Association of genetic variants of PD1 with recurrent pregnancy loss

Understanding recurrent pregnancy loss: recent advances on its etiology, clinical diagnosis, and management

Recurrent pregnancy loss (RPL) has become an important reproductive health issue worldwide. RPL affects about 2%-3% of reproductive-aged women, and makes serious threats to women's physical and mental health. However, the etiology of approximately 50% of RPL cases remains unknown (unexplained RPL), which poses a big challenge for clinical management of these patients. RPL has been widely regarded as a complex disease where its etiology has been attributed to numerous factors. Heretofore, various risk factors for RPL have been identified, such as maternal ages, genetic factors, anatomical structural abnormalities, endocrine dysfunction, prethrombotic state, immunological factors, and infection. More importantly, development and applications of next generation sequencing technology have significantly expanded opportunities to discover chromosomal aberrations and single gene variants responsible for RPL, which provides new insight into its pathogenic mechanisms. Furthermore, based upon patients' diagnostic evaluation and etiologic diagnosis, specific therapeutic recommendations have been established. This review will highlight current understanding and recent advances on RPL, with a special focus on the immunological and genetic etiologies, clinical diagnosis and therapeutic management.

PD-1 mediates decidual γδ T cells cytotoxicity during recurrent pregnancy loss

PROBLEM

Recurrent pregnancy loss (RPL) is one of the big challenges of normal pregnancy. Immune dysregulation has been proposed for the key underline mechanisms of RPL. However, the essential roles of T cells, especially γδ T cells, have not been defined.

METHOD OF STUDY

Decidua were obtained from normal pregnancy women or recurrent pregnancy loss patients and the surface molecules of γδ T cells in decidua were evaluated via flow cytometric analysis. The expression of PD-1 in clinical samples was analyzed by immunohistochemistry assay. The intracellular cytokines of decidual PD-1⁺ and PD-1^- γδ T cells were evaluated by flow cytometric analysis. The cytotoxicity of PD-1^- γδ T cells were confirmed via an in vitro co-culture experiment. The specific inhibitors for Erk, p38 and JNK against the MAPK pathway were added to the co-culture media to evaluate the functions of the Erk, p38 and JNK.

RESULTS

We demonstrated that PD-1 was significantly decreased on decidual tissue γδ T cells of patients with RPL, resulting in the enhanced cytotoxicity of γδ T cells against trophoblasts. We further elucidated an Erk-dependent TNF-α production mediates the γδ T cell cytotoxicity against the trophoblast cells. Finally, the reduced expression of PD-L1 in the villi tissues of patients with RPL might be the cause of the reduction of PD-1 on the tissue γδ T cells.

CONCLUSION

Our study uncovers an important role of PD-1 expression on decidual γδ T cells in maintaining the normal pregnancy, and may provide a new strategy for immune therapy against RPL.

Next generation of immune checkpoint molecules in maternal-fetal immunity

Successful pregnancy is a unique situation requires the maternal immune system to recognize and tolerate a semi-identical fetus and allow normal invasion of trophoblast cells. Although efforts have been made, the deep mechanisms of the maternal-fetal crosstalk have not yet been fully deciphered. Immune checkpoint molecules (ICMs) are a group of negative modulators of the immune response that avoid immune damage. They have been extensively studied in the fields of oncology and transplantation, while the latest evidence suggests that they are closely associated with pregnancy outcomes via multiple inhibitory mechanisms. Although studies have mostly demonstrated the regulatory role of the well-known PD-1, CTLA-4 at the maternal-fetal interface, what is unique about the newly discovered multiple ICMs remains a mystery. Here, we review the latest knowledge on ICMs, focusing on the first generation of checkpoints (PD-1, CTLA-4) and the next generation (Tim-3, Tigit, Lag-3, VISTA) highlighting their immunoregulatory roles in maternal-fetal tolerance and decidual vascular remodeling, and their involvement in pathological pregnancies. The content covers three aspects: the characteristics they possess, the dynamic expression profile of their expression at the maternal-fetal interface, and their involvement in pathological pregnancy. In immunotherapy strategies for pregnancy complications, upregulation of immune checkpoints may play a role. Meanwhile, the impact on pregnancy outcomes when using ICMs in clinical cancer treatment during pregnancy is a topic worth exploring. These may serve as a guide for future basic research and clinical applications of maternal-fetal immunity.

Considering adjuvant therapy for stage II melanoma

Melanoma is among the few cancers that demonstrate an increasing incidence over time. Simultaneously, this trend has been marked by an epidemiologic shift to earlier stage at diagnosis. Before 2011, treatment options were limited for patients with metastatic disease, and the median overall survival was less than 1 year. Since then, the field of melanoma therapeutics has undergone major changes. The use of anti–CTLA‐4 and anti‐PD1 immune checkpoint inhibitors and combination BRAF/MEK inhibitors for patients with BRAF V600 mutations has significantly extended survival and allowed some patients to remain in durable disease remission off therapy. It has now been confirmed that these classes of agents have a benefit for patients with stage III melanoma after surgical resection, and anti‐PD1 and BRAF/MEK inhibitors are standards of care in this setting. Some patients with stage II disease (lymph node‐negative; American Joint Committee on Cancer stage IIB and IIC) have worse melanoma‐specific survival relative to some patients with stage III disease. Given these results, expanding the population of patients who are considered for adjuvant therapy to include those with stage II melanoma has become a priority, and randomized phase 3 clinical trials are underway. Moving into the future, the validation of patient risk‐stratification and treatment‐benefit prediction models will be important to improve the number needed to treat and limit exposure to toxicity in the large population of patients with early stage melanoma.

Adjuvant therapy has improved outcomes in patients with stage III melanoma and is being explored in those with stage II melanoma. Stage III data as well as risk‐stratification tools and clinical considerations for the lymph node‐negative population are reviewed.