Consequences of depleted SERCA2-gated calcium stores in the skin.

Sarco(endo)plasmic reticulum Ca2+-ATPase isoform 2 (SERCA2) pumps belong to the family of Ca2+-ATPases responsible for the maintenance of calcium in the endoplasmic reticulum. In epidermal keratinocytes, SERCA2-controlled calcium stores are involved in cell cycle exit and onset of terminal differentiation. Hence, their dysfunction was thought to provoke impaired keratinocyte cohesion and hampered terminal differentiation. Here, we assessed cultured keratinocytes and skin biopsies from a canine family with an inherited skin blistering disorder. Cells from lesional and phenotypically normal areas of one of these dogs revealed affected calcium homeostasis due to depleted SERCA2-gated stores. In phenotypically normal patient cells, this defect compromised upregulation of p21(WAF1) and delayed the exit from the cell cycle. Despite this abnormality it failed to impede the terminal differentiation process in the long term but instead coincided with enhanced apoptosis and appearance of chronic wounds, suggestive of secondary mutations. Collectively, these findings provide the first survey on phenotypic consequences of depleted SERCA-gated stores for epidermal homeostasis that explain how depleted SERCA2 calcium stores provoke focal lesions rather than generalized dermatoses, a phenotype highly reminiscent of the human genodermatosis Darier disease.

Sputum induction and bronchoscopy for assessment of ozone-induced airway inflammation in asthma.

BACKGROUND: Neutrophilic airway inflammation, as defined by cell counts in respiratory tract lining fluid (RTLF), is a key end point in many studies of respiratory toxicity in both healthy and asthmatic subjects. BAL and sputum induction (SI) are the most common methods of sampling RTLF in such studies. However, the comparability of these methods (BAL and SI) after experimental treatment has not been investigated in a head-to-head controlled trial. METHODS: To determine whether BAL and SI are comparable and can be used in place of each other in the assessment of neutrophilic airway inflammation after ozone (O(3)) exposure, we exposed 13 asthmatic subjects to either 0.2 ppm of O(3) or filtered air (FA) followed by either BAL or SI. Subjects then underwent the alternate (O(3) or FA) exposure followed by the same method of RTLF sampling. Next, subjects repeated the same exposure protocol with the alternate method of RTLF sampling. Differences in inflammatory indexes including the percentage of polymorphonuclear neutrophils (%PMNs) between the exposures were then correlated by regression analysis. RESULTS: The %PMNs in sputum was poorly correlated with that in BAL fluid (R = 0.12). The correlation between the %PMNs in sputum and in the bronchial fraction of BAL (BFx) fluid, however, was somewhat higher (R = 0.50). Furthermore, the uncertainty of the estimate of %PMN values in BFx fluid and BAL fluid based on those of sputum values, using regression models, was almost as great as the magnitude of the O(3) effect itself (ie, 9.7% and 5.5% estimate errors for O(3) effects of 17.0% and 7.5%, respectively). CONCLUSION: We concluded that SI and BAL indexes are not directly interchangeable in the assessment of O(3)-induced airway inflammation in asthmatic subjects.