Fetomaternal microchimerism in tissue repair and tumor development

Parkinson's Spectrum Mechanisms in Pregnancy: Exploring Hypothetical Scenarios for MSA in the Era of ART

Multiple System Atrophy (MSA) is a rare, rapidly progressive neurodegenerative disorder marked by autonomic dysfunction, parkinsonism, and cerebellar ataxia. While predominantly affecting individuals in their fifth or sixth decade, advancements in assisted reproductive technologies (ART) have created new clinical scenarios involving pregnancies in women within MSA's typical onset range. Given the scarcity of documented MSA pregnancies, this review leverages insights from related Parkinson's spectrum mechanisms to explore hypothetical scenarios for how pregnancy-induced physiological changes might influence MSA progression. Pregnancy-induced hormonal fluctuations, including elevated estrogen and progesterone levels, may modulate α-synuclein aggregation and neuroinflammatory pathways. Immune adaptations, such as fetal microchimerism and Th2-biased immune profiles, introduce additional complexities, particularly in donor embryo pregnancies involving complex microchimerism. Metabolic demands and oxidative stress further intersect with these mechanisms, potentially accelerating disease progression. We analyze existing literature and theoretical models, emphasizing the need for interdisciplinary research. Clinical implications are discussed to propose evidence-based strategies for optimizing maternal-fetal outcomes. This paper identifies critical knowledge gaps and proposes avenues for future investigation to optimize maternal-fetal outcomes in this unique and underexplored clinical intersection.

Micro-to multi-chimerism: the multiple facets of a singular phenomenon

Natural chimeras are prevalent in nature (> 10 phyla of protists, plants, invertebrates, and vertebrates), disrupting the conventional believe that genetically homogeneous entities are selected to prevent conflicts within an organism. Chimerism emerges as a significant ecological/evolutionary mechanism, shaping the life history characteristics of metazoans, and it develops in various forms, one of which is called 'microchimerism'. Furthermore, chimerism is a pivotal phenomenon, presenting complex biological and ecological expressions akin to a "double-edged sword", bypassing both innate and adaptive immune responses. Considering the proportionate contribution of chimeric partners and their spatial arrangements within chimeras, unveils six somatic states of chimerism (purged-chimerism, sectorial-chimerism, mosaic-chimerism, mixed-chimerism, microchimerism and multi-chimerism) and three states of germline chimerism (mixed-chimerism, male/female chimerism and parasitic germline chimerism). These diverse chimeric states are categorized into two distinct series of continua, namely 'somatic cell chimerism' and 'germline chimerism' scenarios where dynamic chimeric states transit into other states, and vice versa, within a specific continuum that relies on the concept of an endless 'Escherian stairwell' of chimerism states. Also, the same chimera may portray simultaneously, different chimeric states in various parts/organs. We further reviewed the evolutionary perspectives for chimerism, raising five commonly shared features of chimerism (multichimerism, ontogenic windows, reproductive chimerism, transmissible chimerism, germline hitchhiking) and 'costs' and 'benefits' accrued to chimerism, shared between invertebrates and vertebrates, including humans. We contest that 'microchimerism' lacks any quantitative definition, represents just a single facet in the multi-facet panorama of chimeric phenomena that demonstrate transitions over time into other states. All of the above carry evolutionary and clinical implications.

The duality of microchimerism and cancer in parous women: a review and evolutionary perspective

The transfer of a small number of cells between parent and offspring during pregnancy, commonly referred to as microchimerism, is thought to occur in all human pregnancies. The impact of microchimeric cells on health outcomes in mothers and offspring with respect to cancer, remains unknown. Molecular and epidemiological studies yield conflicting results on the link between microchimerism and cancer, underscoring the complexity of this phenomenon. Further, most studies on microchimerism and cancer focus on the relationship between circulating fetal cells in parous women. Given that the cellular exchange between the mother and offspring is thought to have arisen due to the evolution of internal gestation, we provide an evolutionary perspective on how internal gestation may impact the risk of cancer in humans. We highlight the potential mechanisms that may play a role in cancer vulnerability in mammals, such as genomic conflict and placental invasion. We then review the literature to investigate the effects of microchimerism on cancer outcomes in parous women, highlighting each study's interpretation of the role microchimeric cells play in cancer development, whether it is a protective or contributing role. We conclude that our current understanding of the relationship between microchimerism and cancer is poorly understood and propose mechanisms for when we would expect to see microchimerism contribute to a role in protecting the host from cancer and when microchimerism may contribute to tumor development. Future studies, including more advanced methods to detect and identify microchimerism, will be important for elucidating the link between microchimerism and cancer initiation and progression.

Maternal microchimeric cell trafficking and its biological consequences depend on the onset of inflammation at the feto-maternal interface

Microchimerism is defined as the presence of a small population of genetically distinct cells within a host that is derived from another individual. Throughout pregnancy, maternal and fetal cells are known to traffic across the feto-maternal interface and result in maternal and fetal microchimerism, respectively. However, the routes of cell transfer, the molecular signaling as well as the timing in which trafficking takes place are still not completely understood. Recently, the presence of inflammation at the feto-maternal interface has been linked with maternal microchimeric cells modulating organ development in the fetus. Here, we review the current literature and suggest that inflammatory processes at the feto-maternal interface tissues are a physiological prerequisite for the establishment of microchimerism. We further propose a spatio-temporal corridor of microchimeric cell migration to potentially explain some biological effects of microchimerism. Additionally, we elaborate on the possible consequences of a shift in this spatio-temporal corridor, potentially responsible for the development of pathologies in the neonate.

"Lazarus Response" When Feto-Maternal Microchimerism Kicks in: Spontaneous Remission in Refractory Primary Mediastinal B Cell Lymphoma Following Twin Pregnancy

Background: Spontaneous remission of cancer is a rare and poorly understood phenomenon characterized by complete or partial remission of a malignancy in the absence of or with inadequate treatment. The underlying mechanism for such occurrences is poorly understood, however, immune mechanisms seem to play an important role in such cases. In recent years increasingly more data have become available in favor of the clinical benefit of low levels of chimerism in hematologic malignancies. One such instance of naturally occurring low-level chimerism is feto-maternal microchimerism which has been shown to influence cancer progression and, in some instances, to be a protective factor against malignancy. Case report: We report a case of a young female patient with aggressive primary mediastinal large B cell lymphoma refractory to two lines of chemo-immunotherapy achieving sustained complete metabolic remission of tumor while pregnant with twins. Results: A focus on feto-maternal microchimerism during and after pregnancy revealed transient levels of feto-maternal microchimerism in the peripheral blood of the patient as measured by quantifying the Y-chromosome-linked SRY gene. Conclusions: Microchimerism presents significant potential for enhancing our comprehension of disease mechanisms, uncovering novel therapeutic targets, and refining diagnostic and treatment approaches, especially concerning cancer.

The 'communicatome' of pregnancy: spotlight on cellular and extravesicular chimerism

Communication via biological mediators between mother and fetus are key to reproductive success and offspring's future health. The repertoire of mediators coding signals between mother and fetus is broad and includes soluble factors, membrane-bound particles and immune as well as non-immune cells. Based on the emergence of technological advancements over the last years, considerable progress has been made toward deciphering the "communicatome" between fetus and mother during pregnancy and even after birth. In this context, pregnancy-associated chimerism has sparked the attention among immunologists, since chimeric cells-although low in number-are maintained in the allogeneic host (mother or fetus) for years after birth. Other non-cellular structures of chimerism, e.g. extracellular vesicles (EVs), are increasingly recognized as modulators of pregnancy outcome and offspring's health. We here discuss the origin, distribution and function of pregnancy-acquired microchimerism and chimeric EVs in mother and offspring. We also highlight the pioneering concept of maternal microchimeric cell-derived EVs in offspring. Such insights expand the understanding of pregnancy-associated health or disease risks in mother and offspring.

Enhanced fetal hematopoiesis in response to symptomatic SARS-CoV-2 infection during pregnancy

BACKGROUND

Pregnant women and their fetuses are particularly susceptible to respiratory pathogens. How they respond to SARS-CoV-2 infection is still under investigation.

METHODS

We studied the transcriptome and phenotype of umbilical cord blood cells in pregnant women infected or not with SARS-CoV-2.

RESULTS

Here we show that symptomatic maternal COVID-19 is associated with a transcriptional erythroid cell signature as compared with asymptomatic and uninfected mothers. We observe an expansion of fetal hematopoietic multipotent progenitors skewed towards erythroid differentiation that display increased clonogenicity. There was no difference in inflammatory cytokines levels in the cord blood upon maternal SARS-CoV-2 infection. Interestingly, we show an activation of hypoxia pathway in cord blood cells from symptomatic COVID-19 mothers, suggesting that maternal hypoxia may be triggering this fetal stress hematopoiesis.

CONCLUSIONS

Overall, these results show a fetal hematopoietic response to symptomatic COVID-19 in pregnant mothers in the absence of vertically transmitted SARS-CoV-2 infection which is likely to be a mechanism of fetal adaptation to the maternal infection and reduced oxygen supply.

Adaptation in the face of internal conflict: the paradox of the organism revisited

The paradox of the organism refers to the observation that organisms appear to function as coherent purposeful entities, despite the potential for within-organismal components like selfish genetic elements and cancer cells to erode them from within. While it is commonly accepted that organisms may pursue fitness maximisation and can be thought to hold particular agendas, there is a growing recognition that genes and cells do so as well. This can lead to evolutionary conflicts between an organism and the parts that reside within it. Here, we revisit the paradox of the organism. We first outline its conception and relationship to debates about adaptation in evolutionary biology. Second, we review the ways selfish elements may exploit organisms, and the extent to which this threatens organismal integrity. To this end, we introduce a novel classification scheme that distinguishes between selfish elements that seek to distort transmission versus those that seek to distort phenotypic traits. Our classification scheme also highlights how some selfish elements elude a multi-level selection decomposition using the Price equation. Third, we discuss how the organism can retain its status as the primary fitness-maximising agent in the face of selfish elements. The success of selfish elements is often constrained by their strategy and further limited by a combination of fitness alignment and enforcement mechanisms controlled by the organism. Finally, we argue for the need for quantitative measures of both internal conflicts and organismality.

Increased fetal microchimerism in immune and stem cell subsets in preeclampsia

PROBLEM

Preeclampsia (PE) is associated with an increased risk of maternal cardiovascular disease (CVD), however, it is unclear whether this is due to shared underlying physiology or changes which occur during the disease process. Fetal microchimerism (FMc) within the maternal circulation can durably persist decades after pregnancy, is known to occur at greater frequency in PE, and can potentially affect local and systemic immune programming, thus changes in cellular FMc may provide a mechanism for long-term health outcomes associated with PE.

METHOD OF STUDY

We investigated whether PE is associated with alterations in FMc immune and stem cell populations. We analyzed maternal peripheral blood mononuclear cells (PBMC) from PE cases (n = 16) and matched controls from normal pregnancies (n = 16), from which immune and stem cell subsets were isolated by flow cytometry. Genomic DNA was extracted from total PMBC and individual cell subsets, and FMc frequency was quantified by quantitative polymerase chain reaction assays targeting a fetal-specific non-shared polymorphism identified from family genotyping.

RESULTS

There was a significant increase in FMc concentration in immune cell subsets in PE cases compared to controls, predominantly in B cell, and NK cell lymphocyte populations. There was no significant difference in FMc frequency or concentration within the stem cell population between PE and controls.

CONCLUSIONS

The altered concentrations of immune cells within FMc in the maternal blood provides a potential mechanism for the inflammation which occurs during PE to induce long-lasting changes to the maternal immune system and may potentially promote chronic maternal disease.

Exploring genetic and immune underpinnings of the sexual dimorphism in tumor response to immune checkpoints inhibitors: A narrative review

Introduction

In spite of the undisputed relevance of sex as critical biologic variable of the immune landscape, still limited is our understanding of the basic mechanisms implicated in sex-biased immune response thereby conditioning the therapeutic outcome in cancer patients. This hindrance delays the actual attempts to decipher the heterogeneity of cancer and its immune surveillance, further digressing the achievement of predictive biomarkers in the current immunotherapy-driven scenario. Body: The present review concisely reports on genetic, chromosomal, hormonal, and immune features underlying sex-differences in the response to immune checkpoint inhibitors (ICIs). In addition to outline the need of robust data on ICI pharmaco-kinetics/dynamics, our survey might provide new insights on sex determinants of ICI efficacy and suggests uncovered pathways that warrant prospective investigations.

Conclusion

According to a sharable view, we propose to widely include sex among the co-variates when assessing the clinical response to ICI in cancer patients.