The Lung in Sepsis: Fueling the Fire

Jinhong decoction ameliorates injury in septic mice without disrupting the equilibrium of gut microbiota

Sepsis is a life-threatening condition and usually be treated with antibiotics, which however often has severe side effects. This work proposed a novel Chinese traditional medicine JINHONG (JH) decoction for therapy of sepsis. We first identified the chemical constituents of JH decoction by using high-performance liquid chromatography and mass spectrometry (HPLC-MS). Then, we constructed a model mouse for sepsis by using cecal ligation and puncture (CLP). Metagenomic sequencing method was used to compare the diversity and abundance of the gut microbiota between normal, disease model, JH decoction-treatment and antibiotic-treatment mice. Many indices including the number of platelets, CD62p and CD63 content, AQP2 and AQP8 level, as well as the expression level of protein C confirmed that the sepsis resulted in serious pathological damage, while all of these indices could be reversed by JH decoction and antibiotics. The diversity and abundance of intestinal flora decreased in CLP mice, and the decrements aggravated after antibiotic treatment while can be recovered by JH decoction treatment. The abundance of anti-inflammatory Ruminococcaceae increased after JH decoction treatment, indicating that JH decoction could ameliorate pathology associated with sepsis in CLP model via modulating the intestinal flora. This study demonstrates that JH decoction could treat sepsis clinically without obvious adverse effects on gut microbiota.

Pseudomonas aeruginosa breaches respiratory epithelia through goblet cell invasion in a microtissue model

Pseudomonas aeruginosa, a leading cause of severe hospital-acquired pneumonia, causes infections with up to 50% mortality rates in mechanically ventilated patients. Despite some knowledge of virulence factors involved, it remains unclear how P. aeruginosa disseminates on mucosal surfaces and invades the tissue barrier. Using infection of human respiratory epithelium organoids, here we observed that P. aeruginosa colonization of apical surfaces is promoted by cyclic di-GMP-dependent asymmetric division. Infection with mutant strains revealed that Type 6 Secretion System activities promote preferential invasion of goblet cells. Type 3 Secretion System activity by intracellular bacteria induced goblet cell death and expulsion, leading to epithelial rupture which increased bacterial translocation and dissemination to the basolateral epithelium. These findings show that under physiological conditions, P. aeruginosa uses coordinated activity of a specific combination of virulence factors and behaviours to invade goblet cells and breach the epithelial barrier from within, revealing mechanistic insight into lung infection dynamics.

LncRNA H19 acts as miR-301a-3p sponge to alleviate lung injury in mice with sepsis by regulating Adcy1

BACKGROUND

The abnormal expression of long non-coding RNA (lncRNA) is closely related to disease progression. However, the role and mechanism of lncRNA H19 (lncH19) in sepsis-induced lung injury remain to be elucidated.

METHODS

Cercal ligation and puncture (CLP) mice models and lipopolysaccharide (LPS)-induced cell injury model were used to construct sepsis-induced lung injury in vivo and in vitro. The expression of lncH19, microRNA (miR)-301a-3p and adenylate cyclase 1 (Adcy1) mRNA was assessed using quantitative real-time PCR. The concentrations of inflammatory factors were determined by ELISA assay. Cell proliferation and apoptosis were determined using cell counting kit 8 assay, EdU staining and flow cytometry. The protein expression of apoptosis markers and Adcy1 was examined by western blot analysis. Oxidative stress was assessed by detecting the contents of oxidative stress markers. The interaction between miR-301a-3p and lncH19 or Adcy1 was confirmed using RNA pull-down assay, dual-luciferase reporter assay and RIP assay.

RESULTS

LncH19 was lowly expressed in CLP mice models and LPS-induced cell injury models. Overexpressed lncH19 could alleviate CLP-induced lung injury in mice, as well as LPS-induced cell apoptosis, inflammation and oxidative stress. MiR-301a-3p could be sponged by lncH19, and its overexpression could reverse the inhibition of lncH19 on LPS-induced cell injury. Adcy1 was a target of miR-301a-3p, and its expression was upregulated by lncH19. Silencing of Adcy1 could abolish the suppressive effect of miR-301a-3p inhibitor on LPS-induced cell injury.

CONCLUSION

LncH19 might inhibit sepsis-induced lung injury through acting as a sponge of miR-301a-3p to upregulate Adcy1.Highlights:LncH19 overexpression relieves CLP-induced lung injury and LPS-induced cell injury.LncH19 directly sponges miR-301a-3p.MiR-301a-3p targets Adcy1.

The impact of maternal protein restriction during perinatal life on the response to a septic insult in adult rats

Although abundant evidence exists that adverse events during pregnancy lead to chronic conditions, there is limited information on the impact of acute insults such as sepsis. This study tested the hypothesis that impaired fetal development leads to altered organ responses to a septic insult in both male and female adult offspring. Fetal growth restricted (FGR) rats were generated using a maternal protein-restricted diet. Male and female FGR and control diet rats were housed until 150-160 d of age when they were exposed either a saline (control) or a fecal slurry intraperitoneal (Sepsis) injection. After 6 h, livers and lungs were analyzed for inflammation and, additionally, the amounts and function of pulmonary surfactant were measured. The results showed increases in the steady-state mRNA levels of inflammatory cytokines in the liver in response to the septic insult in both males and females; these responses were not different between FGR and control diet groups. In the lungs, cytokines were not detectable in any of the experimental groups. A significant decrease in the relative amount of surfactant was observed in male FGR offspring, but this was not observed in control males or in female animals. Overall, it is concluded that FGR induced by maternal protein restriction does not impact liver and lung inflammatory response to sepsis in either male or female adult rats. An altered septic response in male FGR offspring with respect to surfactant may imply a contribution to lung dysfunction.

Sini decoction ameliorates interrelated lung injury in septic mice by modulating the composition of gut microbiota

Our work used cecal ligation and puncture (CLP) mice model and 16S rDNA sequencing to explore whether the therapeutic mechanism of Sini Decoction (SND) on sepsis was related to the intestinal flora currently of concern. Twenty-four hours after surgery, tissues and serum from three groups (Control, CLP and CLP + SND) were collected for further analysis and colon contents were isolated for 16S rDNA analysis. Mortality, histological examination and inflammatory cytokines levels confirmed that the sepsis model was induced successfully and resulted in serious pathological damage, while all of these could be reversed by SND. In intestinal flora analysis, the microbial richness and abundance were recovered after SND treatment. Furthermore, at the phylum level, the abundance of Proteobacteria showed drastic increase after CLP. Similarly, CLP surgery significantly disrupted the balance of intestinal flora, with a huge increase of Escherichia-Shigella, a Gram-negative genus that might release lipopolysaccharide (LPS) and other genera. And these shifts could be defused by SND, indicating its function of regulating gut microbiota. This study demonstrates that SND could ameliorate the symptoms and pathology associated with sepsis in CLP model via modulating the flora in intestinal tract, which enriches a possible mechanism of SND's therapeutic effect.

A clinical and pathological description of 320 cases of naturally acquired Babesia rossi infection in dogs

Babesia rossi causes the most severe clinical disease in dogs of all the babesia parasites. We included 320 naturally-infected dogs that presented for care at the Onderstepoort Veterinary Academic Hospital between 2006 and 2016. All dogs had mono-infections confirmed by multiplex PCR. The data allowed more accurate clinical classification of the disease and identified parameters that were associated with disease severity and death. Odds ratios for dying were significant (P < 0.05) for increased band neutrophil count, collapse at presentation; presence of cerebral signs; hypoglycaemia; hyperlactatemia; high urea, high creatinine; hyperbilirubinaemia; hypercortisolaemia; and hypothyroxinaemia. Joint component analysis confirmed that the variables with significant odds ratios grouped together with death. Yet, multivariate logistic regression was unable to identify a group of significant independent predictors of death. Receiver Operator Characteristic curves indicated that low total thyroid hormone, high bilirubin, high serum urea and high cortisol concentrations were the variables with the highest sensitivity and specificity for death. These data provide both the clinician and researcher with a set of easily-measured laboratory and clinical assessments to classify cases into those that are uncomplicated and those that are complicated. The disease is complex and multisystemic and probably involves mechanisms more proximal in the pathogenesis than those that have been evaluated.

Pulmonary arterial hypertension and sepsis: prothrombotic profile and inflammation can changes pulmonary mechanics?

Pulmonary arterial hypertension (PAH) is associated to cellular and structural alterations of lung vasculature. Endothelial dysfunction promotes vasoconstriction, smooth muscle hypertrophy, intimal proliferation, angioproliferative plexiform lesions, and in situ thrombosis increasing pulmonary vascular resistance and arterial stiffness. Indeed, an inflammatory component has been defined in PAH on the last years. Sepsis is a systemic complex syndrome, of infectious origin. The presence of inflammation is well established in this condition and it is also considered a risk factor for acute lung injury. Thrombotic events play important role in sepsis pathophysiology. The association between PAH and sepsis potentiate the metabolic oxygen consumption/offer imbalance, with very high mortality risk. Furthermore, it is possible that the association of these two conditions should intensify thrombotic events on pulmonary microcirculation, reducing area of pulmonary vascular bed available for blood flow. For the other side, an inflammation synergism observed on these two conditions should increase the respiratory system impedance.

Lung-derived macrophage migration inhibitory factor in sepsis induces cardio-circulatory depression

BACKGROUND

Acute lung injury is common during sepsis. Whereas gaseous exchange often can be supported adequately, death results frequently from cardio-circulatory depression, the mechanisms of which remain unclear. The aim of this study was to determine whether cardio-circulatory dysfunction during sepsis results from release of macrophage migration inhibitory factor (MIF) by the lung.

METHODS

Polymicrobial sepsis was induced by cecal ligation and puncture (CLP) in adult Sprague-Dawley rats. Macrophage MIF was measured in the plasma sampled from the right ventricle (pre-lung) and left atrium (post-lung).

RESULTS

The concentration of macrophage MIF in each of the post-lung samples was higher than in the corresponding pre-lung sample at 6 h (p = 0.015; paired t-test), 20 h (p = 0.008), and 30 h (p = 0.026) after the induction of sepsis. Next, rats that underwent CLP were treated with either saline (control) or our specific MIF inhibitor, (S, R )-3-(4-hydroxyphenyl)-4,5-dehydro-5-isoxazole acetic acid methyl ester (ISO-1). Echocardiography revealed that ISO-1 significantly improved the left ventricular end-diastolic volume index (p = 0.02), stroke volume index (p = 0.01), and cardiac index (p = 0.02) at 30 h after the induction of sepsis.

CONCLUSIONS

The lung appears to release significant amounts of macrophage MIF into the systemic circulation during late sepsis. Inhibition of MIF in a clinically relevant time frame blocked polymicrobial peritonitis-induced cardio-circulatory dysfunction. Inhibition of MIF may be a useful strategy to prevent cardio-circulatory deterioration associated with late sepsis.

Tumor Suppressor CYLD Regulates Acute Lung Injury in Lethal Streptococcus pneumoniae Infections

Streptococcus pneumoniae (S. pneumoniae) causes high early mortality in pneumococcal pneumonia, which is characterized by acute lung injury (ALI). The molecular mechanisms underlying ALI and the high early mortality remain unknown. Despite recent studies that identify deubiquitinating enzyme cylindromatosis (CYLD) as a key regulator for T cell development, tumor cell proliferation, and NF-kappaB transcription factor signaling, its role in regulating bacteria-induced lethality, however, is unknown. Here, we showed that CYLD deficiency protected mice from S. pneumoniae pneumolysin (PLY)-induced ALI and lethality. CYLD was highly induced by PLY, and it inhibited MKK3-p38 kinase-dependent expression of plasminogen activator inhibitor-1 (PAI-1) in lung, thereby potentiating ALI and mortality. Thus, CYLD is detrimental for host survival, thereby indicating a mechanism underlying the high early mortality of pneumococcal pneumonia.