CC16 Regulates Inflammation, ROS Generation and Apoptosis in Bronchial Epithelial Cells during Klebsiella pneumoniae Infection

Selenomethionine attenuates Klebsiella pneumoniae-induced jejunal injury in rabbits by inhibiting the TLR4/NF-κB pathway

Klebsiella pneumoniae (KP) infection often causes diarrhoea and intestinal barrier damage in young rabbits. The objective of this study was to explore whether selenomethionine (SeMet) can attenuate the jejunal injury caused by KP in rabbits. Therefore, we investigated the protective effect of SeMet by performing haematoxylin-eosin (HE), alcian blue periodic acid Schiff (AB-PAS), proliferating nuclear antigen (PCNA), TUNEL and immunofluorescence staining. In addition, the concentrations of Interleukin-1β (IL-1β), Interleukin-6 (IL-6), Tumor necrosisfactor-α (TNF-α) and Interleukin-10 (IL-10) in the jejunal tissue were detected by enzyme-linked immunosorbent assay (ELISA). The results showed that after KP infection, the productivity of rabbits decreased, and the mucosal barrier of the jejunum was damaged. Moreover, KP induced jejunal inflammation, activated the TLR4/NF-κB signalling pathway, and promoted the expression of the IL-1β, IL-6, and TNF-α. In addition, KP increased the apoptotic response of intestinal cells and upregulated the expression of caspase-3 and caspase-9. SeMet pretreatment significantly decreased the degree of intestinal epithelial cell apoptosis. Therefore, we showed that SeMet can reduce inflammation and enhance intestinal barrier function to improve the production performance of rabbits infected with KP.

Oxidative stress promotes lipid-laden macrophage formation via CYP1B1

Emerging evidence suggests that lipid-laden macrophages (LLM) participate in lung damage in various clinical conditions. However, the mechanisms involved in LLM formation are not fully understood. In this study, we aimed to investigate the link between reactive oxygen species (ROS) and LLM formation. We found that ROS triggered by cigarette smoke extract (CSE) or H2O2 significantly promoted LLM formation. Given the key role of ROS in LLM formation, we further demonstrated that LLM formation is induced by various ROS-producing stimuli, including bacteria, oxidized low-density lipoprotein (OxLDL), hyperoxia, and E-cigarette vapor extract (EVE). Meanwhile, cytochrome P450 family-1 subfamily B member 1 (CYP1B1) was highly upregulated in lung macrophages from chronic obstructive pulmonary disease (COPD) patients and CSE-treated macrophages. Functionally, CYP1B1 contributes to the CSE-induced lipid accumulation and LLM formation. CYP1B1 expression and LLM formation were effectively suppressed by antioxidant N-acetylcysteine (NAC) and carvedilol. The formation of LLM was also associated with classically activated M1 but not the M2 state. CSE-induced LLM showed time-dependent alterations in inflammatory response and phagocytic ability. In summary, our study highlights the role of oxidative stress in LLM formation. CYP1B1 contributes to ROS-induced LLM formation and may serve as a therapeutic target for reducing LLM-induced lung damage.

Effects of Bacillus coagulans on kidney injury caused by Klebsiella pneumoniae in rabbits

Klebsiella pneumoniae (KP) is a zoonotic conditionally pathogenic bacterium with a high prevalence of infection. It often induces purulent inflammation of the rabbit lungs, kidneys and other tissues, with high morbidity and mortality. Bacillus coagulans (BC) has the ability to regulate the balance of host intestinal flora and improve host immunity. However, the mechanism of the protective effect of BC on KP-induced kidney injury in rabbits is not clear. To explore this, we randomly divided fifty 35-day-old Eyplus rabbits into five groups: control, KP, low-dose BC (LBC), medium-dose BC (MBC) and high-dose BC (HBC). On the 1st day of the experiment, rabbits in LBC, MBC and HBC groups were fed diets containing 1 × 106 CFU/g, 5 × 106 CFU/g and 1 × 107 CFU/g BC, respectively, and rabbits in CK and KP groups were fed basal diets. On the 8th day, each rabbit in the KP, LBC, MBC and HBC groups was infused with 4 mL of 1 × 1011 CFU/mL KP bacterial solution, and the CK group was infused with the same amount of sterilised saline for a total of 7 days. Rabbit kidney tissues were collected on the 15th d. HE staining was used to observe the pathological changes of rabbit kidney tissues, oxidative stress-related indexes were detected by biochemical kits, and the content of inflammatory factors and apoptosis-related factors in kidney tissues were detected by ELISA. The results showed that KP disrupts the normal structure of the kidney, induces oxidative stress and inflammatory responses, and mediates apoptosis by regulating the levels of Bcl-2 family proteins. BC pretreatment significantly reduced kidney structural damage, oxidative stress, inflammatory response, and apoptosis in rabbits. To alleviate KP-induced kidney injury by increasing the activity of antioxidant enzymes and the content of anti-apoptotic proteins. Compared with the LBC group and the HBC group, the remission effect was more pronounced in the MBC group. Therefore, in this study, the effect of 5 × 106 CFU/g BC was more significant.

Inhaled tea polyphenol-loaded nanoparticles coated with platelet membranes largely attenuate asthmatic inflammation

BACKGROUND

Tea polyphenols (TPs), prominent constituents of green tea, possess remarkable antioxidant and anti-inflammatory properties. However, their therapeutic potential is limited due to low absorption and poor bioavailability. To address this limitation and enhance their efficacy, we developed a biomimetic nanoplatform by coating platelet membrane (PM) onto poly-lactic-co-glycolic acid (PLGA) nanoparticles (NPs) to create targeted delivery vehicles for TPs (PM@TP/NPs) to the inflamed tissues in asthma.

METHODS

After synthesizing and characterizing PM@TP/NPs, we assessed their biocompatibility and biosafety through cell viability assays, hemolysis tests, and inflammation analysis in vivo and in vitro. The therapeutic effect of PM@TP/NPs on asthma was then evaluated using a mouse model of HDM-induced asthma. Additionally, PM@TP/NPs-mediated reactive oxygen species (ROS) scavenging capacity, as well as the activation of signaling pathways, were analyzed in HBE cells and asthmatic mice via flow cytometry, RT-qPCR, and western blotting.

RESULTS

Compared with free TPs, PM@TP/NPs demonstrated excellent biocompatibility and safety profiles in both in vitro and in vivo, as well as enhanced retention in inflamed lungs. In HDM-induced mouse asthma model, inhaled PM@TP/NPs largely attenuated lung inflammation and reduced the secretion of type 2 pro-inflammatory cytokines in the lungs compared to free TPs. The therapeutic effects of PM@TP/NPs on asthma might be associated with an enhanced ROS scavenging capacity, increased activation of the Nrf2/HO-1 pathway, and decreased activation of the CCL2/MAPK and TLR4/NF-κB pathway in the lungs.

CONCLUSIONS

Our findings demonstrate that inhalation of PM@TP/NPs largely attenuated lung inflammation in HDM-induced asthmatic mice. These results suggest that PM@TP/NPs might be a novel therapeutic strategy for asthma.

Club Cell Secretory Protein-16 (CC16) as a Prognostic Biomarker for COVID-19 and H1N1 Viral Infections

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and H1N1 viruses are inflammatory lung pathogens that can lead to acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). ALI/ARDS are still life-threatening diseases in critically ill patients with 30-40% mortality in the last decade. Currently, there are no laboratory tests for the early diagnosis or prognosis of ALI/ARDS. Club cell secretory protein (CC16) has been investigated as a potential biomarker of lung epithelial damage in various lung diseases. In this study, we evaluated whether plasma CC16 reflects the severity of COVID-19 and H1N1 infections. The plasma CC16 levels showed no significant differences between H1N1 and COVID-19 groups (p = 0.09). Among all subjects, CC16 levels were significantly higher in non-survivors than in survivors (p = 0.001). Upon the area under the receiver operating characteristic (AUROC) analysis, CC16 had an acceptable value to distinguish survivors and non-survivors (p = 0.002). In the COVID-19 group, plasma CC16 levels moderately correlated with the Acute Physiology and Chronic Health Evaluation II (APACHE II) score (r = 0.374, p = 0.003) and Sequential Organ Failure Assessment (SOFA) score (r = 0.474, p < 0.001). In the H1N1 group, a positive correlation was observed between the CC16 levels and hospital length of stay (r = 0.311, p = 0.022). Among all the patients, weak correlations between plasma CC16 levels with the SOFA score (r = 0.328, p < 0.001) and hospital length of stay (r = 0.310, p < 0.001) were observed. Thus, circulating CC16 might reflect the severity of COVID-19 and H1N1 infections.

Associations of Serum Clara Cell Protein 16 with Severity and Prognosis in Adults with Community-Acquired Pneumonia

Background

Clara cell protein 16 (CC16) has multiple functions, including antioxidant, anti-inflammatory, and immune regulation properties. Nevertheless, the concrete function of CC16 in adult patients with community-acquired pneumonia (CAP) remained blurred.

Methods

A total of 541 adult patients with CAP were recruited on admission. Peripheral blood specimens, clinical parameters, and demographic characteristics were collected. The concentration of serum CC16 was evaluated through ELISA. The relationships between serum CC16 and clinical parameters were appraised by Spearman or Pearson correlative analyses. The correlations of serum CC16 with severity and prognosis were assessed using linear or logistic regression models.

Results

The level of CC16 was gradually decreased across with the elevated severity scores system of CAP. After treatment, the level of serum CC16 was upregulated. Correlative analyses found that serum CC16 was negatively related to inflammatory cytokines. Additionally, multivariate linear and logistic regression models revealed that serum CC16 was inversely associated with severity scores system. In addition, reduced serum CC16 on admission elevated the risks of vasoactive agent usage, ICU admission, and death during hospitalization. We observed an almost discriminatory ability for severity and death between serum CC16 and severity scores system, and were all obviously elevated compared to routine inflammatory and infectious markers.

Conclusion

There are substantially inverse correlations between serum CC16 level on admission with severity scores and poorly prognostic outcomes, indicating that CC16 is involved in the pathophysiological process of CAP. This study is helpful for establishing the potential application of serum CC16 in risk evaluation and targeted treatment.

Polydatin prevent lung epithelial cell from Carbapenem-resistant Klebsiella pneumoniae injury by inhibiting biofilm formation and oxidative stress

Carbapenem-resistant Klebsiella pneumoniae (CRKP) causes severe inflammation in various infectious diseases, such as bloodstream infections, respiratory and urinary tract infections, which leads to high mortality. Polydatin (PD), an active ingredient of Yinhuapinggan granule, has attracted worldwide attention for its powerful antioxidant, anti-inflammatory, antitumor, and antibacterial capacity. However, very little is known about the effect of PD on CRKP. In this research, we evaluated the inhibitory effects of PD on both the bacterial level and the bacterial-cell co-culture level on anti-biofilm and efflux pumps and the other was the inhibitory effect on apoptosis, reactive oxygen species (ROS), mitochondrial membrane potential (MMP) after CRKP induction. Additionally, we validated the mechanism of action by qRT-PCR and western blot in human lung epithelial cells. Firstly, PD was observed to have an inhibitory effect on the biofilm of CRKP and the efflux pump AcrAB-TolC. Mechanically, CRKP not only inhibited the activation of Nuclear Factor erythroid 2-Related Factor 2 (Nrf-2) but also increased the level of ROS in cells. These results showed that PD could inhibit ROS and activate Nrf-2 production. Together, our research demonstrated that PD inhibited bacterial biofilm formation and efflux pump AcrAB-TolC expression and inhibited CRKP-induced cell damage by regulating ROS and Nrf-2-regulated antioxidant pathways.

The Most Valuable Predictive Factors for Bronchopulmonary Dysplasia in Very Preterm Infants

INTRODUCTION

It is urgent to make a rapid screening of infants at the highest risk for bronchopulmonary dysplasia (BPD) via some succinct postnatal biomarkers, such as Ureaplasma Urealyticum (UU) infection and chest radiograph images.

METHODS

A retrospective study was performed. Moderate to severe BPD or death was set as the main outcome. The association between putative variables and the main outcome were assessed by bivariate analyses and logistic regression.

RESULTS

A total of 134 infants were enrolled. Bivariate analyses showed the gestational age, birth weight, appearances of diffuse opacities or grid shadows/interstitial opacities or mass opacities or cystic lucencies on chest radiographic images, a ductal diameter ≥1.5 mm and whether UU infection was associated with BPD. After adjustment by logistic regression, the risk of BPD with gestational age, sex and specific chest-radiographic manifestations remained significant.

CONCLUSIONS

Chest radiograph images (appearance of diffuse opacities or grid shadows/interstitial opacities or mass opacities or cystic lucencies) could provide a quick prediction of developing BPD in clinical practice, in addition to gestational age and sex. UU infection was not an independent risk factor for BPD.

Carbon disulfide exposure induced lung function reduction partly through oxidative protein damage: A cross-sectional and longitudinal analysis

Carbon disulfide (CS₂) exposure has been associated with lung function reduction in occupational population. However, evidence on the general population with relatively low CS₂ exposure is lacking and the mechanism involved remains largely unknown. Urinary CS₂ metabolite (2-mercaptothiazolidine-4-carboxylic acid, TTCA) and lung function were determined in the urban adults from the Wuhan-Zhuhai cohort at baseline in 2011-2012 and were repeated every 3 years. Cross-sectional and longitudinal associations between TTCA and lung function were estimated using linear mixed models. Inflammation and oxidative damage biomarkers in blood/urine were measured to evaluate their potential mediating roles involved. Cross-sectionally, participants in the highest quartile of TTCA level showed a 0.64% reduction in FEV₁/FVC and a -308.22 mL/s reduction in PEF, compared to those in the lowest quartile. Longitudinally, participants with consistently high TTCA level had annually -90.27 mL/s decline in PEF, compared to those with consistently low TTCA level. Mediation analysis revealed that plasma protein carbonyl mediated 49.89% and 22.10% of TTCA-associated FEV₁/FVC and PEF reductions, respectively. Conclusively, there was a cross-sectional and longitudinal association between CS₂ exposure and lung function reduction in the general urban adults, and protein carbonylation (oxidative protein damage) partly mediated lung function reduction from CS₂ exposure.

Extracellular vesicle-encapsulated CC16 as novel nanotherapeutics for treatment of acute lung injury

Acute lung injury (ALI) is still associated with high mortality. Growing evidence suggests that Club Cell Protein 16 (CC16) plays a protective role against ALI. However, the doses of recombinant CC16 (rCC16) used in preclinical studies are supraphysiological for clinical applications. Extracellular vesicles (EVs) are nanovesicles endogenously generated by mammalian cells. Our study demonstrated that CC16 is released via small EVs and EV-encapsulated CC16 (sEV-CC16) and has anti-inflammatory activities, which protect mice from lipopolysaccharide (LPS) or bacteria-induced ALI. Additionally, sEV-CC16 can activate the DNA damage repair signaling pathways. Consistent with this activity, we observed more severe DNA damage in lungs from Cc16 knockout (KO) than wild-type (WT) mice. Mechanistically, we elucidated that CC16 suppresses nuclear factor κB (NF-κB) signaling activation by binding to heat shock protein 60 (HSP60). We concluded that sEV-CC16 could be a potential therapeutic agent for ALI by inhibiting the inflammatory and DNA damage responses by reducing NF-κB signaling.

The traditional Chinese patented medicine Qingke Pingchuan granules alleviate acute lung injury by regenerating club cells

Qingke Pingchuan granules (QKPCG), a patented traditional Chinese medicine, clinically, are recommended for acute tracheobronchitis, cough, community-acquired pneumonia, and other respiratory diseases. However, its potential protective effect and mechanism of action in acute lung injury (ALI) have not been explored. We aimed to explore the mechanisms underlying the protective role of QKPCG in ALI. The therapeutic efficacy of QKPCG was investigated in a lipopolysaccharide (LPS)-induced ALI mouse model. Mice were divided into three groups, namely, the Control, LPS, and LPS + QKPCG groups. Mice in the LPS + QKPCG group were administered QKPCG intragastrically as a treatment once a day for a total of three days. QKPCG effectively increased survival and reduced lung injury in treated mice. It significantly reduced the LPS-induced expression of interleukin (IL)-6, tumor necrosis factor-α (TNF-α), IL-1α, and IL-1β. RNA-sequencing followed by real-time quantitative polymerase chain reaction validation suggested a critical role of the secretoglobin family 1A member 1 (Scgb1a1) gene in mediating the protective effect of QKPCG. Further, QKPCG reversed the LPS-induced downregulation of the Clara cell 10 kDa protein (CC10), a pulmonary surfactant protein encoded by Scgb1a1, which is mainly secreted by club cells in the lungs. Exogenous supplementation of CC10 alleviated LPS-induced ALI. Hematoxylin and eosin staining and enzyme-linked immunosorbent assay results further confirmed the anti-inflammatory properties of CC10, which were suggested as mediated via the inhibition of NFκB phosphorylation. In summary, our study provides evidence of the beneficial role of QKPCG in alleviating lung injury, mediated via the decreased disruption of club cells and higher expression of CC10, which leads to NFκB pathway inhibition.