Gender-Specific Effects on Immune Response and Cardiac Function after Trauma Hemorrhage and Sepsis

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.

Irisin Preserves Cardiac Performance and Insulin Sensitivity in Response to Hemorrhage

Irisin, a cleaved product of the fibronectin type III domain containing protein-5, is produced in the muscle tissue, which plays an important role in modulating insulin resistance. However, it remains unknown if irisin provides a protective effect against the detrimental outcomes of hemorrhage. Hemorrhages were simulated in male CD-1 mice to achieve a mean arterial blood pressure of 35–45 mmHg, followed by resuscitation. Irisin (50 ng/kg) and the vehicle (saline) were administrated at the start of resuscitation. Cardiac function was assessed by echocardiography, and hemodynamics were measured through femoral artery catheterization. A glucose tolerance test was used to evaluate insulin sensitivity. An enzyme-linked immunosorbent assay was performed to detect inflammatory factors in the muscles and blood serum. Western blot was carried out to assess the irisin production in skeletal muscles. Histological analyses were used to determine tissue damage and active-caspase 3 apoptotic signals. The hemorrhage suppressed cardiac performance, as indicated by a reduced ejection fraction and fractional shortening, which was accompanied by enhanced insulin resistance and hyperinsulinemia. Furthermore, the hemorrhage resulted in a marked decrease in irisin and an increase in the production of tumor necrosis factor-α (TNF-α) and interleukin-1 (IL-1). Additionally, the hemorrhage caused marked edema, inflammatory cell infiltration and active-caspase 3 positive signals in skeletal muscles and cardiac muscles. Irisin treatment led to a significant improvement in the cardiac function of animals exposed to a hemorrhage. In addition, irisin treatment improved insulin sensitivity, which is consistent with the suppressed inflammatory cytokine secretion elicited by hemorrhages. Furthermore, hemorrhage-induced tissue edema, inflammatory cell infiltration, and active-caspase 3 positive signaling were attenuated by irisin treatment. The results suggest that irisin protects against damage from a hemorrhage through the modulation of insulin sensitivity.

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.

Effects of different plasma expanders on rats subjected to severe acute normovolemic hemodilution

BACKGROUND

Plasma expanders are widely used for acute normovolemic hemodilution (ANH). However, existing studies have not focused on large-volume infusion with colloidal plasma expanders, and there is a lack of studies that compare the effects of different plasma expanders.

METHODS

The viscosity, hydrodynamic radius (R_h) and colloid osmotic pressure (COP) of plasma expanders were determined by a cone-plate viscometer, Zetasizer and cut-off membrane, respectively. Sixty male rats were randomized into five groups with Gelofusine (Gel), Hydroxyethyl Starch 200/0.5 (HES200), Hydroxyethyl Starch 130/0.4 (HES130), Hydroxyethyl Starch 40 (HES40), and Dextran40 (Dex40), with 12 rats used in each group to build the ANH model. ANH was performed by the withdrawal of blood and simultaneous infusion of plasma expanders. Acid-base, lactate, blood gas and physiological parameters were detected.

RESULTS

Gel had a lower intrinsic viscosity than HES200 and HES130 (P < 0.01), but at a low shear rate in a mixture of colloids, red cells and plasma, Gel had a higher viscosity (P < 0.05 or P < 0.01, respectively). For hydroxyethyl starch plasma expanders, the COP at a certain concentration decreases from 11.1 mmHg to 6.1 mmHg with the increase of R_h from 10.7 nm to 20.2 nm. A severe ANH model, with the hematocrit of 40% of the baseline level, was established and accompanied by disturbances in acid-base, lactate and blood gas parameters. At the end of ANH and 60 min afterward, the Dex40 group showed a worse outcome in maintaining the acid-base balance and systemic oxygenation compared to the other groups. The systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) decreased significantly in all groups at the end of ANH. The DBP and MAP in the Dex40 group further decreased 60 min after the end of ANH. During the process of ANH, the Dex40 group showed a drop and recovery in SBP, DBP and MAP. The DBP and MAP in the HES200 group were significantly higher than those in the other groups at some time points (P < 0.05 or P < 0.01).

CONCLUSION

Gel had a low intrinsic viscosity but may increase the whole blood viscosity at low shear rates. R_h and COP showed a strong correlation among hydroxyethyl starch plasma expanders. Dex40 showed a worse outcome in maintaining the acid-base balance and systemic oxygenation compared to the other plasma expanders. During the process of ANH, Dex40 displayed a V-shaped recovery pattern for blood pressure, and HES200 had the advantage in sustaining the DBP and MAP at some time points.

Sex differences in non-obstructive coronary artery disease

Ischaemic heart disease is a leading cause of morbidity and mortality in both women and men. Compared with men, symptomatic women who are suspected of having myocardial ischaemia are more likely to have no obstructive coronary artery disease (CAD) on coronary angiography. Coronary vasomotor disorders and coronary microvascular dysfunction (CMD) have been increasingly recognized as important contributors to angina and adverse outcomes in patients with no obstructive CAD. CMD from functional and structural abnormalities in the microvasculature is associated with adverse cardiac events and mortality in both sexes. Women may be particularly susceptible to vasomotor disorders and CMD due to unique factors such as inflammation, mental stress, autonomic, and neuroendocrine dysfunction, which predispose to endothelial dysfunction and CMD. CMD can be detected with coronary reactivity testing and non-invasive imaging modalities; however, it remains underdiagnosed. This review focuses on sex differences in presentation, pathophysiologic risk factors, diagnostic testing, and prognosis of CMD.

Polymorphisms of IRAK1 Gene on X Chromosome Is Associated with Hashimoto Thyroiditis in Korean Children

Autoimmune thyroid disease (AITD) is predominant in females and has been focused on the sexual diploid in immune response. The IL-1 receptor-associated kinase 1 (IRAK1) gene on the X chromosome was recently suggested as strong autoimmune disease-susceptible loci, second to the major histocompatibility complex region. We investigated the frequency of IRAK1 single-nucleotide polymorphisms (SNPs) in children with AITD. In this study, we observed that SNPs of IRAK1 including rs3027898, rs1059703, and rs1059702 in 115 Korean AITD pediatric patients (Graves' disease = 74 [females = 52/males = 22]; Hashimoto disease [HD] = 41 [females = 38/males = 3]; thyroid-associated ophthalmopathy [TAO] = 40 (females = 27/males = 13); without TAO = 75 (females = 63/males = 12); total males = 25, total females = 90; mean age = 11.9 years) and 204 healthy Korean individuals (males = 104/females = 100). The data from cases and controls were analyzed from separate sex-stratified or all combined by χ 2 test for categorical variables and Student t test for numerical variables. Our study revealed that SNPs of IRAK1-associated HD and without TAO but Graves' disease and TAO were not found significant. When cases and controls were analyzed by separate sex, we found that rs3027898 AA, rs1059703 AA, and rs1059702 GG showed disease susceptibility in female AITD, HD, and without TAO. Also, all rs3027898, rs1059703, and rs1059702 were found to be in strong linkage disequilibrium (D' = 0.96-0.98, r2 = 0.83-0.97). The haplotype of 3 SNPs was higher in AITD than in controls (CGA, r2 = 5.42, P = 0.019). Our results suggest that IRAK1 polymorphisms may contribute to the pathogenesis of HD, AITD, and without thyroid-associated ophthalmopathy for females.

A Combination Treatment Strategy for Hemorrhagic Shock in a Rat Model Modulates Autophagy

Hemorrhagic shock leads to whole body hypoxia and nutrient deprivation resulting in organ dysfunction and mortality. Previous studies demonstrated that resveratrol, dichloroacetate, and niacin improve organ function and survival in rats following hemorrhagic shock injury (HI). We hypothesized that a combinatorial formula that collectively promotes survival will decrease the dose of individual compounds toward effective therapy for HI. Sprague-Dawley rats were subjected to HI by withdrawing 60% blood volume. NiDaR (Niacin-Dichloroacetate-Resveratrol; 2 mg/kg dose of each) or vehicle was administered following the shock in the absence of fluid resuscitation, and survival monitored. In order to study alterations in molecular mediators, separate groups of rats were administered NiDaR or vehicle along with resuscitation fluid, following HI. We observed significant improvement (p < 0.05) in survival following HI in animals that received NiDaR, in the absence of fluid resuscitation. In NiDaR treated animals that received resuscitation fluid, MAP was significantly increased compared to Veh-treated rats. HI-induced increase in systemic IL-6 levels and tissue expression of IL-6, IL-10, IL-1β, and IL-18 genes in the heart were attenuated with NiDaR treatment. NiDaR promoted autophagy following HI as demonstrated by reduced p-mTOR, increased p-ULK1 and p-Beclin. The combinatorial formula, NiDaR, reduced inflammation, promoted autophagy, and reduced doses of individual compounds used, and may be more effective in genetically heterogeneous population. In conclusion our experiments demonstrated that the combinatorial drug treatment has salutary effect in rats following HI.

Racial Differences in Immunological Landscape Modifiers Contributing to Disparity in Prostate Cancer

Prostate cancer affects African Americans disproportionately by exhibiting greater incidence, rapid disease progression, and higher mortality when compared to their Caucasian counterparts. Additionally, standard treatment interventions do not achieve similar outcome in African Americans compared to Caucasian Americans, indicating differences in host factors contributing to racial disparity. African Americans have allelic variants and hyper-expression of genes that often lead to an immunosuppressive tumor microenvironment, possibly contributing to more aggressive tumors and poorer disease and therapeutic outcomes than Caucasians. In this review, we have discussed race-specific differences in external factors impacting internal milieu, which modify immunological topography as well as contribute to disparity in prostate cancer.

Impact of Sexual Dimorphism on Trauma Patterns and Clinical Outcomes of Patients with a High-Risk Score of the Osteoporosis Self-Assessment Tool for Asians: A Propensity Score-Matched Analysis

The Osteoporosis Self-assessment Tool for Asians (OSTA) is a validated index based on age and weight to predict the risk of osteoporosis in women. This cross-sectional study was designed to evaluate the impact of sexual dimorphism on the trauma patterns and the clinical outcomes of patients with high-risk OSTA scores. Trauma data of patients with high-risk OSTA scores between 1 January 2009 and 31 December 2015 were retrieved from the trauma registry system of a level I trauma center. A total of 2248 patients including 1585 women and 663 men were included in this study. In-hospital mortality was assessed as the primary outcome in the propensity score-matched analyses of the female and male patients, which were created in a 1:1 ratio under the adjustment of potential confounders, including age, co-morbidity, mechanism and injury-severity score (ISS). Female patients with a high-risk OSTA score had significantly lower mortality rates than their male counterparts. Among the propensity score-matched population, female patients had lower odds of having cerebral contusion and pneumothorax, but higher odds of presenting with radial, ulnar and femoral fractures than male patients. In addition, the female patients still had significantly lower odds of mortality (odds ratio (OR), 0.5; 95% confidence interval (CI), 0.29-0.90; p = 0.019) than the male patients. However, no significant differences were noted in the length of stay (LOS) in hospital, intensive-care unit (ICU) admission, and LOS in the ICU between the sexes. Female patients with high-risk OSTA scores showed different injury patterns and significantly lower mortality rates than their male counterparts, even after controlling for potential confounding factors.

Thioredoxin-1 attenuates sepsis-induced cardiomyopathy after cecal ligation and puncture in mice

BACKGROUND

Sepsis is a leading cause of mortality among patients in intensive care units across the USA. Thioredoxin-1 (Trx-1) is an essential 12 kDa cytosolic protein that, apart from maintaining the cellular redox state, possesses multifunctional properties. In this study, we explored the possibility of controlling adverse myocardial depression by overexpression of Trx-1 in a mouse model of severe sepsis.

METHODS

Adult C57BL/6J and Trx-1Tg/+ mice were divided into wild-type sham (WTS), wild-type cecal ligation and puncture (WTCLP), Trx-1Tg/+sham (Trx-1Tg/+S), and Trx-1Tg/+CLP groups. Cardiac function was evaluated before surgery, 6 and 24 hours after CLP surgery. Immunohistochemical and Western blot analysis were performed after 24 hours in heart tissue sections.

RESULTS

Echocardiography analysis showed preserved cardiac function in the Trx-1Tg/+ CLP group compared with the WTCLP group. Similarly, Western blot analysis revealed increased expression of Trx-1, heme oxygenase-1 (HO-1), survivin (an inhibitor of apoptosis [IAP] protein family), and decreased expression of thioredoxin-interacting protein (TXNIP), caspase-3, and 3- nitrotyrosine in the Trx-1Tg/+CLP group compared with the WTCLP group. Immunohistochemical analysis showed reduced 4-hydroxynonenal, apoptosis, and vascular leakage in the cardiac tissue of Trx-1Tg/+CLP mice compared with mice in the WTCLP group.

CONCLUSIONS

Our results indicate that overexpression of Trx-1 attenuates cardiac dysfunction during CLP. The mechanism of action may involve reduction of oxidative stress, apoptosis, and vascular permeability through activation of Trx-1/HO-1 and anti-apoptotic protein survivin.

Modulating the Biologic Activity of Mesenteric Lymph after Traumatic Shock Decreases Systemic Inflammation and End Organ Injury

Introduction

Trauma/hemorrhagic shock (T/HS) causes the release of pro-inflammatory mediators into the mesenteric lymph (ML), triggering a systemic inflammatory response and acute lung injury (ALI). Direct and pharmacologic vagal nerve stimulation prevents gut barrier failure and alters the biologic activity of ML after injury. We hypothesize that treatment with a pharmacologic vagal agonist after T/HS would attenuate the biologic activity of ML and prevent ALI.

Methods

ML was collected from male Sprague-Dawley rats after T/HS, trauma-sham shock (T/SS) or T/HS with administration of the pharmacologic vagal agonist CPSI-121. ML samples from each experimental group were injected into naïve mice to assess biologic activity. Blood samples were analyzed for changes in STAT3 phosphorylation (pSTAT3). Lung injury was characterized by histology, permeability and immune cell recruitment.

Results

T/HS lymph injected in naïve mice caused a systemic inflammatory response characterized by hypotension and increased circulating monocyte pSTAT3 activity. Injection of T/HS lymph also resulted in ALI, confirmed by histology, lung permeability and increased recruitment of pulmonary macrophages and neutrophils to lung parenchyma. CPSI-121 attenuated T/HS lymph-induced systemic inflammatory response and ALI with stable hemodynamics and similar monocyte pSTAT3 levels, lung histology, lung permeability and lung immune cell recruitment compared to animals injected with lymph from T/SS.

Conclusion

Treatment with CPSI-121 after T/HS attenuated the biologic activity of the ML and decreased ALI. Given the superior clinical feasibility of utilizing a pharmacologic approach to vagal nerve stimulation, CPSI-121 is a potential treatment strategy to limit end organ dysfunction after injury.

X-Linked miRNAs Associated with Gender Differences in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease that predominantly affects women. MicroRNAs have emerged as crucial regulators of the immune system, whose expression is deregulated in RA. We aimed at quantifying the expression level of 14 miRNAs located on the X chromosome and at identifying whether differences are associated with disease and/or sex. A case-control study of 21 RA patients and 22 age- and sex-matched healthy controls was performed on peripheral blood mononuclear cells. The expression level of five miRNAs (miR-221, miR-222, miR-532, miR-106a, and miR-98) was significantly different between RA and controls when stratifying by sex, and the expression level of four miRNAs (miR-222, miR-532, miR-98, and miR-92a) was significantly different between RA females and males. The expression quantitative trait loci (eQTL) analysis revealed a significant gender effect of the FoxP3 promoter polymorphism rs3761548A/C on miR-221, miR-222 and miR-532 expression levels, and of the FoxP3 polymorphism rs2232365A/G on miR-221 expression levels in PBMC of RA patients. These data further support the involvement of the X chromosome in RA susceptibility. X-linked miRNAs, in the context of sex differences, might provide novel insight into new molecular mechanisms and potential therapeutic targets in RA for disease treatment and prevention.

Interactions between inflammation, sex steroids, and Alzheimer's disease risk factors

Alzheimer's disease (AD) is an age-related neurodegenerative disorder for which there are no effective strategies to prevent or slow its progression. Because AD is multifactorial, recent research has focused on understanding interactions among the numerous risk factors and mechanisms underlying the disease. One mechanism through which several risk factors may be acting is inflammation. AD is characterized by chronic inflammation that is observed before clinical onset of dementia. Several genetic and environmental risk factors for AD increase inflammation, including apolipoprotein E4, obesity, and air pollution. Additionally, sex steroid hormones appear to contribute to AD risk, with age-related losses of estrogens in women and androgens in men associated with increased risk. Importantly, sex steroid hormones have anti-inflammatory actions and can interact with several other AD risk factors. This review examines the individual and interactive roles of inflammation and sex steroid hormones in AD, as well as their relationships with the AD risk factors apolipoprotein E4, obesity, and air pollution.