Enteric dysbiosis is associated with sepsis in patients

Tongfu Lifei Decoction Attenuated Sepsis-Related Intestinal Mucosal Injury Through Regulating Th17/Treg Balance and Modulating Gut Microbiota

Intestinal damage and secondary bacterial translocation are caused by the inflammatory response induced by sepsis. Tongfu Lifei (TLF) decoction has a protective effect on sepsis-related gastrointestinal function injury. However, the relation between gut microbiota, immune barrier, and sepsis under the treatment of TLF have not been well clarified yet. Here, rats were subjected to cecal ligation and puncture (CLP) to create a sepsis model. Subsequently, the TLF decoction was given to CLP rats by gavage, fecal microbiota transplantation (FMT), and antibiotic were used as positive control. TLF suppressed the inflammatory response and improved the pathological changes in the intestines of CLP rats. Besides, TLF promoted the balance of the percentage of the Th17 and Treg cells. Intestinal barrier function was also improved by TLF through enhancing ZO-1, and Occludin and Claudin 1 expression, preventing the secondary translocation of other gut microbiota. TLF dramatically boosted the gut microbiota's alpha- and beta-diversity in CLP rats. Moreover, it increased the relative abundance of anti-inflammatory gut microbiota and changed the progress of the glucose metabolism. In short, TLF regulated the gut microbiota to balance the ratio of Th17/Treg cells, reducing the inflammation in serum and intestinal mucosal injury in rats.

Analysis of fecal microbiota and related clinical indicators in ICU patients with sepsis

Background

To analyze the characteristics of fecal microbiota disturbance in the intensive care unit (ICU) patients with sepsis and the correlation with related clinical indicators.

Methods

This study included 31 patients with sepsis admitted to the emergency ICU ward between September 2019 and December 2021. They were divided into Group without septic shock (ND_NS group, 7 cases) and Group with septic shock (ND_S group, 24 cases) according to the presence or absence of septic shock. Furthermore, we divided these 31 sepsis patients into Clinical Improvement group (21 cases) and Death or DAMA group (10 cases) based on clinical outcome, 15 cases of Physical Examiner recruited in the same period were included as control group: ND_HC group (15 cases). The fecal samples of the patients with sepsis within 24 h of admission and random fecal samples of the control group were collected and analyzed by 16S rDNA gene sequencing used for the analysis of fecal microbiota. At the same time, the relevant clinical data of these patients with sepsis were also collected for analysis.

Results

There were 15 cases with drug-resistant bacteria in the ND_S group and only 2 cases in the ND_NS group (P = 0.015). There were significant differences in APACHE II score, length of ICU stay, lactate level, and oxygenation index of patients between the Death or DAMA group and Clinical Improvement group (all P < 0.05). For phylum level, the abundance of Firmicutes, Actinobacteria, and Bacteroidetes decreased in the ND group compared with the ND_HC group, while the abundance of Proteobacteria increased (P < 0.05). For genus level, the relative abundance of Escherichia-Shigella and Klebsiella were significantly increased in the ND group compared with the ND_HC group (P < 0.05). The top six genera in relative abundance in the ND_S group were Escherichia-Shigella, Enterococcus, Bifidobacterium, Lactobacillus, Akkermansia, and Klebsiella. Compared with the Clinical Improvement group, the relative abundance of Escherichia-Shigella and Klebsiella in the Death or DAMA group showed an increasing trend with no significant significance, while the relative abundance of Enterococcus and Faecalibacterium decreased in the Death or DAMA group (P < 0.05). Alpha diversity analysis showed that compared with the ND_HC group, the alpha diversity of the fecal microbiota in the ND group decreased. There were significant differences in the Observed_species index, Chao1 index, and ACE index of patients between the ND_HC group and ND group (all P < 0.05). Moreover, compared with the ND_NS group, the Alpha diversity of the ND_S group was more abundant. PCoA analysis showed significant differences in microbial community structure between the ND group and ND_HC group (P = 0.001). There also were significant differences in microbial community structure between the ND_S group and ND_NS group (P = 0.008). LEfSe analysis showed that compared with the ND_HC group, there were significant differences in the species of the ND group, including Enterobacteriaceae, Escherichia-Shigella, Enterococcus, Elizabethkingia, and Family_XIII_AD3011_group.

Conclusions

ICU patients with sepsis suffered intestinal microecological disturbances with significantly decreased abundance of fecal microbiota, diversity, and beneficial symbiotic bacteria. For these patients, the ratio of pathogenic bacteria, including Escherichia-Shigella and Klebsiella increased and became the main bacterial genus in some samples. Moreover, the increasing trend of these two pathogenic bacteria may be correlated with the development of septic shock and the risk of death in patients with sepsis.

Ten good reasons to consider gastrointestinal function after acute brain injury

The brain-gut axis represents a bidirectional communication linking brain function with the gastrointestinal (GI) system. This interaction comprises a top-down communication from the brain to the gut, and a bottom-up communication from the gut to the brain, including neural, endocrine, immune, and humoral signaling. Acute brain injury (ABI) can lead to systemic complications including GI dysfunction. Techniques for monitoring GI function are currently few, neglected, and many under investigation. The use of ultrasound could provide a measure of gastric emptying, bowel peristalsis, bowel diameter, bowel wall thickness and tissue perfusion. Despite novel biomarkers represent a limitation in clinical practice, intra-abdominal pressure (IAP) is easy-to-use and measurable at bedside. Increased IAP can be both cause and consequence of GI dysfunction, and it can influence cerebral perfusion pressure and intracranial pressure via physiological mechanisms. Here, we address ten good reasons to consider GI function in patients with ABI, highlighting the importance of its assessment in neurocritical care.

Dietary carbohydrates regulate intestinal colonization and dissemination of Klebsiella pneumoniae

Bacterial translocation from the gut microbiota is a source of sepsis in susceptible patients. Previous work suggests that overgrowth of gut pathobionts, including Klebsiella pneumoniae, increases the risk of disseminated infection. Our data from a human dietary intervention study found that, in the absence of fiber, K. pneumoniae bloomed during microbiota recovery from antibiotic treatment. We thus hypothesized that dietary nutrients directly support or suppress colonization of this gut pathobiont in the microbiota. Consistent with our study in humans, complex carbohydrates in dietary fiber suppressed the colonization of K. pneumoniae and allowed for recovery of competing commensals in mouse models. In contrast, through ex vivo and in vivo modeling, we identified simple carbohydrates as a limiting resource for K. pneumoniae in the gut. As proof of principle, supplementation with lactulose, a nonabsorbed simple carbohydrate and an FDA-approved therapy, increased colonization of K. pneumoniae. Disruption of the intestinal epithelium led to dissemination of K. pneumoniae into the bloodstream and liver, which was prevented by dietary fiber. Our results show that dietary simple and complex carbohydrates were critical not only in the regulation of pathobiont colonization but also disseminated infection, suggesting that targeted dietary interventions may offer a preventative strategy in high-risk patients.

What we need to know about the germ-free animal models

The gut microbiota (GM), as a forgotten organ, refers to the microbial community that resides in the gastrointestinal tract and plays a critical role in a variety of physiological activities in different body organs. The GM affects its targets through neurological, metabolic, immune, and endocrine pathways. The GM is a dynamic system for which exogenous and endogenous factors have negative or positive effects on its density and composition. Since the mid-twentieth century, laboratory animals are known as the major tools for preclinical research; however, each model has its own limitations. So far, two main models have been used to explore the effects of the GM under normal and abnormal conditions: the isolated germ-free and antibiotic-treated models. Both methods have strengths and weaknesses. In many fields of host-microbe interactions, research on these animal models are known as appropriate experimental subjects that enable investigators to directly assess the role of the microbiota on all features of physiology. These animal models present biological model systems to either study outcomes of the absence of microbes, or to verify the effects of colonization with specific and known microbial species. This paper reviews these current approaches and gives advantages and disadvantages of both models.

Palmatine ameliorated lipopolysaccharide-induced sepsis-associated encephalopathy mice by regulating the microbiota-gut-brain axis

BACKGROUND

Sepsis-associated encephalopathy (SAE), a common neurological complication from sepsis, is widespread among patients in intensive care unit and is linked to substantial morbidity and mortality rates, thus posing a substantial menace to human health. Due to the intricate nature of SAE's pathogenesis, there remains a dearth of efficacious therapeutic protocols, encompassing pharmaceutical agents and treatment modalities, up until the present time. Palmatine exhibits distinctive benefits in the regulation of inflammation for the improvement of sepsis. Nevertheless, the precise functions of palmatine in treating SAE and its underlying mechanism have yet to be elucidated.

PURPOSE

This study aimed to evaluate efficiency of palmatine in SAE mice and its underlying mechanisms.

STUDY DESIGN AND METHODS

Behavioral experiments, percent survival rate analysis, histological analysis, immunofluorescence staining, ELISA analysis, were performed to evaluate the efficiency of palmatine in SAE mice. Quantibody® mouse inflammation array glass chip was performed to observe the effects of palmatine on inflammation storm in SAE mice. Real-time quantitative and western blotting analyzes were employed to examine the expression of relevant targets in the Notch1/nuclear factor-kappa B (NF-κB) pathway. Finally, brain tissues metabolomics-based analyzes were performed to detect the differentially expressed metabolites and metabolic pathways. The fecal samples were subjected to microbial 16S rRNA analysis and untargeted metabolomics analysis in order to identify the specific flora and metabolites associated with SAE, thereby further investigating the mechanism of palmatine in SAE mice.

RESULTS

Our results showed that palmatine significantly improved nerve function, reduced cell apoptosis in brain tissue, and decreased inflammatory cytokine levels in SAE induced-LPS mice. Meanwhile, our results demonstrate the potential of palmatine in modulating key components of the Notch1/NF-κB pathway, enhancing the expression of tight junction proteins, improving intestinal permeability, promoting the growth of beneficial bacteria (such as Lachnospiraceae_NK4A136_group), inhibiting the proliferation of harmful bacteria (such as Escherichia-Shigella), and mitigating metabolic disorders. Ultimately, these observed effects contribute to the therapeutic efficacy of palmatine in treating SAE.

CONCLUSION

The findings of our study have provided confirmation regarding the efficacy of palmatine in the treatment of SAE, thereby establishing a solid foundation for further exploration into SAE therapy and the advancement and investigation of palmatine.

Gut microbiota and sepsis and sepsis-related death: a Mendelian randomization investigation

Background

It is unclear what the causal relationship is between the gut microbiota and sepsis. Therefore, we employed Mendelian randomization (MR) to determine whether a causal link exists between the two.

Methods

This study used publicly available genome-wide association studies (GWAS) summary data of gut microbiota, sepsis, sepsis (critical care), and sepsis (28-day death in critical care) to perform a two-sample MR analysis. To ensure the robustness of the results, we also conducted a sensitivity analysis.

Results

For sepsis susceptibility, inverse variance weighted (IVW) estimates revealed that Victivallales (OR = 0.86, 95% CI, 0.78-0.94, p = 0.0017) was protective against sepsis, while Lentisphaerae (OR = 0.89, 95% CI, 0.80-0.99), Gammaproteobacteria (OR = 1.37, 95% CI, 1.08-1.73), Clostridiaceae1 (OR = 1.21, 95% CI, 1.04-1.40), RuminococcaceaeUCG011 (OR = 1.10, 95% CI, 1.01-1.20), Dialister (OR = 0.85, 95% CI, 0.74-0.97), and Coprococcus2 (OR = 0.81, 95% CI, 0.69-0.94) presented a suggestive association with the development of sepsis (all p < 0.05). For sepsis (critical care), IVW estimates indicated that Lentisphaerae (OR = 0.70, 95% CI, 0.53-0.93), Victivallales (OR = 0.67, 95% CI, 0.50-0.91), Anaerostipes (OR = 0.49, 95% CI, 0.31-0.76), LachnospiraceaeUCG004 (OR = 0.51, 95% CI, 0.34-0.77), and Coprococcus1 (OR = 0.66, 95% CI, 0.44-0.99) showed a suggestive negative correlation with sepsis (critical care) (all p < 0.05). For sepsis (28-day death in critical care), IVW estimates suggested that four bacterial taxa had a normally significant negative correlation with the risk of sepsis-related death, including Victivallales (OR = 0.54, 95% CI, 0.30-0.95), Coprococcus2 (OR = 0.34, 95% CI, 0.14-0.83), Ruminiclostridium6 (OR = 0.43, 95% CI, 0.22-0.83), and Coprococcus1 (OR = 0.45, 95% CI, 0.21-0.97), while two bacterial taxa were normally significantly positively linked to the risk of sepsis-related death, namely, Mollicutes (OR = 2.03, 95% CI, 1.01-4.08) and Bacteroidales (OR = 2.65, 95% CI, 1.18-5.96) (all p < 0.05). The robustness of the above correlations was verified by additional sensitivity analyses.

Conclusion

This MR research found that several gut microbiota taxa were causally linked to the risk of sepsis, sepsis in critical care, and sepsis-related 28-day mortality in critical care.

Potential roles of HSYA in attenuating sepsis-induced liver injury through multi-omics analysis

Liver injury is a strong independent predictor of mortality in patients with sepsis, in which gut dysbiosis plays a crucial role. Hydroxyl safflower yellow A (HSYA), an important component of safflower, has been used to treat liver injury in animal models. However, its role in sepsis-induced liver dysfunction and the specific molecular mechanisms remain unclear. In the current study, we first discussed the discrepancy in the gut microbiota between the cecal ligation puncture (CLP) and HSYA groups using 16 S RNA sequencing. Our data demonstrated that HSYA supplementation significantly decreased the relative abundance of Proteobacteria, Firmicutes, and Campylobacterota, and further decreased the abundance of Bacteroidota, suggesting that the protective effects of HSYA against sepsis-induced liver injury may be partially attributed to the alteration of these bacteria. In addition, the metabolomic data identified 823 differentially expressed metabolites associated with sepsis-induced liver injury. After HSYA supplementation, the levels of 56 metabolites were restored to sham-like levels. Transcriptomic analysis revealed 4990 differentially expressed genes (DEGs) between the sham and CLP groups, and after HSYA injection, 1613 genes were modulated. Comprehensive analysis demonstrated that the enrichment pathways of the 903 DEGs mainly focused on inflammatory responses, amino acid metabolism, and Lipid reactions. In conclusion, our study revealed the potential mechanism of action of HSYA in sepsis-induced liver injury through a comprehensive analysis of 16 S RNA sequencing, metabolomics, and transcriptomics, thus providing a theoretical basis for further clinical applications of HSYA.

Pathogenesis and therapeutic opportunities of gut microbiome dysbiosis in critical illness

For many years, it has been hypothesized that pathological changes to the gut microbiome in critical illness is a driver of infections, organ dysfunction, and other adverse outcomes in the intensive care unit (ICU). The advent of contemporary microbiome methodologies and multi-omics tools have allowed researchers to test this hypothesis by dissecting host-microbe interactions in the gut to better define its contribution to critical illness pathogenesis. Observational studies of patients in ICUs have revealed that gut microbial communities are profoundly altered in critical illness, characterized by markedly reduced alpha diversity, loss of commensal taxa, and expansion of potential pathogens. These key features of ICU gut dysbiosis have been associated with adverse outcomes including life-threatening hospital-acquired (nosocomial) infections. Current research strives to define cellular and molecular mechanisms connecting gut dysbiosis with infections and other outcomes, and to identify opportunities for therapeutic modulation of host-microbe interactions. This review synthesizes evidence from studies of critically ill patients that have informed our understanding of intestinal dysbiosis in the ICU, mechanisms linking dysbiosis to infections and other adverse outcomes, as well as clinical trials of microbiota-modifying therapies. Additionally, we discuss novel avenues for precision microbial therapeutics to combat nosocomial infections and other life-threatening complications of critical illness.

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.

Kazachstania pintolopesii in Blood and Intestinal Wall of Macrophage-Depleted Mice with Cecal Ligation and Puncture, the Control of Fungi by Macrophages during Sepsis

Although macrophage depletion is a possible emerging therapeutic strategy for osteoporosis and melanoma, the lack of macrophage functions can lead to inappropriate microbial control, especially the regulation of intestinal microbiota. Cecal ligation and puncture (CLP) sepsis was performed in regular mice and in mice with clodronate-induced macrophage depletion. Macrophage depletion significantly increased the mortality and severity of sepsis-CLP mice, partly through the increased fecal Ascomycota, especially Kazachstania pintolopesii, with polymicrobialbacteremia (Klebsiella pneumoniae, Enterococcus faecalis, and Acinetobacter radioresistens). Indeed, macrophage depletion with sepsis facilitated gut dysbiosis that directly affected gut permeability as yeast cells were located and hidden in the colon crypts. To determine the interactions of fungal molecules on bacterial abundance, the heat-kill lysate of fungi (K. pintolopesii and C. albicans) and purified (1→3)-β-d-glucan (BG; a major component of the fungal cell wall) were incubated with bacteria that were isolated from the blood of macrophage-depleted mice. There was enhanced cytokine production of enterocytes (Caco-2) after the incubation of the lysate of K. pintolopesii (isolated from sepsis mice), the lysate of C. albicans (extracted from sepsis patients), and BG, together with bacterial lysate. These data support a possible influence of fungi in worsening sepsis severity. In conclusion, macrophage depletion enhanced K. pintolopesii in feces, causing the overgrowth of fecal pathogenic bacteria and inducing a gut permeability defect that additively worsened sepsis severity. Hence, the fecal fungus could be spontaneously elevated and altered in response to macrophage-depleted therapy, which might be associated with sepsis severity.

Causal associations between gut microbiota and sepsis: A two-sample Mendelian randomization study

BACKGROUND

Targeting the gut microbiota may become a new therapeutic to prevent and treat sepsis. Nonetheless, the causal relationship between specific intestinal flora and sepsis is still unclear.

METHODS

A two-sample Mendelian randomization study was performed using the summary statistics of gut microbiota from the largest available genome-wide association study (n = 18,340). The summary statistics of sepsis were obtained from the UK Biobank (n = 486,484). Inverse-variance weighted, weighted median and MR-Egger were used to examine the causal association between gut microbiota and sepsis. Cochrane's Q test, MR-Egger intercept test, MR-PRESSO Global test and Rucker's Q'-test were used for sensitivity analyses. The leave-one method was used for testing the stability of MR results, and Bonferroni-corrected was used to test the strength of the causal relationship between exposure and outcome.

RESULTS

Nine intestinal microflora were found causally associated with sepsis, and 11 intestinal microflora were causally associated with 28-day death in sepsis. Among them, Order Victivallales had a strong causality with lower risk of sepsis (OR = 0.86, 95% CI: 0.78-0.94, p = .00165) and lower 28-day mortality of sepsis (OR = 0.68, 95% CI: 0.53-0.87, p = .00179) after Bonferroni-corrected test. No pleiotropy was detected.

CONCLUSIONS

Through the two-sample MR analysis, we identified the specific intestinal flora that had a causal relationship with the risk and prognosis of sepsis at the level of gene prediction, which may provide helpful biomarkers for early disease diagnosis and potential therapeutic targets for sepsis.

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.

Role of sphingosine 1-phosphate (S1P) in sepsis-associated intestinal injury

Sphingosine-1-phosphate (S1P) is a widespread lipid signaling molecule that binds to five sphingosine-1-phosphate receptors (S1PRs) to regulate downstream signaling pathways. Sepsis can cause intestinal injury and intestinal injury can aggravate sepsis. Thus, intestinal injury and sepsis are mutually interdependent. S1P is more abundant in intestinal tissues as compared to other tissues, exerts anti-inflammatory effects, promotes immune cell trafficking, and protects the intestinal barrier. Despite the clinical importance of S1P in inflammation, with a very well-defined mechanism in inflammatory bowel disease, their role in sepsis-induced intestinal injury has been relatively unexplored. In addition to regulating lymphocyte exit, the S1P-S1PR pathway has been implicated in the gut microbiota, intestinal epithelial cells (IECs), and immune cells in the lamina propria. This review mainly elaborates on the physiological role of S1P in sepsis, focusing on intestinal injury. We introduce the generation and metabolism of S1P, emphasize the maintenance of intestinal barrier homeostasis in sepsis, and the protective effect of S1P in the intestine. We also review the link between sepsis-induced intestinal injury and S1P-S1PRs signaling, as well as the underlying mechanisms of action. Finally, we discuss how S1PRs affect intestinal function and become targets for future drug development to improve the translational capacity of preclinical studies to the clinic.

Gut microbiota and sepsis: bidirectional Mendelian study and mediation analysis

Background

There is a growing body of evidence that suggests a connection between the composition of gut microbiota and sepsis. However, more research is needed to better understand the causal relationship between the two. To gain a deeper insight into the association between gut microbiota, C-reactive protein (CRP), and sepsis, we conducted several Mendelian randomization (MR) analyses.

Methods

In this study, publicly available genome-wide association study (GWAS) summary statistics were examined to determine the correlation between gut microbiota and sepsis, including various sepsis subgroups (such as under 75, 28-day death, Critical Care Units (ICU), 28-day death in ICU). Initially, two-sample and reverse Mendelian randomization (MR) analyses were conducted to identify causality between gut microbiota and sepsis. Subsequently, multivariable and two-step MR analyses revealed that the relationship between microbiota and sepsis was mediated by CRP. The robustness of the findings was confirmed through several sensitivity analyses.

Findings

In our study, we revealed positive correlations between 24 taxa and different sepsis outcomes, while 30 taxa demonstrated negative correlations with sepsis outcomes. Following the correction for multiple testing, we found that the Phylum Lentisphaerae (OR: 0.932, p = 2.64E-03), class Lentisphaeria, and order Victivallales (OR: 0.927, p = 1.42E-03) displayed a negative relationship with sepsis risk. In contrast, Phylum Tenericutes and class Mollicutes (OR: 1.274, p = 2.89E-03) were positively related to sepsis risk and death within 28 days. It is notable that Phylum Tenericutes and class Mollicutes (OR: 1.108, p = 1.72E-03) also indicated a positive relationship with sepsis risk in individuals under 75. From our analysis, it was shown that C-reactive protein (CRP) mediated 32.16% of the causal pathway from Phylum Tenericutes and class Mollicutes to sepsis for individuals under 75. Additionally, CRP was found to mediate 31.53% of the effect of the genus Gordonibacter on sepsis. Despite these findings, our reverse analysis did not indicate any influence of sepsis on the gut microbiota and CRP levels.

Conclusion

The study showcased the connection between gut microbiota, CRP, and sepsis, which sheds new light on the potential role of CRP as a mediator in facilitating the impact of gut microbiota on sepsis.

Acute gastrointestinal injury and altered gut microbiota are related to sepsis-induced cholestasis in patients with intra-abdominal infection: a retrospective and prospective observational study

Background

Sepsis-associated liver dysfunction (SALD) has high incidence and mortality in patients with intra-abdominal infection (IAI). The associations between acute gastrointestinal injury (AGI), gut microbiota, and SALD were evaluated in patients with IAI.

Methods

A retrospective study was conducted to assess the relationship between AGI and SALD in patients with IAI. Patients were divided into non-SALD and sepsis-induced cholestasis (SIC) groups, which is a subtype of SALD. SIC was defined as total bilirubin >2 mg/dL. AGI incidences between the two groups were compared using Chi-square test. Subsequently, a prospective study was conducted to investigate the gut microbiota differences between patients without SALD and those with SIC. Fecal samples were collected on days 1, 3, and 7 after admission to analyze changes in gut microbiota using 16S ribosomal ribonucleic acid sequencing.

Results

One hundred thirty-four patients with IAI were included retrospectively, with 77 SALD and 57 non-SALD cases. Among patients with SALD, 71 were diagnosed with SIC. Patients with SIC had a higher incidence of AGI compared to those without SALD (28.07% vs. 56.34%, p < 0.05), and a severity-dependent relationship was found between AGI grade and SIC occurrence. Subsequently, 20 patients with IAI were recruited prospectively, with 10 patients each assigned to the non-SALD and SIC groups. Patients with SIC had a more severe gut microbiota disorder on day 7 than those without SALD, including lower microbiota diversities, decreased abundance of Firmicutes and Bacteroidetes, and increased abundance of Proteobacteria and Actinobacteria at the phylum level. Furthermore, Burkholderia - Caballeronia - Paraburkholderia and Delftia, the two most abundant genera, were significantly higher in the SIC group than in the non-SALD group. Functional prediction analysis showed that the top three KEGG pathways were ribosome, pyrimidine metabolism, and the two-component system. During the first week, the abundance of Proteobacteria decreased significantly, whereas Cyanobacteria increased in the non-SALD group; however, the phyla taxa did not change significantly in the SIC group.

Conclusion

There exists a severity-dependent relationship between AGI grade and SIC occurrence in adult patients with IAI. A severe gut microbiota disorder was discovered in SIC during the first week of the intensive care unit stay.

The Potential of Probiotics as Ingestible Adjuvants and Immune Modulators for Antiviral Immunity and Management of SARS-CoV-2 Infection and COVID-19

Probiotic bacteria are able to modulate general antiviral responsiveness, including barrier functionality and innate and adaptive immune responses. The COVID-19 pandemic, resulting from SARS-CoV-2 infection, has created a need to control and treat this viral infection and its ensuing immunopathology with a variety of approaches; one such approach may involve the administration of probiotic bacteria. As with most viral infections, its pathological responses are not fully driven by the virus, but are significantly contributed to by the host's immune response to viral infection. The potential adoption of probiotics in the treatment of COVID-19 will have to appreciate the fine line between inducing antiviral immunity without over-provoking immune inflammatory responses resulting in host-derived immunopathological tissue damage. Additionally, the effect exerted on the immune system by SARS-CoV-2 evasion strategies will also have to be considered when developing a robust response to this virus. This review will introduce the immunopathology of COVID-19 and the immunomodulatory effects of probiotic strains, and through their effects on a range of respiratory pathogens (IAV, SARS-CoV, RSV), as well as SARS-CoV-2, will culminate in a focus on how these bacteria can potentially manipulate both infectivity and immune responsiveness via barrier functionality and both innate and adaptive immunity. In conclusion, the harnessing of induction and augmentation of antiviral immunity via probiotics may not only act as an ingestible adjuvant, boosting immune responsiveness to SARS-CoV-2 infection at the level of barrier integrity and innate and adaptive immunity, but also act prophylactically to prevent infection and enhance protection afforded by current vaccine regimens.

Infiltrated IL-17A-producing gamma delta T cells play a protective role in sepsis-induced liver injury and are regulated by CCR6 and gut commensal microbes

Introduction

Sepsis is a common but serious disease in intensive care units, which may induce multiple organ dysfunctions such as liver injury. Previous studies have demonstrated that gamma delta (γδ) T cells play a protective role in sepsis. However, the function and mechanism of γδ T cells in sepsis-induced liver injury have not been fully elucidated. IL-17A-producing γδ T cells are a newly identified cell subtype.

Methods

We utilized IL-17A-deficient mice to investigate the role of IL-17A-producing γδ T cells in sepsis using the cecum ligation and puncture (CLP) model.

Results

Our findings suggested that these cells were the major source of IL-17A and protected against sepsis-induced liver injury. Flow cytometry analysis revealed that these γδ T cells expressed Vγ4 TCR and migrated into liver from peripheral post CLP, in a CCR6-dependent manner. When CLP mice were treated with anti-CCR6 antibody to block CCR6-CCL20 axis, the recruitment of Vγ4+ γδ T cells was abolished, indicating a CCR6-dependent manner of migration. Interestingly, pseudo germ-free CLP mice treated with antibiotics showed that hepatic IL-17A+ γδ T cells were regulated by gut commensal microbes. E. coli alone were able to restore the protective effect in pseudo germ-free mice by rescuing hepatic IL-17A+ γδ T cell population.

Conclusion

Our research has shown that Vγ4+ IL-17A+ γδ T cells infiltrating into the liver play a crucial role in protecting against sepsis-induced liver injury. This protection was contingent upon the recruitment of CCR6 and regulated by gut commensal microbes.

Metabolomic interplay between gut microbiome and plasma metabolome in cardiac surgery-associated acute kidney injury

RATIONALE

Cardiac surgery-associated acute kidney injury (CSA-AKI) is a prevalent complication of cardiac surgery, which may be associated with a great risk of developing chronic kidney disease and mortality. This study aimed to investigate the possible links between gut microbiota metabolism and CSA-AKI.

METHODS

A prospective cohort of patients who underwent cardiac surgery was continuously recruited, who were further divided into CSA-AKI group and Non-AKI group based on clinical outcomes. Their faecal and plasma samples were collected before surgery and were separately analysed by nontargeted and targeted metabolomics. The differential metabolites related to CSA-AKI were screened out using statistical methods, and altered metabolic pathways were determined by examining the Kyoto Encyclopedia of Genes and Genomes database.

RESULTS

Nearly 1000 faecal metabolites were detected through high-resolution mass spectrometry (MS) and bioinformatics at high and mid confidence levels, and 49 differential metabolites at high confidence level may perform essential biological functions and provide potential diagnostic indicators. Compared with the Non-AKI group, the patients in the CSA-AKI group displayed dramatic changes in gut microbiota metabolism, including amino acid metabolism, nicotinate and nicotinamide metabolism, purine metabolism and ATP-binding cassette (ABC) transporters. Meanwhile, 188 plasma metabolites were identified and quantified by tandem MS, and 34 differential plasma metabolites were screened out between the two groups using univariate statistical analysis. These differential plasma metabolites were primarily enriched in the following metabolic pathways: sulphur metabolism, amino acid biosynthesis, tryptophan metabolism and ABC transporters. Furthermore, the content of indole metabolites in the faecal and plasma samples of the CSA-AKI group was higher than that of the Non-AKI group.

CONCLUSIONS

Patients with CSA-AKI may have dysbiosis of their intestinal microbiota and metabolic abnormalities in their gut system before cardiac surgery. Thus, some metabolites and related metabolic pathways may be potential biomarkers and new therapeutic targets for the disease.

Analysis of Intestinal and Nasopharyngeal Microbiota of Children with Meningococcemia in Pediatric Intensive Care Unit: INMACS-PICU Study

Microbiota composition might play a role in the pathophysiology and course of sepsis, and understanding its dynamics is of clinical interest. Invasive meningococcal disease (IMD) is an important cause of community-acquired serious infection, and there is no information regarding microbiota composition in children with meningococcemia. In this study, we aimed to evaluate the intestinal and nasopharyngeal microbiota composition of children with IMD. Materials and Methods: In this prospective, multi-center study, 10 children with meningococcemia and 10 age-matched healthy controls were included. Nasopharyngeal and fecal samples were obtained at admission to the intensive care unit and on the tenth day of their hospital stay. The V3 and V4 regions of the 16S rRNA gene were amplified following the 16S Metagenomic Sequencing Library Preparation. Results: Regarding the alpha diversity on the day of admission and on the tenth day at the PICU, the Shannon index was significantly lower in the IMD group compared to the control group (p = 0.002 at admission and p = 0.001, on the tenth day of PICU). A statistical difference in the stool samples was found between the IMD group at Day 0 vs. the controls in the results of the Bray-Curtis and Jaccard analyses (p = 0.005 and p = 0.001, respectively). There were differences in the intestinal microbiota composition between the children with IMD at admission and Day 10 and the healthy controls. Regarding the nasopharyngeal microbiota analysis, in the children with IMD at admission, at the genus level, Neisseria was significantly more abundant compared to the healthy children (p < 0.001). In the children with IMD at Day 10, genera Moraxella and Neisseria were decreased compared to the healthy children. In the children with IMD on Day 0, for paired samples, Moraxella, Neisseria, and Haemophilus were significantly more abundant compared to the children with IMD at Day 10. In the children with IMD at Day 10, the Moraxella and Neisseria genera were decreased, and 20 different genera were more abundant compared to Day 0. Conclusions: We first found alterations in the intestinal and nasopharyngeal microbiota composition in the children with IMD. The infection itself or the other care interventions also caused changes to the microbiota composition during the follow-up period. Understanding the interaction of microbiota with pathogens, e.g., N. meningitidis, could give us the opportunity to understand the disease's dynamics.

The modulatory effects of gut microbes and metabolites on blood–brain barrier integrity and brain function in sepsis-associated encephalopathy

Background

Intestinal microbiota homeostasis and the gut-brain axis are key players associated with host health and alterations in metabolic, inflammatory, and neurodegenerative disorders. Sepsis-associated encephalopathy (SAE), which is closely associated with bacterial translocation, is a common secondary organ dysfunction and an urgent, unsolved problem affecting patient quality of life. Our study examined the neuroprotective effects of the gut microbiome and short-chain fatty acid (SCFA) metabolites on SAE.

Methods

Male C57BL/6 mice were administered SCFAs in drinking water, then subjected to cecal ligation and puncture (CLP) surgery to induce SAE. 16S rRNA sequencing was used to investigate gut microbiome changes. The open field test (OFT) and Y-maze were performed to evaluate brain function. The permeability of the blood–brain barrier (BBB) was assessed by Evans blue (EB) staining. Hematoxylin and eosin (HE) staining was used to examine intestinal tissue morphology. The expression levels of tight junction (TJ) proteins and inflammatory cytokines was assessed by western blots and immunohistochemistry. In vitro, bEND.3 cells were incubated with SCFAs and then with lipopolysaccharide (LPS). Immunofluorescence was used to examine the expression of TJ proteins.

Results

The composition of the gut microbiota was altered in SAE mice; this change may be related to SCFA metabolism. SCFA treatment significantly alleviated behavioral dysfunction and neuroinflammation in SAE mice. SCFAs upregulated occludin and ZO-1 expression in the intestine and brain in SAE mice and LPS-treated cerebromicrovascular cells.

Conclusions

These findings suggested that disturbances in the gut microbiota and SCFA metabolites play key roles in SAE. SCFA supplementation could exert neuroprotective effects against SAE by preserving BBB integrity.

[Bacterial gut microbiota-key player in sepsis]

The gut microbiota is comprised of over 1200 different bacteria and forms a symbiotic community with the human organism, the holobiont. It plays an important role in the maintenance of homeostasis, e.g., of the immune system and essential metabolic processes. Disturbances in the balance of this reciprocal relationship are called dysbiosis and, in the field of sepsis, are associated with incidence of disease, extent of the systemic inflammatory response, severity of organ dysfunction, and mortality. In addition to providing guiding principles in the fascinating relationship between "human and microbe," this article summarizes recent findings regarding the role of the bacterial gut microbiota in sepsis, which is one a very relevant in intensive care medicine.

Contributions of the microbiota to the systemic inflammatory response

The health of the intestinal microbiota impacts tolerance at homeostasis and the strength of the inflammation response during acute bloodstream infections. A complete understanding of the feedback loop between systemic inflammation and dysregulation of the gut microbiota is necessary for inflammation management. Here we will review the many ways in which the microbiota can influence the systemic pro-inflammatory response. Short-chain fatty acids, produced through the microbial metabolism of dietary fibers, can suppress inflammation systemically; in the absence of a balanced diet or disruption of the microbiota through antibiotics, there is disrupted metabolite production, leading to systemic inflammation. Dysbiosis or inflammation in the intestines can lead to a breakdown of the sturdy intestinal-epithelial barrier. When this barrier is perturbed, immunogenic lipopolysaccharides or extracellular vesicles enter the bloodstream and induce excessive inflammation. Necessary clinical treatments, such as antifungals or antibacterials, induce microbiota dysregulation and thus increased risk of endotoxemia; though probiotics may aid in improving the microbiota health and have been shown to deflate inflammation during sepsis. Within this complicated relationship: What is in control, the dysbiotic microbiota or the systemic inflammation?

Study on the protective effect of berberine treatment on sepsis based on gut microbiota and metabolomic analysis

Introduction

Sepsis, an infection with multiorgan dysfunction, is a serious burden on human health. Berberine (BBR), a bioactive component, has a protective effect on sepsis and the effect may be related to gut microbiota. However, studies on the role of BBR with gut microbiota in sepsis are lacking. Therefore, this study investigated the ameliorative effects and the underlying mechanisms of BBR on cecal ligature and puncture (CLP) rats.

Methods

This study has observed the effect of BBR on pathological injury, Inflammation, intestinal barrier function, gut microbiota, and metabolite change in CLP rats by Hematoxylin-eosin staining, enzyme-linked immunosorbent assays, flow cytometry, 16S rDNA, and metabolomics analyses.

Results

The inhibition effects of BBR treatment on the histological damage of the lung, kidney, and ileum, the interleukin (IL)-1b, IL-6, IL-17A, and monocyte chemokine-1 levels in serum in CLP rats were proved. Also, the BBR inhibited the diamine-oxidase and fluorescein isothiocyanate-dextran 40 levels, suggesting it can improve intestinal barrier function disorders. The cluster of differentiation (CD) 4⁺, CD8⁺, and CD25⁺ Forkhead box protein P3 (Foxp3) + T lymphocytes in splenocytes were up-regulated by BBR, while the IL-17A+CD4+ cell level was decreased. The abundance of gut microbiota in CLP rats was significantly different from that of the sham and BBR treatment rats. The significantly changed metabolites in the serum mainly included carbohydrates, phenols, benzoic acids, alcohols, vitamins et al. Additionally, this study predicted that the biological mechanism of BBR to ameliorate sepsis involves glycolysis-, nucleotide-, and amino acid-related metabolic pathways.

Discussion

This study proved the strong correlation between the improvement effect of BBR on sepsis and gut microbiota and analyzed by metabolomics that gut microbiota may improve CLP rats through metabolites, providing a scientific basis for BBR to improve sepsis and a new direction for the study of the biological mechanism.

Probiotics protect against hepatic steatosis in tris (2-chloroethyl) phosphate-induced metabolic disorder of mice via FXR signaling

Tris (2-chloroethyl) phosphate (TCEP), the most widely useful and most frequently detective organophosphate flame retardants in environment, has been shown potential relationship with adolescent weight. Probiotics is an effective therapy for metabolic diseases such as obesity and NAFLD with gut microbiota dysregulation. This study aims to explore the protective effects of probiotics against lipid metabolic disorder induced by chronic TCEP exposure and demonstrate the mechanism of this event. The data showed that dietary complex probiotics supplement attenuated TCEP-induced obesity, hyperlipidemia, liver dysfunction, and hepatic steatosis. In addition, dietary complex probiotics suppressed TCEP-promoted ileal FXR signaling, and upregulated hepatic FXR/SHP pathway inhibited by TCEP. Moreover, dietary complex probiotics stimulated PPARα-mediated lipid oxidation and suppressed SREBP1c/PPARγ-mediated lipid synthesis via regulation of FXR signaling. Therefore, this study indicates that dietary complex probiotics could protect against hepatic steatosis via FXR-mediated signaling pathway in TCEP-induced metabolism disorder in mice, resulting in attenuation of systemic lipid accumulation.

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.

Risk factors for the prognosis of patients with sepsis in intensive care units

Background and purpose

To date, sepsis remains the main cause of mortality in intensive care units (ICU). This study aimed analyze the risk factors of the prognosis in sepsis patients.

Methods

In this case-control study, patients with sepsis admitted to the intensive care unit of a Chinese hospital between January and November 2020 were analyzed. Ultrasound and clinical data were analyzed and compared between non-survivors and survivors. The ROC curve analysis was also performed to determine the best indicator for predicting mortality.

Results

A total of 72 patients with sepsis in ICU were included for analysis. The basic characteristics between the survivals and non-survivals were similar, except for acute physiology and chronic health evaluation (APACHE) Ⅱ score, sepsis-related organ failure assessment (SOFA) score, lactate level, ultrasound parameters from superior mesenteric artery (SMA) such as peak systolic velocity (PSV), end-diastolic velocity (EDV) and resistive index (RI). Univariate analysis revealed that the APACHE Ⅱ score, SOFA score, lactate, low PSV, EDV, and RI were potential risk factors for mortality in sepsis, while multivariate analysis suggested that low PSV was an independent risk factor for mortality, and the adjusted odds ratio was 0.295 (95% CI: 0.094–0.925). The ROC analysis showed that the PSV (AUC = 0.99; sensitivity and specificity were 0.99 and 0.96, respectively) had good predictive value for mortality in sepsis.

Conclusion

Low PSV as found to be an independent risk factor and good predictor for mortality in patients with sepsis. This study shows the promise of ultrasound in predicting mortality in patients with sepsis; however, further studies are needed to validate these results.

Critical roles of sepsis-reshaped fecal virota in attenuating sepsis severity

Because studies on all fecal organisms (bacteria, fungi, and viruses) in sepsis are rare and bacteriophages during sepsis might have adapted against gut bacteria with possible pathogenicity, cecal ligation and puncture (CLP; a sepsis mouse model) was evaluated. In fecal bacteriome, sepsis increased Bacteroides and Proteobacteria but decreased Firmicutes, while fecal virome demonstrated increased Podoviridae when compared with sham feces. There was no difference in the fungal microbiome (predominant Ascomycota in both sham and CLP mice) and the abundance of all organisms between sepsis and control groups. Interestingly, the transfers of feces from CLP mice worsened sepsis severity when compared with sham fecal transplantation, as evaluated by mortality, renal injury (serum creatinine and histology), liver damage (liver enzyme and histology), spleen apoptosis, serum cytokines, endotoxemia, and bacteremia. In contrast, the transfers of fecal viral particles from sepsis mice, but not from sham mice, attenuated inflammation in CLP sepsis possibly through the decrease in several fecal pathogenic bacteria (such as Proteobacteria, Gammaproteobacteria, and Prevotellaceae) as evaluated by fecal microbiome analysis. Perhaps the isolation of favorable bacteriophages in sepsis feces and increased abundance ex vivo before oral treatment in a high concentration are beneficial.

Pathophysiology in patients with polytrauma

The pathophysiology after polytrauma represents a complex network of interactions. While it was thought for a long time that the direct and indirect effects of hypoperfusion are most relevant due to the endothelial permeability changes, it was discovered that the innate immune response to trauma is equally important in modifying the organ response. Recent multi center studies provided a "genetic storm" theory, according to which certain neutrophil changes are activated at the time of injury. However, a second hit phenomenon can be induced by activation of certain molecules by direct organ injury, or pathogens (damage associated molecular patterns, DAMPS - pathogen associated molecular patterns, PAMPS). The interactions between the four pathogenetic cycles (of shock, coagulopathy, temperature loss and soft tissue injuries) and cross-talk between coagulation and inflammation have also been identified as important modifiers of the clinical status. In a similar fashion, overzealous surgeries and their associated soft tissue injury and blood loss can induce secondary worsening of the patient condition. Therefore, staged surgeries in certain indications represent an important alternative, to allow for performing a "safe definitive surgery" strategy for major fractures. The current review summarizes all these situations in a detailed fashion.

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.

Roles and Molecular Mechanisms of Physical Exercise in Sepsis Treatment

Physical exercise is a planned, purposeful action to keep a healthy lifestyle and improve physical fitness. Physical exercise has been widely used as a non-pharmacological approach to preventing and improving a wide range of diseases, including cardiovascular disease, cancer, metabolic disease, and neurodegenerative disease. However, the effects of physical exercise on sepsis have not been summarized until now. In this review, we discuss the effects of physical exercise on multiple organ functions and the short- and long-time outcomes of sepsis. Furthermore, the molecular mechanisms underlying the protective effects of physical exercise on sepsis are discussed. In conclusion, we consider that physical exercise may be a beneficial and non-pharmacological alternative for the treatment of sepsis.

Alterations of the Gut Microbiome in Chinese Zhuang Ethnic Patients with Sepsis

Objectives

Sepsis is characterized as a dysregulated host immune response to infection and has been known to be closely associated with the gut microbiome. This study was aimed at investigating the gut microbial profiles of Zhuang ethnic patients with sepsis.

Method

Eleven Zhuang ethnic patients with sepsis and 20 healthy individuals (controls) were recruited at the Baise City People's Hospital, China. Their gut microbial community profiles were analyzed by 16S rRNA gene sequencing using the Illumina MiSeq system.

Results

The gut microbial community of patients with sepsis was significantly altered compared to that of the healthy individuals based on the results of principal coordinate analysis and microbial ecological networks. Additionally, significantly lower microbial alpha diversity was observed in patients with sepsis than in healthy individuals. In particular, the enrichment of Bilophila, Burkholderia, Corynebacterium, and Porphyromonas, along with the reduced abundance of a large number of short-chain fatty acid-producing microbes, including Roseburia, Bifidobacterium, Faecalibacterium, Coprococcus, Blautia, Clostridium, Ruminococcus, and Anaerostipe was observed in patients with sepsis compared to the control group. Moreover, patients with sepsis could be effectively classified based on the abundance of these bacteria using a support vector machine algorithm.

Conclusion

This study demonstrated significant differences in the gut microbiome between Zhuang ethnic patients with sepsis and healthy individuals. In the future, it is necessary to determine whether such alterations are the cause or consequence of sepsis.

Sepsis-Induced Gut Dysbiosis Mediates the Susceptibility to Sepsis-Associated Encephalopathy in Mice

Sepsis-associated encephalopathy (SAE) is common in septic patients and is associated with adverse outcomes. The gut microbiota has been recognized as a key mediator of neurological disease development. However, the exact role of the gut microbiota in regulating SAE remains elusive. Here, we investigated the role of the gut microbiota in SAE and its underlying mechanisms. Cecal ligation and puncture (CLP) was conducted to induce sepsis in mice. Neurological scores were recorded to distinguish SAE-resistant (SER) (score of >6 at 36 h postoperatively) from SAE-susceptible (SES) (score of ≤6 at 36 h postoperatively) mice. 16S rRNA gene sequencing and metabolomics analyses were used to characterize the gut microbiota in the two groups. Fecal microbiota transplantation was performed to validate the role of the gut microbiota in SAE progression. The gut microbiota was more severely disrupted in SES mice than in SER mice after sepsis modeling. Interestingly, mice receiving postoperative feces from SES mice exhibited more severe cortical inflammation than mice receiving feces from SER mice. Indole-3-propionic acid (IPA), a neuroprotective molecule, was more enriched in feces from SER mice than in feces from SES mice. IPA alleviated CLP-induced anxiety and spatial memory impairment in septic mice. Moreover, IPA markedly inhibited NLRP3 inflammasome activation and interleukin-1β (IL-1β) secretion in lipopolysaccharide-stimulated microglia. These responses were attenuated after antagonizing the aryl hydrocarbon receptor. Our study indicates that the variability in sepsis-induced gut dysbiosis mediates the differential susceptibility to SAE in CLP-induced experimental sepsis mice, and microbially derived IPA is possibly involved in SAE development as a neuroprotective compound.

IMPORTANCE The bidirectional interactions between the gut microbiota and sepsis-associated encephalopathy (SAE) are not well characterized. We found that the gut microbiota was more severely disturbed in SAE-susceptible (SES) mice than in SAE-resistant (SER) mice after sepsis modeling. Mice gavaged with postoperative feces from SES mice exhibited more severe neuroinflammation than mice gavaged with feces from SER mice. The gut microbiota from SER mice enriched a neuroprotective metabolite, IPA, which appeared to protect mice from SAE. The potential underlying mechanism of the protective effect of IPA may be mediated via the inhibition of NLRP3 inflammasome activation and IL-1β secretion in microglia. These anti-inflammatory effects of IPA may be regulated by aryl hydrocarbon receptors. These results enhance our understanding of the role of the intestinal microbiota in sepsis. In particular, gut microbiota-derived IPA may serve as a potential therapeutic agent to prevent neuroinflammation in SAE.

Emodin Ameliorates Intestinal Dysfunction by Maintaining Intestinal Barrier Integrity and Modulating the Microbiota in Septic Mice

Sepsis-induced inflammatory response leads to intestinal damage and secondary bacterial translocation, causing systemic infections and eventually death. Emodin is a natural anthraquinone derivative in many plants with promising bioactivities. However, the effects and mechanisms of emodin on sepsis-induced intestinal dysfunctions have not been well clarified yet. We found that emodin treatment suppressed the inflammatory response in the intestines of septic mice. Intestinal barrier function was also improved by emodin through enhancing ZO-1 and occludin expression, which prevented the secondary translocation of Escherichia coli. By proteome microarray investigation, JNK2 was identified as a direct target of emodin. In vitro study also showed that emodin inhibited LPS-induced inflammatory response in intestinal epithelial cells. Nuclear factors including NF-κB and AP-1 were further identified as downstream effectors of JNK2. Bioinformatic analysis based on 16s rRNA gene sequencing illustrated that emodin treatment significantly increased the alpha- and beta-diversity of gut microbiota in septic mice. Moreover, data according to functional prediction showed that emodin decreased the abundance of potential pathogenic bacteria in gut. Our findings have shown that emodin treatment prevented inflammatory induced barrier dysfunction and decreased the potential pathogenicity of lumen bacteria, reducing the hazard of lumen bacterial translocation during sepsis.

Interaction Between Altered Gut Microbiota and Sepsis: A Hypothesis or an Authentic Fact?

Sepsis, as an important public health concern, is one of the leading causes of death in hospitals around the world, accounting for 25% of all deaths. Nowadays, several factors contribute to the development of sepsis. The role of the gut microbiota and the response state of the aberrant immune system is dominant. The effect of the human microbiome on health is undeniable, and gut microbiota is even considered a body organ. It is now clear that the alteration in the normal balance of the microbiota (dysbiosis) is associated with a change in the status of immune system responses. Owing to the strong association between the gut microbiota and its metabolites particularly short-chain fatty acids with many illnesses, the gut microbiota has a unique position in the research of microbiologists and even clinicians. This review aimed to analyze studies’ results on the association between microbiota and sepsis, with a substantial understanding of their relationship. As a result, an extensive and comprehensive search was conducted on this issue in existing databases.

The role of bacterial translocation in sepsis: a new target for therapy

Sepsis is a leading cause of death in critically ill patients, primarily due to multiple organ failures. It is associated with a systemic inflammatory response that plays a role in the pathogenesis of the disease. Intestinal barrier dysfunction and bacterial translocation (BT) play pivotal roles in the pathogenesis of sepsis and associated organ failure. In this review, we describe recent advances in understanding the mechanisms by which the gut microbiome and BT contribute to the pathogenesis of sepsis. We also discuss several potential treatment modalities that target the microbiome as therapeutic tools for patients with sepsis.

Tetrastigma hemsleyanum Diels et Gilg ameliorates lipopolysaccharide induced sepsis via repairing the intestinal mucosal barrier

OBJECTIVE

Sepsis causes excessive systemic inflammation and leads to multiple organ dysfunction syndrome (MODS). The intestine plays a key role in the occurrence and development of sepsis. Tetrastigma hemsleyanum Diels et Gilg (San ye qing, SYQ), a precious Chinese medicine, has been widely used for centuries due to its high traditional value, such as a remarkable anti-inflammatory effect. However, the role of SYQ in intestinal permeability during the development of sepsis needs to be discovered.

METHODS

Mice were intraperitoneally injected with lipopolysaccharide (LPS) to simulate intestinal mucosal barrier function damage in sepsis. Pathological section, inflammatory cytokines, tight junctions, cell apoptosis, and intestinal flora were detected to evaluate the protective effect of SYQ on intestinal mucosal barrier injury in LPS-induced septic mice.

RESULTS

The results showed that SYQ treatment obviously attenuated LPS-induced intestinal injury and reduced the production of tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), and interleukin 6 (IL-6). Besides, SYQ also up-regulated the expressions of tight junctions, including Zonula occludens 1 (ZO-1), Claudin-5, and Occludin along with a decreased in the levels of myosin light chain kinase (MLCK) and myosin light chain (MLC). In addition, SYQ down-regulated the expression of Bax/Bcl2 as well as that of cleaved caspase-3 to prevent the cells from undergoing apoptosis. Further, SYQ restored the diversity of the intestinal flora, increased the abundance of Firmicutes, and decreased the abundance of Bacteroidota.

CONCLUSIONS

The study indicated that SYQ exerted its protective effect on intestinal mucosal barrier injury in LPS-induced septic mice by reducing inflammatory response, improving the tight junction protein expression, inhibiting cell apoptosis, and adjusting the intestinal flora structure.

The liver-gut-axis: initiator and responder to sepsis

PURPOSE OF REVIEW

The 'gut-liver axis' is thought to play an important role in pathogenesis of sepsis. Despite a wealth of experimental data to support the concept of reciprocal crosstalk between gut and liver through bacterial translocation and shaping of the microbiome by liver-derived molecules, for example bile acids, clinical data, and in particular diagnostic and therapeutic options, are limited.

RECENT FINDINGS

Assessment of organ failure in the current definition of sepsis is operationalized by means of the Sequential Organ Failure Assessment (SOFA) score, including exclusively bilirubin to reflect the complex functions of the liver but ignoring the gut. However, our understanding of the intestinal microbiome and how it is affected by critical illness has clearly improved. Microbiota maintain gut-barrier function and modulate the innate and adaptive immune system. The best-defined intervention affecting the gut microbiome, that is selective decontamination of the digestive tract (SDD) is clinically studied regarding prevention of nosocomial lung infection and antibiotic resistance patterns, although its impact on liver function has not been systematically evaluated in critical illness.

SUMMARY

Characterization of liver function beyond bilirubin and the microbiome can be achieved with contemporary sequencing and metabolomic techniques. Such studies are essential to understand how gut-liver crosstalk and 'dysbiosis' affect susceptibility to and outcome of sepsis.

Metformin attenuated sepsis-related liver injury by modulating gut microbiota

Increased evidence shows that gut microbiota acts as the primary regulator of the liver; however, its role in sepsis-related liver injury (SLI) in the elderly is unclear. This study assessed whether metformin could attenuate SLI by modulating gut microbiota in septic-aged rats. Cecal ligation and puncture (CLP) was used to induce SLI in aged rats. Fecal microbiota transplantation (FMT) was used to validate the roles of gut microbiota in these pathologies. The composition of gut microbiota was analysed by 16S rRNA sequencing. Moreover, the liver and colon tissues were analysed by histopathology, immunofluorescence, immunohistochemistry, and reverse transcription polymerase chain reaction (RT–PCR). Metformin improved liver damage, colon barrier dysfunction in aged SLI rats. Moreover, metformin improved sepsis-induced liver inflammation and damage under gut microbiota. Importantly, FMT assay showed that rats gavaged with faeces from metformin-treated SLI rats displayed less severe liver damage and colon barrier dysfunctions than those gavaged with faeces from SLI rats. The gut microbiota composition among the sham-operated, CLP-operated and metformin-treated SLI rats was different. In particular, the proportion of Klebsiella and Escherichia_Shigella was higher in SLI rats than sham-operated and metformin-treated SLI rats; while metformin could increase the proportion of Bifidobacterium, Muribaculaceae, Parabacteroides_distasonis and Alloprevitella in aged SLI rats. Additionally, Klebsiella and Escherichia_Shigella correlated positively with the inflammatory factors in the liver. Our findings suggest that metformin may improve liver injury by regulating the gut microbiota and alleviating colon barrier dysfunction in septic-aged rats, which may be an effective therapy for SLI.

Fecal Microbiota Analysis in Cats with Intestinal Dysbiosis of Varying Severity

Recent studies have shown that the gut microbiota plays an important role in the pathogenesis of gastrointestinal diseases in various animal species. There are only limited data on the microbiome in cats with varying grades of dysbiosis. The purpose of the study was a detailed analysis of the quantitative and qualitative fecal microbiota spectrum in cats with intestinal dysbiosis of varying severity. The data obtained indicate that, depending on the dysbiosis severity in cats, the intestinal microbiome landscape changes significantly. It has been established that, depending on the dysbiosis severity, there is a shift in the balance between the Gram-positive and Gram-negative bacterial pools and in the nature of the isolation of specific bacteria forms, in the amount of obligate microbiota isolation, as well as individual facultative strains. When analyzing the serotyping of E. coli cultures isolated at various grades of intestinal dysbiosis severity, differences were found both in the isolation amount of various serotypes from one animal and in the prevalence of certain serotypes for each disease severity. A retrospective analysis of the fecal microbiota sensitivity in cats with dysbiosis to antibacterial drugs showed that, depending on the disease severity, the number of isolates sensitive to antibiotics increases significantly.

Insights into the Ancient Adaptation to Intertidal Environments by Red Algae Based on a Genomic and Multiomics Investigation of Neoporphyra haitanensis

Colonization of land from marine environments was a major transition for biological life on Earth, and intertidal adaptation was a key evolutionary event in the transition from marine- to land-based lifestyles. Multicellular intertidal red algae exhibit the earliest, systematic, and successful adaptation to intertidal environments, with Porphyra sensu lato (Bangiales, Rhodophyta) being a typical example. Here, a chromosome-level 49.67 Mb genome for Neoporphyra haitanensis comprising 9,496 gene loci is described based on metagenome-Hi-C-assisted whole-genome assembly, which allowed the isolation of epiphytic bacterial genome sequences from a seaweed genome for the first time. The compact, function-rich N. haitanensis genome revealed that ancestral lineages of red algae share common horizontal gene transfer events and close relationships with epiphytic bacterial populations. Specifically, the ancestor of N. haitanensis obtained unique lipoxygenase family genes from bacteria for complex chemical defense, carbonic anhydrases for survival in shell-borne conchocelis lifestyle stages, and numerous genes involved in stress tolerance. Combined proteomic, transcriptomic, and metabolomic analyses revealed complex regulation of rapid responses to intertidal dehydration/rehydration cycling within N. haitanensis. These adaptations include rapid regulation of its photosynthetic system, a readily available capacity to utilize ribosomal stores, increased methylation activity to rapidly synthesize proteins, and a strong anti-oxidation system to dissipate excess redox energy upon exposure to air. These novel insights into the unique adaptations of red algae to intertidal lifestyles inform our understanding of adaptations to intertidal ecosystems and the unique evolutionary steps required for intertidal colonization by biological life.

Characterization and predictive functional profiles on metagenomic 16S rRNA data of liver transplant recipients: A longitudinal study

Long-term survival after Liver Transplantation (LT) is often compromised by infectious and metabolic complications. We aimed to delineate alterations in intestinal microbiome (IM) over time that could contribute to medical complications compromising long-term survival following LT. Fecal samples from LT recipients were collected at 3 months (3 M) and 6 months (6 M) post-LT. The bacterial DNA was extracted using E.Z.N.A. Stool DNA Kit and 16S rRNA gene sequencing at V4 hypervariable region was performed. DADA2 and Phyloseq was implemented to analyze the taxonomic composition. Differentially abundant taxa were identified by metagenomeSeq and LEfSe. Piphillin, an Inferred functional metagenomic analysis tool was used to study the bacterial functional content. For comparison, healthy samples were extracted from NCBI and analyzed similarly. The taxonomic & functional profiles of LT recipients were validated with metagenomic sequencing data from animals exposed to immunosuppressants using Venny. Our findings provide a new perspective on longitudinal increase in specific IM communities post-LT along with an increase in bacterial genes associated with metabolic and infectious disease.

Crosstalk between gut microbiota and sepsis

Sepsis is an overwhelming inflammatory response to microbial infection. Sepsis management remains a clinical challenge. The role of the gut microbiome in sepsis has gained some attention. Recent evidence has demonstrated that gut microbiota regulate host physiological homeostasis mediators, including the immune system, gut barrier function and disease susceptibility pathways. Therefore, maintenance or restoration of microbiota and metabolite composition might be a therapeutic or prophylactic target against critical illness. Fecal microbiota transplantation and supplementation of probiotics are microbiota-based treatment methods that are somewhat limited in terms of evidence-based efficacy. This review focuses on the importance of the crosstalk between the gastrointestinal ecosystem and sepsis to highlight novel microbiota-targeted therapies to improve the outcomes of sepsis treatment.

Kombucha ameliorates LPS-induced sepsis in a mouse model

As a popular traditional fermented beverage, kombucha has been extensively studied for its health benefits. However, the science behind the anti-inflammatory effect of kombucha has not been well studied, and there is an urgent need to uncover the secrets of the anti-inflammatory properties of kombucha. Here, we investigate kombucha's protective effects against lipopolysaccharide (LPS)-induced sepsis and on the intestinal microecology in mice. The contents of reducing sugars, polyphenols, catechins, and organic acids in the kombucha group were identified using various methods. The results showed that the concentrations of acetic acid, gluconic acid, polyphenol, and glucuronic acid in the kombucha group were 55.70 ± 2.57 g L^-1, 50.20 ± 1.92 g L^-1, 2.36 ± 0.31, and 1.39 ± 0.22 g L^-1, respectively. The result also demonstrated that kombucha effectively improves the survival rate from 0% to 40%, and increases the thermoregulation in LPS-treated mice, which showed decreased mobility and had lost their appetite for food. Furthermore, kombucha reduced the levels of tumor necrosis factor-α and interleukins (IL)-1β and IL-6, restored the levels of T cells and macrophages in LPS-challenged mice, alleviated the histopathological damage, and inhibited NF-κB signaling in mice with LPS-induced sepsis. We demonstrated that kombucha effectively prevents cellular immune function disorder in mice at the initial stage of sepsis and exerts an immunomodulatory effect. In addition, the effect of kombucha on the gut microbiota was investigated during sepsis. Kombucha supplementation altered the diversity of the gut microbiota and promoted the growth of butyrate-producing bacteria, which exert anti-inflammatory effects. Our results illustrate the potential of kombucha as a novel anti-inflammatory agent against the development of systemic inflammatory responses associated with sepsis.

Fecal Microbiota Transplantation Protects the Intestinal Mucosal Barrier by Reconstructing the Gut Microbiota in a Murine Model of Sepsis

The gastrointestinal (GI) tract has long been hypothesized to play an integral role in the pathophysiology of sepsis, and gut microbiota (GM) dysbiosis may be the key factor. Previous studies have shown that the gut flora was significantly altered in critically ill patients. This study aimed to observe what kind of GM dysbiosis is in the early stage of sepsis and whether the application of fecal microbiota transplantation (FMT) can reconstruct the GM of septic mice and restore its protective function on the intestinal mucosal barrier. The study investigated the effect of FMT on gut microbiota, mucosal barrier function, inflammatory response, and survival in a murine model of sepsis established by cecal ligation and puncture (CLP). It is found that FMT can not only reduce morbidity and mortality and restore the abundance and diversity of the gut flora in septic mice, but can also improve the intestinal barrier function by reducing epithelial cell apoptosis, improving the composition of the mucus layer, upregulating the expression of tight junction proteins, and reducing intestinal permeability and the inflammatory response. After FMT, Lachnospiraceae contributed the most to intestinal protection through enhancement of the L-lysine fermentation pathway. FMT offers a microbe-mediated survival advantage in a murine model of sepsis. Therefore, an improved understanding of the connection between microbiota, and systemic illness may yield new therapeutic strategies for patients with sepsis.

Biomimetic microcavity interfaces for a label-free capture of pathogens in the fluid bloodstream by vortical crossflow filtration

Bacterial sepsis is a lethal disease triggered by microbial pathogens. The blood pathogen load is a major contributor to both disease severity and mortality in patients with sepsis blood. Therefore, it is crucial to reduce the load of pathogens, in particular the drug-resistant pathogens. In this work, inspired by the crossflow filtration mechanism in suspension-feeding fish, we developed a biomimetic microcavity interface to mimic a porous gill-raker surface as a blood-cleansing dialyzer for sepsis therapy, which can rapidly, safely and efficiently clear bacteria from the fluidic blood. The microcavity interface consists of microcavity arrays, the innerface of which contains nanowire forests. By precisely controlling the pore size of the microcavity and directing the axial travel of the fluid, the bacteria can be isolated from the whole blood without disturbing any blood components or blocking the blood cell transportation. In addition, the three-dimensional nanowire forests assist in the formation of vortices with reduced blood flow velocity and increased resistance to bacterial deposition in situ. Functional modification is not required to recognize the bacteria specifically in our designed dialyzer. Moreover, the microcavity interface clears over 95% bacteria from a fluid blood sample without inducing protein adsorption or complement and platelet activation when contacting the fluid blood. The study supports this biomimetic microcavity interface to be a promising extracorporeal blood-cleansing device in clinical settings.

Gut Microbial Changes and their Contribution to Post-Burn Pathology

ABSTRACT

Burn injuries are a common form of traumatic injury that leads to significant morbidity and mortality worldwide. Burn injuries are characterized by inflammatory processes and alterations in numerous organ systems and functions. Recently, it has become apparent that the gastrointestinal bacterial microbiome is a key component of regulating the immune response and recovery from burn and can also contribute to significant detrimental sequelae after injury, such as sepsis and multiple organ failure. Microbial dysbiosis has been linked to multiple disease states; however, its role in exacerbating acute traumatic injuries, such as burn, is poorly understood. In this article, we review studies that document changes in the intestinal microbiome after burn injury, assess the implications in post-burn pathogenesis, and the potential for further discovery and research.

Probiotics for the Management of Sepsis: Advances in Animal Models and Intensive Care Unit Environments

Sepsis frequently leads to multiple organ failure and is a major cause of morbidity and mortality in critically ill patients. Although intensive care protocols and antibiotic therapy have improved sepsis treatment, specific management is lacking with respect to efficient protection from tissue damage and long-term outcomes. Probiotics are live microbes that modulate the immune system and inflammation and colonize the gut. In this narrative review, we have traced the evolution of the administration of probiotics in an animal model of sepsis and treatment alternatives in the intensive care unit setting. First, probiotics are categorized by species before describing their modulation of the microbiota, repair of tissue-specific damage, immune response, and molecular pathways to prevent complications. The impact on therapy for infant and adult patients is also addressed. Finally, we have emphasized the challenges and gaps in current studies as well as future perspectives for further investigation. The present review can open up avenues for new strategies that employ promising probiotic strains for the treatment of sepsis and discusses their ability to prevent disease-associated long-term complications.

Nutritional Status and the Critically Ill Patient: Gut Microbiota and Immuno-Nutrition in I.C.U. at the Time of SARS-COV 2 Pandemic

Background: Gut microbiota is a complex ecosystem of bacteria, viruses, archaea, protozoa and yeasts in our intestine. It has several functions, including maintaining human body equilibrium. Microbial “dysbiosis” can be responsible for outbreak of local and systemic infections, especially in critically ill patients. Methods: to build a narrative review, we performed a Pubmed, Medline and EMBASE search for English language papers, reviews, meta-analyses, case series and randomized controlled trials (RCTs) by keywords and their associations: critically ill patient; nutrition; gut microbiota; probiotics; gut virome; SARS-COV 2. Results: Over the antibiotic-based “selective decontamination”, potentially responsible for drug-resistant microorganisms development, there is growing interest of scientists and the pharmaceutical industry for pre-, probiotics and their associations as safe and reliable remedies restoring gut microbial “eubiosis”. Very first encouraging evidences link different gut microbiota profiles with SARS-COV 2 disease stage and gravity. Thus, there is frame for a probiotic therapeutic approach of COVID-19. Conclusions: gut microbiota remodulation seems to be a promising and safe therapeutic approach to prevent local and systemic multi-resistant bug infections in the intensive care unit (ICU) patients. This approach deserves more and more attention at the time of SARS-COV 2 pandemic.