Crosstalk between gut microbiota and sepsis

recAP administration ameliorates sepsis outcomes through modulation of gut and liver inflammation

Sepsis, broadly described as a systemic infection, is one of the leading causes of death and long-term disability worldwide. There are limited therapeutic options available that either improve survival and/or improve the quality of life in survivors. Ilofotase alfa, also known as recombinant alkaline phosphatase (recAP), has been associated with reduced mortality in a subset of patients with sepsis-associated acute kidney injury. However, whether recAP exhibits any therapeutic benefits in other organ systems beyond the kidney is less clear. The objective of this study was to evaluate the effects of recAP on survival, behavior, and intestinal inflammation in a mouse model of sepsis, cecal ligation and puncture (CLP). Following CLP, either recAP or saline vehicle was administered via daily intraperitoneal injections to determine its treatment efficacy from early through late sepsis. We found that administration of recAP suppressed indices of inflammation in the gut and liver but did not improve survival or behavioral outcomes. These results demonstrate that recAP's therapeutic efficacy in the gut and liver may provide a valuable treatment to improve long-term outcomes in sepsis survivors.

From Molecular Mechanisms to Clinical Therapy: Understanding Sepsis-Induced Multiple Organ Dysfunction

Sepsis-induced multiple organ dysfunction arises from the highly complex pathophysiology encompassing the interplay of inflammation, oxidative stress, endothelial dysfunction, mitochondrial damage, cellular energy failure, and dysbiosis. Over the past decades, numerous studies have been dedicated to elucidating the underlying molecular mechanisms of sepsis in order to develop effective treatments. Current research underscores liver and cardiac dysfunction, along with acute lung and kidney injuries, as predominant causes of mortality in sepsis patients. This understanding of sepsis-induced organ failure unveils potential therapeutic targets for sepsis treatment. Various novel therapeutics, including melatonin, metformin, palmitoylethanolamide (PEA), certain herbal extracts, and gut microbiota modulators, have demonstrated efficacy in different sepsis models. In recent years, the research focus has shifted from anti-inflammatory and antioxidative agents to exploring the modulation of energy metabolism and gut microbiota in sepsis. These approaches have shown a significant impact in preventing multiple organ damage and mortality in various animal sepsis models but require further clinical investigation. The accumulation of this knowledge enriches our understanding of sepsis and is anticipated to facilitate the development of effective therapeutic strategies in the future.

Genetic causal association between gut microbiota and sepsis: Evidence from a two-sample bidirectional Mendelian randomization analysis

Background

Sepsis is a severe and potentially life-threatening condition characterized by a dysregulated host response and organ dysfunction. The causal relationship between intestinal microbiota and sepsis is unclear.

Methods

A two-sample Mendelian randomization (MR) study was performed to proxy the causal association between gut microbiota and sepsis. The genome-wide association study (GWAS) data of sepsis and gut microbiome were collected from the Integrative Epidemiology Unit (IEU) OpenGWAS, with summary-level data obtained from the UK Biobank. Five traditional methods were used to estimate the potential causal relationships between gut microbiota and sepsis, including the inverse-variance weighted method, weighted median method, MR-Egger regression, simple mode, and weighted mode. Reverse MR analysis was performed on the bacteria that were found to be causally associated with sepsis in forward MR analysis. Cochran's Q statistic was used to quantify the heterogeneity of instrumental variables.

Results

The inverse-variance weighted estimate suggested that class Lentisphaeria (odds ratio [OR]=0.86, 95% confidence interval [CI]: 0.78 to 0.94, P=0.0017, q=0.1596) and order Victivallales (OR=0.86, 95% CI: 0.78 to 0.94, P=0.0017, q=0.1596) have a protective effect on sepsis. The genus Eubacterium eligens group (OR=1.34, 95% CI: 1.11 to 1.63, P=0.0029, q=0.1881) was positively associated with the risk of sepsis. Sepsis may be a significant risk factor for genus Odoribacter (OR=1.18, 95% CI: 1.10 to 1.39, P=0.0415, q=0.9849) and Phascolarctobacterium (OR=1.21, 95% CI: 1.00 to 1.46, P=0.0471, q=0.9849), but this effect was not statistically significant after false discovery rate correction. There was a suggestive association between sepsis and Faecalibacterium (OR=0.85, 95% CI: 0.73 to 0.98, P=0.0278) and Ruminococcus 1 (OR=0.85, 95% CI: 0.73 to 1.00, P=0.0439), which were not significant after false discovery rate correction (q>0.2).

Conclusions

This study found that class Lentisphaeria, order Victivallales, and genus Eubacterium eligens group may have a causal relationship with the risk of sepsis.

Huang Lian Jie Du decoction attenuates inflammation in septic rats by activating autophagy and altering the intestinal microbiome

Aims

The aim of this study was to investigate the protective effect of HLJDD on septic rats and the underlying mechanisms.

Materials and methods

Adult male Sprague-Dawley (SD) adult rats (150-180 g) were randomly divided into the following 5 groups (n = 7 per group): the Sham group, caecal ligation and puncture (CLP) group, HLJDD + CLP (Huang Lian Jie Du Decoction, HLJDD) group (1 g/mL/100 g), HLJDD + Rap + CLP (H. Rap) group (Rap: 3 mg/kg), and HLJDD+3-MA + CLP (H. 3-MA) group (3-MA: 30 mg/kg). Rapamycin (Rap) and 3-methyladenosine (3-MA) were used to activate and inhibit autophagy, respectively. HLJDD was purchased from Beijing Tong Ren Tang Guiyang Branch and verified by experts as a genuine product. We used CLP to establish an animal model of sepsis in the last four groups. Survival was analysed by the Kaplan‒Meier method. Then, we examined autophagy-related genes (Atgs) and proteins using real-time PCR and Western blotting, respectively. The microstructure of the ileum and the number of autophagosomes were observed by transmission electron microscopy (TEM). Analyses of HE-stained pathological ileum and inflammatory factor levels were examined to assess the extent of septic injury. The effect of HLJDD on the gut microbiota was analysed by 16S rRNA gene sequencing of faeces.

Results

In this study, we identified the protective effects of HLJDD on mortality and inflammation in septic rats. Several key proteins, including LC3-II, Beclin-1 and p62, were examined and showed that HLJDD could effectively reverse the sepsis-induced decrease in autophagy. TEM was performed and the expression of Atgs was assessed to evaluate fluctuations in autophagy. Then, we examined the intestinal tight junction protein zona occludens (ZO-1), lipopolysaccharide (LPS) and inflammatory factors, and found that HLJDD effectively alleviated the increase in ZO-1 gene expression, the level of LPS and serum level of inflammatory factors caused by sepsis. These results were consistent with those obtained from pathological sectioning and TEM analysis. Moreover, autophagy activation effectively ameliorated sepsis, and autophagy inhibition exacerbated the systemic symptoms caused by infection. By examining the expression of key proteins upstream of the autophagy pathway, we found that HLJDD inhibited mTOR via the MAPK/PI3K signalling pathway to promote autophagy in septic rats. 16S rRNA sequencing revealed that HLJDD significantly affected the diversity and physiological function of the gut microbiota in septic rats.

Conclusions

The results of this study indicate that autophagy activation is a potential mechanism underlying the protective effect of HLJDD on the intestine in septic rats.

Combination therapy with probiotics and anti-PD-L1 antibody synergistically ameliorates sepsis in mouse model

The study investigated the protective effects and mechanisms of probiotics in conjunction with an anti-PD-L1 antibody on the immune functions of septic mice. Sixty-four mice were assigned to sepsis groups receiving vehicle, probiotics, and anti-PD-L1 antibody individually or in combination, with healthy mice as controls. Sepsis was induced by cecal ligation and puncture (CLP), followed by intraperitoneal Lipopolysaccharide (LPS) injection. Blood and tissues were collected one day post-injection for detecting inflammation-related cytokines, Treg, PI3K/Akt pathway-related protein expression, and lung tissue pathology. The survival time of the remaining ten mice was recorded over seven days. Compared to healthy mice, septic mice given PBS exhibited significantly different serum levels of IL-6, IL-8, IL-17, IL-10, and IFN-γ (all p < 0.001). Treatment with anti-PD-L1 antibody combined with probiotics significantly increased the 7-day survival rate in septic mice, accompanied by decreased pro-inflammatory cytokines, increased anti-inflammatory cytokines, improved oxidative stress, reduced lung injury, and enhanced Th17/Treg balance. This combined therapy demonstrated superior efficacy compared to antibodies or probiotics alone. Additionally, it facilitated peripheral blood polymorphonuclear neutrophil apoptosis, enhancing protection by blocking PD-L1 function and inhibiting PI3K-dependent AKT phosphorylation. In conclusion, combining probiotics with an anti-PD-L1 antibody enhances protective effects in septic mice by reducing serum inflammatory factors, promoting neutrophil apoptosis, regulating Th17/Treg balance, and inhibiting the PI3K/Akt pathway.

[Association between the structure of intestinal flora and inflammatory response in children with sepsis: a prospective cohort study]

OBJECTIVES

To investigate the structural characteristics of intestinal flora in children with sepsis and its association with inflammatory response.

METHODS

A prospective cohort study was conducted. The children with sepsis who were admitted from December 2021 to January 2023 were enrolled as the sepsis group, and the children with non-sepsis who were admitted during the same period were enrolled as the non-sepsis group. The two groups were compared in terms of the distribution characteristics of intestinal flora, peripheral white blood cell count (WBC), C reactive protein (CRP), and cytokines, and the correlation of the relative abundance of fecal flora with WBC, CRP, and cytokines was analyzed.

RESULTS

At the genus level, compared with the non-sepsis group, the sepsis group had significantly lower relative abundance of Akkermansia, Ruminococcus, and Alistipes and significantly higher relative abundance of Enterococcus, Streptococcus, and Staphylococcus (P<0.05). At the phylum level, Proteobacteria was the dominant phylum (37.46%) in the group of children with a score of ≤70 from the Pediatric Critical Illness Score (PICS), and Firmicutes was the dominant phylum in the group of children with a score of 71-80 or 81-90 from the PICS (72.20% and 43.88%, respectively). At the genus level, among the 18 specimens, 5 had a relative abundance of >50% for a single flora. Compared with the non-sepsis group, the sepsis group had significant higher levels of WBC, CRP, interleukin-6 (IL-6), interleukin-10 (IL-10), and tumor necrosis factor-α (P<0.05). The Spearman's rank correlation analysis showed that at the genus level, the relative abundance of Ruminococcus, Alistipes, and Parasutterella in the sepsis group was negatively correlated with the levels of WBC, CRP, and IL-6 (P<0.05); the relative abundance of Enterococcus was positively correlated with the CRP level (P<0.01); the relative abundance of Streptococcus and Staphylococcus was positively correlated with the levels of CRP and IL-6 (P<0.05); the relative abundance of Streptococcus was positively correlated with WBC (P<0.05).

CONCLUSIONS

Intestinal flora disturbance is observed in children with sepsis, and its characteristics vary with the severity of the disease. The structural changes of intestinal flora are correlated with inflammatory response in children with sepsis.

A Mendelian Randomization Study: Roles of Gut Microbiota in Sepsis - Who is the Angle?

Gut microbiota (GM) is a crucial underlying player during sepsis pathogenesis. However, the causal relationship is unclear and remains to be determined. A two-sample Mendelian randomization study was implemented. The statistical data about sepsis together with GM summarized from genome-wide association studies were evaluated. Instrumental variables were defined as single-nucleotide polymorphisms with prominent correlations with exposure. The inverse-variance-weighted test was employed as a major approach of Mendelian randomization analysis to estimate of causal relationships. The inverse-variance-weighted analysis results demonstrated that at different taxa levels, Actinobacteria and Bifidobacteriaceae influence sepsis. Actinobacteria had negative relationships to sepsis risk at the phylum (β = -0.34, SE = 0.10, p = 0.0008) and class (β = -0.23, SE = 0.07, p = 0.0011) levels in outcome coded ieu-b-69. Actinobacteria at the phylum level (β = -0.22, SE = 0.10, p = 0.027) was also negatively associated with sepsis in outcome coded ieu-b-4980. Bifidobacteriaceae at the order (β = -0.20, SE = 0.06, p = 0.0021), family (β = -0.20, SE = 0.06, p = 0.0021), and genus (β = -0.20, SE = 0.06, p = 0.0007) levels were all negatively correlated with the risk of sepsis in outcome coded ieu-b-69. The results of the Wald ratio model showed that Tyzzerella genus (OR (95%CI) = 0.6902[0.4907,0.9708], p = 0.0331) and Gastranaerophilales order (OR (95%CI) = 0.5907[0.3516,0.9926], p = 0.0468) were negatively connected with sepsis. This study implied at different taxa levels Actinobacteria and Bifidobacteriaceae, Tyzzerella genus, and Gastranaerophilales order have a causal relationship with sepsis, indicating that they are protective factors for the incidence of sepsis.

Application of bacteriophage φPaP11-13 attenuates rat Cutibacterium acnes infection lesions by promoting keratinocytes apoptosis via inhibiting PI3K/Akt pathway

Acne vulgaris caused by antibiotic-resistant Cutibacterium acnes (C. acnes) infection is difficult to treat conventionally. Phages have been suggested as a potential solution, but research on the mechanism of phage treatment is inadequate. This research investigates the underlying molecular mechanisms of phage φPaP11-13 attenuating C. acnes-induced inflammation in rat models. We found that rats infected with C. acnes had higher average ear thickness, greater enrichment of inflammatory cells as shown by hematoxylin-eosin (HE) staining, and fewer TUNEL (TdT-mediated dUTP Nick-End Labeling)-positive keratinocytes visualized by IF staining. Moreover, an increase of IGF-1 and IGF-1 receptor (IGF-1r) was detected using the immunohistochemical (IHC) staining method, Western blot (WB), and quantitative real-time PCR (qRT-PCR) when infected with C. acnes, which was decreased after the application of phage φPaP11-13. By applying the IGF-1 antibody, it was demonstrated that the severity of C. acnes-induced inflammation was relevant to the expression of IGF-1. Through WB and qRT-PCR, activation of the PI3K/Akt pathway and a down-regulation of the BAD-mediated apoptosis pathway were discovered after C. acnes infection. Subsequently, it was shown that the activation of the PI3K/Akt pathway against BAD-mediated apoptosis pathway was alleviated after applying phage φPaP11-13. Furthermore, applying the IGF-1r inhibitor, Pan-PI3K inhibitor, and Akt inhibitor reversed the changing trends of BAD induced by C. acnes and phage φPaP11-13. This study demonstrates that one of the critical mechanisms underlying the attenuation of acne vulgaris by phage φPaP11-13 is lysing C. acnes and regulating keratinocyte apoptosis via the PI3K/Akt signaling pathway.IMPORTANCECutibacterium acnes infection-induced acne vulgaris may cause severe physical and psychological prognosis. However, the overuse of antibiotics develops drug resistance, bringing challenges in treating Cutibacterium acnes. Bacteriophages are currently proven effective in MDR (multiple drug-resistant) Cutibacterium acnes, but there is a significant lack of understanding of phage therapy. This study demonstrated a novel way of curing acne vulgaris by using phages through promoting cell death of excessive keratinocytes in acne lesions by lysing Cutibacterium acnes. However, the regulation of this cell cycle has not been proven to be directly mediated by phages. The hint of ternary relation among "phage-bacteria-host" inspires huge interest in future phage therapy studies.

Efficacy of probiotics or synbiotics in critically ill patients: A systematic review and meta-analysis

BACKGROUND

This latest systematic review and meta-analysis aim to examine the effects of probiotic and synbiotic supplementation in critically ill patients.

METHODS

Relevant articles were retrieved from PubMed, Embase, the Cochrane Database, and the Web of Science. The primary output measure was the incident of ventilator-associated pneumonia, and the secondary outputs were diarrhea, Clostridium diffusion infection (CDI), incident of sepsis, incident of hospital acquired pneumonia, duration of mechanical exploitation, ICU mortality rate, length of ICU stay, in hospital mortality, and length of hospital stay. Data were pooled and expressed as Relative Risk(RR) and Standardized Mean Difference (SMD) with a 95 % confidence interval (CI).

RESULTS

33 studies were included in this systematic review and meta-analysis, with 4065 patients who received probiotics or synbiotics (treatment group) and 3821 patients who received standard care or placebo (control group). The pooled data from all included studies demonstrated that the treatment group has significantly reduced incidence of ventilation-associated pneumonia (VAP) (RR = 0.80; 95 % CI: 0.67-0.96; p = 0.021, I2 = 52.5 %) and sepsis (RR = 0.97; 95 % CI: 0.66-1.42; p = 0.032, I2 = 54.4 %), As well as significantly increased duration of mechanical exploitation (SMD = -0.47; 95 % CI: -0.74-0.20, p = 0.012, I2 = 63.4 %), ICU mobility (RR = 0.95; 95 % CI: 0.71-1.27; p = 0.004, I2 = 62.8 %), length of ICU stay (SMD = -0.29; 95 % CI: -0.58-0.01; p = 0.000, I2 = 82.3 %) and length of hospital stay (SMD = -0.33; 95 % CI: -0.57-0.08, p = 0.000, I2 = 74.2 %) than the control group. There were no significant differences in diarrhea, CDI, incidence of hospital acquired pneumonia, and in hospital mortality between the two groups.

CONCLUSION

Our meta-analysis showed that probiotic and synbiotic supplements are beneficial for critically ill patients as they significantly reduce the incidence of ventilator associated pneumonia and sepsis, as well as the duration of mechanical exploitation, length of hospital stay, length of ICU stay, and ICU mortality. However, this intervention has minimal impact on diarrhea, CDI, incidence of hospital acquired pneumonia, and in hospital mortality in critically ill patients.

Role of gut microbiota and bacterial translocation in acute intestinal injury and mortality in patients admitted in ICU for septic shock

Introduction

Sepsis is a life-threatening organ dysfunction with high mortality rate. The gut origin hypothesis of multiple organ dysfunction syndrome relates to loss of gut barrier function and the ensuing bacterial translocation. The aim of this study was to describe the evolution of gut microbiota in a cohort of septic shock patients over seven days and the potential link between gut microbiota and bacterial translocation.

Methods

Sixty consecutive adult patients hospitalized for septic shock in intensive care units (ICU) were prospectively enrolled. Non-inclusion criteria included patients with recent or scheduled digestive surgery, having taken laxatives, pre- or probiotic in the previous seven days, a progressive digestive neoplasia, digestive lymphoma, chronic inflammatory bowel disease, moribund patient, and pregnant and lactating patients. The primary objective was to evaluate the evolution of bacterial diversity and richness of gut microbiota during seven days in septic shock. Epidemiological, clinical and biological data were gathered over seven days. Gut microbiota was analyzed through a metagenomic approach. 100 healthy controls were selected among healthy blood donors for reference basal 16S rDNA values.

Results

Significantly lower bacterial diversity and richness was observed in gut microbiota of patients at Day 7 compared with Day 0 (p<0.01). SOFA score at Day 0, Acute Gastrointestinal Injury (AGI) local grade, septic shock origin and bacterial translocation had an impact on alpha diversity. A large increase in Enterococcus genus was observed at Day 7 with a decrease in Enterobacterales, Clostridiales, Bifidobacterium and other butyrate-producing bacteria.

Discussion

This study shows the importance of bacterial translocation during AGI in septic shock patients. This bacterial translocation decreases during hospitalization in ICUs in parallel to the decrease of microbiota diversity. This work highlights the role of gut microbiota and bacterial translocation during septic shock.

The Oxygen-Ozone Adjunct Medical Treatment According to the Protocols from the Italian Scientific Society of Oxygen-Ozone Therapy: How Ozone Applications in the Blood Can Influence Clinical Therapy Success via the Modulation of Cell Biology and Immunity

BACKGROUND

Ozone is an allotrope of oxygen whose use in medicine has rapidly grown in recent years. Ozonated blood allows for the use of ozone in a safe modality, as plasma and blood cells are endowed with an antioxidant system able to quench ozone's pro-oxidant property and to elicit the Nrf2/Kwap1/ARE pathway.

METHODS

We present two clinical studies, a case-series (six patients) observational study adopting ozone as a major autohemotherapy and topical ozone to address infected post-surgical wounds with multi-drug resistant bacteria and an observational study (250 patients) using ozonated blood for treating knee osteoarthritis.

RESULTS

Ozonated blood via major autohemotherapy reduced the extent of infections in wounds, reduced the inflammatory biomarkers by more than 75% and improved patients' QoL, whereas ozonated blood via minor autohemotherapy improved significantly (p < 0.001) WOMAC and Lequesne's parameters in knee osteoarthritis.

CONCLUSIONS

The models described, i.e., ozone autohemotherapy in wound antimicrobial treatment and ozonated blood in knee osteoarthrosis, following our protocols, share the outstanding ability of ozone to modulate the innate immune response and address bacterial clearance as well as inflammation and pain.

Novel tripeptide RKH derived from Akkermansia muciniphila protects against lethal sepsis

OBJECTIVE

The pathogenesis of sepsis is complex, and the sepsis-induced systemic proinflammatory phase is one of the key drivers of organ failure and consequent mortality. Akkermansia muciniphila (AKK) is recognised as a functional probiotic strain that exerts beneficial effects on the progression of many diseases; however, whether AKK participates in sepsis pathogenesis is still unclear. Here, we evaluated the potential contribution of AKK to lethal sepsis development.

DESIGN

Relative abundance of gut microbial AKK in septic patients was evaluated. Cecal ligation and puncture (CLP) surgery and lipopolysaccharide (LPS) injection were employed to establish sepsis in mice. Non-targeted and targeted metabolomics analysis were used for metabolites analysis.

RESULTS

We first found that the relative abundance of gut microbial AKK in septic patients was significantly reduced compared with that in non-septic controls. Live AKK supplementation, as well as supplementation with its culture supernatant, remarkably reduced sepsis-induced mortality in sepsis models. Metabolomics analysis and germ-free mouse validation experiments revealed that live AKK was able to generate a novel tripeptide Arg-Lys-His (RKH). RKH exerted protective effects against sepsis-induced death and organ damage. Furthermore, RKH markedly reduced sepsis-induced inflammatory cell activation and proinflammatory factor overproduction. A mechanistic study revealed that RKH could directly bind to Toll-like receptor 4 (TLR4) and block TLR4 signal transduction in immune cells. Finally, we validated the preventive effects of RKH against sepsis-induced systemic inflammation and organ damage in a piglet model.

CONCLUSION

We revealed that a novel tripeptide, RKH, derived from live AKK, may act as a novel endogenous antagonist for TLR4. RKH may serve as a novel potential therapeutic approach to combat lethal sepsis after successfully translating its efficacy into clinical practice.

Protective effect of hydrangenol on lipopolysaccharide-induced endotoxemia by suppressing intestinal inflammation

Hydrangenol, a dihydroisocoumarin, isolated from the leaves of Hydrangea serrata, possesses anti-inflammatory, anti-obesity, and anti-photoaging activities. In this study, we investigated the protective effects of hydrangenol (HG) against lipopolysaccharide (LPS)-induced endotoxemia and elucidated the underlying molecular mechanisms of action in C57BL/6 mice. Oral administration of HG (20 or 40 mg/kg) significantly restored the survival rate and population of macrophages, T helper cells (CD3+/CD4+), and Th17 cells (CD3+/CD4+/CCR6+) in the spleens of mice with LPS-induced endotoxemia. HG suppressed the expression of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin (IL)-6, IL-1β, and Interferon (IFN)-γ and the mRNA and protein expressions of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) in the intestine and lung of LPS-treated mice. Molecular data showed that HG ameliorated the activation of nuclear factor kappa B (NF-κB) p65, signal transducers and activators of transcription 3 (STAT3), and c-Fos and c-Jun (AP-1 subunits) via the myeloid differentiation primary response 88 (MyD88) dependent toll-like receptor 4 (TLR4) signaling pathway in the LPS-treated mouse intestines. HG treatment caused the recovery of LPS-induced impaired tight junction (occludin and claudin-2) protein and mRNA expressions. Furthermore, HG improved LPS-induced gut dysbiosis in mice. Taken together, our results suggest that HG protects against LPS-induced endotoxemia by restoring immune cells and the capacity of the intestinal barrier, reducing intestinal inflammation, and improving the composition of the gut microbiota.

Investigation of Gut Microbiota Disorders in Sepsis and Sepsis Complicated with Acute Gastrointestinal Injury Based on 16S rRNA Genes Illumina Sequencing

Background

Sepsis is a life-threatening organ dysfunction caused by the host's dysfunctional response to infection, which can cause acute gastrointestinal injury (AGI). The gut microbiota is dynamic and plays a role in the immune and metabolic. The aim of this study was to investigate the composition and function of gut microbiota in patients with sepsis, as well as the gut microbiome that may be involved in the occurrence of AGI.

Methods

A total of 23 stool samples from healthy control individuals and 41 stool samples from sepsis patients were collected. Patients with sepsis were followed up for one week to observe whether AGI has occurred. Finally, 41 patients included 21 sepsis complicated with AGI (referred to as Com-AGI) and 20 sepsis without complicated with AGI (referred to as No-AGI). The gut microbiota was analyzed by 16S rRNA gene sequencing, followed by composition analysis, difference analysis, correlation analysis, functional prediction analysis.

Results

The diversity and evenness of gut microbiota were decreased in patients with sepsis. Compared with No-AGI, the gut microbiota of Com-AGI has higher community diversity, richness, and phylogenetic diversity. Escherichia-Shigella, Blautia and Enterococcus may be important indicators of sepsis. The correlation analysis showed that aspartate aminotransferase (AST) and Barnesiella have the most significant positive correlation. Moreover, Clostridium_innocuum_group, Christensenellaceae_R-7_group and Eubacterium were all significantly correlated with LAC and DAO. Clostridium_innocuum_group, Barnesiella, Christensenellaceae_R-7_group and Eubacterium may play important roles in the occurrence of AGI in sepsis. PICRUSt analysis revealed multiple functional pathways involved in the relationship between gut microbiota and sepsis, including starch degradation V, glycogen degradation I (bacterial), Lipoic acid metabolism and Valine, leucine and isoleucine biosynthesis. BugBase analysis showed that the gut microbiota with Aerobic phenotype may play an important role in sepsis.

Conclusion

Dysfunction of gut microbiota was associated with sepsis and AGI in patients with sepsis.

Lung protection of Chimonanthus nitens Oliv. essential oil driven by the control of intestinal disorders and dysbiosis through gut-lung crosstalk

This work aimed to investigate whether Chimonanthus nitens Oliv. essential oil (CEO)-mediated lung protection was implicated in gut-lung crosstalk. Results showed that CEO attenuated lung and intestinal impairment by improving histopathological changes and inhibiting TLR4/NF-κB signaling pathway in LPS-stimulated rats, suggesting that there might be a mechanism for its lung protection involved in gut-lung interaction through manipulating the overlap in pathological changes via the similar inflammatory response. Furthermore, CEO-triggered intestinal protection was in parallel with the mitigation of ROS production, apoptosis, Ca2+ transport and mitochondrial membrane potential loss in vivo, and its intestinal protection was confirmed in vitro through IEC-6 cells. Importantly, a combination with CEO and LPS significantly remodeled gut microbiota composition compared with LPS alone in rats, while no significant impact on lung microbiota. Therefore, CEO-exerted lung protection was linked to gut and lung interactions involvement with the control of intestinal disorders and dysbiosis.

Relationship between gut microbiota dysbiosis and immune indicator in children with sepsis

Sepsis is a life-threatening multiple-organ injury caused by disordered host immune response to microbial infection. However, the correlation between gut microbiota dysbiosis and immune indicators remains unexplored. To address this gap in knowledge, we carried out 16 S rDNA sequencing, analyzed clinical fecal samples from children with sepsis (n = 30) and control children (n = 25), and obtained immune indicators, including T cell subtypes (CD3+, CD3+CD4+, CD3+CD8+, and CD4/CD8), NK cells, cytokines (IL-2, IL-4, IL-6, IL-10, TNF-α and IFN-γ), and immunoglobulin indices (IgA, IgE, IgM and IgG). In addition, we analyzed the correlation between gut microbiota dysbiosis and immune indicators, and evaluated the clinical discriminatory power of discovered bacterial biomarkers. We found that children with sepsis exhibited gut bacterial dysbiosis and low alpha diversity. The Spearman's rank correlation coefficient suggested that Rhodococcus erythropolis had a significantly positive correlation with IFN-γ and CD3+ T cells. Klebsiella pneumoniae and Streptococcus mitis were significantly correlated with NK cells. Bacteroides uniformis was significantly positively correlated with IgM and erythrocyte sedimentation rate, and Eubacterium eligens was significantly positively correlated with IL-4 and CD3+CD8+ T cells. The biomarkers discovered in this study had strong discriminatory power. These changes in the gut microbiome may be closely related to immunologic dysfunction and to the development or exacerbation of sepsis. However, a large sample size is required for verification.

Clinical value of droplet digital PCR in the diagnosis and dynamic monitoring of suspected bacterial bloodstream infections

BACKGROUND

Bloodstream infections (BSIs) represent a significant public health challenge due to their high morbidity and mortality. The clinical prognosis of BSIs is closely related to the timely and accurate diagnosis and the rational use of initial antimicrobials. We aimed to evaluate the clinical value of droplet digital PCR (ddPCR) in rapid diagnosis and dynamic monitoring of BSIs.

METHODS

In this prospective study, using a ddPCR-based approach which detects 18 common pathogens, we compared the detection results and clinical concordance rates of ddPCR with blood culture (BC) in 211 patients with suspected BSIs. Further, the inflammatory profile of BSIs with Gram-negative bacteria was analyzed by Olink proteomics platform.

RESULTS

Our data showed that the positive detection rate of ddPCR was 48.82%, which was higher than that of BC (9.48%). For BC-validated BSIs, ddPCR had a sensitivity of 90.00% and a specificity of 55.50%. When considering clinically-validated BSIs, the diagnostic value of ddPCR improved with a sensitivity of 92.59% and a specificity of 78.46%.The bacterial load detected by ddPCR was correlated with traditional clinical inflammatory indicators such as interleukin-6 (IL-6) and C-reactive protein (CRP). In addition, using Olink proteomics platform, we revealed that serological osteoprotegerin (OPG), interleukin-8 (IL-8), interleukin-18 receptor 1 (IL-18R1), C-C motif chemokine 20 (CCL20) and IL-6 were substantially elevated in Gram-negative bacteria-associated BSIs, which could serve as novel auxiliary diagnostic indicators for Gram-negative bacteria BSIs.

CONCLUSION

ddPCR has the potential to provide early pathogen diagnosis, dynamic monitoring, and treatment regimen optimization for patients with BSIs.

Erythropoietin-mediated IL-17 F attenuates sepsis-induced gut microbiota dysbiosis and barrier dysfunction

Septic gut damage is critical in the progression of sepsis and multiple organ failure, characterized by gut microbiota dysbiosis and epithelium deficiency in the gut barrier. Recent studies highlight the protective effects of Erythropoietin (EPO) on multiple organs. The present study found that EPO treatment significantly alleviated the survival rate, suppressed inflammatory responses, and ameliorated intestine damage in mice with sepsis. EPO treatment also reversed sepsis-induced gut microbiota dysbiosis. The protective role of EPO in the gut barrier and microbiota was impaired after EPOR knockout. Notably, we innovatively demonstrated that IL-17 F screened by transcriptome sequencing could ameliorate sepsis and septic gut damage including gut microbiota dysbiosis and barrier dysfunction, which was verified by IL-17 F-treated fecal microbiota transplantation (FMT) as well. Our findings highlight the protection effects of EPO-mediated IL-17 F in sepsis-induced gut damage by alleviating gut barrier dysfunction and restoring gut microbiota dysbiosis. EPO and IL-17 F may be potential therapeutic targets in septic patients.

The profile of key gut microbiota members and short-chain fatty acids in patients with sepsis

Sepsis is a complex clinical disorder with heterogeneous etiological factors. Given its high mortality rate, it is considered a global health issue. Recently, the link between gut microbiota and their metabolites, especially short-chain fatty acids, in the pathophysiology of sepsis has been reported. However, there are few findings to confirm this relationship. This study aimed to evaluate some key gut microbiota members, pathogenic bacteria, and short-chain fatty acids in non-ICU patients with sepsis caused by bacteremia compared to a control group. In this case-control study, 45 stool samples from patients with sepsis and 15 healthy persons were collected from October 2021 to August 2022 in Tabriz, Iran. The position of some gut microbiota members and the main short-chain fatty acids concentration were assessed in the two groups by the Q-PCR and the high-performance liquid chromatography system. Faecalibacterium prausnitzii and Bifidobacterium sp. As bacterial with protective features in non-ICU patients with sepsis decreased significantly. Moreover, the concentrations of acetic acid and propionic acid significantly decreased in this group compared to the healthy volunteers. In contrast, the pathogenic bacteria members such as Enterobacteriaceae and Bacteroides sp. Increased significantly in the patients compared to the healthy individuals. The concentration of butyric acid decreased in the patients, but this change was not significant in the two groups. Protective and immune functions of F. prausnitzii and Bifidobacterium sp., as well as acetate and propionate, are evident. In this investigation, this profile was significantly reduced in non-ICU patients with sepsis compared to the control group.

An overview of host-derived molecules that interact with gut microbiota

The gut microbiota comprises bacteria, archaea, fungi, protists, and viruses that live together and interact with each other and with host cells. A stable gut microbiota is vital for regulating host metabolism and maintaining body health, while a disturbed microbiota may induce different kinds of disease. In addition, diet is also considered to be the main factor that influences the gut microbiota. The host could shape the gut microbiota through other factors. Here, we reviewed the mechanisms that mediate host regulation on gut microbiota, involved in gut-derived molecules, including gut-derived immune system molecules (secretory immunoglobulin A, antimicrobial peptides, cytokines, cluster of differentiation 4+ effector T cell, and innate lymphoid cells), sources related to gut-derived mucosal molecules (carbon sources, nitrogen sources, oxygen sources, and electron respiratory acceptors), gut-derived exosomal noncoding RNA (ncRNAs) (microRNAs, circular RNA, and long ncRNA), and molecules derived from organs other than the gut (estrogen, androgen, neurohormones, bile acid, and lactic acid). This study provides a systemic overview for understanding the interplay between gut microbiota and host, a comprehensive source for potential ways to manipulate gut microbiota, and a solid foundation for future personalized treatment that utilizes gut microbiota.

The leaky gut and the gut microbiome in sepsis - targets in research and treatment

Both a leaky gut (a barrier defect of the intestinal surface) and gut dysbiosis (a change in the intestinal microbial population) are intrinsic to sepsis. While sepsis itself can cause dysbiosis, dysbiosis can worsen sepsis. The leaky gut syndrome refers to a status with which there is an increased intestinal permeability allowing the translocation of microbial molecules from the gut into the blood circulation. It is not just a symptom of gastrointestinal involvement, but also an underlying cause that develops independently, and its presence could be recognized by the detection, in blood, of lipopolysaccharides and (1→3)-β-D-glucan (major components of gut microbiota). Gut-dysbiosis is the consequence of a reduction in some bacterial species in the gut microbiome, as a consequence of intestinal mucosal immunity defect, caused by intestinal hypoperfusion, immune cell apoptosis, and a variety of enteric neuro-humoral-immunity responses. A reduction in bacteria that produce short-chain fatty acids could change the intestinal barriers, leading to the translocation of pathogen molecules, into the circulation where it causes systemic inflammation. Even gut fungi might be increased in human patients with sepsis, even though this has not been consistently observed in murine models of sepsis, probably because of the longer duration of sepsis and also antibiotic use in patients. The gut virobiome that partly consists of bacteriophages is also detectable in gut contents that might be different between sepsis and normal hosts. These alterations of gut dysbiosis altogether could be an interesting target for sepsis adjuvant therapies, e.g., by faecal transplantation or probiotic therapy. Here, current information on leaky gut and gut dysbiosis along with the potential biomarkers, new treatment strategies, and future research topics are mentioned.

Gut microbiota involved in myocardial dysfunction induced by sepsis

Myocardial dysfunction is an important complication of sepsis and an important cause of death in sepsis patients. Sepsis will significantly change the composition of gut microbiota, and the destruction of gut microbiota also creates conditions for the occurrence and progression of sepsis. Gut microbiota is an important player in myocardial injury in sepsis. This review elaborates on the possible mechanisms of gut microbiota affecting myocardial injury in sepsis, including short-chain fatty acids, trimethylamine and trimethylamine oxides, various cytokines, and mitochondrial dysfunction. A better understanding of the mechanism could help improve the treatment of sepsis and get a better prognosis for sepsis patients.

Composition and changes of blood microbiota in adult patients with community-acquired sepsis: A pilot study from bench to bedside

Background

Characteristics of the blood microbiota among adult patients with community-acquired sepsis are poorly understood. Our aim was to analyze the composition of blood microbiota in adult patients with community-acquired sepsis, and correlate changes with non-septic control patients.

Methods

A prospective observational study was carried out by including adult patients hospitalized for community-acquired sepsis at our center between January and November 2019, by random selection from a pool of eligible patients. Study inclusion was done on the day of sepsis diagnosis. Community acquisition was ascertained by a priori exclusion criteria; sepsis was defined according to the SEPSIS-3 definitions. Each included patient was matched with non-septic control patients by age and gender in a 1:1 fashion enrolled from the general population. Conventional culturing with BacT/ALERT system and 16S rRNA microbiota analysis were performed from blood samples taken in a same time from a patient. Abundance data was analyzed by the CosmosID HUB Microbiome software.

Results

Altogether, 13 hospitalized patients were included, 6/13 (46.2%) with sepsis and 7/13 (53.8%) with septic shock at diagnosis. The most prevalent etiopathogen isolated from blood cultures was Escherichia coli, patients mostly had intraabdominal septic source. At day 28, all-cause mortality was 15.4% (2/13). Compared to non-septic control patients, a relative scarcity of Faecalibacterium, Blautia, Coprococcus and Roseburia genera, with an abundance of Enhydrobacter, Pseudomonas and Micrococcus genera was observed among septic patients. Relative differences between septic vs. non-septic patients were more obvious at the phylum level, mainly driven by Firmicutes (25.7% vs. 63.1%; p<0.01) and Proteobacteria (36.9% vs. 16.6%; p<0.01). The alpha diversity, quantified by the Chao1 index showed statistically significant difference between septic vs. non-septic patients (126 ± 51 vs. 66 ± 26; p<0.01). The Bray-Curtis beta diversity, reported by principal coordinate analysis of total hit frequencies, revealed 2 potentially separate clusters among septic vs. non-septic patients.

Conclusion

In adult patients with community-acquired sepsis, specific changes in the composition and abundance of blood microbiota could be detected by 16S rRNA metagenome sequencing, compared to non-septic control patients. Traditional blood culture results only partially correlate with microbiota test results.

Gut microbiota-derived indole 3-propionic acid partially activates aryl hydrocarbon receptor to promote macrophage phagocytosis and attenuate septic injury

Sepsis is associated with a high risk of death, and the crosstalk between gut microbiota and sepsis is gradually revealed. Indole 3-propionic acid (IPA) is a gut microbiota-derived metabolite that exerts immune regulation and organ protective effects. However, the role of IPA in sepsis is not clear. In this study, the role of IPA in sepsis-related survival, clinical scores, bacterial burden, and organ injury was assessed in a murine model of cecal ligation and puncture-induced polymicrobial sepsis. Aryl hydrocarbon receptor (AhR) highly specific inhibitor (CH223191) was used to observe the role of AhR in the protection of IPA against sepsis. The effects of IPA on bacterial phagocytosis by macrophages were investigated in vivo and vitro. The levels of IPA in feces were measured and analyzed in human sepsis patients and patient controls. First, we found that gut microbiota-derived IPA was associated with the survival of septic mice. Then, in animal model, IPA administration protected against sepsis-related mortality and alleviated sepsis-induced bacterial burden and organ injury, which was blunted by AhR inhibitor. Next, in vivo and vitro, IPA enhanced the macrophage phagocytosis through AhR. Depletion of macrophages reversed the protective effects of IPA on sepsis. Finally, on the day of ICU admission (day 0), septic patients had significantly lower IPA level in feces than patient controls. Also, septic patients with bacteremia had significantly lower IPA levels in feces compared with those with non-bacteremia. Furthermore, in septic patients, reduced IPA was associated with worse clinical outcomes, and IPA in feces had similar prediction ability of 28-day mortality with SOFA score, and increased the predictive ability of SOFA score. These findings indicate that gut microbiota-derived IPA can protect against sepsis through host control of infection by promoting macrophages phagocytosis and suggest that IPA may be a new strategy for sepsis treatment.

Traditional Chinese Medicine: A promising strategy to regulate inflammation, intestinal disorders and impaired immune function due to sepsis

Sepsis is described as a dysregulation of the immune response to infection, which leads to life-threatening organ dysfunction. The interaction between intestinal microbiota and sepsis can't be ignored. Furthermore, the intestinal microbiota may regulate the progress of sepsis and attenuate organ damage. Thus, maintaining or restoring microbiota may be a new way to treat sepsis. Traditional Chinese medicine (TCM) assumes a significant part in the treatment of sepsis through multi-component, multi-pathway, and multi-targeting abilities. Moreover, TCM can prevent the progress of sepsis and improve the prognosis of patients with sepsis by improving the imbalance of intestinal microbiota, improving immunity and reducing the damage to the intestinal barrier. This paper expounds the interaction between intestinal microbiota and sepsis, then reviews the current research on the treatment of sepsis with TCM, to provide a theoretical basis for its clinical application.

Contribution of gut microbiota toward renal function in sepsis

Sepsis most often involves the kidney and is one of the most common causes of acute kidney injury. The prevalence of septic acute kidney injury has increased significantly in recent years. The gut microbiota plays an important role in sepsis. It interacts with the kidney in a complex and multifactorial process, which is not fully understood. Sepsis may lead to gut microbiota alteration, orchestrate gut mucosal injury, and cause gut barrier failure, which further alters the host immunological and metabolic homeostasis. The pattern of gut microbiota alteration also varies with sepsis progression. Changes in intestinal microecology have double-edged effects on renal function, which also affects intestinal homeostasis. This review aimed to clarify the interaction between gut microbiota and renal function during the onset and progression of sepsis. The mechanism of gut–kidney crosstalk may provide potential insights for the development of novel therapeutic strategies for sepsis.

Indole-3-Propionic Acid as a Potential Therapeutic Agent for Sepsis-Induced Gut Microbiota Disturbance

The effects of using gut microbiota metabolites instead of live microorganisms to modulate sepsis-induced gut dysbiosis remain largely unknown. We assessed the effects of microbiota metabolite indole-3-propionic acid (IPA) on gut microbiota in mice during sepsis. Sepsis models were constructed by cecal ligation and puncture (CLP) methods. Fecal microbiota composition analysis was performed to characterize the gut microbiota composition. Fecal microbiota transplantation was performed to validate the roles of gut microbiota on sepsis progression. IPA-treated mice exhibited lower serum inflammatory mediator levels and a higher survival rate than those of saline-treated mice after modeling of sepsis, which were negated in the presence of antibiotics. Compared with saline-treated mice after modeling, IPA-treated mice showed a markedly different intestinal microbiota composition, with an enrichment of Bifidobacteriaceae family and a depletion of Enterobacteriaceae family. Mice gavaged with postoperative feces from IPA-treated animals displayed better survival than mice gavaged with feces from saline-treated animals. Overall, these data suggest that IPA offers a microbe-modulated survival advantage in septic mice, indicating that some microbiota metabolites could replace live microorganisms as potential options for regulation of sepsis-induced gut dysbiosis. IMPORTANCE The role of gut microbiota in the pathophysiology of sepsis is gaining increasing attention and developing effective and safe sepsis therapies targeting intestinal microorganisms is promising. Given the safety of probiotic supplementation or fecal microbiota transplantation in critically ill patients, identifying an abiotic agent to regulate the intestinal microbiota of septic patients is of clinical significance. This study revealed that IPA, a microbiota-generated tryptophan metabolite, ameliorated sepsis-induced mortality and decreased the serum levels of proinflammatory cytokines by modulating intestinal microbiota. Although IPA did not increase the abundance and diversity of the microbiota of septic mice, it significantly decreased the number of Enterobacteriaceae family. These findings indicate that a specific microbiota metabolite (e.g., IPA) can mediate the intestinal microbiota apart from FMT or probiotics.