Sex differences associate with late microbiome alterations after murine surgical sepsis

Gut mycobiome dysbiosis after sepsis and trauma

BACKGROUND

Sepsis and trauma are known to disrupt gut bacterial microbiome communities, but the impacts and perturbations in the fungal (mycobiome) community after severe infection or injury, particularly in patients experiencing chronic critical illness (CCI), remain unstudied.

METHODS

We assess persistence of the gut mycobiome perturbation (dysbiosis) in patients experiencing CCI following sepsis or trauma for up to two-to-three weeks after intensive care unit hospitalization.

RESULTS

We show that the dysbiotic mycobiome arrays shift toward a pathobiome state, which is more susceptible to infection, in CCI patients compared to age-matched healthy subjects. The fungal community in CCI patients is largely dominated by Candida spp; while, the commensal fungal species are depleted. Additionally, these myco-pathobiome arrays correlate with alterations in micro-ecological niche involving specific gut bacteria and gut-blood metabolites.

CONCLUSIONS

The findings reveal the persistence of mycobiome dysbiosis in both sepsis and trauma settings, even up to two weeks post-sepsis and trauma, highlighting the need to assess and address the increased risk of fungal infections in CCI patients.

Sex-specific intestinal dysbiosis persists after multicompartmental injury

BACKGROUND

Preclinical studies of the gut microbiome after severe traumatic injury have demonstrated severe dysbiosis in males, with sex-specific microbial differences up to 2 days after injury. However, the impact of host sex on injury-driven dysbiosis over time remains unknown. We hypothesized that sex-specific differences in intestinal microbiome diversity and composition after traumatic injury with and without stress would persist after 7 days.

METHODS

Male and proestrus female Sprague-Dawley rats (n = 8/group) were subjected to either polytrauma (lung contusion, hemorrhagic shock, cecectomy, bifemoral pseudofractures), polytrauma plus chronic restraint stress, or naïve controls. The fecal microbiome was measured on days 0, 3, and 7 using 16S rRNA sequencing and Quantitative Insights into Microbial Ecology bioinformatics analyses. Microbial alpha-diversity (Chao1 and Shannon indices) and beta-diversity were assessed. Analyses were performed in GraphPad and "R," with significance defined as P < .05.

RESULTS

Polytrauma and polytrauma plus chronic restraint stress reduced alpha-diversity (Chao1, Shannon) within 3 days postinjury, which persisted up to day 7 in both sexes; polytrauma and polytrauma plus chronic restraint stress females had significantly decreased Chao1 compared to male counterparts at day 7 (P = .02). At day 7, the microbiome composition in polytrauma females had higher proportion of Mucispirillum, whereas polytrauma plus chronic restraint stress males demonstrated elevated abundance of Ruminococcus and Akkermansia.

CONCLUSION

Multicompartmental trauma induces intestinal dysbiosis that is sex-specific with persistence of decreased diversity and unique "pathobiome" signatures in females after 1 week. These findings underline sex as an important biological variable that may influence variable host-specific responses and outcomes after severe trauma and critical illness. This underscores the need to consider precision medicine strategies to ameliorate these outcomes.

Targeting sting to reduce sepsis-induced acute intestinal injury

BACKGROUND

Sepsis is a dysregulated host response to infection syndrome leading to life-threatening organ dysfunction. Sepsis-induced intestinal dysfunction is a key element in the progression to multisystem organ failure. The stimulator of interferon genes is an intracellular protein implicated in intestinal injury in sepsis. H151, a small molecule inhibitor of stimulator of interferon genes, has not yet been studied as a potential therapeutic in sepsis. We hypothesize that H151 therapeutically reduces sepsis-induced acute intestinal injury.

METHODS

Male mice underwent cecal ligation and puncture and were treated with intraperitoneal H151 (10 mg/kg body weight) or vehicle. Intestines and serum were collected for analysis 20 hours after cecal ligation and puncture. Oral gavage of mice with FITC-dextran was performed 15 hours after cecal ligation and puncture. Five hours after gavage, serum was collected, and intestinal permeability was assessed. Mice were monitored for 10 days after cecal ligation and puncture to assess survival.

RESULTS

Zonula occludens 1 tight junctional protein expression was reduced after cecal ligation and puncture and recovered with H151 treatment. This was associated with a 62.3% reduction in intestinal permeability as assessed by fluorimetry. After cecal ligation and puncture, treatment with H151 was associated with a 58.7% reduction in intestinal histopathologic injury (P < .05) and a 56.6% reduction in intestinal apoptosis (P < .05). Intestinal myeloperoxidase activity was decreased by 70.8% after H151 treatment (P < .05). Finally, H151 improved 10-day survival from 33% to 80% after cecal ligation and puncture (P = .011).

CONCLUSION

H151, a novel stimulator of interferon genes inhibitor, reduces intestinal injury, inflammation, and permeability when administered as a treatment for cecal ligation and puncture-induced sepsis. Thus, targeting stimulator of interferon genes shows promise as a therapeutic strategy to ameliorate sepsis-induced acute intestinal injury.

Association of Sex and Age with Mortality and Health-Related Quality of Life in Children with Septic Shock: A Secondary Analysis of the Life After Pediatric Sepsis Evaluation

Introduction: Sepsis is more common in males than females, but whether outcomes differ by sex in various pediatric age groups is unclear. The Life After Pediatric Sepsis Evaluation (LAPSE) was a multicenter prospective cohort study that evaluated health-related quality of life (HRQL) in children after community-acquired septic shock. In this secondary analysis, we evaluated whether male children are at increased risk of mortality or long-term decline in HRQL than female children by age group. Methods: Children (1 month-18 years) with community-acquired septic shock were recruited from 12 pediatric intensive care units in the U.S. Data included sex, age group (<1 year, 1-<13 years, 13-18 years), acute illness severity (acute organ dysfunction and inflammation), and longitudinal assessments of HRQL and mortality. Persistent decline in HRQL was defined as a 10% decrease in HRQL comparing baseline to 3 months following admission. Male and female children were stratified by age group and compared to evaluate the difference in the composite outcome of death or persistent decline in HRQL using the Cochran-Mantel-Haenszel test. Results: Of 389 children, 54.2% (n = 211) were male. Overall, 10% (21/211) of males and 12% (22/178) of females died by 3 months (p = 0.454). Among children with follow-up data, 41% (57/138) of males and 44% (48/108) of females died or had persistent decline in HRQL at 3 months (p = 0.636), with no observed difference by sex when stratified by age group. There was no significant difference in acute illness severity between males and females overall or stratified by age group. Conclusions: In this secondary analysis of the LAPSE cohort, HRQL, and mortality were not different between male and female children when stratified by age group. There were no significant differences by sex across multiple measures of illness severity or treatment intensity.

Sex, sepsis and the brain: defining the role of sexual dimorphism on neurocognitive outcomes after infection

Sexual dimorphisms exist in multiple domains, from learning and memory to neurocognitive disease, and even in the immune system. Male sex has been associated with increased susceptibility to infection, as well as increased risk of adverse outcomes. Sepsis remains a major source of morbidity and mortality globally, and over half of septic patients admitted to intensive care are believed to suffer some degree of sepsis-associated encephalopathy (SAE). In the short term, SAE is associated with an increased risk of in-hospital mortality, and in the long term, has the potential for significant impairment of cognition, memory, and acceleration of neurocognitive disease. Despite increasing information regarding sexual dimorphism in neurologic and immunologic systems, research into these dimorphisms in sepsis-associated encephalopathy remains critically understudied. In this narrative review, we discuss how sex has been associated with brain morphology, chemistry, and disease, sexual dimorphism in immunity, and existing research into the effects of sex on SAE.

Interactions between Gender and Sepsis—Implications for the Future

Sex and gender dimorphisms are found in a large variety of diseases, including sepsis and septic shock which are more prevalent in men than in women. Animal models show that the host response to pathogens differs in females and males. This difference is partially explained by sex polarization of the intracellular pathways responding to pathogen–cell receptor interactions. Sex hormones seem to be responsible for this polarization, although other factors, such as chromosomal effects, have yet to be investigated. In brief, females are less susceptible to sepsis and seem to recover more effectively than males. Clinical observations produce more nuanced findings, but men consistently have a higher incidence of sepsis, and some reports also claim higher mortality rates. However, variables other than hormonal differences complicate the interaction between sex and sepsis, including comorbidities as well as social and cultural differences between men and women. Conflicting data have also been reported regarding sepsis-attributable mortality rates among pregnant women, compared with non-pregnant females. We believe that unraveling sex differences in the host response to sepsis and its treatment could be the first step in personalized, phenotype-based management of patients with sepsis and septic shock.

Multicompartmental traumatic injury and the microbiome: Shift to a pathobiome

BACKGROUND

Previous animal models have demonstrated altered gut microbiome after mild traumatic injury; however, the impact of injury severity and critical illness is unknown. We hypothesized that a rodent model of severe multicompartmental injuries and chronic stress would demonstrate microbiome alterations toward a "pathobiome" characterized by an overabundance of pathogenic organisms, which would persist 1 week after injury.

METHODS

Male Sprague-Dawley rats (n = 8 per group) were subjected to either multiple injuries (PT) (lung contusion, hemorrhagic shock, cecectomy, and bifemoral pseudofractures), PT plus daily chronic restraint stress for 2 hours (PT/CS), or naive controls. Fecal microbiome was measured on days 0, 3, and 7 using high-throughput 16S rRNA sequencing and Quantitative Insights Into Microbial Ecology 2 bioinformatics analysis. Microbial α diversity was assessed using Chao1 and Shannon indices, and β diversity with principle coordinate analysis. Intestinal permeability was evaluated by plasma occludin; ileum and descending colon tissues were reviewed for injury. Analyses were performed in GraphPad (GraphPad Software, La Jolla, CA) and R (R Foundation for Statistical Computing, Vienna, Austria), with significance defined as p < 0.05.

RESULTS

There were significant alterations in β diversity at day 3 and between all groups. By day 3, both PT and PT/CS demonstrated significantly depleted bacterial diversity (Chao1) ( p = 0.01 and p = 0.001, respectively) versus naive, which persisted up to day 7 in PT/CS only ( p = 0.001). Anaerostipes and Rothia dominated PT and Lactobacillus bloomed in PT/CS cohorts by day 7. Plasma occludin was significantly elevated in PT/CS compared with naive ( p = 0.04), and descending colon of both PT and PT/CS showed significantly higher injury compared with naive ( p = 0.005, p = 0.006).

CONCLUSIONS

Multiple injuries with and without chronic stress induces significant alterations in microbiome diversity and composition within 3 days; these changes are more prominent and persist for 1 week postinjury with stress. This rapid and persistent transition to a "pathobiome" phenotype represents a critical phenomenon that may influence outcomes after severe trauma and critical illness.