In vitro morphology, viability and cytokine secretion of uterine telocyte‐activated mouse peritoneal macrophages

Abstract

Telocytes (TCs), a distinct interstitial cell population, have been identified in the uterus, oviduct and placenta, with multiple proposed potential biological functions. Their unique structure allows them to form intercellular junctions with various immunocytes, both in normal and diseased tissues, suggesting a potential functional relationship with the local immune response. It has been hypothesized that through direct heterocellular junctions or indirect paracrine effects, TCs influence the activity of local immunocytes that are involved in the inflammatory process and in immune‐mediated reproductive abnormalities. However, no reliable cytological evidence for this hypothesis is currently available. In this study, we cultured primary murine uterine TCs and collected TC conditioned media (TCM). Mouse peritoneal macrophages (pMACs) were co‐cultured for 48 hrs with TCM or with DMEM/F12 or lipopolysaccharide (LPS) as negative and positive controls, respectively. Normal uterine TCs with a typical structure and a CD‐34‐positive/vimentin‐positive/c‐kit‐negative immunophenotype were observed during culture. Morphologically, TCM‐treated pMACs displayed an obvious activation/immunoresponse, in contrast to over‐stimulation and cell death after LPS treatment and no sign of activation in the presence of DMEM/F12. Accordingly, a cell counting kit 8 (CCK‐8) assay indicated significant activation of pMACs by TCM and LPS compared to DMEM/F12, thus supporting the marked morphological differences among these groups of cells. Furthermore, within a panel of macrophage‐derived cytokines/enzymes, interleukin‐6 (IL‐6) and inducible nitric oxide synthase were significantly elevated in TCM‐treated pMACs; tumour necrosis factor α, IL1‐R1, and IL‐10 were slightly, but significantly, up‐regulated; and no changes were observed for transforming growth factor‐β1, IL‐1β, IL‐23α and IL‐18. Our results indicate that TCs are not simply innocent bystanders but are rather functional players in the activation of pMACs; they trigger and maintain the immune response, likely through indirect paracrine effects. Thus, we provide preliminary in vitro evidence of immunoregulatory and immunosurveillance roles for TCs.

Telocytes play a key role in prostate tissue organisation during the gland morphogenesis

“…The interalveolar region contained predominantly CD34‐positive cells on P30, with the formation of networks that separate the clusters of alveoli from each other and separate clusters of alveoli from the periurethral smooth muscle, thus attributing to the exclusively CD34‐positive interstitial cells uniquely a role of ICCs progenitor cells is a limited proposition, in view of the evidence that these cells possess many other functions in the tissue organisation and functionality in various organs 8, 10, 11, 12, 17, 18, 24, 25. CD34‐positive telocytes that do not express c‐Kit may also perform a pacemaker function 48, 49 via c‐Kit‐independent pathways, such as the SK3 pathway, by inhibiting electrical activity.…”

“…Telocytes may also exercise pacemaker function by means of the c‐Kit, but may also possess a supportive function for the contraction of periductal smooth muscle, possibly by means of c‐kit‐independent pathways, such as via the SK3 (small conductance calcium‐activated potassium Channel 3) pathway 20, 23. The function of telocytes varies between organs 8, 10, 11, 12, 17, 18, 24, 25, and their role in the prostate remains elusive, in addition to lack of information regarding the development of these cells in prostate tissue.…”

Telocytes in female reproductive system (human and animal)

“…Growth factors, including IL-6, VEGF, macrophage inflammatory protein 1a, macrophage inflammatory protein-2 and monocyte chemoattractant protein 1, are significantly expressed along with additional cytokines, including IL-2, IL-10, IL-13 and chemokines, such as growthrelated oncogene/keratinocyte-derived chemokine in the secretome of cultured rodent cardiac TCs [17]. Besides, in a renal ischaemia-inflammatory injury model, TCs activated the nuclear factor kappa B signalling pathway and upregulated the mRNA levels of pro-inflammatory cytokines such as IL-1 and tumour necrosis factor-a [17,18]. 1 Nanocontacts-heterocellular communications between TCs and cardiomyocytes, which do not belong to classic types of junctions found in textbooks.…”

Expression of toll‐like receptors and their regulatory roles in murine cardiac telocytes

“…Presumably, this support might contribute to tissue homeostasis, regeneration or repair and transmission of intercellular signals . Ultrastructural evidence showed that telocytes were spatially close not only to capillaries, nerve fibres, myocytes, smooth muscle cells and stem cells but also to macrophages, mast cells, eosinophils and lymphocytes . Telocytes might modulate the immunocytes through direct synapse‐like contact or indirect paracrine communication by secreting soluble mediators, such as IL‐6, VEGF and nitric oxide .…”