Lactate dehydrogenase and caspase activity in nasopharyngeal secretions are predictors of bronchiolitis severity

Mehta, Reena; Scheffler, Margaret; Tapia, Lorena; Aideyan, Letisha; Patel, Kirtida D; Jewell, Alan M; Avadhanula, Vasanthi; Mei, Minghua; Garofalo, Roberto P; Piedra, Pedro A

As previously mentioned, our earlier studies demonstrated an inverse relationship between NW-LDH and bronchiolitis disease severity with children in the top quartile having a significantly lower risk of being hospitalized for bronchiolitis. 13, 14 In this study, the univariate analysis appears to contradict those previous reports. However, this report included a group of children who were older, healthier at baseline, presenting with more varied degree of illness, and had a greater proportion requiring a high level of care. Also, our samples were processed after only one freeze-thaw cycle; samples used for the earlier study underwent multiple freeze-thaw cycles, which may have adversely affected stability of the LDH isoenzymes and or quality of the samples. In our current study, we ensured the quality of our samples by providing feedback in real time on the detection of sIgA in the nasal wash fluid and using nasal wash samples thawed only once for determining LDH and caspase 3/7 activity. Also, in our previous reports, data on NW-LDH/ NW-caspase 3/7 ratio was not performed, which we believe helps to explain the dominant cellular pathway (necrosis versus apoptosis) from which LDH derives in respiratory tract fluid. As previously stated, our multiple linear models showed the same inverse relationship between NW-LDH (or NW-LDH/NW-caspase 3/7 ratio) and the severity of bronchiolitis for the children who were admitted to ACU compared with those sent home when taking into account the age of the patients. Overall, our observations over time support the concept that biomarkers such as NW-LDH and NW-caspase 3/7 reflect a complex pathway for control of respiratory viral infections and bronchiolitis disease severity.