IL-6 deficiency promotes colitis by recruiting Ly6Chi monocytes into inflamed colon tissues in a CCL2-CCR2-dependent manner

FGF1ΔHBS ameliorates DSS-induced ulcerative colitis by reducing neutrophil recruitment through the MAPK pathway

BACKGROUND AND PURPOSE

Inflammatory bowel diseases (IBDs) constitute chronic inflammatory disease of the gastrointestinal tract, with escalating global prevalence. There is a pressing demand for safe and effective treatments for IBDs. Fibroblast growth factor 1 (FGF1) variant FGF1ΔHBS, characterised by reduced mitogenic capacity, has shown promising therapeutic potential in various inflammatory conditions, including obesity and diabetic nephropathy. Hence, exploring the therapeutic impact of FGF1ΔHBS on colitis is warranted.

EXPERIMENTAL APPROACH

The protective role of FGF1ΔHBS was evaluated using a dextran sulphate sodium (DSS)-induced colitis model in mice. RNA-seq analysis was performed on colonic tissues. Inflammatory factor expression was examined by quantitative real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay. Flow cytometry and immunofluorescence staining were employed to confirm the inhibitory effect of FGF1ΔHBS on neutrophil recruitment. Western blotting was performed to explore the mitogen-activated protein kinase (MAPK) signalling pathway.

KEY RESULTS

FGF1ΔHBS significantly alleviated DSS-induced colitis, as indicated by reduced Disease Activity Index scores and less histological injury to the colon. Additionally, FGF1ΔHBS decreased the expression of pro-inflammatory factors. Mechanistically, FGF1ΔHBS inhibited neutrophil-associated chemokine expression in intestinal epithelial cells by suppressing the MAPK signalling pathway, thereby reducing neutrophil recruitment and attenuating neutrophil-mediated intestinal inflammation.

CONCLUSION AND IMPLICATIONS

FGF1ΔHBS protects against DSS-induced colitis in mice by inhibiting neutrophil recruitment through MAPK activity suppression, suggesting a potential therapeutic strategy for preventing IBDs.

Human umbilical cord mesenchymal stem cell-derived microvesicles alleviate pulmonary fibrosis by inhibiting monocyte‒macrophage migration through ERK1/2 signaling-mediated suppression of CCL2 expression

BACKGROUND

Pulmonary fibrosis (PF) is a disease with high morbidity and mortality rates, but effective treatment options are extremely limited. Mesenchymal stem cells (MSCs) and their derivatives show promise as potential therapeutics for PF. However, the underlying mechanisms responsible for these beneficial effects remain poorly understood. The objective of this study was to elucidate the specific mechanism through which microvesicles derived from human umbilical cord MSCs (MSC-MVs) alleviate PF.

METHODS

The effects of MSC-MVs on PF in bleomycin (BLM)-induced mice were assessed via histological staining, flow cytometry, and enzyme-linked immunosorbent assays (ELISAs). The potential therapeutic target was identified via RNA sequencing (RNA-seq) analysis, followed by validation via real-time quantitative polymerase chain reaction (RT‒qPCR), ELISAs, scratch testing, and western blotting (WB).

RESULTS

MSC-MVs significantly attenuated collagen fiber deposition and downregulated the expression of extracellular matrix components in the lungs of the BLM-induced mice. Moreover, this treatment substantially ameliorated lung inflammation by reducing the monocyte‒macrophage ratio and the TNF-α and IL-6 levels. Further analyses revealed that MSC-MVs inhibited the classic chemotactic CCL2/CCR2 axis of monocyte‒macrophages, leading to reduced recruitment of monocytes‒macrophages to the lungs, which decreased lung inflammation and prevented fibrotic progression. Both in vitro and in vivo findings demonstrated that MSC-MVs suppressed ERK1/2 phosphorylation followed by decreased CCL2 production to modulate monocyte-macrophage migration.

CONCLUSIONS

Our findings demonstrate that the protective effect of MSC-MVs against BLM-induced lung toxicity was achieved through the inhibition of the ERK1/2 signaling pathway, leading to the suppression of CCL2 expression and subsequent modulation of monocyte-macrophage migration, thereby establishing a theoretical basis for the effect of MSC-MVs in PF.

Umbilical Cord Mesenchymal Stem Cells Could Reduce Lung Damage Caused by H1N1 Influenza Virus Infection

Influenza A virus infection can cause acute respiratory distress syndrome (ARDS), and to date, viral pneumonia has been the main cause of ARDS. Bone marrow mesenchymal stem cells have shown promise for treating lung injury caused by avian influenza virus infection. At present, studies of the use of other stem cell types to treat human influenza virus-mediated lung damage are sparse. We assessed the use of umbilical cord mesenchymal stem cells (UC-MSCs) to treat damage from serious H1N1 influenza virus infections in cell and animal-based experiments. Maximum viral titers, inflammatory factor expression levels, differential expression of alveolar cell-related proteins, animal weight and survival rate, lung histopathology, and other indicators were evaluated. Compared with the control group, in cellular experiments, UC-MSCs could effectively inhibit H1N1 influenza viral replication and repair damaged host cells. In animal experiments, UC-MSCs reduced expression of pro-inflammatory cytokines, reduced entry of inflammatory cells into the lungs, alleviated lung inflammation, significantly reduced the extent of lung injury in mice, and improved lung histopathology, improving overall survival. A positive role of umbilical cord-derived mesenchymal stem cells in treating lung injury caused by H1N1 influenza virus infection that is worthy of clinical promotion has been demonstrated.

The role and therapeutic targeting of the CCL2/CCR2 signaling axis in inflammatory and fibrotic diseases

CCL2, a pivotal cytokine within the chemokine family, functions by binding to its receptor CCR2. The CCL2/CCR2 signaling pathway plays a crucial role in the development of fibrosis across multiple organ systems by modulating the recruitment and activation of immune cells, which in turn influences the progression of fibrotic diseases in the liver, intestines, pancreas, heart, lungs, kidneys, and other organs. This paper introduces the biological functions of CCL2 and CCR2, highlighting their similarities and differences concerning fibrotic disorders in various organ systems, and reviews recent progress in the diagnosis and treatment of clinical fibrotic diseases linked to the CCL2/CCR2 signaling pathway. Additionally, further in-depth research is needed to explore the clinical significance of the CCL2/CCR2 axis in fibrotic conditions affecting different organs.

Anti-Inflammatory Effect of Dietary Pentadecanoic Fatty Acid Supplementation on Inflammatory Bowel Disease in SAMP1/YitFc Mice

BACKGROUND/OBJECTIVES

Dietary fats have been linked to the increasing incidence of chronic diseases, including inflammatory bowel diseases (IBD), namely, Crohn's disease (CD).

METHODS

This study investigated the impact of pentadecanoic acid (C15:0), a type of an odd-numbered chain saturated fatty acid, for its potential anti-inflammatory properties in different mouse models of experimental IBD using the SAMP1/YitFc (SAMP) mouse line (14- or 24-week-old), including chronic ileitis and DSS-induced colitis. To quantitively assess the effect of C:15, we tested two dosages of C:15 in selected experiments in comparison to control mice. Intestinal inflammation and intestinal permeability were used as primary outcomes.

RESULTS

In ileitis, C:15 supplementation showed an anti-inflammatory effect in SAMP mice (e.g., a reduction in ileitis severity vs. control p < 0.0043), which was reproducible when mice were tested in the DSS model of colitis (e.g., reduced permeability vs. control p < 0.0006). Of relevance, even the short-term C:15 therapy prevented colitis in mice by maintaining body weight, decreasing inflammation, preserving gut integrity, and alleviating colitis signs.

CONCLUSIONS

Collectively, the findings from both ileitis and colitis in SAMP mice indicate that C:15 may have therapeutic effects in the treatment of IBD (colitis in the short term). This promising effect has major translational potential for the alleviation of IBD in humans.

Landscape of Interactions between Stromal and Myeloid Cells in Ileal Crohn's Disease; Indications of an Important Role for Fibroblast-Derived CCL-2

BACKGROUND AND AIMS

Monocyte recruitment in the lamina propria and inflammatory phenotype driven by the mucosal microenvironment is critical for the pathogenesis of inflammatory bowel disease. However, the stimuli responsible remain largely unknown. Recent works have focused on stromal cells, the main steady-state cellular component in tissue, as they produce pro-inflammatory chemokines that contribute to the treatment-resistant nature of IBD.

METHODS

We studied the regulation of these processes by examining the communication patterns between stromal and myeloid cells in ileal Crohn's disease (CD) using a complete single-cell whole tissue sequencing analysis pipeline and in vitro experimentation in mesenchymal cells.

RESULTS

We report expansion of S4 stromal cells and monocyte-like inflammatory macrophages in the inflamed mucosa and describe interactions that may establish sustained local inflammation. These include expression of CCL2 by S1 fibroblasts to recruit and retain monocytes and macrophages in the mucosa, where they receive signals for proliferation, survival, and differentiation to inflammatory macrophages from S4 stromal cells through molecules such as MIF, IFNγ, and FN1. The overexpression of CCL2 in ileal CD and its stromal origin was further demonstrated in vitro by cultured mesenchymal cells and intestinal organoids in the context of an inflammatory milieu.

CONCLUSIONS

Our findings outline an extensive cross-talk between stromal and myeloid cells, which may contribute to the onset and progression of inflammation in ileal Crohn's disease. Understanding the mechanisms underlying monocyte recruitment and polarization, as well as the role of stromal cells in sustaining inflammation, can provide new avenues for developing targeted therapies to treat IBD.

CCR2-dependent CX3CR1+ colonic macrophages promote Enterococcus faecalis dissemination

Enterococci are common commensal bacteria that colonize the gastrointestinal tracts of most mammals, including humans. Importantly, these bacteria are one of the leading causes of nosocomial infections. This study examined the role of colonic macrophages in facilitating Enterococcus faecalis infections in mice. We determined that depletion of colonic phagocytes resulted in the reduction of E. faecalis dissemination to the gut-draining mesenteric lymph nodes. Furthermore, we established that trafficking of monocyte-derived CX3CR1-expressing macrophages contributed to E. faecalis dissemination in a manner that was not reliant on CCR7, the conventional receptor involved in lymphatic migration. Finally, we showed that E. faecalis mutants with impaired intracellular survival exhibited reduced dissemination, suggesting that E. faecalis can exploit host immune cell migration to disseminate systemically and cause disease. Our findings indicate that modulation of macrophage trafficking in the context of antibiotic therapy could serve as a novel approach for preventing or treating opportunistic infections by disseminating enteric pathobionts like E. faecalis.

Microglial repopulation restricts ocular inflammation and choroidal neovascularization in mice

Introduction

Age-related macular degeneration (AMD) is a prevalent, chronic and progressive retinal degenerative disease characterized by an inflammatory response mediated by activated microglia accumulating in the retina. In this study, we demonstrate the therapeutically effects and the underlying mechanisms of microglial repopulation in the laser-induced choroidal neovascularization (CNV) model of exudative AMD.

Methods

The CSF1R inhibitor PLX3397 was used to establish a treatment paradigm for microglial repopulation in the retina. Neovascular leakage and neovascular area were examined by fundus fluorescein angiography (FFA) and immunostaining of whole-mount RPE-choroid-sclera complexes in CNV mice receiving PLX3397. Altered cellular senescence was measured by beta-galactosidase (SA-β-gal) activity and p16INK4a expression. The effect and mechanisms of repopulated microglia on leukocyte infiltration and the inflammatory response in CNV lesions were analyzed.

Results

We showed that ten days of the CSF1R inhibitor PLX3397 treatment followed by 11 days of drug withdrawal was sufficient to stimulate rapid repopulation of the retina with new microglia. Microglial repopulation attenuated pathological choroid neovascularization and dampened cellular senescence in CNV lesions. Repopulating microglia exhibited lower levels of activation markers, enhanced phagocytic function and produced fewer cytokines involved in the immune response, thereby ameliorating leukocyte infiltration and attenuating the inflammatory response in CNV lesions.

Discussion

The microglial repopulation described herein are therefore a promising strategy for restricting inflammation and choroidal neovascularization, which are important players in the pathophysiology of AMD.

Exploration of the core pathway of inflammatory bowel disease complicated with metabolic fatty liver and two-sample Mendelian randomization study of the causal relationships behind the disease

Background

Inflammatory bowel disease (IBD) is often associated with complex extraintestinal manifestations. The incidence of nonalcoholic fatty liver disease (NAFLD) in IBD populations is increasing yearly. However, the mechanism of interaction between NAFLD and IBD is not clear. Consequently, this study aimed to explore the common genetic characteristics of IBD and NAFLD and identify potential therapeutic targets.

Materials and methods

Gene chip datasets for IBD and NAFLD were obtained from the Gene Expression Omnibus (GEO) database. Weighted gene co-expression network analysis (WGCNA) was performed to identify modules in those datasets related to IBD and NAFLD. ClueGO was used for biological analysis of the shared genes between IBD and NAFLD. Based on the Human MicroRNA Disease Database (HMDD), microRNAs (miRNAs) common to NAFLD and IBD were obtained. Potential target genes for the miRNAs were predicted using the miRTarbase, miRDB, and TargetScan databases. Two-sample Mendelian randomization (MR) and two-way MR were used to explore the causal relationship between Interleukin-17 (IL-17) and the risk of IBD and NAFLD using data from GWAS retrieved from an open database.

Results

Through WGCNA, gene modules of interest were identified. GO enrichment analysis using ClueGO suggested that the abnormal secretion of chemokines may be a common pathophysiological feature of IBD and NAFLD, and that the IL-17-related pathway may be a common key pathway for the pathological changes that occur in IBD and NAFLD. The core differentially expressed genes (DEGs) in IBD and NAFLD were identified and included COL1A1, LUM, CCL22, CCL2, THBS2, COL1A2, MMP9, and CXCL8. Another cohort was used for validation. Finally, analysis of the miRNAs identified potential therapeutic targets. The MR results suggested that although there was no causal relationship between IBD and NAFLD, there were causal relationships between IL-17 and IBD and NAFLD.

Conclusion

We established a comorbid model to explain the potential mechanism of IBD with NAFLD and identified the chemokine-related pathway mediated by cytokine IL-17 as the core pathway in IBD with NAFLD, in which miRNA also plays a role and thus provides potential therapeutic targets.

CCR2: A characteristic chemokine receptor in normal and pathological intestine

C-C motif chemokine receptor 2 (CCR2), together with its ligands, especially C-C motif ligand 2 (CCL2), to which CCR2 has the highest affinity, form a noteworthy signaling pathway in recruiting macrophages for the immune responses among variegated disorders in vivo environment. Scientometric methods are used to analyze intestine-related CCR2 expression. We describe the current knowledge on biological function of CCR2 in physiological intestine in three dimensions, namely its effects on stromal cells, angiogenesis, and remodeling. However, anomalous expression of CCR2 has also been conveyed to correlate with detrimental outcomes in intestine, such as infective colitis, inflammatory bowel disease, carcinogenesis, and colon-related metastasis. In this article, we briefly summarize recent experimental works on CCR2 and its ligands, mostly CCL2, in intestinal-related physiological and pathological states to ravel out their working mechanisms in intestinal diseases.

Qing Hua Chang Yin alleviates chronic colitis of mice by protecting intestinal barrier function and improving colonic microflora

Background: Qing Hua Chang Yin (QHCY) is a famous formula of traditional Chinese medicine (TCM) and has been proven to have protective effect on ulcerative colitis. However, its protective effect and potential therapeutic mechanisms in chronic colitis remain unclear. The purpose of this study is to explore the effects and underlying mechanisms of QHCY on dextran sulfate sodium (DSS)-induced chronic colitis mice model. Methods: The chronic colitis model was established by administration of 2% DSS for three consecutive cycles of 7 days with two intervals of 14 days for recovery by drinking water. The experiment lasted 49 days. The DSS + QHCY group received QHCY administration by oral gavage at doses of 1.6 g/kg/d, DSS + Mesalazine group was administrated Mesalazine by oral gavage at doses of 0.2 g/kg/d. The control and DSS group were given equal volume of distilled water. The body weight, stool consistency and blood in stool were monitored every 2 days. The disease activity index (DAI) was calculated. The colon length was measured after the mice were sacrificed. The histomorphology of colonic tissues was checked by the HE and PAS staining. Immunohistochemistry was performed to detect the expressions of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6), tight junction proteins (ZO-1, occludin) and Mucin2 (MUC2). 16S rRNA sequencing analysis was conducted to study the diversity and abundance of gut microbiota changes. Results: QHCY treatment not only significantly attenuated DSS-induced the weight loss, DAI score increase, colon shortening and histological damage in mice, but also decreased the expression of pro-inflammatory cytokines in colonic tissues and increased the expression of ZO-1, occludin, and MUC2. Furthermore, QHCY enhanced the diversity of gut microbes and regulated the structure and composition of intestinal microflora in mice with chronic colitis. Conclusion: QHCY has a therapeutic effect on a murine model of chronic colitis. It can effectively reduce the clinical and pathological manifestations of colitis and prevent alterations in the gut microbiota.

Targeting the tumor microenvironment: Potential strategy for cancer therapeutics

Cellular and stromal components including tumor cells, immune cells, mesenchymal cells, cancer-linked fibroblasts, and extracellular matrix, constituent tumor microenvironment (TME). TME plays a crucial role in reprogramming tumor initiation, uncontrolled proliferation, invasion and metastasis as well as response to therapeutic modalities. In recent years targeting the TME has developed as a potential strategy for treatment of cancer because of its life-threatening functions in restricting tumor development and modulating responses to standard-of-care medicines. Cold atmospheric plasma, oncolytic viral therapy, bacterial therapy, nano-vaccine, and repurposed pharmaceuticals with combination therapy, antiangiogenic drugs, and immunotherapies are among the most effective therapies directed by TME that have either been clinically authorized or are currently being studied. This article discusses above-mentioned therapies in light of targeting TME. We also cover problems related to the TME-targeted therapies, as well as future insights and practical uses in this rapidly growing field.

Role of interleukin-6-mediated inflammation in the pathogenesis of inflammatory bowel disease: focus on the available therapeutic approaches and gut microbiome

Inflammatory bowel disease (IBD) is considered a chronic inflammatory and multifactorial disease of the gastrointestinal tract. Crohn's disease (CD) and ulcerative colitis (UC) are two types of chronic IBD. Although there is no accurate information about IBD pathophysiology, evidence suggests that various factors, including the gut microbiome, environment, genetics, lifestyle, and a dysregulated immune system, may increase susceptibility to IBD. Moreover, inflammatory mediators such as interleukin-6 (IL-6) are involved in the immunopathogenesis of IBDs. IL-6 contributes to T helper 17 (Th17) differentiation, mediating further destructive inflammatory responses in CD and UC. Moreover, Th1-mediated responses participate in IBD, and the antiapoptotic IL-6/IL-6 receptor (IL-6R)/signal transducer and activator of transcription 3 (STAT3) signals are responsible for preserving Th1 cells in the site of inflammation. It has been revealed that fecal bacteria isolated from UC-active and UC-remission patients stimulate the hyperproduction of several cytokines, such as IL-6, tumor necrosis factor-α (TNF-α), IL-10, and IL-12. Given the importance of the IL-6/IL-6R axis, various therapeutic options exist for controlling or treating IBD. Therefore, alternative therapeutic approaches such as modulating the gut microbiome could be beneficial due to the failure of the target therapies so far. This review article summarizes IBD immunopathogenesis focusing on the IL-6/IL-6R axis and discusses available therapeutic approaches based on the gut microbiome alteration and IL-6/IL-6R axis targeting and treatment failure.

Interleukin-26 Expression in Inflammatory Bowel Disease and Its Immunoregulatory Effects on Macrophages

Background and Aim

Interleukin-26 (IL-26) has been implicated in several chronic inflammatory diseases. However, its role in inflammatory bowel disease (IBD) remains to be elucidated. We aimed to investigate IL-26 expression in IBD and its immunoregulatory effects on macrophages.

Methods

We assessed IL-26 expression in the intestinal mucosa and blood samples of IBD patients and healthy controls (HC). The associations between the clinical characteristics of IBD and IL-26 expression levels in serum and peripheral blood mononuclear cells (PBMCs) were investigated. In addition, the transcriptional changes in THP-1 macrophages exposed to IL-26 were determined by RNA sequencing and validated with qRT-PCR, ELISA and western blots.

Results

Compared with HC, in IBD patients, IL-26 expression levels were elevated in the inflamed intestinal mucosa, and reduced in serum and PBMCs. IL-26 mRNA levels in PBMCs, but not serum IL-26 levels, were inversely correlated with disease activity in IBD. Furthermore, IL-26 mRNA levels in PBMCs were significantly lower in patients with complicated Crohn's disease. A total of 1,303 differentially expressed protein-coding genes were identified between untreated and IL-26-treated macrophages. The up-regulated genes showed enrichment in some inflammatory and immune-related processes and pathways. Additionally, GSEA showed that neutrophil, monocyte, and lymphocyte chemotaxis was significantly enriched in IL-26-treated macrophages. Further validation revealed that IL-26 promotes the secretion of multiple inflammatory cytokines and chemokines and upregulates the expression of adhesion molecules, MMP-8, and MMP-9 while inhibiting MMP-1 in macrophages.

Conclusion

Compared with HC, in IBD patients, IL-26 levels were elevated in the inflamed intestinal mucosa, and reduced in the peripheral blood. The transcriptional changes in macrophages exposed to IL-26 suggest that IL-26 may amplify the aberrant immune response in IBD by activating macrophages.

Chemokines and chemokine receptors in inflammatory bowel disease: Recent findings and future perspectives

Despite the benefits of current therapeutic options for treating inflammatory bowel disease (IBD), there are still patients who are refractory to these therapies. Moreover, the relapses caused by incomplete intestinal mucosa healing are frequent. Therefore, there is a need for novel pharmacological targets that can improve the existing IBD therapeutic armamentarium. Chemokine and chemokine receptors have emerged as appealing options to this end. As well as controlling leukocyte trafficking to inflamed tissues, these proteins regulate many other processes related to the development of intestinal inflammation. In this review, we summarise the most recent preclinical studies, along with the putative application of chemokine-based therapies in patients with IBD.