Mechanisms and consequences of sex differences in immune responses

Acute exercise boosts NAD+ metabolism of human peripheral blood mononuclear cells

Nicotinamide adenine dinucleotide (NAD+) coenzymes are the central electron carriers in biological energy metabolism. Low NAD+ levels are proposed as a hallmark of ageing and several diseases, which has given rise to therapeutic strategies that aim to tackle these conditions by boosting NAD+ levels. As a lifestyle factor with preventive and therapeutic effects, exercise increases NAD+ levels across various tissues, but so far human trials are mostly focused on skeletal muscle. Given that immune cells are mobilized and redistributed in response to acute exercise, we conducted two complementary trials to test the hypothesis that a single exercise session alters NAD+ metabolism of peripheral blood mononuclear cells (PBMCs). In a randomized crossover trial (DRKS00017686) with 24 young adults (12 female) we show that acute exercise increases gene expression and protein abundance of several key NAD+ metabolism enzymes with high conformity between high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT). In a longitudinal exercise trial (DRKS00029105) with 12 young adults (6 female) we confirm these results and reveal that - similar to skeletal muscle - NAD+ salvage is pivotal for PBMCs in response to exercise. Nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme of NAD+ salvage pathway, displayed a pronounced increase in gene expression during exercise, which was accompanied by elevated intracellular NAD+ levels and reduced serum levels of the NAD+ precursor nicotinamide. These results demonstrate that acute exercise triggers NAD+ biosynthesis of human PBMCs with potential implications for immunometabolism, immune effector function, and immunological exercise adaptions.

Immune aging and infectious diseases

ABSTRACT

The rise in global life expectancy has led to an increase in the older population, presenting significant challenges in managing infectious diseases. Aging affects the innate and adaptive immune systems, resulting in chronic low-grade inflammation (inflammaging) and immune function decline (immunosenescence). These changes would impair defense mechanisms, increase susceptibility to infections and reduce vaccine efficacy in older adults. Cellular senescence exacerbates these issues by releasing pro-inflammatory factors, further perpetuating chronic inflammation. Moreover, comorbidities, such as cardiovascular disease and diabetes, which are common in older adults, amplify immune dysfunction, while immunosuppressive medications further complicate responses to infections. This review explores the molecular and cellular mechanisms driving inflammaging and immunosenescence, focusing on genomic instability, telomere attrition, and mitochondrial dysfunction. Additionally, we discussed how aging-associated immune alterations influence responses to bacterial, viral, and parasitic infections and evaluated emerging antiaging strategies, aimed at mitigating these effects to improve health outcomes in the aging population.

Sex-specific cytokine, chemokine, and growth factor signatures in T1D patients and progressors

Numerous studies have reported altered cytokine levels in type 1 diabetes (T1D) patients, yet findings remain inconsistent. In this pilot study, we tested the hypothesis that circulating immune markers exhibit sex-based differences in T1D, both prior to and after disease onset. We analyzed 47-48 cytokine, chemokine, and growth factor levels in two cohorts. To assess post-disease differences, we analyzed serum samples from 25 controls and 25 T1D patients. To examine pre-disease progression, we utilized samples from 21 control children and 16 T1D progressors, collected at age 5 years before disease onset. Across all T1D patients and controls, only macrophage colony-stimulating factor and interleukin (IL)-6 showed significant differences. However, we identified notable alterations when comparing sex-age-matched controls and T1D samples. Female T1D patients exhibited lower levels of inflammatory cytokines (tumor necrosis factor-α, IL-6, IL-1a), Th2 cytokines (IL-4, IL-13), and chemokines (macrophage inflammatory protein (MIP)-1α, regulated upon activation, normal T cell expressed and secreted, MIP-3) compared to female controls, differences that were not observed in males. Notably, IL-22 was lower in female T1D patients compared to female controls, whereas it was higher in male T1D patients compared to male controls. Male T1D patients showed elevated levels of growth factors (epidermal growth factor, platelet-derived growth factor-AB/BB) compared to male controls. In T1D progressors, growth-regulated alpha was lower compared to controls in both sexes. Multiple regression analysis further revealed associations between cytokine levels and factors such as age, BMI, and breastfeeding duration. Overall, our findings serve as a proof of concept, highlighting the importance of sex-specific differences in T1D pathogenesis. However, follow-up studies with larger sample sizes are needed to validate and generalize these results.

Demographic diversity in platelet function and response to antiplatelet therapy

Recent studies have highlighted the complexity of platelet biology, revealing their diverse roles beyond hemostasis. Pathological platelet activation is now recognized as a key contributor to thrombosis and inflammation that are both central to cardiovascular disease (CVD). Emerging research emphasizes the significant impact of demographic factors - such as age, sex, race, and ethnicity - on CVD risk and responses to antiplatelet therapies. These population-based differences, shaped by genetic and non-genetic factors, highlight the need for reevaluation of antiplatelet strategies. We address current knowledge and emphasize the pressing need for further research into platelet biology and cardiovascular outcomes across diverse populations. In this review we advocate for tailored therapeutic approaches in CVD based on the recent demographic-focused findings.

Ultrasonographic Evaluation of Vascular Response to Mechanical Compression during Induced Gingival Inflammation

The aim of this study was to evaluate the gingival vascular response to mechanical compression during inflammation using ultrasonography. Four female and 4 male Sinclair mini pigs 18 mo of age were included in the study. Pathogenic bacteria-impregnated silk ligatures were placed around the third premolars (PM3), fourth premolars (PM4), and first molars (M1). Ligatures were placed per quadrant at 2-wk intervals in random order. Ultrasonographic study was performed at 2-wk intervals following baseline until the 10th week. Brightness mode (B-mode) images and color flow cine loops were captured at 2 different conditions: 1 with only coupling gel between the ultrasound transducer and the mucosal surface and 1 with the transducer compressing the mucosal surface. The compression was visually adjusted until minimal to no blood flow was detected in color-flow mode. Compression was facilitated using a solid gel pad attached to the transducer. Strain values were obtained from B-mode images of the gel pad and plotted versus study weeks. The t test comparisons were obtained to the baseline (week 0). Data from female and male pigs were plotted and analyzed separately for comparison. Gel pad strain increased with peak around week 4 and gradually decreased in both sexes. In male pigs, the increase in strain was statistically significant in weeks 2, 4, and 6 of all teeth regions and week 8 of PM4 and M1 regions. In female pigs, the increase in strain was significant in only week 4 of PM4. Higher strain required for stoppage of blood flow implies increased gingival blood flow with inflammation, which corresponds with previous studies. Considerably smaller changes in gel pad strain were noted from female pigs, indicating a smaller increase in gingival blood flow compared with males. This study demonstrated a possible application of intraoral ultrasonography for assessment of gingival inflammation.

The immune-endocrine interplay in sex differential responses to viral infection and COVID-19

Men are at higher risk for developing severe COVID-19 than women, while women are at higher risk for developing post-acute sequelae of COVID-19 (PASC). This highlights the impact of sex differences on immune responses and clinical outcomes of acute COVID-19 or PASC. A dynamic immune-endocrine interface plays an important role in the development of effective immune responses impacting the control of viral infections. In this opinion article we discuss mechanisms underlying the transcriptional and epigenetic regulation of immune responses by sex hormones during viral infections. We propose that disruption of this delicate immune-endocrine interplay can result in worsened outcomes of viral disease. We also posit that insights into these immune mechanisms can propel the development of novel immunomodulatory interventions that leverage immune-endocrine pathways to treat viral infections.

The Effectiveness of COVID-19 Vaccination on Post-Acute Sequelae of SARS-CoV-2 Infection Among Geriatric Patients

This study aims to evaluate the effectiveness of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines in preventing the post-acute sequelae of SARS-CoV-2 infection (PASC), commonly known as long COVID, and reducing all-cause mortality among older patients. A retrospective cohort study was conducted using the TriNetX database. The study cohort consisted of older patients (age ≥ 65 years) with their first COVID-19 illness between January 1, 2022, and May 31, 2024. Participants were divided into vaccinated and unvaccinated groups based on their vaccination status. Propensity score matching (PSM) was used to balance baseline characteristics. Cox regression models and log-rank tests were applied to estimate the hazard ratio (HR) for PASC and all-cause mortality during 30-180 days of follow-up. The study included 189 059 geriatric patients who contracted SARS-CoV-2, with 5615 vaccinated and 183 444 unvaccinated. After PSM, each group contained 5615 patients. Vaccinated patients exhibited a significantly lower incidence of PASC symptoms (HR = 0.852, 95% CI: 0.778-0.933, p = 0.0005), particularly anxiety and depression, with a HR of 0.710 (95% CI: 0.575-0.878, p = 0.0015). Vaccination was also significantly associated with reduced all-cause mortality (HR = 0.231, 95% CI: 0.136-0.394, p < 0.0001). The findings highlight the effectiveness of COVID-19 vaccination in mitigating the development of PASC and decreasing mortality among older patients.

Peripheral Blood Leukocyte Subpopulation Changes in Reaction to an Acute Psychosocial Stressor as Compared to an Active Placebo-Stressor in Healthy Young Males: Mediating Effects of Major Stress-Reactive Endocrine Parameters

Psychosocial stress has been proposed to induce a redistribution of immune cells, but a comparison with an active placebo-psychosocial stress control condition is lacking so far. We investigated immune cell redistribution due to psychosocial stress compared to that resulting from an active placebo-psychosocial stress but otherwise identical control condition. Moreover, we tested for mediating effects of endocrine parameters and blood volume changes. The final study sample comprised 64 healthy young men who underwent either a psychosocial stress condition (Trier Social Stress Test; TSST; n = 38) or an active placebo-psychosocial stress control condition (PlacTSST; n = 26). Immune cell counts and hemoglobin, epinephrine, norepinephrine, ACTH, renin, and aldosterone levels, as well as those of saliva cortisol, were determined before and up to 30 min after the TSST/PlacTSST. The TSST induced greater increases in total leukocyte, monocyte, and lymphocyte levels as compared to the PlacTSST (p's ≤ 0.001), but in not granulocyte counts. Neutrophil granulocyte counts increased in reaction to both the TSST and PlacTSST (p's ≤ 0.001), while eosinophil and basophil granulocyte counts did not. The psychosocial stress-induced increases in immune cell counts from baseline to peak (i.e., +1 min after TSST cessation) were independently mediated by parallel increases in epinephrine (ab's ≤ -0.43; 95% CIs [LLs ≤ -0.66; ULs ≤ -0.09]). Subsequent decreases in immune cell counts from +1 min to +10 min after psychosocial stress cessation were mediated by parallel epinephrine, renin, and blood volume decreases (ab's ≥ 0.17; 95% CIs [LLs ≥ 0.02; ULs ≥ 0.35]). Our findings indicate that psychosocial stress specifically induces immune cell count increases in most leukocyte subpopulations that are not secondary to the physical or cognitive demands of the stress task. Increases in the number of circulating neutrophil granulocytes, however, are not psychosocial stress-specific and even occur in situations with a low probability of threat or harm. Our findings point to a major role of epinephrine in mediating stress-induced immune cell count increases and of epinephrine, renin, and blood volume changes in mediating subsequent immune cell count decreases from +1 min to +10 min after psychosocial stress cessation.

LRRC8A drives NADPH oxidase-mediated mitochondrial dysfunction and inflammation in allergic rhinitis

OBJECTIVES

Allergic rhinitis (AR) is a complex disorder with variable pathogenesis. Increasing evidence suggests that the LRRC8A is involved in maintaining cellular stability, regulating immune cell activation and function, and playing significant roles in inflammation. However, the involvement of LRRC8A in AR inflammation and its underlying mechanisms remain unclear.

METHODS

LRRC8A expression in AR patients, confirmed by qRT-PCR and Western blotting, was analyzed to investigate its relationship with the clinical characteristics of AR patients. In vitro, IL-13 stimulated HNEpCs to establish a Th2 inflammation model, with subsequent LRRC8A knockout or overexpression. NOX1/NOX4 inhibitor (GKT137831) and chloride channel inhibitor (DCPIB) were utilized to investigate AR development mechanisms during LRRC8A overexpression. An OVA-induced AR model with nasal mucosa LRRC8A knockdown confirmed LRRC8A's regulatory role in AR inflammation.

RESULTS

LRRC8A mRNA and protein levels were significantly elevated in AR patients, positively correlating with NADPH oxidase subunits and Th2 inflammatory markers. In vitro, IL-13 stimulation of HNEpCs resulted in upregulation of LRRC8A and increased expression of NOX1, NOX4, and p22phox, along with mitochondrial dysfunction and NF-κB pathway activation. The knockout of LRRC8A reversed these effects. In nasal mucosal epithelial cells, DCPIB and GKT137831 completely blocked mitochondrial dysfunction caused by the overexpression of LRRC8A, which led to up-regulation of NOX1, NOX4, and p22phox. In vivo, knocking down LRRC8A reduced eosinophil infiltration, downregulated the expression of NOX1, NOX4, p22phox IL-4, IL-5, and IL-13, and decreased NF-κB pathway activation.

CONCLUSION

LRRC8A drives the upregulation of NOX1, NOX4, and p22phox, leading to ROS overproduction and mitochondrial dysfunction. It also activates NF-κB, ultimately leading to nasal mucosal epithelial inflammation. LRRC8A may be a potential target for the treatment of AR.

Prognostic Significance of PD-L1 Expression on Circulating Myeloid-Derived Suppressor Cells in NSCLC Patients Treated with Anti-PD-1/PD-L1 Checkpoint Inhibitors

Even though anti-PD-1/PD-L1 immune checkpoint inhibitors (ICIs) in non-small cell lung cancer (NSCLC) have improved survival, a high percentage of patients still do not respond to ICIs. Myeloid-derived suppressor cells (MDSCs) are circulating cells that express PD-L1 and can infiltrate and proliferate in the tumor microenvironment, inducing immunosuppression. By evaluating changes in PD-L1 expression of live peripheral blood MDSCs, we are able to define a new PD-L1 index, useful in predicting ICI escape in NSCLC patients before initiating anti-PD-1/PD-L1 immunotherapy. In this study, a cohort of 37 NSCLC patients was prospectively analyzed, obtaining independent PD-L1 indexes. In patients with a PD-L1 index > 5.88, progressive disease occurred in 58.33% of patients [median progression-free survival (PFS) = 5.73 months; 95%CI = 2.67-20.53], showing significant differences when compared with patients with a PD-L1 index ≤ 5.88, in whom 7.69% progressed and median PFS was not reached (NR); p-value = 0.0042. Overall survival (OS) was significantly worse in patients with a high vs. low PD-L1 index (41.67% vs. 76.92%; median OS = 18.03 months, 95%CI = 6.77-25.23 vs. NR, 95%CI = 1.87-NR; p-value = 0.035). The PD-L1 index can be applied to stratify NSCLC patients according to their probability of response to ICIs at baseline. In addition to quantifying tumoral expression, this index could be used to compare nonresponse to treatment.

Factors Predicting COVID-19 Vaccine Effectiveness and Longevity of Humoral Immune Responses

The COVID-19 pandemic, caused by SARS-CoV-2, prompted global efforts to develop vaccines to control the disease. Various vaccines, including mRNA (BNT162b2, mRNA-1273), adenoviral vector (ChAdOx1, Ad26.COV2.S), and inactivated virus platforms (BBIBP-CorV, CoronaVac), elicit high-titer, protective antibodies against the virus, but long-term antibody durability and effectiveness vary. The objective of this study is to elucidate the factors that influence vaccine effectiveness (VE) and the longevity of humoral immune responses to COVID-19 vaccines through a review of the relevant literature, including clinical and real-world studies. Here, we discuss the humoral immune response to different COVID-19 vaccines and identify factors influencing VE and antibody longevity. Despite initial robust immune responses, vaccine-induced immunity wanes over time, particularly with the emergence of variants, such as Delta and Omicron, that exhibit immune escape mechanisms. Additionally, the durability of the humoral immune responses elicited by different vaccine platforms, along with the identification of essential determinants of long-term protection-like pre-existing immunity, booster doses, hybrid immunity, and demographic factors-are critical for protecting against severe COVID-19. Booster vaccinations substantially restore neutralizing antibody levels, especially against immune-evasive variants, while individuals with hybrid immunity have a more durable and potent immune response. Importantly, comorbidities such as diabetes, cardiovascular disease, chronic kidney disease, and cancer significantly reduce the magnitude and longevity of vaccine-induced protection. Immunocompromised individuals, particularly those undergoing chemotherapy and those with hematologic malignancies, have diminished humoral responses and benefit disproportionately from booster vaccinations. Age and sex also influence immune responses, with older adults experiencing accelerated antibody decline and females generally exhibiting stronger humoral responses compared to males. Understanding the variables affecting immune protection is crucial to improving vaccine strategies and predicting VE and protection against COVID-19.

Sex differences in postacute infection syndromes

Postacute infection syndromes like Long Covid disproportionately affect females, differing in prevalence, symptoms, and potential causes from males. This Viewpoint highlights these sex differences, gaps in current understanding, and the critical need for sex-based research.

GPER1 signaling restricts macrophage proliferation and accumulation in human hepatocellular carcinoma

Background

Sex hormones and their related receptors have been reported to impact the development and progression of tumors. However, their influence on the composition and function of the tumor microenvironment is not well understood. We aimed to investigate the influence of sex disparities on the proliferation and accumulation of macrophages, one of the major components of the tumor microenvironment, in hepatocellular carcinoma (HCC).

Methods

Immunohistochemistry was applied to assess the density of immune cells in HCC tissues. The role of sex hormone related signaling in macrophage proliferation was determined by immunofluorescence and flow cytometry. The underlying regulatory mechanisms were examined with both in vitro experiments and murine HCC models.

Results

We found higher levels of macrophage proliferation and density in tumor tissues from male patients compared to females. The expression of G protein-coupled estrogen receptor 1 (GPER1), a non-classical estrogen receptor, was significantly decreased in proliferating macrophages, and was inversely correlated with macrophage proliferation in HCC tumors. Activation of GPER1 signaling with a selective agonist G-1 suppressed macrophage proliferation by downregulating the MEK/ERK pathway. Additionally, G-1 treatment reduced PD-L1 expression on macrophages and delayed tumor growth in mice. Moreover, patients with a higher percentage of GPER1+ macrophages exhibited longer overall survival and recurrence-free survival compared to those with a lower level.

Conclusions

These findings reveal a novel role of GPER1 signaling in regulating macrophage proliferation and function in HCC tumors and may offer a potential strategy for designing therapies based on understanding sex-related disparities of patients.

The impact of sex/gender-specific funding and editorial policies on biomedical research outcomes: a cross-national analysis (2000-2021)

Reflecting sex and gender characteristics in biomedical research is critical to improving health outcomes and reducing adverse effects from medical treatments. This study investigates the impact of sex/gender-specific funding policies and journal editorial standards on the integration of sex/gender analysis in biomedical research publications. Using data from the United States, Canada, the United Kingdom, and other countries between 2000 and 2021, we assessed how these policies influenced research output in the fields of medicine and life sciences. Our findings show that countries with progressive funding policies and journals promoting sex/gender-based reporting have significantly improved research quality and publication rates. This highlights the importance of coordinated policy efforts and editorial practices in advancing integrated sex/gender research. We recommend continued global efforts from policymakers, funding bodies, and journals to embed sex/gender perspectives in scientific inquiry, ensuring more effective and equitable biomedical advancements.

Human-specific protein-coding and lncRNA genes cast sex-biased genes in the brain and their relationships with brain diseases

BACKGROUND

Gene expression shows sex bias in the brain as it does in other organs. Since female and male humans exhibit noticeable differences in emotions, logical thinking, movement, spatial orientation, and even the incidence of neurological disorders, sex biases in the brain are especially interesting, but how they are determined, whether they are conserved or lineage specific, and what the consequences of the biases are, remain poorly explored and understood.

METHODS

Based on RNA-seq datasets from 16  and 14 brain regions in humans and macaques across developmental periods and from patients with brain diseases, we used linear mixed models (LMMs) to differentiate variations in gene expression caused by factors of interest and confounding factors and identify four types of sex-biased genes. Effect size and confidence in each effect were measured upon the local false sign rate (LFSR). We utilized the biomaRt R package to acquire orthologous genes in humans and macaques from the BioMart Ensembl website. Transcriptional regulation of sex-biased genes by sex hormones and lncRNAs were analyzed using the CellOracle, GENIE3, and Longtarget programs. Sex-biased genes' functions were revealed by gene set enrichment analysis using multiple methods.

RESULTS

Lineage-specific sex-biased genes greatly determine the distinct sex biases in human and macaque brains. In humans, those encoding proteins contribute directly to immune-related functions, and those encoding lncRNAs intensively regulate the expression of other sex-biased genes, especially genes with immune-related functions. The identified sex-specific differentially expressed genes (ssDEGs) upon gene expression in disease and normal samples also indicate that protein-coding ssDEGs are conserved in humans and macaques but that lncRNA ssDEGs are not conserved. The results answer the above questions, reveal an intrinsic relationship between sex biases in the brain and sex-biased susceptibility to brain diseases, and will help researchers investigate human- and sex-specific ncRNA targets for brain diseases.

CONCLUSIONS

Human-specific genes greatly cast sex-biased genes in the brain and their relationships with brain diseases, with protein-coding genes contributing to immune response related functions and lncRNA genes critically regulating sex-biased genes. The high proportions of lineage-specific lncRNAs in mammalian genomes indicate that sex biases may have evolved rapidly in not only the brain but also other organs.

Overlapping conditions in Long COVID at a multisite academic center

Background

Many patients experience persistent symptoms after COVID-19, a syndrome referred to as Long COVID (LC). The goal of this study was to identify novel new or worsening comorbidities self-reported in patients with LC.

Methods

Patients diagnosed with LC (n = 732) at the Mayo Long COVID Care Clinic in Rochester, Minnesota and Jacksonville, Florida were sent questionnaires to assess the development of new or worsening comorbidities following COVID-19 compared to patients with SARS-CoV-2 that did not develop LC (controls). Both groups were also asked questions screening for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), generalized joint hypermobility (GJH) and orthostatic intolerance. 247 people with LC (33.7%) and 40 controls (50%) responded to the surveys.

Results

In this study LC patients averaged 53 years of age and were predominantly White (95%) women (75%). The greatest prevalence of new or worsening comorbidities following SARS-CoV-2 infection in patients with LC vs. controls reported in this study were pain (94.4% vs. 0%, p < 0.001), neurological (92.4% vs. 15.4%, p < 0.001), sleep (82.8% vs. 5.3%, p < 0.001), skin (69.8% vs. 0%, p < 0.001), and genitourinary (60.6% vs. 25.0%, p = 0.029) issues. 58% of LC patients screened positive for ME/CFS vs. 0% of controls (p < 0.001), 27% positive for GJH compared to 10% of controls (p = 0.026), and a positive average score of 4.0 on orthostatic intolerance vs. 0 (p < 0.001). The majority of LC patients with ME/CFS were women (77%).

Conclusion

We found that comorbidities across 12 surveyed categories were increased in patients following SARS-CoV-2 infection. Our data also support the overlap of LC with ME/CFS, GJH, and orthostatic intolerance. We discuss the pathophysiologic, research, and clinical implications of identifying these conditions with LC.

The influence of sex-specific factors on biological transformations and health outcomes in aging processes

The aging process demonstrates notable differences between males and females, which are key factors in disease susceptibility and lifespan. The differences in sex chromosomes are fundamental to the presence of sex bias in organisms. Moreover, sex-specific epigenetic modifications and changes in sex hormone levels impact the development of immunity differently during embryonic development and beyond. Mitochondria, telomeres, homeodynamic space, and intestinal flora are intricately connected to sex differences in aging. These elements can have diverse effects on men and women, resulting in unique biological transformations and health outcomes as they grow older. This review explores how sex interacts with these elements and shapes the aging process.

Obesity intensifies sex-specific interferon signaling to selectively worsen central nervous system autoimmunity in females

Obesity has been implicated in the rise of autoimmunity in women. We report that obesity induces a serum protein signature that is associated with T helper 1 (Th1), interleukin (IL)-17, and multiple sclerosis (MS) signaling pathways selectively in human females. Females, but not male mice, subjected to diet-induced overweightness/obesity (DIO) exhibited upregulated Th1/IL-17 inflammation in the central nervous system during experimental autoimmune encephalomyelitis, a model of MS. This was associated with worsened disability and a heightened expansion of myelin-specific Th1 cells in the peripheral lymphoid organs. Moreover, at steady state, DIO increased serum levels of interferon (IFN)-α and potentiated STAT1 expression and IFN-γ production by naive CD4+ T cells uniquely in female mice. This T cell phenotype was driven by increased adiposity and was prevented by the removal of ovaries or knockdown of the type I IFN receptor in T cells. Our findings offer a mechanistic explanation of how obesity enhances autoimmunity.

Sex-specific molecular signature of mouse podocytes in homeostasis and in response to pharmacological challenge with rapamycin

BACKGROUND

Sex differences exist in the prevalence and progression of major glomerular diseases. Podocytes are the essential cell-type in the kidney which maintain the physiological blood-urine barrier, and pathological changes in podocyte homeostasis are critical accelerators of impairment of kidney function. However, sex-specific molecular signatures of podocytes under physiological and stress conditions remain unknown. This work aimed at identifying sexual dimorphic molecular signatures of podocytes under physiological condition and pharmacologically challenged homeostasis with mechanistic target of rapamycin (mTOR) inhibition. mTOR is a crucial regulator involved in a variety of physiological and pathological stress responses in the kidney and inhibition of this pathway may therefore serve as a general stress challenger to get fundamental insights into sex differences in podocytes.

METHODS

The genomic ROSAmT/mG-NPHS2 Cre mouse model was used which allows obtaining highly pure podocyte fractions for cell-specific molecular analyses, and vehicle or pharmacologic treatment with the mTOR inhibitor rapamycin was performed for 3 weeks. Subsequently, deep RNA sequencing and proteomics were performed of the isolated podocytes to identify intrinsic sex differences. Studies were supplemented with metabolomics from kidney cortex tissues.

RESULTS

Although kidney function and morphology remained normal in all experimental groups, RNA sequencing, proteomics and metabolomics revealed strong intrinsic sex differences in the expression levels of mitochondrial, translation and structural transcripts, protein abundances and regulation of metabolic pathways. Interestingly, rapamycin abolished prominent sex-specific clustering of podocyte gene expression and induced major changes only in male transcriptome. Several sex-biased transcription factors could be identified as possible upstream regulators of these sexually dimorphic responses. Concordant to transcriptomics, metabolomic changes were more prominent in males. Remarkably, high number of previously reported kidney disease genes showed intrinsic sexual dimorphism and/or different response patterns towards mTOR inhibition.

CONCLUSIONS

Our results highlight remarkable intrinsic sex-differences and sex-specific response patterns towards pharmacological challenged podocyte homeostasis which might fundamentally contribute to sex differences in kidney disease susceptibilities and progression. This work provides rationale and an in-depth database for novel targets to be tested in specific kidney disease models to advance with sex-specific treatment strategies.

COVID-19 vaccine uptake inequality among older adults: A multidimensional demographic analysis

BACKGROUND

Age, race, ethnicity, and sex are important determinants of coronavirus disease of 2019 (COVID-19) outcomes. Older adults (65 years and older) are at the highest risk of COVID-19 morbidity and mortality. Analyzing their vaccine uptake by subclassifying demographics is rare and can assist vaccination policies. This study investigates COVID-19 dose 1 and 2 vaccine uptakes among them by race, ethnicity, and sex.

METHODS

Immunization registry data were used to calculate temporal changes in older adults' COVID-19 vaccine uptake by race, ethnicity, race-sex, and ethnicity-sex in Kentucky's most populous county, Jefferson County, during the first 6 quarters of the COVID-19 vaccination program.

RESULTS

By May 2022, the county's Asian residents had the highest dose 1 and 2 vaccination rates (97.0% and 80.4%), then White residents (90.0% and 80.2%). Black residents had one of the lowest COVID-19 vaccination rates (87.3% and 77.3%). The rate among Hispanic residents (82.0% and 66.4%) was considerably lower than non-Hispanic residents (90.2% and 80.1%). The rates were consistently lower in males.

CONCLUSIONS

Racial, ethnic, and sex-based COVID-19 vaccine inequalities were largely maintained during the study period. Vaccine rollout practices and promotional programs should aim to boost the uptake of the COVID-19 vaccination among racial minority and male older adults.

Revisiting sex as a biological variable in hypertension research

Half of adults in the United States have hypertension as defined by clinical practice guidelines. Interestingly, women are generally more likely to be aware of their hypertension and have their blood pressure controlled with treatment compared with men, yet hypertension-related mortality is greater in women. This may reflect the fact that the female sex remains underrepresented in clinical and basic science studies investigating the effectiveness of therapies and the mechanisms controlling blood pressure. This Review provides an overview of the impact of the way hypertension research has explored sex as a biological variable (SABV). Emphasis is placed on epidemiological studies, hypertension clinical trials, the genetics of hypertension, sex differences in immunology and gut microbiota in hypertension, and the effect of sex on the central control of blood pressure. The goal is to offer historical perspective on SABV in hypertension, highlight recent studies that include SABV, and identify key gaps in SABV inclusion and questions that remain in the field. Through continued awareness campaigns and engagement/education at the level of funding agencies, individual investigators, and in the editorial peer review system, investigation of SABV in the field of hypertension research will ultimately lead to improved clinical outcomes.

No sex-dependent mortality in an amphibian upon infection with the chytrid fungus, Batrachochytrium dendrobatidis

One of the major factors driving the currently ongoing biodiversity crisis is the anthropogenic spread of infectious diseases. Diseases can have conspicuous consequences, such as mass mortality events, but may also exert covert but similarly severe effects, such as sex ratio distortion via sex-biased mortality. Chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd) is among the most important threats to amphibian biodiversity. Yet, whether Bd infection can skew sex ratios in amphibians is currently unknown, although such a hidden effect may cause the already dwindling amphibian populations to collapse. To investigate this possibility, we collected common toad (Bufo bufo) tadpoles from a natural habitat in Hungary and continuously treated them until metamorphosis with sterile Bd culture medium (control), or a liquid culture of a Hungarian or a Spanish Bd isolate. Bd prevalence was high in animals that died during the experiment but was almost zero in individuals that survived until the end of the experiment. Both Bd treatments significantly reduced survival after metamorphosis, but we did not observe sex-dependent mortality in either treatment. However, a small number of genotypically female individuals developed male phenotype (testes) in the Spanish Bd isolate treatment. Therefore, future research is needed to ascertain if larval Bd infection can affect sex ratio in common toads through female-to-male sex reversal.

Innate immunity in peripheral tissues is differentially impaired under normal and endotoxic conditions in aging

Chronic low-grade inflammation is a hallmark of aging, aka "inflammaging", which is linked to a wide range of age-associated diseases. Immune dysfunction increases disease susceptibility, and increases morbidity and mortality of aging. Innate immune cells, including monocytes, macrophages and neutrophils, are the first responders of host defense and the key mediators of various metabolic and inflammatory insults. Currently, the understanding of innate immune programming in aging is largely fragmented. Here we investigated the phenotypic and functional properties of innate immune cells in various peripheral tissues of young and aged mice under normal and endotoxic conditions. Under the steady state, aged mice showed elevated pro-inflammatory monocytes/macrophages in peripheral blood, adipose tissue, liver, and colon. Under lipopolysaccharide (LPS)-induced inflammatory state, the innate immune cells of aged mice showed a different response to LPS stimulus than that of young mice. LPS-induced immune responses displayed differential profiles in different tissues and cell types. In the peripheral blood, when responding to LPS, the aged mice showed higher neutrophils, but lower pro-inflammatory monocytes than that in young mice. In the peritoneal fluid, while young mice exhibited significantly elevated pro-inflammatory neutrophils and macrophages in response to LPS, aged mice exhibited decreased pro-inflammatory neutrophils and variable cytokine responses in macrophages. In the adipose tissue, LPS induced less infiltrated neutrophils but more infiltrated macrophages in old mice than young mice. In the liver, aged mice showed a more robust increase of pro-inflammatory macrophages compared to that in young mice under LPS stimulation. In colon, macrophages showed relatively mild response to LPS in both young and old mice. We have further tested bone-marrow derived macrophages (BMDM) from young and aged mice, we found that BMDM from aged mice have impaired polarization, displaying higher expression of pro-inflammatory markers than those from young mice. These data collectively suggest that innate immunity in peripheral tissues is impaired in aging, and the dysregulation of immunity is tissue- and cell-dependent. Our findings in the rodent model underscore the complexity of aging immunity. Further investigation is needed to determine whether the immune profile observed in aged mice is applicable in age-associated diseases in humans.

Mast cell-derived chymases are essential for the resolution of inflammatory pain in mice

Immune cells play a critical role in the transition from acute to chronic pain. However, the role of mast cells in pain remains under-investigated. Here, we demonstrated that the resolution of inflammatory pain is markedly delayed in mast-cell-deficient mice. In response to Complete Freund Adjuvant (CFA), mast-cell-deficient mice showed greater levels of nitric oxide and altered cytokine/chemokine profile in inflamed skin in both sexes. In Wild-Type (WT) mice, the number of mast cell and mast cell-derived chymases; chymase 1 (CMA1) and mast cell protease 4 (MCPT4) increased in the inflamed skin. Inhibiting chymase enzymatic activity delayed the resolution of inflammatory pain. Consistently, local pharmacological administration of recombinant CMA1 and MCPT4 promoted the resolution of pain hypersensitivity and attenuated the upregulation of cytokines and chemokines under inflammation. We identified CCL9 as a target of MCPT4. Inhibition of CCL9 promoted recruitment of CD206 + myeloid cells and alleviated inflammatory pain. Our work reveals a new role of mast cell-derived chymases in preventing the transition from acute to chronic pain and suggests new therapeutic avenues for the treatment of inflammatory pain.

Summary

Mast cell-derived chymases play an unexpected role in the resolution of inflammatory pain and regulate the immune response.

Graphical abstract

Sex-specific impact of psychosocial stress on hematopoiesis and blood leukocytes

Stress exposure has been shown to modulate innate and adaptive immune responses. Indeed, stress favors myelopoiesis and monocyte generation and contributes to cardiovascular disease development. As sex hormones regulate innate and adaptive immune responses, we decided to investigate whether stress exposure leads to a different immune response in female and male mice. Our data demonstrated that psychosocial stressinduced neutrophilia in male, but not female mice. Importantly, we identified that B-cell numbers were reduced in female, but not male mice upon exposure to stress. Thus, our study revealed that the stress-induced immune alterations are sex-dependent, and this is an important feature to consider for future investigations.

Analysis of sex-biased gene expression in a Eurasian admixed population

Sex-biased gene expression differs across human populations; however, the underlying genetic basis and molecular mechanisms remain largely unknown. Here, we explore the influence of ancestry on sex differences in the human transcriptome and its genetic effects on a Eurasian admixed population: Uyghurs living in Xinjiang (XJU), by analyzing whole-genome sequencing data and transcriptome data of 90 XJU and 40 unrelated Han Chinese individuals. We identified 302 sex-biased expressed genes and 174 sex-biased cis-expression quantitative loci (sb-cis-eQTLs) in XJU, which were enriched in innate immune-related functions, indicating sex differences in immunity. Notably, approximately one-quarter of the sb-cis-eQTLs showed a strong correlation with ancestry composition; i.e. populations of similar ancestry tended to show similar patterns of sex-biased gene expression. Our analysis further suggested that genetic admixture induced a moderate degree of sex-biased gene expression. Interestingly, analysis of chromosome interactions revealed that the X chromosome acted on autosomal immunity-associated genes, partially explaining the sex-biased phenotypic differences. Our work extends the knowledge of sex-biased gene expression from the perspective of genetic admixture and bridges the gap in the exploration of sex-biased phenotypes shaped by autosome and X-chromosome interactions. Notably, we demonstrated that sex chromosomes cannot fully explain sex differentiation in immune-related phenotypes.

Sex-Specific Response to A1BG Loss Results in Female Dilated Cardiomyopathy

Background

Cardiac disease often manifests differently in terms of frequency and pathology between men and women. However, the mechanisms underlying these differences are not fully understood. The glycoprotein A1BG is necessary for proper cardiac function in females but not males. Despite this, the role of A1BG in the female heart remains poorly studied.

Methods

To determine the sex differential function of A1BG, we generated a novel conditional A1bg allele and a novel conditional A1bg Rosa26 knockin allele. Histology, electrocardiography, transcriptional profiling (RNA-seq), transmission electron microscopy, western blot analyses, mass spectrometry, and immunohistochemistry were used to assess cardiac structure and function.

Results

The study reveals that the absence of A1BG results in significant cardiac dysfunction in female but not male mice. Gene expression underscores that A1BG plays a critical role in metabolic processes and the integrity of intercalated discs in female cardiomyocytes. This dysfunction may be related to sex-specific A1BG cardiac interactomes and manifests as structural and functional alterations in the left ventricle indicative of dilated cardiomyopathy, thus suggesting a sex-specific requirement for A1BG in cardiac health.

Conclusion

The loss of A1BG in cardiomyocytes leads to dilated cardiomyopathy in females, not males.

Pediatric respiratory pathogen dynamics in Southern Sichuan, China: a retrospective analysis of gender, age, and seasonal trends

Objective

To address the research gap in the epidemiology of pediatric respiratory tract infections (RTIs) in Luzhou, Southern Sichuan, China, by analyzing respiratory pathogens in a large pediatric cohort from 2018 to 2021, covering the pre- and during-COVID-19 periods.

Methods

This study conducted a retrospective analysis of children with RTIs in Luzhou from July 2018 to January 2021. Strict exclusion criteria were applied to ensure an accurate representation of the pediatric population. Pathogen detection included viruses, bacteria, and atypical agents.

Results

Pathogens were identified in 52.8% of 12,546 cases. Viruses accounted for 32.2% of infections, bacteria for 29.8%, and atypical agents for 29.7%, with significant findings of Staphylococcus aureus, Moraxella catarrhalis, and Mycoplasma pneumoniae. Age-related analysis indicated a higher incidence of bacterial infections in infants and viral infections in preschool-aged children, with atypical pathogens being most prevalent in 3-5-year-olds. Gender-based analysis, adjusted for age, revealed similar overall pathogen presence; however, females were more susceptible to viral infections, while males were more prone to Streptococcus pneumoniae. Notably, there was an unusual increase in pathogen cases during spring, potentially influenced by behavioral changes and public health measures related to COVID-19. Co-infections were identified as a significant risk factor for the development of pneumonia.

Conclusion

The study provides essential insights into the epidemiology of respiratory pathogens in pediatric populations, emphasizing the need for healthcare strategies tailored to age, gender, and seasonality. The findings highlight the impact of environmental and public health factors, including COVID-19 measures, on respiratory pathogen prevalence, underscoring the importance of targeted diagnostic and treatment protocols in pediatric respiratory infections.

The relationship between different fatty acids intake and the depressive symptoms: A population-based study

BACKGROUND

Depression is a common psychological disorder worldwide, affecting mental and physical health. Previous studies have explored the benefits of polyunsaturated fatty acids (PUFAs) intake in depressive symptoms; however, few studies have focused on the association between all types of fatty acids intake and depressive symptoms. Therefore, we explored the relationship between the intake of different fatty acids intake and the risk of depressive symptoms.

METHODS

The study was based on the data from the 2005-2018 National Health and Nutrition Examination Survey (NHANES), a large US-based database. We used a nutrient residual model and multi-nutrient density model for the analysis. We calculated the nutrient density and residual in men and women separately, and the fatty acids intake was divided into quartiles based on the sex distribution. The relationship between the depressive symptoms and the intake of different fatty acids was examined using logistic regression; furthermore, we explored the relationships separately in men and women.

RESULTS

The intake of monounsaturated fatty acids (MUFAs) and PUFAs, particularly n-3 and n-6 PUFAs, were associated with reduced odds ratios for depressive symptoms. The inverse relationship between the intake of MUFAs, PUFAs, n-3, and n-6 PUFAs and depressive symptoms was stronger in women. The inverse relationship between total fatty acid (TFAs) intake and depressive symptoms existed only in a single model. In contrast, saturated fatty acid (SFAs) intake was not related to depressive symptoms.

CONCLUSION

Consuming MUFAs and PUFAs can counteract the depressive symptoms, especially in women.

Sex-based differences in the lung immune microenvironment are associated with an increased risk of lung cancer in women

OBJECTIVE

Lung cancer remains a major cause of mortality worldwide, necessitating further understanding of carcinogenesis and its driving factors, including those influenced by sex-dependent variables. We hypothesized that sex-specific lung immune composition may contribute to a greater risk of lung cancer in women.

METHODS

Data from 1056 lung cancer screenings were examined for an association between sex and lung cancer risk using time-to-event analyses. Immune profiling by flow cytometry was performed on male and female lungs of 3 independent mouse models: nontumor bearing, KRAS mutated, and urethane-exposed carcinogenic. A comparable analysis was performed on human bronchoalveolar lavage samples (n = 81) from patients with lung cancer.

RESULTS

Of the high-risk screening cohort examined, 60 patients (5.7%) developed lung cancer during median follow-up of 43.4 months. Multivariable stepwise modeling retained female sex (hazard ratio, 1.56; P < .01) and age (P < .01) as prognostic indicators for lung cancer development. Female lung immune profiles in patients included T-cell phenotypes consistent with exhaustion (eg, higher proportions of PD-1+ Ki67-; P = .02), an expanded pool of regulatory T-cells (P = .03), reduced effector T-cell frequencies (P = .008), and enhancements in suppressive myeloid populations (P = .02) versus male patients, and this is recapitulated in mouse studies.

CONCLUSIONS

Female smokers display higher risk for lung cancer. In murine models and humans, female sex is associated with robust immunosuppression within the lung. Further examination of this link will be important in developing immune-based approaches to lung cancer interception and their optimal application across the sexes.

Sex-dependent effects of chronic intermittent hypoxia: implication for obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) affects 10-26% of adults in the United States with known sex differences in prevalence and severity. OSA is characterized by elevated inflammation, oxidative stress (OS), and cognitive dysfunction. However, there is a paucity of data regarding the role of sex in the OSA phenotype. Prior findings suggest women exhibit different OSA phenotypes than men, which could result in under-reported OSA prevalence in women. To examine the relationship between OSA and sex, we used chronic intermittent hypoxia (CIH) to model OSA in rats. We hypothesized that CIH would produce sex-dependent phenotypes of inflammation, OS, and cognitive dysfunction, and these sex differences would be dependent on mitochondrial oxidative stress (mtOS).

METHODS

Adult male and female Sprague Dawley rats were exposed to CIH or normoxia for 14 days to examine the impact of sex on CIH-associated circulating inflammation (IL-1β, IL-6, IL-10, TNF-α), circulating steroid hormones, circulating OS, and behavior (recollective and spatial memory; gross and fine motor function; anxiety-like behaviors; and compulsive behaviors). Rats were implanted with osmotic minipumps containing either a mitochondria-targeting antioxidant (MitoTEMPOL) or saline vehicle 1 week prior to CIH initiation to examine how inhibiting mtOS would affect the CIH phenotype.

RESULTS

Sex-specific differences in CIH-induced inflammation, OS, motor function, and compulsive behavior were observed. In female rats, CIH increased inflammation (plasma IL-6 and IL-6/IL-10 ratio) and impaired fine motor function. Conversely, CIH elevated circulating OS and compulsivity in males. These sex-dependent effects of CIH were blocked by inhibiting mtOS. Interestingly, CIH impaired recollective memory in both sexes but these effects were not mediated by mtOS. No effects of CIH were observed on spatial memory, gross motor function, or anxiety-like behavior, regardless of sex.

CONCLUSIONS

Our results indicate that the impact of CIH is dependent on sex, such as an inflammatory response and OS response in females and males, respectively, that are mediated by mtOS. Interestingly, there was no effect of sex or mtOS in CIH-induced impairment of recollective memory. These results indicate that mtOS is involved in the sex differences observed in CIH, but a different mechanism underlies CIH-induced memory impairments.

Sex disparities revealed by single-cell and bulk sequencing and their impacts on the efficacy of immunotherapy in esophageal cancer

BACKGROUND

There is an ongoing debate on whether sex affects immune-suppressive tumor microenvironment and immunotherapy. Here, we explored the underlying molecular bases for sex dimorphisms and their impact on the efficacy of immunotherapy in esophageal cancer (EC).

METHODS

2360 EC patients from phase 3 trials were pooled to compare overall survivals by calculating hazard ratios (HRs) and their 95% confidence intervals (CIs). Genomic data of 1425 samples were integrated to depict the genomic landscapes and antigenic features. We also examined the sex disparities based on single-cell RNA sequencing and T cell receptor-sequencing data from 105,145 immune cells in 60 patients.

RESULTS

Immunotherapy was associated with favorable outcomes in men (HR, 0.71; 95% CI, 0.65-0.79; P < 0.001), but not in women (HR, 0.98; 95% CI, 0.78-1.23; P = 0.84) (Pinteraction =0.02). The frequencies of 8 gene mutations, 12 single base substitutions signatures, and 131 reactome pathways were significantly different between male and female. Additionally, six subtypes of HLA-II antigens were enriched in women. Hence, we constructed and then validated a sex-related signature to better predict the outcomes of immunotherapy. Exhausted CD8+ T cells were highly infiltrated in men, while naïve CD8+ T cells were more common in women. Further examinations on multiple malignancies suggested exhausted CD8+ T cells were enriched in patients who responded to immunotherapy.

CONCLUSIONS

Our study delineated the robust genomic and cellular sex disparities in EC. Furthermore, male, rather than female, derived significantly benefits from immunotherapy. These results have implications for treatment decision-making and developing immunotherapy for personalized care. In the past several years, immunotherapy has gradually replaced the traditional chemotherapy as the standard treatment in esophageal cancer. It is well-established that immunological responses in male and female differ significantly. However, there is an ongoing debate on whether sex can impact the treatment outcomes in immunotherapy. In the present study, we systematically characterized the genomic and cellular landscapes of esophageal cancer, and revealed the significant differences between male and female patients. Furthermore, with over 2000 patients with esophageal cancer, we showed that only men can benefit from immunotherapy. In women, immunotherapy failed to show superior over chemotherapy. These results have implications for treatment decision-making and developing next-generation immunotherapy for personalized care.

Novel Perspectives in Chronic Kidney Disease-Specific Cardiovascular Disease

Chronic kidney disease (CKD) affects > 10% of the global adult population and significantly increases the risk of cardiovascular disease (CVD), which remains the leading cause of death in this population. The development and progression of CVD-compared to the general population-is premature and accelerated, manifesting as coronary artery disease, heart failure, arrhythmias, and sudden cardiac death. CKD and CV disease combine to cause multimorbid cardiorenal syndrome (CRS) due to contributions from shared risk factors, including systolic hypertension, diabetes mellitus, obesity, and dyslipidemia. Additional neurohormonal activation, innate immunity, and inflammation contribute to progressive cardiac and renal deterioration, reflecting the strong bidirectional interaction between these organ systems. A shared molecular pathophysiology-including inflammation, oxidative stress, senescence, and hemodynamic fluctuations characterise all types of CRS. This review highlights the evolving paradigm and recent advances in our understanding of the molecular biology of CRS, outlining the potential for disease-specific therapies and biomarker disease detection.

The Distinct Regulation of the Vitamin D and Aryl Hydrocarbon Receptors in COVID-19

(1) Background: SARS-CoV-2 affects several immune pathways, including the vitamin D (VDR) and the aryl hydrocarbon receptor pathways (AhR). The aim of the study was the evaluation of the VDR and AhR pathways in the blood of COVID-19 patients with regard to the severity of disease. (2) Methods: Observational, single-center, case-control design. A total of 240 samples were selected for exploration. Patients who tested negative for SARS-CoV-2 but suffered from other respiratory infections (ORIs) served as a control group. (3) Results: VDR-specific mRNA in the blood of patients with mild symptoms (131.2 ± 198.6) was significantly upregulated relative to the VDR expression of the ORI group (23.24 ± 42.60; p < 0.0001); however, VDR expression of critically ill patients showed an impaired upregulation (54.73 ± 68.34; p < 0.001). CYP27B1 expression was not significantly regulated during SARS-CoV-2 infection. There was a downregulation of VDR and CYP27B1 compared to survivors. There was no significant difference in 25(OH)-vitamin D3 levels between critically ill patients with regard to survival (24.3 ± 9.4 vs. 27.1 ± 11.3; p = 0.433). (4) Conclusion: The VDR and AhR pathways are distinctively regulated in patients suffering from COVID-19 depending on the severity of disease. A combination treatment of antiviral drugs and vitamin D substitution should be evaluated for potentially improved prognosis in COVID-19.

Sex-dependent effects of chronic intermittent hypoxia: Implication for obstructive sleep apnea

Background Obstructive sleep apnea (OSA) affects 10-26% of adults in the United States with known sex differences in prevalence and severity. OSA is characterized by elevated inflammation, oxidative stress (OS), and cognitive dysfunction. However, there is a paucity of data regarding the role of sex in the OSA phenotype. Prior findings suggest women exhibit different OSA phenotypes than men, which could result in under-reported OSA prevalence in women. To examine the relationship between OSA and sex, we used chronic intermittent hypoxia (CIH) to model OSA in rats. We hypothesized that CIH would produce sex-dependent phenotypes of inflammation, OS, and cognitive dysfunction, and these sex differences would be dependent on mitochondrial oxidative stress (mtOS). Methods Adult male and female Sprague Dawley rats were exposed to CIH or normoxia for 14 days to examine the impact of sex on CIH-associated circulating inflammation (IL-1β, IL-4, IL-6, IL-10, TNF-α), circulating OS, and behavior (recollective and spatial memory; gross and fine motor function; anxiety-like behaviors; and compulsive behaviors). A subset of rats was implanted with osmotic minipumps containing either a mitochondria-targeting antioxidant (MitoTEMPOL) or saline vehicle 1 week prior to CIH initiation to examine how inhibiting mtOS would affect the CIH phenotype. Results Sex-specific differences in CIH-induced inflammation, OS, motor function, and compulsive behavior were observed. In female rats, CIH increased inflammation (plasma IL-6 and IL-6/IL-10 ratio) and impaired fine motor function. Conversely, CIH elevated circulating OS and compulsivity in males. These sex-dependent effects of CIH were blocked by inhibiting mtOS. Interestingly, CIH impaired recollective memory in both sexes but these effects were not mediated by mtOS. No effects of CIH were observed on spatial memory, gross motor function, or anxiety-like behavior, regardless of sex. Conclusions Our results indicate that the impact of CIH is dependent on sex, such as an inflammatory response and OS response in females and males, respectively, that are mediated by mtOS. Interestingly, there was no effect of sex or mtOS in CIH-induced impairment of recollective memory. These results indicate that mtOS is involved in the sex differences observed in CIH, but a different mechanism underlies CIH-induced memory impairments.