Antiviral immune responses in the genital tract: clues for vaccines

Herpes simplex virus spreads rapidly in human foreskin, partly driven by chemokine-induced redistribution of Nectin-1 on keratinocytes

HSV infects keratinocytes in the epidermis of skin via nectin-1. We established a human foreskin explant infection model to investigate HSV entry and spread. HSV1 entry could only be achieved by the topical application of virus via high density microarray projections (HD-MAPs) to the epidermis, which penetrated beyond one third of its thickness, simulating in vivo microtrauma. Rapid lateral spread of HSV1 to a mean of 13 keratinocytes wide occurred after 24 hours and free virus particles were observed between keratinocytes, consistent with an intercellular route of spread. Nectin-1 staining was markedly decreased in foci of infection in the epidermis and in the human keratinocyte HaCaT cell line. Nectin-1 was redistributed, at the protein level, in adjacent uninfected cells surrounding infection, inducible by CCL3, IL-8 (or CXCL8), and possibly CXCL10 and IL-6, thus facilitating spread. These findings provide the first insights into HSV1 entry and spread in human inner foreskin in situ.

Microbicides for Topical HIV Immunoprophylaxis: Current Status and Future Prospects

Microbicides, which are classified as topical antiseptic agents, are a revolutionary advancement in HIV prevention aimed to prevent the entry of infectious agents into the human body, thus stopping the sexual transmission of HIV and other sexually transmitted diseases. Microbicides represent the promise of a new age in preventive measures against one of the world's most pressing health challenges. In addition to their direct antiviral effects during HIV transmission, microbicides also influence vaginal mucosal immunity. This article reviews microbicides by presenting different drug classifications and highlighting significant representatives from each group. It also explains their mechanisms of action and presents information about vaginal mucosal immune responses, emphasizing the critical role they play in responding to HIV during sexual transmission. The article discusses the following groups of microbicides: surfactants or membrane disruptors, vaginal milieu protectors, anionic polymers, dendrimers, carbohydrate-binding proteins, HIV replication inhibitors (reverse transcriptase inhibitors), and multi-purpose prevention technologies, which combine protection against HIV, other sexually transmitted diseases, and contraception. For each chemical compound, the article provides a brief overview of relevant preclinical and clinical research, emphasizing their potential as microbicides. The article offers insights into the multifaceted impact of microbicides, which signify a pivotal step forward in the pursuit of effective and accessible pre-exposure prophylaxis (PrEP).

Advances and challenges in studying the tissue-resident T cell compartment in the human female reproductive tract

Tissue-resident memory T cells (TRM ) are considered to be central to maintaining mucosal barrier immunity and tissue homeostasis. Most of this knowledge stems from murine studies, which provide access to all organs. These studies also allow for a thorough assessment of the TRM compartment for each tissue and across tissues with well-defined experimental and environmental variables. Assessing the functional characteristics of the human TRM compartment is substantially more difficult; thus, notably, there is a paucity of studies profiling the TRM compartment in the human female reproductive tract (FRT). The FRT is a mucosal barrier tissue that is naturally exposed to a wide range of commensal and pathogenic microbes, including several sexually transmitted infections of global health significance. We provide an overview of studies describing T cells within the lower FRT tissues and highlight the challenges of studying TRM cells in the FRT: different sampling methods of the FRT greatly affect immune cell recovery, especially of TRM cells. Furthermore, menstrual cycle, menopause, and pregnancy affect FRT immunity, but little is known about changes in the TRM compartment. Finally, we discuss the potential functional plasticity of the TRM compartment during inflammatory episodes in the human FRT to maintain protection and tissue homeostasis, which are required to ensure reproductive fitness.

Chlamydia trachomatis-An Emerging Old Entity?

Chlamydia trachomatis is an evasive pathogen that can prompt severe clinical manifestations in humans such as vaginitis, epididymitis, lymphogranuloma venereum, trachoma, conjunctivitis and pneumonia. If left untreated, chronic infections with C. trachomatis can give rise to long-lasting and even permanent sequelae. To shed some light on its widespread nature, data from original research, systematic reviews and meta-analyses from three databases was collected and analyzed in the context of chlamydial infection, related symptoms and appropriate treatment modalities. This review describes the bacterium's pervasiveness on a global scale, especially in developing countries, and suggests ways to halt its transmission and spread. Infections with C. trachomatis often go unnoticed, as many individuals are asymptomatic and unaware of their diagnosis, contributing to a delay in diagnosis and treatment. The high prevalence of chlamydial infection highlights the need for a universal screening and detection method enabling immediate treatment at its onset. Prognosis is favorable with antibiotic therapy and education for high-risk groups and their sexual partners. In the future, a quick, easily accessible, and inexpensive test should be developed to diagnose and treat infected individuals early on. Along with a vaccine against C. trachomatis, it would halt the transmission and spread of the pathogen worldwide.

Female reproductive tract-organ axes

The female reproductive tract (FRT) and remote/versatile organs in the body share bidirectional communication. In this review, we discuss the framework of the "FRT-organ axes." Each axis, namely, the vagina-gut axis, uterus-gut axis, ovary-gut axis, vagina-bladder axis, vagina-oral axis, uterus-oral axis, vagina-brain axis, uterus-brain axis, and vagina-joint axis, is comprehensively discussed separately. Each axis could be involved in the pathogenesis of not only gynecological diseases but also diseases occurring apart from the FRT. Although the microbiota is clearly a key player in the FRT-organ axes, more quantitative insight into the homeostasis of the microbiota could be provided by host function measurements rather than current microbe-centric approaches. Therefore, investigation of the FRT-organ axes would provide us with a multicentric approach, including immune, neural, endocrine, and metabolic aspects, for understanding the homeostatic mechanism of women's bodies. The framework of the FRT-organ axes could also provide insights into finding new therapeutic approaches to maintain women's health.

Differential expression of nuclear hormone receptors by dendritic cell subsets in human vaginal mucosa and skin

Nuclear hormone receptors (NHRs) expressed by dendritic cells (DCs), the major immune inducers and regulators, could play important roles in host immunity. Assessment of NHRs expressed by DCs in the vaginal mucosa (VM), in comparison with those expressed by DCs in other tissues, will thus help us understand the immunology of human vagina. This study identified 16 NHR transcripts that are differentially expressed among 8 different antigen-presenting cell (APC) subsets isolated from human VM, skin, and blood. The expression profiles of NHRs were largely tissue specific. VM APCs expressed increased levels of LXRA, RXRA, ESRRA, ESRRAP2, and PPARG, whereas skin and blood APCs expressed increased levels of NURR1, NOR1 and RARA. Of interest, female sex hormone receptors, ESR1 and PGR, were found to be mainly expressed by non-APC cell types in the VM; ESR1 by HLA-DR⁺CD34⁺ and PGR by HLA-DR^- cells. ERα and PR were expressed by vimentin⁺ cells in the VM, but not in human skin. ERα, but not PR, was also expressed in CD10⁺ cells in the lamina propria of VM. In conclusion, NHR expression by APC subsets is tissue- and cell type-specific. Future studies on the roles of individual NHRs expressed by different cell types, including DC subsets, in the human VM are warranted.

Defensins: defenders of human reproductive health

BACKGROUND

Reproductive tract infection is an important factor leading to male and female infertility. Among female infertility factors, microbial and viral infections are the main factors affecting female reproductive health and causing tubal infertility, ectopic tubal pregnancy and premature delivery. Among male infertility factors, 13-15% of male infertility is related to infection. Defensins are cationic antibacterial and antiviral peptides, classified into α-defensins, β-defensins and θ-defensins. Humans only have α-defensins and β-defensins. Apart from their direct antimicrobial functions, defensins have an immunomodulatory function and are involved in many physiological processes. Studies have shown that defensins are widely distributed in the female reproductive tract (FRT) and male reproductive tract (MRT), playing a dual role of host defence and fertility protection. However, to our knowledge, the distribution, regulation and function of defensins in the reproductive tract and their relation to reproduction have not been reviewed.

OBJECTIVE AND RATIONALE

This review summarizes the expression, distribution and regulation of defensins in the reproductive tracts to reveal the updated research on the dual role of defensins in host defence and the protection of fertility.

SEARCH METHODS

A systematic search was conducted in PubMed using the related keywords through April 2022. Related data from original researches and reviews were integrated to comprehensively review the current findings and understanding of defensins in the human reproductive system. Meanwhile, female and male transcriptome data in the GEO database were screened to analyze defensins in the human reproductive tracts.

OUTCOMES

Two transcriptome databases from the GEO database (GSE7307 and GSE150852) combined with existing researches reveal the expression levels and role of the defensins in the reproductive tracts. In the FRT, a high expression level of α-defensin is found, and the expression levels of defensins in the vulva and vagina are higher than those in other organs. The expression of defensins in the endometrium varies with menstrual cycle stages and with microbial invasion. Defensins also participate in the local immune response to regulate the risk of spontaneous preterm birth. In the MRT, a high expression level of β-defensins is also found. It is mainly highly expressed in the epididymal caput and corpus, indicating that defensins play an important role in sperm maturation. The expression of defensins in the MRT varies with androgen levels, age and the status of microbial invasion. They protect the male reproductive system from bacterial infections by neutralizing lipopolysaccharide and downregulating pro-inflammatory cytokines. In addition, animal and clinical studies have shown that defensins play an important role in sperm maturation, motility and fertilization.

WIDER IMPLICATIONS

As a broad-spectrum antimicrobial peptide without drug resistance, defensin has great potential for developing new natural antimicrobial treatments for reproductive tract infections. However, increasing evidence has shown that defensins can not only inhibit microbial invasion but can also promote the invasion and adhesion of some microorganisms in certain biological environments, such as human immunodeficiency virus. Therefore, the safety of defensins as reproductive tract anti-infective drugs needs more in-depth research. In addition, the modulatory role of defensins in fertility requires more in-depth research since the current conclusions are based on small-size samples. At present, scientists have made many attempts at the clinical transformation of defensins. However, defensins have problems such as poor stability, low bioavailability and difficulties in their synthesis. Therefore, the production of safe, effective and low-cost drugs remains a challenge.

Interferon Epsilon Signaling Confers Attenuated Zika Replication in Human Vaginal Epithelial Cells

Zika virus (ZIKV) is an emerging flavivirus that causes congenital birth defects and neurological compilations in the human host. Although ZIKV is primarily transmitted through infected mosquitos, recent studies reveal sexual contact as a potential transmission route. In vagina-bearing individuals, the vaginal epithelium constitutes the first line of defense against viruses. However, it is unclear how ZIKV interacts with the vaginal epithelium to initiate ZIKV transmission. In this study, we demonstrate that exposing ZIKV to human vaginal epithelial cells (hVECs) resulted in de novo viral RNA replication, increased envelope viral protein production, and a steady, extracellular release of infectious viral particles. Interestingly, our data show that, despite an increase in viral load, the hVECs did not exhibit significant cytopathology in culture as other cell types typically do. Furthermore, our data reveal that the innate antiviral state of hVECs plays a crucial role in preventing viral cytopathology. For the first time, our data show that interferon epsilon inhibits ZIKV replication. Collectively, our results in this study provide a novel perspective on the viral susceptibility and replication dynamics during ZIKV infection in the human vaginal epithelium. These findings will be instrumental towards developing therapeutic agents aimed at eliminating the pathology caused by the virus.

Towards the future exploration of mucosal mRNA vaccines against emerging viral diseases; lessons from existing next-generation mucosal vaccine strategies

The mRNA vaccine platform has offered the greatest potential in fighting the COVID-19 pandemic owing to rapid development, effectiveness, and scalability to meet the global demand. There are many other mRNA vaccines currently being developed against different emerging viral diseases. As with the current COVID-19 vaccines, these mRNA-based vaccine candidates are being developed for parenteral administration via injections. However, most of the emerging viruses colonize the mucosal surfaces prior to systemic infection making it very crucial to target mucosal immunity. Although parenterally administered vaccines would induce a robust systemic immunity, they often provoke a weak mucosal immunity which may not be effective in preventing mucosal infection. In contrast, mucosal administration potentially offers the dual benefit of inducing potent mucosal and systemic immunity which would be more effective in offering protection against mucosal viral infection. There are however many challenges posed by the mucosal environment which impede successful mucosal vaccination. The development of an effective delivery system remains a major challenge to the successful exploitation of mucosal mRNA vaccination. Nonetheless, a number of delivery vehicles have been experimentally harnessed with different degrees of success in the mucosal delivery of mRNA vaccines. In this review, we provide a comprehensive overview of mRNA vaccines and summarise their application in the fight against emerging viral diseases with particular emphasis on COVID-19 mRNA platforms. Furthermore, we discuss the prospects and challenges of mucosal administration of mRNA-based vaccines, and we explore the existing experimental studies on mucosal mRNA vaccine delivery.

Tissue-resident memory T cells in the urogenital tract

Our understanding of T cell memory responses changed drastically with the discovery that specialized T cell memory populations reside within peripheral tissues at key pathogen entry sites. These tissue-resident memory T (T_RM) cells can respond promptly to an infection without the need for migration, proliferation or differentiation. This rapid and local deployment of effector functions maximizes the ability of T_RM cells to eliminate pathogens. T_RM cells do not circulate through peripheral tissues but instead form isolated populations in the skin, gut, liver, kidneys, the reproductive tract and other organs. This long-term retention in the periphery might allow T_RM cells to fully adapt to the local conditions of their environment and mount customized responses to counter infection and tumour growth in a tissue-specific manner. In the urogenital tract, T_RM cells must adapt to a unique microenvironment to confer protection against potential threats, including cancer and infection, while preventing the onset of auto-inflammatory disease. In this Review, we discuss insights into the diversification of T_RM cells from other memory T cell lineages, the adaptations of T_RM cells to their local environment, and their enhanced capacity to counter infection and tumour growth compared with other memory T cell populations, especially in the urogenital tract.

From Bench to the Clinic: The Path to Translation of Nanotechnology-Enabled mRNA SARS-CoV-2 Vaccines

During the last decades, the use of nanotechnology in medicine has effectively been translated to the design of drug delivery systems, nanostructured tissues, diagnostic platforms, and novel nanomaterials against several human diseases and infectious pathogens. Nanotechnology-enabled vaccines have been positioned as solutions to mitigate the pandemic outbreak caused by the novel pathogen severe acute respiratory syndrome coronavirus 2. To fast-track the development of vaccines, unprecedented industrial and academic collaborations emerged around the world, resulting in the clinical translation of effective vaccines in less than one year. In this article, we provide an overview of the path to translation from the bench to the clinic of nanotechnology-enabled messenger ribonucleic acid vaccines and examine in detail the types of delivery systems used, their mechanisms of action, obtained results during each phase of their clinical development and their regulatory approval process. We also analyze how nanotechnology is impacting global health and economy during the COVID-19 pandemic and beyond.

Tissue-resident immunity in the female and male reproductive tract

The conception of how the immune system is organized has been significantly challenged over the last years. It became evident that not all lymphocytes are mobile and recirculate through secondary lymphoid organs. Instead, subsets of immune cells continuously reside in tissues until being reactivated, e.g., by a recurring pathogen or other stimuli. Consequently, the concept of tissue-resident immunity has emerged, and substantial evidence is now available to support its pivotal function in maintaining tissue homeostasis, sensing challenges and providing antimicrobial protection. Surprisingly, insights on tissue-resident immunity in the barrier tissues of the female reproductive tract are sparse and only slowly emerging. The need for protection from vaginal and amniotic infections, the uniqueness of periodic tissue shedding and renewal of the endometrial barrier tissue, and the demand for a tailored decidual immune adaptation during pregnancy highlight that tissue-resident immunity may play a crucial role in distinct compartments of the female reproductive tract. This review accentuates the characteristics of tissue-resident immune cells in the vagina, endometrium, and the decidua during pregnancy and discusses their functional role in modulating the risk for infertility, pregnancy complications, infections, or cancer. We here also review data published to date on tissue-resident immunity in the male reproductive organs, which is still a largely uncharted territory.

Cell type-specific expression of estrogen and progesterone receptors in the human vaginal mucosa

Female sex hormones affect the immune response in the lower female genital tract. To understand their mechanisms of action, it is essential to define cell types expressing estrogen receptor (ER) and/or progesterone receptor (PR) in the human vaginal mucosa (VM). Here, we report that none of the dendritic cell (DC) subsets in the human VM expressed ERα or PR in situ. However, they were capable of expressing ERα, but not PR, after in vitro culture of the whole VM tissues. Similarly, ERα and/or PR expression by T cells in the VM tissues was also inducible rather than constitutive. In contrast, ERα and/or PR were constitutively expressed in HLA-DR^- non-immune cell types (vimentin⁺, desmin⁺, or CD10⁺). These new findings will help us understand the mechanisms of action of female sex hormones in the modulation of immune response in the human VM and lower female genital tract.

Vaginal delivery of vaccines

Recent estimates suggest that one in two sexually active individuals will acquire a sexually transmitted infection by age 25, an alarming statistic that amounts to over 1 million new infections per day worldwide. Vaccination against STIs is highly desirable for alleviating this global burden of disease. Vaginal immunization is a promising strategy to combat transmission via the vaginal mucosa. The vagina is typically considered a poor inductive site for common correlates of adaptive immunity. However, emerging evidence suggests that immune tolerance may be overcome by precisely engineered vaccination schemes that orchestrate cell-mediated immunity and establish tissue resident memory immune cells. In this review, we will discuss the unique immunological milieu of the vaginal mucosa and our current understanding of correlates of pathogenesis and protection for several common STIs. We then present a summary of recent vaginal vaccine studies and explore the role that mucosal adjuvants and delivery systems play in enhancing protection according to requisite features of immunity. Finally, we offer perspectives on the challenges and future directions of vaginal vaccine delivery, discussing remaining physiological barriers and innovative vaccine formulations that may overcome them.

Preventive HIV Vaccines-Leveraging on Lessons from the Past to Pave the Way Forward

Almost four decades on, since the 1980’s, with hundreds of HIV vaccine candidates tested in both non-human primates and humans, and several HIV vaccines trials later, an efficacious HIV vaccine continues to evade us. The enormous worldwide genetic diversity of HIV, combined with HIV’s inherent recombination and high mutation rates, has hampered the development of an effective vaccine. Despite the advent of antiretrovirals as pre-exposure prophylaxis and preventative treatment, which have shown to be effective, HIV infections continue to proliferate, highlighting the great need for a vaccine. Here, we provide a brief history for the HIV vaccine field, with the most recent disappointments and advancements. We also provide an update on current passive immunity trials, testing proof of the concept of the most clinically advanced broadly neutralizing monoclonal antibodies for HIV prevention. Finally, we include mucosal immunity, the importance of vaccine-elicited immune responses and the challenges thereof in the most vulnerable environment–the female genital tract and the rectal surfaces of the gastrointestinal tract for heterosexual and men who have sex with men transmissions, respectively.

The human memory T cell compartment changes across tissues of the female reproductive tract

Memory CD4 T cells in tissues fulfill numerous functions that are critical for local immune homeostasis and protection against pathogens. Previous studies have highlighted the phenotypic and functional heterogeneity of circulating and tissue-resident memory CD4 T cells across different human tissues such as skin, lung, liver, and colon. Comparatively little is known in regard to memory CD4 T cells across tissues of the female reproductive tract (FRT). We examined CD4 T cells in donor-matched vaginal, ecto- and endocervical tissues, which differ in mucosal structure and exposure to external environmental stimuli. We hypothesized that this could be reflected by tissue-specific differences in the memory CD4 T cell compartment. We found differences in CD4 subset distribution across these tissues. Specifically, CD69⁺CD103⁺ CD4 T cells were significantly more abundant in vaginal than cervical tissues. In contrast, the transcriptional profiles of CD4 subsets were fairly conserved across FRT tissues. CD69⁺CD103⁺ CD4 T cells showed a T_H17 bias independent of tissue niche. Our data suggest that FRT tissues affect T cell subset distribution but have limited effects on the transcriptome of each subset. We discuss the implications for barrier immunity in the FRT.

Cervicovaginal Tissue Residence Confers a Distinct Differentiation Program upon Memory CD8 T Cells

Tissue-resident memory CD8 T cells (CD8 T_RM) are critical for maintaining barrier immunity. CD8 T_RM have been mainly studied in the skin, lung and gut, with recent studies suggesting that the signals that control tissue residence and phenotype are highly tissue dependent. We examined the T cell compartment in healthy human cervicovaginal tissue (CVT) and found that most CD8 T cells were granzyme B⁺ and TCF-1^- To address if this phenotype is driven by CVT tissue residence, we used a mouse model to control for environmental factors. Using localized and systemic infection models, we found that CD8 T_RM in the mouse CVT gradually acquired a granzyme B⁺, TCF-1^- phenotype as seen in human CVT. In contrast to CD8 T_RM in the gut, these CD8 T_RM were not stably maintained regardless of the initial infection route, which led to reductions in local immunity. Our data show that residence in the CVT is sufficient to progressively shape the size and function of its CD8 T_RM compartment.

HPV and Other Microbiota; Who's Good and Who's Bad: Effects of the Microbial Environment on the Development of Cervical Cancer-A Non-Systematic Review

Cervical cancer is responsible for around 5% of all human cancers worldwide. It develops almost exclusively from an unsolved, persistent infection of the squamocolumnar transformation zone between the endo- and ecto-cervix with various high-risk (HR) human papillomaviruses (HPVs). The decisive turning point on the way to persistent HPV infection and malignant transformation is an immune system weakened by pathobionts and oxidative stress and an injury to the cervical mucosa, often caused by sexual activities. Through these injury and healing processes, HPV viruses, hijacking activated keratinocytes, move into the basal layers of the cervical epithelium and then continue their development towards the distal prickle cell layer (Stratum spinosum). The microbial microenvironment of the cervical tissue determines the tissue homeostasis and the integrity of the protective mucous layer through the maintenance of a healthy immune and metabolic signalling. Pathological microorganisms and the resulting dysbiosis disturb this signalling. Thus, pathological inflammatory reactions occur, which manifest the HPV infection. About 90% of all women contract an HPV infection in the course of their lives. In about 10% of cases, the virus persists and cervical intra-epithelial neoplasia (CIN) develops. Approximately 1% of women with a high-risk HPV infection incur a cervical carcinoma after 10 to 20 years. In this non-systematic review article, we summarise how the sexually and microbial mediated pathogenesis of the cervix proceeds through aberrant immune and metabolism signalling via CIN to cervical carcinoma. We show how both the virus and the cancer benefit from the same changes in the immune and metabolic environment.

HIV Pathogenesis in the Human Female Reproductive Tract

PURPOSE OF REVIEW

Women remain disproportionately affected by the HIV/AIDS pandemic. The primary mechanism for HIV acquisition in women is sexual transmission, yet the immunobiological factors that contribute to HIV susceptibility remain poorly characterized. Here, we review current knowledge on HIV pathogenesis in women, focusing on infection and immune responses in the female reproductive tract (FRT).

RECENT FINDINGS

We describe recent findings on innate immune protection and HIV target cell distribution in the FRT. We also review multiple factors that modify susceptibility to infection, including sex hormones, microbiome, trauma, and how HIV risk changes during women's life cycle. Finally, we review current strategies for HIV prevention and identify barriers for research in HIV infection and pathogenesis in women. A complex network of interrelated biological and sociocultural factors contributes to HIV risk in women and impairs prevention and cure strategies. Understanding how HIV establishes infection in the FRT can provide clues to develop novel interventions to prevent HIV acquisition in women.

Prospects for mucosal vaccine: shutting the door on SARS-CoV-2

The sudden emergence of a highly transmissible and pathogenic coronavirus SARS-CoV-2 in December 2019 from China and its rapid global spread has posed an international health emergency. The rapid development of an effective vaccine is imperative to control the spread of SARS-CoV-2. A number of concurrent efforts to find an effective therapeutic agent or vaccine for COVID-19 (coronavirus disease 2019) are being undertaken globally. Oral and nasal mucosal surfaces serve as the primary portal of entry for pathogens like coronaviruses in the human body. As evidenced by studies on similar coronaviruses (SARS-CoV and MERS-CoV), mucosal vaccination can provide a safe and effective means for the induction of long-lasting systemic and mucosal immunity to confer protection against SARS-CoV-2. This article summarizes the approaches to an effective mucosal vaccine formulation which can be a rewarding approach to combat the unprecedented threat posed by this emerging global pandemic.

Flt3-L enhances trans-epithelial migration and antigen presentation of dendritic cells adoptively transferred to genital mucosa

Dendritic cells (DCs) play a critical role in shaping adaptive immunity. Systemic transfer of DCs by intravenous injection has been widely investigated to inform the development of immunogenic DCs for use as cellular therapies. Adoptive transfer of DCs to mucosal sites has been limited but serves as a valuable tool to understand the role of the microenvironment on mucosal DC activation, maturation and antigen presentation. Here, we show that chitosan facilitates transmigration of DCs across the vaginal epithelium in the mouse female reproductive tract (FRT). In addition, ex vivo programming of DCs with fms-related tyrosine kinase 3 ligand (Flt3-L) was found to enhance translocation of intravaginally administered DCs to draining lymph nodes (dLNs) and stimulate in vivo proliferation of both antigen-specific CD4+ and CD8+ T cells (cross-presentation). Mucosal priming with chitosan and DC programming may hold great promise to enhance efficacy of DC-based vaccination to the female genital mucosa.

Prostate immunology: A challenging puzzle

Mucosal immunity defines the relationship of surfaces in contact with the environment and integrates diverse tissues such as epidermis, gum, nose, gut, uterus and prostate with the immune system. Although considered part of a system, each mucosa presents specific immune features beyond the barrier and secretory functions. Information regarding the mucosal immunology of the male reproductive tract and the prostate gland in particular is scarce. In this review, we approach the prostate as an epithelial barrier and as part of the mucosal immune system. Finally, we also raise a series of questions that will improve the understanding of this gland, its role in reproduction and its sensitivity/resistance to disease.

The effect of pathophysiological changes in the vaginal milieu on the signs and symptoms of genitourinary syndrome of menopause (GSM)

IMPORTANCE AND OBJECTIVE

The aim of this study was to provide an overview of the most recent literature on genitourinary syndrome of menopause (GSM), to explore the key elements of GSM diagnosis, and the potential impact of pathophysiological changes in the vaginal milieu on vulvovaginal symptoms.

METHODS

The MEDLINE database was searched, and only articles written in English were considered. Additional references were identified by hand searching the bibliographies of the included articles.

DISCUSSIONS AND CONCLUSION

The vaginal milieu plays important roles in producing bothersome symptoms in the host. In women with GSM, low hormone states can result in pathophysiological changes in the vaginal milieu, including the vaginal microbiome and the mucosal immunity. Hormone-associated disruption of the balance of the indigenous microbiota and the dysregulation of these immune responses are the pathophysiological basis of GSM symptoms. However, whether the microbiome and mucosal immunity are markers of vulvovaginal disorder or agents actively promoting a healthy vagina are still not fully understood. It is an important area of focus.

Nanoparticle formulated vaccines: opportunities and challenges

Vaccines harness the inherent properties of the immune system to prevent diseases or treat existing ones. Continuous efforts have been devoted to both gaining a mechanistic understanding of how the immune system operates and designing vaccines with high efficacies and effectiveness. Advancements in nanotechnology in recent years have generated unique opportunities to meet the daunting challenges associated with immunology and vaccine development. Firstly, nanoparticle formulated systems provide ideal model systems for studying the operation of the immune system, making it possible to systematically identify key factors and understand their roles in specific immune responses. Also, the versatile compositions/architectures of nanoparticle systems enable new strategies/novel platforms for developing vaccines with high efficacies and effectiveness. In this review, we discuss the advantages of nanoparticles and the challenges faced during vaccine development, through the framework of the immunological mechanisms of vaccination, with the aim of bridging the gap between immunology and materials science, which are both involved in vaccine design. The knowledge obtained provides general guidelines for future vaccine development.

MUCOSAL anti-infections vaccines: Beyond conventional vaccines

An urgent search is currently underway for alternatives to antibiotics to prevent infections, due to the accelerated evolution and increase in antibiotic resistance. This problem is more serious for patients with recurrent infections, since they have to use many cycles of antibiotics per year, so the risk for antibiotic resistance is higher and can be life-threatening. In recent years, the use of prophylactic vaccines via the mucosal route for these patients with recurrent infections has been demonstrated as a potentially beneficial and safe alternative to prevent infections. The new knowledge about mucosal immunity and trained immunity, a form of innate immunity memory that can enhance the response to different infectious threads, has made it easier to extend its use. The application of the new concepts of trained immunity may explain the simultaneous pro-tolerogenic and boosting effect or effects of these drugs on diverse immune cells for different infections. In this review, we describe the immunomodulatory mechanisms of mucosal polybacterial vaccines and their connection with trained immunity and its utility in the prevention of recurrent infections in immunosuppressed patients.

The Unique Microbiome and Innate Immunity During Pregnancy

A successful pregnancy depends on not only the tolerance of the fetal immune system by the mother but also resistance against the threat of hazardous microorganisms. Infection with pathogenic microorganisms during pregnancy may lead to premature delivery, miscarriage, growth restriction, neonatal morbidity, and other adverse outcomes. Moreover, the host also has an intact immune system to avoid these adverse outcomes. It is important to note the presence of normal bacteria in the maternal reproductive tract and the principal role of the maternal-placental-fetal interaction in antimicrobial immunity. Previous studies mainly focused on maternal infection during pregnancy. However, this review summarizes the new views on the study of the maternal microbiome and expounds the innate immune defense mechanism of the maternal vagina and decidua as well as how cytotrophoblasts and syncytiotrophoblasts recognize and kill bacteria in the placenta. Fetal immune systems, thought to be weak, also exhibit an immune defense function that is indispensable for maintaining the safety of the fetus. The skin, lungs, and intestines of the fetus during pregnancy constitute the main immune barriers. These findings will provide a new understanding of the effects of normal microbial flora and how the host resists harmful microbes during pregnancy. We believe that it may also contribute to the reference on the clinical prevention and treatment of gestational infection to avoid adverse pregnancy outcomes.

Immune responses in the human female reproductive tract

Mucosal surfaces are key interfaces between the host and its environment, but also constitute ports of entry for numerous pathogens. The gut and lung mucosae act as points of nutrient and gas exchange, respectively, but the physiological purpose of the female reproductive tract (FRT) is to allow implantation and development of the fetus. Our understanding of immune responses in the FRT has traditionally lagged behind our grasp of the situation at other mucosal sites, but recently reproductive immunologists have begun to make rapid progress in this challenging area. Here, we review current knowledge of immune responses in the human FRT and their heterogeneity within and between compartments. In the commensal-rich vagina, the immune system must allow the growth of beneficial microbes, whereas the key challenge in the uterus is allowing the growth of the semi-allogeneic fetus. In both compartments, these objectives must be balanced with the need to eliminate pathogens. Our developing understanding of immune responses in the FRT will help us develop interventions to prevent the spread of sexually transmitted diseases and to improve outcomes of pregnancy for mothers and babies.

A role for the CCR5-CCL5 interaction in the preferential migration of HSV-2-specific effector cells to the vaginal mucosa upon nasal immunization

Our current study focused on elucidating the role of specific chemokine-receptor interactions in antigen (Ag)-specific immune cell migration from nasal to genital mucosal tissues. This cellular migration is critical to induce effective Ag-specific immune responses against sexually transmitted genital infections. In this study, nasal immunization with live attenuated HSV-2 TK^- induced the upregulation of CCR5 expression in effector immune cells, including CD4⁺ T cells, in Ag-priming sites and vaginal tissue. The CCR5 ligands CCL3, CCL4, and CCL5 all showed upregulated expression in vaginal tissue; in particular, CCL5 expression was highly enhanced in the stromal cells of vaginal tissue after nasal immunization. Intravaginal blockade of CCL5 by using neutralizing antibody diminished the number of HSV-2-specific effector cells in the vagina. Furthermore, loss of CCR5, a receptor for CCL5, impaired the migration of nasally primed Ag-specific effector cells from the airway to vagina. Effector cells adoptively transferred from CCR5-deficient mice failed to migrate into vaginal tissue, consequently increasing recipient mice's susceptibility to HSV-2 vaginal infection. These results indicate that the CCR5-CCL5 chemokine pathway is required for the migration and retention of nasally primed Ag-specific effector cells in vagina for providing protective immunity against HSV-2 infection.

Low expression of RNA sensors impacts Zika virus infection in the lower female reproductive tract

Innate immune responses to Zika virus (ZIKV) are dampened in the lower female reproductive tract (LFRT) compared to other tissues, but the mechanism that underlies this vulnerability is poorly understood. Using tissues from uninfected and vaginally ZIKV-infected macaques and mice, we show that low basal expression of RNA-sensing pattern recognition receptors (PRRs), or their co-receptors, in the LFRT contributes to high viral replication in this tissue. In the LFRT, ZIKV sensing provides limited protection against viral replication, and the sensors are also minimally induced after vaginal infection. While IFNα/β receptor signaling offers minimal protection in the LFRT, it is required to prevent dissemination of ZIKV to other tissues, including the upper FRT. Our findings support a role for RNA-sensing PRRs in the dampened innate immunity against ZIKV in the LFRT compared to other tissues and underlie potential implications for systemic dissemination upon heterosexual transmission of ZIKV in women.

T Cells in the Female Reproductive Tract Can Both Block and Facilitate HIV Transmission

Because HIV is sexually transmitted, there is considerable interest in defining the nature of anti-HIV immunity in the female reproductive tract (FRT) and in developing ways to elicit antiviral immunity in the FRT through vaccination. Although it is assumed that the mucosal immune system of the FRT is of central importance for protection against sexually transmitted diseases, including HIV, this arm of the immune system has only recently been studied. Here we provide a brief review of the role of T cells in the FRT in blocking and facilitating HIV transmission.

Tissue-Specific Control of Tissue-Resident Memory T Cells

Tissue-resident memory T (TRM) cells have emerged as a major component of T cell biology. Recent investigations have greatly advanced our understanding of TRMs. Common features have been discovered to distinguish memory T cells residing in various mucosal and non-mucosal tissues from their circulating counterparts. Given that most organs and tissues contain a unique microenvironment, local signal-induced tissue-specific features are tightly associated with the differentiation, homeostasis, and protective functions of TRMs. Here, we discuss recent advances in the TRM field with a special emphasis on the interaction between local signals and TRMs in the context of individual tissue environment.

Innate Sensing of DNA Virus Genomes

DNA viruses are linked to many infectious diseases and contribute significantly to human morbidity and mortality worldwide. Moreover, DNA viral infections are usually lifelong and hard to eradicate. Under certain circumstances, these viruses can cause fatal disease, especially in children and immunocompromised patients. An efficient innate immune response against these viruses is critical, not only as the first line of host defense against viral infection but also for mounting more specific and robust adaptive immunity against the virus. Recognition of the viral DNA genome is the very first step of this whole process and is crucial for understanding viral pathogenesis as well as for preventing and treating DNA virus-associated diseases. This review focuses on the current state of our knowledge on how human DNA viruses are sensed by the host innate immune system and how viral proteins counteract this immune response.

Fucosylated umbilical cord blood hematopoietic stem cell expansion on selectin-coated scaffolds

Despite the advantages of transplantation of umbilical cord blood's (UCB's) hematopoietic stem cells (uHSCs) for hematologic malignancy treatment, there are two major challenges in using them: (a) Insufficient amount of uHSCs in a UCB unit; (b) a defect in uHSCs homing to bone marrow (BM) due to loose binding of their surface glycan ligands to BM's endothelium selectin receptors. To overcome these limitations, after poly l-lactic acid (PLLA) scaffold establishment and incubation of uHSCs with fucosyltransferase-VI and GDP-fucose, ex vivo expansion of these cells on selectin-coated scaffold was done. The characteristics of the cultured fucosylated and nonfucosylated cells on a two-dimensional culture system, PLLA, and a selectin-coated scaffold were evaluated by flow cytometry, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, colony-forming unit (CFU) assay, and CXCR4 expression at the messenger RNA and protein levels. According to the findings of this study, optimized attachment to the scaffold in scanning electron microscopy micrograph, maximum count of CFU, and the highest 570 nm absorption were observed in fucosylated cells expanded on selectin-coated scaffolds. Furthermore, real-time polymerase chain reaction showed the highest expression of the CXCR4 gene, and immunocytochemistry data confirmed that the CXCR4 protein was functional in this group compared with the other groups. Considered together, the results showed that selectin-coated scaffold could be a supportive structure for fucosylated uHSC expansion and homing by nanotopography. Fucosylated cells placed on the selectin-coated scaffold serve as a basal surface for cell-cell interaction and more homing potential of uHSCs. Accordingly, this procedure can also be considered as a promising technique for the hematological disorder treatment and tissue engineering applications.

Dendritic Cells From the Cervical Mucosa Capture and Transfer HIV-1 via Siglec-1

Antigen presenting cells from the cervical mucosa are thought to amplify incoming HIV-1 and spread infection systemically without being productively infected. Yet, the molecular mechanism at the cervical mucosa underlying this viral transmission pathway remains unknown. Here we identified a subset of HLA-DR⁺ CD14⁺ CD11c⁺ cervical DCs at the lamina propria of the ectocervix and the endocervix that expressed the type-I interferon inducible lectin Siglec-1 (CD169), which promoted viral uptake. In the cervical biopsy of a viremic HIV-1⁺ patient, Siglec-1⁺ cells harbored HIV-1-containing compartments, demonstrating that in vivo, these cells trap viruses. Ex vivo, a type-I interferon antiviral environment enhanced viral capture and trans-infection via Siglec-1. Nonetheless, HIV-1 transfer via cervical DCs was effectively prevented with antibodies against Siglec-1. Our findings contribute to decipher how cervical DCs may boost HIV-1 replication and promote systemic viral spread from the cervical mucosa, and highlight the importance of including inhibitors against Siglec-1 in microbicidal strategies.

Mucosal Immunity in HIV/SIV Infection: T Cells, B Cells and Beyond

As our understanding of mucosal immunity increases, it is becoming clear that the host response to HIV-1 is more complex and nuanced than originally believed. The mucosal landscape is populated with a variety of specialized cell types whose functions include combating infectious agents while preserving commensal microbiota, maintaining barrier integrity, and ensuring immune homeostasis. Advances in multiparameter flow cytometry, gene expression analysis and bioinformatics have allowed more detailed characterization of these cell types and their roles in host defense than was previously possible. This review provides an overview of existing literature on immunity to HIV-1 and SIVmac in mucosal tissues of the female reproductive tract and the gastrointestinal tract, focusing on major effector cell populations and briefly summarizing new information on tissue resident memory T cells, T_reg, Th17, Th22 and innate lymphocytes (ILC), subsets that have been studied primarily in the gastrointestinal mucosa.

Preclinical Safety Evaluation of HIV-1 gp120 Responsive Microbicide Delivery System in C57BL/6 Female Mice

Many novel vaginal/rectal microbicide formulations failed clinically due to safety concerns, indicating the need for the early investigation of lead microbicide formulations. In this study, the preclinical safety of an HIV-1 gp120 and mannose responsive microbicide delivery system (MRP) is evaluated in C57BL/6 mice. MRP was engineered through the layer-by-layer coating of calcium carbonate (CaCO₃) with Canavalia ensiformis lectin (Con A) and glycogen. MRP mean particle diameter and zeta potential were 857.8 ± 93.1 nm and 2.37 ± 4.12 mV, respectively. Tenofovir (TFV) encapsulation and loading efficiencies in MRP were 70.1% and 16.3% w/w, respectively. When exposed to HIV-1 rgp120 (25 μg/mL), MRP released a significant amount of TFV (∼5-fold higher) in vaginal and seminal fluid mixture compared to the control (pre-exposure) level (∼59 μg/mL) in vaginal fluid alone. Unlike the positive control treated groups (e.g., nonoxynol-9), no significant histological damages and CD45+ cells infiltration were observed in the vaginal and major reproductive organ epithelial layers. This was probably due to MRP biocompatibility and its isosmolality (304.33 ± 0.58 mOsm/kg). Furthermore, compared to negative controls, there was no statistically significant increase in pro-inflammatory cytokines such as IL1α, Ilβ, IL7, IP10, and TNFα. Collectively, these data suggest that MRP is a relatively safe nanotemplate for HIV-1 gp120 stimuli responsive vaginal microbicide delivery system.

Evaluation of Mucosal Humoral and Cellular Immune Responses to HIV in External Secretions and Mucosal Tissues

The mucosal immune systems of the genital and intestinal tracts as the most frequent sites of HIV-1 entry, display remarkable immunological differences from the systemic immune compartment which must be considered in the evaluation of humoral and cellular immune responses to HIV-1. Marked differences in the fluids from the genital and intestinal tracts and in plasma with respect to the Ig isotypes, their levels, molecular forms and distinct effector functions must be taken into consideration in the evaluation and interpretation of humoral immune responses. Because of the low levels and highly pronounced variation in Ig content, HIV-1-specific antibody concentrations should be always related to the levels of total Ig of a given isotype. This practice will avoid inevitable differences due to the small volumes of collected fluids and sample dilution during the collection and processing of samples from external secretions. Furthermore, appropriate controls and immunochemical assays should be used to complement and confirm results generated by ELISA, which is prone to false positivity. In the evaluation of antibody-mediated virus neutralization in external secretions, precautions and rigorous controls must be used to exclude the effect of innate humoral factors. The evaluation of cell-mediated immune responses in mucosal tissues is difficult due to the low yields of cells obtained from tissue biopsies or cytobrush scrapings. Furthermore, tissue biopsies of, for example rectal mucosa, provide information pertinent exclusively to this local site, which due to the differences in distribution of cells of different phenotypes, do not provide information generalized to the entire intestinal tract. Importantly, studies concerning the kinetics of cellular responses are difficult to perform due to the limited availability of samples or to the inability of obtaining frequent repeated tissue biopsies. For sampling the female genital tract parallel collection of menstrual and peripheral blood yields high numbers of cells that permit their detailed phenotypic and functional analyses. In contrast to tissue biopsies, this non-traumatic collection procedure, results in high cell yields and repeated monthly sampling permits extensive and parallel functional studies of kinetics and unique characteristics of HIV-1-specific cellular responses in the female genital tract and peripheral blood.

Host Defenses to Viruses

Virus infections continue to pose a substantial threat to human health. Unravelling the intricacies of immune defenses against viruses should lead to improved control of infections through the design of new vaccines and therapies. Our understanding of the fundamental cellular and molecular mechanisms involved in the immune systems response to virus infection has improved substantially in recent years. This wealth of new information and the promise of new insight from systems biology approaches continue to drive research in this field. Such knowledge has revealed why viruses sometimes induce immune dysfunction or trigger disastrous pathology and has paved the way for new therapies being tested against chronic and emerging infections. In this chapter, we briefly summarize the general concepts in immunity to virus infections and highlight some of the key challenges remaining for the future. Virus infections continue to pose a substantial threat to human health.

Th17 response in patients with cervical cancer

Persistent infection by high-risk human papillomavirus (HR-HPV) is the main risk factor for uterine cervical cancer (UCC). However, viral infection alone is not sufficient for the development and progression of premalignant cervical lesions for cancer. In previous years it has been suggested that the adaptive immune response triggered by the differentiation of naïve helper T cells in Th17 cells may serve an important role in disease development. It has been hypothesized that Th17 cells may be involved in the promotion of UCC, as high levels of interleukin 17 (IL17) expression have been detected in the mucosa of the uterine cervix of patients affected by the disease. However, the role of Th17 cells in the tumor development and progression remains unclear. It is believed that the immune response of the Th17 type during persistent infection of the genital tract with HR-HPV triggers chronic inflammation with a long duration with the production of IL17 and other pro-inflammatory cytokines, creating a favorable environment for tumor development. These cytokines are produced by immune system cells in addition to tumor cells and appear to function by modulating the host immune system, resulting in an immunosuppressive response as opposed to inducing an effective protective immune response, thus contributing to the growth and progression of the tumor. In the present review, the latest advances are presented about the function of Th17 cells and the cytokines produced by them in the development and progression of UCC.

Comparative Genomic and Phenotypic Analysis of the Vaginal Probiotic Lactobacillus rhamnosus GR-1

Lactobacillus represents a versatile bacterial genus, which can adapt to a wide variety of ecological niches, including human body sites such as the intestinal and urogenital tract. In this study, the complete genome sequence of the vaginal probiotic Lactobacillus rhamnosus GR-1 was determined and compared to other L. rhamnosus strains at genomic and phenotypic level. The strain GR-1 was originally isolated from a female urethra, and was assessed with L. rhamnosus GG from a feces sample of a healthy male, and L. rhamnosus LC705 from a dairy product. A key difference is the absence in GR-1 and LC705 of the spaCBA locus required for pili-mediated intestinal epithelial adhesion. In addition, the L. rhamnosus GR-1 genome contains a unique cluster for exopolysaccharide production, which is postulated to synthesize glucose-rich, rhamnose-lacking exopolysaccharide molecules that are different from the galactose-rich extracellular polysaccharide of L. rhamnosus GG. Compared to L. rhamnosus GG, L. rhamnosus GR-1 was also genetically predicted and experimentally shown to better metabolize lactose and maltose, and to better withstand oxidative stress, which is of relevance in the vagina. This study could thus provide a molecular framework for the selection of the optimal probiotic strain for each targeted niche and condition, but further substantiation of niche adaptation mechanisms of lactobacilli is warranted.

Aging impacts CD103+ CD8+ T cell presence and induction by dendritic cells in the genital tract

As women age, susceptibility to systemic and genital infections increases. Tissue-resident memory T cells (TRMs) are CD103⁺ CD8⁺ long-lived lymphocytes that provide critical mucosal immune protection. Mucosal dendritic cells (DCs) are known to induce CD103 expression on CD8⁺ T cells. While CD103⁺ CD8⁺ T cells are found throughout the female reproductive tract (FRT), the extent to which aging impacts their presence and induction by DCs remains unknown. Using hysterectomy tissues, we found that endometrial CD103⁺ CD8⁺ T cells were increased in postmenopausal compared to premenopausal women. Endometrial DCs from postmenopausal women were significantly more effective at inducing CD103 expression on allogeneic naïve CD8⁺ T cells than DCs from premenopausal women; CD103 upregulation was mediated through membrane-bound TGFβ signaling. In contrast, cervical CD103⁺ T cells and DC numbers declined in postmenopausal women with age. Decreases in DCs correlated with decreased CD103⁺ T cells in endocervix, but not ectocervix. Our findings demonstrate a previously unrecognized compartmentalization of TRMs in the FRT of postmenopausal women, with loss of TRMs and DCs in the cervix with aging, and increased TRMs and DC induction capacity in the endometrium. These findings are relevant to understanding immune protection in the FRT and to the design of vaccines for women of all ages.

Niches for the Long-Term Maintenance of Tissue-Resident Memory T Cells

Tissue-resident memory T cells (T_RM cells) are a population of immune cells that reside in the lymphoid and non-lymphoid organs without recirculation through the blood. These important cells occupy and utilize unique anatomical and physiological niches that are distinct from those for other memory T cell populations, such as central memory T cells in the secondary lymphoid organs and effector memory T cells that circulate through the tissues. CD8⁺ T_RM cells typically localize in the epithelial layers of barrier tissues where they are optimally positioned to act as sentinels to trigger antigen-specific protection against reinfection. CD4⁺ T_RM cells typically localize below the epithelial layers, such as below the basement membrane, and cluster in lymphoid structures designed to optimize interactions with antigen-presenting cells upon reinfection. A key feature of T_RM populations is their ability to be maintained in barrier tissues for prolonged periods of time. For example, skin CD8⁺ T_RM cells displace epidermal niches originally occupied by γδ T cells, thereby enabling their stable persistence for years. It is also clear that the long-term maintenance of T_RM cells in different microenvironments is dependent on multiple tissue-specific survival cues, although the specific details are poorly understood. However, not all T_RM persist over the long term. Recently, we identified a new spatial niche for the maintenance of CD8⁺ T_RM cells in the lung, which is created at the site of tissue regeneration after injury [termed repair-associated memory depots (RAMD)]. The short-lived nature of RAMD potentially explains the short lifespans of CD8⁺ T_RM cells in this particular tissue. Clearly, a better understanding of the niche-dependent maintenance of T_RM cells will be important for the development of vaccines designed to promote barrier immunity. In this review, we discuss recent advances in our understanding of the properties and nature of tissue-specific niches that maintain T_RM cells in different tissues.

Laser Adjuvant-Assisted Peptide Vaccine Promotes Skin Mobilization of Dendritic Cells and Enhances Protective CD8+ TEM and TRM Cell Responses against Herpesvirus Infection and Disease

There is an urgent need for chemical-free and biological-free safe adjuvants to enhance the immunogenicity of vaccines against widespread viral pathogens, such as herpes simplex virus 2 (HSV-2), that infect a large proportion of the world human population. In the present study, we investigated the safety, immunogenicity, and protective efficacy of a laser adjuvant-assisted peptide (LAP) vaccine in the B6 mouse model of genital herpes. This LAP vaccine and its laser-free peptide (LFP) vaccine analog contain the immunodominant HSV-2 glycoprotein B CD8⁺ T cell epitope (HSV-gB_498-505) covalently linked with the promiscuous glycoprotein D CD4⁺ T helper cell epitope (HSV-gD_49-89). Prior to intradermal delivery of the LAP vaccine, the lower-flank shaved skin of B6 or CD11c/eYFP transgenic mice received a topical skin treatment with 5% imiquimod cream and then was exposed for 60 s to a laser, using the FDA-approved nonablative diode. Compared to the LFP vaccine, the LAP vaccine (i) triggered mobilization of dendritic cells (DCs) in the skin, which formed small spots along the laser-treated areas, (ii) induced phenotypic and functional maturation of DCs, (iii) stimulated long-lasting HSV-specific effector memory CD8⁺ T cells (T_EM cells) and tissue-resident CD8⁺ T cells (T_RM cells) locally in the vaginal mucocutaneous tissues (VM), and (iv) induced protective immunity against genital herpes infection and disease. As an alternative to currently used conventional adjuvants, the chemical- and biological-free laser adjuvant offers a well-tolerated, simple-to-produce method to enhance mass vaccination for widespread viral infections.IMPORTANCE Herpes simplex viruses 1 and 2 (HSV-1 and HSV-2) infect a large proportion of the world population. There is an urgent need for chemical-free and biological-free safe adjuvants that would advance mass vaccination against the widespread herpes infections. The present study demonstrates that immunization with a laser-assisted herpes peptide vaccine triggered skin mobilization of dendritic cells (DCs) that stimulated strong and long-lasting HSV-specific effector memory CD8⁺ T cells (T_EM cells) and tissue-resident CD8⁺ T cells (T_RM cells) locally in the vaginal mucocutaneous tissues. The induced local CD8⁺ T cell response was associated with protection against genital herpes infection and disease. These results draw attention to chemical- and biological-free laser adjuvants as alternatives to currently used conventional adjuvants to enhance mass vaccination for widespread viral infections, such as those caused by HSV-1 and HSV-2.

Lipid-Based Particles: Versatile Delivery Systems for Mucosal Vaccination against Infection

Vaccination is the process of administering immunogenic formulations in order to induce or harness antigen (Ag)-specific antibody and T cell responses in order to protect against infections. Important successes have been obtained in protecting individuals against many deleterious pathological situations after parenteral vaccination. However, one of the major limitations of the current vaccination strategies is the administration route that may not be optimal for the induction of immunity at the site of pathogen entry, i.e., mucosal surfaces. It is now well documented that immune responses along the genital, respiratory, or gastrointestinal tracts have to be elicited locally to ensure efficient trafficking of effector and memory B and T cells to mucosal tissues. Moreover, needle-free mucosal delivery of vaccines is advantageous in terms of safety, compliance, and ease of administration. However, the quest for mucosal vaccines is challenging due to (1) the fact that Ag sampling has to be performed across the epithelium through a relatively limited number of portals of entry; (2) the deleterious acidic and proteolytic environment of the mucosae that affect the stability, integrity, and retention time of the applied Ags; and (3) the tolerogenic environment of mucosae, which requires the addition of adjuvants to elicit efficient effector immune responses. Until now, only few mucosally applicable vaccine formulations have been developed and successfully tested. In animal models and clinical trials, the use of lipidic structures such as liposomes, virosomes, immune stimulating complexes, gas-filled microbubbles and emulsions has proven efficient for the mucosal delivery of associated Ags and the induction of local and systemic immune reponses. Such particles are suitable for mucosal delivery because they protect the associated payload from degradation and deliver concentrated amounts of Ags via specialized sampling cells (microfold cells) within the mucosal epithelium to underlying antigen-presenting cells. The review aims at summarizing recent development in the field of mucosal vaccination using lipid-based particles. The modularity ensured by tailoring the lipidic design and content of particles, and their known safety as already established in humans, make the continuing appraisal of these vaccine candidates a promising development in the field of targeted mucosal vaccination.

Circulating pathogen-specific plasmablasts in female patients with upper genital tract infection

Mucosal antibodies constitute the first line of adaptive immune defence against invaders in the female genital tract (FGT), yet the sequence of events leading to their production is surprisingly poorly characterized. We explored the induction of pathogen-specific antibody-secreting cells (ASC) as a response to an acute infection in the upper FGT. We recruited 12 patients undergoing surgery due to an upper FGT infection (7/12 blood culture positive, 5/12 negative) and six healthy controls. Pathogens were sampled during surgery and PBMC collected in the acute phase of the disease (days 7-10). We searched by ELISPOT circulating pathogen-specific ASC and explored their frequency, immunoglobulin isotype distribution, and expressions of homing receptors (α₄β_7, L-selectin, and CLA). All patients had circulating ASC specific to the infective bacteria; the geometric mean was 434 (95%CI 155-1234) ASC (IgA + IgG + IgM)/10⁶ PBMC. IgA ASC predominated in 7/12, IgG ASC in 3/12, and IgM ASC in 2/12 cases. Of all the pathogen-specific ASC, 60% expressed α₄β₇, 67% L-selectin, and 9% CLA. This study is the first to show induction of pathogen-specific ASC in the peripheral blood in bacterial infection in the human FGT. Our findings reveal that such FGT-originating pathogen-specific ASC are predominated by IgA ASC and exhibit a homing receptor profile resembling that of ASC in acute urinary tract infection. The data thus suggest a characteristic profile shared by the urogenital tract.

Seminal vesicle fluid increases the efficacy of intravaginal HSV-2 vaccination

Once considered merely as a vehicle for spermatozoa, it is now clear that seminal plasma (SP) induces a variety of biological actions on the female reproductive tissues able to modulate the immune response against paternal antigens. To our knowledge, the influence of SP on the immune response against sexually transmitted pathogens has not been yet evaluated. We here analyzed whether the seminal vesicle fluid (SVF), which contributes almost 60% of the SP volume in mice, could modulate the immune response against herpes simplex virus type 2 (HSV-2). We found that SVF does not modify the course of primary infection, but markedly improved protection conferred by vaginal vaccination with inactivated HSV-2 against a lethal challenge. This protective effect was shown to be associated to a robust memory immune response mediated by CD4+ and CD8+ T cells in both the lymph nodes draining the vagina and the vaginal mucosa, the site of viral replication. In contrast with the widespread notion that SP acts as an immunosuppressive agent, our results suggest that SVF might improve the female immune response against sexually transmitted pathogens.

The Human Penis Is a Genuine Immunological Effector Site

The human penis is a main portal of entry for numerous pathogens, and vaccines able to control resulting infections locally are highly desirable. However, in contrast to the gastrointestinal or vaginal mucosa, the penile immune system and mechanisms inducing a penile immune response remain elusive. In this descriptive study, using multiparametric flow cytometry and immunohistochemistry, we characterized mucosal immune cells such as B, T, and natural killer (NK) cells from the urethra, fossa, and glans of human adult penile tissues. We show that memory B lymphocytes and CD138⁺ plasma cells are detected in all penile compartments. CD4⁺ and CD8⁺ T lymphocytes reside in the epithelium and lamina propria of the penile regions and have mostly a resting memory phenotype. All penile regions contain CD56^dim NK cells surface expressing the natural cytotoxicity receptor NKp44 and the antibody-dependent cell cytotoxicity receptor CD16. These cells are also able to spontaneously secrete pro- and anti-inflammatory cytokines, such as IL-17 and IL-22. Finally, CCR10 is the main homing receptor detected in these penile cells although, together with CCR3, CCR6, and CCR9, their expression level differs between penile compartments. Unlike antigen-presenting cells which type differ between penile regions as we reported earlier, urethral, fossa, and glans content in immune B, T, and NK cells is comparable. However, median values per each analysis suggest that the glans, containing higher number and more activated NK cells together with higher number of terminally differentiate effector CD8⁺ T cells, is a superior effector site than the urethra and the fossa. Thus, the human penis is an immunologically active tissue containing the cellular machinery required to induce and produce a specific and effective response against mucosal pathogens. It can therefore be considered as a classic mucosal effector site, a feature that must be taken into account for the elaboration of efficient strategies, including vaccines, against sexually transmitted infections.

The origin of prostate gland-secreted IgA and IgG

The prostate secretes immunoglobulin (Ig) A (IgA) and IgG; however, how immunoglobulins reach the secretion, where the plasma cells are located, whether immunoglobulins are antigen-specific and where activation of the adaptive response occurs are still unknown. Immune cells, including CD45RA⁺ cells, were scattered in the stroma and not organized mucosae-associated lymphoid-tissue. IgA (but not IgG) immunostaining identified stromal plasma cells and epithelial cells in non-immunized rats. Injected tetramethylrhodamine-IgA transcytosed the epithelium along with polymeric immunoglobulin receptor. Oral immunization with ovalbumin/mesopourous SBA-15 silica adjuvant resulted in more stromal CD45RA⁺/IgA⁺ cells, increased content of ovalbumin-specific IgA and IgG, and the appearance of intraepithelial CD45RA⁺/IgG⁺ cells. An increased number of dendritic cells that cooperate in other sites with transient immunocompetent lymphocytes, and the higher levels of interleukin-1β, interferon-γ and transforming growth factor-β, explain the levels of specific antibodies. Nasal immunization produced similar results except for the increase in dendritic cells. This immunomodulatory strategy seems useful to boost immunity against genitourinary infections and, perhaps, cancer.