Regulation of wound healing and organ fibrosis by toll-like receptors

Comparative analysis of human and mouse transcriptomes during skin wound healing

Skin wound healing is a complex process which involves multiple molecular events and the underlying mechanism is not fully understood. We presented a comparative transcriptomic analysis of skin wound healing in humans and mice to identify shared molecular mechanisms across species. We analyzed transcriptomes from three distinct stages of the healing process and constructed protein-protein interaction networks to elucidate commonalities in the healing process. A substantial number of differentially expressed genes (DEGs) were identified in human transcriptomes, particularly upregulated genes before and after wound injury, and enriched in processes related to extracellular matrix organization and leukocyte migration. Similarly, the mouse transcriptome revealed thousands of DEGs, with shared biological processes and enriched KEGG pathways, highlighting a conserved molecular signature in skin wound healing. A total of 21 common DEGs were found across human comparisons, and 591 in mouse comparisons, with four genes (KRT2, MARCKSL1, MMP1, and TNC) consistently differentially expressed in both species, suggesting critical roles in mammalian skin wound healing. The expression trends of these genes were consistent, indicating their potential as therapeutic targets. The molecular network analysis identified five subnetworks associated with collagen synthesis, immunity, cell-cell adhesion, and extracellular matrix, with hub genes such as COL4A1, TLR7, TJP3, MMP13, and HIF1A exhibited significant expression changes before and after wound injury in humans and mice. In conclusion, our study provided a detailed molecular network for understanding the healing process in humans and mice, revealing conserved mechanisms that could help the development of targeted therapies across species.

TLR-2 and TLR-4 mRNA expression in different grades of histopathological lesions of equine endometrium from follicular phase

Increased synthesis and deposition of collagen (COL) in the extracellular matrix (ECM) of equine endometrium contributes to endometrosis. Toll-like receptors (TLRs) are transmembrane receptors involved in the innate immune response, recognized for their role in antigen recognition and previously associated with equine endometritis. The TLRs not only recognize pathogen-associated molecular patterns but also regulate inflammations, fibrosis and cancer. The aim of this study was to explore the relationship between TLR expression at different stages of Kenney and Doig's (K-D) grading and COL1 expression during the follicular phase of the oestrous cycle. Forty samples of endometrial tissues were collected post-mortem from mares on the follicular phase of the oestrous cycle (10 samples of each K-D category). Relative mRNA transcription of TLR-2, TLR-4 and COL1A2 genes was assessed using qPCR, and COL1 protein expression by Western blot analysis. The COL1A2 transcription increased in category IIB when compared to categories I, IIA and III endometria (p < .01). The relative protein abundance of COL1 showed no significant differences between endometrial categories (p > .05). As for the TLRs mRNA transcription, TLR-2/-4 transcripts increased in IIA when compared to the other K-D endometria categories (p < .05). Our findings suggest that TLRs may be involved in the initiation of the endometrial inflammatory response. Additional studies are needed to explore TLRs' potential role as diagnostic markers for monitoring inflammation progression and fibrosis development, as well as their involvement in the mechanisms underlying fibrotic pathways.

Metabolism and bioenergetics in the pathophysiology of organ fibrosis

Fibrosis is the tissue scarring characterized by excess deposition of extracellular matrix (ECM) proteins, mainly collagens. A fibrotic response can take place in any tissue of the body and is the result of an imbalanced reaction to inflammation and wound healing. Metabolism has emerged as a major driver of fibrotic diseases. While glycolytic shifts appear to be a key metabolic switch in activated stromal ECM-producing cells, several other cell types such as immune cells, whose functions are intricately connected to their metabolic characteristics, form a complex network of pro-fibrotic cellular crosstalk. This review purports to clarify shared and particular cellular responses and mechanisms across organs and etiologies. We discuss the impact of the cell-type specific metabolic reprogramming in fibrotic diseases in both experimental and human pathology settings, providing a rationale for new therapeutic interventions based on metabolism-targeted antifibrotic agents.

Fibrosis and Hepatocarcinogenesis: Role of Gene-Environment Interactions in Liver Disease Progression

The liver is a complex organ that performs vital functions in the body. Despite its extraordinary regenerative capacity compared to other organs, exposure to chemical, infectious, metabolic and immunologic insults and toxins renders the liver vulnerable to inflammation, degeneration and fibrosis. Abnormal wound healing response mediated by aberrant signaling pathways causes chronic activation of hepatic stellate cells (HSCs) and excessive accumulation of extracellular matrix (ECM), leading to hepatic fibrosis and cirrhosis. Fibrosis plays a key role in liver carcinogenesis. Once thought to be irreversible, recent clinical studies show that hepatic fibrosis can be reversed, even in the advanced stage. Experimental evidence shows that removal of the insult or injury can inactivate HSCs and reduce the inflammatory response, eventually leading to activation of fibrolysis and degradation of ECM. Thus, it is critical to understand the role of gene-environment interactions in the context of liver fibrosis progression and regression in order to identify specific therapeutic targets for optimized treatment to induce fibrosis regression, prevent HCC development and, ultimately, improve the clinical outcome.

Exploring the potential of drug repurposing for liver diseases: A comprehensive study

Drug repurposing involves the investigation of existing drugs for new indications. It offers a great opportunity to quickly identify a new drug candidate at a lower cost than novel discovery and development. Despite the importance and potential role of drug repurposing, there is no specific definition that healthcare providers and the World Health Organization credit. Unfortunately, many similar and interchangeable concepts are being used in the literature, making it difficult to collect and analyze uniform data on repurposed drugs. This research was conducted based on understanding general criteria for drug repurposing, concentrating on liver diseases. Many drugs have been investigated for their effect on liver diseases even though they were originally approved (or on their way to being approved) for other diseases. Some of the hypotheses for drug repurposing were first captured from the literature and then processed further to test the hypothesis. Recently, with the revolution in bioinformatics techniques, scientists have started to use drug libraries and computer systems that can analyze hundreds of drugs to give a short list of candidates to be analyzed pharmacologically. However, this study revealed that drug repurposing is a potential aid that may help deal with liver diseases. It provides available or under-investigated drugs that could help treat hepatitis, liver cirrhosis, Wilson disease, liver cancer, and fatty liver. However, many further studies are needed to ensure the efficacy of these drugs on a large scale.

Proanthocyanidins-based tandem dynamic covalent cross-linking hydrogel for diabetic wound healing

Wound healing in diabetic patients presents significant challenges in clinical wound care due to high oxidative stress, excessive inflammation, and a microenvironment prone to infection. In this study, we successfully developed a multifunctional tandem dynamic covalently cross-linked hydrogel dressing aimed at diabetic wound healing. This hydrogel was constructed using cyanoacetic acid functionalized dextran (Dex-CA), 2-formylbenzoylboric acid (2-FPBA) and natural oligomeric proanthocyanidins (OPC), catalyzed by histidine. The resulting Dex-CA/OPC/2-FPBA (DPOPC) hydrogel can be dissolved triggered by cysteine, thereby achieving "controllable and non-irritating" dressing change. Furthermore, the incorporation of OPC as a hydrogel building block endowed the hydrogel with antioxidant and anti-inflammatory properties. The cross-linked network of the DPOPC hydrogel circumvents the burst release of OPC, enhancing its biosafety. In vivo studies demonstrated that the DPOPC hydrogel significantly accelerated the wound healing process in diabetic mice compared to a commercial hydrogel, achieving an impressive wound closure rate of 98 % by day 14. The DPOPC hydrogel effectively balanced the disrupted inflammatory state during the healing process. This dynamic hydrogel based on natural polyphenols is expected to be an ideal candidate for dressings intended for chronic wounds.

TLR8 aggravates skin inflammation and fibrosis by activating skin fibroblasts in systemic sclerosis

OBJECTIVES

Innate immunity significantly contributes to SSc pathogenesis. TLR8 is an important innate immune mediator that is implicated in autoimmunity and fibrosis. However, the expression, mechanism of action, and pathogenic role of TLR8 in SSc remain unclear. The aim of this study was to explore the roles and underlying mechanisms of TLR8 in SSc.

METHODS

The expression of TLR8 was analysed, based on a public dataset, and then verified in skin tissues and skin fibroblasts of SSc patients. The role of TLR8 in inflammation and fibrosis was investigated using a TLR8-overexpression vector, activator (VTX-2337), inhibitor (cu-cpt-8m), and TLR8 siRNA in skin fibroblasts. The pathogenic role of TLR8 in skin inflammation and fibrosis was further validated in a bleomycin (BLM)-induced mouse skin inflammation and fibrosis model.

RESULTS

TLR8 levels were significantly elevated in SSc skin tissues and myofibroblasts, along with significant activation of the TLR8 pathway. In vitro studies showed that overexpression or activation of TLR8 by a recombinant plasmid or VTX-2337 upregulated IL-6, IL-1β, COL I, COL III and α-SMA in skin fibroblasts. Consistently, both TLR8-siRNA and cu-cpt-8m reversed the phenotypes observed in TLR8-activating fibroblasts. Mechanistically, TLR8 induces skin fibrosis and inflammation in a manner dependent on the MAPK, NF-κB and SMAD2/3 pathways. Subcutaneous injection of cu-cpt-8m significantly alleviated BLM-induced skin inflammation and fibrosis in vivo.

CONCLUSION

TLR8 might be a promising therapeutic target for improving the treatment strategy for skin inflammation and fibrosis in SSc.

Metabolic reprogramming heterogeneity in chronic kidney disease

Fibrosis driven by excessive accumulation of extracellular matrix (ECM) is the hallmark of chronic kidney disease (CKD). Myofibroblasts, which are the cells responsible for ECM production, are activated by cross talk with injured proximal tubule and immune cells. Emerging evidence suggests that alterations in metabolism are not only a feature of but also play an influential role in the pathogenesis of renal fibrosis. The application of omics technologies to cell-tracing animal models and follow-up functional data suggest that cell-type-specific metabolic shifts have particular roles in the fibrogenic response. In this review, we cover the main metabolic reprogramming outcomes in renal fibrosis and provide a future perspective on the field of renal fibrometabolism.

Toll-like receptor 5 tunes hepatic and pancreatic stellate cells activation

OBJECTIVE

Stellate cells are responsible for liver and pancreas fibrosis and strictly correlate with tumourigenesis. Although their activation is reversible, an exacerbated signalling triggers chronic fibrosis. Toll-like receptors (TLRs) modulate stellate cells transition. TLR5 transduces the signal deriving by the binding to bacterial flagellin from invading mobile bacteria.

DESIGN

Human hepatic and pancreatic stellate cells were activated by the administration of transforming growth factor-beta (TGF-β). TLR5 was transiently knocked down by short-interference RNA transfection. Reverse Transcription-quantitativePCR and western blot were performed to analyse the transcript and protein level of TLR5 and the transition players. Fluorescence microscopy was performed to identify these targets in spheroids and in the sections of murine fibrotic liver.

RESULTS

TGF-β-activated human hepatic and pancreatic stellate cells showed an increase of TLR5 expression. TLR5 knockdown blocked the activation of those stellate cells. Furthermore, TLR5 busted during murine liver fibrosis and co-localised with the inducible Collagen I. Flagellin suppressed TLR5, COL1A1 and ACTA2 expression after the administration of TGF-β. Instead, the antagonist of TLR5 did not block the effect of TGF-β. Wortmannin, a specific AKT inhibitor, induced TLR5 but not COL1A1 and ACTA2 transcript and protein level.

CONCLUSION

TGF-β-mediated activation of hepatic and pancreatic stellate cells requires the over-expression of TLR5. Instead, its autonomous signalling inhibits the activation of the stellate cells, thus prompting a signalling through different regulatory pathways.

Endothelial Dysfunction in Patients Undergoing Cardiac Surgery: A Narrative Review and Clinical Implications

Cardiac surgery is one of the highest-risk procedures, usually involving cardiopulmonary bypass and commonly inducing endothelial injury that contributes to the development of perioperative and postoperative organ dysfunction. Substantial scientific efforts are being made to unravel the complex interaction of biomolecules involved in endothelial dysfunction to find new therapeutic targets and biomarkers and to develop therapeutic strategies to protect and restore the endothelium. This review highlights the current state-of-the-art knowledge on the structure and function of the endothelial glycocalyx and mechanisms of endothelial glycocalyx shedding in cardiac surgery. Particular emphasis is placed on potential strategies to protect and restore the endothelial glycocalyx in cardiac surgery. In addition, we have summarized and elaborated the latest evidence on conventional and potential biomarkers of endothelial dysfunction to provide a comprehensive synthesis of crucial mechanisms of endothelial dysfunction in patients undergoing cardiac surgery, and to highlight their clinical implications.

Dietary Bacillus licheniformis shapes the foregut microbiota, improving nutrient digestibility and intestinal health in broiler chickens

Bacillus licheniformis is considered a potential alternative to antibiotic growth promoters of animal growth and health. However, the effects of Bacillus licheniformis on the foregut and hindgut microbiota, and their relationships with nutrient digestion and health, in broiler chickens remain unclear. In this study, we aimed to identify the effects of Bacillus licheniformis BCG on intestinal digestion and absorption, tight junctions, inflammation, and the fore- and hind-gut microbiota. We randomly assigned 240 1-day-old male AA broilers into three treatment groups: CT (basal diet), BCG1 (basal diet + 1.0 × 10⁸ CFU/kg B. licheniformis BCG), and BCG2 (basal diet + 1.0 × 10⁹ CFU/kg B. licheniformis BCG). On day 42, the jejunal and ileal chyme and mucosa were subjected to analysis of digestive enzyme activity, nutrient transporters, tight junctions, and signaling molecules associated with inflammation. The ileal and cecal chyme were subjected to microbiota analysis. Compared with the CT group, the B. licheniformis BCG group showed significantly greater jejunal and ileal α-amylase, maltase, and sucrase activity; moreover, the α-amylase activity in the BCG2 group was higher than that in the BCG1 group (P < 0.05). The transcript abundance of FABP-1 and FATP-1 in the BCG2 group was significantly greater than that in the CT and BCG1 groups, and the GLUT-2 and LAT-1 relative mRNA levels were greater in the BCG2 group than the CT group (P < 0.05). Dietary B. licheniformis BCG resulted in significantly higher ileal occludin, and lower IL-8 and TLR-4 mRNA levels than observed in the CT group (P < 0.05). B. licheniformis BCG supplementation significantly decreased bacterial community richness and diversity in the ileum (P < 0.05). Dietary B. licheniformis BCG shaped the ileac microbiota by increasing the prevalence of f_Sphingomonadaceae, Sphingomonas, and Limosilactobacillus, and contributed to nutrient digestion and absorption; moreover, it enhanced the intestinal barrier by increasing the prevalence of f_Lactobacillaceae, Lactobacillus, and Limosilactobacillus. Dietary B. licheniformis BCG decreased microbial community diversity by diminishing Desulfovibrio, Alistipes, Campylobacter, Vibrio, Streptococcus, and Escherichia coli-Shigella levels, and down-regulating inflammatory associated molecule expression. Therefore, dietary B. licheniformis BCG contributed to digestion and absorption of nutrients, enhanced the intestinal physical barrier, and decreased intestinal inflammation in broilers by decreasing microbial diversity and optimizing the microbiota structure.

Anti-liver fibrosis activity of curcumin/chitosan-coated green silver nanoparticles

Liver fibrosis results from the hepatic accumulation of the extracellular matrix accompanied by a failure of the mechanisms responsible for matrix dissolution. Pathogenesis of liver fibrosis is associated with many proteins from different cell types. In the present study, in silico molecular docking analysis revealed that curcumin may inhibit the fibrosis-mediating proteins PDGF, PDGFRB, TIMP-1, and TLR-9 by direct binding. Nano-formulation can overcome curcumin problems, increasing the efficacy of curcumin as a drug by maximizing its solubility and bioavailability, enhancing its membrane permeability, and improving its pharmacokinetics, pharmacodynamics and biodistribution. Therefore, green silver nanoparticles (AgNPs) were synthesized in the presence of sunlight by means of the metabolite of Streptomyces malachiticus, and coated with curcumin-chitosan mixture to serve as a drug delivery tool for curcumin to target CCl4-induced liver fibrosis mouse model. Fibrosis induction significantly increased hepatic gene expression of COL1A1, α-SMA, PDGFRB, and TIMP1, elevated hepatic enzymes, increased histopathological findings, and increased collagen deposition as determined by Mason's trichrome staining. Treatment with naked AgNPs tended to increase these inflammatory effects, while their coating with chitosan, similar to treatment with curcumin only, did not prevent the fibrogenic effect of CCl4. The induction of liver fibrosis was reversed by concurrent treatment with curcumin/chitosan-coated AgNPs. In this nano form, curcumin was found to be efficient as anti-liver fibrosis drug, maintaining the hepatic architecture and function during fibrosis development. This efficacy can be attributed to its inhibitory role through a direct binding to fibrosis-mediating proteins such as PDGFRB, TIMP-1, TLR-9 and TGF-β.

Recent insights into the role of defensins in diabetic wound healing

Diabetic wound, one of the most common serious complications of diabetic patients, is an important factor in disability and death. Much of the research on the pathophysiology of diabetic wound healing has long focused on mechanisms mediated by hyperglycemia, chronic inflammation, microcirculatory and macrocirculatory dysfunction. However, recent evidence suggests that defensins may play a crucial role in the development and perpetuation of diabetic wound healing. The available findings suggest that defensins exert a beneficial influence on diabetic wound healing through antimicrobial, immunomodulatory, angiogenic, tissue regenerator effects, and insulin resistance improvement. Therefore, summarizing the existing research progress on defensins in the diabetic wound may present a promising strategy for diabetic patients.

Single-cell mapping of regenerative and fibrotic healing responses after musculoskeletal injury

After injury, a cascade of events repairs the damaged tissue, including expansion and differentiation of the progenitor pool and redeposition of matrix. To guide future wound regeneration strategies, we compared single-cell sequencing of regenerative (third phalangeal element [P3]) and fibrotic (second phalangeal element [P2]) digit tip amputation (DTA) models as well as traumatic heterotopic ossification (HO; aberrant). Analyses point to a common initial response to injury, including expansion of progenitors, redeposition of matrix, and activation of transforming growth factor β (TGF-β) and WNT pathways. Surprisingly, fibrotic P2 DTA showed greater transcriptional similarity to HO than to regenerative P3 DTA, suggesting that gene expression more strongly correlates with healing outcome than with injury type or cell origin. Differential analysis and immunostaining revealed altered activation of inflammatory pathways, such as the complement pathway, in the progenitor cells. These data suggests that common pathways are activated in response to damage but are fine tuned within each injury. Modulating these pathways may shift the balance toward regenerative outcomes.

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Regenerative and fibrotic injuries share common early response mechanisms

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Transcriptomes correlate with healing outcome more than injury type or cell source

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Matrix composition after injury-induced tissue repair is highly injury type dependent

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Inflammatory cascades are activated in immune and mesenchymal cells

Relaxin Inhibits the Cardiac Myofibroblast NLRP3 Inflammasome as Part of Its Anti-Fibrotic Actions via the Angiotensin Type 2 and ATP (P2X7) Receptors

Chronic NLRP3 inflammasome activation can promote fibrosis through its production of interleukin (IL)-1β and IL-18. Conversely, recombinant human relaxin (RLX) can inhibit the pro-fibrotic interactions between IL-1β, IL-18 and transforming growth factor (TGF)-β1. Here, the broader extent by which RLX targeted the myofibroblast NLRP3 inflammasome to mediate its anti-fibrotic effects was elucidated. Primary human cardiac fibroblasts (HCFs), stimulated with TGF-β1 (to promote myofibroblast (HCMF) differentiation), LPS (to prime the NLRP3 inflammasome) and ATP (to activate the NLRP3 inflammasome) (T+L+A) or benzoylbenzoyl-ATP (to activate the ATP receptor; P2X7R) (T+L+Bz), co-expressed relaxin family peptide receptor-1 (RXFP1), the angiotensin II type 2 receptor (AT2R) and P2X7R, and underwent increased protein expression of toll-like receptor (TLR)-4, NLRP3, caspase-1, IL-1β and IL-18. Whilst RLX co-administration to HCMFs significantly prevented the T+L+A- or T+L+Bz-stimulated increase in these end points, the inhibitory effects of RLX were annulled by the pharmacological antagonism of either RXFP1, AT2R, P2X7R, TLR-4, reactive oxygen species (ROS) or caspase-1. The RLX-induced amelioration of left ventricular inflammation, cardiomyocyte hypertrophy and fibrosis in isoproterenol (ISO)-injured mice, was also attenuated by P2X7R antagonism. Thus, the ability of RLX to ameliorate the myofibroblast NLRP3 inflammasome as part of its anti-fibrotic effects, appeared to involve RXFP1, AT2R, P2X7R and the inhibition of TLR-4, ROS and caspase-1.

Foamy macrophages potentially inhibit tuberculous wound healing by inhibiting the TLRs/NF-κB signalling pathway

To characterise the distribution, classification, and quantity of foamy macrophages (FMs) in tuberculous wound tissue and the relationship between FM and delayed healing of tuberculous wounds. Morphological studies were performed to explore the distribution of FM and Mycobacterium tuberculosis (Mtb) in tuberculous wounds, with acute and chronic wounds included for comparison. Phorbol-12-myristate-13-acetate stimulation-differentiated THP-1 cells were treated with Mtb to induce their differentiation into FM with oxidised low-density lipoprotein treatment serving as a control. Relative cytokine levels were determined by quantitative PCR and Western blotting. Varied co-culture combinations of Mtb, THP-1, FM, and fibroblasts were performed, and proliferation, migration, ability to contract collagen gel, and protein levels of the chemokines in the supernatants of the fibroblasts were assessed. The differentially expressed genes in human skin fibroblasts (HSFs) after co-culture with or without FM were identified using microarray. Many FM were found in the tissues of tuberculous wounds. The FM that did not engulf Mtb (NM-FM) were mainly distributed in tissues surrounding tuberculous wounds, whereas the FM that engulfed Mtb (M-FM) were dominantly located within granulomatous tissues. Co-culture experiments showed that, with the Mtb co-culture, the portions of NM-FM in the total FM grew over time. The migration, proliferation, chemokine secretion, and the ability of fibroblasts to contract collagen gel were inhibited when co-cultured with Mtb, FM, or a combination of the two. Further investigation showed that the TLRs/NF-κB signalling pathway is involved in fibroblast function under the stimulation of FM. TLRs and NF-κB agonists could reverse the phenotypic changes in HSFs after co-culture with FM. The tuberculous wound microenvironment composed of Mtb and FM may affect wound healing by inhibiting the functions of fibroblasts. FM potentially inhibit fibroblasts' function by inhibiting the TLRs/NF-κB signalling pathway in tuberculous wounds.

Inflammatory Microenvironment of Skin Wounds

Wound healing is a dynamic and highly regulated process that can be separated into three overlapping and interdependent phases: inflammation, proliferation, and remodelling. This review focuses on the inflammation stage, as it is the key stage of wound healing and plays a vital role in the local immune response and determines the progression of wound healing. Inflammatory cells, the main effector cells of the inflammatory response, have been widely studied, but little attention has been paid to the immunomodulatory effects of wound healing in non-inflammatory cells and the extracellular matrix. In this review, we attempt to deepen our understanding of the wound-healing microenvironment in the inflammatory stage by focusing on the interactions between cells and the extracellular matrix, as well as their role in regulating the immune response during the inflammatory stage. We hope our findings will provide new ideas for promoting tissue regeneration through immune regulation.

Effects of Multispecies Probiotic on Intestinal Microbiota and Mucosal Barrier Function of Neonatal Calves Infected With E. coli K99

Altered gut microbiota are implicated in inflammatory neonatal calf diarrhea caused by E. coli K99. Beneficial probiotics are used to modulate gut microbiota. However, factors that mediate host-microbe interactions remain unclear. We evaluated the effects of a combination of multispecies probiotics (MSP) on growth, intestinal epithelial development, intestinal immune function and microbiota of neonatal calves infected with E. coli K99. Twelve newborn calves were randomly assigned as follows: C (control, without MSP); D (E. coli O78:K99 + gentamycin); and P (E. coli O78:K99 + supplemental MSP). All groups were studied for 21 d. MSP supplementation significantly (i) changed fungal Chao1 and Shannon indices of the intestine compared with group D; (ii) reduced the relative abundance of Bacteroides and Actinobacteria, while increasing Bifidobacteria, Ascomycetes, and Saccharomyces, compared with groups C and D; (iii) improved duodenal and jejunal mucosal SIgA and total Short Chain Fatty Acids (SCFA) concentrations compared with group D; (iv) increased relative ZO-1 and occludin mRNA expression in jejunal mucosa compared with group D; and (v) enhanced intestinal energy metabolism and defense mechanisms of calves by reducing HSP90 expression in E. coli K99, thereby alleviating the inflammatory response and promoting recovery of mucosal function. Our research may provide direct theoretical support for future applications of MSP in ruminant production.

Molecular pathways and role of epigenetics in the idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease with unknown etiological factors that can progress to other dangerous diseases like lung cancer. Environmental and genetic predisposition are the two major etiological or risk factors involved in the pathology of the IPF. Among the environmental risk factors, smoking is one of the major causes for the development of IPF. Epigenetic pathways like nucleosomes remodeling, DNA methylation, histone modifications and miRNA mediated genes play a crucial role in development of IPF. Mutations in the genes make the epigenetic factors as important drug targets in IPF. Transcriptional changes due to environmental factors are also involved in the progression of IPF. The mutations in human telomerase reverse transcriptase (hTERT) have shown decreased life expectancy in IPF patients. The TERT-gene is highly expressed in chronic smokers and makes the role of epigenetics evident. Drug like nintedanib acts through vascular endothelial growth factor receptors (VEGFR), while drug pirfenidone acts through transforming growth factor (TGF), which is useful in IPF. Gefitinib, a tyrosine kinase inhibitor of EGFR, is useful as an anti-fibrosis agent in preclinical models. Newer drugs such as Celgene-CC90001 and FibroGen-FG-3019 are currently under investigations acts through the modulating epigenetic mechanisms. Thus, the study on epigenetics opens a wide window for the discovery of newer drugs. This study provides an elementary analysis of multiple regulators of epigenetics and their roles associated with the pathology of IPF. Further, this review also includes epigenetic drugs under development in preclinical and clinical stages.

Toll-Like Receptors (TLRs) in Health and Disease: An Overview

Toll-like receptors were discovered as proteins playing a crucial role in the dorsoventral patterning during embryonic development in the Drosophila melanogaster (D. melanogaster) almost 40 years ago. Subsequently, further research also showed a role of the Toll protein or Toll receptor in the recognition of Gram-positive bacterial and fungal pathogens infecting D. melanogaster. In 1997, the human homolog was reported and the receptor was named the Toll-like receptor 4 (TLR4) that recognizes lipopolysaccharide (LPS) of the Gram-negative bacteria as a pathogen-associated molecular pattern (PAMP). Identification of TLR4 in humans filled the long existing gap in the field of infection and immunity, addressing the mystery surrounding the recognition of foreign pathogens/microbes by the immune system. It is now known that mammals (mice and humans) express 13 different TLRs that are expressed on the outer cell membrane or intracellularly, and which recognize different PAMPs or microbe-associated molecular patterns (MAMPs) and death/damage-associated molecular patterns (DAMPs) to initiate the protective immune response. However, their dysregulation generates profound and prolonged pro-inflammatory immune responses responsible for different inflammatory and immune-mediated diseases. This chapter provides an overview of TLRs in the control of the immune response, their association with different diseases, including TLR single nucleotide polymorphisms (SNPs), interactions with microRNAs (miRs), use in drug development and vaccine design, and expansion in neurosciences to include pain, addiction, metabolism, reproduction, and wound healing.

Toll-like receptors and hepatitis C virus infection

BACKGROUND

Hepatitis C virus (HCV) infection is a worldwide issue. However, the current treatment for hepatitis C has many shortcomings. Toll-like receptors (TLRs) are pattern recognition receptors involved in HCV infection, and an increasing number of studies are focusing on the role of TLRs in the progression of hepatitis C.

DATA SOURCES

We performed a PubMed search up to January 2021 with the following keywords: hepatitis C, toll-like receptors, interferons, inflammation, and immune evasion. We also used terms such as single-nucleotide polymorphisms (SNPs), susceptibility, fibrosis, cirrhosis, direct-acting antiviral agents, agonists, and antagonists to supplement the query results. We reviewed relevant publications analyzing the correlation between hepatitis C and TLRs and the role of TLRs in HCV infection.

RESULTS

TLRs 1-4 and 6-9 are involved in the process of HCV infection. When the host is exposed to the HCV, TLRs, as important participants in HCV immune evasion, trigger innate immunity to remove the virus and also promote inflammation and liver fibrosis. TLR gene SNPs affect hepatitis C susceptibility, treatment, and prognosis. The contribution of each TLR to HCV is different. Drugs targeting various TLRs are developed and validated, and TLRs can synergize with classic hepatitis C drugs, including interferon and direct-acting antiviral agents, constituting a new direction for the treatment of hepatitis C.

CONCLUSIONS

TLRs are important receptors in HCV infection. Different TLRs induce different mechanisms of virus clearance and inflammatory response. Although TLR-related antiviral therapy strategies exist, more studies are needed to explore the clinical application of TLR-related drugs.

MyD88 in Macrophages Enhances Liver Fibrosis by Activation of NLRP3 Inflammasome in HSCs

Chronic liver disease mediated by the activation of hepatic stellate cells (HSCs) leads to liver fibrosis. The signal adaptor MyD88 of Toll-like receptor (TLR) signaling is involved during the progression of liver fibrosis. However, the specific role of MyD88 in myeloid cells in liver fibrosis has not been thoroughly investigated. In this study, we used a carbon tetrachloride (CCl₄)-induced mouse fibrosis model in which MyD88 was selectively depleted in myeloid cells. MyD88 deficiency in myeloid cells attenuated liver fibrosis in mice and decreased inflammatory cell infiltration. Furthermore, deficiency of MyD88 in macrophages inhibits the secretion of CXC motif chemokine 2 (CXCL2), which restrains the activation of HSCs characterized by NLR Family Pyrin Domain Containing 3 (NLRP3) inflammasome activation. Moreover, targeting CXCL2 by CXCR2 inhibitors attenuated the activation of HSCs and reduced liver fibrosis. Thus, MyD88 may represent a potential candidate target for the prevention and treatment of liver fibrosis.

Neutrophil extracellular traps impair regeneration

Fibrosis is a major health burden across diseases and organs. To remedy this, we study wound‐induced hair follicle neogenesis (WIHN) as a model of non‐fibrotic healing that recapitulates embryogenesis for de novo hair follicle morphogenesis after wounding. We previously demonstrated that TLR3 promotes WIHN through binding wound‐associated dsRNA, the source of which is still unclear. Here, we find that multiple distinct contexts of high WIHN all show a strong neutrophil signature. Given the correlation between neutrophil infiltration and endogenous dsRNA release, we hypothesized that neutrophil extracellular traps (NETs) likely release nuclear spliceosomal U1 dsRNA and modulate WIHN. However, rather than enhance regeneration, we find mature neutrophils inhibit WIHN such that mice with mature neutrophil depletion exhibit higher WIHN. Similarly, Pad4 null mice, which are defective in NET production, show augmented WIHN. Finally, using single‐cell RNA sequencing, we identify a dramatic increase in mature and activated neutrophils in the wound beds of low regenerating Tlr3−/− mice. Taken together, these results demonstrate that although mature neutrophils are stimulated by a common pro‐regenerative cue, their presence and NETs hinder regeneration.

Extracellular Vesicles as Therapeutic Tools for the Treatment of Chronic Wounds

Chronic wounds develop when the orderly process of cutaneous wound healing is delayed or disrupted. Development of a chronic wound is associated with significant morbidity and financial burden to the individual and health-care system. Therefore, new therapeutic modalities are needed to address this serious condition. Mesenchymal stem cells (MSCs) promote skin repair, but their clinical use has been limited due to technical challenges. Extracellular vesicles (EVs) are particles released by cells that carry bioactive molecules (lipids, proteins, and nucleic acids) and regulate intercellular communication. EVs (exosomes, microvesicles, and apoptotic bodies) mediate key therapeutic effects of MSCs. In this review we examine the experimental data establishing a role for EVs in wound healing. Then, we explore techniques for designing EVs to function as a targeted drug delivery system and how EVs can be incorporated into biomaterials to produce a personalized wound dressing. Finally, we discuss the status of clinically deploying EVs as a therapeutic agent in wound care.

Evolving Perspectives on Innate Immune Mechanisms of IPF

While epithelial-fibroblast interactions are viewed as the primary drivers of Idiopathic Pulmonary Fibrosis (IPF), evidence gleaned from animal modeling and human studies implicates innate immunity as well. To provide perspective on this topic, this review synthesizes the available data regarding the complex role of innate immunity in IPF. The role of substances present in the fibrotic microenvironment including pathogen associated molecular patterns (PAMPs) derived from invading or commensal microbes, and danger associated molecular patterns (DAMPs) derived from injured cells and tissues will be discussed along with the proposed contribution of innate immune populations such as macrophages, neutrophils, fibrocytes, myeloid suppressor cells, and innate lymphoid cells. Each component will be considered in the context of its relationship to environmental and genetic factors, disease outcomes, and potential therapies. We conclude with discussion of unanswered questions and opportunities for future study in this area.

Metabolomics: Impact of Comorbidities and Inflammation on Sickness Behaviors for Individuals with Chronic Wounds

Significance: Approximately 6.5 million people in the United States suffer from chronic wounds. The chronic wound population is typically older and is characterized by a number of comorbidities associated with inflammation. In addition to experiencing wound-related pain, individuals with chronic wounds commonly experience multiple concurrent psychoneurological symptoms such as fatigue and depression, which delay wound healing. However, these distressing symptoms have been relatively overlooked in this population, although their adverse effects on morbidity are well established in other chronic disease populations. Recent Advances: Inflammation is involved in multiple pathways, which activate brain endothelial and innate immune cells that release proinflammatory cytokines, which produce multiple symptoms known as sickness behaviors. Inflammation-based activation of the kynurenine (KYN) pathway and its metabolites is a mechanism associated with chronic illnesses. Critical Issues: Although putative humoral and neuronal routes have been identified, the specific metabolic variations involved in sickness behaviors in chronic wound patients remain unclear. To improve health outcomes in the chronic wound population, clinicians need to have better understanding of the mechanisms underlying sickness behaviors to provide appropriate treatments. Future Directions: This article presents a synthesis of studies investigating associations between inflammation, metabolic pathways, and sickness behaviors in multiple chronic diseases. The presentation of a theoretical framework proposes a mechanism underlying sickness behaviors in the chronic wound population. By mediating the immune system response, dysregulated metabolites in the KYN pathway may play an important role in sickness behaviors in chronic inflammatory conditions. This framework may guide researchers in developing new treatments to reduce the disease burden in the chronic wound population.

Probiotics Bacillus licheniformis Improves Intestinal Health of Subclinical Necrotic Enteritis-Challenged Broilers

Necrotic enteritis infection poses a serious threat to poultry production, and there is an urgent need for searching effective antibiotic alternatives to control it with the global ban on in-feed antibiotics. This study was conducted to investigate the effects of dietary Bacillus licheniformis replacing enramycin on the growth performance and intestinal health of subclinical necrotic enteritis (SNE)-challenged broilers. In total, 504 1-day-old Arbor Acres male chickens were selected and subsequently assigned into three treatments, including PC (basal diet + SNE challenge), PA (basal diet extra 10 mg/kg enramycin + SNE challenge), and PG (basal diet extra 3.20 × 109 and 1.60 × 109 CFU B. licheniformis per kg diet during 1-21 days and 22-42 days, respectively + SNE challenge). Results showed that B. licheniformis significantly decreased the intestinal lesion scores and down-regulated the Claudin-3 mRNA levels in jejunum of SNE-infected broilers on day 25, but increased the mucin-2 gene expression in broilers on day 42. In addition, B. licheniformis significantly up-regulated the mRNA levels of TRIF and NF-κB of SNE-challenged broilers compared with the control group on day 25 and TLR-4, TRIF compared with the control and the antibiotic group on day 42. The mRNA expression of growth factors (GLP-2 and TGF-β2) and HSPs (HSP60, HSP70, and HSP90) were up-regulated in B. licheniformis supplementary group on days 25 and 42 compared with group PC. LEfSe analysis showed that the relative abundance of Lachnospiraceae_UCG_010 was enriched in the PG group; nevertheless, Clostridiales_vadinBB60 and Rnminococcaceae_NK4A214 were in PA. PICRUSt analysis found that the metabolism of cofactors and vitamins, amino acid metabolism, and carbohydrate metabolism pathways were enriched, whereas energy metabolism, membrane transport, cell motility, and lipid metabolism were suppressed in B. licheniformis-supplemented groups as compared with the PC control. In conclusion, dietary supplementation of B. licheniformis alleviated the intestinal damage caused by SNE challenge that coincided with modulating intestinal microflora structure and barrier function as well as regulating intestinal mucosal immune responses.

Toll receptors remodel epithelia by directing planar-polarized Src and PI3K activity

Toll-like receptors are essential for animal development and survival, with conserved roles in innate immunity, tissue patterning, and cell behavior. The mechanisms by which Toll receptors signal to the nucleus are well characterized, but how Toll receptors generate rapid, localized signals at the cell membrane to produce acute changes in cell polarity and behavior is not known. We show that Drosophila Toll receptors direct epithelial convergent extension by inducing planar-polarized patterns of Src and PI3-kinase (PI3K) activity. Toll receptors target Src activity to specific sites at the membrane, and Src recruits PI3K to the Toll-2 complex through tyrosine phosphorylation of the Toll-2 cytoplasmic domain. Reducing Src or PI3K activity disrupts planar-polarized myosin assembly, cell intercalation, and convergent extension, whereas constitutive Src activity promotes ectopic PI3K and myosin cortical localization. These results demonstrate that Toll receptors direct cell polarity and behavior by locally mobilizing Src and PI3K activity.

Innate Immunity in Diabetic Wound Healing: Focus on the Mastermind Hidden in Chronic Inflammatory

A growing body of evidence suggests that the interaction between immune and metabolic responses is essential for maintaining tissue and organ homeostasis. These interacting disorders contribute to the development of chronic diseases associated with immune-aging such as diabetes, obesity, atherosclerosis, and nonalcoholic fatty liver disease. In Diabetic wound (DW), innate immune cells respond to the Pathogen-associated molecular patterns (PAMAs) and/or Damage-associated molecular patterns (DAMPs), changes from resting to an active phenotype, and play an important role in the triggering and maintenance of inflammation. Furthermore, the abnormal activation of innate immune pathways secondary to immune-aging also plays a key role in DW healing. Here, we review studies of innate immune cellular molecular events that identify metabolic disorders in the local microenvironment of DW and provide a historical perspective. At the same time, we describe some of the recent progress, such as TLR receptor-mediated intracellular signaling pathways that lead to the activation of NF-κB and the production of various pro-inflammatory mediators, NLRP3 inflammatory via pyroptosis, induction of IL-1β and IL-18, cGAS-STING responds to mitochondrial injury and endoplasmic reticulum stress, links sensing of metabolic stress to activation of pro-inflammatory cascades. Besides, JAK-STAT is also involved in DW healing by mediating the action of various innate immune effectors. Finally, we discuss the great potential of targeting these innate immune pathways and reprogramming innate immune cell phenotypes in DW therapy.

The transition from normal lung anatomy to minimal and established fibrosis in idiopathic pulmonary fibrosis (IPF)

BACKGROUND

The transition from normal lung anatomy to minimal and established fibrosis is an important feature of the pathology of idiopathic pulmonary fibrosis (IPF). The purpose of this report is to examine the molecular and cellular mechanisms associated with this transition.

METHODS

Pre-operative thoracic Multidetector Computed Tomography (MDCT) scans of patients with severe IPF (n = 9) were used to identify regions of minimal(n = 27) and established fibrosis(n = 27). MDCT, Micro-CT, quantitative histology, and next-generation sequencing were used to compare 24 samples from donor controls (n = 4) to minimal and established fibrosis samples.

FINDINGS

The present results extended earlier reports about the transition from normal lung anatomy to minimal and established fibrosis by showing that there are activations of TGFBI, T cell co-stimulatory genes, and the down-regulation of inhibitory immune-checkpoint genes compared to controls. The expression patterns of these genes indicated activation of a field immune response, which is further supported by the increased infiltration of inflammatory immune cells dominated by lymphocytes that are capable of forming lymphoid follicles. Moreover, fibrosis pathways, mucin secretion, surfactant, TLRs, and cytokine storm-related genes also participate in the transitions from normal lung anatomy to minimal and established fibrosis.

INTERPRETATION

The transition from normal lung anatomy to minimal and established fibrosis is associated with genes that are involved in the tissue repair processes, the activation of immune responses as well as the increased infiltration of CD4, CD8, B cell lymphocytes, and macrophages. These molecular and cellular events correlate with the development of structural abnormality of IPF and probably contribute to its pathogenesis.

Distinct toll-like receptor signaling in the salamander response to tissue damage

BACKGROUND

Efficient wound healing or pathogen clearance both rely on balanced inflammatory responses. Inflammation is essential for effective innate immune-cell recruitment; however, excessive inflammation will result in local tissue destruction, pathogen egress, and ineffective pathogen clearance. Sterile and nonsterile inflammation operate with competing functional priorities but share common receptors and overlapping signal transduction pathways. In regenerative organisms such as the salamander, whole limbs can be replaced after amputation while exposed to a nonsterile environment. In mammals, exposure to sterile-injury Damage Associated Molecular Patterns (DAMPS) alters innate immune-cell responsiveness to secondary Pathogen Associated Molecular Pattern (PAMP) exposure.

RESULTS

Using new phospho-flow cytometry techniques to measure signaling in individual cell subsets we compared mouse to salamander inflammation. These studies demonstrated evolutionarily conserved responses to PAMP ligands through toll-like receptors (TLRs) but identified key differences in response to DAMP ligands. Co-exposure of macrophages to DAMPs/PAMPs suppressed MAPK signaling in mammals, but not salamanders, which activate sustained MAPK stimulation in the presence of endogenous DAMPS.

CONCLUSIONS

These results reveal an alternative signal transduction network compatible with regeneration that may ultimately lead to the promotion of enhanced tissue repair in mammals.

The program of renal fibrogenesis is controlled by microRNAs regulating oxidative metabolism

Excessive accumulation of extracellular matrix (ECM) is the hallmark of fibrotic diseases. In the kidney, it is the final common pathway of prevalent diseases, leading to chronic renal failure. While cytokines such as TGF-β play a fundamental role in myofibroblast transformation, recent work has shown that mitochondrial dysfunction and defective fatty acid oxidation (FAO), which compromise the main source of energy for renal tubular epithelial cells, have been proposed to be fundamental contributors to the development and progression of kidney fibrosis. MicroRNAs (miRNAs), which regulate gene expression post-transcriptionally, have been reported to control renal fibrogenesis. To identify miRNAs involved in the metabolic derangement of renal fibrosis, we performed a miRNA array screen in the mouse model of unilateral ureteral obstruction (UUO). MiR-150-5p and miR-495-3p were selected for their link to human pathology, their role in mitochondrial metabolism and their targeting of the fatty acid shuttling enzyme CPT1A. We found a 2- and 4-fold upregulation of miR-150-5p and miR-495-5p, respectively, in both the UUO and the folic acid induced nephropathy (FAN) models, while TGF-β1 upregulated their expressions in the human renal tubular epithelial cell line HKC-8. These miRNAs synergized with TGF-β regarding its pro-fibrotic effect by enhancing the fibrosis-associated markers Acta2, Col1α1 and Fn1. Bioenergetics studies showed a reduction of FAO-associated oxygen consumption rate (OCR) in HKC-8 cells in the presence of both miRNAs. Consistently, expression levels of their mitochondrial-related target genes CPT1A, PGC1α and the mitochondrial transcription factor A (TFAM), were reduced by half in renal epithelial cells exposed to these miRNAs. By contrast, we did not detect changes in mitochondrial mass and transmembrane potential (ΔѰm) or mitochondrial superoxide radical anion production. Our data support that miR-150 and miR-495 may contribute to renal fibrogenesis by aggravating the metabolic failure critically involved in tubular epithelial cells, ultimately leading to fibrosis.

Scarred Lung. An Update on Radiation-Induced Pulmonary Fibrosis

Radiation-induced pulmonary fibrosis is a common severe long-time complication of radiation therapy for tumors of the thorax. Current therapeutic options used in the clinic include only supportive managements strategies, such as anti-inflammatory treatment using steroids, their efficacy, however, is far from being satisfactory. Recent studies have demonstrated that the development of lung fibrosis is a dynamic and complex process, involving the release of reactive oxygen species, activation of Toll-like receptors, recruitment of inflammatory cells, excessive production of nitric oxide and production of collagen by activated myofibroblasts. In this review we summarized the current state of knowledge on the pathophysiological processes leading to the development of lung fibrosis and we also discussed the possible treatment options.

Antipseudomonal and Immunomodulatory Properties of Esc Peptides: Promising Features for Treatment of Chronic Infectious Diseases and Inflammation

Persistent infections, such as those provoked by the Gram-negative bacterium Pseudomonas aeruginosa in the lungs of cystic fibrosis (CF) patients, can induce inflammation with lung tissue damage and progressive alteration of respiratory function. Therefore, compounds having both antimicrobial and immunomodulatory activities are certainly of great advantage in fighting infectious diseases and chronic inflammation. We recently demonstrated the potent antipseudomonal efficacy of the antimicrobial peptide (AMP) Esc(1-21) and its diastereomer Esc(1-21)-1c, namely Esc peptides. Here, we confirmed this antimicrobial activity by reporting on the peptides’ ability to kill P. aeruginosa once internalized into alveolar epithelial cells. Furthermore, by means of enzyme-linked immunosorbent assay and Western blot analyses, we investigated the peptides’ ability to detoxify the bacterial lipopolysaccharide (LPS) by studying their effects on the secretion of the pro-inflammatory cytokine IL-6 as well as on the expression of cyclooxygenase-2 from macrophages activated by P. aeruginosa LPS. In addition, by a modified scratch assay we showed that both AMPs are able to stimulate the closure of a gap produced in alveolar epithelial cells when cell migration is inhibited by concentrations of Pseudomonas LPS that mimic lung infection conditions, suggesting a peptide-induced airway wound repair. Overall, these results have highlighted the two Esc peptides as valuable candidates for the development of new multifunctional therapeutics for treatment of chronic infectious disease and inflammation, as found in CF patients.

Inhibiting TGF-[Formula: see text] 1-Mediated Cellular Processes as an Effective Strategy for the Treatment of Pulmonary Fibrosis with Chinese Herbal Medicines

Pulmonary fibrosis (PF) is a chronic and irreversible interstitial lung disease that even threatens the lives of some patients infected with COVID-19. PF is a multicellular pathological process, including the initial injuries of epithelial cells, recruitment of inflammatory cells, epithelial-mesenchymal transition, activation and differentiation of fibroblasts, etc. TGF-[Formula: see text]1 acts as a key effect factor that participates in these cellular processes of PF. Recently, much attention was paid to inhibiting TGF-[Formula: see text]1 mediated cell processes in the treatment of PF with Chinese herbal medicines (CHM), an important part of traditional Chinese medicine. Here, this review first summarized the effects of TGF-[Formula: see text]1 in different cellular processes of PF. Then, this review summarized the recent research on CHM (compounds, multi-components, single medicines and prescriptions) to directly and/or indirectly inhibit TGF-[Formula: see text]1 signaling (TLRs, PPARs, micrRNA, etc.) in PF. Most of the research focused on CHM natural compounds, including but not limited to alkaloids, flavonoids, phenols and terpenes. After review, the research perspectives of CHM on TGF-[Formula: see text]1 inhibition in PF were further discussed. This review hopes that revealing the inhibiting effects of CHM on TGF-[Formula: see text]1-mediated cellular processes of PF can promote CHM to be better understood and utilized, thus transforming the therapeutic activities of CHM into practice.

Extracellular histones stimulate collagen expression in vitro and promote liver fibrogenesis in a mouse model via the TLR4-MyD88 signaling pathway

BACKGROUND

Liver fibrosis progressing to liver cirrhosis and hepatic carcinoma is very common and causes more than one million deaths annually. Fibrosis develops from recurrent liver injury but the molecular mechanisms are not fully understood. Recently, the TLR4-MyD88 signaling pathway has been reported to contribute to fibrosis. Extracellular histones are ligands of TLR4 but their roles in liver fibrosis have not been investigated.

AIM

To investigate the roles and potential mechanisms of extracellular histones in liver fibrosis.

METHODS

In vitro, LX2 human hepatic stellate cells (HSCs) were treated with histones in the presence or absence of non-anticoagulant heparin (NAHP) for neutralizing histones or TLR4-blocking antibody. The resultant cellular expression of collagen I was detected using western blotting and immunofluorescent staining. In vivo, the CCl4-induced liver fibrosis model was generated in male 6-week-old ICR mice and in TLR4 or MyD88 knockout and parental mice. Circulating histones were detected and the effect of NAHP was evaluated.

RESULTS

Extracellular histones strongly stimulated LX2 cells to produce collagen I. Histone-enhanced collagen expression was significantly reduced by NAHP and TLR4-blocking antibody. In CCl4-treated wild type mice, circulating histones were dramatically increased and maintained high levels during the duration of fibrosis-induction. Injection of NAHP not only reduced alanine aminotransferase and liver injury scores, but also significantly reduced fibrogenesis. Since the TLR4-blocking antibody reduced histone-enhanced collagen I production in HSC, the CCl4 model with TLR4 and MyD88 knockout mice was used to demonstrate the roles of the TLR4-MyD88 signaling pathway in CCl4-induced liver fibrosis. The levels of liver fibrosis were indeed significantly reduced in knockout mice compared to wild type parental mice.

CONCLUSION

Extracellular histones potentially enhance fibrogenesis via the TLR4-MyD88 signaling pathway and NAHP has therapeutic potential by detoxifying extracellular histones.

The liver matrisome - looking beyond collagens

The extracellular matrix (ECM) is a diverse microenvironment that maintains bidirectional communication with surrounding cells to regulate cell and tissue homeostasis. The classical definition of the ECM has more recently been extended to include non-fibrillar proteins that either interact or are structurally affiliated with the ECM, termed the 'matrisome.' In addition to providing the structure and architectural support for cells and tissue, the matrisome serves as a reservoir for growth factors and cytokines, as well as a signaling hub via which cells can communicate with their environment and vice-versa. The matrisome is a master regulator of tissue homeostasis and organ function, which can dynamically and appropriately respond to any stress or injury. Failure to properly regulate these responses can lead to changes in the matrisome that are maladaptive. Hepatic fibrosis is a canonical example of ECM dyshomeostasis, leading to accumulation of predominantly collagenous ECM; indeed, hepatic fibrosis is considered almost synonymous with collagen accumulation. However, the qualitative and quantitative alterations of the hepatic matrisome during fibrosis are much more diverse than simple accumulation of collagens and occur long before fibrosis is histologically detected. A deeper understanding of the hepatic matrisome and its response to injury could yield new mechanistic insights into disease progression and regression, as well as potentially identify new biomarkers for both. In this review, we discuss the role of the ECM in liver diseases and look at new "omic" approaches to study this compartment.

Macrophage polarization in innate immune responses contributing to pathogenesis of chronic kidney disease

Chronic kidney disease (CKD) is characterized by inflammation, injury and fibrosis. Dysregulated innate immune responses mediated by macrophages play critical roles in progressive renal injury. The differentiation and polarization of macrophages into pro-inflammatory 'M1' and anti-inflammatory 'M2' states represent the two extreme maturation programs of macrophages during tissue injury. However, the effects of macrophage polarization on the pathogenesis of CKD are not fully understood. In this review, we discuss the innate immune mechanisms underlying macrophage polarization and the role of macrophage polarization in the initiation, progression, resolution and recurrence of CKD. Macrophage activation and polarization are initiated through recognition of conserved endogenous and exogenous molecular motifs by pattern recognition receptors, chiefly, Toll-like receptors (TLRs), which are located on the cell surface and in endosomes, and NLR inflammasomes, which are positioned in the cytosol. Recent data suggest that genetic variants of the innate immune molecule apolipoprotein L1 (APOL1) that are associated with increased CKD prevalence in people of African descent, mediate an atypical M1 macrophage polarization. Manipulation of macrophage polarization may offer novel strategies to address dysregulated immunometabolism and may provide a complementary approach along with current podocentric treatment for glomerular diseases.

Dexmedetomidine-mediated regulation of miR-17-3p in H9C2 cells after hypoxia/reoxygenation injury

Patients with heart disease often suffer from ischemia, which can be treated by reperfusion. However, this treatment can lead to the development of ischemia/reperfusion (I/R) injury, an inflammatory condition that can cause further heart damage. Dexmedetomidine (Dex), an α₂-adrenoceptor agonist, and the microRNA (miR)-17-3p, have both been suggested to alleviate I/R injury and cardiac tissue inflammation. The aim of the present study was to investigate whether Dex and miR-17-3p could act together to prevent I/R injury. H9C2 cells, a myoblast cell line used as a model of rat cardiomyocytes, were cultured in a hypoxic environment for 3 h, and then reoxygenated for 3 h. This hypoxia/reoxygenation (H/R) was used to model I/R. Cell Counting kit-8 was used to determine cell viability and an annexin V-FITC/propidium iodide apoptosis kit used to analyze cell apoptosis. A dual luciferase reporter assay was used to determine the interaction between miR-17-3p and toll-like receptor 4 (TLR4). Western blotting and reverse transcription-quantitative PCR were used to determine protein levels and mRNA expression of TLR4 and galectin-3. A concentration of 0.1-10 µmol/l Dex attenuated H/R injury, which was accompanied by increased miR-17-3p levels. Additionally, the inhibition of miR-17-3p exacerbated H/R injury and reduced the effect of Dex on H/R injury. H/R led to an increased galectin-3 level compared with that in control cells, and Dex or miR-17-3p inhibitor did not markedly affect the level of galectin-3, indicating that Dex alleviated the effects of I/R injury through other pathways. Inhibition of miR-17-3p in Dex-induced H9C2 cells during H/R increased the expression of inflammatory mediators including tumor necrosis factor-α, interleukin (IL)-6, IL-1β and phosphorylated NFκB subunit p65, while Dex reduced the H/R-induced expression of these inflammatory mediators. Inhibition of TLR4 also attenuated H/R injury. In summary, the findings of the present study indicated that Dex reduced H/R injury in H9C2 cell via the modulation of inflammatory signaling pathways, and these inflammatory factors could be regulated by miR-17-3p.

Lipopolysaccharides modulate intestinal epithelial permeability and inflammation in a species-specific manner

Patients presenting with Inflammatory bowel disease have been shown to exhibit an altered microbiome in both Crohn's disease and Ulcerative colitis. This shift in the microbial content led us to question whether several of these microbes are important in inflammatory processes present in these diseases and more specifically whether lipopolysaccharides from the gram-negative cell wall differentially stimulates resident cells. We, therefore, investigated the possible contribution of five major species of gram-negative bacteria found to be altered in presence during disease progression and evaluate their pathogenicity through LPS. We demonstrated that LPS from these different species had individual capacities to induce NF-κB and pro-inflammatory IL-8 production from HEK-TLR4 cells in a TLR4 dependent manner. Additional work using human intestinal colonic epithelial cell monolayers (Caco-2) demonstrated that the cells responded to the serotype specific LPS in a distinct manner, inducing many inflammatory mediators such as TNF-α and IL-10 in significantly altered proportions. Furthermore, the permeability of Caco-2 monolayers, as a test for their ability to alter intestinal permeability, was also differentially altered by the serotype specific LPS modulating trans-epithelial electrical resistance, small molecule movement, and tight junction integrity. Our results suggest that specific species of bacteria may be potentiating the pathogenesis of IBD and chronic inflammatory diseases through their serotype specific LPS responses.

Elucidation of molecular pathways responsible for the accelerated wound healing induced by a novel fibrous chitin dressing

Fibrous chitin dressing (FCD) prepared from a NaOH-urea aqueous solution of chitin via a physical process was used to study its effect on wound healing using a full-thickness cutaneous wound model in rats and mice. It was demonstrated that wounds in rats covered with the FCD showed faster collagen (especially type I collagen) growth and speedier healing than those with Gauze (12 days versus 16 days). The ability of FCD to promote wound healing was also observed on wild-type (WT) mice. For MyD88-knockout mice, however, FCD displayed no beneficial but an adverse effect on wound healing: the healing time for wounds treated with FCD was even longer than those treated with gauze. Importantly, in vivo studies indicated that FCD-treated mice, compared to gauze-treated ones, exhibited markedly higher expressions of MyD88, IKBα, TGF-β, P-TβR II, TβR II and P-Smad2/3 in wild-type mice. For MyD88 knockout mice, however, the expressions of those molecules were inhibited and lowered in FCD-treated ones than those treated with gauze. In vitro studies confirmed that chitin increased the expression of TGF-β, P-TβRII and P-Smad2/3 while the expressions of those molecules were significantly inhibited with CD14 antibody (p < 0.05). These results indicated that FCD accelerated wound healing through a MyD88-dependent pathway, followed by a TGF-β/Smad pathway. This work not only demonstrated the superior wound healing effect of chitin-derived dressing, but also provided for the first time the underlying molecular mechanism, further establishing chitin as an important biomedical material for potential clinical applications.

African green monkeys avoid SIV disease progression by preventing intestinal dysfunction and maintaining mucosal barrier integrity

Unlike HIV infection, SIV infection is generally nonpathogenic in natural hosts, such as African green monkeys (AGMs), despite life-long high viral replication. Lack of disease progression was reportedly based on the ability of SIV-infected AGMs to prevent gut dysfunction, avoiding microbial translocation and the associated systemic immune activation and chronic inflammation. Yet, the maintenance of gut integrity has never been documented, and the mechanism(s) by which gut integrity is preserved are unknown. We sought to investigate the early events of SIV infection in AGMs, specifically examining the impact of SIVsab infection on the gut mucosa. Twenty-nine adult male AGMs were intrarectally infected with SIVsab92018 and serially sacrificed at well-defined stages of SIV infection, preramp-up (1-3 days post-infection (dpi)), ramp-up (4-6 dpi), peak viremia (9-12 dpi), and early chronic SIV infection (46-55 dpi), to assess the levels of immune activation, apoptosis, epithelial damage and microbial translocation in the GI tract and peripheral lymph nodes. Tissue viral loads, plasma cytokines and plasma markers of gut dysfunction were also measured throughout the course of early infection. While a strong, but transient, interferon-based inflammatory response was observed, the levels of plasma markers linked to enteropathy did not increase. Accordingly, no significant increases in apoptosis of either mucosal enterocytes or lymphocytes, and no damage to the mucosal epithelium were documented during early SIVsab infection of AGMs. These findings were supported by RNAseq of the gut tissue, which found no significant alterations in gene expression that would indicate microbial translocation. Thus, for the first time, we confirmed that gut epithelial integrity is preserved, with no evidence of microbial translocation, in AGMs throughout early SIVsab infection. This might protect AGMs from developing intestinal dysfunction and the subsequent chronic inflammation that drives both HIV disease progression and HIV-associated comorbidities.

Toll-Like Receptor 5 Signaling Ameliorates Liver Fibrosis by Inducing Interferon β-Modulated IL-1 Receptor Antagonist in Mice

Bacterial flagellin, recognized by cell surface of Toll-like receptor (TLR) 5, is a potent activator of many types of cells, leading to the activation of innate or adaptive immunity, which are pivotal in regulating fibrotic process. However, the exact role of TLR5 signaling in hepatic fibrogenesis remains unclear, and this study aims to elucidate its underlying mechanisms. Flagellin was injected to hepatotoxin- and cholestasis-induced liver fibrosis murine models. Flagellin-induced TLR5 activation significantly decreased the severity of liver fibrosis. Interestingly, the expression levels of IL-1 receptor antagonist (IL1RN) and interferon (IFN)β markedly increased in fibrotic livers on flagellin treatment. Consistently, in vivo activation of TLR5 signaling markedly increased IFNβ and IL1RN expression in the livers. Notably, flagellin injection significantly exacerbated the severity of liver fibrosis in IFN-α/β receptor 1 (IFNAR1) knockout mice. Furthermore, hepatic expression of IL1RN in the fibrotic livers of IFNAR1 knockout mice was significantly lower than those of wild-type mice. In support of these findings, flagellin-mediated IL1RN production is not sufficient to alleviate the severity of hepatic fibroinflammatory responses in IFNAR1-deficient milieu. Finally, hepatic stellate cells treated with IL1RN had significantly decreased cellular activation and its associated fibrogenic responses. Collectively, manipulation of TLR5 signaling may be a promising therapeutic strategy for the treatment of liver fibrosis.

Effects of Pristine C60 Fullerenes on Liver and Pancreas in α-Naphthylisothiocyanate-Induced Cholangitis

BACKGROUND

A significant role in pathogenesis of cholangitis is attributed to excessive reactive oxygen species production and oxidative stress. Therefore, antioxidants could be promising therapeutics.

AIMS

The effects of powerful free radical scavenger C₆₀ fullerene on hepatic and pancreatic manifestations of acute and chronic cholangitis in rats were aimed to be discovered.

METHODS

Acute (AC, 3 days) and chronic (CC, 28 days) cholangitis models were simulated by single (AC) and 4 weekly (CC) α-naphthylisothiocyanate per os administrations. Pristine C₆₀ fullerene aqueous colloid solution (C₆₀FAS, 0.15 mg/ml, size of aggregates 1.2-100 nm) was administered either per os or intraperitoneally at a dose of 0.5 mg/kg C₆₀ fullerene daily (AC) and every other day (CC). Prednisolone was used as a reference. Liver and pancreas autopsies were analyzed, and blood serum biochemical markers were measured. Pan-cytokeratin expression in HepG2 cells was assessed after 48-h incubation with C₆₀FAS.

RESULTS

On AC, C₆₀FAS normalized elevated bilirubin, alkaline phosphatase, and triglycerides, diminished fibrotic alterations in liver, and improved pancreas state when applied by both ways. Additionally, C₆₀FAS per os significantly reduced the signs of inflammation in liver and pancreas. On CC, C₆₀FAS also mitigated liver fibrosis and inflammation, improved pancreas state, and normalized alkaline phosphatase and triglycerides. The remedy effect of C₆₀FAS was more expressed compared to that of prednisolone on both models. Furthermore, C₆₀FAS inhibited pan-cytokeratin expression in HepG2 cells in a dose-dependent manner.

CONCLUSION

Pristine C₆₀ fullerene inhibits liver inflammation and fibrogenesis and partially improved liver and pancreas state under acute and chronic cholangitis.

Through the lens of hair follicle neogenesis, a new focus on mechanisms of skin regeneration after wounding

Wound-induced hair follicle neogenesis (WIHN) is a phenomenon that occurs in adult mammalian skin, where fully functional hair follicles are regenerated in the center of large full-thickness excisional wounds. Although originally discovered over 50 years ago in mice and rabbits, within the last decade it has received renewed interest, as the molecular mechanism has begun to be defined. This de novo regeneration of hair follicles largely recapitulates embryonic hair development, requiring canonical Wnt signaling in the epidermis, however, important differences between the two are beginning to come to light. TLR3 mediated double stranded RNA sensing is critical for the regeneration, activating retinoic acid signaling following wounding. Inflammatory cells, including Fgf9-producing γ-δ T cells and macrophages, are also emerging as important mediators of WIHN. Additionally, while dispensable in embryonic hair follicle development, Shh signaling plays a major role in WIHN and may be able to redirect cells fated to scarring wounds into a regenerative phenotype. The cellular basis of WIHN is also becoming clearer, with increasing evidence suggesting an incredible level of cellular plasticity. Multiple stem cell populations, along with lineage switching of differentiated cells all contribute towards the regeneration present in WIHN. Further study of WIHN will uncover key steps in mammalian development and regeneration, potentially leading to new clinical treatments for hair-related disorders or fibrotic scarring.

Hyperglycemia acts in synergy with hypoxia to maintain the pro-inflammatory phenotype of macrophages

Diabetic foot ulcers (DFUs) are characterized by a chronic inflammation state which prevents cutaneous wound healing, and DFUs eventually lead to infection and leg amputation. Macrophages located in DFUs are locked in an pro-inflammatory phenotype. In this study, the effect of hyperglycemia and hypoxia on the macrophage phenotype was analyzed. For this purpose, a microarray was performed to study the gene expression profile of macrophages cultivated in a high glucose concentration. Hyperglycemia upregulated the expression of pro-inflammatory cytokines such as TNF-α, IL-1, IL-6, chemokines and downregulated the expression of two receptors involved in phagocytosis (CD 36 and Class B scavenger type I receptors). In addition, eleven anti-apoptotic factors were upregulated whereas three pro-apoptotic genes were downregulated. Subsequently, the contribution of hypoxia and hyperglycemia to chronic inflammation and their potential synergistic effect was evaluated on activated THP-1 derived macrophages. A long term post activation effect (17 hours) was only observed on the upregulation of pro-inflammatory cytokines when hypoxia was combined with a high glucose concentration. In contrast, hyperglycemia and hypoxia did not have any effect on wound healing molecules such as TGF-β1. Taken together, the results show that hyperglycemia acts in synergy with hypoxia to maintain a chronic inflammation state in macrophages.

Gene expression profiling distinguishes prefibrotic from overtly fibrotic myeloproliferative neoplasms and identifies disease subsets with distinct inflammatory signatures

The Philadelphia chromosome-negative myeloproliferative neoplasms (MPN) share similar molecular characteristics in that they frequently harbor hotspot mutations in JAK2, CALR or MPL, leading to activated JAK/STAT signaling. However, these MPN have distinct symptoms, morphology, and natural histories, including different tendencies to progress to fibrosis. Although the role of inflammation in tissue fibrosis is well recognized, inflammatory gene expression in bone marrows involved by MPN has been understudied. We analyzed the expression of inflammatory genes by directly measuring RNA transcript abundance in bone marrow biopsies of 108 MPN patients. Unsupervised analyses identified gene expression patterns that distinguish prefibrotic (grade 1–2) MPN from overtly fibrotic (grade 2–3) MPN with high sensitivity and specificity in two independent cohorts. Furthermore, prefibrotic and overtly fibrotic MPN are separable into subsets with different activities in biological pathways linked to inflammation, including cytokines, chemokines, interferon response, and toll-like receptor signaling. In conclusion, this study demonstrates that MPN with overt fibrosis is associated with significant inflammatory gene upregulation in the bone marrow, revealing potential roles for multiple pro-inflammatory signaling networks in the development of myelofibrosis and suggesting potential therapeutic mechanisms to alleviate this process in the bone marrow microenvironment.