis and death after invasive candidiasis. Our work highlights the importance of antibiotic stewardship in protecting vulnerable patients from life-threatening infections and provides mechanistic insights into a controllable iatrogenic risk factor for invasive candidiasis.

Lactobacillus improves the effects of prednisone on autoimmune hepatitis via gut microbiota-mediated follicular helper T cells

Background

Autoimmune hepatitis (AIH) is a chronic, immune-mediated liver dysfunction. The gut microbiota and T follicular helper (Tfh) cells play critical roles in the immunopathogenesis and progression of AIH. We aimed to investigate the effect of gut microbiota combined with prednisone therapy on Tfh cell response in AIH.

Methods

Samples from AIH patients and mouse model of experimental autoimmune hepatitis (EAH) were analyzed using real-time quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, western blotting, flow cytometry, and hematoxylin–eosin staining to determine the role of gut microbiota on AIH.

Results

Lactobacillus significantly increased the levels of Bacteroides fragilis, Clostridium, Clostridium leptum, Bifidobacterium, and Lactobacillus and significantly enhanced the suppressive effects of prednisone on the levels of AIH clinical indexes in AIH patients. Lactobacillus exerts the same prptective effects as prednisone in EAH mice and enhanced the effects of prednisone. Lactobacillus also reinforced the inhibitory effects of prednisone on the levels of serum IL-21 and the proportions of Tfh cells in peripheral blood mononuclear cells. Mechanistically, prednisone and Lactobacillus regulated Tfh cell response in EAH mice in an MyD88/NF-κB pathway-dependent manner.

Conclusion

Our results suggested a therapeutic potential of Lactobacillus in the prednisone-combined treatment of AIH.