Epithelial antimicrobial defence of the skin and intestine

Helminth reshapes host gut microbiota and immunoregulation by deploying an antimicrobial program of innate immunity

Helminths can manipulate their host's gut microbiota, with the expansion of the lactobacilli population being a common feature. This process profoundly influences host immunoregulation, yet the underlying mechanisms remain almost unknown. Using a tissue-dwelling helminth model (larval Echinococcus multilocularis) while validating key findings from other helminth infections, we show that helminths harness the antibacterial program of host innate immunity to transform the host gut microbiome and control gut microbiota-mediated immunity. Using multifaceted techniques, we elucidate that cathelicidin-related antimicrobial peptide (CRAMP), derived from the expanded CD11b+CD206+ macrophages rather than the intestinal epithelial cells, is the key component that enters into the gut ecological system and enhances the fitness of Lactobacillus by selectively killing gram-negative microbes like enterobacteria. Furthermore, through in vitro cell culturing and in vivo dietary intervention experiments, we demonstrate that this regulation from innate immunity is boosted via toll-like receptor signaling by helminth's secretory products, which could be sufficiently tuned down by dietary vitamin D through its receptor and cyp27b1. Importantly, using microbiota-targeted treatment methods, we prove that this signaling bolsters gut microbiota-mediated host intestinal Foxp3+ Treg cell expansion and parasite survival and that therapies targeting this signaling are effective in treating infection. We outline a dietary micronutrient-dependent mechanism by which helminths leverage host innate immunity to edit the host gut microbiome and thereby control immunosuppression precisely.

AhR Activation Transcriptionally Induces Anti-Microbial Peptide Alpha-Defensin 1 Leading to Reversal of Gut Microbiota Dysbiosis and Colitis

Alpha-defensin 1 is a small antimicrobial peptide that acts as the first line of defense against pathogens. It is induced following microbial cues and inflammatory signals in neutrophils and Paneth cells in the small intestine, which suggests that it plays a role in microbial homeostasis in the gut. The gut microbial products also serve as ligands for the aryl hydrocarbon receptor (AhR), an environmental sensor. In the current study, we investigated if there is any crosstalk between AhR and alpha-defensin 1. Interestingly, we found a positive correlation between AhR and alpha-defensin 1 protein levels in ileal tissues from active Crohn's' (CD) patients and epithelial cells (IECs) from multiple models of murine colitis. In vitro downregulation of AhR led to inhibition of α-defensin 1, while activation of AhR induced α-defensin 1 in IECs. AhR directly targeted the dioxin response element 3 (DRE3) region on the α-defensin 1 promoter in IECs. AhR-mediated induction of α-defensin 1 in colitis mice reversed the gut microbial dysbiosis and alleviated colitis. Our data identify a novel signaling pathway in which AhR acts as a transcription factor for α-defensin 1, leading to regulation of homeostasis between gut microbiota, intestinal mucosa, and mucosal immunity.

Polyaminoglycoside nanosystem expressing antimicrobial peptides for multistage chronic wound management

Chronic wounds are difficult to heal due to pathogenic microbial colonization and dysregulation of healing cascades, necessitating novel therapeutic strategies. This study developed a multifunctional nanosystem by integrating the antimicrobial peptide LL37 with cationic polyaminoglycoside (SS-HPT), constructing a self-sustaining "AMP factory" to achieve multi-stage modulation of the wound healing. Validation through cell-level experiments and in vivo dual models (mechanical injury and bacterial infection) in immunocompromised rats demonstrated the system's unique dual intracellular-extracellular pathogen-killing capability, significantly accelerating the wound healing process. Transcriptomic analysis revealed that its mechanism involves the dual effects of suppressing pro-inflammatory factor expression and activating tissue repair pathways. Histological evidence confirmed that the system promotes angiogenesis, enhances re-epithelialization rates, and guides orderly collagen fiber deposition. This nanosystem, combining efficient AMP delivery and integrated therapeutic strategies, achieves three-dimensional synergy in microbial clearance, immune microenvironment regulation, and tissue matrix remodeling, providing theoretical and technical foundations for a paradigm shift in chronic wound treatment.

Immune modulation for the patterns of epithelial cell death in inflammatory bowel disease

Inflammatory bowel disease (IBD) is an inflammatory disease of the intestine whose primary pathological presentation is the destruction of the intestinal epithelium. The intestinal epithelium, located between the lumen and lamina propria, transmits luminal microbial signals to the immune cells in the lamina propria, which also modulate the intestinal epithelium. In IBD patients, intestinal epithelial cells (IECs) die dysfunction and the mucosal barrier is disrupted, leading to the recruitment of immune cells and the release of cytokines. In this review, we describe the structure and functions of the intestinal epithelium and mucosal barrier in the physiological state and under IBD conditions, as well as the patterns of epithelial cell death and how immune cells modulate the intestinal epithelium providing a reference for clinical research and drug development of IBD. In addition, according to the targeting of epithelial apoptosis and necroptotic pathways and the regulation of immune cells, we summarized some new methods for the treatment of IBD, such as necroptosis inhibitors, microbiome regulation, which provide potential ideas for the treatment of IBD. This review also describes the potential for integrating AI-driven approaches into innovation in IBD treatments.

Cutaneous T cell immunity

The skin is the primary barrier against environmental insults, safeguarding the body from mechanical, chemical and pathogenic threats. The frequent exposure of the skin to environmental challenges requires an immune response that incorporates a sophisticated combination of defenses. Tissue-resident lymphocytes are pivotal for skin immunity, working in tandem with commensal bacteria to maintain immune surveillance and homeostasis, as well as participating in the pathogenesis of several skin diseases. Indeed, it has been estimated that the human skin harbors nearly twice as many T cells as found in the circulation. Effective treatment of skin diseases and new therapy development require a thorough understanding of the complex interactions among skin tissue, immune cells and the microbiota, which together regulate the skin's immune balance. This Review explores the latest developments and understanding of this critical barrier organ, with a specific focus on the role of skin-resident T cells.

The Role of Bile Acid in Immune-Mediated Skin Diseases

Immune-mediated skin disorders arise from dysfunctional immune responses, instigating inflammatory dermatoses and a reduced quality of life. The complex pathogenesis likely involves genetic risks, environmental triggers and aberrant immune activation. An emerging body of evidence suggests that bile acid disturbances may critically promote immune pathology in certain skin conditions. Bile acids synthesised from cholesterol regulate nutrient metabolism and immune cell function via nuclear receptors and G protein-coupled receptors (GPCRs). Altered bile acid profiles and receptor expression have been identified in psoriasis, atopic dermatitis (AD) and autoimmune blistering diseases. Disruptions in bile acid signalling affect the inflammatory and metabolic pathways linked to these disorders. Targeting components of the bile acid axis represents a promising therapeutic strategy. This review elucidates the intricate links between bile acid homeostasis and immune dysfunction in inflammatory skin diseases, synthesising evidence that targeting bile acid pathways may unlock innovative therapeutic avenues. This study compiles clinical and experimental data revealing disrupted bile acid signalling and composition in various immune-mediated dermatoses, highlighting the emerging significance of bile acids in cutaneous immune regulation.

Antimicrobial Peptide Signaling in Skin Diseases

Antimicrobial peptides (AMPs) are important innate immune molecules at microbe-host interfaces. The biophysical properties of AMPs that facilitate direct killing of microbes have been extensively reviewed. In this article, we focus on how AMPs perform immunomodulatory functions through interaction with host receptors on epithelial, immune, and neuronal cell types. We summarize the current knowledge of known AMPs in the skin, the receptors that respond to AMPs, and the downstream intracellular signaling pathways. In the end, we discuss the roles of AMP signaling systems in skin diseases.

Discovery and Optimisation of Novel Bombinin-Derived Peptides from Bombina variegata against Staphylococcus aureus

Amphibian skin-secreted antimicrobial peptides (AMPs) have garnered significant attention for their excellent biological activity and low propensity for drug resistance over the past 40 years. Bombinins and bombinin H, two classes of AMPs isolated from the skin secretions of Bombina species, demonstrate strong antimicrobial activity against broad-spectrum microorganisms. In this study, two novel peptides, bombinin-like peptide 7S and bombinin-H2L, were identified from the toad, Bombina variegata. While both peptides exhibited broad-spectrum antimicrobial activity, they also showed relatively high cytotoxicity. To explore the structure-activity relationship and enhance therapeutic potential, bombinin-H2L, which displayed stronger average antimicrobial activity, was used as a template. With the aid of bioinformatics analysis, a series of bombinin-H2L analogues were designed by increasing the net positive charges and/or adjusting the amphiphilicity of the parent peptide. Among these analogues, [Arg8, 15]BH2L and [Lys7, 8]BH2L demonstrated high therapeutic efficacy and specificity toward clinically isolated, drug-resistant Staphylococcus aureus strains in both in vitro and ex vivo tests. Their notable biosafety profiles, sensitivity to diverse environments, and ability to disrupt biofilms highlight their potential for further development. Additionally, studies on the mechanism of [Arg8, 15]BH2L and [Lys7, 8]BH2L revealed a membrane-targeted antimicrobial mechanism, with its antibacterial function exerted by disrupting the integrity of bacterial membranes. These findings provide valuable insights into structural modifications of bombinin H peptides for enhanced activity, and [Arg8, 15]BH2L and [Lys7, 8]BH2L have the potential as promising candidates for novel antibacterial agents in treated bacterial skin infections.

Cathelicidin antimicrobial peptides mediate immune protection in marsupial neonates

Marsupial neonates are born with immature immune systems, making them vulnerable to pathogens. While neonates receive maternal protection, they can also independently combat pathogens, although the mechanisms remain unknown. Using the sugar glider (Petaurus breviceps) as a model, we investigated immunological defense strategies of marsupial neonates. Cathelicidins-a family of antimicrobial peptides expanded in the genomes of marsupials-are highly expressed in developing neutrophils. Sugar glider cathelicidins reside in two genomic clusters, and their coordinated expression is achieved by enhancer sharing within clusters and long-range physical interactions between clusters. Functionally, cathelicidins modulate immune responses and have potent antibacterial effects, sufficient to provide protection in a mouse model of sepsis. Evolutionarily, cathelicidins have a complex history, with marsupials and monotremes uniquely retaining both clusters among tetrapods. Thus, cathelicidins are critical mediators of marsupial immunity, and their evolution may reflect the life history-specific immunological needs of these animals.

There's no place like home: How local tissue microenvironments shape the function of innate lymphoid cells

Innate lymphoid cells (ILC) have emerged as critical immune effectors with key roles in orchestrating the wider immune response. While ILC are relatively rare cells they are found enriched within discrete microenvironments, predominantly within barrier tissues. An emerging body of evidence implicates complex and multi-layered interactions between cell types, tissue structure and the external environment as key determinants of ILC function within these niches. In this review we will discuss the specific components that constitute ILC-associated microenvironments and consider how they act to determine health and disease. The development of holistic, integrated models of ILC function within complex tissue environments will inform new understanding of the contextual cues and mechanisms that determine the protective versus disease-causing roles of this immune cell family.

Harnessing from Nature - Evolving Potential of Antimicrobial Peptide

Antimicrobial peptides (AMPs) are recognized as one of the most ancient components of innate immunity, playing a pivotal role as the first line of host defense systems. These evolutionarily conserved molecules have been identified in various organisms, from prokaryotes to humans. AMPs establish a delicate balanced relationship between host and microbes, by simultaneously regulating the biological activities of pathogens and commensal microbes. Given the escalating global concern over antibiotic resistance, there is an urgent need to explore alternative strategies to combat challenging infectious diseases. AMPs have emerged as promising candidates employed in clinical practice due to their sustainable bactericidal properties. Witnessed by deep understanding of AMPs actions toward host and bacteria, the potential applications of AMPs extend far beyond infection control. Emerging developments harnessed natural capabilities of AMPs to optimize their roles in modulating host signaling, treating diverse diseases, advancing biosensing and bioimaging technologies. In this Concept paper, we provide a comprehensive overview of the diversity and properties of AMPs. Additionally, we elaborate on the mechanisms underlying AMP activity and bacterial responses counteracting AMPs' functions. Most importantly, we discuss potential biomedical applications of AMPs and offer perspectives on their future development.

Obesity and insulinopenic type 2 diabetes differentially impact, bone phenotype, bone marrow adipose tissue, and serum levels of the cathelicidin-related antimicrobial peptide in mice

Obesity is a risk factor of developing type 2 diabetes (T2D) and metabolic complications, through systemic inflammation and insulin resistance. It has also been associated with increased bone marrow adipocytes along with increased bone fragility and fracture risk. However, the differential effects of obesity and T2D on bone fragility remain unclear. The cathelicidin-related antimicrobial peptide (CRAMP) is a multifunctional modulator of the innate immunity that has emerged as biomarker of cardiometabolic diseases. The aims of this study were i) to assess the differential impact between hyperinsulinemic obesity versus insulinopenic T2D, on bone phenotype and bone marrow adipose tissue (BMAT), and ii) to analyse the link with CRAMP expression and its circulating levels in the context of obesity and T2D. We used C57BL/6 J male mice models of obesity induced by high-fat diet (HFD), and of insulinopenic T2D induced by streptozotocin (STZ) treatment combined with HFD, reflecting the metabolic heterogeneity of the diseases. As compared to low-fat diet (LFD) control group after 16 weeks of feeding, the HFD mice exhibit a significant weight gain, moderate hyperglycaemia, impaired glucose tolerance and insulin sensitivity, and significant increase in serum insulin levels. This hyperinsulinemic obesity led to decreased trabecular (Tb.Th) and cortical thickness (Ct.Th) in the tibia, associated with significant BMAT expansion, in addition to increased subcutaneaous (SCAT) and visceral adipose tissue (VAT). No changes were observed in the circulating levels of CRAMP peptide neither in other bone parameters. While, STZ treatment in HFD/STZ group induced a more severe hyperglycaemia, glucose intolerance and insulin resistance, and hypoinsulinemia. We also observed a negative effect on the expansion of both SCAT and VAT, as well as lower increase in BMAT as compared to HFD group. However, these mice with insulinopenic T2D exhibit early decrease in trabecular number (Tb.N) in proximal tibia, progressively from 8 to 16 weeks of protocol, and impaired femoral biomechanical stiffness. These alterations are also accompanied with decreased circulating levels of the CRAMP peptide in the HFD/STZ mice. The CRAMP mRNA levels decreased in VAT of both HFD and HFD/STZ groups. Overall, these results provide novel insights into the differential negative impact of obesity versus T2D on bone microenvironment, and suggest a link between hyperglycaemia-induced bone quality alterations during insulinopenia, and impaired regulation of the cathelicidin peptide of the innate immunity. Further investigations are needed to elucidate this relationship.

Causal association of the skin microbiome with human infertility: insights from a bidirectional two-sample Mendelian randomization

Infertility is a disorder characterized by the inability to achieve a clinical pregnancy after 12 months of regular and unprotected sexual activity. Affecting 8-12% of the global population, with the continuous progress of microbial research in recent years, a variety of microorganisms may be associated with the onset of infertility. We therefore used a two-sample MR Analysis to investigate the association between skin microbes and infertility. we used preprocessed exposure data to correlate infertility measures (infertility in women, associated with anovulation; Female infertility, cervical infertility, vaginal infertility, other infertility or unknown causes; Female infertility, fallopian tube origin; ED; Based on this, the positive results were subjected to horizontal pleiotropy analysis and heterogeneity analysis. Finally, Steiger test was performed to confirm the absence of reverse causality. The data used in this study were obtained from the published GWAS data sets. skin microbiota from the study conducted by Moitinho-Silva et al., and the exposure from the Finn. In this study, we found a positive causal association between Lactobacillales, Clostridiales, Pseudomonadales, and Moraxellaceae and female infertility and anovulation by MR Analysis of two samples. Enhydrobacter, Betaproteobacteria have a negative causal association with female infertility and anovulation. Lactobacillales and Alphaproteobacteria had positive causal association with female infertility, cervical infertility, vaginal infertility, other infertility or unknown causes. There was a negative causal association between Haemophilus and female infertility, cervical infertility, vaginal infertility, other infertility or unknown causes. Alphaproteobacteria are positively correlated with female infertility and fallopian tube origin. Bacteroidetes is negatively correlated with female infertility and fallopian tube origin. Rhodobacteraceae, Clostridiales and Flavobacteriaceae had a negative causal association with male infertility. Corynebacterium had a positive causal association with ED, and Micrococcus had a negative causal association with ED. Our study reveals a causal association between skin microbiota and infertility, and provides a theoretical basis for the inclusion of skin microbiota in the prevention and treatment of infertility. To the best of our knowledge, our study is the first MR Analysis to explore the potential causal association between skin microbiota and infertility. On this basis, we make a reasonable hypothesis that skin microbes cause infertility, and propose possible mechanisms. Our research contributes to the prevention and treatment of clinical infertility.

The Role of Beta-Defensin 2 in Preventing Preterm Birth with Chorioamnionitis: Insights into Inflammatory Responses and Epithelial Barrier Protection

Antimicrobial peptides, such as beta-defensin 2 (BD2), are vital in controlling infections and immune responses. In this study, we investigated the expression and role of BD2 in the amniotic membrane and human amniotic epithelial cells (hAECs) from patients with preterm birth and chorioamnionitis, focusing on its regulation of inflammatory cytokines and its protective effect on the epithelial barrier. Our results show increased BD2 expression in chorioamnionitis, and Lipopolysaccharide (LPS)-induced inflammation increased BD2 release from hAECs in a dose- and time-dependent manner. BD2 treatment effectively modulated the inflammatory response by reducing pro-inflammatory cytokines (IL-6, IL-1β) and enhancing the release of the anti-inflammatory cytokine IL-10. Additionally, BD2 helps preserve epithelial barrier integrity by restoring E-cadherin expression and reducing Snail expression in inflamed hAECs. In an LPS-induced preterm birth mouse model, BD2 treatment delayed preterm delivery and reduced inflammatory cytokine levels. These results suggest that BD2 plays a protective role in preventing preterm birth by regulating inflammation and maintaining epithelial barrier function, highlighting its therapeutic potential for inflammation-related preterm birth.

Effects of Dietary Vitamin A on the Growth Performance, Nonspecific Immune Response, Shell Microbiota and Red Spotted Disease Resistance of Juvenile Sea Urchin (Strongylocentrotus intermedius)

A 114-day feeding trial was used to investigate the influence of vitamin A (VA) on growth performance, nonspecific immune responses and shell microbiota in juvenile sea urchin (Strongylocentrotus intermedius). Graded levels of VA (0, 4000, 8000, 16,000, 32,000 and 64,000 IU/kg) were added to make six experimental feeds. Each feed was allocated to three parallel tanks of sea urchins (initial weight 0.87 ± 0.05 g and initial test diameter 1.83 ± 0.57 mm). The data revealed that the weight gain rate (WGR) and gonadosomatic index (GSI) rose markedly as VA addition level increased from 0 to 4000 IU/kg and then reached a plateau with further increase of dietary VA levels. As VA addition level increased, nonspecific immune response of S. intermedius first increased and then decreased, with those fed diets with relatively higher addition of VA (32,000 IU/kg) exhibiting significantly greater phagocytic activity (PA) and acid phosphatase (ACP) activities, as well as upregulated expression of several immune-related genes such as tumour necrosis factor α (TNF-α), antimicrobial peptides (AMPs), toll-like receptors (TLRs) and lysozyme (LYZ). The abundance of Firmicutes, Bacteroidota, Bacteroides and Faecalibacterium increased, but that of Proteobacteria and Leucothrix decreased in the shell of S. intermedius as VA addition level increased. The percentage of sea urchins with severe red spotted disease decreased from 64.44% to13.33% as VA addition level increased to 32,000 IU/kg and subsequently increased to 42.22% with further increase of VA addition level. On the contrary, the percentage of sea urchins with mild red spotted disease increased from13.33% to 55.55% as VA addition level increased to 32,000 IU/kg and subsequently decreased to 31.11% with further increase of VA addition level. These results demonstrated that a low addition level of VA (4000 IU/kg) can help S. intermedius achieve ideal growth performance. However, relatively higher addition levels of VA (32,000 IU/kg) enhanced nonspecific immunity and red spotted disease resistance of S. intermedius, which could be accomplished by promoting immune gene expression and optimizing the shell microbiota composition.

Exploring the impact of solar radiation on skin microbiome to develop improved photoprotection strategies

The skin microbiome undergoes constant exposure to solar radiation (SR), with its effects on health well-documented. However, understanding SR's influence on host-associated skin commensals remains nascent. This review surveys existing knowledge on SR's impact on the skin microbiome and proposes innovative sun protection methods that safeguard both skin integrity and microbiome balance. A team of skin photodamage specialists conducted a comprehensive review of 122 articles sourced from PubMed and Research Gateway. Key terms included skin microbiome, photoprotection, photodamage, skin cancer, ultraviolet radiation, solar radiation, skin commensals, skin protection, and pre/probiotics. Experts offered insights into novel sun protection products designed not only to shield the skin but also to mitigate SR's effects on the skin microbiome. Existing literature on SR's influence on the skin microbiome is limited. SR exposure can alter microbiome composition, potentially leading to dysbiosis, compromised skin barrier function, and immune system activation. Current sun protection methods generally overlook microbiome considerations. Tailored sun protection products that prioritize both skin and microbiome health may offer enhanced defense against SR-induced skin conditions. By safeguarding both skin and microbiota, these specialized products could mitigate dysbiosis risks associated with SR exposure, bolstering skin defense mechanisms and reducing the likelihood of SR-mediated skin issues.

The role of the microbiome in allergic dermatitis-related otitis externa: a multi-species comparative review

The external ear canal, characterized by species-specific structural and physiological differences, maintains a hostile environment that prevents microbial overgrowth and foreign body entry, supported by factors such as temperature, pH, humidity, and cerumen with antimicrobial properties. This review combines several studies on the healthy ear canal's structure and physiology with a critical approach to the potential existence of an ear microbiome. We use a comparative multi-species approach to explore how allergic conditions alter the ear canal microenvironment and cerumen in different mammalian species, promoting pathogen colonization. We propose a pathogenetic model in which allergic conditions disrupt the antimicrobial environment of the EEC, creating circumstances favorable for facultative pathogenic micro-organisms like Staphylococcus and Malassezia species, leading to otitis externa (OE). A better understanding of the underpinning mechanisms may lead to innovative approaches to disease mitigation.

Cathelicidin antimicrobial peptide expression in neutrophils and neurons antagonistically modulates neuroinflammation

Multiple sclerosis (MS) is an autoimmune disease that affects the CNS, the pathophysiology of which remains unclear and for which there is no definitive cure. Antimicrobial peptides (AMPs) are immunomodulatory molecules expressed in various tissues, including the CNS. Here, we investigated whether the cathelicidin-related AMP (CRAMP) modulated the development of experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. We showed that, at an early stage, CNS-recruited neutrophils produced neutrophil extracellular traps (NETs) rich in CRAMP that were required for EAE initiation. NET-associated CRAMP stimulated IL-6 production by dendritic cells via the cGAS/STING pathway, thereby promoting encephalitogenic Th17 response. However, at a later disease stage, neurons also expressed CRAMP that reduced EAE severity. Camp knockdown in neurons led to disease exacerbation, while local injection of CRAMP1-39 at the peak of EAE promoted disease remission. In vitro, CRAMP1-39 regulated the activation of microglia and astrocytes through the formyl peptide receptor (FPR) 2. Finally, administration of butyrate, a gut microbiota-derived metabolite, stimulated the expression of neural CRAMP via the free fatty acids receptors 2/3 (FFAR2/3), and prevented EAE. This study shows that CRAMP produced by different cell types has opposing effects on neuroinflammation, offering therapeutic opportunities for MS and other neuroinflammatory disorders.

The Prophylactic Protection of Salmonella Typhimurium Infection by Lentilactobacillus buchneri GX0328-6 in Mice

Salmonellosis is a disease caused by non-typhoid Salmonella, and although some lactic acid bacteria strains have been shown previously to relieve Salmonellosis symptoms, little has been studied about the preventive mechanism of Lentilactobacillus buchneri (L. buchneri) against Salmonella infection in vivo. Therefore, the L. buchneri was fed to C57BL/6 mice for 10 days to build a protective system of mice to study its prevention and possible mechanisms. The results showed that L. buchneri GX0328-6 alleviated symptoms caused by Salmonella typhimurium infection among C57BL/6 mice, including low survival rate, weight loss, increase in immune organ index and hepatosplenomegaly, and modulated serum immunoglobulin levels and intrinsic immunity. Importantly, the L. buchneri GX0328-6 enhanced the mucosal barrier of the mouse jejunum by upregulating the expression of tight junction proteins such as ZO-1, occludins, and claudins-4 and improved absorptive capacity by increasing the length of mouse jejunal villus and the ratio of villus length to crypt depth and decreasing the crypt depth. L. buchneri GX0328-6 reduced the intestinal proliferation and invasion of Salmonella typhimurium by modulating the expression of antimicrobial peptides in the intestinal tract of mice, and reduced intestinal inflammation and systemic spread in mice by downregulating the expression of IL-6 and promoting the expression of IL-10. Furthermore, L. buchneri GX0328-6 increased the relative abundance of beneficial bacteria colonies and decreased the relative abundance of harmful bacteria in the cecum microflora by modulating the microflora in the cecum contents.

Bactogram: Spatial Analysis of Bacterial Colonisation in Epidermal Wounds

Skin barrier damage and subsequent development of harmful microbiota contribute to conditions such as wound infections, atopic dermatitis and chronic wounds, which impact millions of people globally and pose a significant economic burden on healthcare systems. Established microbial sampling methods, such as swabs and tissue biopsies, provide limited information on the spatial distribution of bacteria. We here describe a new method that produces a visual map of the distribution of cultivable bacteria, denoted 'Bactogram', across the whole wound and surrounding skin, suitable for image-based quantification. As part of an exploratory endpoint in a clinical trial we applied the Bactogram method to 48 suction blister wounds in 24 healthy volunteers. Bacteria developed in all wounds, predominantly on the skin under the dressing and near wound edges. Two quantification methods, based on visual scoring and image analysis, demonstrated high inter-, and intra-rater agreement and were used to characterise bacterial re-colonisation during epidermal wound healing. We also demonstrated proof of concept that the method can be used with chromogenic agar to enable spatial identification of pathogenic bacterial species, such as Staphylococcus aureus. In conclusion, this study introduces a simple method for sampling bacteria over large areas and generating a bacterial map that can identify spatial variations in bacterial composition and abundance in skin and wound conditions. Trial Registration: ClinicalTrials.gov identifier: NCT05378997.

Osteopontin Depletion in Nonhematopoietic Cells Improves Outcomes in Septic Mice by Enhancing Antimicrobial Peptide Production

Osteopontin (Opn) depletion can improve septic outcomes, but the underlying mechanism remains unknown. In this study, we demonstrated that nonhematopoietic but not hematopoietic Opn depletion improved septic outcomes. When compared with wild type mice, cohoused Opn-/- mice displayed enhanced production of antibacterial peptides (AMPs), decreased bacterial loads, and a distinct bacterial composition of gut microbiota. Fecal microbiota transplantation and OPN neutralization assay showed that Opn depletion could reduce bacterial loads and improve septic inflammation. By employing an intestinal organoid culture system, we proved that OPN neutralization in wild type organoids could inactivate AKT and decrease FOXO3a phosphorylation, resulting in enhanced AMP production, whereas OPN treatment in OPN-deficient organoids could activate AKT and increase FOXO3a phosphorylation, leading to reduced AMP production. Our findings identified OPN as a novel regulatory factor of AMP production to modulate bacterial loads and composition of gut microbiota, in turn affecting sepsis outcomes.

The Central Roles of Keratinocytes in Coordinating Skin Immunity

The function of keratinocytes (KCs) to form a barrier and produce cytokines is well-known, but recent progress has revealed many different roles for KCs in regulation of skin immunity. In this review, we provide an update on the current understanding of how KCs communicate with microbes, immunocytes, neurons, and other cells to form an effective immune barrier. We catalog the large list of genes and metabolites of KCs that participate in host defense and discuss the mechanisms of immune crosstalk, addressing how KCs simultaneously form a physical barrier, communicate with fibroblasts, and control immune signals. Overall, the signals sent and received by KCs are an exciting group of therapeutic targets to explore in the treatment of dermatologic disorders.

A multiplex microbial profiling system for the identification of the source of body fluid and skin samples

Determining the source of body fluids is crucial in forensic investigations, as it provides valuable information about suspects and the nature of the crime. Microbial markers that trace the source of tissues and body fluids based on site specificity and temporal stability are often used effectively for this purpose. In this study, a multiplex system comprising seven microbial markers (Finegoldia magna, Corynebacterium tuberculostearicum, Cutibacterium acnes, Haemophilus parainfluenzae, Streptococcus oralis, Prevotella melaninogenica and Faecalibacterium prausnitzii) was developed to distinguish between skin, saliva, and feces samples. Based on these markers, the system produces electropherograms that are specific for each sample type. We collected 492 samples from six different skin sites (palm, antecubital crease, inguinal crease, cheek, upper back, and toe web space), the buccal mucosa, and stool were collected to further test the system. Beta diversity analysis revealed distinct clustering among the three sample groups. Additionally, skin microenvironment cluster analysis was used to identify skin sites accurately. This analysis classified skin samples into four distinct microenvironments: dry, moist, oily, and foot. Finally, we established a machine learning prediction model based on random forest regression to identify the skin microenvironment, achieving an overall prediction accuracy of 79 %. The multiplex system developed in this study accurately identifies the sources of body fluids, and the skin microenvironment. These findings offer new insights into the application of microbial markers in forensic science.

Nanopore-based full-length transcriptome sequencing of the skin in Pseudopleuronectes yokohamae identifies novel antimicrobial peptide genes

The marbled flounder (Pseudopleuronectes yokohamae) is highly esteemed for its exceptional nutritional value and delicious taste. However, this species has extremely limited transcriptome data, which can offer priceless information for disease protection. In the study, the skin transcriptomic sequencing of P. yokohamae revealed 7.72 GB of clean data using the Nanopore sequencing platform. The results revealed 30,498 transcripts of functional annotations in the P. yokohamae transcriptome. All transcripts were searched in eight functional databases. A total of 10,337 ORFs were obtained, of which 6081 complete ORFs accounted for 58.83% of all predicted CDS. Moreover, 10,195 SSRs were detected. Meanwhile, the non-pecific immunity pathways were investigated for better understanding of the immunological reaction in P. yokohamae, and seven innate immune pathways were identified. The innate-immune related genes were highly expressed in the NOD-like receptor signaling pathway, followed by the C-type lectin receptor signaling pathway, Toll-like receptor signaling pathway, RIG-I-like receptor signaling pathway and Cytosolic DNA-sensing pathway. In this study, four families of antimicrobial peptides (AMPs) in P. yokohamae were analysed for the first time, including piscidins, hepcidins, liver-expressed antimicrobial peptide and defensins. Seven AMPs, including Pypleurocidin-like WF3, Pypleurocidin-like WFX, Pyhepcidin 1, Pyhepcidin-like 1, PyLEAP-2, Pybeta-defensin and Pybeta-defensin-like 1, were further identified. The seven AMPs showed a highly identity in their cDNA and genomic structures and an inducible expression pattern preferable to skin in response to pathogens. The transcriptomic data and investigation of AMPs from P. yokohamae promote a deeper awareness of fish mucosal immunity and provide information in the prevention of fish diseases.

Role of HIF-1α-Activated IL-22/IL-22R1/Bmi1 Signaling Modulates the Self-Renewal of Cardiac Stem Cells in Acute Myocardial Ischemia

Impaired tissue regeneration negatively impacts on left ventricular (LV) function and remodeling after acute myocardial infarction (AMI). Little is known about the intrinsic regulatory machinery of ischemia-induced endogenous cardiac stem cells (eCSCs) self-renewing divisions after AMI. The interleukin 22 (IL-22)/IL-22 receptor 1 (IL-22R1) pathway has emerged as an important regulator of several cellular processes, including the self-renewal and proliferation of stem cells. However, whether the hypoxic environment could trigger the self-renewal of eCSCs via IL-22/IL-22R1 activation remains unknown. In this study, the upregulation of IL-22R1 occurred due to activation of hypoxia-inducible factor-1α (HIF-1α) under hypoxic and ischemic conditions. Systemic IL-22 administration not only attenuated cardiac remodeling, inflammatory responses, but also promoted eCSC-mediated cardiac repair after AMI. Unbiased RNA microarray analysis showed that the downstream mediator Bmi1 regulated the activation of CSCs. Therefore, the HIF-1α-induced IL-22/IL-22R1/Bmi1 cascade can modulate the proliferation and activation of eCSCs in vitro and in vivo. Collectively, investigating the HIF-1α-activated IL-22/IL-22R1/Bmi1 signaling pathway might offer a new therapeutic strategy for AMI via eCSC-induced cardiac repair.

Absence of Langerhans cells resulted in over-influx of neutrophils and increased bacterial burden in skin wounds

Langerhans cells (LCs) are resident dendritic cells in the epidermis and their roles in presenting antigens derived from microorganisms present in the skin has been well appreciated. However, it is generally thought that incoming neutrophils are mainly responsible for eradicating invading pathogens in the early stage of wounds and a role of LCs in innate immunity is elusive. In the current study, we showed that wounds absent of LCs had a delayed closure. Mechanistically, LCs were the primary cells in warding off bacteria invasion at the early stage of wound healing. Without LCs, commensal bacteria quickly invaded and propagated in the wounded area. keratinocytes surrounding the wounds responded to the excessive bacteria by elevated production of CXCL5, resulting in an over-influx of neutrophils. The over-presence of activated neutrophils, possibly together with the aggravated invasion of bacteria, was detrimental to epidermal progenitor cell propagation and re-epithelialization. These observations underscore an indispensable role of LCs as effective guardians that preclude both bacteria invasion and damages inflicted by secondary inflammation.

The interaction of innate immune and adaptive immune system

The innate immune system serves as the body's first line of defense, utilizing pattern recognition receptors like Toll-like receptors to detect pathogens and initiate rapid response mechanisms. Following this initial response, adaptive immunity provides highly specific and sustained killing of pathogens via B cells, T cells, and antibodies. Traditionally, it has been assumed that innate immunity activates adaptive immunity; however, recent studies have revealed more complex interactions. This review provides a detailed dissection of the composition and function of the innate and adaptive immune systems, emphasizing their synergistic roles in physiological and pathological contexts, providing new insights into the link between these two forms of immunity. Precise regulation of both immune systems at the same time is more beneficial in the fight against immune-related diseases, for example, the cGAS-STING pathway has been found to play an important role in infections and cancers. In addition, this paper summarizes the challenges and future directions in the field of immunity, including the latest single-cell sequencing technologies, CAR-T cell therapy, and immune checkpoint inhibitors. By summarizing these developments, this review aims to enhance our understanding of the complexity interactions between innate and adaptive immunity and provides new perspectives in understanding the immune system.

Lung antimicrobial proteins and peptides: from host defense to therapeutic strategies

Representing severe morbidity and mortality globally, respiratory infections associated with chronic respiratory diseases, including complicated pneumonia, asthma, interstitial lung disease, and chronic obstructive pulmonary disease, are a major public health concern. Lung health and the prevention of pulmonary disease rely on the mechanisms of airway surface fluid secretion, mucociliary clearance, and adequate immune response to eradicate inhaled pathogens and particulate matter from the environment. The antimicrobial proteins and peptides contribute to maintaining an antimicrobial milieu in human lungs to eliminate pathogens and prevent them from causing pulmonary diseases. The predominant antimicrobial molecules of the lung environment include human α- and β-defensins and cathelicidins, among numerous other host defense molecules with antimicrobial and antibiofilm activity such as PLUNC (palate, lung, and nasal epithelium clone) family proteins, elafin, collectins, lactoferrin, lysozymes, mucins, secretory leukocyte proteinase inhibitor, surfactant proteins SP-A and SP-D, and RNases. It has been demonstrated that changes in antimicrobial molecule expression levels are associated with regulating inflammation, potentiating exacerbations, pathological changes, and modifications in chronic lung disease severity. Antimicrobial molecules also display roles in both anticancer and tumorigenic effects. Lung antimicrobial proteins and peptides are promising alternative therapeutics for treating and preventing multidrug-resistant bacterial infections and anticancer therapies.

Streptomyces Endophytes in Edible Plants: New Insights into their Chemistry and Health Benefits

Streptomyces is the largest source of microbial antibiotics with about 50 % of marketed antimicrobial drugs originating from this genus. Endophytic streptomyces are the link between medicinal plants and the microbial world. Endophytic Streptomyces in edible plants were not targeted before despite their uniqueness and importance. In this review, we analyzed the chemical diversity of more than 150 compounds belonging to endophytic Streptomyces chemical classes such as alkaloids, polyketides, peptides, macrolides and terpenes and their biological activities. This analysis showed a dominant antimicrobial effect for most of the isolated compounds and highlighted an underestimated diversity to be studied or repurposed for other biological activities. Return to edible plants use and conducting toxicity studies to rationalize their nutraceutical potential based on their beneficial endophytes is urged. Although there are many studies for non-vertebrates, the nutraceutical potential of these plants is expected to improve the gut microbiota since they are enriched with bioactive compounds from streptomyces species. This is the first review to discuss edible plants associated streptomyces, and we prospect that many studies will follow to unravel the mysterious health benefits of streptomyces in the human microbiome and encourage the revival of a correct lifestyle for the sake of a healthier microbiome.

Fusobacterium nucleatum extracellular vesicles are enriched in colorectal cancer and facilitate bacterial adhesion

Fusobacterium nucleatum in colorectal cancer (CRC) tissue is implicated at multiple stages of the disease, while the mechanisms underlying bacterial translocation and colonization remain incompletely understood. Herein, we investigated whether extracellular vesicles derived from F. nucleatum (FnEVs) have impacts on bacterial colonization. In mice with colitis-related CRC, a notable enrichment of FnEVs was observed, leading to a significant increase in intratumor colonization by F. nucleatum and accelerated progression of CRC. The enrichment of FnEVs in clinical CRC tissues was demonstrated. Subsequently, we revealed that FnEVs undergo membrane fusion with CRC cells, leading to the transfer and retention of FomA on recipient cell surfaces. Given its ability to facilitate F. nucleatum autoaggregation through interaction with FN1441, the presence of FomA on CRC cell surfaces presents a target for bacterial adhesion. Collectively, the findings unveil a mechanism used by EVs to prepare a niche conducive for bacterial colonization in distal organs.

Enterococcal-host interactions in the gastrointestinal tract and beyond

The gastrointestinal tract (GIT) is typically considered the natural niche of enterococci. However, these bacteria also inhabit extraintestinal tissues, where they can disrupt organ physiology and cause life-threatening infections. Here, we discuss how enterococci, primarily Enterococcus faecalis, interact with the intestine and other host anatomical locations such as the oral cavity, heart, liver, kidney, and vaginal tract. The metabolic flexibility of these bacteria allows them to quickly adapt to new environments, promoting their persistence in diverse tissues. In transitioning from commensals to pathogens, enterococci must overcome harsh conditions such as nutrient competition, exposure to antimicrobials, and immune pressure. Therefore, enterococci have evolved multiple mechanisms to adhere, colonize, persist, and endure these challenges in the host. This review provides a comprehensive overview of how enterococci interact with diverse host cells and tissues across multiple organ systems, highlighting the key molecular pathways that mediate enterococcal adaptation, persistence, and pathogenic behavior.

Protamine cleavage specificity of the avian pathogen Escherichia coli OmpT reveals two substrate-binding sites related to virulence

The pathogenic nature of bacteria can be increased by cleaving antimicrobial peptides using omptins, to avoid or counter the host's natural immune defenses. Plasmid-encoded OmpT (pOmpT or ArlC) in avian pathogenic Escherichia coli (APEC), like the chromosome-encoded OmpT (cOmpT), belongs to the omptin family and both exhibit highly similar sequences and structures. Through sequence alignment and physiological examinations, pOmpT has been identified as a virulence factor, distinct from cOmpT in terms of substrate specificity. When pOmpT is compared with cOmpT regarding their proteolytic activities and target substrates, Asp267 and Ser276 on loop 5 of cOmpT are found to be binding sites that facilitate substrate anchoring and enhance substrate cleavage (protamine or synthetic peptide) by the catalytic center. Conversely, the characteristics of residues at positions 267 and 276 on loop 5 of pOmpT inhibit protamine cleavage, yet allow the specific cleavage of the human antimicrobial peptide RNase 7, which plays a role in host defense. This finding suggests a relationship between these two binding sites and substrate specificity. Furthermore, the substrate-binding sites (residues 267 and 276, particularly residue 267) of cOmpT and pOmpT are determined to be critical in the virulence of APEC. In summary, residues 267 and 276 of pOmpT are crucial for the pathogenicity of APEC and offer new insights into the determinants of APEC virulence and the development of antimicrobial drugs.

Lauric acid reduces apoptosis by inhibiting FOXO3a-signaling in deoxynivalenol-treated IPEC-J2 cells

Deoxynivalenol (DON) is the most common mycotoxin contaminant of food or feed worldwide and causes disease in animals. Lauric acid (LA) is a medium-chain fatty acid useful for barrier functions such as antimicrobial activity in the intestine of monogastric animals. However, the molecular mechanisms by which lauric acid exerts its effects on the deoxynivalenol-exposed small intestine have not been studied. We used an intestinal porcine epithelial cell line (IPEC-J2) as an in vitro model to explore the molecular mechanism of lauric acid in alleviating deoxynivalenol-induced damage. We found that lauric acid reversed deoxynivalenol-induced reduction in cell viability. Our quantitative real-time polymerase chain reaction results indicated that lauric acid alleviated deoxynivalenol-induced apoptosis through Annexin-V. Additionally, immunofluorescence and Western blotting showed that lauric acid attenuated deoxynivalenol-induced forkhead box O3 (FOXO3a) translocation into the nucleus. These results suggest that lauric acid attenuates forkhead box O3 translocation in the small intestine damaged by deoxynivalenol, thereby reducing apoptosis. In conclusion, this study found that lauric acid alleviates deoxynivalenol-induced damage in intestinal porcine epithelial cell line through various molecular mechanisms.

Variation in the sensitivity of intestine and skin of Bufo gargarizans and Rana chensinensis tadpoles in relation to zinc exposure

Zinc (Zn) contaminants in the aquatic environment have an intricate impact on amphibians. Amphibian gut and skin microbiota are participated in regulating their normal physiological functions. Here, we investigated the effects of Zn on the gut and skin tissues and microbiota of Bufo gargarizans and Rana chensinensis tadpoles using histological methods and 16S rRNA sequencing technology. Our results showed a decrease in the height of enterocytes and skin epithelial cells after Zn treatment. Furthermore, Zn exposure elicited alterations in the composition and structure of the gut and skin microbiota at the phylum and genus levels in Bufo gargarizans and Rana chensinensis tadpoles. The feature predictions revealed an elevation in the abundance of potentially pathogenic bacteria and stress-tolerant bacteria in the gut and skin of both tadpoles after zinc exposure. We also speculated that microbiota from various species and organs exhibit varying degrees of sensitivity to zinc based on the functional predictions results. In the context of increasing environmental pollution and the global amphibians decline, our research enriches the current understanding of effects of zinc on amphibian microbiota and provides new framework for artificial breeding and amphibian conservation.

The gut microbiome: an important role in neurodegenerative diseases and their therapeutic advances

There are complex interactions between the gut and the brain. With increasing research on the relationship between gut microbiota and brain function, accumulated clinical and preclinical evidence suggests that gut microbiota is intimately involved in the pathogenesis of neurodegenerative diseases (NDs). Increasingly studies are beginning to focus on the association between gut microbiota and central nervous system (CNS) degenerative pathologies to find potential therapies for these refractory diseases. In this review, we summarize the changes in the gut microbiota in Alzheimer's disease, Parkinson's disease, multiple sclerosis, and amyotrophic lateral sclerosis and contribute to our understanding of the function of the gut microbiota in NDs and its possible involvement in the pathogenesis. We subsequently discuss therapeutic approaches targeting gut microbial abnormalities in these diseases, including antibiotics, diet, probiotics, and fecal microbiota transplantation (FMT). Furthermore, we summarize some completed and ongoing clinical trials of interventions with gut microbes for NDs, which may provide new ideas for studying NDs.

The skin microbiome stratifies patients with cutaneous T cell lymphoma and determines event-free survival

Mycosis fungoides (MF) is the most common entity of Cutaneous T cell lymphomas (CTCL) and is characterized by the presence of clonal malignant T cells in the skin. The role of the skin microbiome for MF development and progression are currently poorly understood. Using shotgun metagenomic profiling, real-time qPCR, and T cell receptor sequencing, we compared lesional and nonlesional skin of 20 MF patients with early and advanced MF. Additionally, we isolated Staphylococcus aureus and other bacteria from MF skin for functional profiling and to study the S. aureus virulence factor spa. We identified a subgroup of MF patients with substantial dysbiosis on MF lesions and concomitant outgrowth of S. aureus on plaque-staged lesions, while the other MF patients had a balanced microbiome on lesional skin. Dysbiosis and S. aureus outgrowth were accompanied by ectopic levels of cutaneous antimicrobial peptides (AMPs), including adaptation of the plaque-derived S. aureus strain. Furthermore, the plaque-derived S. aureus strain showed a reduced susceptibility towards antibiotics and an upregulation of the virulence factor spa, which may activate the NF-κB pathway. Remarkably, patients with dysbiosis on MF lesions had a restricted T cell receptor repertoire and significantly lower event-free survival. Our study highlights the potential for microbiome-modulating treatments targeting S. aureus to prevent MF progression.

Postbiotic lactobacilli induce cutaneous antimicrobial response and restore the barrier to inhibit the intracellular invasion of Staphylococcus aureus in vitro and ex vivo

Intracellular pathogens including Staphylococcus aureus contribute to the non-healing phenotype of chronic wounds. Lactobacilli, well known as beneficial bacteria, are also reported to modulate the immune system, yet their role in cutaneous immunity remains largely unknown. We explored the therapeutic potential of bacteria-free postbiotics, bioactive lysates of lactobacilli, to reduce intracellular S. aureus colonization and promote healing. Fourteen postbiotics derived from various lactobacilli species were screened, and Latilactobacillus curvatus BGMK2-41 was selected for further analysis based on the most efficient ability to reduce intracellular infection by S. aureus diabetic foot ulcer clinical isolate and S. aureus USA300. Treatment of both infected keratinocytes in vitro and infected human skin ex vivo with BGMK2-41 postbiotic cleared S. aureus. Keratinocytes treated in vitro with BGMK2-41 upregulated expression of antimicrobial response genes, of which DEFB4, ANG, and RNASE7 were also found upregulated in treated ex vivo human skin together with CAMP exclusively upregulated ex vivo. Furthermore, BGMK2-41 postbiotic treatment has a multifaceted impact on the wound healing process. Treatment of keratinocytes stimulated cell migration and the expression of tight junction proteins, while in ex vivo human skin BGMK2-41 increased expression of anti-inflammatory cytokine IL-10, promoted re-epithelialization, and restored the epidermal barrier via upregulation of tight junction proteins. Together, this provides a potential therapeutic approach for persistent intracellular S. aureus infections.

Interaction between Intestinal Parasites and the Gut Microbiota: Implications for the Intestinal Immune Response and Host Defence

Intestinal parasites, including helminths and protozoa, account for a significant portion of the global health burden. The gastrointestinal (GI) tract not only serves as the stage for these parasitic infections but also as the residence for millions of microbes. As the intricacies of the GI microbial milieu continue to unfold, it is becoming increasingly apparent that the interactions between host, parasite, and resident microbes help dictate parasite survival and, ultimately, disease outcomes. Across both clinical and experimental models, intestinal parasites have been shown to impact microbial composition and diversity. Reciprocally, microbes can directly influence parasitic survival, colonization and expulsion. The gut microbiota can also indirectly impact parasites through the influence and manipulation of the host. Studying this host-parasite-microbiota axis may help bring about novel therapeutic strategies for intestinal parasitic infection as well as conditions such as inflammatory bowel disease (IBD). In this review, we explore the relationship between intestinal parasites, with a particular focus on common protozoa and helminths, and the gut microbiota, and how these interactions can influence the host defence and intestinal immune response. We will also explore the impact of this tripartite relationship in a clinical setting and its broader implications for human health.

Bacterial extracellular vesicles: Vital contributors to physiology from bacteria to host

Bacterial extracellular vesicles (bEVs) represent spherical particles with diameters ranging from 20 to 400 nm filled with multiple parental bacteria-derived components, including proteins, nucleic acids, lipids, and other biomolecules. The production of bEVs facilitates bacteria interacting with their environment and exerting biological functions. It is increasingly evident that the bEVs play integral roles in both bacterial and host physiology, contributing to environmental adaptations to functioning as health promoters for their hosts. This review highlights the current state of knowledge on the composition, biogenesis, and diversity of bEVs and the mechanisms by which different bEVs elicit effects on bacterial physiology and host health. We posit that an in-depth exploration of the mechanistic aspects of bEVs activity is essential to elucidate their health-promoting effects on the host and may facilitate the translation of bEVs into applications as novel natural biological nanomaterials.

Gut-directed therapy in Parkinson's disease

Parkinson's disease (PD) is a common and slow-progressing neurodegenerative disorder characterized by motor and non-motor symptoms, including gastrointestinal (GI) dysfunctions. Over the last years, the microbiota-gut-brain (MGB) axis is emerging as a bacterial-neuro-immune ascending pathway that contributes to the progression of PD. Indeed, PD patients are characterized by changes in gut microbiota composition, alterations of intestinal epithelial barrier (IEB) and enteric neurogenic/inflammatory responses that, besides determining intestinal disturbances, contribute to brain pathology. In this context, despite the causal relationship between gut dysbiosis, impaired MGB axis and PD remains to be elucidated, emerging evidence shows that MGB axis modulation can represent a suitable therapeutical strategy for the treatment of PD. This review provides an overview of the available knowledge about the beneficial effects of gut-directed therapies, including dietary interventions, prebiotics, probiotics, synbiotics and fecal microbiota transplantation (FMT), in both PD patients and animal models. In this context, particular attention has been devoted to the mechanisms by which the modulation of MGB axis could halt or slow down PD pathology and, most importantly, how these approaches can be included in the clinical practice.

Single-cell view into the role of microbiota shaping host immunity in the larynx

Microbiota play a critical role in the development and training of host innate and adaptive immunity. We present the cellular landscape of the upper airway, specifically the larynx, by establishing a reference single-cell atlas, while dissecting the role of microbiota in cell development and function at single-cell resolution. We highlight the larynx's cellular heterogeneity with the identification of 16 cell types and 34 distinct subclusters. Our data demonstrate that commensal microbiota have extensive impact on the laryngeal immune system by regulating cell differentiation, increasing the expression of genes associated with host defense, and altering gene regulatory networks. We uncover macrophages, innate lymphoid cells, and multiple secretory epithelial cells, whose cell proportions and expressions vary with microbial exposure. These cell types play pivotal roles in maintaining laryngeal and upper airway health and provide specific guidance into understanding the mechanism of immune system regulation by microbiota in laryngeal health and disease.

Mechanisms of host adaptation by bacterial pathogens

The emergence of new infectious diseases poses a major threat to humans, animals, and broader ecosystems. Defining factors that govern the ability of pathogens to adapt to new host species is therefore a crucial research imperative. Pathogenic bacteria are of particular concern, given dwindling treatment options amid the continued expansion of antimicrobial resistance. In this review, we summarize recent advancements in the understanding of bacterial host species adaptation, with an emphasis on pathogens of humans and related mammals. We focus particularly on molecular mechanisms underlying key steps of bacterial host adaptation including colonization, nutrient acquisition, and immune evasion, as well as suggest key areas for future investigation. By developing a greater understanding of the mechanisms of host adaptation in pathogenic bacteria, we may uncover new strategies to target these microbes for the treatment and prevention of infectious diseases in humans, animals, and the broader environment.

Hundreds of antimicrobial peptides create a selective barrier for insect gut symbionts

The spatial organization of gut microbiota is crucial for the functioning of the gut ecosystem, although the mechanisms that organize gut bacterial communities in microhabitats are only partially understood. The gut of the insect Riptortus pedestris has a characteristic microbiota biogeography with a multispecies community in the anterior midgut and a monospecific bacterial population in the posterior midgut. We show that the posterior midgut region produces massively hundreds of specific antimicrobial peptides (AMPs), the Crypt-specific Cysteine-Rich peptides (CCRs) that have membrane-damaging antimicrobial activity against diverse bacteria but posterior midgut symbionts have elevated resistance. We determined by transposon-sequencing the genetic repertoire in the symbiont Caballeronia insecticola to manage CCR stress, identifying different independent pathways, including AMP-resistance pathways unrelated to known membrane homeostasis functions as well as cell envelope functions. Mutants in the corresponding genes have reduced capacity to colonize the posterior midgut, demonstrating that CCRs create a selective barrier and resistance is crucial in gut symbionts. Moreover, once established in the gut, the bacteria differentiate into a CCR-sensitive state, suggesting a second function of the CCR peptide arsenal in protecting the gut epithelia or mediating metabolic exchanges between the host and the gut symbionts. Our study highlights the evolution of an extreme diverse AMP family that likely contributes to establish and control the gut microbiota.

MUC21: a new target for tumor treatment

MUC21, also known as Epiglycanin, is a high-molecular-weight glycoprotein with transmembrane mucin properties. It consists of a tandem repeat domain, a stem domain, a transmembrane domain and a cytoplasmic tail. MUC21 is expressed is observed in normal tissues in organs like the thymus, testes, lungs, and large intestine. Research has shown that MUC21 is expressed in esophageal squamous cell carcinoma, lung adenocarcinoma, glioblastoma, thyroid cancer, melanoma, and various other malignant tumors in distinctive manner. Additionally, tumor invasion, metastasis, and poor prognosis are linked to it. Some researchers believe that MUC21 has the potential to become a new target in cancer treatment. This review aims to deliver a comprehensive overview of the glycosylation, function, and research progress of MUC21 in multiple types of cancer and infectious diseases.

Probiotic potential of Streptomyces levis strain HFM-2 isolated from human gut and its antibiofilm properties against pathogenic bacteria

BACKGROUND

Antimicrobial resistance (AMR) is a serious worldwide public health concern that needs immediate action. Probiotics could be a promising alternative for fighting antibiotic resistance, displaying beneficial effects to the host by combating diseases, improving growth, and stimulating the host immune responses against infection. This study was conducted to evaluate the probiotic, antibacterial, and antibiofilm potential of Streptomyces levis strain HFM-2 isolated from the healthy human gut.

RESULTS

In vitro antibacterial activity in the cell-free supernatant of S. levis strain HFM-2 was evaluated against different pathogens viz. K. pneumoniae sub sp. pneumoniae, S. aureus, B. subtilis, VRE, S. typhi, S. epidermidis, MRSA, V. cholerae, M. smegmatis, E. coli, P. aeruginosa and E. aerogenes. Further, the ethyl acetate extract from S. levis strain HFM-2 showed strong biofilm inhibition against S. typhi, K. pneumoniae sub sp. pneumoniae, P. aeruginosa and E. coli. Fluorescence microscopy was used to detect biofilm inhibition properties. MIC and MBC values of EtOAc extract were determined at 500 and 1000 µg/mL, respectively. Further, strain HFM-2 showed high tolerance in gastric juice, pancreatin, bile, and at low pH. It exhibited efficient adhesion properties, displaying auto-aggregation (97.0%), hydrophobicity (95.71%, 88.96%, and 81.15% for ethyl acetate, chloroform and xylene, respectively), and showed 89.75%, 86.53%, 83.06% and 76.13% co-aggregation with S. typhi, MRSA, S. pyogenes and E. coli, respectively after 60 min of incubation. The S. levis strain HFM-2 was susceptible to different antibiotics such as tetracycline, streptomycin, kanamycin, ciprofloxacin, erythromycin, linezolid, meropenem, amikacin, gentamycin, clindamycin, moxifloxacin and vancomycin, but resistant to ampicillin and penicillin G.

CONCLUSION

The study shows that S. levis strain HFM-2 has significant probiotic properties such as good viability in bile, gastric juice, pancreatin environment, and at low pH; proficient adhesion properties, and antibiotic susceptibility. Further, the EtOAc extract of Streptomyces levis strain HFM-2 has a potent antibiofilm and antibacterial activity against antibacterial-resistant clinical pathogens.

Mechanisms of medicinal, pharmaceutical, and immunomodulatory action of probiotics bacteria and their secondary metabolites against disease management: an overview

Probiotics or bacteriotherapy is today's hot issue for public entities (Food and Agriculture Organization, and World Health Organization) as well as health and food industries since Metchnikoff and his colleagues hypothesized the correlation between probiotic consumption and human's health. They contribute to the newest and highly efficient arena of promising biotherapeutics. These are usually attractive in biomedical applications such as gut-related diseases like irritable bowel disease, diarrhea, gastrointestinal disorders, fungal infections, various allergies, parasitic and bacterial infections, viral diseases, and intestinal inflammation, and are also worth immunomodulation. The useful impact of probiotics is not limited to gut-related diseases alone. Still, these have proven benefits in various acute and chronic infectious diseases, like cancer, human immunodeficiency virus (HIV) diseases, and high serum cholesterol. Recently, different researchers have paid special attention to investigating biomedical applications of probiotics, but consolidated data regarding bacteriotherapy with a detailed mechanistically applied approach is scarce and controversial. The present article reviews the bio-interface of probiotic strains, mainly (i) why the demand for probiotics?, (ii) the current status of probiotics, (iii) an alternative to antibiotics, (iv) the potential applications towards disease management, (v) probiotics and industrialization, and (vi) futuristic approach.

Vaccine targeting to mucosal lymphoid tissues promotes humoral immunity in the gastrointestinal tract

Viruses, bacteria, and parasites frequently cause infections in the gastrointestinal tract, but traditional vaccination strategies typically elicit little or no mucosal antibody responses. Here, we report a strategy to effectively concentrate immunogens and adjuvants in gut-draining lymph nodes (LNs) to induce gut-associated mucosal immunity. We prepared nanoemulsions (NEs) based on biodegradable oils commonly used as vaccine adjuvants, which encapsulated a potent Toll-like receptor agonist and displayed antigen conjugated to their surface. Following intraperitoneal administration, these NEs accumulated in gut-draining mesenteric LNs, priming strong germinal center responses and promoting B cell class switching to immunoglobulin A (IgA). Optimized NEs elicited 10- to 1000-fold higher antigen-specific IgG and IgA titers in the serum and feces, respectively, compared to free antigen mixed with NE, and strong neutralizing antibody titers against severe acute respiratory syndrome coronavirus 2. Thus, robust gut humoral immunity can be elicited by exploiting the unique lymphatic collection pathways of the gut with a lymph-targeting vaccine formulation.

Epithelial-neuronal-immune cell interactions: Implications for immunity, inflammation, and tissue homeostasis at mucosal sites

The epithelial lining of the respiratory tract and intestine provides a critical physical barrier to protect host tissues against environmental insults, including dietary antigens, allergens, chemicals, and microorganisms. In addition, specialized epithelial cells communicate directly with hematopoietic and neuronal cells. These epithelial-immune and epithelial-neuronal interactions control host immune responses and have important implications for inflammatory conditions associated with defects in the epithelial barrier, including asthma, allergy, and inflammatory bowel diseases. In this review, we discuss emerging research that identifies the mechanisms and impact of epithelial-immune and epithelial-neuronal cross talk in regulating immunity, inflammation, and tissue homeostasis at mucosal barrier surfaces. Understanding the regulation and impact of these pathways could provide new therapeutic targets for inflammatory diseases at mucosal sites.

Roles of airway and intestinal epithelia in responding to pathogens and maintaining tissue homeostasis

Epithelial cells form a resilient barrier and orchestrate defensive and reparative mechanisms to maintain tissue stability. This review focuses on gut and airway epithelia, which are positioned where the body interfaces with the outside world. We review the many signaling pathways and mechanisms by which epithelial cells at the interface respond to invading pathogens to mount an innate immune response and initiate adaptive immunity and communicate with other cells, including resident microbiota, to heal damaged tissue and maintain homeostasis. We compare and contrast how airway and gut epithelial cells detect pathogens, release antimicrobial effectors, collaborate with macrophages, Tregs and epithelial stem cells to mount an immune response and orchestrate tissue repair. We also describe advanced research models for studying epithelial communication and behaviors during inflammation, tissue injury and disease.