Effects of Hyperoxia on the Dynamic Expression of Aquaporin5 in Premature Rats Lung Development

To explore the dynamic expression and role of Aquaporin5 ( AQP5) in lung development and hyperoxia lung injury, gestation 21-day Sprague-Dawley (SD) rats (term=22 days) were ran- domly assigned to air group and hyperoxia group within 12-24 h after birth. The rats in hypreoxia group were continuously exposed to about 85% oxygen and those in air group to room air. After 1 to 14 days of exposure, total lung RNA was extracted and the expression of AQP5 mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR). Immunohistochemistry and west- ern-blot were used to detect the expression of AQP5 protein. The results showed that the expression of AQP5 in premature rats lung could be detected at various time points after birth, and the positive staining was restricted to the type Ⅰ alveolar epithelial cells. In air group, the AQP5 expression was detected in a very low level at day 1, but exhibited a persistent increase after birth. Compared with the air group, the expression of AQP5 in hyperoxia group was increased at day 1, and had significant difference in mRNA level (P<0.05), but decreased significantly in mRNA and protein levels after 4 to 14 days (P<0.01 or P<0.05 respectively). It was concluded that AQP5 might play a key role in the alveolar period of premature rats by regulating the lung water balance. Hyperoxia exposure leads to a down-regulation of the AQP5 expression, which may be an important factor for the development of hyperoxia lung injury.

Aquaporin 5 Expression and Its Relationship to Apoptosis in Different Grades of Differentiated Non-Small Cell Lung Carcinoma

Aquaporin 5 has been recently found as an important oncogenic marker whose expression levels seem to be determined by the level of cellular differentiation. Despite aquaporin volume decrease (AVD) being the most conserved earliest event in apoptosis, there is still a paucity of studies exploring on aquaporin expression and its relationship with apoptosis in cancer. The aim of this study was to investigate the expression of aquaporin 5 channel protein and to explore on its relationship with apoptosis in well and poorly differentiated non-small cell lung carcinoma both in-vivo and in-vitro. Findings from the study showed that the expression of AQP5 both in-vivo and in-vitro was dependent on the type and degree of tumour differentiation. In-vivo, an increase in aquaporin 5 expression was associated with an increased apoptosis in both poorly and highly differentiated adenocarcinoma (AC) while there was no association between aquaporin 5 expression and apoptosis in both poorly and highly differentiated squamous cell carcinoma (SCC). In vitro, differentiation therapy in the form of ATRA decreased both cell proliferation and increased the expression of AQP5 in A549 cells. The cytomorphological changes, expression of differentiation markers and flow cytometry apoptotic results were dependent on the dose of ATRA treatment. In conclusion, a higher expression of aquaporin 5 was found to promote the rate of the apoptotic process in lung adenocarcinoma (AC).

The therapeutic mechanism of dexamethasone in lung injury induced by hydrogen sulfide

The lung is one of the primary target organs of hydrogen sulfide(H2S),as exposure to H2S can cause acute lung injury(ALI)and pulmonary edema.Dexamethasone(Dex)exerts a protective effect on ALI caused by exposure to toxic gases and is commonly used in the clinic;however,the underlying mechanisms remain elusive,and the dose is unclear.Methods:In vivo experiments:divided C57BL6 mice into 6 groups at random,12 in each group.The mice were exposed to H2S for 3 h and 5 or 50 mg/kg Dex pretreated before exposure,sacrificed 12 h later.The morphological changes of HE staining and the ultrastructural changes of lungs under transmission electron microscopy were evaluated.The wet/dry ratio of lung tissue was measured.Bronchial alveolar lavage fluid(BALF)protein content and lung permeability index were detected.The expression of AQP5 protein was measured by immunohistochemistry and Western Blot(WB).In vitro experiments:divided human lung adenocarcinoma cell line A549 into 4 groups.1μmol/L dexamethasone was added to pre-incubation.The WB analyzed the protein of p-ERK1/2,p-JNK,and p-p38 in MAPK pathway after 1 h of NaHS exposure;six hours after NaHS exposure,the AQP5 protein was measured by WB.Results:Dex treatment could significantly attenuate the H2S-induced destruction to the alveolar wall,increase the wet-to-dry weight ratio and decrease pulmonary permeability index,with high-dose dexamethasone seemingly functioning better.Additionally,our previous studies showed that aquaporin 5(AQP 5),a critical protein that regulates water flux,decreased both in a mouse and cell model following the exposure to H2S.This study indicates that tThe decrease in AQP 5 can be alleviated by Dex treatment.Additionally,the mitogen activated protein kinase(MAPK)pathway may be involved in the protective effects of Dex in ALI caused by exposure to H2S since H2Sinduced MAPK activation could be inhibited by Dex.Conclusion:The present results indicate that AQP 5 may be considered a therapeutic target for Dex in H2S or other hazardous gases-induced ALI.

Decreased expression of AQP1 and AQP5 in acute injured lungs in rats

OBJECTIVE: To determine if aquaporin1 (AQP1) and aquaporin5 (AQP5) are expressed in the alveolar capillary membrane in rats. Moreover, to investigate the alteration of AQP1 and AQP5 in acute injured lungs. METHODS: The distribution of AQP1 and AQP5 in alveolar capillary membrane were investigated by immunohistochemistry and immunoelectron microscopy with affinity-purified antibodies to human AQP1 and AQP5. To study the possibility that alveolar capillary membrane AQP1 and AQP5 undergo altered regulation, we established a rat model using alveolar instillation of lipopolysaccharide (LPS). RESULTS: Immunolabelling showed AQP1 was stained primarily in the microvascular endotheli a of normal lungs, while AQP5 was expressed in type I pneumocytes. Immunohisto chemical analysis showed a significant decrease in the expression of AQP1 and AQP5 in injured lungs at 4h-48h after LPS instillation. AQP1 protein was resumed partly at 24h after LPS instillation and steroid administration, whereas AQP5 was unchanged. CONCLUSION: The decreased expressions of AQP1 and AQP5 in injured lungs suggest that both of them may play a role in abnormal fluid transportation.

Aquaporin 5 is degraded by autophagy in diabetic submandibular gland

Autophagy is a catabolic process which is involved in the development of many diseases including diabetes mellitus and its complications. Hyposalivation is a common complication of diabetes mellitus, whereas its mechanism remains unclear. Here, we observed that the stimulated salivary flow rate of SMG was significantly decreased in db/db mice, a diabetic mice model. The expressions of aquaporin 5(AQP5), a water channel protein, were decreased, whereas the m RNA level of AQP5 was increased in SMGs of both diabetic patients and mice. Under transmission electron microcope, more autophagosomes were detected in diabetic SMGs. Expressions of autophagy related proteins LC3 II, Beclin-1 and ATG5 were increased, meanwhile autophagy substrate p62 was decreased in SMGs of diabetic patients and mice, indicating that autophagy was activated in diabetic SMG.Double immunofluorescence staining showed that the colocalization of AQP5 and LC3 was increased in SMGs of diabetic mice.In cultured SMG-C6 cells, high glucose(HG), but not high osmotic pressure, reduced AQP5 protein expression and induced autophagy. Moreover, inhibition of autophagy by 3-methyladenin, an autophagy inhibitor, or by autophagy-related gene 5 siRNA, decreased HG-induced AQP5 reduction in SMG-C6 cells. Additionally, the expression of p-p85, p-Akt and p-mTOR were decreased in HG-treated SMG-C6 cells. Pretreatment with 740 Y-P, a PI3 K agonist, significantly suppressed HG-induced autophagy and AQP5 degradation. Taken together, these results indicate that autophagy plays a crucial role in AQP5 degradation in diabetic SMG via PI3 K/Akt/mTOR signaling pathway, which contributes to the dysfunction of diabetic SMG. Our study provides a novel mechanism of diabetic hyposalivation.

Effect of Bushen Qingre Yuyin Decoction on Salivary Secretion, Spleen Index, Submandibular Gland Index, Submandibular Gland Histomorphology, and aqp5 Expression in the Nonobese Diabetic Mouse Model

Objective:The objective of this study was to observe the effect of Bushen Qingre Yuyin Decoction on the spleen index,submandibular gland index,salivary secretion,submandibular gland morphology,and aquaporin 5(AQP5)expression levels in the submandibular gland.Materials and Methods:Fifty 8-week-old nonobese diabetic(NOD)female mice were randomly divided into the following five groups:model;hydroxychloroquine;and high-,medium-,and low-dose Bushen Qingre Yuyin Decoction prescription.The blank group consisted of ten 8-week-old Balb/C rats.Bushen Yuyin Qingre Decoction was administered by gavage at 20,40,and 80 g/kg in the low-,medium-,and high-dose groups,respectively.The hydroxychloroquine group was administered hydroxychloroquine at a dose of 80 mg/kg by gavage.The normal and model groups were administered the same amount of saline.After the different administrations,the amount of salivary secretion in the mice was regularly observed.After 12 weeks,the mice were sacrificed,and their submandibular gland tissues were excised,stained with hematoxylin-eosin,and pathologically scored.AQP5 expression levels in the tissues were detected using real-time polymerase chain reaction.Results:The spleen index of mice in the high-dose group was higher than that in the model group(P<0.05),and the submandibular gland index of the hydroxychloroquine group and all the Bushen Qingre Yuyin Decoction prescription groups was higher than that in the model group(P<0.05).After 6 weeks,the salivary volume of the hydroxychloroquine group and all the Bushen Qingre Yuyin Decoction prescription groups was significantly higher than that of the model group(P<0.05);the amount of lymphocyte infiltration in mice among each administration group was significantly reduced(P<0.05);and the AQP5 expression levels in the submandibular glands of mice had significantly increased in the hydroxychloroquine and high-dose groups(P<0.05),with the high-dose group showing the best effect.Conclusion:Bushen Qingre Yuyin Decoction can effectively increase the spleen and submandibular gland indexes of NOD mice,increase the amount of salivary secretion,reduce lymphocyte infiltration in submandibular gland tissue,and significantly increase AQP5 expression levels,which may be positively correlated with the administered dose.