Sex Differences in Primary HIV Infection: Revisiting the Role of TLR7-Driven Type 1 IFN Production by Plasmacytoid Dendritic Cells in Women

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.

The role of genetic diversity, epigenetic regulation, and sex-based differences in HIV cure research: a comprehensive review

Despite significant advances in HIV treatment, a definitive cure remains elusive. The first-in-human clinical trial of Excision BioTherapeutics' CRISPR-based HIV cure, EBT-101, demonstrated safety but failed to prevent viral rebound. These outcomes may result from the interplay of several factors. Growing evidence indicates that intricate epigenetic modifications play a major role in the persistence of HIV latency, presenting a significant barrier to eradication efforts and causing viral rebound after ART discontinuation. Current strategies to purge the latent reservoir involve LRAs that reactivate latent proviruses. However, their clinical success is hindered by the heterogeneity of HIV reservoirs and the virus's diverse pathways. Additionally, RNA modifications like N6-methyladenosine (m^6 A) methylation influence HIV biology beyond transcriptional control, affect RNA stability, splicing, and translation, which could enhance therapeutic efficacy. The regulatory framework of chromatin dynamics is also key to understanding viral latency and reactivation, such as Vpr's role in reactivating latent HIV by targeting HDACs. Sex-specific factors were also shown to play an important role with females, showing stronger early immune responses and higher representation among elite controllers. This review addresses the multifaceted challenges of HIV cure research, focusing on genetic diversity, epigenetic regulation, RNA modifications, chromatin remodeling, and sex-specific factors. By integrating insights into these aspects, this paper aims to advance our understanding of HIV cure strategies and highlight directions for future research.

HIV-1 reservoir landscape of post-treatment control

PURPOSE OF REVIEW

This review explores the viral reservoir landscape in individuals who control viral replication after treatment interruption (TI), designated as post-treatment controllers (PTCs). Identifying their virologic features is crucial to inform drug-free HIV remission strategies.

RECENT FINDINGS

Traditionally characterized as small, likely due to early treatment, the viral reservoir of PTCs, after TI, exhibits limited transcriptional activity, residual viral replication and subsequent proviral diversity. Intact proviruses are found to be restricted. In nonhuman primate PTCs, this depletion of intact proviruses is already observed in lymph nodes before TI, suggesting that control mechanisms begin during antiretroviral therapy. Furthermore, recent studies suggest immune-driven proviral deep latency associated with repressive epigenetic features and integration sites in PTCs. While molecular mapping of virological features of PTCs is increasingly precise and coupled with in-depth immunologic assays, robust predictive biomarkers of PTCs are still lacking.

SUMMARY

Despite limited sample sizes and heterogeneous definitions, common virologic features of PTCs include restricted reservoir size and transcriptional activity, fewer intact proviruses and deep proviral latency. Ongoing research using innovative technologies will further elucidate the mechanisms underlying post-treatment control, paving the way for successful HIV cure interventions.

Type I Interferonopathy among Non-Elderly Female Patients with Post-Acute Sequelae of COVID-19

The pathophysiological mechanisms of the post-acute sequelae of COVID-19 (PASC) remain unclear. Sex differences not only exist in the disease severity of acute SARS-CoV-2 infection but also in the risk of suffering from PASC. Women have a higher risk of suffering from PASC and a longer time to resolution than men. To explore the possible immune mechanisms of PASC among non-elderly females, we mined single-cell transcriptome data from peripheral blood samples of non-elderly female patients with PASC and acute SARS-CoV-2 infection, together with age- and gender-matched non-PASC and healthy controls available from the Gene Expression Omnibus database. By comparing the differences, we found that a CD14+ monocyte subset characterized by higher expression of signal transducers and activators of transcription 2 (STAT2) (CD14+STAT2high) was notably increased in the PASC patients compared with the non-PASC individuals. The transcriptional factor (TF) activity analysis revealed that STAT2 and IRF9 were the key TFs determining the function of CD14+STAT2high monocytes. STAT2 and IRF9 are TFs exclusively involving type I and III interferon (IFN) signaling pathways, resulting in uncontrolled IFN-I signaling activation and type I interferonopathy. Furthermore, increased expression of common interferon-stimulated genes (ISGs) has also been identified in most monocyte subsets among the non-elderly female PASC patients, including IFI6, IFITM3, IFI44L, IFI44, EPSTI1, ISG15, and MX1. This study reveals a featured CD14+STAT2high monocyte associated with uncontrolled IFN-I signaling activation, which is indicative of a possible type I interferonopathy in the non-elderly female patients with PASC.

Toll-like Receptor Response to Human Immunodeficiency Virus Type 1 or Co-Infection with Hepatitis B or C Virus: An Overview

Toll-like receptors (TLRs) are evolutionarily conserved pattern recognition receptors that play important roles in the early detection of pathogen-associated molecular patterns and shaping innate and adaptive immune responses, which may influence the consequences of infection. Similarly to other viral infections, human immunodeficiency virus type 1 (HIV-1) also modulates the host TLR response; therefore, a proper understanding of the response induced by human HIV-1 or co-infection with hepatitis B virus (HBV) or hepatitis C virus (HCV), due to the common mode of transmission of these viruses, is essential for understanding HIV-1 pathogenesis during mono- or co-infection with HBV or HCV, as well as for HIV-1 cure strategies. In this review, we discuss the host TLR response during HIV-1 infection and the innate immune evasion mechanisms adopted by HIV-1 for infection establishment. We also examine changes in the host TLR response during HIV-1 co-infection with HBV or HCV; however, this type of study is extremely scarce. Moreover, we discuss studies investigating TLR agonists as latency-reverting agents and immune stimulators towards new strategies for curing HIV. This understanding will help develop a new strategy for curing HIV-1 mono-infection or co-infection with HBV or HCV.

Gender-Specific Impact of Sex Hormones on the Immune System

Sex hormones are key determinants of gender-related differences and regulate growth and development during puberty. They also exert a broad range modulation of immune cell functions, and a dichotomy exists in the immune response between the sexes. Both clinical and animal models have demonstrated that androgens, estrogens, and progestogens mediate many of the gender-specific differences in immune responses, from the susceptibility to infectious diseases to the prevalence of autoimmune disorders. Androgens and progestogens mainly promote immunosuppressive or immunomodulatory effects, whereas estrogens enhance humoral immunity both in men and in women. This study summarizes the available evidence regarding the physiological effects of sex hormones on human immune cell function and the underlying biological mechanisms, focusing on gender differences triggered by different amounts of androgens between males and females.

The Role of TRL7/8 Agonists in Cancer Therapy, with Special Emphasis on Hematologic Malignancies

Toll-like receptors (TLR) belong to the pattern recognition receptors (PRR). TLR7 and the closely correlated TLR8 affiliate with toll-like receptors family, are located in endosomes. They recognize single-stranded ribonucleic acid (RNA) molecules and synthetic deoxyribonucleic acid (DNA)/RNA analogs-oligoribonucleotides. TLRs are primarily expressed in hematopoietic cells. There is compiling evidence implying that TLRs also direct the formation of blood cellular components and make a contribution to the pathogenesis of certain hematopoietic malignancies. The latest research shows a positive effect of therapy with TRL agonists on the course of hemato-oncological diseases. Ligands impact activation of antigen-presenting cells which results in production of cytokines, transfer of mentioned cells to the lymphoid tissue and co-stimulatory surface molecules expression required for T-cell activation. Toll-like receptor agonists have already been used in oncology especially in the treatment of dermatological neoplastic lesions. The usage of these substances in the treatment of solid tumors is being investigated. The present review discusses the direct and indirect influence that TLR7/8 agonists, such as imiquimod, imidazoquinolines and resiquimod have on neoplastic cells and their promising role as adjuvants in anticancer vaccines.

Progressive multifocal leukoencephalopathy: epidemiology and spectrum of predisposing conditions

Population-based data on the epidemiology of progressive multifocal leukoencephalopathy, its predisposing conditions and mortality rate are lacking, although such data are crucial to raise awareness among clinicians and to lay foundations for future therapeutic trials in immunomodulating therapies. In our study, patients were identified by interrogating the French national healthcare reimbursement database from 1 January 2008 to 31 December 2017, using progressive multifocal leukoencephalopathy International Classification of Diseases code and a patient's selection algorithm. Overall incidence rate, 1-year all-cause mortality rate and survival patterns were calculated, and factors associated with death were identified using a multivariate Cox proportional hazards regression model. Our cohort is the largest to date, comprising 584 patients with incident progressive multifocal leukoencephalopathy. The overall incidence in France from 2010 to 2017 was stable during the study period at 0.11 per 100 000 person-years, 95% confidence interval [0.10-0.12]. Predisposing diseases were HIV infection (43.7%), followed by haematological malignancies (21.9%), chronic inflammatory diseases (20.2%), solid organ transplantation (4.3%), solid neoplasm (4.1%) and primary immune deficiency (1.5%). The 1-year mortality rate was 38.2%, with a 95% confidence interval (34.2-42.2). In multivariate analysis, factors independently associated with death were older age [adjusted hazard ratio 0.33 (0.20-0.53) for patients aged 20 to 40 compared with patients aged over 60], male gender [adjusted hazard ratio 0.73 (0.54-0.99) for females compared with males] and predisposing immunosuppressive disease, with the highest risk for solid neoplasms [adjusted hazard ratio 4.34 (2.25-8.37)], followed by haematological malignancies [adjusted hazard ratio 3.13 (1.85-5.30)] and HIV infection [adjusted hazard ratio 1.83 (1.12-3.00)], compared with chronic inflammatory diseases. Immune reconstitution inflammatory syndrome was notified in 7.0% of patients. In conclusion, incidence of progressive multifocal leukoencephalopathy is stable in France, and HIV infection remains the main predisposing disease. This large-size cohort uncovers a higher risk of mortality for male patients compared to females, and the worst prognosis for patients with solid neoplasm, while prognosis in patients with haematological malignancies appeared less dismal than in previous studies.

Potential immunological effects of gender-affirming hormone therapy in transgender people - an unexplored area of research

There are well-described sex-based differences in how the immune system operates. In particular, cisgender (cis) females have a more easily activated immune system; associated with an increased prevalence of autoimmune diseases and adverse events following vaccinations. Conversely, cis males have a higher threshold for immune activation, and are more prone to certain infectious diseases, such as coronavirus disease (COVID-19). Oestrogen and testosterone have immune-modulatory properties, and it is likely that these contribute to the sexual dimorphism of the immune system. There are also important immune-related genes located on the X chromosome, such as toll-like receptor (TLR) 7/8; and the mosaic bi-allelic expression of such genes may contribute to the state of immune hyperactivation in cis females. The scientific literature strongly suggests that sex-based differences in the functioning of the immune system are related to both X-linked genes and immune modulation by sex hormones. However, it is currently not clear how this impacts transgender (trans) people receiving gender-affirming hormonal therapy. Moreover, it is estimated that in Australia, at least 2.3% of adolescents identify as trans and/or gender diverse, and referrals to specialist gender-affirming care are increasing each year. Despite the improving social awareness of trans people, they remain chronically underrepresented in the scientific literature. In addition, a small number of case studies describe new onset autoimmune disorders in adult trans females following oestrogen use. However, there is currently minimal long-term research with an immunological focus on trans people. Therefore, to ensure the positive health outcomes of trans people, it is crucial that the role of sex hormones in immune modulation is investigated further.

Women for science and science for women: Gaps, challenges and opportunities towards optimizing pre-exposure prophylaxis for HIV-1 prevention

Preventing new HIV infections remains a global challenge. Young women continue to bear a disproportionate burden of infection. Oral pre-exposure prophylaxis (PrEP), offers a novel women-initiated prevention technology and PrEP trials completed to date underscore the importance of their inclusion early in trials evaluating new HIV PrEP technologies. Data from completed topical and systemic PrEP trials highlight the role of gender specific physiological and social factors that impact PrEP uptake, adherence and efficacy. Here we review the past and current developments of HIV-1 prevention options for women with special focus on PrEP considering the diverse factors that can impact PrEP efficacy. Furthermore, we highlight the importance of inclusion of female scientists, clinicians, and community advocates in scientific efforts to further improve HIV prevention strategies.

HIV-1 infection enhances innate function and TLR7 expression in female plasmacytoid dendritic cells

This study shows that the TLR7-driven innate function of pDCs is increased in HIV/ART women and is associated with enhanced expression of the TLR7 locus from both X chromosomes.

Plasmacytoid dendritic cells (pDCs) express TLR7, a ssRNA-sensor encoded on the X chromosome, which escapes X chromosome inactivation (XCI) in females. pDCs are specialized in the production of type 1 interferons (IFN-I) through TLR7 activation which mediates both immune cell activation and also reactivation of latent HIV-1. The effect of HIV-1 infection in women under antiretroviral therapy (ART) on pDC functional responses remains poorly understood. Here, we show that pDCs from HIV/ART women exhibit exacerbated production of IFN-α and TNF-α compared with uninfected controls (UC) upon TLR7 activation. Because TLR7 can escape XCI in female pDCs, we measured the contribution of TLR7 allelic expression using SNP haplotypic markers to rigorously tag the allele of origin of TLR7 gene at single-cell resolution. Herein, we provide evidence that the enhanced functional response of pDCs in HIV/ART women is associated with higher transcriptional activity of the TLR7 locus from both X chromosomes, rather than differences in the frequency of TLR7 biallelic cells. These data reinforce the interest in targeting the HIV-1 reservoir using TLR7 agonists in women.

The immune response to COVID-19: Does sex matter?

The coronavirus disease 2019 (COVID-19) pandemic has created unprecedented challenges worldwide. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19 and has a complex interaction with the immune system, including growing evidence of sex-specific differences in the immune response. Sex-disaggregated analyses of epidemiological data indicate that males experience more severe symptoms and suffer higher mortality from COVID-19 than females. Many behavioural risk factors and biological factors may contribute to the different immune response. This review examines the immune response to SARS-CoV-2 infection in the context of sex, with emphasis on potential biological mechanisms explaining differences in clinical outcomes. Understanding sex differences in the pathophysiology of SARS-CoV-2 infection will help promote the development of specific strategies to manage the disease.

Plasmacytoid dendritic cells during COVID-19: Ally or adversary?

Plasmacytoid dendritic cells (pDCs) are specialized cells of the immune system that are thought to be the main cellular source of type I interferon alpha (IFNα) in response to viral infections. IFNs are powerful antivirals, whereas defects in their function or induction lead to impaired resistance to virus infections, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19. IFN production needs to be controlled, because sustained IFN production can also have detrimental effects on disease outcome. As such, pDCs are likely important for acute antiviral protection against SARS-CoV-2 infection but could potentially also contribute to chronic IFN levels. Here, we provide a historical overview of pDC biology and summarize existing literature addressing their involvement and importance during viral infections of the airways. Furthermore, we outline recent reports focused on the potential role of pDCs during SARS-CoV-2 infection, as well as the potential for this cellular subset to impact COVID-19 disease outcome.

Contribution of Sex Differences to HIV Immunology, Pathogenesis, and Cure Approaches

Approximately 38 million people were living with human immunodeficiency virus (HIV) in 2020 and 53% of those infected were female. A variety of virological and immunological sex-associated differences (sexual dimorphism) in HIV infection have been recognized in males versus females. Social, behavioral, and societal influences play an important role in how the HIV pandemic has affected men and women differently. However, biological factors including anatomical, physiologic, hormonal, and genetic differences in sex chromosomes can each contribute to the distinct characteristics of HIV infection observed in males versus females. One striking example of this is the tendency for women to have lower HIV plasma viral loads than their male counterparts early in infection, though both progress to AIDS at similar rates. Sex differences in acquisition of HIV, innate and adaptive anti-HIV immune responses, efficacy/suitability of specific antiretroviral drugs, and viral pathogenesis have all been identified. Sex differences also have the potential to affect viral persistence, latency, and cure approaches. In this brief review, we summarize the major biological male/female sex differences in HIV infection and their importance to viral acquisition, pathogenesis, treatment, and cure efforts.