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

Interaction Between Gut-Heart Axis in Sepsis-Induced Cardiomyopathy

The gut microbiota and its metabolites profoundly influence cardiac function, emerging as critical players in the pathophysiology of Sepsis-Induced Cardiomyopathy (SIC). Conversely, therapeutic interventions for SIC and the resultant cardiac alterations can reciprocally modulate gut microbial composition and function. To systematically elucidate this complex bidirectional relationship during SIC, this review delineates two key aspects: the 'forward gut-heart axis', defined as influences originating from the gut microbiota and its metabolites directed towards the cardiovascular system, and the 'reverse gut-heart axis', encompassing the reciprocal effects of cardiovascular drugs and cardiac factors on the gut microbiota. Furthermore, we explore potential therapeutic strategies for SIC centered on the targeted modulation of this intricate gut-heart interplay.

Pseudomonas aeruginosa population dynamics in a vancomycin-induced murine model of gastrointestinal carriage

Pseudomonas aeruginosa is a common nosocomial pathogen and a major cause of morbidity and mortality in hospitalized patients. Multiple reports highlight that P. aeruginosa gastrointestinal colonization may precede systemic infections by this pathogen. Gaining a deeper insight into the dynamics of P. aeruginosa gastrointestinal carriage is an essential step in managing gastrointestinal colonization and could contribute to preventing bacterial transmission and progression to systemic infection. Here, we present a clinically relevant mouse model relying on parenteral vancomycin pretreatment and a single orogastric gavage of a controlled dose of P. aeruginosa. Robust carriage was observed with multiple clinical isolates, and carriage persisted for up to 60 days. Histological and microbiological examination of mice indicated that this model indeed represented carriage and not infection. We then used a barcoded P. aeruginosa library along with the sequence tag-based analysis of microbial populations (STAMPR) analytic pipeline to quantify bacterial population dynamics and bottlenecks during the establishment of the gastrointestinal carriage. Analysis indicated that most of the P. aeruginosa population was rapidly eliminated in the stomach, but the few bacteria that moved to the small intestine and the cecum expanded rapidly. Hence, the stomach constitutes a significant barrier against gastrointestinal carriage of P. aeruginosa, which may have clinical implications for hospitalized patients.

IMPORTANCE

While Pseudomonas aeruginosa is rarely part of the normal human microbiome, carriage of the bacterium is quite frequent in hospitalized patients and residents of long-term care facilities. P. aeruginosa carriage is a precursor to infection. Options for treating infections caused by difficult-to-treat P. aeruginosa strains are dwindling, underscoring the urgency to better understand and impede pre-infection stages, such as colonization. Here, we use vancomycin-treated mice to model antibiotic-treated patients who become colonized with P. aeruginosa in their gastrointestinal tracts. We identify the stomach as a major barrier to the establishment of gastrointestinal carriage. These findings suggest that efforts to prevent gastrointestinal colonization should focus not only on judicious use of antibiotics but also on investigation into how the stomach eliminates orally ingested P. aeruginosa.

Desulfovibrio vulgaris exacerbates sepsis by inducing inflammation and oxidative stress in multiple organs

Introduction

Sepsis is a life-threatening condition that often leads to organ dysfunction and systemic inflammation, with gut microbiota dysbiosis playing a crucial role in its pathogenesis. The role of Desulfovibrio vulgaris (D. vulgaris), a potentially pathogenic bacterium, in sepsis remains unclear.

Methods

We first assessed the abundance of D. vulgaris in the feces of septic mice and patients using qPCR. Mice were then orally gavaged with D. vulgaris (2 × 108 CFU/mouse/day) for 7 consecutive days followed by cecal ligation and puncture (CLP) surgery. We monitored survival, assessed organ damage, and measured inflammation. Peritoneal macrophages were isolated to analyze the phosphorylation of key MAPK and NF-κB signaling pathways. Finally, oxidative stress levels in the liver, lungs, and kidneys were evaluated, measuring markers such as GSH, CAT, and SOD.

Results

The abundance of D. vulgaris was significantly increased in the feces of both septic mice and patients. Supplementation with D. vulgaris exacerbated sepsis in mice, resulting in lower survival rates, more severe organ damage, and heightened inflammation. Phosphorylation of MAPK and NF-κB pathways in peritoneal macrophages was significantly enhanced. Additionally, D. vulgaris amplified oxidative stress across multiple organs, as indicated by increased ROS levels and decreased antioxidant enzyme activity.

Conclusion

Our findings suggest that D. vulgaris exacerbates the progression of sepsis by enhancing inflammation, activating key immune signaling pathways, and increasing oxidative stress. These processes contribute to organ dysfunction and increased mortality, highlighting the potential pathogenic role of D. vulgaris in sepsis.

Human microbiota in dengue infection: A narrative review

Dengue fever, a widespread mosquito-borne viral infection in tropical regions, typically manifests fever and gastrointestinal symptoms, including nausea, vomiting, and diarrhea. However, the human gut microbiota's role in dengue pathogenesis remains incompletely understood. Studies have demonstrated dysbiosis during dengue virus infection, characterized by increased abundance of potentially pathogenic bacteria like Bacteroidaceae and Proteobacteria, particularly during the critical phase. Furthermore, microbial translocation and leaky gut syndrome, characterized by the translocation of intestinal microbial products, have been observed in dengue patients and are associated with hypercytokinemia, plasma leakage, and disease severity. These findings underscore the necessity for an in-depth investigation into the role of human intestinal microbiota as a potential contributing factor in the pathogenesis and progression of dengue. Further research focusing on human intestinal microbiota, leaky gut syndrome, and the potential implications of treatment with oral bacteriotherapy, as previously observed in other viral diseases, is essential to clarify dengue pathology and evaluate new therapeutic strategies.

Alcohol-induced gut permeability defect through dysbiosis and enterocytic mitochondrial interference causing pro-inflammatory macrophages in a dose dependent manner

Although toxicity of alcohol toward the intestines and immunity is mentioned, there might be different effect of alcohol in a low and a high dose and the rodent model development using a simple SHIRPA binary score night be useful. Hence, a low and high dose of alcohol (6.30 and 1.26 g/kg/day) were administered in might for 16 weeks before determination of several parameters. As such, the peak blood alcohol concentration (BAC) of low and high dose of alcohol were approximately at 0.05 and 0.15%, respectively, at 1 h post-administration, which correlated with SHIRPA score at 1.8 ± 0.8 and 7.2 ± 0.6, respectively. After 16 wk of administration, a significant liver injury in high-dose alcohol was indicated by liver enzymes, liver weight, histology score, apoptosis, and hepatic accumulation of triglyceride (TG) and oxidative stress (malondialdehyde; MDA) with reduced anti-oxidant (glutathione). Meanwhile, low-dose alcohol demonstrated only elevated apoptosis with increased TG and MDA in liver tissue. Leaky gut from both dose of alcohol was also demonstrated by FITC-dextran, endotoxemia, serum beta glucan, and reduced occludin. However, bacterial abundance (microbiome analysis) of the feces from small bowel of high-dose alcohol, but not the low dose, was different from the control (increased Alitipes spp. with reduced Lachnospiraceae). In conclusion, both low- and high-dose alcohol induced leaky gut, while only the high-dose caused gut dysbiosis and alcohol damaged mitochondria but enhanced glycolysis in enterocytes and macrophages. Leaky gut might be more sensitive than dysbiosis to determine alcohol-induced intestinal injury.

Accelerating and protective effects toward cancer growth in cGAS and FcgRIIb deficient mice, respectively, an impact of macrophage polarization

BACKGROUND

Due to the possible influence of inflammation and gut microbiota in cancers.

METHODS

Fc gamma receptor IIb deficient (FcGRIIb-/-) and cyclic GMP-AMP synthase deficient (cGAS-/-) mice, the model with hyperinflammation and hypo-inflammation, respectively, were subcutaneously injected with MC38 cells (a murine colon cancer cell line).

RESULTS

As such, the tumor burdens were most prominent in cGAS-/- mice, while FcGRIIb-/- mice demonstrated the least tumor sizes compared with wild-type (WT). Intra-tumoral mononuclear cells of FcGRIIb-/- (hematoxylin and eosin staining) were more prominent than other groups with the most dominant CD86-positive cells (mostly M1 proinflammatory macrophages) and the least CD206-positive cells (mostly M2 anti-inflammatory macrophages). While fecal microbiome analysis demonstrated a subtle difference among mouse strains with tumors at 24 days post-cancer injection, serum cytokines (TNF-α, IL-6, IL-1α, IFN-β, IFN-γ, IL-23, IL-12p70, GM-CSF, IL-27, and IL-17A) (fluorescence-encoded bead multiplex assay) and the expansion of immune cells in the spleens of FcGRIIb-/- mice (flow cytometry) were more prominent than others. With bone marrow-derived macrophages, prominent M1 (LPS) and M2 polarization (IL4 and cancer supernatant) in FcGRIIb-/- and cGAS-/- macrophages, respectively, were demonstrated using polymerase chain reaction and flow cytometry. The most prominent tumoricidal activity (percentage of F4/80-negative flexible780 viable dye-positive cells using flow cytometry) of LPS-stimulated FcGRIIb-/- macrophages compared with other groups supported dominant pro-inflammatory characteristics of FcGRIIb-/- macrophages.

CONCLUSIONS

In conclusion, the protective and promoting effects of FcGRIIb-/- and cGAS-/- mice, respectively, against cancers are partly related to macrophage functions with a subtle correlation to fecal microbiota, and FcGRIIb inhibitors and cGAS enhancers might be helpful for cancer adjuvant treatment.

A Novel Frontier in Gut-Brain Axis Research: The Transplantation of Fecal Microbiota in Neurodegenerative Disorders

The gut-brain axis (GBA) represents a sophisticated bidirectional communication system connecting the central nervous system (CNS) and the gastrointestinal (GI) tract. This interplay occurs primarily through neuronal, immune, and metabolic pathways. Dysbiosis in gut microbiota has been associated with multiple neurodegenerative diseases, such as Parkinson's disease (PD), Alzheimer's disease (AD), multiple sclerosis (MS), and amyotrophic lateral sclerosis (ALS). In recent years, fecal microbiota transplantation (FMT) has gained attention as an innovative therapeutic approach, aiming to restore microbial balance in the gut while influencing neuroinflammatory and neurodegenerative pathways. This review explores the mechanisms by which FMT impacts the gut-brain axis. Key areas of focus include its ability to reduce neuroinflammation, strengthen gut barrier integrity, regulate neurotransmitter production, and reinstate microbial diversity. Both preclinical and clinical studies indicate that FMT can alleviate motor and cognitive deficits in PD and AD, lower neuroinflammatory markers in MS, and enhance respiratory and neuromuscular functions in ALS. Despite these findings, several challenges remain, including donor selection complexities, uncertainties about long-term safety, and inconsistencies in clinical outcomes. Innovations such as synthetic microbial communities, engineered probiotics, and AI-driven analysis of the microbiome hold the potential to improve the precision and effectiveness of FMT in managing neurodegenerative conditions. Although FMT presents considerable promise as a therapeutic development, its widespread application for neurodegenerative diseases requires thorough validation through well-designed, large-scale clinical trials. It is essential to establish standardized protocols, refine donor selection processes, and deepen our understanding of the molecular mechanisms behind its efficacy.

A review of gut failure as a cause and consequence of critical illness

In critical illness, all elements of gut function are perturbed. Dysbiosis develops as the gut microbial community loses taxonomic diversity and new virulence factors appear. Intestinal permeability increases, allowing for translocation of bacteria and/or bacterial products. Epithelial function is altered at a cellular level and homeostasis of the epithelial monolayer is compromised by increased intestinal epithelial cell death and decreased proliferation. Gut immunity is impaired with simultaneous activation of maladaptive pro- and anti-inflammatory signals leading to both tissue damage and susceptibility to infections. Additionally, splanchnic vasoconstriction leads to decreased blood flow with local ischemic changes. Together, these interrelated elements of gastrointestinal dysfunction drive and then perpetuate multi-organ dysfunction syndrome. Despite the clear importance of maintaining gut homeostasis, there are very few reliable measures of gut function in critical illness. Further, while multiple therapeutic strategies have been proposed, most have not been shown to conclusively demonstrate benefit, and care is still largely supportive. The key role of the gut in critical illness was the subject of the tenth Perioperative Quality Initiative meeting, a conference to summarize the current state of the literature and identify key knowledge gaps for future study. This review is the product of that conference.

Intestinal Microbiota Dysbiosis Role and Bacterial Translocation as a Factor for Septic Risk

The human immune system is closely linked to microbiota such as a complex symbiotic relationship during the coevolution of vertebrates and microorganisms. The transfer of microorganisms from the mother's microbiota to the newborn begins before birth during gestation and is considered the initial phase of the intestinal microbiota (IM). The gut is an important site where microorganisms can establish colonies. The IM contains polymicrobial communities, which show complex interactions with diet and host immunity. The tendency towards dysbiosis of the intestinal microbiota is influenced by local but also extra-intestinal factors such as inflammatory processes, infections, or a septic state that can aggravate it. Pathogens could trigger an immune response, such as proinflammatory responses. In addition, changes in the host immune system also influence the intestinal community and structure with additional translocation of pathogenic and non-pathogenic bacteria. Finally, local intestinal inflammation has been found to be an important factor in the growth of pathogenic microorganisms, particularly in its role in sepsis. The aim of this article is to be able to detect the current knowledge of the mechanisms that can lead to dysbiosis of the intestinal microbiota and that can cause bacterial translocation with a risk of infection or septic state and vice versa.

Changes in Vitamin D and Gut Microbiota in Pediatric Hematopoietic Stem Cell Transplantation Patients with Bloodstream Infections

BACKGROUND

Vitamin D (VD) and gut microbiota (GM) are important variables in pediatric hematopoietic stem cell transplantation (HSCT) recipients with bloodstream infections (BSI). Both VD and GM play significant roles in immune regulation and in maintaining intestinal barrier function.

METHODS

This prospective case-control study included 48 consecutive pediatric patients who underwent HSCT, as well as 20 healthy children from the community. Plasma samples were collected pre- and post-HSCT, together with post-HSCT fecal samples. Serum 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) were measured using chemiluminescence and enzyme linked immunosorbent assay, respectively. GM was analyzed by 16S rDNA next generation sequencing.

RESULTS

The incidence of BSI in pediatric HSCT recipients was 33.3% (16/48). No significant differences in serum 25(OH)D or 1,25(OH)2D3 levels were observed between the BSI and non-BSI groups either before or after transplantation, or with the healthy control group. The α-diversity of GM in BSI and non-BSI patients was significantly lower than in healthy subjects. Proteobacteria were significantly more abundant in BSI patients than in non-BSI patients (p = 0.0434) or healthy controls (p = 0.0193). Pediatric HSCT patients showed significantly higher levels of Staphylococcus (p < 0.001), Pseudomonas (p < 0.001), Enterococcus (p < 0.001), Clostridium innocuum (p = 0.0175) and Enterobacter (p = 0.0394) compared to the controls, whereas the levels of Firmicutes (p = 0.009), Actinobacteria (p < 0.001), Bifidobacterium (p < 0.001) and Faecalibacterium (p < 0.001) were significantly lower. β-diversity analysis revealed significant population differences between the three groups.

CONCLUSIONS

These results indicate there is no practical value in monitoring VD in HSCT patients. During HSCT and BSI, the GM experiences a loss of probiotics and an increase in potential pathogens.

Gut microbes of the cecum versus the colon drive more severe lethality and multi-organ damage

Intestinal perforations lead to a high risk of sepsis-associated morbidity and multi-organ dysfunctions. A perforation allows intestinal contents (IC) to enter the peritoneal cavity, causing abdominal infections. Right- and left-sided perforations have different prognoses in humans, but the mechanisms associated with different cecum and colon perforations remain unclear. This study investigates how gut flora influences outcomes from perforations at different sites in mice. Using fecal-induced peritonitis mouse model, isolated IC from the cecum or colon was injected peritoneally at 2 mg/kg. Bacterial burden was quantified with quantitative PCR, and microbial communities were analyzed using 16S rRNA gene sequencing. Survival rates were monitored, and blood biochemical indices, histological changes, cytokines expression, immunological signaling and multiple-organ damage were assessed at 16 h post-injections. The results showed cecum IC developed more severe sepsis than colon IC, with shorter median survival time and greater multi-organ damage. Mice treated with cecum IC displayed elevated tissue damage markers in the liver, heart, and kidneys, contributing to worsened pathology. This was likely driven by systematic inflammatory cytokines production and lung inflammation. Mechanistically, cecum IC triggered stronger cGAS-STING and TBK1-NF-κB signaling, promoting systemic inflammation compared to the colon IC. Moreover, bacterial analysis demonstrated that cecum IC carry a higher bacterial burden than colon IC and exhibit a different microbial community. A detailed microbiome comparison revealed an increased abundance of potentially pathogenic bacteria in the cecum IC. These findings suggest that the site of intestinal perforation influences sepsis severity, with the cecum being associated with a higher bacterial burden and a relatively increased abundance of potentially pathogenic bacteria compared to the colon. Our findings first compared the lethality associated with the microbial composition of the cecum and colon, indicating the perforation site could help providers predict the severity of sepsis, thereby introducing a novel perspective to microbiology and sepsis research.

Neurotensin receptor agonist PD149163 modulates LPS-induced enterocyte apoptosis by downregulating TNFR pathway and executioner caspase 3 in endotoxemic mice: insights from in vivo and in silico study

This study was designed to evaluate the dose-dependent efficacy of neurotensin receptor-1 (NTSR1) agonist PD149163 in the amelioration of the lipopolysaccharide (LPS)-induced apoptosis in the gastrointestinal tract (GIT) of mice. PD149163 is an analogue of NTS, a GIT tri-decapeptide with anti-inflammatory and anti-oxidative effects. Swiss-albino mice (female/8 weeks/25 ± 2.5 g) were divided into six groups: control; LPS, LPS + PD149163L, and LPS + PD149163H groups were treated with LPS (0.2 μmol/L/kgBW; 5 days), followed by exposure of PD149163 to LPS + PD149163L (10.6 μmol/L/kgBW), and LPS + PD149163H (21.2 μmol/L/kgBW) for 28 days. OnlyPD149163L (10.6 μmol/L/kgBW) and onlyPD149163H (21.2 μmol/L/kgBW) groups were maintained for 28 days. Both the LPS and PD149163 were given intraperitoneally. PD149163 treatment for 4 weeks alleviated the LPS-induced enterocyte apoptosis in a dose-dependent manner. LPS-induced excessive levels of caspase-3, tumour necrosis factor-α, and leptin (biomarkers of LPS-induced apoptosis) in plasma were decreased by PD149163H treatment. Moreover, LPS-induced gut oxidative stress was ameliorated by PD149163H supplementation, as evidenced by the decreased content of malondialdehyde, lipid-hydroperoxide and increased level of superoxide-dismutase, catalase. Furthermore, PD149163H mediated elevation of the plasma anti-apoptotic protein (B-cell leukaemia/lymphoma-2) along with the NTS level contributed to the modulation of LPS-induced enterocyte apoptosis, reflected in histopathology. In vivo results were substantiated with in silico molecular docking analysis that predicted the binding of PD149163-TLR4 complex, suggesting that PD149163 can act as a TLR4 modulator and inhibit the activation of TLR4. The role of PD149163 in ameliorating GIT apoptosis by its anti-apoptotic and antioxidative effects is suggested. Further research may provide significant insights into the therapeutic intervention of PD149163 in apoptosis-related diseases of GIT.

Effects of Aneurysmal Subarachnoid Hemorrhage in Patients Without In-Hospital Infection on FABP-I, LBP, and sCD-14

Aneurysmal subarachnoid hemorrhage (aSAH) is a serious condition complicated by delayed cerebral ischemia (DCI), where inflammation plays a key role. Although altered gut permeability is noted in other conditions, its significance in aSAH remains unclear. Fatty acid-binding protein (FABP-I), lipopolysaccharide-binding protein (LBP), and soluble CD-14 (sCD-14) are established markers of barrier dysfunction. This study investigates gut permeability marker changes in early and late aSAH phases. The study included 177 aSAH patients and 100 controls. Serum samples were collected on days 1 (D1) and 9 (D9) after ictus. FABP-I, LBP, and sCD-14 levels were measured via ELISA, and clinical data were recorded. Outcomes were assessed using the 90-day modified Rankin scale (mRS 0-3 = favorable outcome). Serum FABP-I was significantly lower in aSAH patients (p < 0.05), while LBP and sCD-14 were higher (p < 0.001) compared to controls. FABP-I did not differ between outcome groups, but LBP and sCD-14 were significantly elevated in unfavorable outcomes (p < 0.001). These markers differed in patients without in-hospital infection, with higher levels noted in DCI patients during the later phase (p < 0.05). In aSAH patients without infection, differences in LBP and sCD-14 levels between outcome groups suggest potential endotoxin release from microbial systems, contributing to neuroinflammation and influencing outcomes.

The intestinal flora: The key to unraveling heterogeneity in immune thrombocytopenia?

Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder characterized by enhanced platelet destruction and impaired platelet production, due to a loss of immune tolerance that leads to targeting of platelets and megakaryocytes by glycoprotein-autoantibodies and/or cytotoxic T cells. There is a high degree of heterogeneity in ITP patients signified by unpredictable disease trajectories and treatment responses. Initial studies in humans have identified intestinal microbiota perturbance in ITP. Recently, gut microbial perturbance has been linked to other autoimmune diseases. Based on these findings, we hypothesize that intestinal microbiota may influence ITP pathophysiology through several mechanisms, including induction of platelet-autoantibody production, increasing complement-dependent platelet cytotoxicity, disturbing T cell homeostasis, impairing megakaryocyte function, and increasing platelet-desialylation and -clearance. The pathophysiological heterogeneity of ITP may, at least in part, be attributed to a perturbed intestinal microbiota. Therefore, a better understanding of intestinal microbiota in ITP may result in a more personalized therapeutic approach.

Functional connectivity within sensorimotor cortical and striatal regions is regulated by sepsis in a sex-dependent manner

Sepsis is a state of systemic immune dysregulation and organ failure that is frequently associated with severe brain disability. Epidemiological studies have indicated that younger females have better prognosis and clinical outcomes relative to males, though the sex-dependent response of the brain to sepsis during post-sepsis recovery remains largely uncharacterized. Using a modified polymicrobial intra-abdominal murine model of surgical sepsis, we characterized the acute effects of intra-abdominal sepsis on peripheral inflammation, brain inflammation and brain functional connectivity in young adult mice of both sexes. Following sepsis, both male and female mice survived the procedure, regained body weight within 7 days post-sepsis and showed reduced diversity in their gut microbiome. Interestingly, compared to the sepsis-induced changes observed in female mice, the post-septic male mice exhibited a comparatively robust profile of splenic cell expansion and intracerebral glial proliferation relative to their healthy counterparts. Analysis of resting-state functional Magnetic Resonance Imaging (fMRI) data collected from the post-septic mice revealed that while connectivity to the somatosensory cortex were affected equally in both sexes, intra-network connectivity strength in the striatum preferentially increased in post-septic males but remained near baseline in post-septic female mice. Additionally, the female mice showed reduced network connectivity alterations in the projections from periaqueductal gray to the superior colliculus as also between the anterior cingulate cortex and the striatum. Coupled with the sustained intracerebral gliosis response, the intra-striatal fMRI response patterns in males could signify a delayed recovery from sepsis. Together, our study provides evidence that peripheral sepsis influences peripheral immunity, brain immunity and brain connectivity in a sex-dependent manner, with the fMRI response strongly indicating cognitive benefits in young females recovering from sepsis relative to their male counterparts.

Leaky Gut Syndrome Along With Clostridium perfringens Bacteremia in a Neurodegenerative Disease Patient: A Case Report

Leaky gut syndrome (LGS) is caused by intestinal epithelial injury and increased intestinal permeability due to a variety of factors, including chronic stress, inflammatory bowel disease, diabetes, surgery, and chemotherapy, resulting in an increased influx of matter from the intestinal lumen causing constipation and bacteremia. To our knowledge, this is the first known case of LGS along with Clostridium perfringens (C. perfringens) bacteremia in a neurodegenerative disease patient. The patient was an 81-year-old male with a history of Alzheimer's disease, cerebral infarction, and diverticulitis in a psychiatric hospital, fed via a nasogastric tube. During hospitalization, he developed a 37.4℃ temperature and disturbance of consciousness evaluated as 3 points on the Glasgow Coma Scale. A follow-up blood examination revealed a white blood cell count of 29,000/µL and a C-reactive protein value of 11.2 mg/dL. Computed tomography revealed an increased concentration of peripheral adipose tissue from the sigmoid colon to the rectum and significant quantities of stool in the rectum. Treatment was initiated with doripenem (DRPM) for sepsis of unknown focus. C. perfringens was subsequently identified in both two blood culture tests. He improved with decreased inflammatory response; DRPM was terminated after 14 days. He remains free of recurrence. We speculate that the LGS in this case may have developed from dopaminergic neuronal decrease and impaired amino acid metabolism caused by chronic hypo-inflammation due to neurodegenerative disease (Alzheimer's disease). We report the first known case of LGS along with C. perfringens bacteremia in a neurodegenerative disease patient.

Presence of Pseudomonas aeruginosa in feces exacerbate leaky gut in mice with low dose dextran sulfate solution, impacts of specific bacteria

The impact of Pseudomonas aeruginosa (PA) was explored in a mouse model with non-diarrheal gut permeability defect using 1.5% dextran sulfate solution (DSS) plus antibiotics (ATB) with or without orally administered PA. As such, ATB+DSS+PA mice induced more severe intestinal injury as indicated by stool consistency and leaky gut (FITC-dextran assay, bacteremia, and endotoxemia) with an increase in serum cytokines, liver enzyme, and hepatocyte apoptosis when compared with ATB+DSS mice. There was no abnormality by these parameters in the non-DSS group, including water alone (control), antibiotics alone (ATB+water), and antibiotics with PA (ATB+water+PA). Despite a similarly fecal microbiome patterns between ATB+DSS and ATB+DSS+PA groups, a higher abundance of Pseudomonas, Enterococci, and Escherichia-Shigella was detected in ATB+DSS+PA mice. Additionally, the additive pro-inflammation between pathogen molecules, using heat-killed P. aeruginosa preparations, and LPS against enterocytes (Caco2) and hepatocytes (HegG2), as indicated by supernatant IL-8 and expression of several genes (IL-8, NF-kB, and NOS2) are demonstrated. In conclusion, presence of P. aeruginosa in the gut exacerbated DSS-induced intestinal injury with spontaneous translocation of LPS and bacteria from the gut into the blood circulation (leaky gut) that induced more severe systemic inflammation. The presence of pathogenic bacteria, especially PA in stool of the healthy individuals might have some adverse effect. More studies are in needed.

Understanding dental pulp inflammation: from signaling to structure

The pulp is a unique tissue within each tooth that is susceptible to painful inflammation, known as pulpitis, triggered by microbial invasion from carious lesions or trauma that affect many individuals. The host response involves complex immunological processes for pathogen defense and dentin apposition at the site of infection. The interplay of signaling between the immune and non-immune cells via cytokines, chemokines, neuropeptides, proteases, and reactive nitrogen and oxygen species leads to tissue reactions and structural changes in the pulp that escalate beyond a certain threshold to irreversible tissue damage. If left untreated, the inflammation, which is initially localized, can progress to pulpal necrosis, requiring root canal treatment and adversely affecting the prognosis of the tooth. To preserve pulp vitality and dental health, a deeper understanding of the molecular and cellular mechanisms of pulpitis is imperative. In particular, elucidating the links between signaling pathways, clinical symptoms, and spatiotemporal spread is essential to develop novel therapeutic strategies and push the boundaries of vital pulp therapy.

Aging-induced dysbiosis worsens sepsis severity but is attenuated by probiotics in D-galactose-administered mice with cecal ligation and puncture model

INTRODUCTION

Despite the well-established effects of aging on brain function and gut dysbiosis (an imbalance in gut microbiota), the influence of aging on sepsis-associated encephalopathy (SAE) and the role of probiotics in this context remain less understood.

METHODS

C57BL/6J mice (8-week-old) were subcutaneously administered with 8 weeks of D-galactose (D-gal) or phosphate buffer solution (PBS) for aging and non-aging models, respectively, with or without 8 weeks of oral Lacticaseibacillus rhamnosus GG (LGG). Additionally, the impact of the condition media from LGG (LCM) was tested in macrophages (RAW 264.7 cells), microglia (BV-2 cells), and hippocampal cells (HT-22 cells).

RESULT

Fecal microbiome analysis demonstrated D-gal-induced dysbiosis (reduced Firmicutes and Desulfobacterota with increased Bacteroidota and Verrucomicrobiota), which LGG partially neutralized the dysbiosis. D-gal also worsens cecal ligation and puncture (CLP) sepsis severity when compared with PBS-CLP mice, as indicated by serum creatinine (Scr) and alanine transaminase (ALT), but not mortality, neurological characteristics (SHIRPA score), and serum cytokines (TNF-α and IL-6). Additionally, D-gal-induced aging was supported by fibrosis in the liver, kidney, and lung; however, CLP sepsis did not worsen fibrosis. Interestingly, LGG attenuated all parameters (mortality, Scr, ALT, SHIRPA, and cytokines) in non-aging sepsis (PBS-CLP) while improving all these parameters, except for mortality and serum IL-6, in aging sepsis (D-gal CLP). For the in vitro test using lipopolysaccharide (LPS) stimulation, LCM attenuated inflammation in some parameters on RAW264.7 cells but not BV-2 and HT-22 cells, implying a direct anti-inflammatory effect of LGG on macrophages, but not in cells from the brain.

CONCLUSION

D-gal induced fecal dysbiosis and worsened sepsis severity as determined by Scr and ALT, and LGG could alleviate most of the selected parameters of sepsis, including SAE. However, the impact of LGG on SAE was not a direct delivery of beneficial molecules from the gut to the brain but partly due to the attenuation of systemic inflammation through the modulation of macrophages.

Differential gut microbiota composition in β-Thalassemia patients and its correlation with iron overload

Recent research highlights the significant impact of the gut microbiota on health and disease. Thalassemia, a hereditary blood disorder, requires regular blood transfusions, leading to an accumulation of iron in the body. Such changes could potentially alter the intestinal microbiota, thereby increasing the susceptibility of thalassemic patients to infection. In this study, we analyzed the fecal microbiota of 70 non-transfusion-dependent (NTDT) β-thalassemia/HbE patients and 30 healthy controls. Our findings indicate that iron chelation intervention had no detectable effect on the microbiome profile of thalassemic patients. However, the cross-sectional analysis revealed that the bacterial diversity and community structure in patients were significantly less diverse and distinct compared to those of healthy subjects. Using reference frames, we were also able to demonstrate that bacterial taxa that are known to produce short chain fatty acids, from the genera Alistipes, Coprococcus, and Oscillospira, and those from the family Ruminococcaceae, were less prevalent in the patients. In contrast, bacterial taxa associated with an unhealthy gut, including the genus Clostridium and those from the families Fusobacteriaceae, Enterobacteriaceae, and Peptostrptococcaceae, were more prevalent in patients and found to be correlated with higher levels of ferritin. Collectively, these changes in the microbiota could be regarded as markers of raised ferritin levels, and therefore, awareness should be exercised as they could interfere, albeit indirectly, with the treatment of the co-morbidities of thalassemia.

Progress in the study of the correlation between sepsis and intestinal microecology

Sepsis, a disease with high incidence, mortality, and treatment costs, has a complex interaction with the gut microbiota. With advances in high-throughput sequencing technology, the relationship between sepsis and intestinal dysbiosis has become a new research focus. However, owing to the intricate interplay between critical illness and clinical interventions, it is challenging to establish a causal relationship between sepsis and intestinal microbiota imbalance. In this review, the correlation between intestinal microecology and sepsis was summarized, and new therapies for sepsis intervention based on microecological target therapy were proposed, and the shortcomings of bacterial selection and application timing in clinical practice were addressed. In conclusion, current studies on metabolomics, genomics and other aspects aimed at continuously discovering potential probiotics are all providing theoretical basis for restoring intestinal flora homeostasis for subsequent treatment of sepsis.

Compartmentalization of the inflammatory response during bacterial sepsis and severe COVID-19

Acute infections cause local and systemic disorders which can lead in the most severe forms to multi-organ failure and eventually to death. The host response to infection encompasses a large spectrum of reactions with a concomitant activation of the so-called inflammatory response aimed at fighting the infectious agent and removing damaged tissues or cells, and the anti-inflammatory response aimed at controlling inflammation and initiating the healing process. Fine-tuning at the local and systemic levels is key to preventing local and remote injury due to immune system activation. Thus, during bacterial sepsis and Coronavirus disease 2019 (COVID-19), concomitant systemic and compartmentalized pro-inflammatory and compensatory anti-inflammatory responses are occurring. Immune cells (e.g., macrophages, neutrophils, natural killer cells, and T-lymphocytes), as well as endothelial cells, differ from one compartment to another and contribute to specific organ responses to sterile and microbial insult. Furthermore, tissue-specific microbiota influences the local and systemic response. A better understanding of the tissue-specific immune status, the organ immunity crosstalk, and the role of specific mediators during sepsis and COVID-19 can foster the development of more accurate biomarkers for better diagnosis and prognosis and help to define appropriate host-targeted treatments and vaccines in the context of precision medicine.

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.

Case report: Catastrophic event: neonatal gastric perforation and complication of capillary leak syndrome

Neonatal gastric perforation (NGP) is a rare, but life-threatening condition that can lead to serious conditions, such as capillary leak syndrome (CLS). Here, we present the case of a preterm male infant with NGP complicated by CLS after stomach repair. The patient was born at 33 2/7 weeks, weighed 1,770 g, and was diagnosed with respiratory distress syndrome. On the fourth day of life, the patient presented with distention and an unstable cardiovascular system. Routine blood tests revealed a white blood cell count of 2.4 × 109/L. Chest and abdominal radiography revealed a pneumoperitoneum, suggesting a gastrointestinal perforation. The patient was urgently transferred to a tertiary hospital for exploratory laparotomy, where a 2 cm diameter perforation was discovered in the stomach wall and subsequently repaired. Pathological findings indicated the absence of a muscular layer in the stomach wall. The patient unexpectedly developed CLS postoperatively, leading to multiorgan dysfunction and eventual death. The underlying pathological mechanism of NGP-induced CLS may be related to severe chemical peritonitis, sepsis, endothelial glycocalyx dysfunction, enhanced systemic inflammation, and translocation of the gut microbiota, causing endothelial hyperpermeability. Notablely, abdominal surgery itself can be a significant triggering factor for CLS occurrence. Complications of NGP and CLS are extremely dangerous. Investigating the mechanism by which NGP triggers CLS could potentially improve the prognosis. Conservative treatment for pneumoperitoneum secondary to gastric perforation may be a reasonable option, especially when the condition of the patient is unstable.

Blood virome of patients with traumatic sepsis

Sepsis is one of the possible outcomes of severe trauma, and it poses a dire threat to human life, particularly in immunocompromised people. The most prevalent pathogens are bacteria and fungi, but viruses should not be overlooked. For viral metagenomic analysis, we collected blood samples from eight patients with post-traumatic sepsis before and seven days after treatment. The results demonstrated that Anellovirus predominated the viral community, followed by Siphoviridae and Myoviridae, and that the variations in viral community and viral load before and after treatment were not statistically significant. This study allows us to investigate methods for establishing NGS-based viral diagnostic instruments for detecting viral infections in the blood of sepsis patients so that antiviral therapy can be administered quickly.

New Insights into Photobiomodulation of the Vaginal Microbiome-A Critical Review

The development of new technologies such as sequencing has greatly enhanced our understanding of the human microbiome. The interactions between the human microbiome and the development of several diseases have been the subject of recent research. In-depth knowledge about the vaginal microbiome (VMB) has shown that dysbiosis is closely related to the development of gynecologic and obstetric disorders. To date, the progress in treating or modulating the VMB has lagged far behind research efforts. Photobiomodulation (PBM) uses low levels of light, usually red or near-infrared, to treat a diversity of conditions. Several studies have demonstrated that PBM can control the microbiome and improve the activity of the immune system. In recent years, increasing attention has been paid to the microbiome, mostly to the gut microbiome and its connections with many diseases, such as metabolic disorders, obesity, cardiovascular disorders, autoimmunity, and neurological disorders. The applicability of PBM therapeutics to treat gut dysbiosis has been studied, with promising results. The possible cellular and molecular effects of PBM on the vaginal microbiome constitute a theoretical and promising field that is starting to take its first steps. In this review, we will discuss the potential mechanisms and effects of photobiomodulation in the VMB.

Less Severe Polymicrobial Sepsis in Conditional mgmt-Deleted Mice Using LysM-Cre System, Impacts of DNA Methylation and MGMT Inhibitor in Sepsis

The O6-methylguanine-DNA methyltransferase (MGMT) is a DNA suicide repair enzyme that might be important during sepsis but has never been explored. Then, the proteomic analysis of lipopolysaccharide (LPS)-stimulated wild-type (WT) macrophages increased proteasome proteins and reduced oxidative phosphorylation proteins compared with control, possibly related to cell injury. With LPS stimulation, mgmt null (mgmt^flox/flox; LysM-Cre^cre/-) macrophages demonstrated less profound inflammation; supernatant cytokines (TNF-α, IL-6, and IL-10) and pro-inflammatory genes (iNOS and IL-1β), with higher DNA break (phosphohistone H2AX) and cell-free DNA, but not malondialdehyde (the oxidative stress), compared with the littermate control (mgmt^flox/flox; LysM-Cre^-/-). In parallel, mgmt null mice (MGMT loss only in the myeloid cells) demonstrated less severe sepsis in the cecal ligation and puncture (CLP) model (with antibiotics), as indicated by survival and other parameters compared with sepsis in the littermate control. The mgmt null protective effect was lost in CLP mice without antibiotics, highlighting the importance of microbial control during sepsis immune modulation. However, an MGMT inhibitor in CLP with antibiotics in WT mice attenuated serum cytokines but not mortality, requiring further studies. In conclusion, an absence of mgmt in macrophages resulted in less severe CLP sepsis, implying a possible influence of guanine DNA methylation and repair in macrophages during sepsis.