Olfactory signaling components and olfactory receptors are expressed in tubule cells of the human kidney.

Cells of the renal tubule system are in direct contact with compounds dissolved in the urine, such as short chain fatty acids (SCFA). Murine OR78, a member of the olfactory receptor (OR) family, is involved in SCFA-related regulation of renal blood pressure in mice. It is still unclear whether OR signaling has an impact on human renal physiology. In our study, we showed that OR51E1 and OR11H7, both of which can be activated by the SCFA isovaleric acid, are expressed in the HK-2 human proximal tubule cell line. We observed a transient increase in intracellular Ca2+ when isovaleric acid and 4-methylvaleric acid were added to HK-2 cells. The isovaleric acid-induced response was dependent on extracellular Ca2+ and adenylyl cyclase (AC) activation. Furthermore, we demonstrated that the canonical olfactory signaling components Gαolf and ACIII are co-localized with OR51E1. The number of cells responding to isovaleric acid correlated with the presence of primary cilia on HK-2 cells. OR51E1 protein expression was confirmed in the tubule system of human kidney tissue. Our study is the first to show the expression of ORs and olfactory signaling components in human kidney cells. Additionally, we discuss ORs as potential modulators of the renal physiology.

Potency of different red light sources in photodynamic induction of cell death in a squamous cell carcinoma cell line.

LED illumination systems were found to be more efficacious than broad spectrum lamps in recent phase III trials on photodynamic treatment of actinic keratosis. However, a detailed comparison of the light doses emitted at the appropriate spectral range and its correlation to photodynamic effects is thus far not available for the most frequently used devices. Here, we compared the spectral emissions of three different PDT lamps with their potency of inducing cell death in ALA-loaded A431 cells, including a new system equipped with more advanced LEDs matching the photosensitizer absorption peak more precisely and emitting more homogeneous light over time. Cells were exposed to two different ALA concentrations, incubated for 1 or 3h and then illuminated by one of two different LED or a broad-spectrum system at four different light doses, whereupon viability was assessed. Maximal doses were selected in accordance to clinically applied light doses in recent phase III studies and the manufacturers' recommendations. The data gathered here clearly demonstrate that the two LED systems were significantly more effective in inducing cell death than the broad spectrum system. Most efficient was the newer LED system, in agreement with emission parameters that more accurately corresponded to the photosensitizer's absorption peak.