Influence of X chromosome in sex-biased autoimmune diseases

Comorbidities Are Associated With Unfavorable Outcome in Aquaporin-4 Antibody Positive Neuromyelitis Optica Spectrum Disorders and Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease: Exploratory Study From the CROCTINO Cohort

BACKGROUND

Comorbidities occur in aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder (AQP4-NMOSD), myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), and double seronegative NMOSD (DN-NMOSD), potentially contributing to a less favorable disease course.

OBJECTIVES

To characterize comorbidities in AQP4-NMOSD, MOGAD, and DN-NMOSD and assess their association with optic neuritis (ON) outcomes by optical coherence tomography (OCT) in AQP4-NMOSD.

METHODS

Four hundred and forty-two participants from the CROCTINO cohort were evaluated for comorbidities.

RESULTS

In AQP4-NMOSD patients (n = 360), 43.5% (n = 161) had comorbidities, equally divided between single and multiple. In MOGAD (n = 49), 40.8% had comorbidities, with 75% (n = 15) single and 25% (n = 5) multiple. In DN-NMOSD (n = 33), 36.4% (n = 12) had comorbidities equally split. AQP4-NMOSD patients had more multiple comorbidities (50%, n = 81/161) than MOGAD (25%, n = 5/20, p = 0.03) and more autoimmune disorders (AID) (40.4%, n = 65) than MOGAD (20%, n = 4, p = 0.09) and DN-NMOSD (none, p = 0.004). Cardiovascular comorbidities and related risk factors (CVC/RF) occurred in 34.8% (n = 56) of AQP4-NMOSD, 50% (n = 10) of MOGAD, and 33.3% (n = 4) of DN-NMOSD. Expanded Disability Status Scale was higher in MOGAD (3.0 vs. 2.0, p = 0.006) and DN-NMOSD (5.0 vs. 2.0, p = 0.008) with comorbidities. AQP4-NMOSD patients with CVC/RF had higher ON relapse rates than those with AID (1.06 ± 3.33 vs. 0.49 ± 0.98, p < 0.001). OCT revealed reduced inner nuclear layer thickness in AQP4-NMOSD with comorbidities compared to non-comorbidity (B = -1.52, p = 0.047), more pronounced with CVC/RF (B = -2.96, p = 0.009).

CONCLUSION

Comorbidities are frequent in AQP4-NMOSD and MOGAD and are associated with ON frequency and disability. These findings highlight the need for proactive comorbidity management to improve patient care.

Current anti-inflammatory strategies for treatment of heart failure: From innate to adaptive immunity

Cardiovascular disease (CVD) is the leading cause of death in developed countries worldwide, often manifesting in the form of heart failure (HF). Recent successful clinical outcomes of anti-inflammatory therapies in HF patients have greatly boosted interest in basic and translational research on the role of inflammation in development of HF. In this review, we discuss recent and ongoing therapies targeting inflammation in CVD/HF, including broad-spectrum anti-inflammatory drugs, supplements, and biologicals such as canakinumab and anakinra. We also discuss the growing body of literature supporting off-target/anti-inflammatory actions of mainline CVD/HF agents, including guideline-directed medical therapy (GDMT) drugs that target the neurohormonal axis, and statins. We discuss therapeutics that target autoimmune mechanisms, and their implications for treating patients with autoimmune diseases with HF or at-risk of developing HF. We also discuss recent evidence for vaccines in modulating the immune response during HF. We conclude that despite the wealth of knowledge gained in the past decade, the therapeutic efficacy of anti-inflammatory therapy is driven by many biological and logistical factors that vary from patient to patient. Furthermore, more studies are needed to understand the adaptive/autoimmune component of HF, particularly in women and patients with pre-existing autoimmune disease. As the number of patients with HF patients who suffer from obesity, diabetes, or autoimmune disease continues to grow, our understanding of inflammation must continue to evolve to reflect these underlying co-morbidities.

MicroRNA signatures of CD4+ T cell subsets in healthy and multiple sclerosis subjects determined by small RNA-sequencing

Diverse CD4+ T cell subsets with specialized functions operate at different phases of the immune response. Among these are phenotypically and functionally characterized naïve, central memory (CM), effector memory (EM), and regulatory (Treg) cells. Using small RNA-sequencing, we have profiled miRNAs in these cell subsets from healthy subjects and untreated patients with relapsing-remitting multiple sclerosis (RRMS). MiRNA genomic clustering and abundance were also investigated. From the 60 most differentially expressed miRNAs, broad and highly selective core signatures were determined for naïve and memory cells at homeostasis, while miR-146a-5p was strongly upregulated in Treg cells. In line with other studies, a 5-miRNA core was identified for naïve cells (miR-125b-5p, miR-99a-5p, miR-365a-3p, miR-365b-3p, miR-193b-3p). In memory cells, a number of identical miRNAs were more expressed in EM than CM cells, supporting the progressive T cell differentiation model. This was particularly the case for an 8-miRNA core (members from miR-23a∼27a∼24-2, miR-23b∼27b∼24-1, miR-221∼222 clusters, miR-22-3p, miR-181c-5p) and for the large ChrXq27.3 miR-506∼514 cluster. Interestingly, most of these miRNAs were reported to negatively regulate cell proliferation and survival. Finally, we found that the miRNA core signatures of naïve and memory CD4+ T cells were conserved in RRMS patients. Only few miRNAs were quantitatively modified and, among these, miR-1248 was validated to be downregulated in EM cells. Overall, this study expands and provides novel insights into miRNA profiling of CD4+ T cell subsets that may be useful for further investigations.

Might Thyroid Function in Patients with Turner Syndrome Have a Significant Impact on Their Muscle Strength?

Turner syndrome (TS) is a genetic disorder caused by abnormalities in one of the X chromosomes. Individuals with TS have a higher incidence of autoimmune thyroid disorders, particularly Hashimoto's disease, leading to thyroid dysfunction, most commonly hypothyroidism. Hormonal imbalance, growth hormone deficiency, and reduced physical activity contribute to muscle weakness in TS patients, and thyroid dysfunction can exacerbate these effects. The purpose of this study was to evaluate whether thyroid factors affect muscle strength in female patients with TS. The study included 70 women with TS and 88 age- and weight-matched controls. TS diagnoses were genetically confirmed (mosaic karyotypes: n = 20; monosomy X: n = 37; structural abnormalities: n = 7). The main criterion for exclusion from the study was unbalanced thyroid function. Serum levels of thyroid-stimulating hormone (TSH), free thyroxine (fT4), free triiodothyronine (fT3), and thyroid antibodies (anti-thyroid peroxidase antibodies (aTPO), anti-thyroglobulin antibodies (aTG)) were measured, and muscle strength was assessed using hand-held dynamometry. In TS patients, higher TSH levels were positively correlated, and higher fT4 levels were negatively correlated with muscle strength. No such correlations were found in controls. Thyroid compensation may impact musculoskeletal health in TS. Lower-normal TSH levels are associated with reduced muscle strength, and autoimmune thyroid changes like aTPO and aTG may contribute to muscle deterioration. Further research is needed to confirm these findings.

Deciphering Autoimmune Diseases: Unveiling the Diagnostic, Therapeutic, and Prognostic Potential of Immune Repertoire Sequencing

Autoimmune diseases (AIDs) are immune system disorders where the body exhibits an immune response to its own antigens, causing damage to its own tissues and organs. The pathogenesis of AIDs is incompletely understood. However, recent advances in immune repertoire sequencing (IR-seq) technology have opened-up a new avenue to study the IR. These studies have revealed the prevalence in IR alterations, potentially inducing AIDs by disrupting immune tolerance and thereby contributing to our comprehension of AIDs. IR-seq harbors significant potential for the clinical diagnosis, personalized treatment, and prognosis of AIDs. This article reviews the application and progress of IR-seq in diseases, such as multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis, and type 1 diabetes, to enhance our understanding of the pathogenesis of AIDs and offer valuable references for the diagnosis and treatment of AIDs.

Trends in nationwide incidence of uveitis in South Korea using the National Health Insurance claims database from 2010 to 2021

OBJECTIVES

To investigate the population-based incidence of uveitis and the differences between anterior and non-anterior uveitis using the comprehensive Korean National Health Insurance Service (NHIS) database.

METHODS

We extracted data of patients who visited the clinic and were diagnosed with uveitis (based on Korean Classification of Diseases) from 2010 to 2021. The incidence of uveitis, differences between the demographics, and the underlying co-morbidities of anterior uveitis, non-anterior uveitis, and control groups were investigated.

RESULTS

We identified 919,370 cases with uveitis (anterior: 800,132; non-anterior: 119,238). The average incidences (per 10,000 persons) of anterior and non-anterior uveitis were 13.0 (95% confidence interval [CI], 12.9-13.0), and 1.9 (95% CI, 1.9-1.9), respectively. The incidence increased (2010: 13.0; 2019: 16.5) but decreased during the coronavirus disease (COVID-19) pandemic (2020: 15.5; 2021: 15.4). The non-anterior group was significantly associated with sex (female, odds ratio [OR]: 1.09, p < 0.0001), specific age range (40-69 years, p < 0.0001), high Charlson Comorbidity Index (p < 0.0001), high household income (p < 0.0001), and various immunologic diseases (antiphospholipid antibody syndrome, OR: 1.79, p < 0.0001; systemic lupus erythematosus, OR: 1.22, p < 0.0001; psoriasis, OR: 1.13, p < 0.0001; ulcerative colitis, OR: 1.11, p = 0.0013; tuberculosis, OR: 1.09, p < 0.0001; rheumatoid arthritis, OR: 1.05, p < 0.0001) compared with the anterior group.

CONCLUSIONS

Using the NHIS database, we conducted the largest population-based epidemiological study on uveitis in South Korea to estimate its increasing incidence in the past decade (including changes during COVID-19 pandemic) as well as its anatomical distribution. Our results may be beneficial for estimating the national burden of uveitis.

Salt sensitivity of blood pressure: mechanisms and sex-specific differences

Salt sensitivity of blood pressure (SSBP) is an independent risk factor for cardiovascular disease in individuals with or without hypertension. However, the mechanisms and management of SSBP remain unclear, mainly because the diagnosis of this condition relies on salt loading-depletion protocols that are not feasible in the clinic. The prevalence of hypertension is lower in premenopausal women than in men, but this sex-specific difference is reversed after menopause. Whether excessive SSBP in women at any age contributes to this reversal is unknown, but many clinical studies that have rigorously assessed for SSBP using salt loading-depletion protocols have confirmed that SSBP is more prevalent in women than in men, including during premenopausal age. In this Review, we discuss sex-specific mechanisms of SSBP. We describe sex-related differences in renal transporters, hypertensive pregnancy, SSBP in autoimmune disorders and mitogen-activated protein kinase signalling pathways, and highlight limitations and lessons learned from Dahl salt-sensitive rat models.

The toll like receptor 7 pathway and the sex bias of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) predominately affects women with a ratio of females-to-males of about 9:1. The complement of sex chromosomes may play and important role in the mechanism of the sex bias. Previous work has shown that men with Klinefleter's syndrome (47,XXY) as well as women with 47,XXX are found in excess among SLE patients well as among Sjogren's disease, systemic sclerosis and idiopathic inflammatory myositis. in cells with more than one X chromosome, all but one is inactivated. However, X chromosome inactivation, as mediated by the long noncoding RNA X-inactive specific transcript, or XIST, is not complete with approximately 10% of genes in the non-recombining region of the X chromosome escaping X inactivation. In the TLR7 signaling pathway, both the TLR7 and TLR adaptor interacting with endolysosomal SLC15A4 (TASL) escape X inactivation. Comparing male and female immune cells, there is increased TLR7 signaling related to increased expression of these genes in cells with more than one X chromosome. Cells with more than one X chromosome also express XIST, while cells with one X chromosome do not. XIST, as a source of ligand for TLR7, has also been shown to increase TLR7 signaling. Thus, we propose that both these mechanisms operating in immune cells with more than one X chromosome may act in a mutual way to mediate an X chromosome dose effect for the sex bias of autoimmune disease.

Associations of Systemic Immune-Inflammation Index With Mortality Risk Among Adults in Diabetic Kidney Disease, NHANES 1999 to 2018

OBJECTIVES

Immune-inflammation plays a crucial role in the pathogenesis of diabetic kidney disease (DKD), but an exact assessment of indicators remains undefined. In this study we address the link between systemic immune-inflammation index (SII) and mortality risk in DKD, and we explore the effect of sex disparities.

METHODS

Data from patients with DKD from the National Health and Nutritional Examination Surveys (NHANES, 1999 to 2018) were studied and their causes of death were identified from NHANES-related files. A weighted Cox model was used to evaluate hazard ratios for all-cause, cardiovascular, and cardiocerebrovascular mortality, and these associations were visualized by smoothing curves.

RESULTS

The average SII was 634.20 (103/μL). There were 1,283 deaths recorded during 273,422 person months (396 were cardiovascular related and 461 were cardiocerebrovascular related). Higher SIIs in the fifth quintile were significantly associated with increased mortality (p<0.01). SII trends showed an increased risk of all-cause mortality of >697.0 (103/μL), cardiovascular risk of >717.8 (103/μL), and cardiocerebrovascular risk of >650.0 (103/μL). In men, mortality increased when SII reached 500 to 660 (103/μL) and 700 to 760 (103/μL) for women.

CONCLUSIONS

There was a significant association between higher SII and increased risk of all-cause, cardiovascular, and cardiocerebrovascular mortality in DKD patients. In addition, although men had lower SII, their mortality was higher than that of women.

Synergistic Effects of Extra X Chromosome on Development of Systemic Lupus Erythematosus and Sjögren Disease in Klinefelter and Triple X Syndrome: A Retrospective Cohort Study

OBJECTIVE

Systemic lupus erythematosus (SLE) and Sjögren disease (SjD) are autoimmune diseases with significant female predominance. The prevalence of SLE is increased in Klinefelter syndrome (KS) compared with the general male population. Our study investigates the dose effects of extra X chromosomes on the development of SLE and SjD in KS and triple X syndrome compared with the general population.

METHODS

This multicenter, retrospective cohort study used TriNetX, a global federated research database. Using International Statistical Classification of Diseases, Tenth Revision, Clinical Modification codes, patients with a diagnosis of SLE or SjD in the general population, as well as those with SLE and SjD in KS (karyotype 47,XXY) and triple X syndrome (karyotype 47,XXX) from January 1, 2010, to January 1, 2024, were identified. Fisher's exact test was used to calculate the relative risk of SLE and SjD in males with KS and females with triple X syndrome compared with the general population. The 95% confidence intervals (95% CI) were obtained with STATA statistical software.

RESULTS

A total of 113,748,373 patients were identified. The prevalence of SLE and SjD was 0.59% and 0.077%, respectively, in men, and 0.381% and 0.388% for SLE and SjD, respectively, in women. The male-to-female ratios for all ages were 1:6.4 for SLE and 1:5 for SjD. The prevalence of KS and triple X syndrome in the general population was 0.0017% and 0.0010%, respectively. Among patients with KS, the prevalence of SLE and SjD was both 0.5%. Among patients with triple X syndrome, the prevalence of SLE and SjD was 1.3% and 0.8%, respectively. SLE was 8.5-fold (95% CI 4.6-15.8) and SjD was 6.6-fold (95% CI 3.56-12.26) more common in KS compared with the general male population (P < 0.001 by Fisher's exact test). SLE was 3.5-fold (95% CI 2.09-5.72) and SjD was 2.3-fold (95% CI 1.22-4.20) more common in triple X syndrome compared with the general female population (P < 0.001 and P < 0.05, respectively).

CONCLUSION

The extra X chromosome in KS and triple X syndrome appears to confer a nonproportional, synergistic dose effect on the development of SLE and SjD when compared with the general population.

X-inactive-specific transcript: a long noncoding RNA with a complex role in sex differences in human disease

In humans, the X and Y chromosomes determine the biological sex, XX specifying for females and XY for males. The long noncoding RNA X-inactive specific transcript (lncRNA XIST) plays a crucial role in the process of X chromosome inactivation (XCI) in cells of the female, a process that ensures the balanced expression of X-linked genes between sexes. Initially, it was believed that XIST can be expressed only from the inactive X chromosome (Xi) and is considered a typically female-specific transcript. However, accumulating evidence suggests that XIST can be detected in male cells as well, and it participates in the development of cancers and other human diseases by regulating gene expression at epigenetic, chromatin remodeling, transcriptional, and translational levels. XIST is abnormally expressed in many sexually dimorphic diseases, including autoimmune and neurological diseases, pulmonary arterial hypertension (PAH), and some types of cancers. However, the underlying mechanisms are not fully understood. Escape from XCI and skewed XCI also contributes to sex-biased diseases and their severity. Interestingly, in humans, similar to experimental animal models of human disease, the males with the XIST gene activated display the sex-biased disease condition at a rate close to females, and significantly greater than males who had not been genetically modified. For instance, the men with supernumerary X chromosomes, such as men with Klinefelter syndrome (47, XXY), are predisposed toward autoimmunity similar to females (46, XX), and have increased risk for strongly female biased diseases, compared to 46, XY males. Interestingly, chromosome X content has been linked to a longer life span, and the presence of two chromosome X contributes to increased longevity regardless of the hormonal status. In this review, we summarize recent knowledge about XIST structure/function correlation and involvement in human disease with focus on XIST abnormal expression in males. Many human diseases show differences between males and females in penetrance, presentation, progression, and survival. In humans, the X and Y sex chromosomes determine the biological sex, XX specifying for females and XY for males. This numeric imbalance, two X chromosomes in females and only one in males, known as sex chromosome dosage inequality, is corrected in the first days of embryonic development by inactivating one of the X chromosomes in females. While this "dosage compensation" should in theory solve the difference in the number of genes between sexes, the expressed doses of X genes are incompletely compensated by X chromosome inactivation in females. In this review we try to highlight how abnormal expression and function of XIST, a gene on the X chromosome responsible for this inactivation process, may explain the sex differences in human health and disease. A better understanding of the molecular mechanisms of XIST participation in the male-female differences in disease is highly relevant since it would allow for improving the personalization of diagnosis and sex-specific treatment of patients.

Sex-specific differences in SLE - Significance in the experimental setting of inflammation and kidney damage in MRL-Faslpr mice

Animal models are an important tool in the research of chronic autoimmune diseases, like systemic lupus erythematosus (SLE). MRL-Faslpr mice are one of different lupus models that develop spontaneously an SLE-like disease with autoantibodies and immune complex deposition that leads into damage of different organs. In contrast to human SLE, both sexes of MRL-Faslpr mice develop a similar autoimmune disease. Due to the sex bias in human and the delayed disease progression in male MRL-Faslpr mice, the majority of studies have been performed in female mice. To determine the suitability of male MRL-Faslpr mice for SLE research, especially with regard to the 3 R-principle and animal welfare, analyses of phenotype, inflammation and damage with focus on kidney and spleen were performed in mice of both sexes. Female mice developed lymphadenopathy and skin lesions earlier as males. At an age of 3.5 month, more immune cells infiltrated kidney and spleen in females compared to males. At the age of 5 months, however, substantially less sex-specific differences were detected. Since other studies have shown differences between both sexes on other manifestations like autoimmune pancreatitis and Sjögren syndrome in MRL-Faslpr mice, the use of male mice as part of 3 R-principle and animal welfare must be carefully considered.

Extrafollicular CD19lowCXCR5-CD11c- double negative 3 (DN3) B cells are significantly associated with disease activity in females with systemic lupus erythematosus

Objective

B cells play a major role in the development and maintenance of systemic lupus erythematosus (SLE). Double negative (DN) B cells defined by the lack of surface expression of IgD and CD27 have attracted recent interest for their sensitivity to Toll-like receptor 7 (TLR7) ligands and their potential role in the production of autoantibodies. Here we aimed at investigating the possible association of DN B cells and their subsets with SLE disease activity specifically in female patients, in which TLR7 gene has been reported to escape X chromosome inactivation.

Methods

Peripheral blood mononuclear cells were purified from woman participating to the clinically well-characterized Swiss SLE Cohort Study (SSCS). PBMC from age-matched healthy females were used as controls. PBMC were stained for cell surface markers, intracellular Tbet and analyzed by multicolor cytofluorimetry. Single nucleotide TLR7 polymorphisms were assessed by polymerase chain reaction.

Results

The median SLE disease activity index of the 86 females was 2, IQR [0-6], all but 8 were under chronic SLE treatment. B cells co-expressing CD11c and Tbet were increased, the mean fluorescence intensity (MFI) of CD19 was considerably reduced and we observed a large increase in CD11c + CXCR5-and CD11c-CXCR5-concomitantly with a reduction of CD11c-CXCR5+ B cells in SLE compared to 40 healthy donors (HD). When focusing on the DN B cell subset, we found a reduction of DN1 (CD11c-CXCR5+) and an increase of DN2 (CD11c + CXCR5-) and most impressively of DN3 (CD11c-CXCR5-) cells. The DN subset, particularly DN3, showed the lowest level of CD19 expression. Both DN1 and DN3 percentages as well as the CD19 MFI of DN cells were associated with SLE disease activity. The use of glucocorticoids, immunosuppressants, and antimalarials impacted differentially on the frequencies of DN B cell subsets. CD19 MFI in B cells and the percentage of DN3 were the strongest biomarkers of disease activity. The TLR7 snp3858384 G allele was associated with increased percentages of B cells and CD19+CD11c-CXCR5+ and decreased CD19+CD11c-CXCR5-.

Conclusions

DN3 B cells are strongly associated with SLE clinical activity pointing to their potential involvement in disease pathogenesis, and CD19 expression level performs accurately as disease activity biomarker.

Female-bias in systemic lupus erythematosus: How much is the X chromosome to blame?

Systemic lupus erythematosus (SLE or lupus) is an immune-mediated disease associated with substantial medical burden. Notably, lupus exhibits a striking female bias, with women having significantly higher susceptibility compared to men, up to 14-fold higher in some ethnicities. Supernumerary X chromosome syndromes, like Klinefelter (XXY) and Triple X syndrome (XXX), also present higher SLE prevalence, whereas Turner syndrome (XO) displays lower prevalence. Taken together, SLE prevalence in different X chromosome dosage sceneries denotes a relationship between the number of X chromosomes and the risk of developing lupus. The dosage of X-linked genes, many of which play roles in the immune system, is compensated between males and females through the inactivation of one of the two X chromosomes in female cells. X-chromosome inactivation (XCI) initiates early in development with a random selection of which X chromosome to inactivate, a choice that is then epigenetically maintained in the daughter cells. This process is regulated by the X-Inactive-Specific Transcript (XIST), encoding for a long non-coding RNA, exclusively expressed from the inactive X chromosome (Xi). XIST interacts with various RNA binding proteins and chromatin modifiers to form a ribonucleoprotein (RNP) complex responsible for the transcriptional silencing and heterochromatinization of the Xi. This ensures stable silencing of most genes on the X chromosome, with only a few genes able to escape this process. Recent findings suggest that the molecular components involved in XCI, or their dysregulation, contribute to the pathogenesis of lupus. Indeed, nonrandom XCI, elevated gene escape from XCI, and the autoimmune potential of the XIST RNP complex have been suggested to contribute to auto-immune diseases, such as lupus. This review examines these current hypotheses concerning how this dosage compensation mechanism might impact the development of lupus, shedding light on potential mechanisms underlying the pathogenesis of the disease.

Sex Dimorphism in Pulmonary Arterial Hypertension Associated With Autoimmune Diseases

Pulmonary hypertension is a rare, incurable, and progressive disease. Although there is increasing evidence that immune disorders, particularly those associated with connective tissue diseases, are a strong predisposing factor in the development of pulmonary arterial hypertension (PAH), there is currently a lack of knowledge about the detailed molecular mechanisms responsible for this phenomenon. Exploring this topic is crucial because patients with an immune disorder combined with PAH have a worse prognosis and higher mortality compared with patients with other PAH subtypes. Moreover, data recorded worldwide show that the prevalence of PAH in women is 2× to even 4× higher than in men, and the ratio of PAH associated with autoimmune diseases is even higher (9:1). Sexual dimorphism in the pathogenesis of cardiovascular disease was explained for many years by the action of female sex hormones. However, there are increasing reports of interactions between sex hormones and sex chromosomes, and differences in the pathogenesis of cardiovascular disease may be controlled not only by sex hormones but also by sex chromosome pathways that are not dependent on the gonads. This review discusses the role of estrogen and genetic factors including the role of genes located on the X chromosome, as well as the potential protective role of the Y chromosome in sexual dimorphism, which is prominent in the occurrence of PAH associated with autoimmune diseases. Moreover, an overview of animal models that could potentially play a role in further investigating the aforementioned link was also reviewed.

Sex as a biological variable in ageing: insights and perspectives on the molecular and cellular hallmarks

Sex-specific differences in lifespan and ageing are observed in various species. In humans, women generally live longer but are frailer and suffer from different age-related diseases compared to men. The hallmarks of ageing, such as genomic instability, telomere attrition or loss of proteostasis, exhibit sex-specific patterns. Sex chromosomes and sex hormones, as well as the epigenetic regulation of the inactive X chromosome, have been shown to affect lifespan and age-related diseases. Here we review the current knowledge on the biological basis of sex-biased ageing. While our review is focused on humans, we also discuss examples of model organisms such as the mouse, fruit fly or the killifish. Understanding these molecular differences is crucial as the elderly population is expected to double worldwide by 2050, making sex-specific approaches in the diagnosis, treatment, therapeutic development and prevention of age-related diseases a pressing need.

Unique Interplay Between Antinuclear Antibodies and Nuclear Molecules in the Pathogenesis of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease that primarily affects young women and causes a wide range of inflammatory manifestations. The hallmark of SLE is the production of antibodies to components of the cell nucleus (antinuclear antibodies [ANAs]). These antibodies can bind to DNA, RNA, and protein complexes with nucleic acids. Among ANAs, antibodies to DNA (anti-DNA) are markers for classification and disease activity, waxing and waning disease activity in many patients. In the blood, anti-DNA antibodies can bind to DNA to form immune complexes with two distinct roles in pathogenesis: (1) renal deposition to provoke nephritis and (2) stimulation of cytokine production following uptake into innate immune cells and interaction with internal nucleic acid sensors. These sensors are part of an internal host defense system in the cell cytoplasm that can respond to DNA from infecting organisms; during cell stress, DNA from nuclear and mitochondrial sources can also trigger these sensors. The formation of immune complexes requires a source of extracellular DNA in an immunologically accessible form. As shown in in vivo and in vitro systems, extracellular DNA can emerge from dead and dying cells in both a free and a particulate form. Neutrophils undergoing the process of NETosis can release DNA in mesh-like structures called neutrophil extracellular traps. In SLE, therefore, the combination of ANAs and immunologically active DNA can create new structures that can promote inflammation throughout the body as well as drive organ inflammation and damage.

Sex differences in CD8+ T cell responses during adaptive immunity

Biological sex is an important variable that influences the immune system's susceptibility to infectious and non-infectious diseases and their outcomes. Sex dimorphic features in innate and adaptive immune cells and their activities may help to explain sex differences in immune responses. T lymphocytes in the adaptive immune system are essential to providing protection against infectious and chronic inflammatory diseases. In this review, T cell responses are discussed with focus on the current knowledge of biological sex differences in CD8+ T cell mediated adaptive immune responses in infectious and chronic inflammatory diseases. Future directions aimed at investigating the molecular and cellular mechanisms underlying sex differences in diverse T cell responses will continue to underscore the significance of understanding sex differences in protective immunity at the cellular level, to induce appropriate T cell-based immune responses in infection, autoimmunity, and cancer. This article is categorized under: Immune System Diseases > Molecular and Cellular Physiology Infectious Diseases > Molecular and Cellular Physiology.

Pregnancy complications and autoimmune diseases in women: systematic review and meta-analysis

BACKGROUND

Pregnancy complications might lead to the development of autoimmune diseases in women. This review aims to summarise studies evaluating the association between pregnancy complications and the development of autoimmune diseases in women.

METHODS

Medline, CINAHL, and Cochrane databases were searched up to January 2024. Nineteen pregnancy complications and 15 autoimmune conditions were included. Title, abstract, full-text screening, data extraction, and quality assessment were performed by two reviewers independently. Data were synthesised using narrative and quantitative methods. Results were presented using odds ratios (OR), relative risks (RR), incidence rate ratios (IRR), and 95% confidence intervals (CI).

RESULTS

Thirty studies were included. One study reported composite exposure to pregnancy complications had a risk of any autoimmune disease RR 3.20 (2.90-3.51) compared to women without pregnancy complications. Women with hyperemesis gravidarum had a higher risk of developing coeliac disease (n = 1) IRR 1.98 (1.27-2.94), Crohn's disease (n = 1) IRR 1.61 (1.25-2.04), psoriasis (n = 1) IRR 1.33 (1.01-1.71), and rheumatoid arthritis (n = 2) IRR 1.35 (1.09-1.64). Miscarriage associated with subsequent diagnosis of Sjogren syndrome (n = 2) IRR 1.33 (1.06-2.81) and rheumatoid arthritis (n = 4) OR 1.11 (1.04-1.20). Gestational hypertension/preeclampsia was linked with the development of systemic sclerosis (n = 2) IRR 2.60 (1.10-4.60) and T1DM (n = 2) IRR 2.37 (2.09-2.68). Stillbirth associated with composite autoimmune conditions (n = 2) RR 5.82 (95% CI 4.87-6.81) and aIRR 1.25 (1.12-1.40). Postpartum psychosis was associated with autoimmune thyroid disease (n = 1) aIRR2.26 (1.61-2.90).

CONCLUSIONS

Women with pregnancy complications subsequently had a higher risk of being diagnosed with autoimmune conditions. Whether this is due to pre-existing undiagnosed health conditions or being causally linked to pregnancy complications is not known.

Epigenetic developmental mechanisms underlying sex differences in cancer

Cancer risk is modulated by hereditary and somatic mutations, exposures, age, sex, and gender. The mechanisms by which sex and gender work alone and in combination with other cancer risk factors remain underexplored. In general, cancers that occur in both the male and female sexes occur more commonly in XY compared with XX individuals, regardless of genetic ancestry, geographic location, and age. Moreover, XY individuals are less frequently cured of their cancers, highlighting the need for a greater understanding of sex and gender effects in oncology. This will be necessary for optimal laboratory and clinical cancer investigations. To that end, we review the epigenetics of sexual differentiation and its effect on cancer hallmark pathways throughout life. Specifically, we will touch on how sex differences in metabolism, immunity, pluripotency, and tumor suppressor functions are patterned through the epigenetic effects of imprinting, sex chromosome complement, X inactivation, genes escaping X inactivation, sex hormones, and life history.

Long Non-Coding RNAs in Sjögren's Disease

Sjögren's disease (SjD) is a heterogeneous autoimmune disease characterized by severe dryness of mucosal surfaces, particularly the mouth and eyes; fatigue; and chronic pain. Chronic inflammation of the salivary and lacrimal glands, auto-antibody formation, and extra-glandular manifestations occur in subsets of patients with SjD. An aberrant expression of long, non-coding RNAs (lncRNAs) has been described in many autoimmune diseases, including SjD. Here, we review the current literature on lncRNAs in SjD and their role in regulating X chromosome inactivation, immune modulatory functions, and their potential as biomarkers.

Neurological risks of COVID-19 in women: the complex immunology underpinning sex differences

The COVID-19 pandemic has uncovered many mysteries about SARS-CoV-2, including its potential to trigger abnormal autoimmune responses. Emerging evidence suggests women may face higher risks from COVID-induced autoimmunity manifesting as persistent neurological symptoms. Elucidating the mechanisms underlying this female susceptibility is now imperative. We synthesize key insights from existing studies on how COVID-19 infection can lead to immune tolerance loss, enabling autoreactive antibodies and lymphocyte production. These antibodies and lymphocytes infiltrate the central nervous system. Female sex hormones like estrogen and X-chromosome mediated effects likely contribute to dysregulated humoral immunity and cytokine profiles among women, increasing their predisposition. COVID-19 may also disrupt the delicate immunological balance of the female microbiome. These perturbations precipitate damage to neural damage through mechanisms like demyelination, neuroinflammation, and neurodegeneration - consistent with the observed neurological sequelae in women. An intentional focus on elucidating sex differences in COVID-19 pathogenesis is now needed to inform prognosis assessments and tailored interventions for female patients. From clinical monitoring to evaluating emerging immunomodulatory therapies, a nuanced women-centered approach considering the hormonal status and immunobiology will be vital to ensure equitable outcomes. Overall, deeper insights into the apparent female specificity of COVID-induced autoimmunity will accelerate the development of solutions mitigating associated neurological harm.

The impact of chromosomal sex on cardiometabolic health and disease

Many aspects of metabolism are sex-biased, from gene expression in metabolic tissues to the prevalence and presentation of cardiometabolic diseases. The influence of hormones produced by male and female gonads has been widely documented, but recent studies have begun to elucidate the impact of genetic sex (XX or XY chromosomes) on cellular and organismal metabolism. XX and XY cells have differential gene dosage conferred by specific genes that escape X chromosome inactivation or the presence of Y chromosome genes that are absent from XX cells. Studies in mouse models that dissociate chromosomal and gonadal sex have uncovered mechanisms for sex-biased epigenetic, transcriptional, and post-transcriptional regulation of gene expression in conditions such as obesity, atherosclerosis, pulmonary hypertension, autoimmune disease, and Alzheimer's disease.