Psoriasis and Altered Calcium Metabolism: Downregulated Capacitative Calcium Influx and Defective Calcium-Mediated Cell Signaling in Cultured Psoriatic Keratinocytes1  Seija-Liisa Karvonen, Timo Korkiamäki, Heli Ylä-Outinen, Marja Nissinen, Harri Teerikangas, Kati Pummi, Jaakko Karvonen, Juha Peltonen  Journal of Investigative Dermatology  Volume 114, Issue 4, Pages 693-700 (April 2000) DOI: 10.1046/j.1523-1747.2000.00926.x Copyright © 2000 The Society for Investigative Dermatology, Inc Terms and Conditions

Figure 1 Changes of [Ca2+]i in response to thapsigargin or mechanical wounding differ in psoriatic keratinocytes versus controls. All the images were acquired by real time at 340nm and 380nm wavelengths with the interval of 5s. (a) Control cells. Basal [Ca2+]i was initially 50–55nM. [Ca2+]i stores were mobilized with thapsigargin (after 10 frames from the beginning). Elevation in [Ca2+]i was approximately 107nM in control cells, and the calcium levels remained high after adding thapsigargin. (b) Psoriatic keratinocytes. Basal [Ca2+]i was initially 25–30nM. Elevation in [Ca2+]i was approximately 52nM (c) [Ca2+]i waves in control and psoriatic keratinocytes. [Ca2+]i transiently increases in cells near the wound. The rise in [Ca2+]i is significantly reduced in psoriatic keratinocytes compared with control cells. Basal [Ca2+]i was initially 50–55nM in control keratinocytes and 20–25nM in psoriatic cells, and within seconds after wounding [Ca2+]i elevated to 220nM in control cells and to 90nM in psoriatic keratinocytes in high [Ca2+]e. The [Ca2+]i elevation propagated to neighboring cells up to 15–20 cells away from the wound. The pseudocolor scale bar represents the estimated [Ca2+]i (display is calibrated as [Ca2+]i, in nM). Journal of Investigative Dermatology 2000 114, 693-700DOI: (10.1046/j.1523-1747.2000.00926.x) Copyright © 2000 The Society for Investigative Dermatology, Inc Terms and Conditions

Figure 2 Blocking of gap-junctional and P2-purinergic signaling reveals that different routes of calcium mediated signaling are dominant in psoriatic versus control keratinocytes. The total number of ratio images was 80 in capacitative calcium influx experiments and 20 or 40 in [Ca2+]i-mediated cell signaling experiments. Eight representative cells corresponding the mean peaks of [Ca2+]i were selected for the figures. In all experiments the mean increase in [Ca2+]i was analyzed from 20 to 25 cells. Parts (a)–(d) show responses in [Ca2+]i of healthy control cells and lesional psoriatic keratinocytes. (a) Elevation of [Ca2+]i in control keratinocytes and psoriatic cells. [Ca2+]i stores were depleted with thapsigargin in high [Ca2+]e. Capacitative calcium influx is downregulated in psoriatic keratinocytes. (b) Wound-induced [Ca2+]i transient in keratinocytes without blocking agents. [Ca2+]i rose significantly more in control cells than in psoriatic keratinocytes in the presence of high [Ca2+]e. (c) Wound induced [Ca2+]i transient in heptanol blocked keratinocytes. In high [Ca2+]e control cells were blocked to one-half of the response to wounding (p <0.0005), whereas psoriatic keratinocytes gave a rise similar to that on wounding, indicating their gap-junctional signaling to be almost totally defective. (d) Wound induced [Ca2+]i transient in suramin blocked keratinocytes. In high [Ca2+]e blocking of P2-purinergic receptors with suramin inhibited the rise of [Ca2+]i in psoriatic keratinocytes (p <0.0005) in contrast to control keratinocytes, which gave roughly similar responses compared with wound without blocking agents. Journal of Investigative Dermatology 2000 114, 693-700DOI: (10.1046/j.1523-1747.2000.00926.x) Copyright © 2000 The Society for Investigative Dermatology, Inc Terms and Conditions

Figure 3 The mean elevation of [Ca2+]i in psoriatic and control keratinocytes in different [Ca2+]e concentrations. (a) To study [Ca2+]i stores, Ca2+ was depleted with thapsigargin. Psoriatic keratinocytes had [Ca2+]i stores comparable to those of healthy cells, but capacitative calcium influx is clearly defective as seen in low (<0.1mM) and high (1.8mM) [Ca2+]e. (b) Wounding of the monolayer resulted in a significantly reduced response in [Ca2+]i of psoriatic keratinocytes; lesional cells were even more disturbed than nonlesional cells. (c) Blocking of gap-junctions with heptanol in wounded monolayer did not affect significantly in wounding response in psoriatic keratinocytes, whereas control cells were significantly blocked (p <0.0005). (d) On the contrary, blocking of P2-purinergic receptors with suramin resulted in significantly reduced response in psoriatic keratinocytes, and lesional cells were again more disturbed. Journal of Investigative Dermatology 2000 114, 693-700DOI: (10.1046/j.1523-1747.2000.00926.x) Copyright © 2000 The Society for Investigative Dermatology, Inc Terms and Conditions

Figure 4 Psoriatic keratinocytes are more sensitive to P2-purinergic stimulation than control keratinocytes. Addition of 100μM ATP to culture medium resulted in a slightly lower response in control (a) than in psoriatic (b) keratinocytes. Journal of Investigative Dermatology 2000 114, 693-700DOI: (10.1046/j.1523-1747.2000.00926.x) Copyright © 2000 The Society for Investigative Dermatology, Inc Terms and Conditions