Induction Of Antimicrobial Peptides Research Articles

Assessment of peripheral blood toll-like receptor 2 expression and vitamin D serum level as predictors of response to intralesional vitamin D in the treatment of warts

Background Warts are common dermatological conditions caused by human papilloma virus. Most treatments for human papilloma virus rely on the destruction of involved tissue. The role of vitamin D injection in treating warts is thought to be via regulating cell proliferation and differentiation through the upregulation of vitamin D receptors and the induction of antimicrobial peptides. Objective To assess the clinical efficacy and safety of intralesional vitamin D in the treatment of cutaneous warts and also the significance of peripheral blood toll-like receptors 2 (TLR2) expression and serum levels of 25-hydroxyvitamin D in predicting the therapeutic success. Patients and methods In this prospective interventional study, 50 patients of cutaneous warts were subjected to history taking, proper dermatological examination, and peripheral venous blood collection for detection of TLR2 mRNA expression and a serum level of 25 (OH) D. Vitamin D3 was slowly injected into the base of the largest or the oldest wart at 2-week intervals. Results A total of 34 (69.4%) patients showed response to intralesional Vitamin D [21 (42.9%) showed complete resolution of all lesions, 13 (26.5%) showed partial clearing] and 15 (30.6%) patients showed poor or no response after four sessions. Serum level of vitamin D did not show a significant relation with treatment response. TLR2 expression was higher in the group showing complete response. Conclusion Intralesional vitamin D injection offers a safe and cost-effective therapy for different types of cutaneous warts. TLR2 expression in patients’ serum can be used to predict response to treatment by intralesional vitamin D, with better response in patients with higher expression.

Defensins of the stable fly (Stomoxys Calcitrans) have developmental-specific regulation and evolve at different rates.

Organisms produce antimicrobial peptides (AMPs) either in response to infection (induced) or continuously (constitutively) to combat microbes encountered during normal trophic activities and/or through pathogenic infections. The expression of AMPs is tightly regulated often with specificity to particular tissues or developmental stages. As a result, AMPs face varying selective pressures based on the microbes the organism's tissue or developmental stage encounters. Here, we analyzed the evolution and developmental-specific expression of Defensins, which are ancient AMPs in insects, in the stable fly (Stomoxys calcitrans). Stable fly larvae inhibit microbe-rich environments, whereas adult flies, as blood-feeders, experience comparatively fewer encounters with diverse microbial communities. Using existing RNA-seq datasets, we identified six Defensins that were only expressed in larvae (larval Defensins) and five that were not expressed in larvae (non-larval Defensins). Each of the non-larval Defensins was expressed in at least one adult tissue sample. Half of the larval Defensins were induced by mating or feeding in adults, and all three of the induced Defensins were located downstream of canonical binding sites for an Imd transcription factor involved in the highly conserved NF-κB signaling that regulates induction of AMPs. The larval and non-larval Defensins were located in distinct genomic regions, and the amino acid sequences of the larval Defensins formed a monophyletic clade. There were more amino acid substitutions across non-larval Defensins, with multiple genes losing a highly conserved furin cleavage site thought to be required for the removal of the amino terminus from the mature Defensin domain. However, larval Defensins had a higher proportion of radical amino acid substitutions, altering amino acid size and polarity. Our results reveal insights into the developmental stage-specific regulation of AMPs, and they suggest different regulatory regimes impose unique selection pressures on AMPs, possibly as a result of variation in exposure to microbial communities across development.

Understanding the Dynamics of Human Defensin Antimicrobial Peptides: Pathogen Resistance and Commensal Induction.

Antimicrobial peptides (AMPs), also known as host defense peptides, are petite molecules with inherent microbicidal properties that are synthesized by the host's innate immune response. These peptides serve as an initial barrier against pathogenic microorganisms, effectively eliminating them. Human defensin (HD) AMPs represent a prominent group of peptides involved in the innate immune response of humans. These peptides are primarily produced by neutrophils and epithelial cells, serving as a crucial defense mechanism against invading pathogens. The extensive research conducted has focused on the broad spectrum of antimicrobial activities and multifaceted immunomodulatory functions exhibited by human defensin AMPs. During the process of co-evolution between hosts and bacterial pathogens, bacteria have developed the ability to recognize and develop an adaptive response to AMPs to counterattack their bactericidal activity by different antibiotic-resistant mechanisms. However, numerous non-pathogenic commensal bacteria elicit the upregulation of defensins as a means to surmount the resistance mechanisms implemented by pathogens. The precise mechanism underlying the induction of HD by commensal organisms remains to be fully understood. This review summarizes the most recent research on the expression of human defensin by pathogens and discusses the various defense mechanisms used by pathogens to counter host AMP production. We also mention recent developments in the commensal induction of defensin AMPs. A better knowledge of the pathogens' defensin AMP resistance mechanisms and commensals' induction of AMP expression may shed light on the creation of fresh antibacterial tactics to get rid of bacterial infection.

Vitamin D supply, respiratory viral infections and persistent wheezing in children: how significant is the relationship?

The review discusses the multifaceted effect of vitamin D on antiviral immunity, induction of antimicrobial peptides, functional activity of immunocompetent cells, autophagy processes, clearance of viruses and viral fragments. The relationship between vitamin D and allergic inflammatory cells, its modulating and tolerogenic potential is considered. The inhibitory effect of vitamin D on eosinophils, mast cells, the production of pro-inflammatory and proallergic mediators, and the synthesis of IgE has been shown. The protective role of vitamin D in the development of remodeling and hyperresponsiveness of the respiratory tract has been established by reducing the number of goblet cells, mucus hypersecretion, and the expression of metalloproteinases. The effects of vitamin D on the replication of respiratory viruses and experimental resistance to them through the induction of antimicrobial peptides and other mechanisms have been demonstrated. Data from clinical studies on the preventive effect of vitamin D on the incidence of respiratory infections and episodes of persistent wheezing in children are presented. Children with respiratory syncytial infection and vitamin D deficiency were more likely to require respiratory support and mechanical ventilation. The preventive role of vitamin D in the development of obstructive bronchitis in children and severe bronchiolitis in infants has been shown. It has been established that normal levels of 25(OH)D in the mother significantly reduce the risk of developing bronchial obstruction in the child. Alternative data that do not support a protective effect of vitamin D on respiratory morbidity and wheezing in children are discussed. Further monitoring studies that take into account geographic location and analysis of the dose of cholecalciferol used to assess its preventive role in the development of wheezing and bronchial asthma in children are advisable.

Drosophila melanogaster Sting mediates Coxiella burnetii infection by reducing accumulation of reactive oxygen species.

The Gram-negative bacterium Coxiella burnetii is the causative agent of query fever in humans and coxiellosis in livestock. C. burnetii infects a variety of cell types, tissues, and animal species including mammals and arthropods, but there is much left to be understood about the molecular mechanisms at play during infection in distinct species. Human stimulator of interferon genes (STING) induces an innate immune response through the induction of type I interferons (IFNs), and IFN promotes or suppresses C. burnetii replication, depending on tissue type. Drosophila melanogaster contains a functional STING ortholog (Sting) which activates NF-κB signaling and autophagy. Here, we sought to address the role of D. melanogaster Sting during C. burnetii infection to uncover how Sting regulates C. burnetii infection in flies. We show that Sting-null flies exhibit higher mortality and reduced induction of antimicrobial peptides following C. burnetii infection compared to control flies. Additionally, Sting-null flies induce lower levels of oxidative stress genes during infection, but the provision of N-acetyl-cysteine (NAC) in food rescues Sting-null host survival. Lastly, we find that reactive oxygen species levels during C. burnetii infection are higher in Drosophila S2 cells knocked down for Sting compared to control cells. Our results show that at the host level, NAC provides protection against C. burnetii infection in the absence of Sting, thus establishing a role for Sting in protection against oxidative stress during C. burnetii infection.

Effects of TmTak1 silencing on AMP production as an Imd pathway component in Tenebrio molitor

Mealworms beetles, Tenebrio molitor, are the limelight next-generation food for humans due to their high nutrient contents. Since Tenebrio molitor is used as feed for pets and livestock in addition to their ability to decompose polystyrene and plastic waste, it is recognized as an insect with an industrial core value. Therefore, it is important to study the immune mechanism related to the development and infection of mealworms for mass breeding purposes. The immune deficiency (Imd) signaling is one of the main pathways with pivotal roles in the production of antimicrobial peptides (AMPs). Transforming growth factor-β activated kinase (TAK1) is one of the Imd pathway components, forms a complex with TAK1 binding protein 2 (TAB2) to ultimately help activate the transcription factor Relish and eventually induce host to produce AMPs. Relatively, little has been revealed about TAK1 in insect models, especially in the T. molitor. Therefore, this study was conducted to elucidate the function of TmTak1 in T. molitor. Our results showed that the highest and lowest mRNA expression of TmTak1 were found in egg and young larvae respectively. The tissue-specific expression patterns were reported in the gut of T. molitor larvae and the fat bodies of adults. Systemic microbial challenge illustrated TmTak1 high expression following the fungal infection in all dissected tissues except for the whole body. However, silencing TmTak1 experiments showed that the survivability of T. molitor larvae affected significantly following Escherichia coli infection. Accordingly, AMP induction after TmTak1 knock down was mainly reported in the integument and the fat bodies.

Intestinal epithelial pH-sensing receptor GPR65 maintains mucosal homeostasis via regulating antimicrobial defense and restrains gut inflammation in inflammatory bowel disease

ABSTRACT Intestinal epithelial cell (IEC) regulation of barrier function and mucosal homeostasis enables the establishment of a harmonious gut microenvironment. However, host-derived regulatory networks that modulate intestinal antimicrobial defenses have not been fully defined. Herein we generated mice with IEC-specific deletion of Gpr65 (Gpr65 ΔIEC) and investigated the role of epithelial GPR65 using DSS- and C. rodentium-induced murine colitis models. RNA sequencing analysis was conducted on colonic IECs from Gpr65 fl/fl and Gpr65 ΔIEC mice, and colonoids and colonic epithelial cell lines were used to evaluate the pH-sensing effect of GPR65. The expression of GPR65 was determined in IECs from patients with inflammatory bowel disease (IBD) and DSS colitis mice by qRT-PCR, Western blot, and immunohistochemistry, respectively. We observed that the absence of GPR65 in IECs abrogated homeostatic antimicrobial programs, including the production of antimicrobial peptides (AMPs) and defense response-associated proteins. Gpr65 ΔIEC mice displayed dysbiosis of the gut microbiota and were prone to DSS- and C. rodentium-induced colitis, as characterized by significantly disrupted epithelial antimicrobial responses, pathogen invasion, and increased inflammatory infiltrates in the inflamed colon. RNA sequencing analysis revealed that deletion of GPR65 in IECs provoked dramatic transcriptome changes with respect to the downregulation of immune and defense responses to bacteria. Forced AMP induction assays conducted in vivo or in ex vivo colonoids revealed that IEC-intrinsic GPR65 signaling drove antimicrobial defense. Mechanistically, GPR65 signaling promoted STAT3 phosphorylation to optimize mucosal defense responses. Epithelial cell line and colonoid assays further confirmed that epithelial GPR65 sensing pH synergized with IL-22 to facilitate antimicrobial responses. Finally, the expression of GPR65 was markedly decreased in the inflamed epithelia of IBD patients and DSS colitis mice. Our findings define an important role of epithelial GPR65 in regulating intestinal homeostasis and mucosal inflammation and point toward a potential therapeutic approach by targeting GPR65 in the treatment of IBD.

C. elegans Hemidesmosomes Sense Collagen Damage to Trigger Innate Immune Response in the Epidermis.

The collagens are an enormous family of extracellular matrix proteins that play dominant roles in cell adhesion, migration and tissue remodeling under many physiological and pathological conditions. However, their function mechanisms in regulating innate immunity remain largely undiscovered. Here we use C. elegans epidermis as the model to address this question. The C. elegans epidermis is covered with a collagen-rich cuticle exoskeleton and can produce antimicrobial peptides (AMPs) against invading pathogens or physical injury. Through an RNAi screen against collagen-encoding genes, we found that except the previously reported six DPY collagens and the BLI-1 collagen, the majority of collagens tested appear unable to trigger epidermal immune defense when damaged. Further investigation suggests that the six DPY collagens form a specific substructure, which regulates the interaction between BLI-1 and the hemidesmosome receptor MUP-4. The separation of BLI-1 with MUP-4 caused by collagen damage leads to the detachment of the STAT transcription factor-like protein STA-2 from hemidesmosomes and the induction of AMPs. Our findings uncover the mechanism how collagens are organized into a damage sensor and how the epidermis senses collagen damage to mount an immune defense.

Scavenger receptor B2, a type III membrane pattern recognition receptor, senses LPS and activates the IMD pathway in crustaceans

The immune deficiency (IMD) pathway is critical for elevating host immunity in both insects and crustaceans. The IMD pathway activation in insects is mediated by peptidoglycan recognition proteins, which do not exist in crustaceans, suggesting a previously unidentified mechanism involved in crustacean IMD pathway activation. In this study, we identified a Marsupenaeus japonicus B class type III scavenger receptor, SRB2, as a receptor for activation of the IMD pathway. SRB2 is up-regulated upon bacterial challenge, while its depletion exacerbates bacterial proliferation and shrimp mortality via abolishing the expression of antimicrobial peptides. The extracellular domain of SRB2 recognizes bacterial lipopolysaccharide (LPS), while its C-terminal intracellular region containing a cryptic RHIM-like motif interacts with IMD, and activates the pathway by promoting nuclear translocation of RELISH. Overexpressing shrimp SRB2 in Drosophila melanogaster S2 cells potentiates LPS-induced IMD pathway activation and diptericin expression. These results unveil a previously unrecognized SRB2-IMD axis responsible for antimicrobial peptide induction and restriction of bacterial infection in crustaceans and provide evidence of biological diversity of IMD signaling in animals. A better understanding of the innate immunity of crustaceans will permit the optimization of prevention and treatment strategies against the arising shrimp diseases.

The Endogenous Dual Retinoid Receptor Agonist Alitretinoin Exhibits Immunoregulatory Functions on Antigen-Presenting Cells.

Retinoids are a frequently used class of drugs in the treatment of inflammatory as well as malignant skin diseases. Retinoids have differential affinity for the retinoic acid receptor (RAR) and/or the retinoid X receptor (RXR). The endogenous dual RAR and RXR agonist alitretinoin (9-cis retinoic acid) demonstrated remarkable efficacy in the treatment of chronic hand eczema (CHE) patients; however, detailed information on the mechanisms of action remains elusive. Here, we used CHE as a model disease to unravel immunomodulatory pathways following retinoid receptor signaling. Transcriptome analyses of skin specimens from alitretinoin-responder CHE patients identified 231 significantly regulated genes. Bioinformatic analyses indicated keratinocytes as well as antigen presenting cells as cellular targets of alitretinoin. In keratinocytes, alitretinoin interfered with inflammation-associated barrier gene dysregulation as well as antimicrobial peptide induction while markedly inducing hyaluronan synthases without affecting hyaluronidase expression. In monocyte-derived dendritic cells, alitretinoin induced distinct morphological and phenotypic characteristics with low co-stimulatory molecule expression (CD80 and CD86), the increased secretion of IL-10 and the upregulation of the ecto-5'-nucleotidase CD73 mimicking immunomodulatory or tolerogenic dendritic cells. Indeed, alitretinoin-treated dendritic cells demonstrated a significantly reduced capacity to activate T cells in mixed leukocyte reactions. In a direct comparison, alitretinoin-mediated effects were significantly stronger than those observed for the RAR agonist acitretin. Moreover, longitudinal monitoring of alitretinoin-responder CHE patients could confirm in vitro findings. Taken together, we demonstrate that the dual RAR and RXR agonist alitretinoin targets epidermal dysregulation and demonstrates strong immunomodulatory effects on antigen presenting cell functions.

Indol-3-Carbinol ameliorates colitis in mice by AhR-mediated production of antimicrobial peptides and mucins

Abstract Indole-3-carbinol (I3C) is a dietary compound that acts as a ligand for the aryl hydrocarbon receptor (AhR), an important sensor for environmental polyaromatic chemicals and a regulator of the immune response. The pathogenesis of colitis involves multiple interactions between microbial dysbiosis, dysregulation of the host immune response, environmental factors, and host genetic profile. Indeed, studies have shown defective expression of AhR and antimicrobial peptides (AMPs) particularly defensins in inflammatory bowel disease (IBD) patients. Here, we investigated how I3C influences the production of AMPs, particularly b-defensins, through AhR and colonic microbiota composition in Anti-CD40 or dextran sulfate sodium (DSS)-induced colitis. Our analysis found that I3C attenuates colitis through AhR activation leading to increased expression of murine b-defensins (mBDs) by Colonic Epithelial Cells, resulting in the restoration of healthy gut microbiota and prevention of colonic inflammation. We analyzed the colonic expression of AMPs and mucins. Our analysis found that I3C significantly increased the mRNA expression of AhR, AMPs such as mBDs, Reg4, and mucins, when compared to vehicle-treated mice with colitis. Similarly, the mRNA levels of AhR, AMPs, and mucins were significantly increased in DSS+I3C-treated colon adenocarcinoma cells MC-38 (murine) and Caco2 (human) when compared to DSS-treated cells. To conclude, our findings demonstrate that I3C inhibits colitis primarily through AhR-mediated induction of AMPs and protective mucins, resulting in the enrichment of healthy gut microbiota (This work was supported in part by NIH grants R01ES030144, P01AT003961, P20GM103641, and R01AI123947, R01AI160896). This work was supported in part by NIH grants R01ES030144, P01AT003961, P20GM103641, and R01AI123947, R01AI160896

An Overview on the Function of Probiotics and Their Positive Effects on Enhancing Intestinal Immune Responses

Probiotics are alive and beneficial microorganisms that affect the body’s microbial flora when consumed by humans or animals and have beneficial effects on the health of the host. Nowadays, probiotics are considered a factor in the prevention of many infectious diseases and cancers. Given the particular importance of probiotics, this study aimed to narratively review previous studies on the mode of action of probiotics and the beneficial effects of probiotics on enhancing intestinal immune responses. Articles on this topic were searched in Google Scholar, Springer, Science Direct, and Clinical Trial databases, and systematic review articles examining the effects of probiotics on the function of the intestinal immune response were included in the study. The results of the research showed that probiotics can boost the body’s immune system, break down food due to their ability to produce enzymes, lower the pH of the environment, and secrete bacteriocins. Furthermore, the effect of probiotics on the modulation mechanisms of the innate defense responses of the intestinal epithelium, including the stimulation of trefoil factor 3, induction of antimicrobial peptide (AMP) secretion, stimulation of secretory immunoglobulin production, and stimulation of toll-like receptors increase in heat shock protein production, modulation of P-glycoprotein (P-gp) and regulation of mucins by probiotics. Therefore, probiotics are expected to be used as an adjunct treatment for many digestive and infectious diseases.

Protective Role of Vitamin D Against Development of Active Tuberculosis in Close Household Contacts of Pulmonary Tuberculosis Patients: A Prospective Cohort Study.

Vitamin-D is known to promote innate immune responses by acting as a cofactor of VDR for induction of antimicrobial peptides like cathelicidin. Close household contacts of pulmonary tuberculosis patients are at high risk of active infection, Therefore, possible role of vitamin-D in TB prevention through cathelicidin production was studied in high-risk household contacts (HHCs) of pulmonary tuberculosis (PTB) patients. 20 HHCs of PTB patients were recruited and followed up for one year. Levels of vitamin-D (25(OH)D) and its associated molecules were evaluated at 3-months intervals for one year or until the development of active TB. 25(OH)D was measured using chemiluminescence method. Serum VDR and cathelicidin levels were measured by ELISA and VDR mRNA expression by qPCR. Throughout the study period mean range of serum 25(OH)D levels was 20.51 ± 5.12 ng/ml. VDR and cathelicidin levels however showed significant decline after six months suggesting decrease in bacterial exposure. None of the HHCs developed active infection even with high exposure to 2 + to 3 + AFB positive index cases. Mantoux positive household contacts had high levels of VDR and cathelicidin, suggestive of an early or latent phase of infection, did not develop active TB plausibly due to maintenance of adequate serum levels of vitamin-D. Optimal levels of 25(OH)D and its associated molecules during early stages of infection may serve as protective factor against development of active TB. Cohort of HHCs with severely deficient vitamin-D levels (10 ng/ml) could be followed up for a better risk assessment.

Multiple mosquito AMPs are needed to potentiate their antifungal effect against entomopathogenic fungi.

Mosquito resistance to microbial infections, including fungal entomopathogens that are selected for mosquito control, depend on a range of antimicrobial effectors, among them antimicrobial peptides (AMPs). These short peptides, along the antimicrobial effector lysozyme, act by disrupting the microbial cell membrane or by interfering with microbial physiological processes. While the induction of AMPs and lysozyme during fungal entomopathogenic infections have been reported, their contribution to the mosquito antifungal response has not been evaluated. In this study, we assessed the induction of Ae. aegypti AMPs and lysozyme genes at two points of infection and against distinct entomopathogenic fungi. Our results indicate that fungal infection elicits the expression of cecropin, defensin, diptericin, holotricin, and lysozyme, but do not affect those of attacin or gambicin. We further evaluated the role of these antimicrobial effectors via RNAi-based depletion of select AMPs during challenges with two entomopathogenic fungi. Our results reveal that AMPs and lysozyme are critical to the antifungal response, acting in concert, rather than individually, to potentiate their antimicrobial effect against entomopathogenic fungi. This study further contributes to a better understanding of the mechanisms that confer resistance to entomopathogenic fungi in an important mosquito vector.

A Drosophila ortholog of Toll‐like receptors modulates c‐Jun N‐terminal kinase signaling and protects against tau‐mediated neurodegeneration independent of innate immune response

AbstractBackgroundInnate immunity is dysregulated in aging and neurodegenerative diseases, and Toll‐like receptors (TLRs) play a central role in innate immune response. Nine Toll family receptors (Toll‐1 to Toll‐9) exist in Drosophila, and Toll‐9 is structurally most closely related to mammalian TLRs such as TLR1, 2, 6, 10. However, physiological roles of Toll‐9 in innate immunity and neurodegeneration are largely unknown. In this study, we examined roles of Toll‐9 in fly brains under neurodegenerative conditions.MethodWe systematically investigated potential roles of Toll‐9 in the maintenance of the brain integrity under neurodegenerative conditions, using Drosophila models of acute axon injury and human tau‐mediated neurodegeneration.ResultExpression level of Toll‐9 was very low in brains under normal condition but was dramatically increased upon acute nerve injury, suggesting a potential role of Toll‐9 in neurodegeneration. Innate immune response including induction of antimicrobial peptides and glial phagocytic activity of degenerating neurons were activated by nerve injury in fly brains, though Toll‐9 knockout did not affect these responses. Interestingly, however, Toll‐9 knockout significantly impaired activation of stress signaling cascades including c‐Jun N‐terminal kinase pathway. To ask whether Toll‐9 modify severity of neurodegeneration, we employed a fly model of tauopathy and found that Toll‐9 knockdown significantly exacerbated axon degeneration accompanied by pathological tau phosphorylation.ConclusionThese results demonstrate that Drosophila Toll‐9 confers neuroprotective effects through activation of stress kinase signaling independent of induction of innate immune genes, which may provide insights into the pathogenesis of neurodegenerative diseases.

Drosophila hemocytes recognize lymph gland tumors of mxc mutants and activate the innate immune pathway in a reactive oxygen species-dependent manner.

Mechanisms of cancer cell recognition and elimination by the innate immune system remains unclear. The immune signaling pathways are activated in the fat body to suppress the tumor growth in mxcmbn1 hematopoietic tumor mutants in Drosophila by inducing antimicrobial peptides (AMP). Here, we investigated the regulatory mechanism underlying the activation in the mutant. Firstly, we found that reactive oxygen species (ROS) accumulated in the hemocytes due to induction of dual oxidase and one of its activators. This was required for the AMP induction and the tumor growth suppression. Next, more hemocytes transplanted from normal larvae were associated with the mutant tumor than normal lymph glands (LGs). Matrix metalloproteinase 1 and 2 (MMP2) were highly expressed in the tumors. The basement membrane components in the tumors were reduced and ultimately lost inside. Depletion of the MMP2 rather than MMP1 resulted in a significantly reduced AMP expression in the mutant larvae. The hemocytes may recognize the disassembly of basement membrane in the tumors and activate the ROS production. Our findings highlight the mechanism via which macrophage-like hemocytes recognize tumor cells and subsequently convey the information to induce AMPs in the fat body. They contribute to uncover the role of innate immune system against cancer.

Vitamin D enhances type I IFN signaling in COVID-19 patients

The ability of Vitamin D (VitD) to modulate antiviral responses through induction of antimicrobial peptide is well established. However, the effect of VitD on host responses to SARS-CoV-2 is not well investigated. We here report the ability of VitD to enhance host IFN-alpha/beta (a/β) signaling both in vitro and among severe COVID-19 patients treated with VitD. Blood and saliva specimens were obtained from severe COVID-19 patients treated (43 patients), or not (37 patients), with vitD, during their stay in intensive care unit. Patients were followed up to 29 days following admission, and patient survival outcomes were collected. Higher activity levels of RIG-1/MDA-5 and JAK-STAT signaling pathways were observed with significantly higher gene and protein levels of antiviral interferon stimulating genes (ISGs) such as MX-1 and ISG-15; both in vitro, following treatment of PBMCs with vitD, and in whole blood and saliva specimens of VitD treated patients. Moreover, VitD treated patients had lower risk of all-cause mortality by day 29 compared to untreated patients (adjusted hazard ratio, 0.37, 95% confidence interval of 0.14–0.94; P = 0.038). The herein uncovered regulatory role of VitD on type I IFNs suggests the importance of insuring a normal level of VitD for the prevention and probably treatment of SARS-CoV-2 infection. Additional mechanistic studies, however, are needed to fully elucidate the antiviral effects of VitD particularly in the setting of COVID-19 infection.

Efficient compartmentalization in insect bacteriomes protects symbiotic bacteria from host immune system.

BackgroundMany insects house symbiotic intracellular bacteria (endosymbionts) that provide them with essential nutrients, thus promoting the usage of nutrient-poor habitats. Endosymbiont seclusion within host specialized cells, called bacteriocytes, often organized in a dedicated organ, the bacteriome, is crucial in protecting them from host immune defenses while avoiding chronic host immune activation. Previous evidence obtained in the cereal weevil Sitophilus oryzae has shown that bacteriome immunity is activated against invading pathogens, suggesting endosymbionts might be targeted and impacted by immune effectors during an immune challenge. To pinpoint any molecular determinants associated with such challenges, we conducted a dual transcriptomic analysis of S. oryzae’s bacteriome subjected to immunogenic peptidoglycan fragments.ResultsWe show that upon immune challenge, the bacteriome actively participates in the innate immune response via induction of antimicrobial peptides (AMPs). Surprisingly, endosymbionts do not undergo any transcriptomic changes, indicating that this potential threat goes unnoticed. Immunohistochemistry showed that TCT-induced AMPs are located outside the bacteriome, excluding direct contact with the endosymbionts.ConclusionsThis work demonstrates that endosymbiont protection during an immune challenge is mainly achieved by efficient confinement within bacteriomes, which provides physical separation between host systemic response and endosymbionts. Video Supplementary InformationThe online version contains supplementary material available at 10.1186/s40168-022-01334-8.

525 How the inappropriate innate immune response of atopic dermatitis promotes dysbiosis of the skin microbiome

A hallmark of atopic dermatitis (AD) is colonization by S. aureus (SA) due to insufficient induction of antimicrobial peptides (AMPs) by Th2-skewing and loss of strains of coagulase-negative Staphylococcus (CoNS) that produce antimicrobials (AMs). These CoNS-AM+ strains normally outcompete SA from the skin microbiome. To understand the mechanism responsible for dysbiosis of the microbiome in AD, 5 strains of CoNS-AM+ and 5 strains of CoNS-AM-(without AMs), representing both S. hominis and S. epidermidis, were applied to skin of control mice or mice with AD-like Th2 inflammation induced by MC903. Survival of CoNS-AM+ strains on inflamed skin was 95% less than on controls after 48hr but CoNS-AM- strains survived equally well on non-inflamed and inflamed skin (P<0.01). In contrast, cathelicidin knockout mice (Camp-/-) treated with MC903 showed no loss of CoNS-AM+, suggesting this host AMP selectively eliminated CoNS-AM+ compared to CoNS-AM- strains. Conversely, genetic deletion of lantibiotics (a class of AM) from a CoNS-AM+ strain of S. hominis (ShA9) enabled its survival on inflamed skin of Camp+/+ mice and resulted in > 8-fold increased resistance to LL37 in vitro. When a mix of strains 33% SA : 37% ShA9 WT (AM+) : 30% ShA9DLanti (AM-) were applied to inflamed skin the bacterial CFU shifted over 72 hrs to enable expansion of SA and loss of CoNS-AM+ (74:5:21%). In contrast, SA was eliminated and CoNS-AM+ strains survived better on normal skin (8:46:46%). Similarly, when mixed strains were incubated in vitro with a low amount of LL37 (2μM), the proportion also shifted to an AD-like microbiome (53:5:42%). These results show that the combined activity from bacterial lantibiotics and host AMPs becomes auto-destructive to CoNS-AM+ strains on inflamed skin. We propose that low production of AMPs due to suppression by Th2-skewed conditions of AD is insufficient to inhibit SA but still selectively eliminates beneficial CoNS-AM+, thus promoting dysbiosis.

Codelivery of 1α,25-Dihydroxyvitamin D3 and CYP24A1 Inhibitor VID400 by Nanofiber Dressings Promotes Endogenous Antimicrobial Peptide LL-37 Induction.

Surgical site infections represent a significant clinical problem. Herein, we report a nanofiber dressing for topical codelivery of immunomodulating compounds including 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) and VID400, a CYP24A1 inhibitor in a sustained manner, for inducing the expression of the endogenous cathelicidin antimicrobial peptide (CAMP) gene encoding the hCAP18 protein, which is processed into the LL-37 peptide. Nanofiber wound dressings with coencapsulation of 1,25(OH)2D3 and VID400 were generated by electrospinning. Both 1,25(OH)2D3 and VID400 were coencapsulated into nanofibers with loading efficiencies higher than 90% and exhibited a prolonged release from nanofiber membranes longer than 28 days. Incubation with 1,25(OH)2D3/VID400-coencapsulated poly(ϵ-caprolactone) nanofiber membranes greatly induced the hCAP18/LL-37 gene expression in monocytes, neutrophils, and keratinocytes in vitro. Moreover, the administration of 1,25(OH)2D3/VID400-coencapsulated nanofiber membranes dramatically promoted the hCAP18/LL-37 expression in dermal wounds created in both human CAMP transgenic mice and human skin tissues. The 1,25(OH)2D3- and VID400-coencapsulated nanofiber dressings enhanced innate immunity via the more effective induction of antimicrobial peptide than the free drug alone or 1,25(OH)2D3-loaded nanofibers. Together, 1,25(OH)2D3/VID400-embedded nanofiber dressings presented in this study show potential in preventing surgical site infections.