Intratracheal IL-6 protects against lung inflammation in direct, but not indirect, causes of acute lung injury in mice

Protective effects of growth hormone - releasing hormone antagonists in the lungs of septic mice

Growth hormone-releasing hormone antagonists (GHRHAnt) have been associated with antitumor and antioxidative activities. The present study investigates for the first time the effects of those compounds towards pro-inflammatory cytokine expression in a murine model of cecal ligation and puncture (CLP) - induced sepsis. The results indicate that GHRHAnt JV-1-36 significantly suppressed IL-1α, IL-6, and pSTAT3 activation in septic lungs. Moreover, GHRHAnt treatment reduced bronchoalveolar lavage fluid (BALF) protein concentration, suggesting a protective effect of that compound in sepsis-induced lung edema. Based on those findings, it is suggested that GHRHAnt may represent an exciting new therapeutic possibility in sepsis-induced endotoxemia and lung injury.

Protective immune response induced by Leghorn male hepatoma cell-adapted fowl adenovirus-4

Fowl adenovirus-4 (FAdV-4) is a highly contagious virus that causes acute and lethal hepatitis. It leads to substantial economic losses in the poultry industry. Among the structural proteins of FAdV-4, hexon and fiber2 are associated with immunopathogenesis. A frameshift mutation was generated in the fiber2 protein by seral passages in the Leghorn male hepatoma (LMH) cell line. Immunization using the attenuated virus (80 times passaged) before the virulent FAdV-4 challenge protected hosts from the infection and cleared the invading virus. In immunized animals, activated CD4+ and CD8+ T cell populations were larger during the FAdV-4 challenge. The change in the B cell population was similar. Myeloid cells were highly increased during FAdV-4 infection after the immunization, but the immunization inhibited the expansion in both liver and spleen. The functional gene expression for immune modulation was strongly associated with immune cell changes in the liver, however, this association was not strong in the spleen. The present findings imply that genetic modification by cellular adaptation regulates immune cell phenotype and function in the target organ. In addition, we suggest the attenuated virus as a protective strategy against the novel FAdV-4 strains.

Interorgan communication networks in the kidney-lung axis

The homeostasis and health of an organism depend on the coordinated interaction of specialized organs, which is regulated by interorgan communication networks of circulating soluble molecules and neuronal connections. Many diseases that seemingly affect one primary organ are really multiorgan diseases, with substantial secondary remote organ complications that underlie a large part of their morbidity and mortality. Acute kidney injury (AKI) frequently occurs in critically ill patients with multiorgan failure and is associated with high mortality, particularly when it occurs together with respiratory failure. Inflammatory lung lesions in patients with kidney failure that could be distinguished from pulmonary oedema due to volume overload were first reported in the 1930s, but have been largely overlooked in clinical settings. A series of studies over the past two decades have elucidated acute and chronic kidney-lung and lung-kidney interorgan communication networks involving various circulating inflammatory cytokines and chemokines, metabolites, uraemic toxins, immune cells and neuro-immune pathways. Further investigations are warranted to understand these clinical entities of high morbidity and mortality, and to develop effective treatments.

Adenovirus type D and type E infection in broiler chickens: the effect on CD4 and CD8 T cell response, cytokines expression and their immunopathology

1. A total of 150-day-old chicks were divided into three groups of 50 birds (G1-G3); G1 and G2 were orally inoculated at 1-day old with 0.5 ml of 107 TCID50/ml FAdV-D serotype 2 (MT386509.1) and FAdV-E serotype 8a (MW847902), respectively, and G3 was blank control group.2. Cell-mediated immune response was evaluated by detection of CD4, CD8 T lymphocytes and the mRNA expression of IL6 and IL8 in the chicken spleen using q-PCR. Additionally, immunopathology was performed at 3, 5 and 7 day post infection (dpi) and weekly until the end of the experiment.3. Results revealed that transcription of inflammatory cytokines (IL6, IL8) was up regulated in the spleen of FAdV type D and type E infected chickens at various time points relative to the control group. A marked decrease in the number of CD4 and CD8 T lymphocytes at 5 and 7 dpi in G1 of chickens infected with FAdV type D. Whereas, in chickens infected with FAdV type E, the CD4 and CD8 T lymphocytes were markedly decreased at 7 dpi.4. In contrast, there were no significant differences in humoral immune responses against NDV vaccine in (G1 and G2) at different intervals post-vaccination compared to the control group. The histopathology of the bursa, thymus, and spleen in the infected groups showed lymphocytolysis with severe reticular cells hyperplasia and lymphoid depletion.5. In conclusion, fowl adenovirus types D and E have an immunosuppressive effect in broilers which may be considered one of the main causes of the continuous co-infections with other viruses reported in the field during the last 10 years.

The mechanism and biomarker function of Cavin-2 in lung ischemia-reperfusion injury

BACKGROUND

Lung Ischemia Reperfusion injury(LIRI) is one of the most predominant complications of ischemic lung disease. Cavin-2 emerged as a regulator of a variety of cellular processes, including endocytosis, lipid homeostasis, signal transduction and tumorigenesis, but the function of Cavin-2 in LIRI is unknown. The purpose of this study was to determine the predictive potential of Cavin-2 in protecting lung ischemia-reperfusion injury and its corresponding mechanisms.

METHODS

We found the strong relationship between Cavin-2 and multiple immune-related genes by deep learning method. To reveal the mechanism of Cavin-2 in LIRI, the LIRI SD rat model was constructed to detect the expression of Cavin-2 in the lung tissue of SD rats after LIRI, and the expression of Cavin-2 in lung cell lines was also detected. The expression of IL-6, IL-10 and MDA in cells after Cavin-2 over-expression or knockdown was examined under hypoxic conditions. The expression levels of p-AKT, p-STAT3 and p-ERK1/2 were measured in over-expressing Cavin-2 cells under hypoxic-ischemia conditions, and then the corresponding blockers of AKT, STAT3 and ERK1/2 were given to verify, whether they play a protective role in LIRI.

RESULTS

After hypoxia, the expression of Cavin-2 in rat lung tissues was significantly increased, and the cellular activity and IL-10 in Cavin-2 over-expressing cells were significantly higher than that of the control group, while IL-6 and MDA were significantly lower than that of the control group, while the above results were reversed in Cavin-2 knockdown cells; Meanwhile, the phosphorylation levels of AKT, STAT3, and ERK1/2 were significantly increased in Cavin-2 over-expression cells after hypoxia. When AKT, STAT3, and ERK1/2 specific blockers were given, they lost their protective effect against LIRI.

CONCLUSIONS

Cavin-2 shows biomarker potential in protecting lung from ischemia-reperfusion injury through the survivor activating factor enhancement (SAFE) and reperfusion injury salvage kinase (RISK) pathway.

Organ Crosstalk in Acute Kidney Injury: Evidence and Mechanisms

Acute kidney injury (AKI) is becoming a public health problem worldwide. AKI is usually considered a complication of lung, heart, liver, gut, and brain disease, but recent findings have supported that injured kidney can also cause dysfunction of other organs, suggesting organ crosstalk existence in AKI. However, the organ crosstalk in AKI and the underlying mechanisms have not been broadly reviewed or fully investigated. In this review, we summarize recent clinical and laboratory findings of organ crosstalk in AKI and highlight the related molecular mechanisms. Moreover, their crosstalk involves inflammatory and immune responses, hemodynamic change, fluid homeostasis, hormone secretion, nerve reflex regulation, uremic toxin, and oxidative stress. Our review provides important clues for the intervention for AKI and investigates important therapeutic potential from a new perspective.

IL-27 Enhances γδ T Cell–Mediated Innate Resistance to Primary Hookworm Infection in the Lungs

IL-27 is a heterodimeric IL-12 family cytokine formed by noncovalent association of the promiscuous EBI3 subunit and selective p28 subunit. IL-27 is produced by mononuclear phagocytes and unfolds pleiotropic immune-modulatory functions through ligation to IL-27 receptor α (IL-27RA). Although IL-27 is known to contribute to immunity and to limit inflammation after various infections, its relevance for host defense against multicellular parasites is still poorly defined. Here, we investigated the role of IL-27 during infection with the soil-transmitted hookworm, Nippostrongylus brasiliensis, in its early host intrapulmonary life cycle. IL-27(p28) was detectable in bronchoalveolar lavage fluid of C57BL/6J wild-type mice on day 1 after s.c. inoculation. IL-27RA expression was most abundant on lung-invading γδ T cells. Il27ra^-/- mice showed increased lung parasite burden together with aggravated pulmonary hemorrhage and higher alveolar total protein leakage as a surrogate for epithelial-vascular barrier disruption. Conversely, injections of recombinant mouse (rm)IL-27 into wild-type mice reduced lung injury and parasite burden. In multiplex screens, higher airway accumulations of IL-6, TNF-α, and MCP-3 (CCL7) were observed in Il27ra^-/- mice, whereas rmIL-27 treatment showed a reciprocal effect. Importantly, γδ T cell numbers in airways were enhanced by endogenous or administered IL-27. Further analysis revealed a direct antihelminthic function of IL-27 on γδ T cells as adoptive intratracheal transfer of rmIL-27-treated γδ T cells during primary N. brasiliensis lung infection conferred protection in mice. In summary, this report demonstrates protective functions of IL-27 to control the early lung larval stage of hookworm infection.

Interorgan crosstalk mechanisms in disease: the case of acute kidney injury-induced remote lung injury

Homeostasis and health of multicellular organisms with multiple organs depends on interorgan communication. Tissue injury in one organ disturbs this homeostasis and can lead to disease in multiple organs, or multiorgan failure. Many routes of interorgan crosstalk during homeostasis are relatively well known, but interorgan crosstalk in disease still lacks understanding. In particular, how tissue injury in one organ can drive injury at remote sites and trigger multiorgan failure with high mortality is poorly understood. As examples, acute kidney injury can trigger acute lung injury and cardiovascular dysfunction; pneumonia, sepsis or liver failure conversely can cause kidney failure; lung transplantation very frequently triggers acute kidney injury. Mechanistically, interorgan crosstalk after tissue injury could involve soluble mediators and their target receptors, cellular mediators, in particular immune cells, as well as newly identified neuro-immune connections. In this review, I will focus the discussion of deleterious interorgan crosstalk and its mechanistic concepts on one example, acute kidney injury-induced remote lung injury.

Phenotypes, Lung Microbiota and Cytokine Responses in Pneumonia After Hematopoietic Stem Cell Transplantation

Objective

We aim to identify phenotypes of hematopoietic stem cell transplantation (HSCT) patients with pneumonia, discover relations of microbiota composition, cytokine profile, and outcomes between phenotypes. Specific cytokines will be evaluated for their role in lung injury in a murine model.

Methods

HSCT patients with pneumonia were included, and clustering of variables including cytokine levels provided the phenotypes. Outcomes were compared between phenotypes. Analysis of lung microbiota identified marker species of phenotypes. In the murine model, marker species-related cytokine regulations and the role of cytokines in lung injury were evaluated.

Results

Seventy-two patients were included, and two phenotypes were identified, namely "reactive" (N=21) and "nonreactive" (N=51) phenotype. Compared to their counterparts, patients with nonreactive phenotype had lower serum IL-6, IL-8, less severe inflammation, worse outcomes and more viruses as marker species in lung microbiota. The animal study validated the pathogens specific cytokine responses that presented in the human study and the potential protective role of IL-6 in these patients.

Conclusion

HSCT patients with pneumonia can be clustered into two phenotypes with different marker species and outcomes: the "nonreactive" phenotype and the "reactive" phenotype. Serum cytokine levels were different between the two phenotypes, which indicate the existence of the pathogen-related cytokine responses. For patients with the "nonreactive" phenotype, IL-6 therapy may improve their prognosis, which should be further tested in clinical studies.

Protein and peptide delivery to lungs by using advanced targeted drug delivery

The challenges and difficulties associated with conventional drug delivery systems have led to the emergence of novel, advanced targeted drug delivery systems. Therapeutic drug delivery of proteins and peptides to the lungs is complicated owing to the large size and polar characteristics of the latter. Nevertheless, the pulmonary route has attracted great interest today among formulation scientists, as it has evolved into one of the important targeted drug delivery platforms for the delivery of peptides, and related compounds effectively to the lungs, primarily for the management and treatment of chronic lung diseases. In this review, we have discussed and summarized the current scenario and recent developments in targeted delivery of proteins and peptide-based drugs to the lungs. Moreover, we have also highlighted the advantages of pulmonary drug delivery over conventional drug delivery approaches for peptide-based drugs, in terms of efficacy, retention time and other important pharmacokinetic parameters. The review also highlights the future perspectives and the impact of targeted drug delivery on peptide-based drugs in the coming decade.

Acute Kidney Injury and Acute Respiratory Distress Syndrome

Acute kidney injury (AKI) complicates approximately a third of all acute respiratory distress syndrome (ARDS) cases, and the combination of the two drastically worsens prognosis. Recent advances in ARDS supportive care have led to improved outcomes; however, much less is known on how to prevent and support patients with AKI and ARDS together. Understanding the dynamic relationship between the kidneys and lungs is crucial for the practicing intensivist to prevent injury. This article summarizes key concepts for the critical care physician managing a patient with ARDS complicated by AKI. Also provided is a discussion of AKI in the COVID-19 era.

Efficacy comparison of high-frequency oscillatory ventilation with continuous nasal positive airway pressure in neonatal respiratory distress syndrome treatment

OBJECTIVES

To compare the treatment efficacy of high-frequency oscillatory ventilation (HFOV) with nasal continuous positive airway pressure (NCPAP) in the treatment of neonatal respiratory distress syndrome (NRDS) and its effect on the expression of high-mobility group protein B1 (HMGB1).

METHODS

A total of 180 infants with NRDS admitted to our hospital were included and randomly assigned into the HFOV group (receiving conventional therapy and HFOV), the NCPAP group (receiving conventional therapy and NCPAP), and the conventional group (receiving conventional therapy). Qi and blood indicators, heart rate, respiratory frequency, PCO₂, and PaO₂ were observed and recorded before and after treatment, together with complications after treatment. ELISA was performed for HMGB1 Results: A distinctly lower partial pressure of carbon dioxide (PCO₂) but higher arterial partial pressure of oxygen (PaO₂) was observed in the HFOV and NCPAP groups than in the conventional group (P < 0.05), whereas infants in the HFOV group exhibited slight differences in these two indicators from their counterparts in the NCPAP group (P > 0.05). The serum HMGB1 levels in both groups were significantly higher than those in the conventional group (P < 0.05).

DISCUSSION

Both HFOV and NCPAP are feasible in the treatment of NRDS and may play a role in the inhibition of HMGB1.

Oral inhalation for delivery of proteins and peptides to the lungs

Oral inhalation is the preferred route for delivery of small molecules to the lungs, because high tissue levels can be achieved shortly after application. Biologics are mainly administered by intravenous injection but inhalation might be beneficial for the treatment of lung diseases (e.g. asthma). This review discusses biological and pharmaceutical challenges for delivery of biologics and describes promising candidates. Insufficient stability of the proteins during aerosolization and the biological environment of the lung are the main obstacles for pulmonary delivery of biologics. Novel nebulizers will improve delivery by inducing less shear stress and administration as dry powder appears suitable for delivery of biologics. Other promising strategies include pegylation and development of antibody fragments, while carrier-encapsulated systems currently play no major role in pulmonary delivery of biologics for lung disease. While development of various biologics has been halted or has shown little effects, AIR DNase, alpha1-proteinase inhibitor, recombinant neuraminidase, and heparin are currently being evaluated in phase III trials. Several biologics are being tested for the treatment of coronavirus disease (COVID)-19, and it is expected that these trials will lead to improvements in pulmonary delivery of biologics.

Adipose-derived mesenchymal stem cells attenuate dialysis-induced peritoneal fibrosis by modulating macrophage polarization via interleukin-6

Background

Life-long peritoneal dialysis (PD) as a renal replacement therapy is limited by peritoneal fibrosis. Previous studies showed immunomodulatory and antifibrotic effects of adipose-derived mesenchymal stem cells (ADSCs) on peritoneal fibrosis. However, the role of the peritoneal macrophage in this process remains uninvestigated.

Methods

We examined the therapeutic effects of ADSC and bone marrow-derived mesenchymal stem cells (BM-MSC) in the rat model of dialysis-induced peritoneal fibrosis using methylglyoxal. In addition, treatment of macrophages with the conditioned medium of ADSC and BM-MSC was performed individually to identify the beneficial component of the stem cell secretome.

Results

In the in vivo experiments, we found dialysis-induced rat peritoneal fibrosis was attenuated by both ADSC and BM-MSC. Interestingly, ADSC possessed a more prominent therapeutic effect than BM-MSC in ameliorating peritoneal membrane thickening while also upregulating epithelial cell markers in rat peritoneal tissues. The therapeutic effects of ADSC were positively associated with M2 macrophage polarization. In the in vitro experiments, we confirmed that interleukin-6 (IL-6) secreted by MSCs upon transforming growth factor-β1 stimulation promotes M2 macrophage polarization.

Conclusions

In dialysis-induced peritoneal fibrosis, MSCs are situated in an inflammatory environment of TGF-β1 and secrete IL-6 to polarize macrophages into the M2 phenotype. Our findings reveal a previously unidentified role of tissue macrophage in this antifibrotic process. ADSC has the advantage of abundance and accessibility, making the application values extremely promising.

Graphical abstract

In dialysis-induced peritoneal fibrosis, peritoneal mesothelial cells secrete transforming growth factor-β1 (TGF-β1) when exposed to methylglyoxal (MGO)-containing peritoneal dialysate. When situated in TGF-β1, the inflammatory environment induces mesenchymal stem cells to secrete interleukin-6 (IL-6), IL-6 polarizes macrophages into the M2 phenotype. The dominant peritoneal tissue M2 macrophages, marked by upregulated Arg-1 expression, account for the attenuation of MGO-induced dedifferentiation of peritoneal mesothelial cells to maintain epithelial integrity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02270-4.

Inhibiting the ROCK Pathway Ameliorates Acute Lung Injury in Mice following Myocardial Ischemia/reperfusion

To clarify the role of Y-27632, a selective inhibitor of Rho-associated coiled-coil forming protein kinase (ROCK), in acute lung injury (ALI) induced by myocardial ischemia/reperfusion (I/R). Mice were randomized into Sham, I/R, and Y-27632 (10, 20 or 30 mg/kg) + I/R groups, and hemodynamics, infarcted area, the protein concentration, neutrophils in bronchoalveolar lavage fluid (BALF), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels were assessed. Pathological changes were evaluated by hematoxylin-eosin (HE) staining; protein and gene expression were measured by Western blotting, enzyme-linked immunosorbent assay (ELISA), immunohistochemistry and quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR); and apoptosis was assessed by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) staining. ROCK1 and ROCK2 expression was up-regulated in lung tissues of I/R mice compared to sham mice. Y-27632 decreased the protein concentration and the neutrophils in BALF in I/R mice, improved hemodynamics and reduced infarct size (IS)/area at risk (AAR) ratio. In addition, pathological changes in lung tissues of Y-27632-treated mice were mitigated, and these alterations were accompanied by decreases in MDA levels in lung tissues and increases in SOD and GSH-Px levels. Moreover, in I/R group, the number of apoptotic cells in lung tissue was higher than that in sham group, and p53, Caspase-3 and Bax expression was up-regulated; however, following treatment with Y-27632 (10, 20 and 30 mg/kg), these changes were reversed. Inhibition of ROCK pathway by Y-27632 ameliorated ALI in myocardial I/R mice by mitigating oxidative stress, inflammation and cell apoptosis.

Initial In Vivo Evaluation of a Novel Amikacin-Deoxycholate Hydrophobic Salt Delivers New Insights on Amikacin Partition in Blood and Tissues

In this study, an initial in vivo evaluation of a new amikacin-deoxycholate hydrophobic salt aimed at potentiating amikacin action against hard-to-treat lung infections was undertaken by quantifying, for the first time, amikacin in whole blood. Pharmacokinetic evaluation after intranasal administration in a murine model showed higher drug retention in the lungs compared to blood, with no significant differences between the salt and the free drug. Upon repeated administrations, the two treatments resulted in nonsignificant tissue damage and mild higher inflammation for the hydrophobic salt. Whole-blood analysis highlighted an unreported high partition of amikacin in blood components up to 48 h, while significant lung levels were measured up to 72 h. Such a new observation was considered responsible for the nearly overlapping pharmacokinetic profiles of the two treatments. To overcome such an issue, a dry powder in an inhalable form may be best suited. Moreover, if confirmed in humans, and considering the current once-a-day regimen for amikacin aerosols, important yet-to-be-explored clinical implications may be postulated for such amikacin persistence in the organism.

Two to Tango: Kidney-Lung Interaction in Acute Kidney Injury and Acute Respiratory Distress Syndrome

Acute Kidney Injury (AKI) is an independent risk factor for mortality in hospitalized patients. AKI syndrome leads to fluid overload, electrolyte and acid-base disturbances, immunoparalysis, and propagates multiple organ dysfunction through organ "crosstalk". Preclinical models suggest AKI causes acute lung injury (ALI), and conversely, mechanical ventilation and ALI cause AKI. In the clinical setting, respiratory complications are a key driver of increased mortality in patients with AKI, highlighting the bidirectional relationship. This article highlights the challenging and complex interactions between the lung and kidney in critically ill patients with AKI and acute respiratory distress syndrome (ARDS) and global implications of AKI. We discuss disease-specific molecular mediators and inflammatory pathways involved in organ crosstalk in the AKI-ARDS construct, and highlight the reciprocal hemodynamic effects of elevated pulmonary vascular resistance and central venous pressure (CVP) leading to renal hypoperfusion and pulmonary edema associated with fluid overload and increased right ventricular afterload. Finally, we discuss the notion of different ARDS "phenotypes" and the response to fluid overload, suggesting differential organ crosstalk in specific pathological states. While the directionality of effect remains challenging to distinguish at the bedside due to lag in diagnosis with conventional renal function markers and lack of tangible damage markers, this review provides a paradigm for understanding kidney-lung interactions in the critically ill patient.

K2P2.1 (TREK-1) potassium channel activation protects against hyperoxia-induced lung injury

No targeted therapies exist to counteract Hyperoxia (HO)-induced Acute Lung Injury (HALI). We previously found that HO downregulates alveolar K_2P2.1 (TREK-1) K⁺ channels, which results in worsening lung injury. This decrease in TREK-1 levels leaves a subset of channels amendable to pharmacological intervention. Therefore, we hypothesized that TREK-1 activation protects against HALI. We treated HO-exposed mice and primary alveolar epithelial cells (AECs) with the novel TREK-1 activators ML335 and BL1249, and quantified physiological, histological, and biochemical lung injury markers. We determined the effects of these drugs on epithelial TREK-1 currents, plasma membrane potential (Em), and intracellular Ca²⁺ (iCa) concentrations using fluorometric assays, and blocked voltage-gated Ca²⁺ channels (Ca_V) as a downstream mechanism of cytokine secretion. Once-daily, intra-tracheal injections of HO-exposed mice with ML335 or BL1249 improved lung compliance, histological lung injury scores, broncho-alveolar lavage protein levels and cell counts, and IL-6 and IP-10 concentrations. TREK-1 activation also decreased IL-6, IP-10, and CCL-2 secretion from primary AECs. Mechanistically, ML335 and BL1249 induced TREK-1 currents in AECs, counteracted HO-induced cell depolarization, and lowered iCa²⁺ concentrations. In addition, CCL-2 secretion was decreased after L-type Ca_V inhibition. Therefore, Em stabilization with TREK-1 activators may represent a novel approach to counteract HALI.

The performance of the alarmin HMGB1 in pediatric diseases: From lab to clinic

INTRODUCTION

The ubiquitously expressed nonhistone nuclear protein high-mobility group box protein 1 (HMGB1) has different functions related to posttranslational modifications and cellular localization. In the nucleus, HMGB1 modulates gene transcription, replication and DNA repair as well as determines chromosomal architecture. When the post-transcriptional modified HMGB1 is released into the extracellular space, it triggers several physiological and pathological responses and initiates innate immunity through interacting with its reciprocal receptors (i.e., TLR4/2 and RAGE). The effect of HMGB1-mediated inflammatory activation on different systems has received increasing attention. HMGB1 is now considered to be an alarmin and participates in multiple inflammation-related diseases. In addition, HMGB1 also affects the occurrence and progression of tumors. However, most studies involving HMGB1 have been focused on adults or mature animals. Due to differences in disease characteristics between children and adults, it is necessary to clarify the role of HMGB1 in pediatric diseases.

METHODS AND RESULTS

Through systematic database retrieval, this review aimed to first elaborate the characteristics of HMGB1 under physiological and pathological conditions and then discuss the clinical significance of HMGB1 in the pediatric diseases according to different systems.

CONCLUSIONS

HMGB1 plays an important role in a variety of pediatric diseases and may be used as a diagnostic biomarker and therapeutic target for new strategies for the prevention and treatment of pediatric diseases.

Dual Effect of Soloxolone Methyl on LPS-Induced Inflammation In Vitro and In Vivo

Plant-extracted triterpenoids belong to a class of bioactive compounds with pleotropic functions, including antioxidant, anti-cancer, and anti-inflammatory effects. In this work, we investigated the anti-inflammatory and anti-oxidative activities of a semisynthetic derivative of 18βH-glycyrrhetinic acid (18βH-GA), soloxolone methyl (methyl 2-cyano-3,12-dioxo-18βH-olean-9(11),1(2)-dien-30-oate, or SM) in vitro on lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and in vivo in models of acute inflammation: LPS-induced endotoxemia and carrageenan-induced peritonitis. SM used at non-cytotoxic concentrations was found to attenuate the production of reactive oxygen species and nitric oxide (II) and increase the level of reduced glutathione production by LPS-stimulated RAW264.7 cells. Moreover, SM strongly suppressed the phagocytic and migration activity of activated macrophages. These effects were found to be associated with the stimulation of heme oxigenase-1 (HO-1) expression, as well as with the inhibition of nuclear factor-κB (NF-κB) and Akt phosphorylation. Surprisingly, it was found that SM significantly enhanced LPS-induced expression of the pro-inflammatory cytokines interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) in RAW264.7 cells via activation of the c-Jun/Toll-like receptor 4 (TLR4) signaling axis. In vivo pre-exposure treatment with SM effectively inhibited the development of carrageenan-induced acute inflammation in the peritoneal cavity, but it did not improve LPS-induced inflammation in the endotoxemia model.

The Role of Cytokines including Interleukin-6 in COVID-19 induced Pneumonia and Macrophage Activation Syndrome-Like Disease

Severe COVID-19 associated pneumonia patients may exhibit features of systemic hyper-inflammation designated under the umbrella term of macrophage activation syndrome (MAS) or cytokine storm, also known as secondary haemophagocytic lymphohistocytosis (sHLH). This is distinct from HLH associated with immunodeficiency states termed primary HLH -with radically different therapy strategies in both situations. COVID-19 infection with MAS typically occurs in subjects with adult respiratory distress syndrome (ARDS) and historically, non-survival in ARDS was linked to sustained IL-6 and IL-1 elevation. We provide a model for the classification of MAS to stratify the MAS-like presentation in COVID-19 pneumonia and explore the complexities of discerning ARDS from MAS. We discuss the potential impact of timing of anti-cytokine therapy on viral clearance and the impact of such therapy on intra-pulmonary macrophage activation and emergent pulmonary vascular disease.

Fraxin Alleviates LPS-Induced ARDS by Downregulating Inflammatory Responses and Oxidative Damages and Reducing Pulmonary Vascular Permeability

Acute respiratory distress syndrome (ARDS) is a severe acute disease that threatens human health, and few drugs that can effectively treat this disease are available. Fraxin, one of the main active ingredients of Cortex Fraxini, a Chinese herbal medicine, has presented various pharmacological and biological activities. However, the effects of fraxin on ARDS have yet to be reported. In the present study, the protective effect of fraxin in lipopolysaccharide (LPS)-induced ARDS in a mouse model was analyzed. Results from the hematoxylin and eosin staining showed that fraxin might alleviate pathological changes in the lung tissues of mice with ARDS. ELISA and Western blot results revealed that fraxin might inhibit the production of inflammatory factors, namely, IL-6, TNF-α, and IL-1β, and the activation of NF-κB and MAPK signaling pathways in the lungs. Thus, the inflammatory responses were reduced. Fraxin might inhibit the increase in reactive oxygen species (ROS) and malondialdehyde (MDA), a product of lipid peroxidation in lung tissues. Fraxin might increase the superoxide dismutase (SOD) activity to avoid oxidative damage. Vascular permeability was also assessed through Evans blue dye tissue extravasation and fluorescein isothiocyanate-labeled albumin (FITC-albumin) leakage. Fraxin might inhibit the increase in pulmonary vascular permeability and relieve pulmonary edema. Fraxin was also related to the inhibition of the increase in matrix metalloproteinase-9, which is a glycocalyx-degrading enzyme, and the relief of damages to the endothelial glycocalyx. Thus, fraxin elicited protective effects on mice with LPS-induced ARDS and might be used as a drug to cure ARDS induced by Gram-negative bacterial infection.

A pulmonary source of infection in patients with sepsis-associated acute kidney injury leads to a worse outcome and poor recovery of kidney function

BACKGROUND

Hospital mortality rates are higher among patients with sepsis-associated acute kidney injury (SA-AKI) than among patients with sepsis. However, the pathogenesis underlying SA-AKI remains unclear. We hypothesized that the source of infection affects development of SA-AKI. We aim to explore the relationship between the anatomical source of infection and outcome in patients with SA-AKI.

METHODS

Between January 2013 and January 2018, 113 patients with SA-AKI admitted to our Emergency Center were identified and divided into two groups: those with pulmonary infections and those with other sources of infection. For each patient, we collected data from admission until either discharge or death. We also recorded the clinical outcome after 90 days for the discharged patients.

RESULTS

The most common source of infection was the lung (52/113 cases, 46%), followed by gastrointestinal (GI) (25/113 cases, 22.1%) and urinary (22/113, 19.5%) sources. Our analysis showed that patients with SA-AKI had a significantly worse outcome (30/52 cases, P<0.001) and poorer kidney recovery (P=0.015) with pulmonary sources of infection than those infected by another source. Data also showed that patients not infected by a pulmonary source more likely experienced shock (28/61 cases, P=0.037).

CONCLUSION

This study demonstrated that the source of infection influenced the outcome of SA-AKI patients in an independent manner. Lung injury may influence renal function in an as-yet undetermined manner as the recovery of kidney function was poorer in SA-AKI patients with a pulmonary source of infection.

IL-6-mediated hepatocyte production is the primary source of plasma and urine neutrophil gelatinase-associated lipocalin during acute kidney injury

Neutrophil gelatinase associated lipocalin (NGAL, Lcn2) is the most widely studied biomarker of acute kidney injury (AKI). Previous studies have demonstrated that NGAL is produced by the kidney and released into the urine and plasma. Consequently, NGAL is currently considered a tubule specific injury marker of AKI. However, the utility of NGAL to predict AKI has been variable suggesting that other mechanisms of production are present. IL-6 is a proinflammatory cytokine increased in plasma by two hours of AKI and mediates distant organ effects. Herein, we investigated the role of IL-6 in renal and extra-renal NGAL production. Wild type mice with ischemic AKI had increased plasma IL-6, increased hepatic NGAL mRNA, increased plasma NGAL, and increased urine NGAL; all reduced in IL-6 knockout mice. Intravenous IL-6 in normal mice increased hepatic NGAL mRNA, plasma NGAL and urine NGAL. In mice with hepatocyte specific NGAL deletion (Lcn2hep-/-) and ischemic AKI, hepatic NGAL mRNA was absent, and plasma and urine NGAL were reduced. Since urine NGAL levels appear to be dependent on plasma levels, the renal handling of circulating NGAL was examined using recombinant human NGAL. After intravenous recombinant human NGAL administration to mice, human NGAL in mouse urine was detected by ELISA during proximal tubular dysfunction, but not in pre-renal azotemia. Thus, during AKI, IL-6 mediates hepatic NGAL production, hepatocytes are the primary source of plasma and urine NGAL, and plasma NGAL appears in the urine during proximal tubule dysfunction. Hence, our data change the paradigm by which NGAL should be interpreted as a biomarker of AKI.

Carnosic acid protects against lipopolysaccharide-induced acute lung injury in mice

Acute respiratory distress syndrome is a well-known inflammatory disease associated with high rates of morbidity and mortality due to a lack of effective treatment methods. Carnosic acid (CA) is a phenolic diterpene compound that serves a central role in cytoprotective responses to inflammation. In the present study, the protective mechanism of CA on acute lung injury (ALI) induced by lipopolysaccharide (LPS) was investigated. Mice were randomly assigned to the following five groups: Control group, LPS group, and LPS plus CA groups (at 10, 20 and 40 mg/kg doses). Following pre-treatment with vehicle or CA, ALI was induced by the administration of LPS. At 6 h after LPS treatment, mice were sacrificed and lung tissues were harvested for histologic analysis and the determination of wet-to-dry ratio, myeloperoxidase activity and toll-like receptor 4 (TLR4) and NF-κB expression. Additionally, the levels of interleukin (IL)-1β, IL-6 and tumor necrosis factor-α (TNF-α) were determined in bronchoalveolar lavage fluid (BALF) and lung tissues, as well as the rate of apoptosis of the isolated neutrophils from BALF. The alleviation of LPS-induced ALI by CA was confirmed by histologic results and a reduction in the wet-to-dry ratio of lung tissues. Additionally, CA was revealed to significantly suppress the inhibitory effect of LPS on neutrophil apoptosis and the promoting effects of LPS on IL-1β, IL-6, TNF-α, TLR4 and NF-κB expression, and NF-κB phosphorylation. The current results indicated that CA protects against LPS-induced ALI via a mechanism that inhibits inflammation.

Immunosuppressive potential of fowl adenovirus serotype 4

Fowl adenovirus serotype 4 (FAdV-4) is the causative agent of hydropericardium syndrome. To clarify the effects of FAdV-4 on immune organs in birds, we conducted a detailed examination of dynamic morphology and damage mechanisms in chickens randomly divided into 4 groups (FAdV-4, vaccination, FAdV-4 plus vaccination, and control). FAdV-4 caused the depletion of lymphocytes and subsequent growth impairment in the thymus and bursa. Chickens infected with FAdV-4 and subjected to vaccination experienced greater inhibition of antibody responses to inactivated vaccines against Newcastle disease and avian influenza virus subtype H9 than uninfected and vaccinated chickens. The mechanisms underlying adenovirus-mediated lymphoid organ damage were further investigated via transferase-mediated dUTP nick-end labeling and apoptotic genes transcription analyses. Notably, lymphocytes apoptosis in lymphoid organs and expression of specific gene transcripts was significantly upregulated after infection (P < 0.05). Furthermore, increased expression of interleukin (IL)-6, IL-8, and tumor necrosis factor (TNF)-α mRNA was observed (P < 0.05), compared to the control group. Our collective findings suggested that FAdV-4 caused structural and functional damage of immune organs via apoptosis along with induction of a severe inflammatory response.

Novel insights into the role of LRRC8A in ameliorating alveolar fluid clearance in LPS induced acute lung injury

Leucine-rich repeat-containing 8A (LRRC8A) protein was recently identified as an essential component of volume-regulated anion channel which plays a central role in maintaining cell volume. The aim of this study was to elucidate the role of LRRC8A in alveolar fluid clearance (AFC) and the effect of inflammatory cytokines on LRRC8A and the underlying mechanism. Lipopolysaccharide (LPS) was used to generate a rat acute lung injury model. The results showed that the concentrations of IL-1β, TNF-α and IL-6 in bronchoalveolar lavage fluid increased significantly, but the expression of LRRC8A in the lung tissue decreased dramatically in the acute lung injury group followed by a decline in the AFC rate. Additionally, LRRC8A knockdown reduced AFC in normal rats. However, specific overexpression of LRRC8A in the lung could increase AFC. Furthermore, we observed the effects of LPS, IL-1β, TNF-α and IL-6 on the LRRC8A current in alveolar type II (ATII) cells, and IL-1β showed the greatest inhibition among them, which was involved in phospho-p38 activation. Overall, LRRC8A plays an essential role in the progression of AFC in LPS-induced acute lung injury, and chronic treatment with IL-1β or TNF-α could inhibit the function of LRRC8A in ATII cells by targeting phospho-p38. All of the findings suggested that LRRC8A could be a new partner in AFC and a potential target for the treatment of acute lung injury.

Identification, Pathogenicity of Novel Fowl Adenovirus Serotype 4 SDJN0105 in Shandong, China and Immunoprotective Evaluation of the Newly Developed Inactivated Oil-emulsion FAdV-4 Vaccine

Since mid-2015, numerous outbreaks of hydropericardium-hepatitis syndrome (HHS), which is caused by a novel fowl adenovirus serotype 4 (FAdV-4), have been reported in chickens in parts of China, thereby causing huge economic losses to the poultry industry. Thus, an effective vaccine to control the further spread of infections with this hyper-virulent FAdV-4 is imperative. In this study, we isolated a novel FAdV-4 strain SDJN0105 from a broiler farm with HHS disease in Shandong Province. Pathogenicity was evaluated by the observation of clinical symptoms, necropsy changes, and pathological tissue sections after oral and intramuscular (IM) infection of Specific pathogen free (SPF) chickens. The chickens infected by IM injection all died within three days, and chickens infected via the oculonasal route died within five days post-infection (dpi). Histopathological examination revealed that the pathology was confined to heart, liver, spleen, lung, kidney, and particularly the liver. Irrespective of the inoculation route, the highest viral DNA copy numbers were detected in the livers of infected chickens. The mRNA expression levels of IL-1β, IL-6, IL-8, IFNs, TNF-α, Mx, and OASL were significantly upregulated during the viral infection. In addition, an inactivated oil-emulsion FAdV-4 vaccine was developed. The vaccine could provide full protection for SPF chickens against a lethal dose of the FAdV-4 strain SDJN0105 and a high level of antibodies. These results improve our understanding of the innate immune responses in chickens infected with FAdV-4 and the pathogenesis of FAdV-4 caused by host factors, and the developed FAdV-4 vaccine is promising as a drug candidate for the prevention and reduction of the spread of HHS in poultry in China.

Mesenchymal Stem Cells Reconditioned in Their Own Serum Exhibit Augmented Therapeutic Properties in the Setting of Acute Respiratory Distress Syndrome

Mesenchymal stem cells (MSCs) are a promising form of therapy for acute respiratory distress syndrome (ARDS). The objective of this study was twofold: (a) to characterize cytokine expression in serum from ARDS subjects receiving MSCs and (b) to determine MSC function following “preconditioning” with ARDS serum. In phase I, serum from three cohorts of animals (uninjured [no ARDS, n = 4], injured untreated [n = 5], and injured treated with approximately 6 million per kilogram MSCs [n = 7]) was analyzed for expression of inflammatory mediators. In phase II, the functional properties of bone marrow porcine MSCs were assessed following “preconditioning” with serum from the three cohorts. In phase III, the findings from the previous phases were validated using human bone marrow MSCs (hBM‐MSCs) and lipopolysaccharide (LPS). Serum from injured treated animals had significantly lower levels of interferon‐γ and significantly higher levels of interleukin (IL)‐1 receptor antagonist (IL‐1RA) and IL‐6. Similarly, upon exposure to the injured treated serum ex vivo, the MSCs secreted higher levels of IL‐1RA and IL‐10, dampened the secretion of proinflammatory cytokines, exhibited upregulation of toll‐like receptor 4 (TLR‐4) and vascular endothelial growth factor (VEGF) genes, and triggered a strong immunomodulatory response via prostaglandin E2 (PGE₂). hBM‐MSCs demonstrated a similar augmented therapeutic function following reconditioning in a LPS milieu. Administration of MSCs modulated the inflammatory milieu following ARDS. Exposure to ARDS serum ex vivo paralleled the trends seen in vivo, which appear to be mediated, in part, through TLR‐4 and VEGF and PGE₂. Reconditioning MSCs in their own serum potentiates their immunotherapeutic function, a technique that can be used in clinical applications. stem cells translational medicine2019;8:1092–1106

Organ Failure Due to Systemic Injury in Acute Pancreatitis

Acute pancreatitis may be associated with both local and systemic complications. Systemic injury manifests in the form of organ failure, which is seen in approximately 20% of all cases of acute pancreatitis and defines "severe acute pancreatitis." Organ failure typically develops early in the course of acute pancreatitis, but also may develop later due to infected pancreatic necrosis-induced sepsis. Organ failure is the most important determinant of outcome in acute pancreatitis. We review here the current understanding of the risk factors, pathophysiology, timing, impact on outcome, and therapy of organ failure in acute pancreatitis. As we discuss the pathophysiology of severe systemic injury, the distinctions between markers and mediators of severity are highlighted based on evidence supporting their causality in organ failure. Emphasis is placed on clinically relevant end points of organ failure and the mechanisms underlying the pathophysiological perturbations, which offer insight into potential therapeutic targets to treat.

Fowl adenovirus serotype 4-induced apoptosis, autophagy, and a severe inflammatory response in liver

Fowl adenovirus serotype 4 (FAdV-4) is a hepatotrophic virus that causes severe liver diseases. Upon histological examination, the most remarkable findings in the liver are small multifocal areas of necrosis and mononuclear cell infiltration, including basophilic intranuclear inclusion bodies in hepatocytes surrounded by a clear halo or which fill the entire nucleus. Here, we examined the mechanism responsible for FAdV-4-mediated hepatocyte damage in vivo and in vitro. The results showed that FAdV-4 impaired liver integrity and function, which decreased albumin and blood glucose concentrations and increased the plasma activity of aspartate aminotransferase and lactate dehydrogenase, compared with a non-infected control group (P<0.05). FAdV-4 induced hepatocyte apoptosis in a time-dependent manner in vivo and in vitro. Additionally, we found that FAdV-4 also induced the autophagy of hepatocytes, which promoted the conversion of microtubule-associated protein light chain 3 (LC3-I) to LC3-II, which is a hallmarks of autophagy. Furthermore, the mRNA expressions of interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α in vivo and in vitro showed a statistically significant increase (P<0.05) compared to that of the control group. However, the molecular mechanisms underlying the FAdV-4-induced apoptotic and autophagic cell death remain unclear. In summation, our observations suggested that FAdV-4 induced liver injury via apoptosis, autophagy, and a severe inflammatory response.

Intratracheal instillation of alveolar type II cells enhances recovery from acute lung injury in rats

BACKGROUND

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are characterized by excess production of inflammatory factors. Alveolar type II (ATII) cells help repair damaged lung tissue, rapidly proliferating and differentiating into alveolar type I cells after epithelial cell injury. In ALI, the lack of viable ATII favors progression to more severe lung injury. ATII cells regulate the immune response by synthesizing surfactant and other anti-inflammatory proteins and lipids. Cross-talk between ATII and other cells such as macrophages may also be part of the ATII function. The aim of this study was to test the anti-inflammatory and reparative effects of ATII cells in an experimental model of ALI.

METHODS

In this study ATII cells (2.5 × 10⁶ cells/animal) were intratracheally instilled in rats with HCl and lipopolysaccharide (LPS)-induced ALI and in healthy animals to check for side effects. The specific effect of ATII cells was compared with fibroblast transplantation.

RESULTS

ATII cell transplantation promoted recovery of lung function, decrease mortality and lung inflammation of the animals with ALI. The primary mechanisms for benefit were paracrine effects of prostaglandin E₂ (PGE₂) and surfactant protein A (SPA) released from ATII cells that modulate alveolar macrophages to an anti-inflammatory phenotype. To our knowledge, these data are the first to provide evidence that ATII cells secrete PGE₂ and SPA, reducing pro-inflammatory macrophage activation and ALI.

CONCLUSION

ATII cells and their secreted molecules have shown an ability to resolve ALI, thereby highlighting a potential novel therapeutic target.

Treatments for Pulmonary Ricin Intoxication: Current Aspects and Future Prospects

Ricin, a plant-derived toxin originating from the seeds of Ricinus communis (castor beans), is one of the most lethal toxins known, particularly if inhaled. Ricin is considered a potential biological threat agent due to its high availability and ease of production. The clinical manifestation of pulmonary ricin intoxication in animal models is closely related to acute respiratory distress syndrome (ARDS), which involves pulmonary proinflammatory cytokine upregulation, massive neutrophil infiltration and severe edema. Currently, the only post-exposure measure that is effective against pulmonary ricinosis at clinically relevant time-points following intoxication in pre-clinical studies is passive immunization with anti-ricin neutralizing antibodies. The efficacy of this antitoxin treatment depends on antibody affinity and the time of treatment initiation within a limited therapeutic time window. Small-molecule compounds that interfere directly with the toxin or inhibit its intracellular trafficking may also be beneficial against ricinosis. Another approach relies on the co-administration of antitoxin antibodies with immunomodulatory drugs, thereby neutralizing the toxin while attenuating lung injury. Immunomodulators and other pharmacological-based treatment options should be tailored according to the particular pathogenesis pathways of pulmonary ricinosis. This review focuses on the current treatment options for pulmonary ricin intoxication using anti-ricin antibodies, disease-modifying countermeasures, anti-ricin small molecules and their various combinations.

Obesity and pancreatitis

PURPOSE OF REVIEW

The obesity pandemic poses a unique set of problems for acute pancreatitis - both by increasing acute pancreatitis incidence, and worsening acute pancreatitis severity. This review explores these associations, underlying mechanisms, and potential therapies.

RECENT FINDINGS

We review how the obesity associated increase in gallstones, surgical, and endoscopic interventions for obesity management, diabetes, and related medications such as incretin-based therapies and hypertriglyceridemia may increase the incidence of acute pancreatitis. The mechanism of how obesity may increase acute pancreatitis severity are discussed with a focus on cytokines, adipokines, damage-associated molecular patterns and unsaturated fatty acid-mediated lipotoxicity. The role of obesity in exacerbating pancreatic necrosis is discussed; focusing on obesity-associated pancreatic steatosis. We also discuss how peripancreatic fat necrosis worsens organ failure independent of pancreatic necrosis. Last, we discuss emerging therapies including choice of intravenous fluids and the use of lipase inhibitors which have shown promise during severe acute pancreatitis.

SUMMARY

We discuss how obesity may contribute to increasing acute pancreatitis incidence, the role of lipolytic unsaturated fatty acid release in worsening acute pancreatitis, and potential approaches, including appropriate fluid management and lipase inhibition in improving acute pancreatitis outcomes.

Anti-Inflammatory Effect of Anti-TNF-α SiRNA Cationic Phosphorus Dendrimer Nanocomplexes Administered Intranasally in a Murine Acute Lung Injury Model

Inflammation is an essential component of many lung diseases, including asthma, chronic obstructive pulmonary disease (COPD), or acute lung injury. Our purpose was to design efficient carriers for lung delivery of small interfering RNA (siRNA) targeting tumor necrosis factor (TNF-α) in an acute lung injury model. To achieve this goal, two different types of phosphorus-based dendrimers with either pyrrolidinium or morpholinium as terminal protonated amino groups were selected for their better biocompatibility compared to other dendrimers. Dendriplexes containing pyrrolidinium surface groups demonstrated a stronger siRNA complexation, a higher cellular uptake, and enhanced in vitro silencing efficiency of TNF-α in the lipopolysaccharide (LPS)-activated mouse macrophage cell line RAW264.7, compared to morpholinium-containing dendriplexes. The better performance of the pyrrolidium dendriplexes was attributed to their higher pK_a value leading to a stronger siRNA complexation and improved protection against enzymatic degradation resulting in a higher cellular uptake. The superior silencing effect of the pyrrolidinium dendriplexes, compared to noncomplexed siRNA, was confirmed in vivo in an LPS-induced murine model of short-term acute lung injury upon lung delivery via nasal administration. These data suggest that phosphorus dendriplexes have a strong potential in lung delivery of siRNA for treating inflammatory lung diseases.

Chloroquine attenuates paraquat-induced lung injury in mice by altering inflammation, oxidative stress and fibrosis

Paraquat is one of the most extensively used herbicides and has high toxicity for humans and animals. However, there is no effective treatment for paraquat poisoning. The aim of the present study was to evaluate the effects of chloroquine on paraquat-induced lung injury in mice. Mice received a single intraperitoneal injection of paraquat and a daily intraperitoneal injection of the indicated dosages of chloroquine or dexamethasone. The histological changes, inflammation and oxidative stress in the lungs were examined at day 3, and the degree of pulmonary fibrosis was examined at day 28. H&E staining showed that chloroquine markedly attenuated lung injury induced by paraquat. In addition, the inflammatory responses induced by paraquat were inhibited after treatment with chloroquine, as indicated by the decreased number of leukocytes, the reduced levels of TNF-α, IL-1β and IL-6 in the bronchoalveolar lavage fluid, the reduced NO content, and downregulation of iNOS expression in lung tissues. No different effect was found between high-dose chloroquine and dexamethasone. Additionally, the treatment with chloroquine increased the activity of SOD and decreased the level of MDA in the lung tissues. The expressions of the anti-oxidative proteins, Nrf2, HO-1 and NQO1, were also upregulated by chloroquine treatment. The high-dose chloroquine was more effective than dexamethasone in its anti-oxidation ability. Finally, the results of Masson's staining illustrated that chloroquine markedly attenuated fibrosis in the paraquat-exposed lungs. Immunohistochemistry staining showed that the expressions of the pro-fibrotic proteins TGF-β and α-SMA were downregulated after treatment with chloroquine. In conclusion, chloroquine effectively attenuated paraquat-induced lung injury in mice.

Interleukin-6 displays lung anti-inflammatory properties and exerts protective hemodynamic effects in a double-hit murine acute lung injury

Background

Interleukin 6 (IL-6) is a predictive factor of poor prognosis in patients with acute respiratory distress syndrome (ARDS). However, its acute pulmonary hemodynamic effects and role in lung injury have not been investigated in a clinically relevant murine model of ARDS.

Methods

We used adult C57Bl6 wild-type (WT) and IL-6 knock-out (IL-6KO) mice. The animals received intravenous recombinant human IL-6 (rHuIL-6) or vehicle followed by intratracheal lipopolysaccharide (LPS) or saline before undergoing low tidal volume mechanical ventilation (MV) for 5 h. Before sacrifice, right ventricular systolic pressure and cardiac output were measured and total pulmonary resistance was calculated. After sacrifice, lung inflammation, edema and injury were assessed with bronchoalveolar lavage (BAL) and histology. In other experiments, right ventricular systolic pressure was recorded during hypoxic challenges in uninjured WT mice pretreated with rHuIL-6 or rHuIL-6 + non-selective nitric oxide synthase inhibitor L-NAME or vehicle.

Results

IL-6KO_(LPS+MV) mice showed a faster deterioration of lung elastic properties and more severe bronchoalveolar cellular inflammation as compared to WT_(LPS+MV). Treatment with rHuIL-6 partially prevented this lung deterioration. Total pulmonary resistance was higher in IL-6KO_(LPS+MV) mice and this increase was abolished in rHuIL-6-treated IL-6KO mice. Finally, rHuIL-6 reduced hypoxic pulmonary vasoconstriction in uninjured WT mice, an effect that was abolished by co-treatment with L-NAME.

Conclusions

In a double-hit murine model of ARDS, IL-6 deficient mice experienced more severe bronchoalveolar cellular inflammation as compared to wild-type littermates. Furthermore, IL-6 deficiency caused marked acute pulmonary hypertension, which may be, at least partially, due to vasoactive mechanisms. A dysregulation of nitric oxide synthase may account for this observation, a hypothesis that will need to be investigated in future studies.

[Association between high-mobility group box 1 and neonatal respiratory distress syndrome]

OBJECTIVE

To study the association between serum level of high-mobility group box 1(HMGB1) and neonatal respiratory distress syndrome (NRDS).

METHODS

A total of 35 infants with NRDS and 35 normal neonates (control group) were enrolled. Peripheral venous blood samples were collected with 12-24 hours after birth. ELISA was used to measure the serum level of HMGB1.

RESULTS

The infants with mild and severe NRDS had a significantly higher serum level of HMGB1 than the control group (P<0.05). The infants with severe NRDS had a significantly higher serum level of HMGB1 than those with mild NRDS (P<0.05). The infants with NRDS who died had a significantly higher serum level of HMGB1 than those who survived (P<0.05). The receiver operating characteristic (ROC) curve showed that the optimal cut-off value for serum level of HMGB1 to predict NRDS was 625.3 pg/mL with an area under the ROC curve (AUC) of 0.846 (95%CI: 0.755-0.936), and the optimal cut-off value for serum level of HMGB1 to predict the death of infants with NRDS was 772.2 pg/mL with an AUC of 0.916 (95%CI: 0.813-1.000).

CONCLUSIONS

Infants with NRDS have a significant increase in the serum level of HMGB1, and the serum level of HMGB1 can well predict the development and prognosis of NRDS.

Circulating IL-6 upregulates IL-10 production in splenic CD4+ T cells and limits acute kidney injury-induced lung inflammation

Although it is well established that acute kidney injury (AKI) is a proinflammatory state, little is known about the endogenous counter-inflammatory response. IL-6 is traditionally considered a pro-inflammatory cytokine that is elevated in the serum in both human and murine AKI. However, IL-6 is known to have anti-inflammatory effects. Here we sought to investigate the role of IL-6 in the counter-inflammatory response after AKI, particularly in regard to the anti-inflammatory cytokine IL-10. Ischemic AKI was induced by bilateral renal pedicle clamping. IL-10-deficient mice had increased systemic and lung inflammation after AKI, demonstrating the role of IL-10 in limiting inflammation after AKI. We then sought to determine whether IL-6 mediates IL-10 production. Wild-type mice with AKI had a marked upregulation of splenic IL-10 that was absent in IL-6-deficient mice with AKI. In vitro, addition of IL-6 to splenocytes increased IL-10 production in CD4⁺ T cells, B cells, and macrophages. In vivo, CD4-deficient mice with AKI had reduced splenic IL-10 and increased lung myeloperoxidase activity. Thus, IL-6 directly increases IL-10 production and participates in the counter-inflammatory response after AKI.

Immunotherapeutic implications of IL-6 blockade for cytokine storm

IL-6 contributes to host defense against infections and tissue injuries. However, exaggerated, excessive synthesis of IL-6 while fighting environmental stress leads to an acute severe systemic inflammatory response known as ‘cytokine storm’, since high levels of IL-6 can activate the coagulation pathway and vascular endothelial cells but inhibit myocardial function. Remarkable beneficial effects of IL-6 blockade therapy using a humanized anti-IL-6 receptor antibody, tocilizumab were recently observed in patients with cytokine release syndrome complicated by T-cell engaged therapy. In this review we propose the possibility that IL-6 blockade may constitute a novel therapeutic strategy for other types of cytokine storm, such as the systemic inflammatory response syndrome including sepsis, macrophage activation syndrome and hemophagocytic lymphohistiocytosis.

Peripancreatic fat necrosis worsens acute pancreatitis independent of pancreatic necrosis via unsaturated fatty acids increased in human pancreatic necrosis collections

BACKGROUND AND AIMS

Peripancreatic fat necrosis occurs frequently in necrotising pancreatitis. Distinguishing markers from mediators of severe acute pancreatitis (SAP) is important since targeting mediators may improve outcomes. We evaluated potential agents in human pancreatic necrotic collections (NCs), pseudocysts (PCs) and pancreatic cystic neoplasms and used pancreatic acini, peripheral blood mononuclear cells (PBMC) and an acute pancreatitis (AP) model to determine SAP mediators.

METHODS

We measured acinar and PBMC injury induced by agents increased in NCs and PCs. Outcomes of caerulein pancreatitis were studied in lean rats coadministered interleukin (IL)-1β and keratinocyte chemoattractant/growth-regulated oncogene, triolein alone or with the lipase inhibitor orlistat.

RESULTS

NCs had higher fatty acids, IL-8 and IL-1β versus other fluids. Lipolysis of unsaturated triglyceride and resulting unsaturated fatty acids (UFA) oleic and linoleic acids induced necro-apoptosis at less than half the concentration in NCs but other agents did not do so at more than two times these concentrations. Cytokine coadministration resulted in higher pancreatic and lung inflammation than caerulein alone, but only triolein coadministration caused peripancreatic fat stranding, higher cytokines, UFAs, multisystem organ failure (MSOF) and mortality in 97% animals, which were prevented by orlistat.

CONCLUSIONS

UFAs, IL-1β and IL-8 are elevated in NCs. However, UFAs generated via peripancreatic fat lipolysis causes worse inflammation and MSOF, converting mild AP to SAP.