The study is designed to observe the mechanism of Tongfu Xiefei Guanchang Solution(TFXF) in the treatment of acute lung injury(ALI) in rats by improving intestinal barrier and intestinal flora structure via p38 mitogen-activated protein kinase(p38 MAPK)/myosin light chain kinase(MLCK) signaling pathway. Sixty SPF-grade Wistar rats were randomly divided into the control(CON) group, lipopolysaccharide(LPS) group(7.5 mg·kg~(-1)), LPS + dexamethasone(DEX) group(3.5 mg·kg~(-1)), LPS + high-dose(HD)-TFXF group(14.74 g·kg~(-1)), LPS + middle-dose(MD)-TFXF group(7.37 g·kg~(-1)), and LPS + low-dose(LD)-TFXF group(3.69 g·kg~(-1)). ALI model of the rat was established by intraperitoneal injection of LPS. The lactate dehydrogenase(LDH) activity and total protein concentration in the bronchoalveolar lavage fluid(BALF) were measured; tumor necrosis factor-α(TNF-α) and interleukin-1β(IL-1β) levels in lung and colon tissue of rats were detected by enzyme linked immunosorbent assay(ELISA). Hematoxylin-eosin(HE) staining was used to observe the pathological expression in the lung and colon tissue of rats. The mRNA expression of p38 MAPK, TNF-α, and IL-1β in rat lung tissue was determined by real-time fluorescence quantitative polymerase chain reaction(real-time PCR). Western blot was used to detect the protein expression related to the p38 MAPK/MLCK signaling pathway in the colon tissue of rats. 16S rRNA sequencing was used to detect changes in the composition and content of intestinal flora in rats, and correlation analyses were performed to explore the regulatory role of intestinal flora in improving ALI in rats. The results showed that compared with those in the LPS group, the histopathological scores of lung and colon tissue, LDH activity, and total protein concentration in BALF were significantly reduced in rats in all groups after drug administration. Except for the LPS + LD-TFXF group, the remaining groups significantly reduced the levels of TNF-α and IL-1β in the lung and colon tissue of rats. The protein expressions of phosphorylated p38 mitogen-activated protein kinase(p-p38 MAPK)/p38, phosphorylated myosin light chain(p-MLC)/myosin light chain 2(MLC2), and MLCK in colon tissue of rats in each drug administration group were significantly decreased. The mRNA expression levels of p38 MAPK, TNF-α, and IL-1β were significantly reduced in the LPS + HD-TFXF group. 16S rRNA sequencing results showed that the abundance of intestinal flora was significantly higher in the LPS + HD-TFXF group, and intestinal floras including Sobs, Shannon, and Npshannon were significantly higher. The β-diversity distribution of intestinal flora tends toward the CON group, and the abundance of Firmicutes was significantly higher. The abundance of Proteobacteria was significantly reduced; the abundance of Bacteroides was significantly reduced, and the abundance of Ruminococcus was significantly higher. The main species differences were Blautia, Roseburia＿sp＿499, and Butyricicoccus. TNF-α and IL-1β of lung tissue were negatively correlated with Muribaculaceae, unclassified norank＿f＿Eubacterium＿coprostanoligenes, and Ruminococcus and positively correlated with Bacteroides. Meanwhile, TNF-α and IL-1β of colon tissue were negatively correlated with unclassified norank＿f＿Eubacterium＿coprostanoligenes and Ruminococcus and positively correlated with Bacteroides. The predicted biological function of the flora was related to the biosynthesis of secondary metabolites, amino acid biosynthesis, sugar metabolism, and oxidative phosphorylation. The above studies show that TFXF can repair lung and colon tissue structure and regulate inflammatory factor levels by modulating the abundance and diversity of intestinal flora species in ALI rats. Its mechanism of action in ameliorating ALI in rats may be related to the inhibition of inflammation, improvement of intestinal mucosal permeability, and maintenance of intestinal flora homeostasis and barrier through the p38 MAPK/MLCK signaling pathway.
Animals ; Acute Lung Injury/genetics* ; Rats ; p38 Mitogen-Activated Protein Kinases/genetics* ; Drugs, Chinese Herbal/pharmacology* ; Myosin-Light-Chain Kinase/genetics* ; Male ; Gastrointestinal Microbiome/drug effects* ; Rats, Wistar ; Signal Transduction/drug effects* ; Interleukin-1beta/metabolism* ; Tumor Necrosis Factor-alpha/metabolism* ; Lung/metabolism* ; Intestinal Mucosa/metabolism* ; Humans

Genetically encoded Ca(2+) indicators (GECI) are important for the measurement of Ca(2+) in vivo. GCaMP2, a widely-used GECI, has recently been iteratively improved. Among the improved variants, GCaMP3 exhibits significantly better fluorescent intensity. In this study, we developed a new GECI called GCaMPJ and determined the crystal structures of GCaMP3 and GCaMPJ. GCaMPJ has a 1.5-fold increase in fluorescence and 1.3-fold increase in calcium affinity over GCaMP3. Upon Ca(2+) binding, GCaMP3 exhibits both monomeric and dimeric forms. The structural superposition of these two forms reveals the role of Arg-376 in improving monomer performance. However, GCaMPJ seldom forms dimers under conditions similar to GCaMP3. St ructural and mutagenesis studies on Tyr-380 confirmed its importance in blocking the cpEGFP β-barrel holes. Our study proposes an efficient tool for mapping Ca(2+) signals in intact organs to facilitate the further improvement of GCaMP sensors.
Calcium ; chemistry ; metabolism ; Calmodulin ; chemistry ; genetics ; metabolism ; Crystallography, X-Ray ; Dimerization ; Green Fluorescent Proteins ; chemistry ; genetics ; metabolism ; Histidine ; chemistry ; genetics ; metabolism ; Hydrogen-Ion Concentration ; Myosin-Light-Chain Kinase ; chemistry ; genetics ; metabolism ; Peptide Fragments ; chemistry ; genetics ; metabolism ; Protein Structure, Tertiary ; Recombinant Fusion Proteins ; biosynthesis ; chemistry ; genetics

OBJECTIVETo determine the role of asymmetric dimethylarginine (ADMA) in acute lung injury induced by cerebral ischemia/reperfusion (I/R) injury in rats.

METHODSAdult male SD rats were randomly divided into 4 groups, namely the sham-operated group (S), cerebral I/R model group, ADMA+I/R group, and dimethylarginine dimethylaminohydrolase (DDAH)+I/R group. In the latter 3 groups, acute lung injury was induced by left middle cerebral artery occlusion for 120 min. After a 24-h reperfusion, the rats were sacrificed and the activities of nitric oxide synthase (NOS) and contents of nitric oxide (NO) were measured using reductase and colorimetric assay. The mRNA and protein expressions of protein kinase C (PKC) and myosin light chain kinase (MLCK) in the lung tissues were detected with RT-PCR and Western blotting, respectively. The contents of ADMA in the bronchoalveolar lavage fluid (BALF) and blood flowing into and out of the lungs were measured by ELISA.

RESULTSCerebral I/R injury caused significantly elevated ADMA levels in the BALF and blood flowing into the lungs, and obviously lowered the NO concentration and NOS activity in the lung tissues (P<0.05). Following cerebral I/R injury, MLCK and PKC mRNA and protein expressions were significantly upregualted in the lung tissues (P<0.05). Exogenous DDAH obviously decreased the levels of ADMA in the BALF and blood flowing into the lungs, increased NO concentration and NOS activity, and down-regulated MLCK and PKC mRNA and protein expressions in lung tissues of rats with cerebral I/R injury (P<0.05).

CONCLUSIONADMA contributes to the development of acute lung injury following cerebral I/R injury in rats by upregulating MLCK and PKC expression. ADMA may serve as a novel therapeutic biomarker and a potential therapeutic target for acute lung injury induced by cerebral I/R injury.

Acute Lung Injury ; etiology ; physiopathology ; Animals ; Arginine ; analogs & derivatives ; metabolism ; pharmacology ; Brain Ischemia ; complications ; Male ; Myosin-Light-Chain Kinase ; genetics ; metabolism ; Nitric Oxide Synthase ; antagonists & inhibitors ; Protein Kinase C ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury ; complications ; physiopathology ; Up-Regulation ; drug effects