Abstract
Purpose :
Meibomian glands (MG) are specialised sebaceous glands (SG) that produce the lipid component of the tear film as part of a holocrine secretion mechanism. A disturbance of this meibum secretion leads to meibomian gland dysfunction (MGD). Prolactin (PRL), a multifunctional pituitary gland hormone regulates, among other things, cell growth and lipid release in SGs. SGs and MGs show many parallels in their function and regulation. The PRL serum level correlate negatively with tear film quality, and PRL and the prolactin receptor (PRLR) are present in the human MG. To better understand possible pathomechanisms in the MGs, the present study investigates the influence of PRL in a human meibomian gland epithelium cell line (hMGEC).
Methods :
Gene expression of PRL and PRLR was analyzed by RT-PCR in differentiated and undifferantiated hMGECs. Immunofluorescence analyses of hMGECs were conducted to verify the expression and localization of the analyzed proteins at the protein level. After stimulation with PRL (10 to 1000 ng/mL) for 24h and 48h, cell proliferation was invesitgated with a luminescent cell viability assay and lipid production was analyzed by Oil Red O staining and quantified with ImageJ.
Results :
Immunofluorescence and RT-PCR revealed the expression of PRL and PRLR in both differentiated and undifferentiated hMGECs. Undifferentiated hMGECs showed a significantly increased cell viability after 24h of stimulation with PRL in all concentrations, whereas differentiated hMGECs showed constant cell viability under the same conditions. After 48h of stimulation with 1000 ng/mL PRL, differentiated hMGECs even showed a lower cell viability than the control or the cells stimulated with less PRL. The lipid production of differentiated hMGECs was significantly higher after stimulation with PRL. Lipid production of undifferentiated hMGECs was not affected.
Conclusions :
These findings show that PRL and PRLR are expressed by undifferentiated and differentiated hMGECs. PRL significantly influences the proliferation of undifferentiated hMGECs and the lipid production of differentiated hMGECs. Changes in PRL levels appear to influence the function of MGs. Further functional analyses, in particular the examination of human tear fluid and meibum samples, are underway to demonstrate the effects of PRL in context of MGD in vivo.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.