Is the skin microbiota a modifiable risk factor for breast disease?: A systematic review

Purpose: High prevalence, unreliable risk discrimination and poor clinical outcomes are observed in malignant and benign breast diseases (BD). The involvement of microbial communities in the development of BD has become topical, and distal influences of microbial dysregulation in the breast have been well established. Despite advances, the role of the breast skin microbiota in BD remains unclear. Interactions between the skin microbiota and the underlying mucosal immune system are complex. In homeostasis, the skin offers a physical barrier protecting underlying breast tissue from skin commensals and noxious environmental triggers. Our review aims to illuminate the role of the skin microbiota in the development of BD. Methods: Adhering to the PRISMA protocol, a systematic review was conducted utilising the Medline and Embase search engines. Results: Through a comprehensive search of the last ten years, twenty-two studies satisfied the inclusion criteria. Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes were identified as the most prevalent phyla of both breast tissue and skin in healthy controls and BD. High abundance of skin commensals, specifically some species of Staphylococcus, have been linked in breast cancer and metastases. Similarly, dysregulated microbial abundance is also seen in inflammatory and implant-associated BD. These findings raise the hypothesis that the skin microbiota plays a role in tissue homeostasis and may contribute to a range of breast pathologies. Several mechanisms of microbial transfer to underlying tissue have been proposed, including retrograde transfer through ductal systems, breakdown of the skin barrier, and migration through nipple-aspirate fluid. Conclusion: Our review provides preliminary insights into the skin microbiota as a modifiable risk factor for BD. This raises opportunities for future studies in antimicrobials/probiotics as an adjunct to, or replacement of surgery; a diagnostic and/or prognostic tool for BD; and the possibility of conditioning the microbiota to manage BD

An open-label pilot single-subject study to monitor the impact of a Food-Based enteral formula on faecal short-chain fatty acid concentrations in children admitted to intensive care with sepsis

Background: Non-digestible dietary fiber undergoes fermentation by the intestinal microbiota to produce short-chain fatty acids (SCFAs). Intestinal SCFAs control the production of T-helper cells, antibodies and are involved in maintaining homeostasis of the mucosal system. Sepsis is the leading cause of mortality in hospitalised children and is treated with antibiotics which disrupts the normal maturation of the microbiome causing dysbiosis. This study assessed the impact of a high-fibre Food-Based formula on feed tolerance and faecal SCFA concentrations in children admitted to intensive care with sepsis. Methods: An open-label single-subject study was based on repeated observations over 14 days in children admitted to intensive care with sepsis who commenced a high-fiber Food-Based enteral formula Compleat®Paediatric, (Nestle Health Science). Stool samples were collected to measure SCFA concentrations (acetate, butyrate and propionate). A Wilcoxon Signed-Rank test was used to measure change in SCFA concentrations. Other data collection included feed tolerance, anthropometrics, antibiotic administration and inflammatory markers. Results: Twenty children with sepsis were recruited over six months. The mean age was 10.8 years (±5.6 years SD). The most common sepsis-related organ failure was the respiratory tract (50 %). The mean duration of mechanical ventilation was 9 days (±4 SD), 25 % of children were treated with more than two antibiotics during their time in intensive care. Faecal propionate and butyrate concentrations were maintained during the children's time in intensive care. Stool frequency reduced from 2.6 per day (±1.08 SD) at baseline to 1.2 per day (±0.45 SD) after one week in intensive care (p < 0.004). Conclusion: In this pilot study children admitted to intensive care with sepsis tolerated a Food-Based formula. Faecal butyrate and propionate concentrations were maintained whilst feeding on a high fiber Food-Based formula. Further research is warranted to assess whether a Food-Based formula is superior to a standard enteral formula in preserving the intestinal microbiota, thereby mitigating gastrointestinal complications associated with antibiotic-related dysbiosis

A critical role for ATF2 transcription factor in the regulation of E-selectin expression in response to non-endotoxin components of Neisseria meningitidis

Vascular injury is a serious complication of sepsis due to the gram-negative bacterium Neisseria meningitidis. One of the critical early steps in initiating this injury is via the interaction of leucocytes, particularly neutrophils, with adhesion molecules expressed on inflamed endothelium. We have previously demonstrated that both lipopolysaccharide (LPS) and non-LPS components of meningococci can induce very high levels of expression of the vascular endothelial cell adhesion molecule E-selectin, which is critical for early tethering and capture of neutrophils onto endothelium under flow. Using an LPS-deficient strain of meningococcus, we showed that very high levels of expression can be induced in primary endothelial cells, even in the context of weak activation of the major host signal transduction factor [nuclear factor-κB (NF-κB)]. In this study, we show that the particular propensity for N. meningitidis to induce high levels of expression is regulated at a transcriptional level, and demonstrate a significant role for phosphorylation of the ATF2 transcription factor, likely via mitogen-activated protein (MAP) kinases, on the activity of the E-selectin promoter. Furthermore, inhibition of E-selectin expression in response to the lpxA- strain by a p38 inhibitor indicates a significant role of a p38-dependent MAPK signalling pathway in ATF2 activation. Collectively, these data highlight the role that LPS and other bacterial components have in modulating endothelial function and their involvement in the pathogenesis of meningococcal sepsis. Better understanding of these multiple mechanisms induced by complex stimuli such as bacteria, and the specific inflammatory pathways they activate, may lead to improved, focused interventions in both meningococcal and potentially bacterial sepsis more generally

Neutrophil extracellular traps formation and clearance is enhanced in fever and attenuated in hypothermia

Fever and hypothermia represent two opposite strategies for fighting systemic inflammation. Fever results in immune activation; hypothermia is associated with energy conservation. Systemic Inflammatory Response Syndrome (SIRS) remains a significant cause of mortality worldwide. SIRS can lead to a broad spectrum of clinical symptoms but importantly, patients can develop fever or hypothermia. During infection, polymorphonuclear cells (PMNs) such as neutrophils prevent pathogen dissemination through the formation of neutrophil extracellular traps (NETs) that ensnare and kill bacteria. However, when dysregulated, NETs also promote host tissue damage. Herein, we tested the hypothesis that temperature modulates NETs homeostasis in response to infection and inflammation. NETs formation was studied in response to infectious (Escherichia coli, Staphylococcus aureus) and sterile (mitochondria) agents. When compared to body temperature (37°C), NETs formation increased at 40°C; interestingly, the response was stunted at 35°C and 42°C. While CD16+ CD49d+ PMNs represent a small proportion of the neutrophil population, they formed ~45-85% of NETs irrespective of temperature. Temperature increased formyl peptide receptor 1 (FPR1) expression to a differential extent in CD16+ CD49d- vs. CD49d+ PMNSs, suggesting further complexity to neutrophil function in hypo/hyperthermic conditions. The capacity of NETs to induce Toll-like receptor 9 (TLR9)-mediated NF-κB activation was found to be temperature independent. Interestingly, NET degradation was enhanced at higher temperatures, which corresponded with greater plasma DNase activity in response to temperature increase. Collectively, our observations indicate that NETs formation and clearance are enhanced at 40°C whilst temperatures of 35°C and 42°C attenuate this response. Targeting PMN-driven immunity may represent new venues for intervention in pathological inflammation

Delineation of the Innate and Adaptive T-Cell Immune Outcome in the Human Host in Response to Campylobacter jejuni Infection

Background: Campylobacter jejuni is the most prevalent cause of bacterial gastroenteritis worldwide. Despite the significant health burden this infection presents, molecular understanding of C. jejuni-mediated disease pathogenesis remains poorly defined. Here, we report the characterisation of the early, innate immune response to C. jejuni using an ex-vivo human gut model of infection. Secondly, impact of bacterial-driven dendritic cell activation on T-cell mediated immunity was also sought.Methodology: Healthy, control paediatric terminal ileum or colonic biopsy tissue was infected with C. jejuni for 8-12 hours. Bacterial colonisation was followed by confocal microscopy and mucosal innate immune responses measured by ELISA. Marked induction of IFN gamma with modest increase in IL-22 and IL-17A was noted. Increased mucosal IL-12, IL-23, IL-1 beta and IL-6 were indicative of a cytokine milieu that may modulate subsequent T-cell mediated immunity. C. jejuni-driven human monocyte-derived dendritic cell activation was followed by analyses of T cell immune responses utilising flow cytometry and ELISA. Significant increase in Th-17, Th-1 and Th-17/Th-1 double-positive cells and corresponding cytokines was observed. The ability of IFN gamma, IL-22 and IL-17 cytokines to exert host defence via modulation of C. jejuni adhesion and invasion to intestinal epithelia was measured by standard gentamicin protection assay.Conclusions: Both innate and adaptive T cell-immunity to C. jejuni infection led to the release of IFN gamma, IL-22 and IL-17A; suggesting a critical role for this cytokine triad in establishing host anti-microbial immunity during the acute and effectors phase of infection. In addition, to their known anti-microbial functions; IL-17A and IL-17F reduced the number of intracellular C. jejuni in intestinal epithelia, highlighting a novel aspect of how IL-17 family members may contribute to protective immunity against C. jejuni

Brief Report: Innate lymphoid cells and T-cells contribute to the IL-17A signature detected in the synovial fluid of patients with Juvenile Idiopathic Arthritis

OBJECTIVE: Evidence suggests that aberrant function of innate lymphoid cells (ILC), whose functional and transcriptional profile overlap with T helper (Th) cell subsets, contribute to immune-mediated pathologies. To date, analysis of Juvenile Idiopathic Arthritis (JIA) immune-pathology has concentrated on the contribution of CD4+ T-cells; we have previously identified an expansion of Th17 cells within the synovial fluid (SF) of JIA patients. Here, we extend this analysis to investigate a role for ILC and other IL-17 producing T-cell subsets. METHODS: ILC and CD3+ T-cell subsets were defined in peripheral blood mononuclear cells (PBMC) (healthy adult, healthy child and JIA patients) and JIA SF mononuclear cells (SFMC) using flow cytometry. Defined subsets in SFMC were correlated with clinical measures including physician's visual analogue scale (VAS), active joint count and erythrocyte sedimentation rate (ESR). Transcription factor and cytokine profiles of sorted ILC were assessed by qPCR. RESULTS: Group 1 ILC (ILC1), NKp44-group 3 ILC (NCR-ILC3) and NKp44+group 3 ILC (NCR+ILC3) were enriched in the JIA-SFMC compared to PBMC, which corresponded with an increase in transcripts for TBX21, IFNG and IL17A. Of the ILC subsets, NCR-ILC3 frequency in JIA-SFMC displayed the strongest positive association with clinical measures which was mirrored by an expansion in IL-17A+CD4+, IL-17A+CD8+ and IL-17A+γδ T-cells. CONCLUSION: We demonstrate that the strength of the IL-17A signature in JIA-SFMC is determined by multiple lymphoid cell-types, including NCR-ILC3, IL-17A+CD4+, IL-17A+CD8+ and IL-17A+γδ T-cells. These observations may have important implications for the development of stratified therapeutics. This article is protected by copyright. All rights reserved

Cervical gene delivery of the antimicrobial peptide, Human β‐defensin (HBD)-3, in a mouse model of ascending infection-related preterm birth

Approximately 40% of preterm births are preceded by microbial invasion of the intrauterine space; ascent from the vagina being the most common pathway. Within the cervical canal, antimicrobial peptides and proteins (AMPs) are important components of the cervical barrier which help to prevent ascending vaginal infection. We investigated whether expression of the AMP, human β-defensin-3 (HBD3), in the cervical mucosa of pregnant mice could prevent bacterial ascent from the vagina into the uterine cavity. An adeno-associated virus vector containing both the HBD3 gene and GFP transgene (AAV8 HBD3.GFP) or control AAV8 GFP, was administered intravaginally into E13.5 pregnant mice. Ascending infection was induced at E16.5 using bioluminescent Escherichia coli (E. coli K1 A192PP-lux2). Bioluminescence imaging showed bacterial ascent into the uterine cavity, inflammatory events that led to premature delivery and a reduction in pups born alive, compared with uninfected controls. Interestingly, a significant reduction in uterine bioluminescence in the AAV8 HBD3.GFP-treated mice was observed 24 h post-E. coli infection, compared to AAV8 GFP treated mice, signifying reduced bacterial ascent in AAV8 HBD3.GFP-treated mice. Furthermore, there was a significant increase in the number of living pups in AAV HBD3.GFP-treated mice. We propose that HBD3 may be a potential candidate for augmenting cervical innate immunity to prevent ascending infection-related preterm birth and its associated neonatal consequences