Maternal schistosomiasis impairs offspring Interleukin-4 production and B cell expansion

Schistosomiasis Chemotherapy, Chemoprevention, and Vaccines: History, Progress, and Priorities

BACKGROUND

Schistosomiasis is a major human disease of public health importance. Freshwater snails serving as intermediary hosts and human interaction with surface water tainted by feces or urine are both necessary components of the transmission cycle. Schistosoma haematobium, Schistosoma mansoni, and Schistosoma japonicum are the primary pathogen species. Over 250 million individuals are infected globally, according to the World Health Organization, causing significant morbidity and an estimated loss of 1.9 million disability-adjusted life years, a number that is probably underestimated. Immunological protection is slowly built up through complex immunological systems, although innate factors also play a role. Chronic schistosomiasis affects mainly individuals residing in poor rural area. Vaccination is considered as one of the most sustainable options for the control of any pathogen, but schistosomiasis vaccine for humans or animals is not available till now despite the discovery of numerous potentially promising schistosome vaccine antigens.

OBJECTIVE

To provide an overview of the schistosomiasis chemotherapy, chemoprevention, and vaccines history and progress.

DESIGN

Review article.

DATA SOURCES

PubMed, ISI Web of Science, Science Direct, and the World Health Organization database.

CONCLUSION

Favorably praziquantel (PZQ) is a medication with excellent chemopreventive treatment compliance. Due to the extensive usage of PZQ, there is a great deal of debate surrounding the emergence of drug resistance. PZQ is effective against all species of schistosomes, schistosomiasis prevalence has remained largely unaffected, due to reinfection in high transmission areas and growing juvenile worms that were not affected by the drug, even though the need for a schistosomiasis vaccine is even more pressing.

Maternal Helminth Infection Causes Dysfunctional B Cell Development in Male Offspring

Infections during pregnancy are known to trigger alterations in offspring immunity, often leading to increased disease susceptibility. Maternal helminth infections correlate with lower Ab titers to certain childhood immunizations and putative decreased vaccine efficacy. The mechanisms that underlie how maternal infection blunts offspring humoral responses are unclear. Using our murine model of maternal schistosomiasis, we found that maternal helminth infection decreases the germinal center response of all offspring to tetanus immunization. However, only male offspring have defects in memory B cell and long-lived plasma cell generation. We found this sex-specific aberration begins during B cell development within the bone marrow via alteration of the IL-7 niche and persists throughout antigenic activation in the germinal center in the periphery. Critically, these defects in males are cell intrinsic, persisting following adoptive transfer to control male pups. Together, these data show that maternal infections can alter both the bone marrow microenvironment and the development of B lymphocytes in a sex-specific manner. This study correlates maternal infection induced defects in early life B cell development with ineffective Ab responses after vaccination.

How does geographical diversity shape vaccine efficacy?

Vaccination is a cornerstone of public health, saving millions of lives each year by preventing a variety of infectious diseases. Yet, despite global vaccination efforts, emerging research highlights significant geographical disparities in vaccine efficacy and immunogenicity. These variations underscore the critical interplay between immunological factors and environmental, genetic, and nutritional elements across different populations. Our review article aimed to explore the multifactorial reasons behind geographical variations in vaccine efficacy. Also, this study has shown how important host factors like age, obesity, gender, and genetic diversity, especially within the major histocompatibility complex, are in determining how well a vaccine works. Nutritional status, namely deficiencies in micronutrients such as vitamins and zinc, and lifestyle factors including stress, sleep, alcohol consumption, and physical activity are also shown to have profound effects on vaccine-induced immunity. Importantly, our paper also brought to light the influence of microbial and ecological factors, such as the gut microbiome and environmental pollutants, on the immune system's response to vaccination. The findings emphasize the importance of tailoring vaccination strategies to accommodate the unique immunological landscapes shaped by geographical and societal factors. This tailored approach could enhance vaccine efficacy, reduce disparities in vaccine response, and ultimately contribute to the global fight against infectious diseases.

B Cells Influence Encephalitogenic T Cell Frequency to Myelin Oligodendrocyte Glycoprotein (MOG)38-49 during Full-length MOG Protein-Induced Demyelinating Disease

Although T cells are encephalitogenic during demyelinating disease, B cell-depleting therapies are a successful treatment for patients with multiple sclerosis. Murine models of demyelinating disease utilizing myelin epitopes, such as myelin oligodendrocyte glycoprotein (MOG)35-55, induce a robust CD4 T cell response but mitigate the contribution of pathological B cells. This limits their efficacy for investigating how B cell depletion affects T cells. Furthermore, induction of experimental autoimmune encephalomyelitis with a single CD4 T cell epitope does not reflect the breadth of epitopes observed in the clinic. To better model the adaptive immune response, mice were immunized with the full-length MOG protein or the MOG1-125 extracellular domain (ECD) and compared with MOG35-55. Mature MOG-reactive B cells were generated only by full-length MOG or ECD. The CNS-localized T cell response induced by full-length MOG is characterized by a reduction in frequency and the percentage of low-affinity T cells with reactivity toward the core epitope of MOG35-55. B cell depletion with anti-CD20 before full-length MOG-induced, but not ECD-induced, demyelinating disease restored T cell reactivity toward the immunodominant epitope of MOG35-55, suggesting the B cell-mediated control of encephalitogenic epitopes. Ultimately, this study reveals that anti-CD20 treatment can influence T cell epitopes found in the CNS during demyelinating disease.

Maternal infection causes dysfunctional BCR signaling in male offspring due to aberrant Xist expression

Infections during pregnancy with pathogens such as helminths correlate with altered immune responses to common childhood immunizations. However, the molecular mechanisms that underlie this remain unknown. Using our murine model of maternal schistosomiasis, when immunized, males from infected mothers had a lower frequency of antigen-specific germinal center B cells and downregulation of transcripts downstream of BCR signaling compared to males from uninfected mothers. This is driven by a reduction in developing B cell populations within the bone marrow of pups from infected mothers. Males from infected mothers were impacted to a greater extent than their female littermate counterparts. We found this defect to be caused by aberrant expression of the long non-coding RNA Xist in males leading to dysregulated Igα expression on developing B cells. This, for the first time, links dysfunctional BCR signaling with Xist expression, while also proposing a detrimental function for Xist expression in males.

Praziquantel Reduces Maternal Mortality and Offspring Morbidity by Enhancing Anti-Helminthic Immune Responses

Alongside the wide distribution throughout sub Saharan Africa of schistosomiasis, the morbidity associated with this chronic parasitic disease in endemic regions is often coupled with infection-driven immunomodulatory processes which modify inflammatory responses. Early life parasite exposure is theorized to drive immune tolerance towards cognate infection as well as bystander immune responses, beginning with in utero exposure to maternal infection. Considering that 40 million women of childbearing-age are at risk of infection worldwide, treatment with Praziquantel during pregnancy as currently recommended by WHO could have significant impact on disease outcomes in these populations. Here, we describe the effects of anthelminthic treatment on parasite-induced changes to fetomaternal cross talk in a murine model of maternal schistosomiasis. Praziquantel administration immediately prior to mating lead to clear re-awakening of maternal anti-parasite immune responses, with persistent maternal immune activation that included enhanced anti-schistosome cytokine responses. Clearance of parasites also improved capacity of dams to endure the additional pressure of pregnancy during infection. Maternal treatment also drove lasting functional alterations to immune system development of exposed offspring. Prenatal anthelminthic treatment skewed offspring immune responses towards parasite clearance and reduced morbidity during cognate infection. Maternal treatment also restored offspring protective IgE antibody responses directed against schistosome antigens, which were otherwise suppressed following exposure to untreated maternal infection. This was further associated with enhanced anti-schistosome cytokine responses from treatment-exposed offspring during infection. In the absence of cognate infection, exposed offspring further demonstrated imprinting across cellular populations. We provide further evidence that maternal treatment can restore a more normalized immune profile to such offspring exposed in utero to parasite infection, particularly in B cell populations, which may underlie improved responsiveness to cognate infection, and support the WHO recommendation of anthelminthic treatment during pregnancy.

The Road to Elimination: Current State of Schistosomiasis Research and Progress Towards the End Game

The new WHO Roadmap for Neglected Tropical Diseases targets the global elimination of schistosomiasis as a public health problem. To date, control strategies have focused on effective diagnostics, mass drug administration, complementary and integrative public health interventions. Non-mammalian intermediate hosts and other vertebrates promote transmission of schistosomiasis and have been utilized as experimental model systems. Experimental animal models that recapitulate schistosomiasis immunology, disease progression, and pathology observed in humans are important in testing and validation of control interventions. We discuss the pivotal value of these models in contributing to elimination of schistosomiasis. Treatment of schistosomiasis relies heavily on mass drug administration of praziquantel whose efficacy is comprised due to re-infections and experimental systems have revealed the inability to kill juvenile schistosomes. In terms of diagnosis, nonhuman primate models have demonstrated the low sensitivity of the gold standard Kato Katz smear technique. Antibody assays are valuable tools for evaluating efficacy of candidate vaccines, and sera from graded infection experiments are useful for evaluating diagnostic sensitivity of different targets. Lastly, the presence of Schistosomes can compromise the efficacy of vaccines to other infectious diseases and its elimination will benefit control programs of the other diseases. As the focus moves towards schistosomiasis elimination, it will be critical to integrate treatment, diagnostics, novel research tools such as sequencing, improved understanding of disease pathogenesis and utilization of experimental models to assist with evaluating performance of new approaches.

Altered Offspring Immunity in Maternal Parasitic Infections

Maternal infection during pregnancy is known to alter the development and function of offspring's immune system, leading to inappropriate immune responses to common childhood infections and immunizations. Although this is an expanding field, maternal parasitic infections remain understudied. Millions of women of reproductive age are currently at risk for parasitic infection, whereas many pregnant, chronically infected women are excluded from mass drug administration due partially to a lack of resources, as well as fear of unknown adverse fetal developmental outcomes. In areas endemic for multiple parasitic infections, such as sub-Saharan Africa, there are increased rates of morbidity and mortality for various infections during early childhood in comparison with nonendemic areas. Despite evidence supporting similar immunomodulatory effects between various parasite species, there is no clear mechanistic understanding of how maternal infection reprograms offspring immunity. This brief review will compare the effects of selected maternal parasitic infections on offspring immunity.

Black in Immuno Week: Who We Are, What We Did, and Why It Matters

Our organization, Black in Immuno (@BlackInImmuno), was formed in September 2020 to celebrate, support, and amplify Black voices in immunology when social media campaigns like #BlackInTheIvory illuminated the shared overt and covert issues of systemic racism faced by Black researchers in all facets of science, technology, engineering, art, and mathematics. Black in Immuno was cofounded by a group of Black immunology trainees working at multiple institutions globally: Joël Babdor, E. Evonne Jean, Elaine Kouame, Alexis S. Mobley, Justine C. Noel, and Madina Wane. We devised Black in Immuno Week, held November 22-28, 2020, as a global celebration of Black immunologists. The week was designed to advocate for increased diversity and accessibility in immunology, amplify Black excellence in immunology, and create a community of Black immunologists who can support each other to flourish despite barriers in academia and other job sectors. The week contained live panels and scientific talks, a casual networking mixer, online advocacy and amplification sessions, and a series of wellness events. Our live-streamed programs reached over 300 individuals, and thousands of people kept the conversations going globally using #BlackInImmuno and #BlackInImmunoWeek on social media from five continents. Below, we highlight the events and significant takeaways of the week.

Influence of schistosomiasis on host vaccine responses

Schistosomiasis is a debilitating helminthiasis which commonly establishes as a chronic infection in people from endemic areas. As a potent modulator of the host immune response, the Schistosoma parasite and its associated products can directly interfere with its host's ability to mount adequate immune responses to unrelated antigens. As a result, increased attention is gathering on studies assessing the influence of helminths, particularly the causal agent of schistosomiasis, on host responsiveness to vaccines. However, to date, no consensus has been drawn regarding the influence of schistosomiasis on host vaccine responses. Here, we review available evidence on the influence of transgenerational and direct Schistosoma parasite exposure on host immune responses to unrelated vaccines. In addition, we evaluate the potential of praziquantel (PZQ) treatment in restoring schistosomiasis-impacted vaccine responses.