Down-regulation of hsa_circ_0045474 induces macrophage autophagy in tuberculosis via miR-582-5p/TNKS2 axis

Macrophage autophagy plays a major role in the control and elimination of invading Mycobacterium tuberculosis. However, the function and mechanism of circRNA on macrophage autophagy in tuberculosis remain unclear. Therefore, this study aimed to explore the role of circRNA underlying macrophage autophagy in tuberculosis. Quantitative real-time polymerase chain reaction was used to detect the expression of hsa_circ_0045474, miR-582-5p and TNKS2. Autophagy was detected by LC3B immunofluorescence and transmission electron microscopy. Dual-luciferase reporter assays were used to detect the relationship of miR-582-5p and hsa_circ_0045474 or TNKS2. Western blot was used to detect the expression of LC3-І and LC3-ІІ. The results showed that hsa_circ_0045474 was down-regulated in monocytes from patients with tuberculosis and induced autophagy in macrophages. hsa_circ_0045474 sponged miR-582-5p and negatively regulated miR-582-5p expression. Overexpression of miR-582-5p affected by hsa_circ_0045474 induced autophagy in macrophages. TNKS2 served as a target of miR-582-5p and down-regulation of TNKS2 induced autophagy in macrophages regulated by miR-582-5p. In conclusion, our results demonstrated that hsa_circ_0045474 down-regulation induced macrophage autophagy in tuberculosis via miR-582-5p/ TNKS2 axis, implying a novel strategy to treat the occurrence of active pulmonary tuberculosis caused by immune escape of M. tuberculosis.

Bergamottin alleviates LPS-induced acute lung injury by inducing SIRT1 and suppressing NF-κB

Acute lung injury (ALI) is associated with a high mortality due to inflammatory cell infiltration and lung edema. The development of ALI commonly involves the activation of NF-κB. Since bergamottin is a natural furanocoumarin showing the ability to inhibit the activation of NF-κB, in this study we aimed to determine the effect of bergamottin on ALI. RAW264.7 mouse macrophages were pre-treated with bergamottin and then stimulated with LPS. Macrophage inflammatory responses were examined. Bergamottin (50 mg/kg body mass) was intraperitoneally administrated to mice 12 h before injection of LPS, and the effect of bergamottin on LPS-induced ALI was evaluated. Our results showed that LPS exposure led to increased production of TNF-α, IL-6, and monocyte chemoattractant protein-1 (MCP-1), which was impaired by bergamottin pre-treatment. In vivo studies confirmed that bergamottin pre-treatment suppressed LPS-induced lung inflammation and edema and reduced the levels of pro-inflammatory cytokines in lung tissues and bronchoalveolar lavage fluids. Mechanistically, bergamottin blocked LPS-induced activation of NF-κB signaling in lung tissues. Additionally, bergamottin treatment reduced NF-κB p65 protein acetylation, which was coupled with induction of SIRT1 expression. In conclusion, our results reveal the anti-inflammatory property of bergamottin in preventing ALI. Induction of SIRT1 and inhibition of NF-κB underlies the anti-inflammatory activity of bergamottin.

TLRs in COVID-19: How they drive immunopathology and the rationale for modulation

COVID-19 is both a viral illness and a disease of immunopathology. Proximal events within the innate immune system drive the balance between deleterious inflammation and viral clearance. We hypothesize that a divergence between the generation of excessive inflammation through over activation of the TLR associated myeloid differentiation primary response (MyD88) pathway relative to the TIR-domain-containing adaptor-inducing IFN-β (TRIF) pathway plays a key role in COVID-19 severity. Both viral elements and damage associated host molecules act as TLR ligands in this process. In this review, we detail the mechanism for this imbalance in COVID-19 based on available evidence, and we discuss how modulation of critical elements may be important in reducing severity of disease.

Chrysosplenol D protects mice against LPS-induced acute lung injury by inhibiting oxidative stress, inflammation, and apoptosis via TLR4-MAPKs/NF-κB signaling pathways

This study investigated the effect and mechanism of chrysosplenol D (CD) on LPS-induced acute lung injury in mice. Histological changes in the lungs were measured by hematoxylin-eosin staining. The levels of IL-6, IL-1β, and TNF-α in the bronchoalveolar lavage fluid were detected by ELISA. The levels of oxidative stress were detected by the cuvette assay. Immune cells in peripheral blood, the levels of reactive oxygen species, and apoptosis of primary lung cells were detected by flow cytometry. The mRNA levels of TLR4, MyD88, IL-1β, and NLRP3 were measured by quantitative real-time polymerase chain reaction. The levels of proteins in apoptosis and the TLR4-MAPKs/NF-κB signaling pathways were detected by Western blot. Hematoxylin-eosin staining showed that CD could improve lung injury; decrease the levels of inflammatory factors, oxidative stress, reactive oxygen species, and cell apoptosis; and regulate the immune system. Moreover, CD could down-regulate the mRNA levels of TLR4, MyD88, NLRP3, and IL-1β in lung, and the protein levels of Keap-1, Cleaved-Caspase-3/Caspase-3, Cleaved-Caspase-9/Caspase-9, TLR4, MyD88, p-ERK/ERK, p-JNK/JNK, p-p38/p38, p-p65/p65, NLRP3, and IL-1β, and up-regulated the levels of Bcl-2/Bax, p-Nrf2/Nrf2, and HO-1. The results suggested that CD could protect mice against LPS-induced acute lung injury by inhibiting oxidative stress, inflammation, and apoptosis via the TLR4-MAPKs/NF-κB signaling pathways.

Enteral nutrition ameliorates the symptoms of Crohn's disease in mice via activating special pro-resolving mediators through innate lymphoid cells

Crohn's disease activates the inflammatory reactions to induce intestinal disorders. Enteral nutrition (EN) could exert general immunomodulatory effects. Cecal ligation and perforation (CLP) surgery was utilized to establish Crohn's disease mice models. Survival analysis, hematoxylin-eosin staining, flow cytometry, ELISA, Western blot and liquid chromatography-tandem MS were applied. Baicalein was added to inhibit lipoxygenases. The survival rate was restored and inflammatory injury, exudate neutrophils in peritoneal lavage and serum levels of IL-6 and TNF-α were ameliorated by EN treatment as compared with CLP treatment. EN also increased ILC-3 content, 5/15-LOX level and RvD1-RvD5 in peritoneal lavage. Baicalein reversed all the detected effects of EN except ILC-3 content. EN could activate special pro-resolving mediators (SPMs) through ILCs to mitigate injuries of Crohn's disease.

Circulating innate lymphoid cell subtypes and altered cytokine profiles following an atherogenic high-fat diet

Impaired Glc tolerance and hyperinsulinemia are a hallmark of type 2 diabetes (T2D) and are associated with an altered innate and adaptive immune response. In this study, we used a high-fat diet (HFD)-induced model of pre-diabetes to explore the pathological implications of altered innate lymphoid cell (ILC) profiles in a state of impaired Glc tolerance. Sixteen male C57BL/6 mice were randomized to receive two experimental diets ( n = 8 per group), low-fat (LFD), and HFD for 8–13 wk. We evaluated the levels of circulating innate lymphoid cells and their respective cytokines following HFD-feeding. The HFD group had impaired Glc tolerance, elevated insulin levels, and increased total cholesterol levels. Notably, the levels of circulating ILC1s were elevated following 13 wk of HFD-feeding. Moreover, the levels of TNF-α were decreased, but there were no changes in IFN-γ levels. Lastly, the levels of circulating ILC2s and ILC3s were comparable between the HFD and LFD group. The findings demonstrated that short-term HFD-feeding increases postprandial blood Glc, total cholesterol and insulin levels. However, the metabolic changes did not alter ILC2 and ILC3 levels and their respective cytokine profiles.

Wolf–Hirschhorn syndrome candidate 1 facilitates alveolar macrophage pyroptosis in sepsis-induced acute lung injury through NEK7-mediated NLRP3 inflammasome activation

Sepsis is a complex clinical syndrome with high incidence and mortality. Acute lung injury (ALI) is a common complication of sepsis. At present, there is no effective therapeutic strategy to treat ALI. The SET domain–containing histone methyltransferase Wolf–Hirschhorn syndrome candidate 1 (WHSC1) regulates cancer progression, while its role in sepsis-induced ALI remains unclear. Thus, this study aimed to study the effect of WHSC1 on sepsis-induced ALI and to explore the potential mechanism of action. In the study, LPS treatment induced lung injury. WHSC1 was highly expressed in LPS-induced ALI. Knockdown of WHSC1 attenuated LPS-induced ALI and pyroptosis in vivo. Besides, knockdown of WHSC1 attenuated LPS-induced alveolar macrophage pyroptosis in vitro. Furthermore, NIMA-related kinase-7 (NEK7) expression could be regulated by WHSC1, and NEK7 bound to NLRP3 in alveolar macrophages. Moreover, WHSC1 regulated alveolar macrophage pyroptosis through modulating NEK7-mediated NLRP3 inflammasome activation. In conclusion, WHSC1 was highly expressed in LPS-induced ALI. WHSC1 facilitated alveolar macrophage pyroptosis in sepsis-induced ALI through NEK7-mediated NLRP3 inflammasome activation. WHSC1 may be a valuable target for the therapy of sepsis-induced ALI.

Effects of fatty acid nitroalkanes on signal transduction pathways and airway macrophage activation

Fatty acid nitroalkenes are reversibly-reactive electrophiles that are endogenously detectable at nM concentrations and display anti-inflammatory, pro-survival actions. These actions are elicited through the alteration of signal transduction proteins via a Michael addition on nucleophilic cysteine thiols. Nitrated fatty acids (NO2-FAs), like 9- or 10-nitro-octadec-9-enolic acid, will act on signal transduction proteins directly or on key regulatory proteins to cause an up-regulation or down-regulation of the protein’s expression, yielding an anti-inflammatory response. These responses have been characterized in many organ systems, such as the cardiovascular system, with the pulmonary system less well defined. Macrophages are one of the most abundant immune cells in the lung and are essential in maintaining lung homeostasis. Despite this, macrophages can play a role in both acute and chronic lung injury due to up-regulation of anti-inflammatory signal transduction pathways and down-regulation of pro-inflammatory pathways. Through their propensity to alter signal transduction pathways, NO2-FAs may be able to reduce macrophage activation during pulmonary injury. This review will focus on the implications of NO2-FAs on macrophage activation in the lung and the signal transduction pathways that may be altered, leading to reduced pulmonary injury.

Long non-coding RNA ZFAS1 alleviates sepsis-induced myocardial injury via target miR-34b-5p/SIRT1

Long non-coding RNA ZFAS1 is down-regulated in sepsis. However, whether ZFAS1 participates in sepsis-induced cardiomyopathy (SIC) remains largely unknown. LPS injection to rats was used to establish an in vivo sepsis model, while LPS stimulation with H9C2 cell was used to mimic an in vitro sepsis-induced myocardial injury model. Western blots and quantitative RT-PCR were performed to evaluate protein and mRNA levels, respectively. ELISA was conducted to determine cytokine levels in supernatant. Flow cytometry was used to test apoptosis. Dual-luciferase assay was performed to validate binding between ZFAS1 and miR-34b-5p, miR-34b-5p and SIRT1. Our data revealed that ZFAS1 and SIRT1 were down-regulated, while miR-34b-5p was up-regulated in LPS-induced H9C2 cells. Inhibition of miR-34b-5p or overexpression of ZFAS1 alleviated inflammatory response and cell apoptosis in LPS-stimulated H9C2 cells. A mechanism study revealed that ZFAS1 sponged miR-34b-5p and thus elevated expression of SIRT1, which was prohibited by miR-34b-5p. ZFAS1 alleviated inflammatory response and cell apoptosis in LPS-stimulated H9C2 cells via the miR-34b-5p/SIRT1 axis, providing novel potential therapeutic targets for SIC.

Neglected roles of IgG Fc-binding protein secreted from airway mucin-producing cells in protecting against SARS-CoV-2 infection

Both innate immunity and acquired immunity are involved in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. The induction of Abs that neutralize the virus has been described, and certain Abs against endemic coronaviruses may cross-react with SARS-CoV-2. Detailed mechanisms to protect against the pandemic of SARS-CoV-2 remain unresolved. We previously reported that IgG Fc-binding protein (Fcγbp), a unique, large molecular weight, and mucin-like secretory Fc receptor protein, secreted from goblet cells of human small and large intestine, mediates the transportation of serum IgG onto the mucosal surface. In this review, we show that mucous bronchial gland cells and some goblet cells are immunoreactive for Fcγbp. Fcγbp traps the cross-reactive (both neutralizing and non-neutralizing) IgG bound to the virus and can consequently eliminate the virus from the mucosal surface to decrease viral loads. Fcγbp can also suppress immune overreaction by interfering with Fc-binding by macrophages and competing with complement fixation. Fcγbp secreted from mucin-producing cells of the airway functions as an important anti-infection mucosal defense. The Fcγbp-mediated mechanism can be a key factor in explaining why SARS-CoV-2 is less infective/lethal in children, and may also be involved in the unique Ab response, recurrent infection, and effects of serum therapy and vaccination.