Toward an understanding of allogeneic conflict in pregnancy and transplantation

Unique Lessons From the Natural Progression of Rejection in Human Uterine Allografts

INTRODUCTION

Uterus transplantation (UTx) is a novel treatment for absolute uterine infertility. Acute T cell-mediated rejection (TCMR) can be monitored only through serial cervical biopsies.

METHODS

This study, the first of its kind in human transplantation, evaluated clinical, serological, and pathophysiological manifestations of allograft rejection from immunosuppression withdrawal (ISW) to graft hysterectomy (Hx).

RESULTS

Following live birth, immunosuppression was abruptly withdrawn from six living-donor UTx recipients. ISW occurred at a median of 7.4 weeks before graft Hx. Post-ISW signs of rejection included: (1) discoloration of the cervix; (2) increased uterine size compared to day of ISW; (3) serological evidence of eosinophilia and progressive development of donor-specific antibodies (DSA) or child-specific antibodies (CSA); (4) histopathological evidence of TCMR in cervical biopsies preceding the development of antibodies in serum; and (5) C4d deposition in tissue before formation of DSA or CSA in all but two recipients. At graft Hx, endometrial glands were preferentially targeted for destruction over stroma while parametrial arteries displayed variable arteritis and fibrointimal hyperplasia.

CONCLUSION

Recognition of the progression of uterine allograft rejection may be important for other human organ recipients and drive research on modulation of immunosuppression and the paradoxical relationship between adaptive cellular and humoral immunity in natural pregnancies.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02656550.

Mechanisms and consequences of sex differences in immune responses

Biological sex differences refer to differences between males and females caused by the sex chromosome complement (that is, XY or XX), reproductive tissues (that is, the presence of testes or ovaries), and concentrations of sex steroids (that is, testosterone or oestrogens and progesterone). Although these sex differences are binary for most human individuals and mice, transgender individuals receiving hormone therapy, individuals with genetic syndromes (for example, Klinefelter and Turner syndromes) and people with disorders of sexual development reflect the diversity in sex-based biology. The broad distribution of sex steroid hormone receptors across diverse cell types and the differential expression of X-linked and autosomal genes means that sex is a biological variable that can affect the function of all physiological systems, including the immune system. Sex differences in immune cell function and immune responses to foreign and self antigens affect the development and outcome of diverse diseases and immune responses.

Nested Selves: Self-Organization and Shared Markov Blankets in Prenatal Development in Humans

The immune system is a central component of organismic function in humans. This paper addresses self-organization of biological systems in relation to-and nested within-other biological systems in pregnancy. Pregnancy constitutes a fundamental state for human embodiment and a key step in the evolution and conservation of our species. While not all humans can be pregnant, our initial state of emerging and growing within another person's body is universal. Hence, the pregnant state does not concern some individuals but all individuals. Indeed, the hierarchical relationship in pregnancy reflects an even earlier autopoietic process in the embryo by which the number of individuals in a single blastoderm is dynamically determined by cell- interactions. The relationship and the interactions between the two self-organizing systems during pregnancy may play a pivotal role in understanding the nature of biological self-organization per se in humans. Specifically, we consider the role of the immune system in biological self-organization in addition to neural/brain systems that furnish us with a sense of self. We examine the complex case of pregnancy, whereby two immune systems need to negotiate the exchange of resources and information in order to maintain viable self-regulation of nested systems. We conclude with a proposal for the mechanisms-that scaffold the complex relationship between two self-organising systems in pregnancy-through the lens of the Active Inference, with a focus on shared Markov blankets.

Sex as a biological variable: Mechanistic insights and clinical relevance in solid organ transplantation

Biological sex affects immunity broadly, with recognized effects on the incidence and severity of autoimmune diseases, infections, and malignancies. Consequences of sex on alloimmunity and outcomes in solid organ transplantation are less well defined. Clinical studies have shown that donor and recipient sex independently impact transplant outcomes, which are further modified by aging. Potential mechanisms have thus far not been detailed and may include hormonal, genetic, and epigenetic components. Here, we summarize relevant findings in immunity in addition to studies in clinical and experimental organ transplantation detailing the effects of biological sex on alloimmunity. Understanding both clinical impact and mechanisms is expected to provide critical insights on the complexity of alloimmune responses, with the potential to fine-tune treatment and allocation while providing a rationale to include both sexes in transplant research.

Prospective examination of HLA sensitization after VAD implantation in children and adults

BACKGROUND

Ventricular assist devices (VADs) have improved survival to heart transplantation (HTx). However, VADs have been associated with development of antibodies against human leukocyte antigen (HLA-Ab) which may limit the donor pool and decrease survival post-HTx. Since HLA-Ab development after VAD insertion is poorly understood, the purpose of this prospective single-center study was to quantify the incidence of and evaluate risk factors for HLA-Ab development across the age spectrum following VAD implantation.

METHODS

Adult and pediatric patients undergoing VAD placement as bridge to transplant or transplant candidacy between 5/2016 and 7/2020 were enrolled. HLA-Ab were assessed pre-VAD and at 1-, 3-, and 12-months post-implant. Factors associated with HLA-Ab development post-VAD implant were explored using univariate and multivariate logistic regression.

RESULTS

15/41 (37%) adults and 7/17 (41%) children developed new HLA-Ab post-VAD. The majority of patients (19/22) developed HLA-Ab within two months of implant. New class I HLA-Ab were more common (87% adult, 86% pediatric). Prior pregnancy was strongly associated with HLA-Ab development in adults post-VAD (HR 16.7, 95% CI 1.8-158, p = 0.01). Of the patients who developed new HLA-Ab post-VAD, in 45% (10/22) the HLA-Ab resolved while in 55% (12/22) the HLA-Ab persisted.

CONCLUSION

More than one-third of adult and pediatric VAD patients developed new HLA-Ab early after VAD implant with the majority having class I antibodies. Prior pregnancy was strongly associated with post-VAD HLA-Ab development. Further studies are needed to predict regression or persistence of HLA-Ab developed post-VAD, to understand modulation of individuals' immune responses to sensitizing events, and to determine whether transiently detected HLA-Ab post-VAD recur and have long-term clinical impact post-heart transplantation.

The Molecular Mechanisms of HLA-G Regulatory Function on Immune Cells during Early Pregnancy

Human leukocyte antigen-G (HLA-G) is a non-classical human major histocompatibility complex (MHC-I) molecule with the membrane-bound and soluble types. HLA-G is primarily expressed by extravillous cytotrophoblast cells located at the maternal-fetal interface during pregnancy and is essential in establishing immune tolerance. This review provides a comprehensive understanding of the multiple molecular mechanisms by which HLA-G regulates the immune function of NK cells. It highlights that HLA-G binds to microRNA to suppress NK cell cytotoxicity and stimulate the secretion of growth factors to support fetal growth. The interactions between HLA-G and NK cells also activate senescence signaling, promoting spiral artery remodeling and maintaining the balance of maternal-fetal immune responses. In addition, HLA-G can inhibit the function of decidual T cells, dendritic cells, and macrophages. Overall, the interaction between trophoblast cells and immune cells mediated by HLA-G plays a crucial role in understanding immune regulation at the maternal-fetal interface and offers insights into potential treatments for pregnancy-related diseases.

Phase II, Open-Label Clinical Trial of Urinary-Derived Human Chorionic Gonadotropin/Epidermal Growth Factor for Life-Threatening Acute Graft-versus-Host Disease

Treatments that aid inflammation resolution, immune tolerance, and epithelial repair may improve outcomes beyond high-dose corticosteroids and other broad immunosuppressants for life-threatening acute graft-versus-host disease (aGVHD). We studied the addition of urinary-derived human chorionic gonadotropin/epidermal growth factor (uhCG/EGF; Pregnyl; Organon, Jersey City, NJ) to standard aGVHD therapy in a prospective Phase II clinical trial (ClinicalTrials.gov identifier NCT02525029). Twenty-two patients with Minnesota (MN) high-risk aGVHD received methylprednisolone 48 mg/m2/day plus 2000 units/m2 of uhCG/EGF s.c. every other day for 1 week. Patients requiring second-line aGVHD therapy received uhCG/EGF 2000 to 5000 units/m2 s.c. every other day for 2 weeks plus standard of care immunosuppression (physician's choice). Responding patients were eligible to receive maintenance doses twice weekly for 5 weeks. Immune cell subsets in peripheral blood were evaluated by mass cytometry and correlated with plasma amphiregulin (AREG) level and response to therapy. Most patients had stage 3-4 lower gastrointestinal tract GVHD (52%) and overall grade III-IV aGVHD (75%) at time of enrollment. The overall proportion of patients with a response at day 28 (primary endpoint) was 68% (57% with complete response, 11% with partial response). Nonresponders had higher baseline counts of KLRG1+ CD8 cells and T cell subsets expressing TIM-3. Plasma AREG levels remained persistently elevated in nonresponders and correlated with AREG expression on peripheral blood T cells and plasmablasts. The addition of uhCG/EGF to standard therapy is a feasible supportive care measure for patients with life-threatening aGVHD. As a commercially available, safe, and inexpensive drug, uhCG/EGF added to standard therapy may reduce morbidity and mortality from severe aGVHD and merits further study.

Construction of the systemic anticancer immune environment in tumour-bearing humanized mouse by using liposome-encapsulated anti-programmed death ligand 1 antibody-conjugated progesterone

Immune checkpoint inhibitors highlight the importance of anticancer immunity. However, their clinical utility and safety are limited by the low response rates and adverse effects. We focused on progesterone (P4), a hormone produced by the placenta during pregnancy, because it has multiple biological activities related to anticancer and immune regulation effects. P4 has a reversible immune regulatory function distinct from that of the stress hormone cortisol, which may drive irreversible immune suppression that promotes T cell exhaustion and apoptosis in patients with cancer. Because the anticancer effect of P4 is induced at higher than physiological concentrations, we aimed to develop a new anticancer drug by encapsulating P4 in liposomes. In this study, we prepared liposome-encapsulated anti-programmed death ligand 1 (PD-L1) antibody-conjugated P4 (Lipo-anti-PD-L1-P4) and evaluated the effects on the growth of MDA-MB-231 cells, a PD-L1-expressing triple-negative breast cancer cell line, in vitro and in NOG-hIL-4-Tg mice transplanted with human peripheral blood mononuclear cells (humanized mice). Lipo-anti-PD-L1-P4 at physiological concentrations reduced T cell exhaustion and proliferation of MDA-MB-231 in vitro. Humanized mice bearing MDA-MB-231 cells expressing PD-L1 showed suppressed tumor growth and peripheral tissue inflammation. The proportion of B cells and CD4+ T cells decreased, whereas the proportion of CD8+ T cells increased in Lipo-anti-PD-L1-P4-administrated mice spleens and tumor-infiltrated lymphocytes. Our results suggested that Lipo-anti-PD-L1-P4 establishes a systemic anticancer immune environment with minimal toxicity. Thus, the use of P4 as an anticancer drug may represent a new strategy for cancer treatment.