Sexual dimorphism of monocyte transcriptome in individuals with chronic low-grade inflammation

Cellular and biochemical heterogeneity contributes to the phenotypic diversity of transfusion-dependent β-thalassemia

ABSTRACT

Transfusion-dependent thalassemia (TDT) is a type of protein aggregation disease. Its clinical heterogeneity imposes challenges in effective management. Red blood cell (RBC) variables may be clinically relevant as mechanistic parts or tellers of TDT pathophysiology. This is a cross-sectional study of RBC and plasma physiology in adult patients with TDT vs healthy control. TDT plasma was characterized by increased protein carbonylation, antioxidants, and larger than normal extracellular vesicles. RBCs were osmotically resistant but prone to oxidative hemolysis. They overexposed phosphatidylserine and exhibited pathologically low proteasome proteolytic activity (PPA), which correlated with metabolic markers of the disease. RBC ultrastructure was distorted, with splenectomy-related membrane pits of 300 to 800 nm. Plasma metabolomics revealed differences in heme metabolism, redox potential, short-chain fatty acids, and nitric oxide bioavailability, but also in catecholamine pathways. According to coefficient of variation assessment, hemolysis, iron homeostasis, PPA, and phosphatidylserine exposure were highly variable among patients, as opposed to RBC fragility and plasma antioxidants, amino acids, and catecholamines. Sex-based differences were detected in hemolysis, redox, and energy variables, whereas splenectomy-related differences referred to thrombotic risk, RBC morphology, and plasma metabolites with neuroendocrine activity. Hepcidin varied according to oxidative hemolysis and metabolic markers of bacterial activity. Patients with higher pretransfusion hemoglobin levels (>10 g/dL) presented mildly distorted profiles and lower membrane-associated PPA, whereas classification by severity of mutations revealed different levels of hemostasis, inflammation, plasma epinephrine, hexosamines, and methyltransferase activity markers. The currently reported heterogeneity of cellular and biochemical features probably contributes to the wide phenotypic diversity of TDT at clinical level.

A sex-specific anti-inflammatory role for p62 in psoriasis-like disease

Psoriasis (Ps) is a chronic inflammatory skin disease involving a complex cross talk between immune and epidermal cells. Ps is difficult to treat and often complicated by systemic manifestations such as psoriatic arthritis (PsA). Sequestosome 1/p62 is a multifunctional adaptor protein controlling autophagy, cell differentiation and inflammation that was found elevated in human psoriatic skin. We functionally evaluated the role of p62 in the cutaneous and systemic Ps-like phenotypes of a mouse model with inducible epidermal inactivation of c-Jun and JunB (DKO*). A male-specific aggravation of skin and joint disease was observed in DKO* mice, when crossed to p62-/- mice (DKO* p62-/-). Thickened epidermis, disturbed keratinocyte differentiation, enhanced immune cell infiltration and increased Cxcl1 expression were exclusively observed in the skin of male DKO* p62-/- mice. Increased androgen receptor (AR) protein expression and activation of AR signaling, as well as upregulated inflammasome and Keap1/Nrf2 activities were apparent in the skin of male DKO* p62-/- mice and are likely responsible for disease worsening. Our results describe a sex-specific anti-inflammatory role for p62 in Ps-like disease that could be relevant in the clinical setting.

Monocyte eukaryotic initiation factor 2 signaling differentiates 17-hydroxy-docosahexaenoic acid levels and pain

Our goal was to probe the potential transcriptomic basis for the relationship between plasma levels of the specialized pro-resolving precursor, 17-hydroxy-docosahexaenoic acid (17-HDHA) and chronic pain. Participants with osteoarthritis (average age of 62.3, 60% were female, n = 30) were stratified by levels of 17-HDHA and self-reported pain scores. RNAs from CD14++/CD16-/CD66b-/HLA-DR+ (classical) monocytes were sequenced and differentially expressed mRNAs were identified with DESeq2. QIAGEN ingenuity pathway analysis identified the top ranked canonical biological pathway to be eukaryotic initiation factor 2 (EIF2) signaling (lower activation level in the low 17-HDHA-high pain group compared to the high 17-HDHA-low pain group (Z score -3)), followed by EIF4 and P70S6K signaling pathways and mTOR signaling. Our approach provides insight into the biological pathways contributing to the association between 17-HDHA and chronic osteoarthritis (OA) pain, identifying EIF2 signaling, with known roles in osteoclast differentiation, OA pathology, and pain, as a potential downstream target.

Sexual dimorphism in immunity and longevity among the oldest old

Human longevity is a sex-biased process in which sex chromosomes and sex-specific immunity may play a crucial role in the health and lifespan disparities between men and women. Generally, women have a higher life expectancy than men, exhibiting lower infection rates for a broad range of pathogens, which results in a higher prevalence of female centenarians compared to males. Investigation of the immunological changes that occur during the process of healthy aging, while taking into account the differences between sexes, can significantly enhance our understanding of the mechanisms that underlie longevity. In this review, we aim to summarize the current knowledge on sexual dimorphism in the human immune system and gut microbiome during aging, with a particular focus on centenarians, based exclusively on human data.

Association of smoking with neurocognition, inflammatory and myeloid cell activation profiles in people with HIV on antiretroviral therapy

OBJECTIVE

People with HIV (PWH) experience excess comorbidities, including neurocognitive disorders, which are linked to inflammation, particularly monocyte-macrophage activation. Smoking contributes to morbidity and mortality in well treated PWH. We investigated associations between smoking, neurocognitive function, and inflammation in PWH on antiretroviral therapy (ART).

DESIGN

We used baseline data on cognition and inflammation from a longitudinal study of virologically suppressed PWH who do and do not smoke.

METHODS

Participants completed four neurocognitive tests (seven measures), with a composite score as the primary measure. Inflammatory markers were plasma sCD14, sCD163, and CCL2/MCP-1; %CD14 + monocytes expressing CD16, CD163, and CCR2; and %CD8 + T cells co-expressing CD38/HLA-DR. Exploratory analyses included a plasma cytokine/chemokine panel, neurofilament light chain (NFL), hsCRP, and monocyte transcriptomes by RNAseq.

RESULTS

We recruited 58 PWH [26 current smoking (PWH/S), 32 no current smoking (PWH/NS)]. Mean composite and individual neurocognitive scores did not differ significantly by smoking status except for the color shape task; PWH/S exhibited worse cognitive flexibility, with adjusted mean times 317.2 [95% confidence interval (CI) 1.4-632.9] ms longer than PWH/NS. PWH/S had higher plasma sCD14 than PWH/NS [median (IQR) 1820 (1678-2105) vs. 1551 (1284-1760) ng/ml, P  = 0.009]. Other inflammatory markers were not significantly different between PWH/S and PWH/NS. Monocyte transcriptomes showed several functions, regulators, and gene-sets that differed by smoking status.

CONCLUSION

sCD14, a marker of monocyte activation, is elevated in PWH who smoke. Although neurocognitive measures and other inflammatory markers did not generally differ, these data implicate smoking-related myeloid activation and monocyte gene dysregulation in the HIV/smoking synergy driving HIV-associated comorbidities.

Human monocyte subtype expression of neuroinflammation- and regeneration-related genes is linked to age and sex

Aging profoundly affects the immune system leading to an increased propensity for inflammation. Age-related dysregulation of immune cells is implicated in the development and progression of numerous age-related diseases such as: cardiovascular diseases, neurodegenerative disorders, and metabolic syndromes. Monocytes and monocyte-derived macrophages, being important players in the inflammatory response, significantly influence the aging process and the associated increase in inflammatory disease risk. Ischemic stroke is among age-related diseases where inflammation, particularly monocyte-derived macrophages, plays an important deteriorating role but could also strongly promote post-stroke recovery. Also, biological sex influences the incidence, presentation, and outcomes of ischemic stroke, reflecting both biological differences between men and women. Here, we studied whether human peripheral blood monocyte subtype (classical, intermediate, and non-classical) expression of genes implicated in stroke-related inflammation and post-stroke tissue regeneration depends on age and sex. A flow cytometry analysis of blood samples from 44 healthy volunteers (male and female, aged 28 to 98) showed that in contrast to other immune cells, the proportion of NK-cells increased in females. The proportion of B-cells decreased in both sexes with age. Gene expression analysis by qPCR identified several genes differentially correlating with age and sex within different monocyte subtypes. Interestingly, ANXA1 and CD36 showed a consistent increase with aging in all monocytes, specifically in intermediate (CD36) and intermediate and non-classical (ANXA1) subtypes. Other genes (IL-1β, S100A8, TNFα, CD64, CD33, TGFβ1, TLR8, CD91) were differentially changed in monocyte subtypes with increasing age. Most age-dependent gene changes were differentially expressed in female monocytes. Our data shed light on the nuanced interplay of age and sex in shaping the expression of inflammation- and regeneration-related genes within distinct monocyte subtypes. Understanding these dynamics could pave the way for targeted interventions and personalized approaches in post-stroke care, particularly for the aging population and individuals of different sexes.

UBA1 dysfunction in VEXAS and cancer

UBA1, an X-linked gene, encodes one of the only two ubiquitin E1 enzymes, playing a pivotal role in initiating one of the most essential post-translational modifications. In late 2020, partial loss-of-function mutations in UBA1 within hematopoietic stem and progenitor cells were found to be responsible for VEXAS Syndrome, a previously unidentified hematoinflammatory disorder predominantly affecting older males. The condition is characterized by severe inflammation, cytopenias, and an association to hematologic malignancies. In this research perspective, we comprehensively review the molecular significance of UBA1 loss of function as well as advancements in VEXAS research over the past four years for each of the VEXAS manifestations - inflammation, cytopenias, clonality, and possible oncogenicity. Special attention is given to contrasting the M41 and non-M41 mutations, aiming to elucidate their differential effects and to identify targetable mechanisms responsible for each of the symptoms. Finally, we explore the therapeutic landscape for VEXAS Syndrome, discussing the efficacy and potential of clone-targeting drugs based on the pathobiology of VEXAS. This includes azacitidine, currently approved for myelodysplastic neoplasms (MDS), novel UBA1 inhibitors being developed for a broad spectrum of cancers, Protein Kinase R-like Endoplasmic Reticulum Kinase (PERK) inhibitors, and auranofin, a long-established drug for rheumatoid arthritis. This perspective bridges basic research to clinical symptoms and therapeutics.

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.

Microheterogeneity in the Kinetics and Sex-Specific Response to Type I IFN

The response to type I IFNs involves the rapid induction of prototypical IFN signature genes (ISGs). It is not known whether the tightly controlled ISG expression observed at the cell population level correctly represents the coherent responses of individual cells or whether it masks some heterogeneity in gene modules and/or responding cells. We performed a time-resolved single-cell analysis of the first 3 h after in vivo IFN stimulation in macrophages and CD4+ T and B lymphocytes from mice. All ISGs were generally induced in concert, with no clear cluster of faster- or slower-responding ISGs. Response kinetics differed between cell types: mostly homogeneous for macrophages, but with far more kinetic diversity among B and T lymphocytes, which included a distinct subset of nonresponsive cells. Velocity analysis confirmed the differences between macrophages in which the response progressed throughout the full 3 h, versus B and T lymphocytes in which it was rapidly curtailed by negative feedback and revealed differences in transcription rates between the lineages. In all cell types, female cells responded faster than their male counterparts. The ISG response thus seems to proceed as a homogeneous gene block, but with kinetics that vary between immune cell types and with sex differences that might underlie differential outcomes of viral infections.

Adenosine, lidocaine, and magnesium therapy augments joint tissue healing following experimental anterior cruciate ligament rupture and reconstruction

Aims

Adenosine, lidocaine, and Mg2+ (ALM) therapy exerts differential immuno-inflammatory responses in males and females early after anterior cruciate ligament (ACL) reconstruction (ACLR). Our aim was to investigate sex-specific effects of ALM therapy on joint tissue repair and recovery 28 days after surgery.

Methods

Male (n = 21) and female (n = 21) adult Sprague-Dawley rats were randomly divided into ALM or Saline control treatment groups. Three days after ACL rupture, animals underwent ACLR. An ALM or saline intravenous infusion was commenced prior to skin incision, and continued for one hour. An intra-articular bolus of ALM or saline was also administered prior to skin closure. Animals were monitored to 28 days, and joint function, pain, inflammatory markers, histopathology, and tissue repair markers were assessed.

Results

Despite comparable knee function, ALM-treated males had reduced systemic inflammation, synovial fluid angiogenic and pro-inflammatory mediators, synovitis, and fat pad fibrotic changes, compared to controls. Within the ACL graft, ALM-treated males had increased expression of tissue repair markers, decreased inflammation, increased collagen organization, and improved graft-bone healing. In contrast to males, females had no evidence of persistent systemic inflammation. Compared to controls, ALM-treated females had improved knee extension, gait biomechanics, and elevated synovial macrophage inflammatory protein-1 alpha (MIP-1α). Within the ACL graft, ALM-treated females had decreased inflammation, increased collagen organization, and improved graft-bone healing. In articular cartilage of ALM-treated animals, matrix metalloproteinase (MMP)-13 expression was blunted in males, while in females repair markers were increased.

Conclusion

At 28 days, ALM therapy reduces inflammation, augments tissue repair patterns, and improves joint function in a sex-specific manner. The study supports transition to human safety trials.

Sex differences in lipid mediators derived from omega-3 fatty acids in older individuals with low-grade chronic inflammation

The rate of cardiovascular disease (CVD) death is higher in men than women before age 50 y, but the gap between sexes significantly narrows after menopause. Lipid mediators derived from EPA, DHA and AA play a role in inflammation and CVD. The aim of our study was to assess whether plasma concentrations of these lipid mediators differ between postmenopausal women and men. Twelve postmenopausal women and 9 men with low-grade chronic inflammation completed a randomized, double-blind, crossover study consisting of a 4-week lead-in placebo phase (3 g/d high-oleic acid sunflower oil) followed by randomization to either 3 g/d DHA or 3 g/d EPA for 10 weeks and crossover for additional 10 weeks, separated by a washout phase. Plasma phospholipid content of EPA, DHA and AA and plasma concentrations of their derived lipid mediators were measured at the end of the placebo lead-in phase (baseline) and the DHA and EPA supplementation phases. There were no sex differences in plasma phospholipid EPA, DHA and AA at baseline and after DHA and EPA supplementation. However, plasma concentrations of lipid mediators derived from EPA, DHA and AA via 15-lipoxygenase were lower in postmenopausal women than men, especially after supplementation. Sex differences in EPA- and DHA-derived lipid mediators with anti-inflammatory and pro-resolving actions may partly explain the faster rise in CVD in postmenopausal women than age-matched men.

Human monocyte subtype expression of neuroinflammation and regeneration-related genes is linked to age and sex

Stroke is a leading cause of disability and the third cause of death. The immune system plays an essential role in post-stroke recovery. After an ischemic stroke, monocytes infiltrate the injured brain tissue and can exacerbate or mitigate the damage. Ischemic stroke is more prevalent in the aged population, and the aging brain exhibits an altered immune response. There are also sex disparities in ischemic stroke incidence, outcomes, and recovery, and these differences may be hormone-driven and determined by genetic and epigenetic factors. Here, we studied whether human peripheral blood monocyte subtype (classical, intermediate, and non-classical) expression of neuronal inflammation- and regeneration-related genes depends on age and sex. A FACS analysis of blood samples from 44 volunteers (male and female, aged 28 to 98) showed that in contrast to other immune cells, the proportion of natural killer cells increased in females. The proportion of B-cells decreased in both sexes with age, and subtypes of monocytes were not linked to age or sex. Gene expression analysis by qPCR identified several genes differentially correlating with age and sex within different monocyte subtypes. Interestingly, ANXA1 and CD36 showed a consistent increase with aging in all monocytes, specifically in intermediate (CD36) and intermediate and non-classical (ANXA1) subtypes. Other genes (IL-1β, S100A8, TNFα, CD64, CD33, TGFβ1, TLR8, CD91) were differentially changed in monocyte subtypes with increased aging. Most age-dependent gene changes were differentially expressed in female monocytes. Our data shed light on the nuanced interplay of age and sex in shaping the expression of inflammation- and regeneration-related genes within distinct monocyte subtypes. Understanding these dynamics could pave the way for targeted interventions and personalized approaches in post-stroke care, particularly for the aging population and individuals of different sexes.

Monocyte transcriptomic profile following EPA and DHA supplementation in men and women with low-grade chronic inflammation

BACKGROUND

Recent data indicate considerable variability in response to very long chain omega-3 fatty acid supplementation on cardiovascular disease risk. This inconsistency may be due to differential effects of EPA vs DHA and/or sex-specific responses.

METHODS

Sixteen subjects (eight men and eight women) 50-75 y and with low-grade chronic inflammation participated in a randomized controlled crossover trial comparing 3 g/d EPA, 3 g/d DHA, and placebo (3 g/d high oleic acid sunflower oil). Blood monocytes were isolated at the end of each phase for RNA-sequencing.

RESULTS

Sex dimorphism in monocyte gene expression was observed, therefore, data for men and women were analyzed separately. 1088 genes were differentially expressed in men and 997 in women (p < 0.05). In both men and women, EPA and DHA repressed genes involved in protein turnover and mitochondrial energy metabolism, relative to placebo. In men only, EPA and DHA upregulated genes related to wound healing and PPARα activation. In women only, EPA and DHA activated genes related to ER stress response. Relative to DHA, EPA resulted in lower expression of genes involved in inflammatory processes in men, and lower expression of genes involved in ER stress response in women.

CONCLUSIONS

EPA and DHA supplementation elicited both similar and differential effects on monocyte transcriptome, some of which were sex specific. The observed variability in response to EPA and DHA in men and women could in part explain the conflicting results from previous cardiovascular clinical trials using omega-3 fatty acids.

Gene expression profiling of monocytes in recent-onset schizophrenia

Immune-related mechanisms have been suggested to be involved in schizophrenia. Various studies have shown changes in monocytes isolated from the blood of schizophrenia patients, including changes in monocyte numbers, as well as altered protein and transcript levels of important markers. However, validation of these findings and understanding how these results are related to immune-related changes in the brain and schizophrenia genetic risk factors, is limited. The goal of this study was to better understand changes observed in monocytes of patients with early-onset schizophrenia. Using RNA sequencing, we analyzed gene expression profiles of monocytes isolated from twenty patients with early-onset schizophrenia and seventeen healthy controls. We validated expression changes of 7 out of 29 genes that were differentially expressed in previous studies including TNFAIP3, DUSP2, and IL6. At a transcriptome-wide level, we found 99 differentially expressed genes. Effect sizes of differentially expressed genes were moderately correlated with differential expression in brain tissue (Pearson's r = 0.49). Upregulated genes were enriched for genes in NF-κB and LPS signaling pathways. Downregulated genes were enriched for glucocorticoid response pathways. These pathways have been implicated in schizophrenia before and play a role in regulating the activation of myeloid cells. Interestingly, they are also involved in several non-inflammatory processes in the central nervous system, such as neurogenesis and neurotransmission. Future studies are needed to better understand how dysregulation of the NF-κB and glucocorticoid pathways affects inflammatory and non-inflammatory processes in schizophrenia. The fact that dysregulation of these pathways is also seen in brain tissue, provides potential possibilities for biomarker development.

Sex differences in the inflammatory response to stroke

Ischemic stroke is a leading cause of morbidity and mortality and disproportionally affects women, in part due to their higher longevity. Older women have poorer outcomes after stroke with high rates of cognitive deficits, depression, and reduced quality of life. Post-stroke inflammatory responses are also sexually dimorphic and drive differences in infarct size and recovery. Factors that influence sex-specific immune responses can be both intrinsic and extrinsic. Differences in gonadal hormone exposure, sex chromosome compliment, and environmental/social factors can drive changes in transcriptional and metabolic profiles. In addition, how these variables interact, changes across the lifespan. After the onset of ischemic injury, necrosis and apoptosis occur, which activate microglia and other glial cells within the central nervous system, promoting the release of cytokines and chemokines and neuroinflammation. Cells involved in innate and adaptive immune responses also have dual functions after stroke as they can enhance inflammation acutely, but also contribute to suppression of the inflammatory cascade and later repair. In this review, we provide an overview of the current literature on sex-specific inflammatory responses to ischemic stroke. Understanding these differences is critical to identifying therapeutic options for both men and women.

Monocyte-derived Dll4 is a novel contributor to persistent systemic inflammation in HIV patients

Background

In people living with HIV (PLWH) on combination antiretroviral therapy (cART), persistent systemic inflammation is a driving force for the progression of comorbidities, such as cardiovascular and cerebrovascular diseases. In this context, monocyte- and macrophage-related inflammation rather than T cell activation is a major cause of chronic inflammation. However, the underlying mechanism of how monocytes cause persistent systemic inflammation in PLWH is elusive.

Methods and Results

In vitro, we demonstrated that lipopolysaccharides (LPS) or tumor necrosis factor alpha (TNFα), induced a robust increase of Delta-like ligand 4 (Dll4) mRNA and protein expression in human monocytes and Dll4 secretion (extracellular Dll4, exDll4) from monocytes. Enhanced membrane-bound Dll4 (mDll4) expression in monocytes triggered Notch1 activation to promote pro-inflammatory factors expression. Dll4 silencing and inhibition of Nocth1 activation diminished the LPS or TNFα -induced inflammation. exDll4 releases in response to cytokines occurred in monocytes but not endothelial cells or T cells. In clinical specimens, we found that PLWH, both male and female, on cART, showed a significant increase in mDll4 expression, activation of Dll4-Notch1 signaling, and inflammatory markers in monocytes. Although there was no sex effect on mDII4 in PLWH, plasma exDll4 was significantly elevated in males but not females compared to HIV uninfected individuals. Furthermore, exDll4 plasma levels paralleled with monocytes mDll4 in male PLWH. Circulating exDll4 was also positively associated with pro-inflammatory monocytes phenotype and negatively associated with classic monocytes phenotype in male PLWH.

Conclusion

Pro-inflammatory stimuli increase Dll4 expression and Dll4-Notch1 signaling activation in monocytes and enhance monocyte proinflammatory phenotype, contributing to persistent systemic inflammation in male and female PLWH. Therefore, monocyte mDll4 could be a potential biomarker and therapeutic target of systemic inflammation. Plasma exDll4 may also play an additional role in systemic inflammation but primarily in men.

Sex differences in Guillain Barré syndrome, chronic inflammatory demyelinating polyradiculoneuropathy and experimental autoimmune neuritis

Guillain Barré syndrome (GBS) and its variants, and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP and its variants, are regarded as immune mediated neuropathies. Unlike in many autoimmune disorders, GBS and CIDP are more common in males than females. Sex is not a clear predictor of outcome. Experimental autoimmune neuritis (EAN) is an animal model of these diseases, but there are no studies of the effects of sex in EAN. The pathogenesis of GBS and CIDP involves immune response to non-protein antigens, antigen presentation through non-conventional T cells and, in CIDP with nodopathy, IgG4 antibody responses to antigens. There are some reported sex differences in some of these elements of the immune system and we speculate that these sex differences could contribute to the male predominance of these diseases, and suggest that sex differences in peripheral nerves is a topic worthy of further study.

Sex dimorphism in the tumor microenvironment - From bench to bedside and back

Cancer represents a significant cause of death and suffering in both the developed and developing countries. Key underlying issues in the mortality of cancer are delayed diagnosis and resistance to treatments. However, improvements in biomarkers represent one important step that can be taken for alleviating the suffering caused by malignancy. Precision-based medicine is promising for revolutionizing diagnostic and treatment strategies for cancer patients worldwide. Contemporary methods, including various omics and systems biology approaches, as well as advanced digital imaging and artificial intelligence, allow more accurate assessment of tumor characteristics at the patient level. As a result, treatment strategies can be specifically tailored and adapted for individual and/or groups of patients that carry certain tumor characteristics. This includes immunotherapy, which is based on characterization of the immunosuppressive tumor microenvironment (TME) and, more specifically, the presence and activity of immune cell subsets. Unfortunately, while it is increasingly clear that gender strongly affects immune regulation and response, there is a knowledge gap concerning differences in sex-specific immune responses and how these contribute to the immunosuppressive TME and the response to immunotherapy. In fact, sex dimorphism is poorly understood in cancer progression and is typically ignored in current clinical practice. In this review, we aim to survey the available literature and highlight the existing knowledge gap in order to encourage further studies that would contribute to understanding both gender-biased immunosuppression in the TME and the driver of tumor progression towards invasive and metastatic disease. The review highlights the need to include sex optimized/genderized medicine as a new concept in future medicine cancer diagnostics and treatments.

Alzheimer's disease-related transcriptional sex differences in myeloid cells

Sex differences have been identified in many diseases associated with dysregulated immune responses, including Alzheimer's disease (AD), for which approximately two-thirds of patients are women. An accumulating body of research indicates that microglia may play a causal role in the pathogenesis of this disease. We hypothesised that sex differences in the transcriptome of human myeloid cells may contribute to the sex difference observed in AD prevalence. To explore this, we assessed bulk and single-nuclear RNA sequencing data sets generated from four human derived myeloid cell populations: post-mortem microglial nuclei, peripheral monocytes, monocyte-derived macrophages (MDMs) and induced pluripotent stem cell derived microglial-like cells (MGLs). We found that expression of AD risk genes, gene signatures associated with the inflammatory response in AD, and genes related to proinflammatory immune responses were enriched in microglial nuclei isolated from aged female donors without ante-mortem neurological disease, relative to those from males. In addition, these inflammation-associated gene sets were found to be enriched in peripheral monocytes isolated from postmenopausal women and in MDMs obtained from premenopausal individuals relative to age-matched males. Expression of these gene sets did not differ in MDMs derived from women whose blood was sampled across the menstrual cycle or in MGLs cultured with 17β-oestradiol. This suggests that the observed gene set enrichments in myeloid cells from women were not being driven by acute hormonal influences. Together, these data support the hypothesis that the increased prevalence of AD in women may be partly explained by a myeloid cell phenotype biased towards expression of biological processes relevant to AD.

Sex-Biased Control of Inflammation and Metabolism by a Mitochondrial Nod-Like Receptor

Mitochondria regulate steroid hormone synthesis, and in turn sex hormones regulate mitochondrial function for maintaining cellular homeostasis and controlling inflammation. This crosstalk can explain sex differences observed in several pathologies such as in metabolic or inflammatory disorders. Nod-like receptor X1 (NLRX1) is a mitochondria-associated innate receptor that could modulate metabolic functions and attenuates inflammatory responses. Here, we showed that in an infectious model with the human protozoan parasite, Leishmania guyanensis, NLRX1 attenuated inflammation in females but not in male mice. Analysis of infected female and male bone marrow derived macrophages showed both sex- and genotype-specific differences in both inflammatory and metabolic profiles with increased type I interferon production, mitochondrial respiration, and glycolytic rate in Nlrx1-deficient female BMDMs in comparison to wild-type cells, while no differences were observed between males. Transcriptomics of female and male BMDMs revealed an altered steroid hormone signaling in Nlrx1-deficient cells, and a “masculinization” of Nlrx1-deficient female BMDMs. Thus, our findings suggest that NLRX1 prevents uncontrolled inflammation and metabolism in females and therefore may contribute to the sex differences observed in infectious and inflammatory diseases.

Monocyte Trafficking and Polarization Contribute to Sex Differences in Meta-Inflammation

Obesity is associated with systemic inflammation and immune cell recruitment to metabolic tissues. Sex differences have been observed where male mice challenged with high fat diet (HFD) exhibit greater adipose tissue inflammation than females demonstrating a role for sex hormones in differential inflammatory responses. Circulating monocytes that respond to dietary lipids and chemokines and produce cytokines are the primary source of recruited adipose tissue macrophages (ATMs). In this study, we investigated sexual dimorphism in biological pathways in HFD-fed ATMs from male and female mice by RNA-seq. We also conducted chemotaxis assays to investigate sex differences in the migration of monocytes isolated from bone marrow from male and female mice toward a dietary saturated lipid - palmitate (PA), and a chemokine - monocyte chemoattractant protein 1 (MCP1), factors known to stimulate myeloid cells in obesity. ATM RNA-Seq demonstrated sex differences of both metabolic and inflammatory activation, including pathways for chemokine signaling and leukocyte trans-endothelial migration. In vivo monocyte transfer studies demonstrated that male monocytes traffic to female adipose tissue to generate ATMs more readily. In chemotaxis assays, lean male monocytes migrated in greater numbers than females toward PA and MCP1. With short-term HFD, male and female monocytes migrated similarly, but in chronic HFD, male monocytes showed greater migration than females upon PA and MCP1 stimulation. Studies with monocytes from toll-like receptor 4 knockout mice (Tlr4^-/- ) demonstrated that both males and females showed decreased migration than WT in response to PA and MCP1 implying a role for TLR4 in monocyte influx in response to meta-inflammation. Overall, these data demonstrate the role of sexual dimorphism in monocyte recruitment and response to metabolic stimuli that may influence meta-inflammation in obesity.