Systematic Review of Gender Differences in Sepsis Management and Outcomes

PRE-ADMISSION BARIATRIC SURGERY IS ASSOCIATED WITH REDUCED MORTALITY IN SURGICAL PATIENTS WITH SEPSIS

ABSTRACT

Background: Obesity is associated with higher 90-day mortality compared to nonobese surgical patients. Bariatric surgery (BS) can reduce obesity-related comorbidities, even in those with persistent obesity. Objective: Evaluate the impact of prior BS on sepsis outcomes in surgical patients with obesity. Setting: University Hospital, United States. Methods: A single-institution retrospective review of all surgical patients with sepsis (SOFA≥2) was conducted. Patients were grouped into people with obesity and prior BS (OB/BS; n = 48), people with obesity without BS (OB; n = 717), nonobese (NOB; n = 574), and nonobese with prior BS (NOB/BS; n = 27). Demographic data, comorbidities, and sepsis presentation were compared. The primary outcome was cumulative 90-day mortality and survival. Results: Most OB/BS patients underwent gastric bypass <5 years from admission (61%). The OB/BS group was younger, more likely to be female, and transferred from an outside hospital. The mean BMI was highest in the OB/BS group (46.3± 14.7 kg/m 2 , P < 0.0005). Charlson Comorbidity Index was lower in the OB/BS and NOB/BS groups (2 (1-4) and 2 (2-4), respectively, P = 0.0033). Cumulative 90-day mortality was significantly lower in the OB/BS cohort (20.8%, P = 0.002). The OB/BS cohort was more likely to die from intra-abdominal sepsis not amenable to source control (60% vs. 22.5% vs. 22.8% vs. 37.5%, P = 0.04). Compared to the other groups, 90-day survival was highest in the OB/BS cohort (log-rank P < 0.009). Conclusions: This study demonstrated improvement in 90-day survival in OB/BS patients despite higher BMIs. However, this group was more likely to die from intra-abdominal sources, likely reflecting surgical complexity in the setting of prior bypasses.

SEX DIFFERENCES IN SEPSIS-RELATED ACUTE RESPIRATORY DISTRESS SYNDROME AND OTHER SHORT-TERM OUTCOMES AMONG CRITICALLY ILL PATIENTS WITH SEPSIS: A RETROSPECTIVE STUDY IN CHINA

ABSTRACT

Background: The evidence of sex disparity in acute respiratory distress syndrome (ARDS) is scarce and varies widely. Objective: This observational, retrospective study aimed to determine the effect of sex on the sepsis-related ARDS and other short outcomes in critically ill patients with sepsis. Methods: A total of 2,111 adult patients with sepsis who were admitted to three central intensive care units (ICUs) of Wuhan Tongji Hospital between 2012 and 2022 were included in our analysis. Sex was considered as an exposure factor, with sepsis-related ARDS as the primary outcome, and in-hospital mortality, invasive mechanical ventilation support, septic shock, and other complications as secondary outcomes. Results: Among the 2,111 enrolled patients, 1,287 were males (61%) and 824 were females (39%). The incidence of sepsis-related ARDS was higher in males compared to females ( P = 0.001), as well as in-hospital mortality ( P = 0.009). Multivariate logistic analysis demonstrated that male sex remained independently associated with an increased risk of sepsis-related ARDS (adjusted odds ratio [aOR] = 1. 493 [1.034-2.156], P = 0.032). Propensity score matching analysis also indicated that males had 58% higher odds of developing sepsis-related ARDS (aOR = 1.584 [1.022-2.456], P = 0.040). Regarding secondary outcomes, male sex was identified as a risk factor for in-hospital mortality (aOR = 1.536 [1.087-2.169], P = 0.015) and invasive mechanical ventilation support (aOR = 1.313 [1.029-1.674], P = 0.028) in the fully adjusted model. Sensitivity analysis that included postmenopausal females and age-matched male counterparts showed that male sex still remained to be a risk factor of developing sepsis-related ARDS (aOR = 1.968 [1.241-3.120], P = 0.004). Conclusions: Male sex was identified as an independent risk factor for sepsis-related ARDS and in-hospital mortality among critically ill patients with sepsis. Given the retrospective design of this study, the relationship between sex and sepsis-related ARDS requires further validation through large-scale randomized controlled trials in the future.

A predictive model for 28-day mortality after discharge in patients with sepsis associated with cerebrovascular disease

BACKGROUND

The present study investigated the association between cerebrovascular diseases and sepsis, including its occurrence, progression, and impact on mortality. However, there is currently a lack of predictive models for 28-day mortality in patients with cerebrovascular disease associated with sepsis.

OBJECTIVE

The objective of this study is to examine the mortality rate within 28 days after discharge in this population, while concurrently developing a corresponding predictive model.

METHODS

The data for this retrospective cohort study were obtained from the MIMIC-IV database. Patients with sepsis and cerebrovascular disease in the ICU were included. Laboratory indicators, vital signs, and demographic data were collected within 24 hours of ICU admission. Mortality rates within 28 days after discharge were calculated based on patient death times. Logistic regression analysis was used to identify potential variables for a predictive model. A nomogram visualized the prediction model. The performance of the model was evaluated using ROC curves, Calibration plots, and DCA.

RESULTS

The study enrolled a total of 2660 patients diagnosed with cerebrovascular disease complicated by sepsis, consisting of 1434 males (53.91%) with a median age of 70.97 (59.60, 80.73). Among this cohort of patients, a total of 751 fatalities occurred within 28 days following discharge. The multivariate regression analysis revealed that age, creatinine, arterial oxygen partial pressure (Pa O2), arterial carbon dioxide partial pressure (Pa CO2), respiratory rate, white blood cell (WBC) count, Body Mass Index (BMI), and race demonstrated potential predictive variables. The aforementioned model yielded an area under the ROC curve of 0.744, accompanied by a sensitivity of 66.2% and specificity of 71.2%. Furthermore, both calibration plots and DCA demonstrated robust performance in practical applications.

CONCLUSION

The proposed prediction model allows clinicians to promptly assess the mortality risk in patients with cerebrovascular disease complicated by sepsis within 28 days after discharge, facilitating early intervention strategies. Consequently, clinicians can implement additional advantageous medical interventions for individuals with cerebrovascular disease and sepsis.

Sex differences in pediatric sepsis-a systematic review protocol

BACKGROUND

Pediatric sepsis remains a leading cause of childhood morbidity and mortality worldwide. Despite advancements in modern medicine, it accounts for more than 3 million childhood deaths per year. Multiple studies have emphasized that sex and gender have an impact on the treatment and outcome of various diseases. Adult studies have revealed sex differences in pathophysiological responses to septic shock, as well as a possible protective effect of estrogens on critical illness. Sex-specific maturational and developmental differences in host immunology have been previously demonstrated for neonatal and pediatric age groups. At present, there are no studies assessing the impact of sex on outcomes of children with sepsis.

METHODS

The goal of this study is to assess sex-specific differences in childhood sepsis survival outcomes. We will systematically assess associations of sex and gender with outcomes in pediatric sepsis in the literature by performing a systematic search of MEDLINE and Embase databases. We will include all English language randomized trials and cohort studies. The study population will include children > 37 weeks gestational age and < 18 years of age. Exposure will be sepsis, severe sepsis, and septic shock and the main comparison will be between male and female sex. The primary outcome will be hospital mortality. Secondary outcomes will be the pediatric intensive care unit and hospital length of stay.

DISCUSSION

Results from this review are expected to provide important information on the association of sex with the outcomes of pediatric sepsis. If an association is noted, this study may serve as a foundation for further research evaluating the pathophysiological aspects as well as potential socioeconomic factors responsible for the clinically detected sex differences.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42022315753.

Sex differences in the use of mechanical ventilation in a neurointensive care population: a retrospective study

BACKGROUND

In the general intensive care unit (ICU) women receive invasive mechanical ventilation (IMV) less frequently than men. We investigated whether sex differences in the use of IMV also exist in the neurocritical care unit (NCCU), where patients are intubated not only due to respiratory failure but also due to neurological impairment.

METHODS

This retrospective single-centre study included adults admitted to the NCCU of the University Hospital Zurich between January 2018 and August 2021 with neurological or neurosurgical main diagnosis. We collected data on demographics, intubation, re-intubation, tracheotomy, and duration of IMV or other forms of respiratory support from the Swiss ICU registry or the medical records. A descriptive statistics was performed. Baseline and outcome characteristics were compared by sex in the whole population and in subgroup analysis.

RESULTS

Overall, 963 patients were included. No differences between sexes in the use and duration of IMV, frequency of emergency or planned intubations, tracheostomy were found. The duration of oxygen support was longer in women (men 2 [2, 4] vs. women 3 [1, 6] days, p = 0.018), who were more often admitted due to subarachnoid hemorrhage (SAH). No difference could be found after correction for age, diagnosis of admission and severity of disease.

CONCLUSION

In this NCCU population and differently from the general ICU population, we found no difference by sex in the frequency and duration of IMV, intubation, reintubation, tracheotomy and non-invasive ventilation support. These results suggest that the differences in provision of care by sex reported in the general ICU population may be diagnosis-dependent. The difference in duration of oxygen supplementation observed in our population can be explained by the higher prevalence of SAH in women, where we aim for higher oxygenation targets due to the specific risk of vasospasm.

Hospital-Onset Sepsis Warrants Expanded Investigation and Consideration as a Unique Clinical Entity

Sepsis causes more than a quarter million deaths among hospitalized adults in the United States each year. Although most cases of sepsis are present on admission, up to one-quarter of patients with sepsis develop this highly morbid and mortal condition while hospitalized. Compared with patients with community-onset sepsis (COS), patients with hospital-onset sepsis (HOS) are twice as likely to require mechanical ventilation and ICU admission, have more than two times longer ICU and hospital length of stay, accrue five times higher hospital costs, and are twice as likely to die. Patients with HOS differ from those with COS with respect to underlying comorbidities, admitting diagnosis, clinical manifestations of infection, and severity of illness. Despite the differences between these patient populations, patients with HOS sepsis are understudied and warrant expanded investigation. Here, we outline important knowledge gaps in the recognition and management of HOS in adults and propose associated research priorities for investigators. Of particular importance are questions regarding standardization of research and clinical case identification, understanding of clinical heterogeneity among patients with HOS, development of tailored management recommendations, identification of impactful prevention strategies, optimization of care delivery and quality metrics, identification and correction of disparities in care and outcomes, and how to ensure goal-concordant care for patients with HOS.

Lack of compensatory mitophagy in skeletal muscles during sepsis

Skeletal muscle dysfunction is a major problem in critically ill patients suffering from sepsis. This condition is associated with mitochondrial dysfunction and increased autophagy in skeletal muscles. Autophagy is a proteolytic mechanism involved in eliminating dysfunctional cellular components, including mitochondria. The latter process, referred to as mitophagy, is essential for maintaining mitochondrial quality and skeletal muscle health. Recently, a fluorescent reporter system called mito-QC (i.e. mitochondrial quality control) was developed to specifically quantify mitophagy levels. In the present study, we used mito-QC transgenic mice and confocal microscopy to morphologically monitor mitophagy levels during sepsis. To induce sepsis, Mito-QC mice received Escherichia coli lipopolysaccharide (10 mg kg-1 i.p.) or phosphate-buffered saline and skeletal muscles (hindlimb and diaphragm) were excised 48 h later. In control groups, there was a negative correlation between the basal mitophagy level and overall muscle mitochondrial content. Sepsis increased general autophagy in both limb muscles and diaphragm but had no effect on mitophagy levels. Sepsis was associated with a downregulation of certain mitophagy receptors (Fundc1, Bcl2L13, Fkbp8 and Phbb2). The present study suggests that general autophagy and mitophagy can be dissociated from one another, and that the characteristic accumulation of damaged mitochondria in skeletal muscles under the condition of sepsis may reflect a failure of adequate compensatory mitophagy. KEY POINTS: There was a negative correlation between the basal level of skeletal muscle mitophagy and the mitochondrial content of individual muscles. Mitophagy levels in limb muscles and the diaphragm were unaffected by lipopolysaccharide (LPS)-induced sepsis. With the exception of BNIP3 in sepsis, LPS administration induced either no change or a downregulation of mitophagy receptors in skeletal muscles.

Sex- and Gender-Based Analysis on Norepinephrine Use in Septic Shock: Why Is It Still a Male World?

Sex and gender are fundamental health determinants and their role as modifiers of treatment response is increasingly recognized. Norepinephrine is a cornerstone of septic shock management and its use is based on the highest level of evidence compared to dopamine. The related 2021 Surviving Sepsis Campaign (SCC) recommendation is presumably applicable to both females and males; however, a sex- and gender-based analysis is lacking, thus not allowing generalizable conclusions. This paper was aimed at exploring whether sex- and gender-disaggregated data are available in the evidence supporting this recommendation. For all the studies underpinning it, four pairs of authors, including a woman and a man, extracted data concerning sex and gender, according to the Sex and Gender Equity in Research guidelines. Nine manuscripts were included with an overall population of 2126 patients, of which 43.2% were females. No sex analysis was performed and gender was never reported. In conclusion, the present manuscript highlighted that the clinical studies underlying the SCC recommendation of NE administration in septic shock have neglected the likely role of sex and gender as modifiers of treatment response, thus missing the opportunity of sex- and gender-specific guidelines.

Platelet P2Y12 signalling pathway in the dysregulated immune response during sepsis

Sepsis is a complicated pathological condition in response to severe infection. It is characterized by a strong systemic inflammatory response, where multiple components of the immune system are involved. Currently, there is no treatment for sepsis. Blood platelets are known for their role in haemostasis, but they also participate in inflammation through cell-cell interaction and the secretion of inflammatory mediators. Interestingly, an increase in platelet activation, secretion, and aggregation with other immune cells (such as monocytes, T-lymphocytes and neutrophils) has been detected in septic patients. Therefore, antiplatelet therapy in terms of P2Y12 antagonists has been evaluated as a possible treatment for sepis. It was found that blocking P2Y12 receptors decreased platelet marker expression and limited attachment to immune cells in some studies, but not in others. This review addresses the role of platelets in sepsis and discusses whether antagonizing P2Y12 signalling pathways can alter the disease outcome. Challenges in studying P2Y12 antagonists in sepsis also are discussed. LINKED ARTICLES: This article is part of a themed issue on Platelet purinergic receptor and non-thrombotic disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.4/issuetoc.

The influence of gender on the epidemiology of and outcome from sepsis associated acute kidney injury in ICU: a retrospective propensity-matched cohort study

PURPOSES

The influence of gender on the epidemiology of and outcome from SA-AKI in ICU has not been fully clarified. Our aim is to elucidate these differences.

METHODS

This study included adult patients with sepsis in MIMIC IV (V 2.2), and propensity matching analysis, cox regression and logistic regression were used to analyze gender differences in incidence, mortality and organ support rate.

RESULTS

Of the 24,467 patients included in the cohort, 18,128 were retained after propensity score matching. In the matched cohort, the incidence of SA-AKI in males is higher than that in females (58.6% vs. 56.2%; P = 0.001).males were associated with a higher risk of SA-AKI (OR:1.07(1.01-1.14), P = 0.026;adjusted OR:1.07(1.01-1.14), P < 0.033).In SA-AKI patients, males were associated with a lower risk of ICU mortality(HR:0.803(0.721-0.893), P < 0.001;adjusted HR:0.836(0.746-0.937), P = 0.002) and in-hospital mortality(HR: 0.820(0.748-0.899), P < 0.001;adjusted HR:0.853(0.775-0.938), P = 0.003).there were no statistically significant differences between male and female patients in 1-year all-cause mortality (36.9% vs. 35.8%, P = 0.12), kidney replacement therapy rate (7.8% vs.7.4%, P = 0.547), mechanical ventilation rate 64.8% vs.63.9%, P = 0.369), and usage of vasoactive drugs (55.4% vs. 54.6%, P = 0.418).

CONCLUSIONS

Gender may affect the incidence and outcomes of SA-AKI, further research is needed to fully understand the impact of gender on SA-AKI patients.

Patient diversity and author representation in clinical studies supporting the Surviving Sepsis Campaign guidelines for management of sepsis and septic shock 2021: a systematic review of citations

BACKGROUND

The generalizability of the Surviving Sepsis Campaign (SSC) guidelines to various patient populations and hospital settings has been debated. A quantitative assessment of the diversity and representation in the clinical evidence supporting the guidelines would help evaluate the generalizability of the recommendations and identify strategic research goals and priorities. In this study, we evaluated the diversity of patients in the original studies, in terms of sex, race/ethnicity, and geographical location. We also assessed diversity in sex and geographical representation among study first and last authors.

METHODS

All clinical studies cited in support of the 2021 SSC adult guideline recommendations were identified. Original clinical studies were included, while editorials, reviews, non-clinical studies, and meta-analyses were excluded. For eligible studies, we recorded the proportion of male patients, percentage of each represented racial/ethnic subgroup (when available), and countries in which they were conducted. We also recorded the sex and location of the first and last authors. The World Bank classification was used to categorize countries.

RESULTS

The SSC guidelines included six sections, with 85 recommendations based on 351 clinical studies. The proportion of male patients ranged from 47 to 62%. Most studies did not report the racial/ ethnic distribution of the included patients; when they did so, most were White patients (68-77%). Most studies were conducted in high-income countries (77-99%), which included Europe/Central Asia (33-66%) and North America (36-55%). Moreover, most first/last authors were males (55-93%) and from high-income countries (77-99%).

CONCLUSIONS

To enhance the generalizability of the SCC guidelines, stakeholders should define strategies to enhance the diversity and representation in clinical studies. Though there was reasonable representation in sex among patients included in clinical studies, the evidence did not reflect diversity in the race/ethnicity and geographical locations. There was also lack of diversity among the first and last authors contributing to the evidence.

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-based analysis of treatment responses in animal models of sepsis: a preclinical systematic review protocol

BACKGROUND

The importance of investigating sex- and gender-dependent differences has been recently emphasized by major funding agencies. Notably, the influence of biological sex on clinical outcomes in sepsis is unclear, and observational studies suffer from the effect of confounding factors. The controlled experimental environment afforded by preclinical studies allows for clarification and mechanistic evaluation of sex-dependent differences. We propose a systematic review to assess the impact of biological sex on baseline responses to disease induction as well as treatment responses in animal models of sepsis. Given the lack of guidance surrounding sex-based analyses in preclinical systematic reviews, careful consideration of various factors is needed to understand how best to conduct analyses and communicate findings.

METHODS

MEDLINE and Embase will be searched (2011-present) to identify preclinical studies of sepsis in which any intervention was administered and sex-stratified data reported. The primary outcome will be mortality. Secondary outcomes will include organ dysfunction, bacterial load, and IL-6 levels. Study selection will be conducted independently and in duplicate by two reviewers. Data extraction will be conducted by one reviewer and audited by a second independent reviewer. Data extracted from included studies will be pooled, and meta-analysis will be conducted using random effects modeling. Primary analyses will be stratified by animal age and will assess the impact of sex at the following time points: pre-intervention, in response to treatment, and post-intervention. Risk of bias will be assessed using the SYRCLE's risk-of-bias tool. Illustrative examples of potential methods to analyze sex-based differences are provided in this protocol.

DISCUSSION

Our systematic review will summarize the current state of knowledge on sex-dependent differences in sepsis. This will identify current knowledge gaps that future studies can address. Finally, this review will provide a framework for sex-based analysis in future preclinical systematic reviews.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42022367726.

Sex differences in long-term survival after intensive care unit treatment for sepsis: A cohort study

OBJECTIVE

To determine the effect of sex on sepsis-related ICU admission and survival for up to 3-years.

METHODS

Retrospective cohort study of adults admitted to Australian ICUs between 2018 and 2020. Men and women with a primary diagnosis of sepsis were included. The primary outcome of time to death for up to 3-years was examined using Kaplan Meier plots. Secondary outcomes included the duration of ICU and hospital stay.

RESULTS

Of 523,576 admissions, there were 63,039 (12·0%) sepsis-related ICU admissions. Of these, there were 50,956 patients (43·4% women) with 3-year survival data. Men were older (mean age 66·5 vs 63·6 years), more commonly received mechanical ventilation (27·4% vs 24·7%) and renal replacement therapy (8·2% vs 6·8%) and had worse survival (Hazard Ratio [HR] 1·11; 95% Confidence Interval [CI] 1·07 to 1·14, P<0·001) compared to women. The duration of hospital and ICU stay was longer for men, compared to women (median hospital stay, 9.8 vs 9.4 days; p<0.001 and ICU stay, 2.7 vs 2.6 days; p<0.001).

CONCLUSION

Men are more likely to be admitted to ICU with sepsis and have worse survival for up to 3-years. Understanding causal mechanisms of sex differences may facilitate the development of targeted sepsis strategies.

Sex differences in cardiovascular response to sepsis

Recently, there has been increased recognition of the importance of sex as a biological factor affecting disease and health. Many preclinical studies have suggested that males may experience a less favorable outcome in response to sepsis than females. The underlying mechanisms for these differences are still largely unknown but are thought to be related to the beneficial effects of estrogen. Furthermore, the immunosuppressive role of testosterone is also thought to contribute to the sex-dependent differences that are present in clinical sepsis. There are still significant knowledge gaps in this field. This mini-review will provide a brief overview of sex-dependent variables in relation to sepsis and the cardiovascular system. Preclinical animal models for sepsis research will also be discussed. The intent of this mini-review is to inspire interest for future considerations of sex-related variables in sepsis that should be addressed to increase our understanding of the underlying mechanisms in sepsis-induced cardiovascular dysfunction for the identification of therapeutic targets and improved sepsis management and treatment.

Sex-related differences in the response of anti-platelet drug therapies targeting purinergic signaling pathways in sepsis

Sepsis, a complex clinical syndrome resulting from a serious infection, is a major healthcare problem associated with high mortality. Sex-related differences in the immune response to sepsis have been proposed but the mechanism is still unknown. Purinergic signaling is a sex-specific regulatory mechanism in immune cell physiology. Our studies have shown that blocking the ADP-receptor P2Y12 but not P2Y1 receptor was protective in male mice during sepsis, but not female. We now hypothesize that there are sex-related differences in modulating P2Y12 or P2Y1 signaling pathways during sepsis. Male and female wild-type (WT), P2Y12 knock-out (KO), and P2Y1 KO mice underwent sham surgery or cecal ligation and puncture (CLP) to induce sepsis. The P2Y12 antagonist ticagrelor or the P2Y1 antagonist MRS2279 were administered intra-peritoneally after surgery to septic male and female mice. Blood, lungs and kidneys were collected 24 hours post-surgery. Sepsis-induced changes in platelet activation, secretion and platelet interaction with immune cells were measured by flow cytometry. Neutrophil infiltration in the lung and kidney was determined by a myeloperoxidase (MPO) colorimetric assay kit. Sepsis-induced platelet activation, secretion and aggregate formation were reduced in male CLP P2Y12 KO and in female CLP P2Y1 KO mice compared with their CLP WT counterpart. Sepsis-induced MPO activity was reduced in male CLP P2Y12 KO and CLP P2Y1 KO female mice. CLP males treated with ticagrelor or MRS2279 showed a decrease in sepsis-induced MPO levels in lung and kidneys, aggregate formation, and platelet activation as compared to untreated male CLP mice. There were no differences in platelet activation, aggregate formation, and neutrophil infiltration in lung and kidney between female CLP mice and female CLP mice treated with ticagrelor or MRS2279. In human T lymphocytes, blocking P2Y1 or P2Y12 alters cell growth and secretion in vitro in a sex-dependent manner, supporting the data obtained in mice. In conclusion, targeting purinergic signaling represents a promising therapy for sepsis but drug targeting purinergic signaling is sex-specific and needs to be investigated to determine sex-related targeted therapies in sepsis.

On the same page? A qualitative study protocol on collaboration in a multi-laboratory preclinical study

INTRODUCTION

Medical advancements are slow to reach the patient bedside due to issues with knowledge translation from preclinical studies. Multi-laboratory preclinical studies are a promising strategy for addressing the methodological deficiencies that weaken the translational impact of single laboratory findings. However, multi-laboratory preclinical studies are rare and difficult, requiring strong collaboration to plan and execute a shared protocol. In multiteam systems such as these, collaboration is enhanced when members have cohesive ways of thinking about their goals and how to achieve them-that is, when they have "shared mental models". In this research project, we will examine how members of Canada's first multi-laboratory preclinical study build shared mental models and collaborate in the execution of their study.

METHODS

Six independent labs in Canada will conduct a preclinical study using a common protocol. To investigate mental models and collaboration in this multiteam system we will conduct a longitudinal qualitative study involving interviews at four time points, team observation, and document analysis. We will analyze interview transcripts using deductive coding to produce a matrix analysis of mental model content over time and inductive coding to produce a thematic analysis of members' experiences of collaboration over time. We will also triangulate data sources to "tell the story" of teamwork, capturing events and contextual information that explain changes in mental models and collaboration over time.

DISCUSSION

This study will be one of the most comprehensive longitudinal analyses of a real-world multiteam system, and the first within a preclinical laboratory setting. The results will contribute to our understanding of collaboration in multiteam systems, an organizational form increasingly used to tackle complex scientific and social problems. The results will also inform the implementation of future multi-laboratory preclinical studies, enhancing the likelihood of effective collaboration and improved 'bench to bedside' translation.

Analysis of trends in sepsis mortality in Brazil and by regions from 2010 to 2019

OBJECTIVE

To characterize the profile of inpatients and trend of sepsis mortality in the Brazilian Unified Health System (SUS), throughout Brazil, and in its regions separately, from 2010 to 2019.

METHODS

Observational, analytical and retrospective study of secondary data obtained through consultation to the Sistema de Informação Hospitalar (Hospital Information System). All incoming septicemia notifications from January 1, 2010 to December 31, 2019 were included. The following sociodemographic variables were used: sex, age, race, region and federative unit of residence. For data analysis, we used mortality and hospitalization coefficient, relative risk and Joinpoint regression.

RESULTS

There were a total of 1,044,227 cases of sepsis in Brazil, yielding a mean prevalence coefficient of 51.3/100 thousand inhabitants. There were 463,000 deaths from sepsis recorded, with a mean prevalence coefficient of 22.8 deaths/100,000 inhabitants. The highest rates occurred among the elderly, of brown race, and there was no significant difference between genders. The Southeast region accounted for the highest rates of hospitalization and deaths. A general trend toward increased mortality was observed in the period studied.

CONCLUSION

The heterogeneity of Brazil should be considered regarding socioeconomic and demographic characteristics, and differences in health investment and underreporting between regions, in order to understand the disease’s epidemiological course. Finally, these findings should be correlated with other studies, in an effort to understand the behavior of the disease, and provide inputs for public and private policies in order to reduce the expressiveness of cases and deaths from sepsis in Brazil.

Genetic background influences survival of infections with Salmonella enterica serovar Typhimurium in the Collaborative Cross

Salmonella infections typically cause self-limiting gastroenteritis, but in some individuals these bacteria can spread systemically and cause disseminated disease. Salmonella Typhimurium (STm), which causes severe systemic disease in most inbred mice, has been used as a model for disseminated disease. To screen for new infection phenotypes across a range of host genetics, we orally infected 32 Collaborative Cross (CC) mouse strains with STm and monitored their disease progression for seven days by telemetry. Our data revealed a broad range of phenotypes across CC strains in many parameters including survival, bacterial colonization, tissue damage, complete blood counts (CBC), and serum cytokines. Eighteen CC strains survived to day 7, while fourteen susceptible strains succumbed to infection before day 7. Several CC strains had sex differences in survival and colonization. Surviving strains had lower pre-infection baseline temperatures and were less active during their daily active period. Core body temperature disruptions were detected earlier after STm infection than activity disruptions, making temperature a better detector of illness. All CC strains had STm in spleen and liver, but susceptible strains were more highly colonized. Tissue damage was weakly negatively correlated to survival. We identified loci associated with survival on Chromosomes (Chr) 1, 2, 4, 7. Polymorphisms in Ncf2 and Slc11a1, known to reduce survival in mice after STm infections, are located in the Chr 1 interval, and the Chr 7 association overlaps with a previously identified QTL peak called Ses2. We identified two new genetic regions on Chr 2 and 4 associated with susceptibility to STm infection. Our data reveal the diversity of responses to STm infection across a range of host genetics and identified new candidate regions for survival of STm infection.

Sex Differences in Treatment of Adult Intensive Care Patients: A Systematic Review and Meta-Analysis

OBJECTIVES

To evaluate and synthesize the available literature on sex differences in the treatment of adult ICU patients.

DATA SOURCES

MEDLINE and EMBASE.

STUDY SELECTION

Two reviewers independently screened publications to identify observational studies of adult ICU patients that explicitly examined the association between sex and ICU treatment-specifically, mechanical ventilation, renal replacement therapy, and length of stay.

DATA EXTRACTION

We extracted data independently and in duplicate: mean age, illness severity, use of mechanical ventilation and renal replacement therapy, and length of stay in ICU and hospital. We assessed risk of bias using the Newcastle-Ottawa Scale. We used a DerSimonian-Laird random-effects model to calculate pooled odds ratios (ORs) and mean differences between women and men.

DATA SYNTHESIS

We screened 4,098 publications, identifying 21 eligible studies with 545,538 participants (42.7% women). The study populations ranged from 246 to 261,255 participants (median 4,420). Most studies (76.2%) were at high risk of bias in at least one domain, most commonly representativeness or comparability. Women were less likely than men to receive invasive mechanical ventilation (OR, 0.83; 95% CI, 0.77-0.89; I2 = 90.4%) or renal replacement therapy (OR, 0.79; 95% CI, 0.70-0.90; I2 = 76.2%). ICU length of stay was shorter in women than men (mean difference, -0.24 d; 95% CI, -0.37 to -0.12; I2 = 89.9%). These findings persisted in meta-analysis of data adjusted for illness severity and other confounders and also in sensitivity analysis excluding studies at high risk of bias. There was no significant sex difference in duration of mechanical ventilation or hospital length of stay.

CONCLUSIONS

Women were less likely than men to receive mechanical ventilation or renal replacement therapy and had shorter ICU length of stay than men. There is substantial heterogeneity and risk of bias in the literature; however, these findings persisted in sensitivity analyses.

Nurse bias and nursing care disparities related to patient characteristics: A scoping review of the quantitative and qualitative evidence

INTRODUCTION

Investigations of healthcare workers' implicit attitudes about patient characteristics and differences in delivery of healthcare due to bias are increasingly common. However, there is a gap in our understanding of nurse-specific bias and care disparities.

AIMS

To identify (a) the types of available evidence, (b) key factors and relationships identified in the evidence and (c) knowledge gaps related to nurse bias (nurse attitudes or beliefs towards a patient characteristic) and nursing care disparities (healthcare disparities related specifically to nursing care).

METHODS

Authors completed a scoping review using the Joanne Briggs Institute method and PRISMA-SCR checklist. Five databases were searched. After screening, 215 research reports were included and examined. Data were extracted from research reports and assessed for thematic patterns and trends across multiple characteristics.

RESULTS

Nurse bias and/or care disparity investigations have become increasingly common over the 38-year span of included reports. Multiple patient characteristics have been investigated, with the most common being race and/or ethnicity, gender and age. Twenty-nine of 215 studies identified a potential relationship between nurse bias regarding a characteristic and nursing care of individuals with that characteristic. Of these studies, 27 suggested the bias was associated with a negative disparate impact on nursing care. Only 12 reports included evaluating an intervention designed to reduce nurse bias or nursing care-related healthcare disparities.

CONCLUSIONS

Despite increasing research focus on individual bias and disparities in healthcare, the accumulated knowledge regarding nurses has not significantly advanced past a descriptive, exploratory level. Nor has there been a consistent focus on the role of nurses, who represent the largest component of the professional healthcare workforce.

RELEVANCE TO CLINICAL PRACTICE

National and international codes of ethics for nurses require provision of care according to individual, unique patient need, disregarding bias and incorporating patient characteristics into their plan of care.

Sex as a prognostic factor for mortality in critically ill adults with sepsis: a systematic review and meta-analysis

OBJECTIVE

To assess the role of sex as an independent prognostic factor for mortality in patients with sepsis admitted to intensive care units (ICUs).

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

MEDLINE, Embase, Web of Science, ClinicalTrials.gov and the WHO Clinical Trials Registry from inception to 17 July 2020.

STUDY SELECTION

Studies evaluating independent associations between sex and mortality in critically ill adults with sepsis controlling for at least one of five core covariate domains prespecified following a literature search and consensus among experts.

DATA EXTRACTION AND SYNTHESIS

Two authors independently extracted and assessed the risk of bias using Quality In Prognosis Studies tool. Meta-analysis was performed by pooling adjusted estimates. The Grades of Recommendations, Assessment, Development and Evaluation approach was used to rate the certainty of evidence.

RESULTS

From 14 304 records, 13 studies (80 520 participants) were included. Meta-analysis did not find sex-based differences in all-cause hospital mortality (OR 1.02, 95% CI 0.79 to 1.32; very low-certainty evidence) and all-cause ICU mortality (OR 1.19, 95% CI 0.79 to 1.78; very low-certainty evidence). However, females presented higher 28-day all-cause mortality (OR 1.18, 95% CI 1.05 to 1.32; very low-certainty evidence) and lower 1-year all-cause mortality (OR 0.83, 95% CI 0.68 to 0.98; low-certainty evidence). There was a moderate risk of bias in the domain adjustment for other prognostic factors in six studies, and the certainty of evidence was further affected by inconsistency and imprecision.

CONCLUSION

The prognostic independent effect of sex on all-cause hospital mortality, 28-day all-cause mortality and all-cause ICU mortality for critically ill adults with sepsis was uncertain. Female sex may be associated with decreased 1-year all-cause mortality.

PROSPERO REGISTRATION NUMBER

CRD42019145054.

Serum Perilipin 2 (PLIN2) Predicts Multiple Organ Dysfunction in Critically Ill Patients

Perilipin 2 (PLIN2) is a lipid droplet protein with various metabolic functions. However, studies investigating PLIN2 in the context of inflammation, especially in systemic and acute inflammation, are lacking. Hence, we assessed the relevance of serum PLIN2 in critically ill patients. We measured serum PLIN2 serum in 259 critically ill patients (166 with sepsis) upon admission to a medical intensive care unit (ICU) compared to 12 healthy controls. A subset of 36 patients underwent computed tomography to quantify body composition. Compared to controls, serum PLIN2 concentrations were elevated in critically ill patients at ICU admission. Interestingly, PLIN2 independently indicated multiple organ dysfunction (MOD), defined as a SOFA score > 9 points, at ICU admission, and was also able to independently predict MOD after 48 h. Moreover, serum PLIN2 levels were associated with severe respiratory failure potentially reflecting a moribund state. However, PLIN2 was neither a predictor of ICU mortality nor did it reflect metabolic dysregulation. Conclusively, the first study assessing serum PLIN2 in critical illness proved that it may assist in risk stratification because it is capable of independently indicating MOD at admission and predicting MOD 48 h after PLIN2 measurement. Further evaluation regarding the underlying mechanisms is warranted.

Sex- and Gender-Dependent Differences in Clinical and Preclinical Sepsis

ABSTRACT

In this mini-review we provide an overview of sex- and gender-dependent issues in both clinical and preclinical sepsis. The increasing recognition for the need to account for sex and gender in biomedical research brings a unique set of challenges and requires researchers to adopt best practices when conducting and communicating sex- and gender-based research. This may be of particular importance in sepsis, given the potential contribution of sex bias in the failures of translational sepsis research in adults and neonates. Clinical evidence of sex-dependent differences in sepsis is equivocal. Since clinical studies are limited to observational data and confounded by a multitude of factors, preclinical studies provide a unique opportunity to investigate sex differences in a controlled, experimental environment. Numerous preclinical studies have suggested that females may experience favorable outcomes in comparison with males. The underlying mechanistic evidence for sex-dependent differences in sepsis and other models of shock (e.g., trauma-hemorrhage) largely centers around the beneficial effects of estrogen. Other mechanisms such as the immunosuppressive role of testosterone and X-linked mosaicism are also thought to contribute to observed sex- and gender-dependent differences in sepsis. Significant knowledge gaps still exist in this field. Future investigations can address these gaps through careful consideration of sex and gender in clinical studies, and the use of clinically accurate preclinical models that reflect sex differences. A better understanding of sex-and gender-dependent differences may serve to increase translational research success.

The Effects of Biological Sex on Sepsis Treatments in Animal Models: A Systematic Review and a Narrative Elaboration on Sex- and Gender-Dependent Differences in Sepsis

Preclinical studies provide an opportunity to evaluate the relationship between sex and sepsis, and investigate underlying mechanisms in a controlled experimental environment. The objective of our systematic review was to assess the impact of biological sex on treatment response to fluid and antibiotic therapy in animal models of sepsis. Furthermore, we provide a narrative elaboration of sex-dependent differences in preclinical models of sepsis.

DATA SOURCES

MEDLINE and Embase were searched from inception to March 16, 2020.

STUDY SELECTION

All studies reporting sex-stratified data comparing antibiotics and/or fluid resuscitation with a placebo or no treatment arm in an in vivo model of sepsis were included.

DATA EXTRACTION

Outcomes of interest were mortality (primary) and organ dysfunction (secondary). Risk of bias was assessed. Study selection and data extraction were conducted independently and in duplicate.

DATA SYNTHESIS

The systematic search returned 2,649 unique studies, and two met inclusion criteria. Both studies used cecal ligation and puncture models with imipenem/cilastatin antibiotics. No eligible studies investigated fluids. In one study, antibiotic therapy significantly reduced mortality in male, but not female, animals. The other study reported no sex differences in organ dysfunction. Both studies were deemed to be at a high overall risk of bias.

CONCLUSIONS

There is a remarkable and concerning paucity of data investigating sex-dependent differences in fluid and antibiotic therapy for the treatment of sepsis in animal models. This may reflect poor awareness of the importance of investigating sex-dependent differences. Our discussion therefore expands on general concepts of sex and gender in biomedical research and sex-dependent differences in key areas of sepsis research such as the cardiovascular system, immunometabolism, the microbiome, and epigenetics. Finally, we discuss current clinical knowledge, the potential for reverse translation, and directions for future studies.

REGISTRATION

PROSPERO CRD42020192738.

De Ritis Ratio as a Significant Prognostic Factor in Patients with Sepsis: A Retrospective Analysis

PURPOSE

This study was performed to investigate the relationship between the aspartate transaminase and/or alanine transaminase ratio (DRR) and long-term mortality of patients diagnosed with sepsis or septic shock.

MATERIALS AND METHODS

We conducted a retrospective study among adult septic patients who were admitted to the surgical intensive care unit (ICU) of the Chinese People's Liberation Army (PLA) General Hospital from January 2014 to December 2018. Baseline characteristics were compared between survivors and non survivors. We performed univariate and multivariate Cox regression analyses to evaluate the relation of DRR with 180-day mortality. The potential prognostic value of DRR in predicting mortality rate was assessed by receiver operating characteristic (ROC) curve analysis. In addition, we conducted subgroup analysis by the optimal DRR cutoff value.

RESULTS

We included a total of 183 patients in the current study, and 44 (24%) patients died within 180 days of hospitalization. Univariate and multivariate Cox analyses revealed that DRR was an independent predictor of 180-day mortality (hazard ratio [HR] 1.421, 95% confidence interval [CI] 1.073-1.883, P = 0.014). The predictive accuracy of DRR for 180-day mortality was presented as an ROC curve, which had an area under the curve (AUC) of 0.708 (95% CI 0.629-0.786, P < 0.001). After we stratified all enrolled patients into two groups by using the optimal cutoff value of 1.29, we observed a significantly higher mortality in patients with a relatively high DRR.

CONCLUSIONS

An elevated DRR was associated with higher 180-day mortality among septic patients, and DRR might be an optimal marker for predicting the long-term mortality of sepsis. More prospective and randomized trials are needed to confirm the prognostic value of DRR.

17β-Estradiol Promotes Trained Immunity in Females Against Sepsis via Regulating Nucleus Translocation of RelB

Sepsis is more common among males than females, and the unequal estrogen levels have been suspected to play a vital role in gender differences. Recently, trained immunity is reported to be a novel strategy for the innate immune system to fight infection. However, it has not been clarified whether β-glucan-induced trained immunity causes different responses to early sepsis between male and female mice. In this study, sepsis was induced in mice by intraperitoneal injection of Escherichia coli (E. coli). The changes of inflammatory cytokines expression, and macrophage polarization in male, female, and ovariectomized C57BL/6 mice in sepsis model were investigated. For in vitro studies, different macrophages were treated with LPS. The function of estradiol (E2) on macrophage cell lines was verified and the mechanism of E2 affecting trained immunity was explored. We demonstrated that β-glucan-induced trained immunity was more resistant to sepsis in female than male mice. Macrophage polarization toward the M1 phenotype, which exhibited enhanced trained immunity, was related to the difference in sepsis resistance between female and male mice. Moreover, ovariectomized (OVX) mice manifested serious sepsis consequences with a weaker trained immunity effect than female mice. Female bone marrow-derived macrophages (BMDMs) were also apt to be polarized to the M1 phenotype in response to trained immunity in vitro. Furthermore, E2 promoted trained immunity in macrophage cell lines J774 and RAW264.7. E2 was also verified to facilitate trained immunity in primary BMDMs from female and male mice. Mechanistically, we found that E2 inhibited the nuclear translocation of RelB, which is a member of non-canonical pathway of NFκB and contributes to macrophage polarization to change the intensity of trained immunity. This study is the first to indicate the role of E2 in the trained immunity induced by β-glucan to protect against E. coli-induced sepsis via the non-canonical NFκB pathway. These results improve our understanding of the molecular mechanisms governing trained immunity in gender differences.

Gender differences in mortality and quality of life after septic shock: A post-hoc analysis of the ARISE study

PURPOSE

To assess the impact of gender and pre-menopausal state on short- and long-term outcomes in patients with septic shock.

MATERIAL AND METHODS

Cohort study of the Australasian Resuscitation in Sepsis Evaluation (ARISE) trial, an international randomized controlled trial comparing early goal-directed therapy (EGDT) to usual care in patients with early septic shock, conducted between October 2008 and April 2014. The primary exposure in this analysis was legal gender and the secondary exposure was pre-menopausal state defined by chronological age (≤ 50 years).

RESULTS

641 (40.3%) of all 1591 ARISE trial participants in the intention-to-treat population were females and overall, 337 (21.2%) (146 females) patients were 50  years of age or younger. After risk-adjustment, we could not identify any survival benefit for female patients at day 90 in the younger (≤50 years) (adjusted Odds Ratio (aOR): 0.91 (0.46-1.89), p = .85) nor in the older (>50 years) age-group (aOR: 1.10 (0.81-1.49), p = .56). Similarly, there was no gender-difference in ICU, hospital, 1-year mortality nor quality of life measures.

CONCLUSIONS

This post-hoc analysis of a large multi-center trial in early septic shock has shown no short- or long-term survival effect for women overall as well as in the pre-menopausal age-group.

Does Gender Matter in Septic Patient Outcomes?

PURPOSE

The purpose of this study was to examine potential gender disparities in relation to factors associated with sepsis management among a cohort of patients admitted through an emergency department with a discharge diagnosis of severe sepsis or septic shock. Sepsis is one of the leading causes of death globally, with significant associated costs. Predictors of survival for those with sepsis-related diagnoses are complex.

DESIGN AND METHODS

The study had a retrospective, descriptive cross-sectional design. The sample (N = 482) included patients 18 years of age or older who presented to the emergency department of a nonprofit, Magnet-recognized, acute care hospital located in southern California. Subjects included those who subsequently met the criteria for a discharge diagnosis of severe sepsis or septic shock as defined by the Surviving Sepsis Campaign. Patient characteristics, clinical variables, care management processes, and outcomes were extracted from the electronic health record. A multivariate model was analyzed.

FINDINGS

The sample included 234 women (48.5%) and 248 men (51.5%). Logistic regression with eight independent variables (discharge diagnosis, age, comorbidities, length of hospital stay, source of infection, first serum lactate level measured, recommended fluids administered, and gender) reliably predicted odds for patient survival, ϰ² (12) = 118.38, p < .001, and correctly classified 77.3% of cases. All eight independent variables significantly contributed to the model. Men had a higher likelihood of hospital survival than women (odds ratio 1.68; 95% confidence interval 1.01-2.79; p = .045).

CONCLUSIONS

The Surviving Sepsis Campaign has provided a clear pathway for care of patients with sepsis-related diagnoses. Therapeutic strategies should be developed to address differences in outcome by gender. The adoption of more aggressive applications of evidence-based interventions for these patients may result in better patient outcomes.

CLINICAL RELEVANCE

Providers should understand the importance of adhering to sepsis protocols, minimizing treatment disparities, and recognizing gender differences.

Gender differences in trauma, shock and sepsis

Despite efforts in prevention and intensive care, trauma and subsequent sepsis are still associated with a high mortality rate. Traumatic injury remains the main cause of death in people younger than 45 years and is thus a source of immense social and economic burden. In recent years, the knowledge concerning gender medicine has continuously increased. A number of studies have reported gender dimorphism in terms of response to trauma, shock and sepsis. However, the advantageous outcome following trauma-hemorrhage in females is not due only to sex. Rather, it is due to the prevailing hormonal milieu of the victim. In this respect, various experimental and clinical studies have demonstrated beneficial effects of estrogen for the central nervous system, the cardiopulmonary system, the liver, the kidneys, the immune system, and for the overall survival of the host. Nonetheless, there remains a gap between the bench and the bedside. This is most likely because clinical studies have not accounted for the estrus cycle. This review attempts to provide an overview of the current level of knowledge and highlights the most important organ systems responding to trauma, shock and sepsis. There continues to be a need for clinical studies on the prevailing hormonal milieu following trauma, shock and sepsis.

Sex and mortality in septic severe acute kidney injury

PURPOSE

To investigate the relationship between sex and mortality and whether menopause or the intensity of renal replacement therapy (RRT) modify this relationship in patients with severe septic acute kidney injury (AKI).

MATERIALS AND METHODS

Post-hoc analysis of patients with sepsis included in the Randomized Evaluation of Normal versus Augmented Level renal replacement therapy (RENAL) trial.

RESULTS

Of 724 patients, 458 (63.3%) were male and 266 (36.7%) were female. The mean delivered effluent flow rate was 25.6 ± 7.4 ml/kg/h (80 ± 15% of prescribed dose) in males and 27.4 ± 7.6 ml/kg/h (83 ± 15% of prescribed dose) in females (p = .01). A total of 237 (51.7%) males and 118 (44.5%) females died within 90 days of randomization (p = .06). The adjusted hazard ratio (HR) for 90-day mortality was significantly decreased in females as compared with males (HR 0.74, 95% CI 0.57 to 0.96, p = .02). The relationship between sex and mortality was not significantly altered by menopausal status (adjusted P value for interaction 0.99) or by RRT intensity allocation (adjusted P value for interaction 0.27).

CONCLUSIONS

In a cohort of patients with sepsis and severe AKI, female sex was associated with improved survival. The relationship between sex and survival was not altered by menopausal status or RRT intensity.

Female mice exhibit less renal mitochondrial injury but greater mortality using a comorbid model of experimental sepsis

Given the inherent heterogeneity of the septic patient population and possible comorbid conditions, it is not surprising that the influence of gender on incidence and outcomes are still unclear. The goal of this study was to use a clinically relevant murine model of sepsis, cecal ligation and puncture (CLP) in CD1 mice, with and without uniphrectomy as a comorbid condition to investigate possible gender differences in renal mitochondrial function and dynamics. High resolution respirometry on fresh kidney biopsies was used to measure renal respiratory complex activities. At 18h post-CLP with nephrectomy male mice showed significant reductions in complex I, II, and III activities, while females were less effected; only complex I was significantly reduced from sham mice. Taken together, our studies revealed, for the first time, gender differences in mitochondrial respiratory activity even in the absence of sepsis. We also examined expression of key mitochondrial fission and fusion proteins. In both genders and in both CLP models, protein expression of the primary fission protein, DRP1 was significantly decreased. No changes were observed in female mice in either CLP model; whereas, male mice demonstrated a slight reduction in MFN1 and the short form of OPA1 after CLP, and modest increase in MFN2 with CLP plus nephrectomy. In both genders CLP with nephrectomy produced a greater increase in serum blood urea nitrogen, a biomarker of renal injury, than without nephrectomy. However, CLP with nephrectomy produced significantly lower 96-hour survival in females. Our results suggest that the CLP nephrectomy comorbid model of sepsis may be an appropriate model to study gender differences a select group of predisposed individuals.

The Collaborative Cross mouse model for dissecting genetic susceptibility to infectious diseases

Infectious diseases, also known as communicable diseases, refer to a full range of maladies caused by pathogen invasion to the host body. Host response towards an infectious pathogen varies between individuals, and can be defined by responses from asymptomatic to lethal. Host response to infectious pathogens is considered as a complex trait controlled by gene-gene (host-pathogen) and gene-environment interactions, leading to the extensive phenotypic variations between individuals. With the advancement of the human genome mapping approaches and tools, various genome-wide association studies (GWAS) were performed, aimed at mapping the genetic basis underlying host susceptibility towards infectious pathogens. In parallel, immense efforts were invested in enhancing the genetic mapping resolution and gene-cloning efficacy, using advanced mouse models including advanced intercross lines; outbred populations; consomic, congenic; and recombinant inbred lines. Notwithstanding the evident advances achieved using these mouse models, the genetic diversity was low and quantitative trait loci (QTL) mapping resolution was inadequate. Consequently, the Collaborative Cross (CC) mouse model was established by full-reciprocal mating of eight divergent founder strains of mice (A/J, C57BL/6J, 129S1/SvImJ, NOD/LtJ, NZO/HiLtJ, CAST/Ei, PWK/PhJ, and WSB/EiJ) generating a next-generation mouse genetic reference population (CC lines). Presently, the CC mouse model population comprises a set of about 200 recombinant inbred CC lines exhibiting a unique high genetic diversity and which are accessible for multidisciplinary studies. The CC mouse model efficacy was validated by various studies in our lab and others, accomplishing high-resolution (< 1 MB) QTL genomic mapping for a variety of complex traits, using about 50 CC lines (3-4 mice per line). Herein, we present a number of studies demonstrating the power of the CC mouse model, which has been utilized in our lab for mapping the genetic basis of host susceptibility to various infectious pathogens. These include Aspergillus fumigatus, Klebsiella pneumoniae, Porphyromonas gingivalis and Fusobacterium nucleatum (causing oral mixed infection), Pseudomonas aeruginosa, and the bacterial toxins Lipopolysaccharide and Lipoteichoic acid.