Effect of TLR4/MyD88 signaling pathway on sepsis-associated acute respiratory distress syndrome in rats, via regulation of macrophage activation and inflammatory response

Retracted article: Protective effects of ulinastatin on rats with acute lung injury induced by lipopolysaccharide

Qitong Lu, Zhiyong Liu, Wei He and Xin Chu. Protective effects of ulinastatin on rats with acute lung injury induced by lipopolysaccharide. Bioengineered. 2021 Oct. doi: 10.1080/21655979.2021.1987083.Since publication, significant concerns have been raised about the compliance with ethical policies for human research and the integrity of the data reported in the article.When approached for an explanation, the authors provided some original data but were not able to provide all the necessary supporting information. As verifying the validity of published work is core to the scholarly record's integrity, we are retracting the article. All authors listed in this publication have been informed.We have been informed in our decision-making by our editorial policies and the COPE guidelines. The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as 'Retracted.'

Interplay of TLR4 and SARS-CoV-2: Unveiling the Complex Mechanisms of Inflammation and Severity in COVID-19 Infections

The late 2019 emergence of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19, caused profound and unprecedented disruption to the global socio-economic structure, negatively affecting millions of lives worldwide. A typical hallmark of severe COVID-19 is hyper inflammation due to aberrant cytokine release (cytokine storm) by innate immune cells. Recent studies have revealed that SARS-CoV-2, through its spike (S) protein, can activate the body's innate immune cells via Toll-Like Receptors (TLRs), particularly TLR4. In silico studies have demonstrated that the S protein binds with high affinity to TLR4, triggering downstream signaling processes that result in pro-inflammatory cytokine release. Compared to other TLRs, such as TLR2, TLR4 plays a more significant role in initiating and sustaining the inflammatory response associated with severe COVID-19. Furthermore, interactions between the virus and target cells can enhance the cellular expression of TLR4, making cells more susceptible to viral interactions and subsequent inflammation. This increased expression of TLR4 upon viral entry creates a feedback loop, where heightened TLR4 levels lead to amplified inflammatory responses, contributing to the severity of the disease. Additionally, TLR4's potent activation of inflammatory pathways sets it apart from other TLRs, underscoring its pivotal role in the pathogenesis of COVID-19. In this review, we thoroughly explore the multitude of regulatory signaling pathways that SARS-CoV-2 employs to incite inflammation. We specifically focus on the critical impact of TLR4 activation compared to other TLRs, highlighting how TLR4's interactions with the viral S protein can exacerbate the severity of COVID-19. By delving into the mechanisms of TLR4-mediated inflammation, we aim to shed light on potential therapeutic targets that could mitigate the inflammatory damage caused by severe COVID-19. Understanding the unique role of TLR4 in the context of SARS-CoV-2 infection could pave the way for novel treatment strategies that specifically inhibit this receptor's activity, thereby reducing the overall disease burden and improving patient outcomes.

Preliminary study on the protective effect of remazolam against sepsis-induced acute respiratory distress syndrome (ARDS)

Background

Sepsis can disrupt immune regulation and lead to acute respiratory distress syndrome (ARDS) frequently. Remazolam, a fast-acting hypnotic drug with superior qualities compared to other drugs, was investigated for its potential protective effects against sepsis-induced ARDS.

Methods

Forty Sprague-Dawley rats were randomly divided into four groups, including the sepsis + saline group, sham operation + saline group, sham operation + remazolam group and the sepsis + remazolam group. Lung tissues of rats were extracted for HE staining to assess lung damage, and the wet weight to dry weight (W/D) ratio was calculated. The levels of proinflammatory factors, anti-inflammatory factors, CD4+ and CD8+ T cells in peripheral blood, MDA, MPO, and ATP in the lung tissue were measured by using ELISA. Western blotting was performed to determine the protein expression of HMGB1 in lung tissues.

Results

In comparison to the sham operation + saline and sham operation + remazolam groups, the sepsis + saline group exhibited significantly higher values for W/D ratio, lung damage score, IL-1β, IL-6, TNF-α, PCT, CRP, MDP and MPO, while exhibiting lower levels of CD4+ and CD8+ T lymphocytes, PaO2, PCO2, and ATP. The rats in the sepsis + saline group displayed ruptured alveolar walls and evident interstitial lung edema. However, the rats in the sepsis + remazolam group showed improved alveolar structure. Furthermore, the HMGB1 protein expression in the sepsis + remazolam group was lower than the sepsis + saline group.

Conclusion

Remazolam can alleviate the inflammatory response in infected rats, thereby alleviating lung injury and improving immune function, which may be attributed to the reduction in HMGB1 protein expression.

Plasticity and crosstalk of mesenchymal stem cells and macrophages in immunomodulation in sepsis

Sepsis is a multisystem disease characterized by dysregulation of the host immune response to infection. Immune response kinetics play a crucial role in the pathogenesis and progression of sepsis. Macrophages, which are known for their heterogeneity and plasticity, actively participate in the immune response during sepsis. These cells are influenced by the ever-changing immune microenvironment and exhibit two-sided immune regulation. Recently, the immunomodulatory function of mesenchymal stem cells (MSCs) in sepsis has garnered significant attention. The immune microenvironment can profoundly impact MSCs, prompting them to exhibit dual immunomodulatory functions akin to a double-edged sword. This discovery holds great importance for understanding sepsis progression and devising effective treatment strategies. Importantly, there is a close interrelationship between macrophages and MSCs, characterized by the fact that during sepsis, these two cell types interact and cooperate to regulate inflammatory processes. This review summarizes the plasticity of macrophages and MSCs within the immune microenvironment during sepsis, as well as the intricate crosstalk between them. This remains an important concern for the future use of these cells for immunomodulatory treatments in the clinic.

Role of DCLK1/Hippo pathway in type II alveolar epithelial cells differentiation in acute respiratory distress syndrome

BACKGROUND

Delay in type II alveolar epithelial cell (AECII) regeneration has been linked to higher mortality in patients with acute respiratory distress syndrome (ARDS). However, the interaction between Doublecortin-like kinase 1 (DCLK1) and the Hippo signaling pathway in ARDS-associated AECII differentiation remains unclear. Therefore, the objective of this study was to understand the role of the DCLK1/Hippo pathway in mediating AECII differentiation in ARDS.

MATERIALS AND METHODS

AECII MLE-12 cells were exposed to 0, 0.1, or 1 μg/mL of lipopolysaccharide (LPS) for 6 and 12 h. In the mouse model, C57BL/6JNarl mice were intratracheally (i.t.) injected with 0 (control) or 5 mg/kg LPS and were euthanized for lung collection on days 3 and 7.

RESULTS

We found that LPS induced AECII markers of differentiation by reducing surfactant protein C (SPC) and p53 while increasing T1α (podoplanin) and E-cadherin at 12 h. Concurrently, nuclear YAP dynamic regulation and increased TAZ levels were observed in LPS-exposed AECII within 12 h. Inhibition of YAP consistently decreased cell levels of SPC, claudin 4 (CLDN-4), galectin 3 (LGALS-3), and p53 while increasing transepithelial electrical resistance (TEER) at 6 h. Furthermore, DCLK1 expression was reduced in isolated human AECII of ARDS, consistent with the results in LPS-exposed AECII at 6 h and mouse SPC-positive (SPC+) cells after 3-day LPS exposure. We observed that downregulated DCLK1 increased p-YAP/YAP, while DCLK1 overexpression slightly reduced p-YAP/YAP, indicating an association between DCLK1 and Hippo-YAP pathway.

CONCLUSIONS

We conclude that DCLK1-mediated Hippo signaling components of YAP/TAZ regulated markers of AECII-to-AECI differentiation in an LPS-induced ARDS model.

Acute respiratory distress syndrome heterogeneity and the septic ARDS subgroup

Acute respiratory distress syndrome (ARDS) is an acute diffuse inflammatory lung injury characterized by the damage of alveolar epithelial cells and pulmonary capillary endothelial cells. It is mainly manifested by non-cardiogenic pulmonary edema, resulting from intrapulmonary and extrapulmonary risk factors. ARDS is often accompanied by immune system disturbance, both locally in the lungs and systemically. As a common heterogeneous disease in critical care medicine, researchers are often faced with the failure of clinical trials. Latent class analysis had been used to compensate for poor outcomes and found that targeted treatment after subgrouping contribute to ARDS therapy. The subphenotype of ARDS caused by sepsis has garnered attention due to its refractory nature and detrimental consequences. Sepsis stands as the most predominant extrapulmonary cause of ARDS, accounting for approximately 32% of ARDS cases. Studies indicate that sepsis-induced ARDS tends to be more severe than ARDS caused by other factors, leading to poorer prognosis and higher mortality rate. This comprehensive review delves into the immunological mechanisms of sepsis-ARDS, the heterogeneity of ARDS and existing research on targeted treatments, aiming to providing mechanism understanding and exploring ideas for accurate treatment of ARDS or sepsis-ARDS.

Morphofunctional Characteristics of Lung Macrophages in Rats with Acute Respiratory Distress Syndrome

A comprehensive morphofunctional study of the lungs and alveolar macrophages was carried out in Sprague-Dawley rats with acute respiratory distress syndrome (n=10) induced by intratracheal administration of E. coli LPS 0111:B4 in a dose of 15 mg/kg. On the first day after LPS administration, bronchopneumonia was observed in the lungs, the number of macrophages of the bone marrow origin and the number of M1 macrophages with the proinflammatory phenotype in the bronchoalveolar lavage increased, the expression of proinflammatory cytokines increased and the expression of anti-inflammatory cytokines decreased, which was accompanied by an increase in LPS and C-reactive protein in the blood serum. The revealed changes correspond to the development of acute respiratory distress syndrome in humans, and the decrease in the number of macrophages in the lungs and their predominant polarization to the M1-proinflammatory phenotype substantiate the use of cell therapy with reprogrammed M2 macrophages.

Liraglutide pretreatment attenuates sepsis-induced acute lung injury

There are no effective targeted therapies to treat acute respiratory distress syndrome (ARDS). Recently, the commonly used diabetes and obesity medications, glucagon-like peptide-1 (GLP-1) receptor agonists, have been found to have anti-inflammatory properties. We, therefore, hypothesized that liraglutide pretreatment would attenuate murine sepsis-induced acute lung injury (ALI). We used a two-hit model of ALI (sepsis+hyperoxia). Sepsis was induced by intraperitoneal injection of cecal slurry (CS; 2.4 mg/g) or 5% dextrose (control) followed by hyperoxia [HO; fraction of inspired oxygen ([Formula: see text]) = 0.95] or room air (control; [Formula: see text] = 0.21). Mice were pretreated twice daily with subcutaneous injections of liraglutide (0.1 mg/kg) or saline for 3 days before initiation of CS+HO. At 24-h post CS+HO, physiological dysfunction was measured by weight loss, severity of illness score, and survival. Animals were euthanized, and bronchoalveolar lavage (BAL) fluid, lung, and spleen tissues were collected. Bacterial burden was assessed in the lung and spleen. Lung inflammation was assessed by BAL inflammatory cell numbers, cytokine concentrations, lung tissue myeloperoxidase activity, and cytokine expression. Disruption of the alveolar-capillary barrier was measured by lung wet-to-dry weight ratios, BAL protein, and epithelial injury markers (receptor for advanced glycation end products and sulfated glycosaminoglycans). Histological evidence of lung injury was quantified using a five-point score with four parameters: inflammation, edema, septal thickening, and red blood cells (RBCs) in the alveolar space. Compared with saline treatment, liraglutide improved sepsis-induced physiological dysfunction and reduced lung inflammation, alveolar-capillary barrier disruption, and lung injury. GLP-1 receptor activation may hold promise as a novel treatment strategy for sepsis-induced ARDS. Additional studies are needed to better elucidate its mechanism of action.NEW & NOTEWORTHY In this study, pretreatment with liraglutide, a commonly used diabetes medication and glucagon-like peptide-1 (GLP-1) receptor agonist, attenuated sepsis-induced acute lung injury in a two-hit mouse model (sepsis + hyperoxia). Septic mice who received the drug were less sick, lived longer, and displayed reduced lung inflammation, edema, and injury. These therapeutic effects were not dependent on weight loss. GLP-1 receptor activation may hold promise as a new treatment strategy for sepsis-induced acute respiratory distress syndrome.

Remifentanil attenuates endoplasmic reticulum stress and inflammatory injury in LPS-induced damage in HK-2 cells

Renal injury is a fatal complication in critically ill patients with sepsis. As an ultrashort-acting synthetic opioid derivative, remifentanil has been reported to mitigate renal injury and sepsis. Nevertheless, whether remifentanil also suppresses sepsis-triggered renal injury is uncertain. The aim of this study was to investigate the effect of remifentanil on endoplasmic reticulum stress (ERS) and inflammatory response in an in vitro lipopolysaccharide (LPS)-stimulated renal tubular epithelial cell (HK-2) model and its mechanism. The viability of HK-2 cells with the absence or presence of LPS treatment was surveyed by cell counting kit-8 assay. Under the condition of LPS treatment, apoptosis was appraised by TUNEL assay and western blot. Levels of inflammatory factors were estimated though corresponding kits. Western blot tested the expression of toll-like receptor 4 (TLR4)/nuclear factor-kappaB (NF-κB) signaling-associated proteins. Also, the expression of ERS-related proteins was detected by western blot. Further, ERS inducer tunicamycin (TM) was added and the aforementioned experiments were conducted again. The results underlined the protective effects of remifentanil on LPS-evoked viability injury, inflammation, activation of TLR4/NF-κB signaling and ERS in HK-2 cells. Moreover, the impacts of remifentanil on the biological events of LPS-insulted HK-2 cells were all reversed by TM administration. To conclude, remifentanil might have a remarkable ameliorative effect on sepsis-induced renal injury, which implied the potential of remifentanil-based drug therapy in sepsis-induced renal injury.

The effect of antidepressants on the severity of COVID-19 in hospitalized patients: A systematic review and meta-analysis

INTRODUCTION

Clinical Depression and the subsequent low immunity is a comorbidity that can act as a risk factor for the severity of COVID-19 cases. Antidepressants such as Selective serotonin reuptake inhibitor and Serotonin-norepinephrine reuptake inhibitors are associated with immune-modulatory effects, which dismiss inflammatory responses and reduce lung tissue damage. The current systematic review and meta-analysis aims to evaluate the effect of antidepressant drugs on the prognosis and severity of COVID-19 in hospitalized patients.

METHODS

A systematic search was carried out in PubMed/Medline, EMBASE, and Scopus up to June 14, 2022. The following keywords were used: "COVID-19", "SARS-CoV-2", "2019-nCoV", "SSRI", "SNRI", "TCA", "MAOI", and "Antidepressant". A fixed or random-effect model assessed the pooled risk ratio (RR) with 95% CI. We considered P < 0.05 as statistically significant for publication bias. Data were analyzed by Comprehensive Meta-Analysis software, Version 2.0 (Biostat, Englewood, NJ).

RESULTS

Fourteen studies were included in our systematic review. Five of them were experimental with 2350, and nine of them were observational with 290,950 participants. Eight out of fourteen articles revealed the effect of antidepressants on reducing the severity of COVID-19. Selective serotonin reuptake inhibitors drugs, including Fluvoxamine, Escitalopram, Fluoxetine, and Paroxetine, and among the Serotonin-norepinephrine inhibitors medications Venlafaxine, are reasonably associated with reduced risk of intubation or death. Five studies showed no significant effect, and only one high risk of bias article showed the negative effect of antidepressants on the prognosis of Covid-19. The meta-analysis of clinical trials showed that fluvoxamine could significantly decrease the severity outcomes of COVID-19 (RR: 0.763; 95% CI: 0.602-0.966, I2: 0.0).

FINDINGS

Most evidence supports that the use of antidepressant medications, mainly Fluvoxamine, may decrease the severity and improve the outcome in hospitalized patients with SARS-CoV-2. Some studies showed contradictory findings regarding the effects of antidepressants on the severity of COVID-19. Further clinical trials should be conducted to clarify the effects of antidepressants on the severity of COVID-19.

Plasma Proprotein Convertase Subtilisin/kexin Type 9 (PCSK9) in the Acute Respiratory Distress Syndrome

Background

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a serine protease that is a mediator of the immune response to sepsis. PCSK9 is also highly expressed in pneumocytes and pulmonary endothelial cells. We hypothesized that serum PCSK9 levels would be associated with death and ICU outcomes in patients with ARDS.

Methods

Using data and plasma samples from the NIH BioLINCC data repository, we assembled a cohort of 1,577 patients with the acute respiratory distress syndrome (ARDS) enrolled in two previously completed clinical trials, EDEN and SAILS. We measured PCSK9 levels in plasma within 24 h of intubation using commercially available ELISA kits (R&D Systems). We assessed the association of PCSK9 with mortality using Cox proportional hazard models. We also assessed clinical factors associated with PCSK9 level and the association of PCSK9 with the number of days free of mechanical ventilation and days free of ICU care.

Results

In 1,577 ARDS patients, median age was 53 years (IQR 42–65 years) and median APACHE III score 91 (72–111) connoting moderate critical illness. PCSK9 levels were 339.3 ng/mL (IQR 248.0–481.0). In multivariable models, race, cause of ARDS, body mass index, pre-existing liver disease, body temperature, sodium, white blood cell count and platelet count were associated with PCSK9 level. Presence of sepsis, use of vasopressors and ventilator parameters were not associated with PCSK9 level. PCSK9 levels were not associated with in-hospital mortality (HR per IQR 0.96, 95% CI 0.84–1.08, P = 0.47). Higher PCSK9 levels were associated with fewer ICU and ventilator free days.

Conclusions

Plasma PCSK9 is not associated with mortality in ARDS, however higher PCSK9 levels are associated with secondary outcomes of fewer ICU free and ventilator free days. Clinical factors associated with PCSK9 in ARDS are largely unmodifiable. Further research to define the mechanism of this association is warranted.

Comparison of COVID-19 characteristics in Egyptian patients according to their Toll-Like Receptor-4 (Asp299Gly) polymorphism

BACKGROUND

Toll-like receptor (TLR)-4 plays a vital role in recognizing viral particles, activating the innate immune system, and producing pro-inflammatory cytokines.

OBJECTIVES

This cross-sectional study aimed to compare COVID-19 severity, progression, and fate according to TLR-4 (Asp299Gly) polymorphism in Egyptian patients.

METHODS

A total of 145 COVID-19 patients were included in this study. TLR-4 (Asp299Gly) genotyping was done using the PCR restriction fragment length polymorphism (PCR-RFLP) approach.

RESULTS

The most commonly encountered TLR-4 genotype in relation to the amino acid at position 299 was the wild-type AA (73.1%); meanwhile, the homozygous mutant GG genotype (8.3%) was the least encountered. At hospital admission, 85.8% of the AA group had free (with no ground glass opacities) chest computed tomography (CT) examination, and 16.0% were asymptomatic. On the other hand, of the AG and GG groups, 81.5% and 83.3%, respectively showed bilateral ground-glass opacities in chest CT, as well as 25.9% and 75.0%, respectively were dyspneic. Values of the total leucocytic count, C-reactive protein (CRP), ferritin, and D dimer increased in the AA<AG<GG sequence. In contrast, hemoglobin values and the absolute lymphocyte counts decreased in the AA>AG>GG sequence. ICU admission (83.3%) and in-hospital death (33.3%) rates were significantly higher in the GG group.

CONCLUSIONS

In COVID-19 patients, the TLR-4 mutant G allele may be associated with a more aggressive disease course and in-hospital death. New therapeutic alternatives could be aimed at this area.

Severe Acute Respiratory Syndrome Coronavirus 2: The Role of the Main Components of the Innate Immune System

At the end of December 2019, the COVID-19 pandemic began in Wuhan of China. COVID-19 affects different people with a wide spectrum of clinical manifestations, ranging from asymptomatic with recovery without hospitalization up to a severe acute respiratory syndrome (SARS). The innate and adaptive immunity appears responsible for the defense against the virus and recovery from the disease. The innate immune system, as the first line of defense, is essential for the detection of virus and subsequent activation of acquired immunity. The innate immune response is carried out by sentinel cells such as monocytes/macrophages and dendritic cells and by receptors known as pattern recognition receptors (PRR). These receptors can recognize various components of the virus, which lead to intracellular signaling and subsequently the synthesis of various cytokines. These cytokines then recruit other immune cells, activate adaptive immune responses, and inhibit viral spreading. The most common receptors include Toll-like receptors, C-type lectin receptors, and RIG-I like receptors. This review describes the current knowledge about the interplay between innate immune responses and SARS-CoV-2 with a focus on the innate immune cells and the role of their receptors in viral RNA recognition, as well as their mechanisms for recognizing SARS-CoV-2.

Progranulin signaling in sepsis, community-acquired bacterial pneumonia and COVID-19: a comparative, observational study

Background

Progranulin is a widely expressed pleiotropic growth factor with a central regulatory effect during the early immune response in sepsis. Progranulin signaling has not been systematically studied and compared between sepsis, community-acquired pneumonia (CAP), COVID-19 pneumonia and a sterile systemic inflammatory response (SIRS). We delineated molecular networks of progranulin signaling by next-generation sequencing (NGS), determined progranulin plasma concentrations and quantified the diagnostic performance of progranulin to differentiate between the above-mentioned disorders using the established biomarkers procalcitonin (PCT), interleukin-6 (IL-6) and C-reactive protein (CRP) for comparison.

Methods

The diagnostic performance of progranulin was operationalized by calculating AUC and ROC statistics for progranulin and established biomarkers in 241 patients with sepsis, 182 patients with SIRS, 53 patients with CAP, 22 patients with COVID-19 pneumonia and 53 healthy volunteers. miRNAs and mRNAs in blood cells from sepsis patients (n = 7) were characterized by NGS and validated by RT-qPCR in an independent cohort (n = 39) to identify canonical gene networks associated with upregulated progranulin at sepsis onset.

Results

Plasma concentrations of progranulin (ELISA) in patients with sepsis were 57.5 (42.8–84.9, Q25–Q75) ng/ml and significantly higher than in CAP (38.0, 33.5–41.0 ng/ml, p < 0.001), SIRS (29.0, 25.0–35.0 ng/ml, p < 0.001) and the healthy state (28.7, 25.5–31.7 ng/ml, p < 0.001). Patients with COVID-19 had significantly higher progranulin concentrations than patients with CAP (67.6, 56.6–96.0 vs. 38.0, 33.5–41.0 ng/ml, p < 0.001). The diagnostic performance of progranulin for the differentiation between sepsis vs. SIRS (n = 423) was comparable to that of procalcitonin. AUC was 0.90 (95% CI = 0.87–0.93) for progranulin and 0.92 (CI = 0.88–0.96, p = 0.323) for procalcitonin. Progranulin showed high discriminative power to differentiate bacterial CAP from COVID-19 (sensitivity 0.91, specificity 0.94, AUC 0.91 (CI = 0.8–1.0) and performed significantly better than PCT, IL-6 and CRP. NGS and partial RT-qPCR confirmation revealed a transcriptomic network of immune cells with upregulated progranulin and sortilin transcripts as well as toll-like-receptor 4 and tumor-protein 53, regulated by miR-16 and others.

Conclusions

Progranulin signaling is elevated during the early antimicrobial response in sepsis and differs significantly between sepsis, CAP, COVID-19 and SIRS. This suggests that progranulin may serve as a novel indicator for the differentiation between these disorders.

Trial registration: Clinicaltrials.gov registration number NCT03280576 Registered November 19, 2015.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40635-021-00406-7.

Increased TLR/MyD88 signaling in patients with obesity: is there a link to COVID-19 disease severity?

COVID-19 is a pandemic disease caused by a coronavirus, designed as SARS CoV-2, whose clinical presentation is widely variable, with most patients having mild or no symptoms, but others developing a malign disease with multi-organ failure and even death. Accumulating data from different populations have shown that obesity is a risk factor for a severe evolution of the disease, however, the mechanisms that explain this association are not clearly understood. An ominous evolution of COVID-19 has been attributed to an exacerbated inflammatory response, designed as "cytokine storm" with augmented production of cytokines/chemokines through the activation of toll-like receptors (TLR) by pathogen-associated molecular patterns, that triggers an inflammatory downstream response, mediated in part by the adaptor molecule, myeloid differentiation factor 88 (MyD88). Previous studies have reported an increased expression of MyD88 and TLRs in people with obesity, mainly in those with metabolic complications. Therefore, we hypothesize, that an underlying increased Myd88/TLR signaling may predispose to patients with obesity to develop an exaggerated and dangerous inflammatory reaction against SARS CoV-2 infection, explaining at least in part, the higher severity of COVID-19. In addition, MyD88/TLR signaling in people with obesity could have a role in the development of several chronic diseases.

From sepsis to acute respiratory distress syndrome (ARDS): emerging preventive strategies based on molecular and genetic researches

A healthy body activates the immune response to target invading pathogens (i.e. viruses, bacteria, fungi, and parasites) and avoid further systemic infection. The activation of immunological mechanisms includes several components of the immune system, such as innate and acquired immunity. Once any component of the immune response to infections is aberrantly altered or dysregulated, resulting in a failure to clear infection, sepsis will develop through a pro-inflammatory immunological mechanism. Furthermore, the severe inflammatory responses induced by sepsis also increase vascular permeability, leading to acute pulmonary edema and resulting in acute respiratory distress syndrome (ARDS). Apparently, potential for improvement exists in the management of the transition from sepsis to ARDS; thus, this article presents an exhaustive review that highlights the previously unrecognized relationship between sepsis and ARDS and suggests a direction for future therapeutic developments, including plasma and genetic pre-diagnostic strategies and interference with proinflammatory signaling.

Green propolis extract attenuates acute kidney injury and lung injury in a rat model of sepsis

Sepsis is the leading cause of acute kidney injury (AKI) and lung injury worldwide. Despite therapeutic advances, sepsis continues to be associated with high mortality. Because Brazilian green propolis (GP) has promising anti-inflammatory, antioxidant, and immunomodulatory properties, we hypothesized that it would protect kidneys and lungs in rats induced to sepsis by cecal ligation and puncture (CLP). Male Wistar rats were divided into groups-control (sham-operated); CLP (CLP only); and CLP + GP (CLP and treatment with GP at 6 h thereafter)-all receiving volume expansion and antibiotic therapy at 6 h after the procedures. By 24 h after the procedures, treatment with GP improved survival, attenuated sepsis-induced AKI, and restored renal tubular function. Whole-blood levels of reduced glutathione were higher in the CLP + GP group. Sepsis upregulated the Toll-like receptor 4/nuclear factor-kappa B axis in lung and renal tissues, as well as increasing inflammatory cytokine levels and macrophage infiltration; all of those effects were attenuated by GP. Treatment with GP decreased the numbers of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling-positive cells in renal and lung tissue, as well as protecting the morphology of the renal mitochondria. Our data open the prospect for clinical trials of the use of GP in sepsis.

Identification of Genes with Altered Methylation and Its Role in Early Diagnosis of Sepsis-Induced Acute Respiratory Distress Syndrome

Purpose

Early diagnosis of sepsis-induced acute respiratory distress syndrome (ARDS) is critical for effective treatment. We aimed to identify early stage biomarkers.

Materials and Methods

Differentially expressed genes were identified in whole blood samples from patients with sepsis or ARDS based on the Gene Expression Omnibus (GEO) datasets GSE32707, GSE54514 and GSE10361. Functional enrichment analysis explored the biological characteristics of differentially expressed genes. Genes with high functional connectivity based on a protein-protein interaction network were marked as hub genes, which were validated using the GEO dataset GSE76293, and a gene set variation analysis index (GSVA) was assigned. Diagnostic and predictive ability of the hub genes were assessed by receiver operating characteristic (ROC) curve analysis. DNA methylation levels of hub genes were quantified using the GEO dataset GSE67530.

Results

Forty-one differentially expressed genes were shared between sepsis-specific and ARDS-specific datasets. MAP2K2 and IRF7 functional activity was highly connected in sepsis-induced ARDS. Hub genes included RETN, MVP, DEFA4, CTSG, AZU1, FMNL1, RBBP7, POLD4, RIN3, IRF7. ROC curve analysis of the hub gene GSVA index showed good diagnostic ability in sepsis or ARDS. Among genes related to sepsis-induced ARDS, 17 were differentially methylated. Principal component analysis and heatmaps indicated that gene methylation patterns differed significantly between ARDS patients and controls.

Conclusion

We identified a genetic profile specific to early-stage sepsis-induced ARDS. The abnormal expression of these genes may be caused by hypomethylation, which may serve as a biomarker for early diagnosis of ARDS.

Transcription factor-mediated signaling pathways' contribution to the pathology of acute lung injury and acute respiratory distress syndrome

The 2019 novel coronavirus (2019-nCoV) is still spreading rapidly around the world, and one cause of lethality for patients infected with 2019-nCoV is acute respiratory distress syndrome (ARDS). ARDS is a severe syndrome of acute lung injury (ALI) that is predominantly triggered by inflammation and results in a sudden loss of, or damage to, kidney function. Emerging studies reveal that multiple transcription factor-associated signaling pathways are activated in the pathology of ALI/ARDS. Of these pathways, the activation of NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells), AP-1 (activator protein 1), IRFs (interferon regulatory factors), STATs (signal transducer and activator of transcription), Wnt/β-catenin-TCF/LEF (T-cell factor/lymphoid enhancer-binding factor), and CtBP2 (C-Terminal binding protein 2)-associated transcriptional complex contributes to ALI/ARDS pathology through diverse mechanisms, such as inducing proinflammatory cytokine levels and mediating macrophage polarization. In this review, we present an updated summary of the mechanisms underlying these signaling activations and regulations, as well as their contribution to the pathogenesis of ALI/ARDS. We aim to develop a better understanding of how ALI/ARDS occurs and improve ALI/ARDS therapy.

COVID 19: a clue from innate immunity

The recent COVID-19 pandemic has had a significant impact on our lives and has rapidly expanded to reach more than 4 million cases worldwide by May 2020. These cases are characterized by extreme variability, from a mild or asymptomatic form lasting for a few days up to severe forms of interstitial pneumonia that may require ventilatory therapy and can lead to patient death.Several hypotheses have been drawn up to understand the role of the interaction between the infectious agent and the immune system in the development of the disease and the most severe forms; the role of the cytokine storm seems important.Innate immunity, as one of the first elements of guest interaction with different infectious agents, could play an important role in the development of the cytokine storm and be responsible for boosting more severe forms. Therefore, it seems important to study also this important arm of the immune system to adequately understand the pathogenesis of the disease. Research on this topic is also needed to develop therapeutic strategies for treatment of this disease.

Fighting the Host Reaction to SARS-COv-2 in Critically Ill Patients: The Possible Contribution of Off-Label Drugs

The severe acute respiratory syndrome coronavirus 2 (SARS-COv-2) is the etiologic agent of the 2019 coronavirus disease (COVID19). The majority of infected people presents flu like symptoms and among them 15–20% develops a severe interstitial pneumonitis (IP) that may eventually evolve in acute respiratory distress syndrome (ARDS). IP is caused by the viral glycoprotein spike (S) binding to the angiotensin converting enzyme 2 (ACE2) expressed on the surface of alveolar pneumocytes. The virus is recognized by the “pattern recognition receptors” (PRR) of the immune cells that release cytokines activating more immune cells that produce a large number of pro-inflammatory cytokines, tissue factors and vasoactive peptides. Affected patients might develop the “cytokine storm syndrome,” a fulminant and fatal hypercytokinaemia with multiorgan failure. In patients infected by SARS-COv-2 increase in T-helper 2 (TH2) cytokines (IL-4 and IL10) are reported in addition to the T-helper 1 (TH1) cytokines (IL1B, IFNγ, IP10, and MCP1) previously detected in other coronavirus infections. Cytokines and other molecules involved in immune response and inflammation are conceivable therapeutic targets for IP and ARDS, improving symptoms and decreasing intensive care unit admissions. To this aim off label drugs may be used taking into consideration the window timing for immunosuppressive drugs in virus infected patients. Some off label therapeutic options and preclinical evidence drugs are herein considered.

Phosphorylated Heat Shock Protein 27 Inhibits Lipopolysaccharide-Induced Inflammation in Thp1 Cells by Promoting TLR4 Endocytosis, Ubiquitination, and Degradation

The aims of this study were to investigate the effect of Hsp27 on LPS-induced inflammation and identify the precise mechanisms about how Hsp27 regulates LPS-induced TLR4 signaling in Thp1 cells. Thp1 cells were transfected with Flag-Hsp27 or pcDNA3.1, and then treated with LPS for indicated time. TNF-α, IL-1β, and IL-6 were determined by ELISA. The protein levels of Hsp27, p-Hsp27 (Ser15, Ser78, and Ser82), and TLR4 were measured by Western blotting. In vitro study showed that over-expression of Hsp27 downregulated the release of TNF-α, IL-1β, and IL-6 and suppressed the activation of TLR4 signals after stimulated by LPS. The location of TLR4 and RAB5 was detected by confocal microscopy. Immunoprecipitation was used to determine the ubiquitination and degradation of TLR4 and interaction between Hsp27 and TLR4. Results showed that Hsp27 could promote TLR4 endocytosis and ubiquitination and degradation. Further research revealed that Hsp27 was phosphorylated after LPS, only phosphorylated Hsp27 can interact with TLR4 and inhibit the activation of TLR4 signaling, which was demonstrated by inhibition of Hsp27 phosphorylation with inhibitors or transfection of Hsp27 mutants into Thp1 cells. Phosphorylated Hsp27 reduced the release of TNF-α, IL-1β, and IL-6, and suppressed the activation of TLR4 signaling by promoting TLR4 endocytosis, ubiquitination, and degradation.

CXCR4 knockdown prevents inflammatory cytokine expression in macrophages by suppressing activation of MAPK and NF-κB signaling pathways

Background

Recent evidence has shown that C-X-C chemokine receptor type 4 (CXCR4) plays a crucial role in acute lung injury (ALI). Macrophages are key factors in the pathogenesis of ALI. The aim of this study was to investigate the role of CXCR4 in macrophages after lipopolysaccharide (LPS) stimulation and confirm that CXCR4 knockdown can inhibit inflammatory cytokines by suppressing mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signaling pathway activation.

Results

In this study, we found that CXCR4 expression in lung tissue of ALI was significantly increased using immunofluorescence. We also found that the expression of CXCR4 in macrophages sorted from bronchoalveolar lavage fluid (BALF) of ALI was obviously upregulated through RT-qPCR. After CXCR4 knockdown using siRNA, we found that the expression of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) was obviously down regulated in macrophages. Additionally, the phosphorylation of p38, Erk, and p65 was significantly decreased after CXCR4 knockdown through western blotting.

Conclusions

Taken together, the present study suggests that CXCR4 knockdown may inhibit inflammatory cytokine expression in macrophages by suppressing MAPK and NF-κB signaling pathway activation. Therefore, CXCR4 knockdown may have potential clinical value in treating ALI.

[Quercetin alleviates lipopolysaccharide-induced acute kidney injury in mice by suppressing TLR4/NF-κB pathway]

OBJECTIVE

To investigate the protective effect of quercetin against lipopolysaccharide (LPS)- induced acute kidney injury (AKI) in mice and explore its mechanism.

METHODS

Forty male BALB/c mice were randomly divided into control group (with saline treatment), 15 mg/kg LPS group, and quercetin-treated groups with intragastric quercetin treatment (once daily for 3 consecutive days) at low (25 mg/kg) and high (50 mg/kg) dose prior to 15 mg/kg LPS injection. LPS was administered by intraperitoneally injection 1 after the last gavage of quercetin. The mice were sacrificed 24 h after LPS injection for analysis of kidney pathologies, blood urea nitrogen (BUN) and creatinine levels; serum levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6 were detected by ELISA, and the expressions of Toll-like receptor-4 (TLR4), MyD88, TRAF-6 and NF-κBp65 in the kidney were detected by Western blotting.

RESULTS

Quercetin significantly lessened renal pathologies, lowered BUN and creatinine levels (P < 0.05) and inhibited TNF-α, IL-1β, and IL-6 production in mice with LPS-induced AKI (P < 0.05). Pretreatment with quercetin also significantly inhibited TLR4, MyD88, and TRAF-6 expressions and NF-κBp65 activation in the kidneys of the rats with LPS challenge (P < 0.05).

CONCLUSIONS

Quercetin pretreatment can protect mice against LPSinduced AKI by inhibiting TLR4/NF-κB signaling pathway.

Leukadherin-1-Mediated Activation of CD11b Inhibits LPS-Induced Pro-inflammatory Response in Macrophages and Protects Mice Against Endotoxic Shock by Blocking LPS-TLR4 Interaction

Dysregulation of macrophage has been demonstrated to contribute to aberrant immune responses and inflammatory diseases. CD11b, expressed on macrophages, plays a critical role in regulating pathogen recognition, phagocytosis, and cell survival. In the present study, we explored the effect of leukadherin-1 (LA1), an agonist of CD11b, on regulating LPS-induced pro-inflammatory response in macrophages and endotoxic shock. Intriguingly, we found that LA1 could significantly reduce mortalities of mice and alleviated pathological injury of liver and lung in endotoxic shock. In vivo studies showed that LA1-induced activation of CD11b significantly inhibited the LPS-induced pro-inflammatory response in macrophages of mice. Moreover, LA1-induced activation of CD11b significantly inhibited LPS/IFN-γ-induced pro-inflammatory response in macrophages by inhibiting MAPKs and NF-κB signaling pathways in vitro. Furthermore, the mice injected with LA1-treated BMDMs showed fewer pathological lesions than those injected with vehicle-treated BMDMs in endotoxic shock. In addition, we found that activation of TLR4 by LPS could endocytose CD11b and activation of CD11b by LA1 could endocytose TLR4 in vitro and in vivo, subsequently blocking the binding of LPS with TLR4. Based on these findings, we concluded that LA1-induced activation of CD11b negatively regulates LPS-induced pro-inflammatory response in macrophages and subsequently protects mice from endotoxin shock by partially blocking LPS-TLR4 interaction. Our study provides a new insight into the role of CD11b in the pathogenesis of inflammatory diseases.

Leukadherin-1-Mediated Activation of CD11b Inhibits LPS-Induced Pro-inflammatory Response in Macrophages and Protects Mice Against Endotoxic Shock by Blocking LPS-TLR4 Interaction

Dysregulation of macrophage has been demonstrated to contribute to aberrant immune responses and inflammatory diseases. CD11b, expressed on macrophages, plays a critical role in regulating pathogen recognition, phagocytosis, and cell survival. In the present study, we explored the effect of leukadherin-1 (LA1), an agonist of CD11b, on regulating LPS-induced pro-inflammatory response in macrophages and endotoxic shock. Intriguingly, we found that LA1 could significantly reduce mortalities of mice and alleviated pathological injury of liver and lung in endotoxic shock. In vivo studies showed that LA1-induced activation of CD11b significantly inhibited the LPS-induced pro-inflammatory response in macrophages of mice. Moreover, LA1-induced activation of CD11b significantly inhibited LPS/IFN-γ-induced pro-inflammatory response in macrophages by inhibiting MAPKs and NF-κB signaling pathways in vitro. Furthermore, the mice injected with LA1-treated BMDMs showed fewer pathological lesions than those injected with vehicle-treated BMDMs in endotoxic shock. In addition, we found that activation of TLR4 by LPS could endocytose CD11b and activation of CD11b by LA1 could endocytose TLR4 in vitro and in vivo, subsequently blocking the binding of LPS with TLR4. Based on these findings, we concluded that LA1-induced activation of CD11b negatively regulates LPS-induced pro-inflammatory response in macrophages and subsequently protects mice from endotoxin shock by partially blocking LPS-TLR4 interaction. Our study provides a new insight into the role of CD11b in the pathogenesis of inflammatory diseases.

Impact of weight cycling on CTRP3 expression, adipose tissue inflammation and insulin sensitivity in C57BL/6J mice

Impacts of weight cycling on C1q/tumor necrosis factor (TNF)-related protein-3 (CTRP3) expression, adipose tissue inflammation and insulin sensitivity in C57BL/6J mice were evaluated in the current study. A total of 30 male C57Bl/6J mice were divided randomly into three groups; normal control (n=10), high-fat diet (OB, n=10) and weight cycling (WC, n=10), which were fed with high-fat diet in the first and last 8 weeks and regular chow in between. Systemic glucose metabolic status and insulin sensitivity were detected by intraperitoneal glucose tolerance test and hyperinsulinemic-euglycemic clamp, respectively. Blood levels of interleukin (IL)-6 and TNF-α were determined using ELISA. Relative CTRP3, IL-6, TNF-α and glucose transporter (GLUT)4 mRNA expression in adipose tissue was detected using reverse transcription-quantitative polymerase chain reaction assays. Relative CTRP3, phosphatidylinositide 3-kinases (PI3K) and protein kinase B (PKB; Ser473) protein expression were detected by western blot analysis. Area under the curve of glucose and glucose infusion rate of the WC group were significantly increased compared with the OB group (P<0.01). CTRP3 mRNA and protein levels of the WC group were significantly decreased by 20.3 and 23.1%, respectively, compared with the OB group (P<0.01). IL-6 and TNF-α protein plasma levels and gene expression in adipose tissue of the WC group were significantly increased compared with the OB group (P<0.01). Expression and phosphorylation of insulin signaling molecules PI3K and PKB (Ser473), respectively and GLUT4 gene expression in adipose tissue of the WC group were significantly decreased compared with the OB group (P<0.01). In conclusion, weight cycling impaired glucose metabolism and insulin sensitivity by decreasing CTRP3, PI3K, phosphorylated-PKB (Ser473) and GLUT4 expression, and increasing IL-6 and TNF-α levels.