Molecular pathology of pulmonary surfactants and cytokines in drowning compared with other asphyxiation and fatal hypothermia

Abstract

Drowning involves complex fatal factors, including asphyxiation and electrolyte/osmotic disturbances, as well as hypothermia in cold water. The present study investigated the molecular pathology of pulmonary injury due to drowning, using lung specimens from forensic autopsy cases of drowning (n = 21), acute mechanical asphyxia due to neck compression and smothering (n = 24), and hypothermia (cold exposure, n = 11), as well as those of injury (n = 23), intoxication (n = 13), fire fatality (n = 18), and acute cardiac death (n = 9) for comparison. TaqMan real-time reverse transcription polymerase chain reaction was used to quantify messenger RNA (mRNA) expressions of pulmonary surfactant-associated proteins A and D (SP-A and SP-D), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-10. SP-A and SP-D mRNA levels were lower for drowning, mechanical asphyxiation, fire fatality, and acute cardiac deaths than for hypothermia and injury. TNF-α, IL-1β, and IL-10 mRNA levels were higher for drowning or for drowning and injury than for other groups; there was no significant difference between fire fatality, involving airway injury due to inhalation of hot/irritant gases, and other control groups. These observations suggest characteristic molecular biological patterns of pulmonary injury involving suppression of pulmonary surfactants and activation of early-phase mediators of inflammation in drowning, with high mRNA expression levels of pulmonary surfactants in fatal hypothermia; however, there was no significant difference among these markers in immunohistochemical detection, except for SP-A. These mRNA expressions can be used as markers of pulmonary injury to assist in investigations of the pathophysiology of drowning and fatal hypothermia in combination with other biochemical and biological markers.

Molecular pathology of pulmonary edema in forensic autopsy cases with special regard to fatal hyperthermia and hypothermia

“…Such autopsy data is important for understanding the pathophysiology of human death; however, it has been reported that the stability of housekeeping gene expressions may be different among the tissues and affected by the cause of death, suggesting that at least four endogenous references should be used in human postmortem cardiac muscle, skeletal muscle and brain [38]. Although our preliminary experiments using human postmortem lung tissue showed good correlations among commonly used housekeeping genes, including B2M, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and betaactin (unpublished data), as well as gradual and parallel degradation with target genes [39], further cooperation and investigation will be needed to establish the efficacy of individual endogenous references in practical application.…”

Stability of endogenous reference genes in postmortem human brains for normalization of quantitative real-time PCR data: comprehensive evaluation using geNorm, NormFinder, and BestKeeper

“…Accurate and reliable relative RT-qPCR requires ideal amplification efficiencies of target and reference genes [10]; selection of adequate reference genes is essential. Previous studies suggested successful application of conventional reference genes for the myocardium, lungs, kidneys, and skeletal muscle [7,[11][12][13][14]. For estimating the amplification efficiency, however, conventional standard curve method is time consuming, requiring the production of repeatable and reliable standards [15,16].…”

Comprehensive Histological and Immunochemical Forensic Studies in Deaths Occurring in Custody

“…Consequently, the presence of aggregates of surfactant protein A would suggest mechanical asphyxia or drowning, and their absence would suggest an alternative cause of death. Messenger RNA has also been studied in these cases, but there is limited information with this method [20]. …”