Toll-Like Receptor 7 Agonist-Induced Dermatitis Causes Severe Dextran Sulfate Sodium Colitis by Altering the Gut Microbiome and Immune Cells

Fecal microbiota transplantation for the treatment of chronic inflammatory skin diseases

The regulation of immune functions and the maintenance of homeostasis in the internal environment are both integral to human gut microbiota (GM). If GM is disturbed, it can result in a range of autoimmune diseases, including chronic inflammatory skin conditions. Chronic inflammatory skin diseases driven by T or B-cell-mediated immune reactions are complex, including the most prevalent diseases and some rare diseases. Expanding knowledge of GM dysbiosis in chronic inflammatory skin diseases has emerged. The GM has some causal roles in the pathogenesis of these skin conditions. Targeting microbiota treatment, particularly fecal microbiota transplantation (FMT), is considered to be a promising strategy. FMT was commonly used in intestinal diseases by reshaping and balancing GM, serving as a reasonable administration in these skin inflammatory diseases. This paper summarizes the existing knowledge of GM dysbiosis in chronic inflammatory skin diseases and the research data on FMT treatment for such conditions.

Short-chain fatty acids ameliorate imiquimod-induced skin thickening and IL-17 levels and alter gut microbiota in mice: a metagenomic association analysis

Short-chain fatty acids (SCFAs) have been proposed to have anti-inflammatory effects and improve immune homeostasis. We aimed to examine the effects of SCFAs on skin phenotype, systemic inflammation, and gut microbiota in mice with psoriasis-like inflammation. Imiquimod (IMQ)-treated C57BL/6 mice served as the study model. We conducted a metagenomic association study of IMQ-mice treated with SCFAs or anti-IL-17 antibody using whole-genome shotgun sequencing. The associations among SCFA supplements, skin thickness, circulating inflammatory profiles, and fecal microbiota profiles were investigated. The microbiome study was performed using pipelines for phylogenetic analysis, functional gene analysis, and pathway analysis. In IMQ-treated mice, there were increases in skin thickness and splenic weight, as well as unique fecal microbial profiles. SCFAs ameliorated IMQ-induced skin thickening, splenic weight gain, and serum IL-17F levels, with results that were comparable with those receiving anti-IL-17 treatment. IMQ-treated mice receiving SCFAs had greater microbial diversity than mice treated with IMQ alone. SCFAs and anti-IL17 treatment were associated with alteration of gut microbiota, with increased prevalences of Oscillospiraceae and Lachnopiraceae and decreased prevalences of Muribaculaceae and Bacteroides, which have been predicted to be associated with increased glycan degradation, phenylalanine metabolism, and xylene degradation. SCFAs may mitigate IMQ-induced skin thickening and IL-17F levels and alter fecal microbiota profiles in IMQ-treated mice.

Advances in psoriasis and gut microorganisms with co-metabolites

This review summarizes the potential role of gut microbes and their metabolites as novel mediators of psoriasis, including their composition and function in disease pathogenesis, progression, and management. Gut microbiota network analysis, colony construction, and in vivo large-scale interaction experiments showed that different degrees of damage and repair in psoriasis, both in animals and humans, involve cross-border homeostasis of the microbial community. Which gut microbiota interactions are present in psoriasis and how they collaborate with immune cells and influence psoriasis development via the gut-skin axis remain incompletely elucidated. In this article, we review the latest information on the unique patterns of gut microbiota and co-metabolites involved in the pathogenesis of psoriasis and attempt to explore microbial-based therapeutic targets derived from mono-and polymicrobial probiotics, fecal microbiota transplantation, pharmacomicrobiomics, and dietary interventions as diagnostic or therapeutic approaches promising to provide new options and long-term management for psoriasis.

Potential roles of inflammasomes in the pathophysiology of Psoriasis: A comprehensive review

Psoriasis is an inflammatory skin disease whose pathophysiology is attributed to both innate and adaptive immune cells and molecules. Despite the crucial roles of the immune system in psoriasis, it cannot be categorized as an autoimmune disease because of the lack of main signs of autoimmunity, such as specific antibodies, well-defined antigens, and autoimmune genetic risk factors. The presence of some cellular and molecular properties, such as the presence of neutrophils in skin lesions and the activation of the innate immune system, attributes psoriasis to a group of diseases called autoinflammatory disorders. Autoinflammatory diseases refer to a group of inherited disorders whose main manifestations are recurrent fever, a high level of acute-phase reactant, and a tendency for inflammation of the skin, joints, and other organs like the nervous system. In most autoinflammatory disorders, it has been seen that complexes of the high-molecular-weight protein named inflammasomes have significant roles. The inflammasome complex usually is formed and activated in the stimulated immune cell cytoplasm, and its activation consequently leads to inflammatory events such as producing of active caspase-1, mature interleukin-1β (IL-1β), and IL-18 and can cause an inflammatory programmed cell death called pyroptosis. Since the identification of inflammasomes, it has been shown that there are close links between them and hereditary and acquired autoinflammatory diseases like psoriasis. In this review, we aim to focus on well-defined inflammasome and their role in the pathophysiology of psoriasis.

The gut microbiota-induced kynurenic acid recruits GPR35-positive macrophages to promote experimental encephalitis

The intricate interplay between gut microbes and the onset of experimental autoimmune encephalomyelitis (EAE) remains poorly understood. Here, we uncover remarkable similarities between CD4+ T cells in the spinal cord and their counterparts in the small intestine. Furthermore, we unveil a synergistic relationship between the microbiota, particularly enriched with the tryptophan metabolism gene EC:1.13.11.11, and intestinal cells. This symbiotic collaboration results in the biosynthesis of kynurenic acid (KYNA), which modulates the recruitment and aggregation of GPR35-positive macrophages. Subsequently, a robust T helper 17 (Th17) immune response is activated, ultimately triggering the onset of EAE. Conversely, modulating the KYNA-mediated GPR35 signaling in Cx3cr1+ macrophages leads to a remarkable amelioration of EAE. These findings shed light on the crucial role of microbial-derived tryptophan metabolites in regulating immune responses within extraintestinal tissues.

Insights into Nutritional Strategies in Psoriasis

Psoriasis, an autoimmune chronic inflammatory skin condition, has a high incidence in the general population, reaching 2-4%. Its pathogenesis involves an interplay of genetic factors, immune disturbances, and environmental factors. Within the environmental factors that aid the appearance of this autoimmune skin disease, the Western lifestyle and overall diet play important roles in the steady growth in psoriasis prevalence. Furthermore, psoriasis is associated with comorbidities such as psoriatic arthritis, cardiovascular disease, metabolic syndrome, and obesity. Accumulating evidence suggests that obesity is an important risk factor for psoriasis. Moreover, obesity aggravates established psoriasis, and a reduction in the body mass index can improve the clinical outcomes of psoriasis and increase the efficacy of standard psoriasis therapies. The possible connection between this autoimmune disease and obesity relies on the fact that white adipose tissue is an essential endocrine organ that secretes an array of immune mediators and inflammatory and metabolic factors with pro-inflammatory action. Thus, immune-mediated mechanisms in both psoriasis and obesity conditions are common factors. This paper describes the factors that link obesity with skin autoimmune disease and highlights the importance of the stimulatory or regulatory effects of nutrients and food in psoriasis and the possible improvement of psoriasis through nutritional strategies.

TLR7/TLR8 activation and susceptibility genes synergize to breach gut barrier in a mouse model of lupus

Background

Mounting evidence suggests that increased gut permeability, or leaky gut, and the resulting translocation of pathobionts or their metabolites contributes to the pathogenesis of Systemic Lupus Erythematosus. However, the mechanisms underlying the induction of gut leakage remain unclear. In this study, we examined the effect of a treatment with a TLR7/8 agonist in the B6.Sle1.Sle2.Sle3 triple congenic (TC) mouse, a spontaneous mouse model of lupus without gut leakage.

Materials and methods

Lupus-prone mice (TC), TC.Rag1-/- mice that lack B and T cells, and congenic B6 healthy controls were treated with R848. Gut barrier integrity was assessed by measuring FITC-dextran in the serum following oral gavage. Claudin-1 and PECAM1 expression as well as the extent of CD45+ immune cells, B220+ B cells, CD3+ T cells and CD11b+ myeloid cells were measured in the ileum by immunofluorescence. NKp46+ cells were measured in the ileum and colon by immunofluorescence. Immune cells in the ileum were also analyzed by flow cytometry.

Results

R848 decreased gut barrier integrity in TC but not in congenic control B6 mice. Immunofluorescence staining of the ileum showed a reduced expression of the tight junction protein Claudin-1, endothelial cell tight junction PECAM1, as well as an increased infiltration of immune cells, including B cells and CD11b+ cells, in R848-treated TC as compared to untreated control mice. However, NKp46+ cells which play critical role in maintaining gut barrier integrity, had a lower frequency in treated TC mice. Flow cytometry showed an increased frequency of plasma cells, dendritic cells and macrophages along with a decreased frequency of NK cells in R848 treated TC mice lamina propria. In addition, we showed that the R848 treatment did not induce gut leakage in TC.Rag1-/- mice that lack mature T and B cells.

Conclusions

These results demonstrate that TLR7/8 activation induces a leaky gut in lupus-prone mice, which is mediated by adaptive immune responses. TLR7/8 activation is however not sufficient to breach gut barrier integrity in non-autoimmune mice.

The potential mechanism of qinghua quyu jianpi decoction in the treatment of ulcerative colitis based on network pharmacology and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Ulcerative colitis (UC) is a chronic and recurrent inflammation of the gastrointestinal tract. Following the idea of herbal property and compatibility, a traditional Chinese medicine (TCM) formula consists of a number of TCM herbs. Qinghua Quyu Jianpi Decoction (QQJD) has been clinically proven to be effective in treating UC, however, its therapeutic mechanism has not been fully elucidated.

AIM OF STUDY

Here, we used network pharmacology analysis and ultra-performance liquid chromatography-tandem mass spectrometry to predict the mechanism of action of QQJD, and then validated our predictions through in vivo and in vitro experiments.

MATERIALS AND METHODS

First, based on a number of datasets, relationship network diagrams between QQJD and UC were created. The target network for the QQJD-UC intersection genes was then built, and KEGG analysis was carried out to identify a potential pharmacological mechanism. Finally, the results of the previous prediction were validated in dextran sulfate sodium salt (DSS) induced UC mice and a cellular inflammatory model.

RESULTS

Network pharmacology results suggested that QQJD may play a role in repairing intestinal mucosa by activating Wnt pathway. In vivo experiments have shown that QQJD can significantly reduce weight loss, disease activity index (DAI) score, improve colon length, and effectively repair the tissue morphology of UC mice. In addition, we also found that QQJD can activate the Wnt pathway to promote epithelial cell renewal, reduce apoptosis, and repair the mucosal barrier. To further understand how QQJD promotes cell proliferation in DSS-induced Caco-2 cells, we performed a study in vitro experiment. We were surprised to find that QQJD activated the Wnt pathway by inducing nuclear translocation of β-catenin, accelerating the cell cycle and promoting cell proliferation in vitro.

CONCLUSION

Taken together, network pharmacology and experiments showed that QQJD achieves mucosal healing and restores the colonic epithelium barrier by activating Wnt/β-catenin signaling, regulating cell cycle progression, and promoting the proliferation of epithelial cells.

Fecal microbiota from MRL/lpr mice exacerbates pristane-induced lupus

BACKGROUND

The roles of gut microbiota in the pathogenesis of SLE have been receiving much attention during recent years. However, it remains unknown how fecal microbiota transplantation (FMT) and microbial metabolites affect immune responses and lupus progression.

METHODS

We transferred fecal microbiota from MRL/lpr (Lpr) mice and MRL/Mpj (Mpj) mice or PBS to pristane-induced lupus mice and observed disease development. We also screened gut microbiota and metabolite spectrums of pristane-induced lupus mice with FMT via 16S rRNA sequencing, metagenomic sequencing, and metabolomics, followed by correlation analysis.

RESULTS

FMT from MRL/lpr mice promoted the pathogenesis of pristane-induced lupus and affected immune cell profiles in the intestine, particularly the plasma cells. The structure and composition of microbial communities in the gut of the FMT-Lpr mice were different from those of the FMT-Mpj mice and FMT-PBS mice. The abundances of specific microbes such as prevotella taxa were predominantly elevated in the gut microbiome of the FMT-Lpr mice, which were positively associated with functional pathways such as cyanoamino acid metabolism. Differential metabolites such as valine and L-isoleucine were identified with varied abundances among the three groups. The abundance alterations of the prevotella taxa may affect the phenotypic changes such as proteinuria levels in the pristane-induced lupus mice.

CONCLUSION

These findings further confirm that gut microbiota play an important role in the pathogenesis of lupus. Thus, altering the gut microbiome may provide a novel way to treat lupus.

Moxibustion improves experimental colitis in rats with Crohn's disease by regulating bile acid enterohepatic circulation and intestinal farnesoid X receptor

OBJECTIVE

This study was conducted to explore the mechanism of intestinal inflammation and barrier repair in Crohn's disease (CD) regulated by moxibustion through bile acid (BA) enterohepatic circulation and intestinal farnesoid X receptor (FXR).

METHODS

Sprague-Dawley rats were randomly divided into control group, CD model group, mild moxibustion group and herb-partitioned moxibustion group. CD model rats induced by 2,4,6-trinitrobenzene sulfonic acid were treated with mild moxibustion or herb-partitioned moxibustion at Tianshu (ST25) and Qihai (CV6). The changes in CD symptoms were rated according to the disease activity index score, the serum and colon tissues of rats were collected, and the pathological changes in colon tissues were observed via histopathology. Western blot, immunohistochemistry (IHC) and immunofluorescence were used to evaluate the improvement of moxibustion on intestinal inflammation and mucosal barrier in CD by the BA-FXR pathway.

RESULTS

Mild moxibustion and herb-partitioned moxibustion improved the symptoms of CD, inhibited inflammation and repaired mucosal damage to the colon in CD rats. Meanwhile, moxibustion could improve the abnormal expression of BA in the colon, liver and serum, downregulate the expression of interferon-γ and upregulate the expression of FXR mRNA, and inhibit Toll-like receptor 4 (TLR4) and myeloid differentiation factor 88 (MyD88) mRNA. The IHC results showed that moxibustion could upregulate the expression of FXR and mucin2 and inhibit TLR4 expression. Western blot showed that moxibustion inhibited the protein expression of TLR4 and MyD88 and upregulated the expression of FXR. Immunofluorescence image analysis showed that moxibustion increased the colocalization sites and intensity of FXR with TLR4 or nuclear factor-κB p65. In particular, herb-partitioned moxibustion has more advantages in improving BA and upregulating FXR and TLR4 in the colon.

CONCLUSION

Mild moxibustion and herb-partitioned moxibustion can improve CD by regulating the enterohepatic circulation stability of BA, activating colonic FXR, regulating the TLR4/MyD88 pathway, inhibiting intestinal inflammation and repairing the intestinal mucosal barrier. Herb-partitioned moxibustion seems to have more advantages in regulating BA enterohepatic circulation and FXR activation. Please cite this article as: Shen JC, Qi Q, Han D, Lu Y, Huang R, Zhu Y, Zhang LS, Qin XD, Zhang F, Wu HG, Liu HR. Moxibustion improves experimental colitis in rats with Crohn's disease by regulating bile acid enterohepatic circulation and intestinal farnesoid X receptor. J Integr Med. 2023.

Immunological consequences of microbiome-based therapeutics

The complex network of microscopic organisms living on and within humans, collectively referred to as the microbiome, produce wide array of biologically active molecules that shape our health. Disruption of the microbiome is associated with susceptibility to a range of diseases such as cancer, diabetes, allergy, obesity, and infection. A new series of next-generation microbiome-based therapies are being developed to treat these diseases by transplanting bacteria or bacterial-derived byproducts into a diseased individual to reset the recipient's microbiome and restore health. Microbiome transplantation therapy is still in its early stages of being a routine treatment option and, with a few notable exceptions, has had limited success in clinical trials. In this review, we highlight the successes and challenges of implementing these therapies to treat disease with a focus on interactions between the immune system and microbiome-based therapeutics. The immune activation status of the microbiome transplant recipient prior to transplantation has an important role in supporting bacterial engraftment. Following engraftment, microbiome transplant derived signals can modulate immune function to ameliorate disease. As novel microbiome-based therapeutics are developed, consideration of how the transplants will interact with the immune system will be a key factor in determining whether the microbiome-based transplant elicits its intended therapeutic effect.

Loss of SLC26A3 Results in Colonic Mucosal Immune Dysregulation via Epithelial-Immune Cell Crosstalk

BACKGROUND & AIMS

Down-regulation of chloride transporter SLC26A3 or down-regulated in adenoma (DRA) in colonocytes has recently been linked to the pathogenesis of ulcerative colitis (UC). Because exaggerated immune responses are one of the hallmarks of UC, these current studies were undertaken to define the mechanisms by which loss of DRA relays signals to immune cells to increase susceptibility to inflammation.

METHODS

NanoString Immunology Panel, fluorescence assisted cell sorting, immunoblotting, immunofluorescence, and quantitative real-time polymerase chain reaction assays were used in wild-type and DRA knockout (KO) mice. Interleukin (IL)-33 blocking was used to determine specific changes in immune cells and co-housing/broad spectrum antibiotics administration, and ex vivo studies in colonoids were conducted to rule out the involvement of microbiota. Colonoid-derived monolayers from healthy and UC patient biopsies were analyzed for translatability.

RESULTS

There was a marked induction of Th2 (>2-fold), CD4⁺ Th2 cells (∼8-fold), RORγt⁺ Th17, and FOXP3⁺ regulatory T cells (Tregs). DRA KO colons also exhibited a robust induction of IL-33 (>8-fold). In vivo studies using blocking of IL-33 established that T2 immune dysregulation (alterations in ILC2, Th2, and GATA3⁺ iTregs) in response to loss of DRA was due to altered epithelial-immune cell crosstalk via IL-33.

CONCLUSIONS

Loss of DRA in colonocytes triggers the release of IL-33 to drive a type 2 immune response. These observations emphasize the critical importance of DRA in mucosal immune homeostasis and its implications in the pathogenesis of UC.

Lactobacillus johnsonii alleviates colitis by TLR1/2-STAT3 mediated CD206+ macrophagesIL-10 activation

Imbalance of gut microbiota homeostasis is related to the occurrence of ulcerative colitis (UC), and probiotics are thought to modulate immune microenvironment and repair barrier function. Here, in order to reveal the interaction between UC and gut microbiota, we screened a new probiotic strain by 16S rRNA sequencing from Dextran Sulfate Sodium (DSS)-induced colitis mice, and explored the mechanism and clinical relevance. Lactobacillus johnsonii (L. johnsonii), as a potential anti-inflammatory bacterium was decreased colonization in colitis mice. Gavage L. johnsonii could alleviate colitis by specifically increasing the proportion of intestinal macrophages and the secretion of Il-10 with macrophages depleted model and in Il10^-/- mice. We identified this subset of immune cells activated by L. johnsonii as CD206⁺ macrophages^IL-10. Mechanistically, L. johnsonii supplementation enhanced the mobilization of CD206⁺ macrophages^IL-10 through the activation of STAT3 in vivo and in vitro. In addition, we revealed that TLR1/2 was essential for the activation of STAT3 and the recognition of L. johnsonii by macrophages. Clinically, there was positive correlation between the abundance of L. johnsonii and the expression level of MRC1, IL10 and TLR1/2 in UC tissues. L. johnsonii could activate native macrophages into CD206⁺ macrophages and release IL-10 through TLR1/2-STAT3 pathway to relieve experimental colitis. L. johnsonii may serve as an immunomodulator and anti-inflammatory therapeutic target for UC.

Treatment of ulcerative colitis with Wu-Mei-Wan by inhibiting intestinal inflammatory response and repairing damaged intestinal mucosa

BACKGROUND

Wu-Mei-Wan (WMW), a traditional Chinese medicine, has been applied in the treatment of gastrointestinal diseases with long-term diarrhea and mucopurulent bloody stool as the main symptoms since ancient times. Studies have shown that WMW inhibits intestinal inflammation, repairs damaged intestinal mucosa, resists colon necrosis, and resists intestinal fibrosis. However, the specific mechanism of action is not yet clear.

OBJECTIVE

Ulcerative colitis (UC), an intestinal disease with intestinal inflammation and injury as the main pathological manifestations, is one of the high-risk factors for colon cancer. Inhibiting the inflammatory response and promoting colonic epithelial repair are critical to the treatment of UC. However, there is still a lack of remedies with satisfactory curative effects. In this study, the role of WMW in dextran sulfate sodium (DSS)-induced colitis in mice and its related mechanisms are discussed from two aspects: intestinal inflammation and tissue repair.

METHODS

DSS was used to induce colitis in mice and the therapeutic effect of WMW was analyzed by disease activity score, histopathological score, colon length measurement, serum cytokine detection, and flow cytometry. Macrophage activation and colonic stem cell proliferation were observed by immunohistochemistry. The expression of critical molecules in macrophage activation and colonic stem cell proliferation signaling pathways in colon tissue was detected with immunohistochemistry, immunofluorescence staining, RT-qPCR, and Western blot.

RESULTS

WMW could significantly alleviate DSS-induced colitis. We showed that WMW could reduce disease activity, reduce pathological scores, limit weight loss, inhibit colon shortening, inhibit inflammatory factor secretion, attenuate inflammatory response, and promote the repair of damaged colonic epithelium. WMW inhibited the activation of colonic macrophages, and its mechanism might be inhibiting the Notch/NF-κB/NLRP3 pathway; WMW promoted the proliferation of colonic stem cells, and its mechanism was associated with the regulation of the Hippo/YAP signaling pathway.

CONCLUSION

The results of this study suggested that WMW could treat UC via a mechanism that inhibited the intestinal inflammatory response and repaired damaged intestinal mucosa.

Gut dysbacteriosis attenuates resistance to Mycobacterium bovis infection by decreasing Cyclooxygenase 2 to inhibit endoplasmic reticulum stress

AbstractThe role of gut microbiota has been described as an important influencer of the immune system. Gut-lung axis is critical in the prevention of mycobacterium infection, but the specific mechanism by which dysbiosis affects tuberculosis have not been reported. In this study, we attempted to provide more information on how the gut-lung axis contributes to Mycobacterium bovis (M. bovis) infection. Mice pre-treated with broad-spectrum antibiotics cocktail (Abx) to induce gut dysbiosis. Interestingly, dysbiosis of microbes showed a significant increase in the bacterial burden in lungs, and inhibited the level of COX-2. After fecal transplantation, cyclooxygenase 2（COX-2） expression was restored and the inflammatory lesion in the lung was reduced. Further research found that the deficiency of COX-2 inhibited endoplasmic reticulum stress (ER-stress). This mechanism was completed by COX-2 interaction with BIP. Moreover, we found a positive feedback mechanism by which blocking ER-stress could reduce COX-2 levels via the NF-κB pathway. Taken together, we reveal for the first time gut dysbacteriosis exacerbates M. bovis disease by limiting COX-2 /ER-stress pathway. The finding strengthens the foundation of gut microbiota-targeted therapy for tuberculosis treatment.

Wu-Mei-Wan Ameliorates Murine Ulcerative Colitis by Regulating Macrophage Polarization

An increasing body of evidence shows that macrophages play an important role in the pathogenesis of ulcerative colitis (UC). Macrophage polarization and changes in related signaling pathways are reported to have a protective effect on intestinal inflammation. The well-known Chinese medicine Wumeiwan (WMW) has been used to treat diarrhea, one of the main symptoms of colitis, for more than 2,000 years. Increasing evidence shows that WMW can inhibit intestinal inflammation and repair damaged intestinal mucosa, but its effector mechanisms are unknown. Therefore, we studied the prophylactic effects of WMW in dextran sulfate sodium (DSS)-induced UC and its effects on macrophage mechanisms and polarization. The results show that colitis was significantly alleviated in mice in the WMW group, and the secretion and expression of pro-inflammatory factors TNF-α, IL-1, and IL-6 were inhibited in the serum and colonic tissues of mice with WMW-treated colitis, whereas anti-inflammatory factors IL-10, Arg-1, and TGF-β1 were increased. Subsequent studies found that WMW could inhibit M1 polarization and promote M2 polarization in colonic macrophages in DSS-induced colitis mice. Network pharmacology was used to predict potential targets and pathways, and further studies confirmed the related targets The results showed that WMW gradually inhibits the activation of the P38MAPK and NF-κB signaling pathways and further activates the STAT6 signaling pathway. In summary, WMW interferes with the p38MAPK, NF-κB and STAT6 signaling pathways to regulate M1/M2 polarization in macrophages, thereby protecting mice against DSS-induced colitis.

Gut and Cutaneous Microbiome Featuring Abundance of Lactobacillus reuteri Protected Against Psoriasis-Like Inflammation in Mice

Background

Psoriasis is a chronic autoinflammatory skin disease, and its aetiology remains incompletely understood. Recently, gut microbial dysbiosis is found to be tightly associated with psoriasis.

Objective

We sought to reveal the causal role of gut microbiota dysbiosis in psoriasis pathogenesis and investigate the protective effect of healthy commensal bacteria against imiquimod -induced psoriasis-like skin response.

Methods

By using fecal microbial transplantation (FMT), 16S rRNA gene-based taxonomic profiling and Lactobacillus supplement, we have assessed the effect of FMT from healthy individuals on psoriasis-like skin inflammation and associated immune disorders in imiquimod-induced psoriasis mice.

Results

Here, by using psoriasis mice humanized with the stools from healthy donors and psoriasis patients, the imiquimod-induced psoriasis in mice with psoriasis patient stool was found to be significantly aggravated as compared to the mice with healthy donor stools. Further analysis showed fecal microbiota of healthy individuals protected against Treg/Th17 imbalance in psoriasis. Moreover, we found the gut and skin microbiome in mice receipted with gut microbiota of healthy individuals (HD) differed from those of mice receipted with gut microbiota of psoriasis patients (PSD). 16S rRNA sequencing revealed that Lactobacillus reuteri was greatly enriched in fecal and cutaneous microbiome of HD mice as compared to PSD mice. Intriguingly, supplement with Lactobacillus reuteri was sufficient to increase the expression of anti-inflammatory gene IL-10, reduce Th17 cells counts and confer resistance to imiquimod-induced inflammation on the mice with gut microbiota dysbiosis.

Conclusion

Our results suggested that the gut microbiota dysbiosis is the potential causal factor for psoriasis and the gut microbiota may serve as promising therapy target for psoriasis patients.

Traditional herbal formula Wu-Mei-Wan alleviates TNBS-induced colitis in mice by inhibiting necroptosis through increasing RIPK3 O-GlcNAcylation

Background

Accumulating evidence indicated that necroptosis plays an essential role in the pathogenesis of inflammatory bowel disease (IBD). The O-linked β-N-acetylglucosaminylation (O-GlcNAcylation) of necroptotic signal molecule receptor-interacting serine-threonine kinase 3 (RIPK3) was reported to exert a protective effect in gut inflammation. Our recent study suggested traditional Chinese herbal formula Wu-Mei-Wan (WMW) as an effective prescription in mouse colitis. However, the potential mechanisms are not fully understood. Considering the crucial role of necroptosis in the pathogenesis of IBD, therefore, this study was designed to explain whether the anti-colitis effect of WMW is mediated by modulating necroptosis and its related mechanisms.

Methods

The protective effects of WMW on colitis have been determined by detecting colitis mice body weight, disease activity index (DAI), survival rate and colon length. Colonic inflammation was examined by inflammatory cells infiltration and local cytokines levels. After then, we measured the levels of necroptosis and O-GlcNAcylation. C O-immunoprecipitation experiments were used to address whether elevated O-GlcNAcylation can inhibit necroptotic signal transduction in the treatment of WMW. Finally, the key enzymes in O-GlcNAcylation: O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA) were examined and molecular docking analysis was used to determine effective natural compounds in the regulation on OGT and OGA activities.

Results

Our results showed that WMW significantly improved mice body weight, survival rate and colon length, decreased DAI in TNBS-induced colitis. WMW obviously alleviated colonic inflammatory responses with reduced macrophages, neutrophils infiltration and local IL-1β, IL-6, TNF-α and IFN-γ levels. It was found that WMW increased colonic O-GlcNAcylation level and inhibited the activation of RIPK1, RIPK3 and MLKL. Then, further experiments revealed that WMW enhanced OGT activity and suppressed OGA activity, thereby increasing RIPK3 O-GlcNAcylation and inhibiting the binding of RIPK3 and MLKL, which led to the inhibition of necroptosis. Additionally, docking analysis demonstrated that hesperidin, coptisine and ginsenoside Rb1 may exert a major role in the regulation on OGT and OGA activities by WMW.

Conclusion

Our work demonstrated that WMW can alleviate TNBS-induced colitis in mice by inhibiting necroptosis through increasing RIPK3 O-GlcNAcylation.

Effect of Cigarette Smoke on Gut Microbiota: State of Knowledge

Cigarette smoke is a representative source of toxic chemical exposures to humans, and the adverse consequences of cigarette smoking are mediated by its effect on both neuronal and immune-inflammatory systems. Cigarette smoking also is a major risk factor for intestinal disorders, such as Crohn's disease and peptic ulcer. On the other hand, cigarette smoking is protective against developing ulcerative colitis. The effects of cigarette smoking on intestinal disorders include changes in intestinal irrigation and microbiome, increases in permeability of the mucosa, and impaired mucosal immune responses. However, the underlying mechanism linking cigarette smoking with intestinal microbiota dysbiosis is largely unknown. In this communication, we first review the current knowledge about the mechanistic interaction between cigarette smoke and intestinal microbiota dysbiosis, which include the likely actions of nicotine, aldehydes, polycyclic aromatic hydrocarbons, heavy metals, volatile organic compounds and toxic gases, and then reveal the potential mechanisms of the lung-gut cross talk and skin-gut cross talk in regulating the balance of intestinal microbiota and the interrelation of intestinal microbiota dysbiosis and systemic disorders.

Abnormal composition of microbiota in the gut and skin of imiquimod-treated mice

Psoriasis is a chronic, inflammatory skin disease. Although the precise etiology of psoriasis remains unclear, gut-microbiota axis might play a role in the pathogenesis of the disease. Here we investigated whether the composition of microbiota in the intestine and skin is altered in the imiquimod (IMQ)-treated mouse model of psoriasis. Topical application of IMQ to back skin caused significant changes in the composition of microbiota in the intestine and skin of IMQ-treated mice compared to control mice. The LEfSe algorithm identified the species Staphylococcus lentus as potential skin microbial marker for IMQ group. Furthermore, there were correlations for several microbes between the intestine and skin, suggesting a role of skin-gut-microbiota in IMQ-treated mice. Levels of succinic acid and lactic acid in feces from IMQ-treated mice were significantly higher than control mice. Moreover, the predictive functional analysis of the microbiota in the intestine and skin showed that IMQ caused alterations in several KEGG pathways. In conclusion, the current data indicated that topical application with IMQ to skin alters the composition of the microbiota in the gut and skin of host. It is likely that skin-gut microbiota axis plays a role in pathogenesis of psoriasis.

Regulation of Tissue Immune Responses by Local Glucocorticoids at Epithelial Barriers and Their Impact on Interorgan Crosstalk

The anti-inflammatory role of extra-adrenal glucocorticoid (GC) synthesis at epithelial barriers is of increasing interest with regard to the search for alternatives to synthetic corticosteroids in the therapy of inflammatory disorders. Despite being very effective in many situations the use of synthetic corticosteroids is often controversial, as exemplified in the treatment of influenza patients and only recently in the current COVID-19 pandemic. Exploring the regulatory capacity of locally produced GCs in balancing immune responses in barrier tissues and in pathogenic disorders that lead to symptoms in multiple organs, could provide new perspectives for drug development. Intestine, skin and lung represent the first contact zones between potentially harmful pathogens or substances and the body, and are therefore important sites of immunoregulatory mechanisms. Here, we review the role of locally produced GCs in the regulation of type 2 immune responses, like asthma, atopic dermatitis and ulcerative colitis, as well as type 1 and type 3 infectious, inflammatory and autoimmune diseases, like influenza infection, psoriasis and Crohn’s disease. In particular, we focus on the role of locally produced GCs in the interorgan communication, referred to as gut-skin axis, gut-lung axis or lung-skin axis, all of which are interconnected in the pathogenic crosstalk atopic march.

Nicotinamide Mononucleotide Combined With Lactobacillus fermentum TKSN041 Reduces the Photoaging Damage in Murine Skin by Activating AMPK Signaling Pathway

Long-term exposure to UVB (280-320 nm) can cause oxidative skin damage, inflammatory injury, and skin cancer. Research on nicotinamide mononucleotide (NMN) and lactic acid bacteria (LAB) with regard to antioxidation, anti-inflammation, and prevention of other age-related diseases has received increasing attention. In the present study, the in vitro antioxidant analysis showed that NMN combined with Lactobacillus fermentum TKSN041 (L. fermentum TKSN041) has a high scavenging ability on hydroxyl (OH), 2, 2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) diammonium salt (ABTS) and 1, 1-diphenyl-2-picrylhydrazyl (DPPH), and it also possess a good total antioxidant capacity. The animal experimental results show that NMN combined with LAB maintained normal liver morphology of mice and reduced pathological damage to murine skin. NMN combined with LAB significantly increased the serum levels of total superoxide dismutase (T-SOD), catalase (CAT), and interleukin (IL)-10, but reduced the levels of malondialdehyde, advanced glycation end products, tumor necrosis factor (TNF)-α, and IL-6. NMN combined with LAB increased T-SOD, CAT, IL-10, Na⁺-K⁺-ATPase, and NAD⁺ levels in the skin, but reduced TNF-α level in the skin. NMN combined with LAB increased the mRNA expression levels of SOD1, CAT, glutathione (GSH), inhibitor of NF-κB (IκB-α), IL-10, AMP-activated protein kinase (AMPK), adaptor protein, phosphotyros ineinteraction, PH domain and leucine zipper containing 1 (APPL1), peroxisome proliferator-activated receptor γ co-activator-1α (PGC-1α), and forkhead transcription factor O (FOXO) in the skin and liver, but decreased the mRNA expression levels of nuclear factor (NF)-κBp65, TNF-α, IL-6, and rapamycin target protein (mTOR). NMN combined with LAB increased the protein expression levels of AMPK, IκB-α, SOD1, and CAT in the skin tissues and reduced protein expression of NF-κBp65. NMN combined with L. fermentum TKSN041 improved murine skin damage caused by UVB irradiation, and the protective mechanism may be related to activation of the AMPK signaling pathway. The results of this study are expected to provide a reference for preventing and the treating skin photoaging.

Anemoside B4 ameliorates TNBS-induced colitis through S100A9/MAPK/NF-κB signaling pathway

BACKGROUND

Despite the increased morbidity of ulcerative colitis (UC) in the developing countries, available treatments remain unsatisfactory. Therefore, it is urgent to discover more effective therapeutic strategies. Pulsatilla chinensis was widely used for the treatment of inflamed intestinal diseases including UC for thousands of years in China. Anemoside B4, the most abundant triterpenoid saponin isolated from P. chinensis, exerts anti-inflammatory and antioxidant effects and may be the most active compounds, which is responsible for the therapeutic effects. However, the mechanism how anemoside B4 executes its biological functions is still elusive.

METHODS

Here, we used the 2, 4, 6-trinitrobenzene sulfonic acid (TNBS)-induced colitis rat model to evaluate the therapeutic effect of anemoside B4. Blood samples of colitis rats were collected for hematology analysis. The inflammation-associated factors were investigated by enzyme-linked immunosorbent assay (ELISA). Cell proliferation and apoptosis was determined with EdU cell proliferation assay and TUNEL assay. The proteins regulated by anemoside B4 were identified by label-free quantitative proteomics. The significantly down-regulated proteins were verified by Western blotting analysis. mRNA expression was analyzed by quantitative real-time RT-PCR.

RESULTS

The results showed that anemoside B4 ameliorated TNBS-induced colitis symptoms, including tissue damage, inflammatory cell infiltration, and pro-inflammatory cytokine production, apoptosis and slowed proliferation in colon. Quantitative proteomic analyses discovered that 56 proteins were significantly altered by anemoside B4 in the TNBS-induced rats. These proteins mainly clustered in tricarboxylic acid (TCA) cycle and respiratory electron transport chain. Among the altered proteins, S100A9 is one of the most significantly down-regulated proteins and associated with NF-κB and MAPK signaling pathways in the pathogenesis of UC. Further experiments revealed that anemoside B4 suppressed the expression of S100A9 and its downstream genes including TLR4 and NF-κB in colon. In vitro, anemoside B4 could inhibit the NF-κB signaling pathway induced by recombinant S100A9 protein in human intestinal epithelial Caco-2 cells. Moreover, anemoside B4 inhibits neutrophils recruitment and activation in colon induced by TNBS.

CONCLUSIONS

Our results demonstrate that anemoside B4 prevents TNBS-induced colitis by inhibiting the NF-κB signaling pathway through deactivating S100A9, suggesting that anemoside B4 is a promising therapeutic candidate for colitis.

Investigating causality with fecal microbiota transplantation in rodents: applications, recommendations and pitfalls

In recent years, studies investigating the role of the gut microbiota in health and diseases have increased enormously - making it essential to deepen and question the research methodology employed. Fecal microbiota transplantation (FMT) in rodent studies (either from human or animal donors) allows us to better understand the causal role of the intestinal microbiota across multiple fields. However, this technique lacks standardization and requires careful experimental design in order to obtain optimal results. By comparing several studies in which rodents are the final recipients of FMT, we summarize the common practices employed. In this review, we document the limitations of this method and highlight different parameters to be considered while designing FMT Studies. Standardizing this method is challenging, as it differs according to the research topic, but avoiding common pitfalls is feasible. Several methodological questions remain unanswered to this day and we offer a discussion on issues to be explored in future studies.

Virus in the pathogenesis of inflammatory bowel disease: role of Toll-like receptor 7/8/3

The pathogenesis of inflammatory bowel disease (IBD) is influenced by immune system malfunction, particularly innate immune receptors such as toll-like receptors. Furthermore, it is critical to investigate the extremely close association between viruses and IBD incidence. Toll-like receptors (TLRs) 3, 5, and 7 are involved in antiviral immune responses. Finding a relationship between TLR-related virus and IBD is important not only for understanding the disease pathogenesis, but also for developing effective therapies. It has been shown that influenza is expressed more severely in patients with IBD who use immune system inhibitors, and the influenza vaccine is less effective in these patients. In dendritic cells, TLR7 and TLR8 regulate the production of interferons (IFNs) and inflammatory mediators. COVID-19 causes the production of IL-6, possibly due to the induction of TLR pathways. TLR activation by SARS-CoV-2 causes inflammation and IL-1 production, which induces the production of IL-6. Understanding TLR-associated viruses' molecular mechanisms can greatly help improve the quality of life of people with IBD. Therefore, the present study reviewed the role of TLR7, 8, and 3 in inflammatory bowel disease as well as their association with viral infections and evaluated different antagonists for the treatment of IBD.

Host-microbiota interactions in immune-mediated diseases

Host-microbiota interactions are fundamental for the development of the immune system. Drastic changes in modern environments and lifestyles have led to an imbalance of this evolutionarily ancient process, coinciding with a steep rise in immune-mediated diseases such as autoimmune, allergic and chronic inflammatory disorders. There is an urgent need to better understand these diseases in the context of mucosal and skin microbiota. This Review discusses the mechanisms of how the microbiota contributes to the predisposition, initiation and perpetuation of immune-mediated diseases in the context of a genetically prone host. It is timely owing to the wealth of new studies that recently contributed to this field, ranging from metagenomic studies in humans and mechanistic studies of host-microorganism interactions in gnotobiotic models and in vitro systems, to molecular mechanisms with broader implications across immune-mediated diseases. We focus on the general principles, such as breaches in immune tolerance and barriers, leading to the promotion of immune-mediated diseases by gut, oral and skin microbiota. Lastly, the therapeutic avenues that either target the microbiota, the barrier surfaces or the host immune system to restore tolerance and homeostasis will be explored.

Wu-Mei-Wan ameliorates chronic colitis-associated intestinal fibrosis through inhibiting fibroblast activation

ETHNOPHARMACOLOGICAL RELEVANCE

Wu-Mei-Wan (WMW), a classic traditional Chinese herb medicine, is one of the most important formulations to treat digestive diseases from ancient times to the present. Previous study showed that WMW has satisfactory curative effects on experimental colitis, which motivating the application of WMW on colitis-associated complications.

AIM OF THE STUDY

Intestinal fibrosis is usually considered to be a common complication of inflammatory bowel disease (IBD), particularly Crohn's disease (CD). Currently, no effective preventive measures or medical therapies are available for that. This work was designed to evaluate the effect and related mechanism of WMW on chronic colitis-associated intestinal fibrosis mice model.

MATERIALS AND METHODS

The chronic colitis-associated intestinal fibrosis mice model was established by weekly intrarectal injection of 2,4,6-trinitrobenzene sulfonic acid (TNBS). The mice survival rate, disease activity index (DAI), colon length and histological score were examined to assess the therapeutic effect of WMW. Masson's trichrome staining, hydroxyproline assay, immunohistochemical staining and western blot analysis were used to evaluate fibrosis level. Colon inflammation was determined by ELISA and immunofluorescence staining. Immunofluorescence staining was used to evaluate fibroblasts proliferation and epithelial to mesenchymal transition (EMT), and the expression of key molecules in fibrosis was analyzed by western blot.

RESULTS

Here we showed that WMW alleviates chronic colitis with improved survival rate, DAI, colon length and histological score. WMW inhibited the progression of intestinal fibrosis, decreased the expression of various fibrosis markers, such as α-SMA, collagen I, MMP-9 and fibronectin. In addition, WMW treatment reduced cytokines IL-6 and IFN-γ, and downregulated proinflammatory NF-κBp65 and STAT3 signaling pathways. Importantly, administration of WMW led to the inhibition of colon fibroblast proliferation and EMT, which are important mediators during fibrosis. Several key profibrotic pathways, including TGF-β/Smad and Wnt/β-catenin pathways, were downregulated by WMW treatment.

CONCLUSION

Our work demonstrated that WMW can prevent intestinal fibrosis and the mechanisms involved may be related to the inhibition of colon fibroblasts activation.

Friend or foe? Lactobacillus in the context of autoimmune disease

Over the last decade, the interplay between the gut microbiota, the consortium of intestinal microbes that colonizes intestinal mucosal barriers, and its host immune system has been increasingly better understood. Disruption of the delicate balance between beneficial and pathogenic commensals, known as dysbiosis, contributes to a variety of chronic immunologic and metabolic diseases. Complicating this paradigm are bacterial strains that can operate paradoxically both as instigators and attenuators of inflammatory responses, depending on host background. Here, we review the role of several strains in the genus Lactobacillus within the context of autoimmune and other chronic disorders with a predominant focus on L. reuteri. While strains within this species have been shown to provide immune health benefits, they have also been demonstrated to act as a pathobiont in autoimmune-prone hosts. Beneficial functions in healthy hosts include competing with pathogenic microbes, promoting regulatory T cell development, and protecting the integrity of the gut barrier. On the other hand, certain strains can also break through a dysfunctional gut barrier, colonize internal tissues such as the spleen or liver and promote inflammatory responses in host tissues that lead to autoimmune disease. This review summarizes the manifold roles that these commensals play in the context of health and disease.

The interaction of intestinal microbiota and innate lymphoid cells in health and disease throughout life

Immunity is shaped by commensal microbiota. From early life onwards, microbes colonize mucosal surfaces of the body and thereby trigger the establishment of immune homeostasis and defense mechanisms. Recent evidence reveals that the family of innate lymphoid cells (ILCs), which are mainly located in mucosal tissues, are essential in the maintenance of barrier functions as well as in the initiation of an appropriate immune response upon pathogenic infection. In this review, we summarize recent insights on the functional interaction of microbiota and ILCs at steady‐state and throughout life. Furthermore, we will discuss the interplay of ILCs and the microbiota in mucosal infections focusing on intestinal immunity.

Cystatin from Filarial Parasites Suppress the Clinical Symptoms and Pathology of Experimentally Induced Colitis in Mice by Inducing T-Regulatory Cells, B1-Cells, and Alternatively Activated Macrophages

Potential alternative therapeutic strategies for immune-mediated disorders are being increasingly recognized and are studied extensively. We previously reported the therapeutic potential of Brugia malayi derived recombinant cystatin (rBmaCys) in attenuating clinical symptoms of experimental colitis. The aim of this study was to elucidate the mechanisms involved in the rBmaCys-induced suppression of inflammation in the colon. Our results show that, the frequency of CD4⁺CD25⁺FoxP3⁺ regulatory T-cells was elevated in the colon and mesenteric lymph nodes. Similarly, the peritoneal macrophages recovered from the rBmaCys-treated colitis mice were alternatively activated and displayed reduced expression of TNF-α and IL-6. Another finding was significant increases in IgM⁺B1a-cells in the peritoneal cavity of mice following rBmaCys-treatment. These findings suggested that the regulatory cell network promoted by the rBmaCys in the colon and associated lymphoid tissues is important for its anti-inflammatory activity in the dextran sulfate sodium (DSS)-induced colitis mice.

Human IL-23R Cytokine-Binding Homology Region-Fc Fusion Protein Ameliorates Psoriasis via the Decrease of Systemic Th17 and ILC3 Cell Responses

Interleukin (IL)-23 is considered an effective therapeutic target for the treatment of psoriasis because of the crucial role of the IL-23/IL-17 axis in the pathogenesis of psoriasis, and it has recently been reported to be involved in ILC3 cell differentiation. In this study, we report that eukaryotically expressed rhIL23R-CHR/Fc, as an endogenous extracellular receptor analogue, could be a natural antagonist in an imiquimod (IMQ)-induced psoriasis-like mouse model, including the antagonizing effect of suppressed inflammation in the skin lesion, decreased production of pro-inflammatory cells, and reduced the expression of pro-inflammatory factors. The rhIL23R-CHR/Fc fusion protein inhibits both innate immune and adaptive immune-mediated inflammatory responses. These findings shed light on rhIL23R-CHR/Fc as a promising candidate therapy for the treatment of psoriasis.