Infertile men have few treatment options. Here, we demonstrate that the transmembrane receptor activator of NF-kB ligand (RANKL) signaling system is active in mouse and human testis. RANKL is highly expressed in Sertoli cells and signals through RANK, expressed in most germ cells, whereas the RANKL-inhibitor osteoprotegerin (OPG) is expressed in germ and peritubular cells. OPG treatment increases wild-type mouse sperm counts, and mice with global or Sertoli-specific genetic suppression of Rankl have increased male fertility and sperm counts. Moreover, RANKL levels in seminal fluid are high and distinguishes normal from infertile men with higher specificity than total sperm count. In infertile men, one dose of Denosumab decreases RANKL seminal fluid concentration and increases serum Inhibin-B and anti-Müllerian-hormone levels, but semen quality only in a subgroup. This translational study suggests that RANKL is a regulator of male reproductive function, however, predictive biomarkers for treatment-outcome requires further investigation in placebo-controlled studies.

Vitamin D is important for gonadal function in rodents, and improvement of vitamin D status in men with low sperm counts increases live birth rate. Vitamin D is a regulator of transcellular calcium transport in the intestine and kidney and may influence the dramatic changes in the luminal calcium concentration in epididymis. Here, we show spatial expression in the male reproductive tract of vitamin D receptor (VDR)-regulated factors involved in calcium transport: transient receptor potential vanilloid 5/6 , sodium/calcium exchanger 1, plasma membrane calcium ATPase 1, calbindin D_9k, calcium-sensing receptor (CaSR), and parathyroid hormone-related peptide (PTHrP) in mouse and human testis and epididymis. Testicular Casr expression was lower in Vdr ablated mice compared with controls. Moreover, expression levels of Casr and Pthrp were strongly correlated in both testis and epididymis and Pthrp was suppressed by 1,25(OH)₂D₃ in a spermatogonial cell line. The expression of CaSR in epididymis may be of greater importance than in the gonad in mice as germ cell-specific Casr deficient mice had no major reproductive phenotype, and coincubation with a CaSR-agonist had no effect on human sperm–oocyte binding. In humans, seminal calcium concentration between 5 and 10 mM was associated with a higher fraction of motile and morphologically normal sperm cells, and the seminal calcium concentration was not associated with serum calcium levels. In conclusion, VDR regulates CaSR and PTHrP, and both factors may be involved in the regulation of calcium transport in the male reproductive tract with possible implications for sperm function and storage.

Intramuscular Injections of paraffin oil can cause foreign body granuloma formation and hypercalcemia. Macrophages with the ability to produce high levels of 1,25(OH)₂D₃ may induce the mineral disturbance but no major series of patients have been published to date. Here, medical history, physical evaluation, biochemical and urinary analysis for calcium homeostasis were obtained from 88 males, who 6 years previously had injected paraffin or synthol oil into skeletal muscle. Moreover, granuloma tissue from three men was cultured for 48 hours ex vivo to determine 1,25(OH)₂D₃‐production supported by qPCR and immunohistochemistry of vitamin D metabolism and immune cell populations following treatment with 14 different drugs. The 88 men were stratified into men with hypercalcemia (34%), while normocalcemic men were separated into men with either normal (42%) or suppressed parathyroid hormone (PTH) (24%). All men had high calcium excretion and nephrolithiasis was found in 48% of hypercalcemic men, 22% of normocalcemic men with normal PTH and 47% of normocalcemic men with suppressed PTH. Risk factors for developing hypercalcemia were oil volume injected, injection of heated oil, high serum interleukin‐2 receptor levels and high urine calcium. High 1,25(OH)₂D₃/25OHD ratio, calcium excretion and low PTH was associated with nephrolithiasis. The vitamin D activating enzyme CYP27B1 was markedly expressed in granuloma tissue and 1,25(OH)₂D₃ was released in concentrations corresponding to 40–50% of the production by human kidney specimens. Dexamethasone, Ketoconazole and Ciclosporin significantly suppressed granulomatous production of 1,25(OH)₂D₃. In conclusion, this study shows that injection of large oil volumes alters calcium homeostasis and increases the risk of nephrolithiasis. Hypercalciuria is an early sign of disease, and high granulomatous 1,25(OH)₂D₃ production is part of the cause. Prospective clinical trials are needed to determine if Ciclosporin, Ketoconazole or other drugs can be used as prednisolone sparing treatment.

Granuloma formation following self-administered cosmetic oil injections can lead to severe hypercalcemia and renal calcifications due to extra-renal vitamin D activation. This translational study aims to identify Prednisolone sparing therapeutics for hypercalcemia after development of granulomatous disease secondary to paraffin oil injections. Granuloma tissue isolated from five men were cultured ex vivo and treated with selected drugs to block generation of activated vitamin D (1,25(OH)₂D₃). In a retrospective study, we included data before and during different treatments of 21 men with paraffin oil induced granulomatous hypercalcemia (46 treatment courses) where serum calcium, parathyroid hormone, vitamin D metabolites, creatinine and inflammatory markers were measured. Addition of Ketoconazole or Ciclosporin to granuloma tissue ex vivo culture, significantly suppressed production of 1,25(OH)₂D₃ after 48 h (both p < 0.05). Prednisolone was the first treatment option in most men and lowered serum levels of ionized calcium after 1, 2, 3 and 6 months compared with baseline (p < 0.05). Ketoconazole or Hydroxychloroquine had no significant effect on serum calcium levels and were unable to reduce the concomitant daily Prednisolone doses (p > 0.05). Azathioprine did not reduce calcium levels. However, addition of Tacrolimus to Prednisolone treatment enabled a reduction in Prednisolone dose after 3 months (p = 0.014), but with no additional effect on calcium homeostasis. This study verifies that Prednisolone is an effective treatment and suggests that calcineurin inhibitors may be used as Prednisolone sparing treatment for paraffin oil-induced granulomatous hypercalcemia. Randomized clinical trials are needed to determine clinical efficacy.

Luteinizing hormone/choriogonadotropin receptor (LHCGR) regulates gonadal testosterone production and recent studies have suggested a growth-regulatory role in somatic cancers. Here, we established that LHCGR is expressed in a fraction of seminoma cells and germ cell neoplasia in situ (GCNIS), and the seminoma-derived cell line TCam2 released LHCGR into the medium. LH treatment induced proliferation of TCam2 cells in vitro, while hCG treatment induced a non-significant 51% increase in volume of tumors formed in a TCam2 xenograft model. A specific ELISA was used to detect a soluble LHCGR in serum. Serum concentrations of soluble LHCGR could not distinguish 4 patients with GCNIS and 216 patients with testicular germ cell tumors (TGCTs) from 297 infertile or 148 healthy young men. Instead, serum LHCGR levels were significantly higher in 112 patients with a seminoma >5 cm or elevated serum lactate dehydrogenase (LDH) compared with men harboring smaller seminomas <2 cm or normal LDH levels. Serum LHCGR levels in TGCT patients could not predict relapse irrespective whether determined pre- or post-orchiectomy. Combined, these novel findings suggest that LHCGR may be directly involved in the progression and growth of seminomas, and our retrospective pilot study suggests that serum LHCGR may have some prognostic value in men with seminoma.