Graft-Versus-Host Disease Targets Ovary and Causes Infertility After Allogeneic Hematopoietic Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative therapy for various hematologic malignancies. Infertility associated with ovarian failure is a serious late complication for female survivors of allo-HSCT. While the role of pretransplant conditioning regimen has been well appreciated, it remains to be elucidated whether GVHD could be causally related to female infertility. We have addressed this issue in a mouse model of non-irradiated bone marrow transplantation (BMT) to avoid devastating effects of irradiation on the ovary.

Female B6D2F1 (H-2^b/d) mice (10 week old) were injected with 80 × 10⁶ splenocytes from allogeneic B6 (H-2^b) or syngeneic B6D2F1 donors on day 0. To track migration of donor T cells, CAG-EGFP B6 mice were utilized. Morphometric and immunohistochemical assessments were performed on ovarian sections harvested from recipients on day +21 to evaluate the integrity of ovarian architecture and inflammatory changes. To examine ovary functions, recipients were injected with pregnant mare’s serum gonadotropin (PMSG) on day +19 and human chorionic gonadotropin (hCG) on day +21 to induce ovulation and then oocytes were collected. To evaluate fertility of the recipients, recipients were mated with B6D2F1 males after BMT and mating was repeated 6 times until day +150, and newborns were enumerated.

In this model, GVHD occurred early after BMT at a peak around day +21 particularly in the gut and liver. Histological examination of the ovaries from allogeneic recipients on day +21 demonstrated GFP⁺ donor T cells infiltrating in the layer of granulosa cells of mature follicles beyond the basement membrane, cleaved-caspase 3⁺ apoptotic granulose cells surrounded by lymphocytes (satellitosis), and the destruction of PAS⁺ basal membrane, whereas there was neither donor T cell infiltration nor pathological changes of the ovaries in syngeneic animals (p = 0.002, Table). Majority of T cells infiltrating in the ovary was CD8⁺ T cells. In experiments of forced ovulation, numbers of oocytes were significantly less in allogeneic animals than in syngeneic animals (p = 0.043, Table), indicating an impairment of ovary functions. When allogeneic recipients were mated to healthy male mice, numbers of both delivery and newborns per litter decreased, whereas syngeneic recipients remain to be fully fertile. As a result, total numbers of newborns delivered by day +150 after BMT were significantly less in allogeneic animals than in syngeneic animals (p< 0.001, Table). Administration of 10 mg/kg of prednisolone from day 0 to day +20 significantly reduced ovarian GVHD and restored numbers of oocytes in allogeneic animals to the levels of syngeneic animals.

Our results demonstrate for the first time that GVHD targets ovary and induces impairment of ovary functions and infertility; and therefore, control of GVHD as well as protection of the ovary from the conditioning is important to prevent female fertility after allo-HSCT.

No relevant conflicts of interest to declare.