Complete Kisspeptin Receptor Inactivation Does Not Impede Exogenous GnRH-Induced LH Surge in Humans.

Context: Mutations in the kisspeptin receptor (KISS1R) gene have been reported in a few patients with normosmic congenital hypogonadotropic hypogonadism (nCHH) (OMIM #146110). Objectives: To describe a female patient with nCHH and a novel homozygous KISS1R mutation and to assess the role of kisspeptin pathway to induce an ovulation by GnRH pulse therapy. Design, Setting, and Intervention: Observational study of a patient including genetic and kisspeptin receptor functions and treatment efficiency using a GnRH pump. Main Outcome Measure: Response to pulsatile GnRH therapy. Results: A partial isolated gonadotropic deficiency was diagnosed in a 28-year-old woman with primary amenorrhea and no breast development. A novel homozygous c.953T>C variant was identified in KISS1R. This mutation led to substitution of leucine 318 for proline (p.Leu318Pro) in the seventh transmembrane domain of KISS1R. Signaling via the mutated receptor was profoundly impaired in HEK293-transfected cells. The mutated receptor was not detected on the membrane of HEK293-transfected cells. After several pulsatile GnRH therapy cycles, an LH surge with ovulation and pregnancy was obtained. Conclusion: GnRH pulsatile therapy can induce an LH surge in a woman with a mutated KISS1R, which was previously thought to be completely inactivated in vivo.

GPR54 deficiency reduces the Treg population and aggravates experimental autoimmune encephalomyelitis in mice.

GPR54 is highly expressed in the central nervous system and plays a crucial role in pubertal development. However, GRP54 is also expressed in the immune system, implying possible immunoregulatory functions. Here we investigated the role of GPR54 in T cell and immune tolerance. GPR54 deficiency led to an enlarged thymus, an increased number of thymocytes, and altered thymic micro-architecture starting around puberty, indicating GPR54 function in T-cell development through its regulatory effect on the gonadal system. However, flow cytometry revealed a significant reduction in the peripheral regulatory T cell population and a moderate decrease in CD4 single-positive thymocytes in prepubertal Gpr54-/- mice. These phenotypes were confirmed in chimeric mice with GPR54 deficient bone marrow-derived cells. In addition, we found elevated T cell activation in peripheral and thymic T cells in Gpr54-/- mice. When intact mice were immunized with myelin oligodendrocyte glycoprotein, a more severe experimental autoimmune encephalomyelitis (EAE) developed in the Gpr54-/- mice. Interestingly, aggravated EAE disease was also manifested in castrated and bone marrow chimeric Gpr54-/- mice compared to the respective wild-type control, suggesting a defect in self-tolerance resulting from GPR54 deletion through a mechanism that bypassed sex hormones. These findings demonstrate a novel role for GPR54 in regulating self-tolerant immunity in a sex hormone independent manner.

A synthetic kisspeptin analog that triggers ovulation and advances puberty.

The neuropeptide kisspeptin and its receptor, KiSS1R, govern the reproductive timeline of mammals by triggering puberty onset and promoting ovulation by stimulating gonadotrophin-releasing hormone (GnRH) secretion. To overcome the drawback of kisspeptin short half-life we designed kisspeptin analogs combining original modifications, triazole peptidomimetic and albumin binding motif, to reduce proteolytic degradation and to slow down renal clearance, respectively. These analogs showed improved in vitro potency and dramatically enhanced pharmacodynamics. When injected intramuscularly into ewes (15 nmol/ewe) primed with a progestogen, the best analog (compound 6, C6) induced synchronized ovulations in both breeding and non-breeding seasons. Ovulations were fertile as demonstrated by the delivery of lambs at term. C6 was also fully active in both female and male mice but was completely inactive in KiSS1R KO mice. Electrophysiological recordings of GnRH neurons from brain slices of GnRH-GFP mice indicated that C6 exerted a direct excitatory action on GnRH neurons. Finally, in prepubertal female mice daily injections (0.3 nmol/mouse) for five days significantly advanced puberty. C6 ability to trigger ovulation and advance puberty demonstrates that kisspeptin analogs may find application in the management of livestock reproduction and opens new possibilities for the treatment of reproductive disorders in humans.