Jinjun Jiang

The role of aquaporin-1 (AQP1) expression in a murine model of lipopolysaccharide-induced acute lung injury.

A murine model of lipopolysaccharide (LPS)-induced acute lung injury (ALI) was used to evaluate whether aquaporin-1 (AQP1) is involved in lung inflammation and lung edema formation. Swiss strain mice (n = 122) had LPS (5 mg/kg) instilled intratracheally (IT), and were then treated with either 0.9 % saline or dexamethasone (5 mg/kg/day). Mice were euthanized at 2 days and 7 days after treatment. Inflammatory cytokines (TNF-alpha, IL-6), protein concentration in bronchoalveolar lavage (BAL) fluid, lung wet-to-dry weight ratio, histology, immunohistochemistry, and AQP1 Western blot were performed. Lung wet-to-dry weight ratio and lung vascular permeability were also measured in the AQP1 knockout mice (n = 9) that received IT LPS (5 mg/kg) at 2 days. Intratracheal instillation of LPS produced a severe lung injury at 2 days, characterized by elevation of TNF-alpha, IL-6 in the BAL fluid, and by histological changes consistent with increased lung vascular permeability and neutrophil infiltration. AQP1-immunoreactivity in the pulmonary capillary endothelium was reduced at 2 days and 7 days. Administration of dexamethasone improved LPS-induced ALI and retained expression of AQP1. However, depletion of AQP1 did not affect lung edema formation, lung vascular permeability, or lung histology. The results suggest that although AQP1 expression is decreased after lung injury, depletion of AQP1 does not alter lung inflammation and lung edema induced by LPS.

Continuous intra-arterial blood pH monitoring in rabbits with acid–base disorders

The acid-base balance of arterial blood is important for the clinical management of seriously ill patients, especially patients with acute lung injury or acute respiratory distress syndrome. We developed a novel fluorosensor for continuous blood pH monitoring and evaluated its performance both in vitro and in vivo in rabbits with acid-base disorders. The pH sensor is made of N-allyl-4-piperazinyl-1, 8-napthalimide and 2-hydroxyethyl methacrylate, which were bonded at the distal end of the optical fiber. The fluorescence intensity increased as the pH decreased with good reproducibility, selectivity and linearity in the pH range of 6-8. The pH measurement precision was 0.03 ± 0.03 pH units with a bias of -0.02 ± 0.04 (n = 105) and -0.00 ± 0.05 pH units (n=189) in rabbits with metabolic and respiratory acid-base orders, respectively. The optical pH sensor can accurately measure pH fluctuations with a fast response and is a promising candidate for continuous in-line measurements of blood pH in critical care patients.

Development of fiber optic fluorescence oxygen sensor in both in vitro and in vivo systems.

The accurate measurement of arterial blood oxygen partial pressure often plays an important role in the clinical assessment of patients with respiratory conditions such as an acute exacerbation of chronic obstructive pulmonary disease and acute lung injury/adult respiratory distress syndrome. An oxygen-sensitive fluorescence indicator with high biocompatibility was synthesized and then fabricated to the end of an optical fiber. The properties and accuracy of this oxygen sensor were investigated in vitro using physiologic solutions under varying conditions or human blood, and in vivo by obtaining measurements after inserting this optical sensor into the collateral circulation system of rabbits. The sensitivity of the oxygen sensor was relatively stable during altered conditions of pH, P(CO2), osmolality, and protein concentration in solutions and during alterations of oxygen and nitrogen content in human blood. There was a linear correlation between the reciprocal value of the fluorescence intensity and Pa(O2) in both in vivo and in vitro experiments (animal arterial circulation and human blood). Our results suggest that this oxygen-sensitive fluorescence indicator, which has a high biocompatibility, may have the potential for use in real-time monitoring of blood oxygen partial pressure in various clinical settings.The accurate measurement of arterial blood oxygen partial pressure often plays an important role in the clinical assessment of patients with respiratory conditions such as an acute exacerbation of chronic obstructive pulmonary disease and acute lung injury/adult respiratory distress syndrome. An oxygen-sensitive fluorescence indicator with high biocompatibility was synthesized and then fabricated to the end of an optical fiber. The properties and accuracy of this oxygen sensor were investigated in vitro using physiologic solutions under varying conditions or human blood, and in vivo by obtaining measurements after inserting this optical sensor into the collateral circulation system of rabbits. The sensitivity of the oxygen sensor was relatively stable during altered conditions of pH, P(CO2), osmolality, and protein concentration in solutions and during alterations of oxygen and nitrogen content in human blood. There was a linear correlation between the reciprocal value of the fluorescence intensity and Pa(O2) in both in vivo and in vitro experiments (animal arterial circulation and human blood). Our results suggest that this oxygen-sensitive fluorescence indicator, which has a high biocompatibility, may have the potential for use in real-time monitoring of blood oxygen partial pressure in various clinical settings.

Preventive effects of curcumin and dexamethasone on lung transplantation-associated lung injury in rats.

Objective:To investigate potential effects of curcumin or dexamethasone on lung transplantation-associated lung injury. Design:Prospective, randomized, controlled study. Setting:Research laboratory. Subjects:Adult male Sprague-Dawley rats. Interventions:Sham-operated rats were used as time-matched controls. Experimental rats were subjected to unilateral orthotopic lung transplantation with 4 hrs of cold ischemia followed by 2 hrs (or 24 hrs) of reperfusion. Animals were randomly assigned to vehicle-, curcumin-, or dexamethasone-treated groups. Measurements and Main Results:Transplantation-associated lung injury was characterized by an increased alveolar-capillary permeability and myeloperoxidase activity and decreased levels of arterial oxygen tension/inspired oxygen concentration ratio. Pretreatment with curcumin and dexamethasone significantly prevented barrier disruption, lung edema, tissue inflammation, and decreased Pao2 at the early stage of posttransplantation. Nuclear factor-&kgr;B in transplanted lungs was activated, accompanied by an increase in messenger RNA levels and protein content of tumor necrosis factor-α, interleukin-6, and matrix metalloproteinase-9 in lung graft. Those changes were prevented by pretreatment with curcumin and dexamethasone. Conclusions:Curcumin can be an alternative therapy for protecting lung transplantation-associated injury by suppressing nuclear factor-&kgr;B-mediated expression of inflammatory genes.

SOCS3 was induced by hypoxia and suppressed STAT3 phosphorylation in pulmonary arterial smooth muscle cells

Recently identified suppressors of cytokine signaling (SOCS) have been proposed as negative regulators of cytokine signaling, which have distinct mechanisms of inhibiting JAK-STAT pathway. In this study, using cultures of rat primary pulmonary vascular smooth muscle cells (PASMC), we found that hypoxia induced strongly STAT3 phosphorylation by up to four-fold. At the same time, mRNA for the endogenous cytokine signaling repressor SOCS3, but not SOCS1, was markedly induced in PASMC as early as 2h following hypoxic stimulation. Furthermore, forced expression of SOCS3 gene suppressed tyrosine phosphorylation of STAT3 and transcription of c-myc gene by more than 70% and 60% in PASMC under hypoxic conditions, respectively. Additionally, we showed here that hypoxia enhanced nearly two-fold increase of PASMC proliferation and overexpression of SOCS3 gene downregulated hypoxia-induced PASMC proliferation by about 50%. The finding suggest that STAT3-dependent pathway is involved in the activation and proliferation of PASMC stimulated by hypoxia, and SOCS3 is a rapidly hypoxia-inducible gene and acts to inhibit activation of cellular signaling pathway in a classical negative feedback loop.

Genetic variants in the TIRAP gene are associated with increased risk of sepsis-associated acute lung injury

BackgroundToll like receptors (TLRs) signaling pathways, including the adaptor protein Mal encoded by the TIRAP gene, play a central role in the development of acute lung injury (ALI). Recently, the TIRAP variants have been described association with susceptibility to inflammatory diseases. The aim of this study was to investigate whether genetic variants in TIRAP are associated with the development of ALI.MethodsA case-control collection from Han Chinese of 298 healthy subjects, 278 sepsis-associated ALI and 288 sepsis alone patients were included. Three tag single nucleotide polymorphisms (SNPs) of the TIRAP gene and two additional SNPs that have previously showed association with susceptibility to other inflammatory diseases were genotyped by direct sequencing. The differences of allele, genotype and haplotype frequencies were evaluated between three groups.ResultsThe minor allele frequencies of both rs595209 and rs8177375 were significantly increased in ALI patients compared with both healthy subjects (odds ratio (OR) = 1.47, 95% confidence interval (CI):1.15-1.88, P = 0.0027 and OR = 1.97, 95% CI: (1.38-2.80), P = 0.0001, respectively) and sepsis alone patients (OR = 1.44, 95% CI: 1.12-1.85, P = 0.0041 and OR = 1.82, 95% CI: 1.28-2.57, P = 0.00079, respectively). Haplotype consisting of these two associated SNPs strengthened the association with ALI susceptibility. The frequency of haplotype AG (rs595209A, rs8177375G) in the ALI samples was significantly higher than that in the healthy control group (OR = 2.13, 95% CI: 1.46-3.09, P = 0.00006) and the sepsis alone group (OR = 2.24, 95% CI: 1.52-3.29, P = 0.00003). Carriers of the haplotype CA (rs595209C, rs8177375A) had a lower risk for ALI compared with healthy control group (OR = 0.69, 95% CI: 0.54-0.88, P = 0.0003) and sepsis alone group (OR = 0.71, 95% CI: 0.55-0.91, P = 0.0006). These associations remained significant after adjustment for covariates in multiple logistic regression analysis and for multiple comparisons.ConclusionsThese results indicated that genetic variants in the TIRAP gene might be associated with susceptibility to sepsis-associated ALI in Han Chinese population. However, the association needs to be replicated in independent studies.

Genetic Variation in the TNF Gene Is Associated with Susceptibility to Severe Sepsis, but Not with Mortality

Background Tumor necrosis factor (TNF) and TNF receptor superfamily (TNFR)-mediated immune response play an essential role in the pathogenesis of severe sepsis. Studies examining associations of TNF and lymphotoxin-α (LTA) single nucleotide polymorphisms (SNPs) with severe sepsis have produced conflicting results. The objective of this study was to investigate whether genetic variation in TNF, LTA, TNFRSF1A and TNFRSF1B was associated with susceptibility to or death from severe sepsis in Chinese Han population. Methodology/Principal Findings Ten SNPs in TNF, LTA, TNFRSF1A and TNFRSF1B were genotyped in samples of patients with severe sepsis (n = 432), sepsis (n = 384) and healthy controls (n = 624). Our results showed that rs1800629, a SNP in the promoter region of TNF, was significantly associated with risk for severe sepsis. The minor allele frequency of rs1800629 was significantly higher in severe sepsis patients than that in both healthy controls (Padj = 0.00046, odds ratio (OR)adj = 1.92) and sepsis patients (Padj = 0.002, ORadj = 1.56). Further, we investigated the correlation between rs1800629 genotypes and TNF-α concentrations in peripheral blood mononuclear cells (PBMCs) of healthy volunteers exposed to lipopolysaccharides (LPS) ex vivo, and the association between rs1800629 and TNF-α serum levels in severe sepsis patients. After exposure to LPS, the TNF-α concentration in culture supernatants of PBMCs was significantly higher in the subjects with AA+AG genotypes than that with GG genotype (P = 0.007). Moreover, in patients with severe sepsis, individuals with AA+AG genotypes had significantly higher TNF-α serum concentrations than those with GG genotype (Padj = 0.02). However, there were no significant associations between SNPs in the four candidate genes and 30 day mortality for patients with severe sepsis. Conclusions/Significance Our findings suggested that the functional TNF gene SNP rs1800629 was strongly associated with susceptibility to severe sepsis, but not with lethality in Chinese Han population.

Role of aquaporin and sodium channel in pleural water movement

The role of the ENaC sodium channel and aquaporin-1 (AQP1) water channel on pleural fluid dynamics in mice was investigated. 0.25 ml of hypertonic or isosmolar fluid was infused into the pleural space in anesthetized wildtype and AQP1 null mice. Pleural fluid was sampled at specified times to quantify the osmolality and volume. The sodium channel activator terbutaline increased isosmolar fluid clearance by 90% while the sodium channel inhibitor amiloride decreased it by 15%, but had no effect on osmotically driven water transport. AQP1 deletion significantly decreased osmotic water transport in pleural space by twofold, but it had no effect on isosmolar fluid clearance. Pretreatment with dexamethasone increased pleural osmotic fluid entry by 25%, while intravenous injection of HgCl2 decreased osmotic pleural water movement by 43%. These results provided evidence for a role of a sodium channel in pleural fluid absorption; AQP1 plays a major role in osmotic liquid transport but it does not affect isosmolar fluid clearance.

Genetic variation in the TNF receptor-associated factor 6 gene is associated with susceptibility to sepsis-induced acute lung injury

BackgroundRecent studies showed that overwhelming inflammatory response mediated by the toll-like receptor (TLR)-related pathway was important in the development of acute lung injury (ALI). The aim of this study was to determine whether common genetic variation in four genes of the TLR signaling pathway were associated with sepsis-induced ALI susceptibility and risk of death in Chinese Han population.MethodsFourteen tag single nucleotide polymorphisms (tagSNPs) in MyD88, IRAK1, IRAK4 and TRAF6 were genotyped in samples of sepsis-induced ALI (n = 272) and sepsis alone patients (n = 276), and tested for association in this case-control collection. Then, we investigated correlation between the associated SNP and the mRNA expression level of the corresponding gene. And we also investigated correlation between the associated SNP and tumor necrosis factor alpha (TNF-α) as well as interleukin-6 (IL-6) concentrations in peripheral blood mononuclear cells (PBMCs) exposed to lipopolysaccharides (LPS) ex vivo. The mRNA expression level was determined using real-time quantitative Polymerase Chain Reaction (PCR) assays, and concentrations of TNF-α and IL-6 were measured by enzyme-linked immunosorbent assay (ELISA).ResultsThe association analysis revealed that rs4755453, an intronic SNP of TRAF6, was significantly associated with susceptibility to sepsis-induced ALI. The C allele frequency of rs4755453 in the sepsis alone group was significantly higher than that in the sepsis-induced ALI group (P = 0.00026, odds ratio (OR) = 0.52, 95% confidence interval (CI) 0.37–0.74). These associations remained significant after adjustment for covariates in multiple logistic regression analysis and for multiple comparisons. TRAF6 mRNA expression levels in PBMCs from homozygotes of the rs4755453G allele were significantly higher than that in heterozygotes and homozygotes of the rs4755453C allele at baseline (P = 0.012 and P = 0.003, respectively) as well as after LPS stimulation (P = 0.009 and P = 0.005). Moreover, the concentrations of TNF-α and IL-6 in cell culture supernatants were also significantly higher in the subjects with rs4755453GG genotype than in subjects with CG and CC genotype. None of the 14 tagSNPs showed associations with risk of death and severity among ALI cases.ConclusionsOur findings indicated that common genetic variants in TRAF6 were significantly associated with susceptibility to sepsis-induced ALI in Chinese Han population. This was the first genetic evidence supporting a role for TRAF6 in ALI.

Real-time monitoring of blood carbon dioxide tension by fluorosensor

A new intravascular fluorosensor was developed and validated for inline P(CO)₂monitoring. The P(CO)₂sensor was based on the fluorescent indicator 1-hydroxypyrene-3,6,8-trisulfonate. The P(CO)₂sensor was then immersed in various solutions in vitro and carotid artery bypass of rabbits in vivo for testing. Changes of P(CO)₂in solutions and blood were created by bubbling CO2/N2 and hyperventilation/hypoventilation, respectively. The changes of fluorescent intensity over P(CO)₂ range of 14-150 mmHg was linear. The resolution of the whole sensor system was 1 mmHg, with a bias ± SD of -0.1 ± 2.9 mmHg and precision ± SD of 2.1 ± 1.9 mmHg. The sensor signal has been stable during measurement for at least 25h and was insensitive to fluctuations of ions concentration and osmosis at pathophysiological limits. The performance of the sensor is in agreement with blood gas analyzer in a wide range of P(CO)₂and it is qualified for continuous intravascular measurement of blood P(CO)₂at various conditions.