[Experimental study on the expression and function of aquaporin-1 and aquaporin-5 in rats with acute lung injury induced by lipopolysaccharide].
OBJECTIVE
To investigate whether the expression and function of aquaporin-1 (AQP-1) is altered by tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) in primary rat lung microvessel endothelial cells (LMECs) after exposure to lipopolysaccharide (LPS), and to study the expressions of AQP-1 and AQP-5 in lung tissue of rats with acute lung injury (ALI) induced by LPS. The aim is to further clarify the pathogenesis of ALI/acute respiratory distress syndrome (ARDS).


METHODS
(1) In vitro: The third passage LMECs were randomly divided into LPS group, TNF-alpha group, IL-1beta group and DMEM control group, and the experimental groups were exposed to LPS, TNF-alpha and IL-1beta respectively. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to quantify AQP-1 mRNA changes and an immunocytochemistry method was used for determining AQP-1 protein changes in cultured rat LMECs. Isotope tracer technique was applied for the assay of the intra-cellular tritium water ((3)H2O) signal intensity in rat LMECs. (2) In vivo: Forty male Wistar rats were randomly divided into five groups: LPS 2 h group, LPS 4 h group, LPS 6 h group, LPS 8 h group and a control group, eight rats per group; The LPS treated groups served as the ALI models. RT-PCR was used to observe the changes of AQP-1 and AQP-5 mRNA and the immunohistochemistry method was used for determining AQP-1 and AQP-5 protein changes in ALI rats.


RESULTS
(1) In vitro: The expression of AQP-1 mRNA and protein in LMECs were decreased significantly in the LPS group (0.428 +/- 0.026, 0.366 +/- 0.009), the TNF-alpha group (0.446 +/- 0.029, 0.374 +/- 0.014) and IL-1beta group (0.454 +/- 0.023, 0.377 +/- 0.007) as compared to the DMEM control group (0.793 +/- 0.035, 0.660 +/- 0.013, respectively; all P < 0.01). The quantities of tritium water's permeability in the LPS group, the TNF-alpha group and the IL-1beta group [(726 +/- 58), (738 +/- 45), (774 +/- 44) counts per minute] were significantly less than that in the DMEM control group [(1 148 +/- 70) counts per minute, P < 0.01]. (2) In vivo: The expression levels of AQP-1 and AQP-5 mRNA in ALI rats (LPS 2 h group 0.409 +/- 0.018, 0.421 +/- 0.020; LPS 4 h group 0.421 +/- 0.023, 0.412 +/- 0.023; LPS 6 h group 0.435 +/- 0.020, 0.388 +/- 0.031; LPS 8 h group 0.438 +/- 0.016, 0.386 +/- 0.019, respectively) were significantly lower than that in the control group (0.794 +/- 0.015, 0.787 +/- 0.022; all P < 0.01).


CONCLUSIONS
AQP-1 and AQP-5 may play a role in abnormal fluid transportation and probably involve in the formation of pulmonary edema in ALI/ARDS.
Xie
Yan-ping
YP
Institute of Respiratory Medicine, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
Chen
Cai-ping
CP
Wang
Jian-chun
JC
Qian
Gui-sheng
GS
Wang
Ying-deng
YD
Xiao
Zhen-liang
ZL
D055371:Acute Lung Injury / Q000378:metabolism*; D000818:Animals; D051398:Aquaporin 1 / Q000378:metabolism*; D051402:Aquaporin 5 / Q000378:metabolism*; D053583:Interleukin-1beta / Q000009:adverse effects; D008070:Lipopolysaccharides / Q000009:adverse effects; D008168:Lung / Q000378:metabolism; D008297:Male; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D014409:Tumor Necrosis Factor-alpha / Q000009:adverse effects
D051402:Aquaporin 5; D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D051398:Aquaporin 1