Exploring the Ion Channel TRPV2 and Testicular Macrophages in Mouse Testis

The cation channel TRPV2 is known to be expressed by murine macrophages and is crucially involved in their functionality. Macrophages are frequent cells of the mouse testis, an immune-privileged and steroid-producing organ. TRPV2 expression by testicular macrophages and possible changes associated with age or inflammation have not been investigated yet. Therefore, we studied testes of young adult and old wild-type (WT) and AROM+ mice, i.e., transgenic mice overexpressing aromatase. In these animals, inflammatory changes are described in the testis, involving active macrophages, which increase with age. This is associated with impaired spermatogenesis and therefore AROM+ mice are a model for male infertility associated with sterile inflammation. In WT animals, testicular TRPV2 expression was mapped to interstitial CD206+ and peritubular MHC II+ macrophages, with higher levels in CD206+ cells. Expression levels of TRPV2 and most macrophage markers did not increase significantly in old mice, with the exception of CD206. As the number of TRPV2+ testicular macrophages was relatively small, their possible involvement in testicular functions and in aging in WT mice remains to be further studied. In AROM+ testis, TRPV2 was readily detected and levels increased significantly with age, together with macrophage markers and TNF-α. TRPV2 co-localized with F4/80 in macrophages and further studies showed that TRPV2 is mainly expressed by unusual CD206+MHC II+ macrophages, arising in the testis of these animals. Rescue experiments (aromatase inhibitor treatment and crossing with ERαKO mice) restored the testicular phenotype and also abolished the elevated expression of TRPV2, macrophage and inflammation markers. This suggests that TRPV2+ macrophages of the testis are part of an inflammatory cascade initiated by an altered sex hormone balance in AROM+ mice. The changes in testis are distinct from the described alterations in other organs of AROM+, such as prostate and spleen. When we monitored TRPV2 levels in another immune-privileged organ, namely the brain, we found that levels of TRPV2 were not elevated in AROM+ and remained stable during aging. In the adrenal, which similar to the testis produces steroids, we found slight, albeit not significant increases in TRPV2 in both AROM+ and WT mice, which were associated with age. Thus, the changes in the testis are specific for this organ.

Effect of the exosome-mediated suppression of the estrogen signaling: the role in the progression of the hormonal resistance of breast cancer cells

The most effective treatment of the hormone-dependent breast cancer is based on the antiestrogens SERM and aromatase inhibitor treatment, however its efficiency is limited by the acquired resistance to the drugs.Previously we have revealed the effect of the transferring of the hormonal resistance from the resistant to the sensitive cells under in vitro cell co-cultivation, and demonstrated exosomes involvement in this process. Here we have shown that the exosomes of the resistant cells caused the marked inhibition of the estrogen signaling in the recipient cells, and identified microRNAs – ERα suppressors that overexpressed in the resistant exosomes.Taken together, the results obtained demonstrate the important role of the estrogen signaling suppression in the exosome-induced transferring of the hormonal resistance, and revealed the involvement of the exosomal microRNA in the ERα down-regulation.

Challenges in Preventing Bone Loss Induced by Aromatase Inhibitors

Context: Aromatase inhibitors have become a mainstay in the adjuvant treatment regimen in postmenopausal women with hormone receptor–positive breast cancer. While many of these patients have an excellent long-term prognosis, adverse effects on bone represent an emerging complication of aromatase inhibitor treatment, resulting in substantial bone loss and fragility fractures. Treatment approaches to prevent aromatase inhibitor–induced bone loss typically consist of an antiresorptive approach with bisphosphonates or the RANKL antibody denosumab. However, different guidelines vary with respect to treatment thresholds, duration, and dosing. The choice of antiresorptive regime is further complicated by comorbidities and potential disease-modifying effects of individual agents. Objective: This review summarizes the evidence of how aromatase inhibitors affect bone health and provides an update of clinical approaches to preserve bone strength in affected women. (J Clin Endocrinol Metab XX: 0–0, 2020)