Macrophage-derived cytokines in pneumonia: Linking cellular immunology and genetics

Shufeng Jiedu capsule alleviates influenza A (H1N1) virus induced acute lung injury by regulating the lung inflammatory microenvironment

Background

Death caused by respiratory tract infection is one of the leading causes of death in the world today. Shufeng Jiedu Capsule (SFJDC) is a traditional Chinese medicine that has been widely used clinically for coronavirus disease 2019 (COVID-19), H1N1 influenza virus pneumonia and other diseases. Its pharmacological effect is to inhibit inflammation and improve the body's ability to clear viruses. However, the mechanism of SFJDC in the treatment of viral pneumonia, especially its effect on the inflammatory-immune microenvironment of lung tissue remains unclear.

Methods

Mice with H1N1 influenza virus pneumonia were used as a model to verify the efficacy of SFJDC through death protection, lung index, viral load, and HE staining of lung tissue. The levels of inflammatory cytokines and chemokines in lung tissue were investigated by multi-analyte immunoassay. The number and proportion of cells in peripheral blood were detected by blood routine. The percentage of infiltrating immune cells in lung tissue was detected by flow cytometry and immunofluorescence.

Results

SFJDC (2.2 g/kg·d-1 and 1.1 g/kg·d-1) increased survival rate (P＜0.01, P＜0.05), prolonged the survival period of mice, and alleviated the histopathological damage in lung (P＜0.01). SFJDC (2.2 g/kg·d-1, 1.1 g/kg·d-1 and 0.055 g/kg·d-1) increased body weight(P＜0.01, P＜0.05), improved activity status, reduced the lung index (P＜0.01, P＜0.05) and viral load (P＜0.01). SFJDC (2.2 g/kg·d-1 and 1.1 g/kg·d-1) reduced interleukin-1β (IL-1β), interleukin-18(IL-18), tumour necrosis factor α (TNF-α), monocyte chemoattractant protein (MCP), chemokine (C-X-C motif) ligand 1 (CXCL1) (P＜0.01, P＜0.05), and SFJDC (2.2 g/kg·d-1) increased IL-10 levels (P＜0.05) to regulate inflammation. SFJDC (2.2 g/kg·d-1) increased the percentages of CD4+ T cells (P＜0.01), CD8+ T cells (P＜0.05), and B cells(P＜0.05), and decreased F4/80+ macrophages (P＜0.05).

Conclusion

Our findings indicated that SFJDC could inhibit inflammation and lung injury while maintaining the function of the adaptive immune response mediated by T and B cells, and promote the clearance of the virus, thereby treating influenza A (H1N1) virus-induced pneumonia.

Efficacy and safety of carrimycin in ten patients with severe pneumonia following solid organ transplantation

BACKGROUND

The number of patients undergoing solid organ transplantation has increased annually. However, infections in solid organ transplant recipients can have a severe effect on patient survival owing to the continued use of immunosuppressants. Carrimycin is a novel macrolide antibiotic produced by genetically engineered streptomyces spiramyceticus harboring a 4''-O-isovaleryltransferase gene (ist) from streptomyces thermotoleran. Carrimycin has good antibacterial and antiviral effects. However, no relevant studies have been conducted on the efficacy and safety of carrimycin in patients with severe pneumonia (SP) after solid organ transplantation.

AIM

To explore the efficacy and safety of carrimycin in patients with SP after solid organ transplantation to provide a medication reference for clinical treatment.

METHODS

In March 2022, ten patients with SP following solid-organ transplantation were treated at our hospital between January 2021 and March 2022. When the condition was critical and difficult to control with other drugs, carrimycin was administered. These ten patients' clinical features and treatment protocols were retrospectively analyzed, and the efficacy and safety of carrimycin for treating SP following solid organ transplantation were evaluated.

RESULTS

All ten patients were included in the analysis. Regarding etiological agent detection, there were three cases of fungal pneumonia, two cases of bacterial pneumonia, two cases of Pneumocystis pneumonia, and three cases of mixed infections. After treatment with carrimycin, the disease in seven patients significantly improved, the course of the disease was significantly shortened, fever was quickly controlled, chest computed tomography was significantly improved, and oxygenation was significantly improved. Finally, the patients were discharged after curing. One patient died of acute respiratory distress syndrome, and two patients discontinued treatment.

CONCLUSION

Carrimycin is a safe and effective treatment modality for SP following solid organ transplantation. Carrimycin may have antibacterial and antiviral effects in patients with SP following solid organ transplantation.

Macrophage-Targeting DNA Nanomaterials: A Future Direction of Biological Therapy

DNA can be used for precise construction of complex and flexible micro-nanostructures, including DNA origami, frame nucleic acids, and DNA hydrogels. DNA nanomaterials have good biocompatibility and can enter macrophages via scavenger receptor-mediated endocytosis. DNA nanomaterials can be uniquely and flexibly designed to ensure efficient uptake by macrophages, which represents a novel strategy to regulate macrophage function. With the development of nanotechnology, major advances have been made in the design and manufacturing of DNA nanomaterials for clinical therapy. In diseases accompanied by macrophage disturbances including tumor, infectious diseases, arthritis, fibrosis, acute lung injury, and atherosclerosis, DNA nanomaterials received considerable attention as potential treatments. However, we lack sufficient information to guarantee precise targeting of macrophages by DNA nanomaterials, which precludes their therapeutic applications. In this review, we summarize recent studies of macrophage-targeting DNA nanomaterials and discuss the limitations and challenges of this approach with regard to its potential use as a biological therapy.

A living neutrophil Biorobot synergistically blocks multifaceted inflammatory pathways in macrophages to effectively neutralize cytokine storm

Cytokine storm is a potentially life-threatening immune response typically correlated with lung injury, particularly in people with underlying disease states, such as pneumonia. Therefore, the prompt treatment of cytokine storm is essential for successful recovery from a potentially fatal condition. Herein, a living anti-inflammatory Biorobot (firefighter), composed of neutrophils encapsulating mannose-decorated liposomes of the NF-κB inhibitor TPCA-1 and STING inhibitor H-151 (M-Lip@TH, inflammatory retardant), is developed for alleviating hyperinflammatory cytokine storm through targeting multiple inflammatory pathways in macrophages. Biorobot fully inherits the chemotaxis characteristics of neutrophils, and efficiently delivers and releases therapeutic M-Lip@TH at the inflammatory site. Subsequently, M-Lip@TH selectively targets macrophages and simultaneously blocks the transcription factor NF-κB pathway and STING pathway, thereby preventing the overproduction of cytokines. Animal studies show that Biorobot selectively targets LPS-induced acute lung injury, and not only inhibits the NF-κB pathway to suppress the release of various pro-inflammatory cytokines and chemokines, but also blocks the STING pathway to prevent an overactive immune response, which helps to neutralize cytokine storms. Particularly, Biorobot reduces lung inflammation and injury, improves lung function, and increases the survival rates of pneumonia mice. Therefore, Biorobot represents a rational combination therapy against cytokine storm, and may provide insights into the treatment of diseases involving overactive immune responses.

Age-Associated KLF9 Enhances the Inflammatory Response of Alveolar Macrophages Via Regulating TLR2 Expression

Staphylococcus aureus pneumonia is a severe infection in infant and young children. Toll-like receptor 2 (TLR2)-mediated inflammation plays essential roles in S. aureus pneumonia. Krueppel-like factor 9 (KLF9) is a transcriptional factor participating in multiple cellular aspects including inflammation. In this study, the potential roles of KLF9 in S. aureus pneumonia were evaluated. The expression of KLF9 in peripheral blood mononuclear cells (PBMCs) from healthy donors with different ages and in alveolar macrophages from mice with different ages was measured. Pam3CK4-induced expression of inflammatory cytokines was compared in alveolar macrophages from young and old mice and in wild-type (WT) and KLF9-deficient macrophages. The survival rate, body weight loss, lung pathology were compared between WT and KLF9-deficient mice after S. aureus infection. The TLR2 expression was compared between WT and KLF9-deficient macrophages after Pam3CK4 treatment. Decreased expression of KLF9 was detected in PBMCs from elder donor and in macrophages from old mice. Impaired expression of pro-inflammatory cytokines was observed in macrophages from old mice and KLF9-deficient macrophages after Pam3CK4 treatment. KLF9-deficient mice had elevated survival rate, decreased lung injury after S. aureus infection. Decreased expression of TLR2 was detected in KLF9-deficient macrophages and overexpression of TLR2 rescued the impaired expression of inflammatory cytokines in KLF9-deficient macrophages. KLF9 regulated inflammatory responses in macrophages through TLR2.

Identification of kynurenine and quinolinic acid as promising serum biomarkers for drug-induced interstitial lung diseases

BACKGROUND

Drug-induced interstitial lung disease (DILD) is a lung injury caused by various types of drugs and is a serious problem in both clinical practice and drug development. Clinical management of the condition would be improved if there were DILD-specific biomarkers available; this study aimed to meet that need.

METHODS

Biomarker candidates were identified by non-targeted metabolomics focusing on hydrophilic molecules, and further validated by targeted approaches using the serum of acute DILD patients, DILD recovery patients, DILD-tolerant patients, patients with other related lung diseases, and healthy controls.

RESULTS

Serum levels of kynurenine and quinolinic acid (and kynurenine/tryptophan ratio) were elevated significantly and specifically in acute DILD patients. The diagnostic potentials of these biomarkers were superior to those of conventional lung injury biomarkers, Krebs von den Lungen-6 and surfactant protein-D, in discriminating between acute DILD patients and patients with other lung diseases, including idiopathic interstitial pneumonia and lung diseases associated with connective tissue diseases. In addition to identifying and evaluating the biomarkers, our data showed that kynurenine/tryptophan ratios (an indicator of kynurenine pathway activation) were positively correlated with serum C-reactive protein concentrations in patients with DILD, suggesting the potential association between the generation of these biomarkers and inflammation. Our in vitro experiments demonstrated that macrophage differentiation and inflammatory stimulations typified by interferon gamma could activate the kynurenine pathway, resulting in enhanced kynurenine levels in the extracellular space in macrophage-like cell lines or lung endothelial cells. Extracellular quinolinic acid levels were elevated only in macrophage-like cells but not endothelial cells owing to the lower expression levels of metabolic enzymes converting kynurenine to quinolinic acid. These findings provide clues about the molecular mechanisms behind their specific elevation in the serum of acute DILD patients.

CONCLUSIONS

The serum concentrations of kynurenine and quinolinic acid as well as kynurenine/tryptophan ratios are promising and specific biomarkers for detecting and monitoring DILD and its recovery, which could facilitate accurate decisions for appropriate clinical management of patients with DILD.

Macrophage-derived inflammation promotes pulmonary vascular remodeling in hypoxia-induced pulmonary arterial hypertension mice

The role of inflammation in pulmonary hypertension is gradually gaining increasing research attention. However, no previous study has evaluated the characteristics of inflammation during chronic hypoxia-induced pulmonary hypertension. Therefore, the aim of this study was to investigate the characteristics of the inflammatory process involved in hypoxia-induced pulmonary hypertension in mice. The current study evaluated from day 4 to day 28 of hypoxia, the PAAT and PAAT/PET decreased, accompanied by pulmonary vascular remodeling and right ventricular hypertrophy, as well as increased numbers of CD68 macrophages. The expression of the pro-inflammatory factors IL-1β and IL-33 increased, but decreased on day 28. The expression of IL-12 increased from day 4 to day 28, whereas that of the anti-inflammatory factor IL-10 in lung tissue decreased. Furthermore, the expression of the IL-33/ST2 signaling pathway also increased over time under hypoxic conditions. In conclusion, pulmonary artery remodeling in HPH mice worsens progressively in a time-dependent manner, with inflammatory cell infiltration predominating in the early stage and pulmonary vascular remodeling occurring in the later stage.

Hydrogen Therapy and Its Future Prospects for Ameliorating COVID-19: Clinical Applications, Efficacy, and Modality

Molecular hydrogen is renowned as an odorless and colorless gas. The recommendations developed by China suggest that the inhalation of hydrogen molecules is currently advised in COVID-19 pneumonia treatment. The therapeutic effects of molecular hydrogens have been confirmed after numerous clinical trials and animal-model-based experiments, which have expounded that the low molecular weight of hydrogen enables it to easily diffuse and permeate through the cell membranes to produce a variety of biological impacts. A wide range of both chronic and acute inflammatory diseases, which may include sepsis, pancreatitis, respiratory disorders, autoimmune diseases, ischemia-reperfusion damages, etc. may be treated and prevented by using it. H₂ can primarily be inoculated through inhalation, by drinking water (which already contains H₂), or by administrating the injection of saline H₂ in the body. It may play a pivotal role as an antioxidant, in regulating the immune system, in anti-inflammatory activities (mitochondrial energy metabolism), and cell death (apoptosis, pyroptosis, and autophagy) by reducing the formation of excessive reactive O₂ species and modifying the transcription factors in the nuclei of the cells. However, the fundamental process of molecular hydrogen is still not entirely understood. Molecular hydrogen H₂ has a promising future in therapeutics based on its safety and possible usefulness. The current review emphasizes the antioxidative, anti-apoptotic, and anti-inflammatory effects of hydrogen molecules along with the underlying principle and fundamental mechanism involved, with a prime focus on the coronavirus disease of 2019 (COVID-19). This review will also provide strategies and recommendations for the therapeutic and medicinal applications of the hydrogen molecule.

Immunosuppressive dead cell as lung-targeting vehicle and cytokine absorption material for cytokine storm attenuation of pneumonia

Effectively controlling cytokine storm is important to reduce the mortality of severe pneumonia. In this work a bio-functional dead cell was engineered by one-time quick shock of live immune cells in liquid nitrogen, and the obtained immunosuppressive dead cell could server as both lung-targeting vehicle and cytokine absorption material. After loading the anti-inflammatory drugs of dexamethasone (DEX) and baicalin (BAI), the drug-loaded dead cell (DEX&BAI/Dead cell) could first passively target to the lung after intravenous administration and quickly release the drugs under high shearing stress of pulmonary capillaries, realizing drug enrichment in the lung. Then, the immunosuppressive dead cell acted as the camouflage of normal immune cells with various cytokine receptors exposing on their surface, to "capture" the cytokines and further reduce the state of inflammation. With above formulation design, a synergic anti-inflammatory effect between drugs and carrier could be achieved. In a lipopolysaccharide-induced pneumonia mice model, this system could calm down the cytokine storm with high efficacy and elongate the survival of mice.

Application Potential of Luteolin in the Treatment of Viral Pneumonia

Aim of the Review. This study aims to summarize the therapeutic effect of luteolin on the pathogenesis of viral pneumonia, explore its absorption and metabolism in the human body, evaluate the possibility of luteolin as a drug to treat viral pneumonia, and provide a reference for future research. Materials and Methods. We searched MEDLINE/PubMed, Web of Science, China National Knowledge Infrastructure, and Google Scholar and collected research on luteolin in the treatment of viral pneumonia and related diseases since 2003. Then, we summarized the efficacy and potential of luteolin in directly inhibiting viral activity, limiting inflammatory storms, reducing pulmonary inflammation, and treating pneumonia complications. Results and Conclusion. Luteolin has the potential to treat viral pneumonia in multiple ways. Luteolin has a direct inhibitory effect on coronavirus, influenza virus, and respiratory syncytial virus. Luteolin can alleviate the inflammatory factor storm induced by multiple factors by inhibiting the function of macrophages or mast cells. Luteolin can reduce pulmonary inflammation, pulmonary edema, or pulmonary fibrosis induced by multiple factors. In addition, viral pneumonia may cause multisystem complications, while luteolin has extensive protective effects on the gastrointestinal system, cardiovascular system, and nervous system. However, due to the first-pass metabolism mediated by phase II enzymes, the bioavailability of oral luteolin is low. The bioavailability of luteolin can be improved, and its potential value can be further developed by changing the dosage form or route of administration.

Fibroblast heterogeneity in pancreatic ductal adenocarcinoma: Perspectives in immunotherapy

Cancer-associated fibroblasts (CAFs), the key component in pancreatic tumor microenvironment (TME), originate from many sources and are naturally heterogeneous in phenotype and function. Numerous studies have identified their crucial role in promoting tumorigenesis through many routes including fostering cancer proliferation, angiogenesis, invasion, and metastasis. Conversely, research also indicates that subsets of CAFs express anti-tumor activity. These dual effects reflect the complexity of CAF heterogeneity and their interactions with other cells and factors in pancreatic TME. A critical component in this environment is infiltrated immune cells and immune mediators, which can communicate with CAFs. The crosstalk occurs via the production of various cytokines, chemokines, and other mediators and shapes the immunological state in TME. Comprehensive studies of the crosstalk between CAFs and tumor immune environment, particularly internal mechanisms interlinking CAFs and immune effectors, may provide new approaches for pancreatic ductal adenocarcinoma (PDAC) treatments. In this review, we explore the characteristics of CAFs, describe the interplay among CAFs, infiltrated immune cells, other mediators, and provide an overview of recent CAF-target therapies, their limitations, and potential research directions in CAF in the context of PDAC.

Lignans from Mosla scabra Ameliorated Influenza A Virus-Induced Pneumonia via Inhibiting Macrophage Activation

The lower respiratory tract infection, induced by influenza virus, coronaviruses, and respiratory syncytial virus, remains a serious threat to human health that can cause a global pandemic. Thus, finding effective chemicals and therapeutic measures to advance the functional restoration of the respiratory tract after infection has been the emphasis of the studies on the subjects. Mosla scabra is a natural medicinal plant used for treating various lung and gastrointestinal diseases, including viral infection, cough, chronic obstructive pulmonary disease, acute gastroenteritis, and diarrhoea. In this study, the antiviral and anti-inflammatory effects of total lignans (MSTL) extracted from the plant were investigated in influenza A virus (IAV)-infected mice and RAW 264.7 macrophages. MSTL could not only protect the macrophages against IAV-induced pyroptosis but also could lighten the lung inflammation induced by IAV in vivo and in vitro. The network pharmacology analysis revealed that differentially expressed genes, mainly involving in EGFR tyrosine kinase inhibitor resistance, endocrine resistance, HIF-1 signaling pathway, C-type lectin receptor signaling pathway, and FOXO signaling pathway, contributed to the IAV-induced alveolar macrophage dysfunction. It indicated that MSTL enhanced the function of alveolar macrophages and improved IAV-induced lung injury in mice.

Liposomal Dexamethasone Reduces A/H1N1 Influenza-Associated Morbidity in Mice

Re-emerging viral threats have continued to challenge the medical and public health systems. It has become clear that a significant number of severe viral infection cases are due to an overreaction of the immune system, which leads to hyperinflammation. In this study, we aimed to demonstrate the therapeutic efficacy of the dexamethasone nanomedicine in controlling the symptoms of influenza virus infection. We found that the A/Wisconsin/WSLH34939/2009 (H1N1) infection induced severe pneumonia in mice with a death rate of 80%, accompanied by significant epithelial cell damage, infiltration of immune cells, and accumulation of pro-inflammatory cytokines in the airway space. Moreover, the intranasal delivery of liposomal dexamethasone during disease progression reduced the death rate by 20%. It also significantly reduced the protein level of tumor necrosis factor-alpha (TNFα), interleukin-1β (IL-1β), IL-6, and the C-X-C motif chemokine ligand 2 (CXCL2) as well as the number of infiltrated immune cells in the bronchoalveolar lavage fluids as compared to the control and free dexamethasone. The liposomal dexamethasone was mainly distributed into the monocyte/macrophages as a major cell population for inducing the cytokine storm in the lungs. Taken together, the intranasal delivery of liposomal dexamethasone may serve as a novel promising therapeutic strategy for the treatment of influenza A-induced pneumonia.

The Association between Regulatory T Cell Subpopulations and Severe Pneumonia Post Renal Transplantation

Severe pneumonia accounts for the majority of morbidity and mortality in renal allograft recipients due to immunosuppressant maintenance. Regulatory T cells (Tregs), which are involved in tackling infections under immunosuppressive conditions, are rarely uncovered. We aimed to investigate the relationship between various Treg subpopulations and severe pneumonia after kidney transplantation (KTx). KTx recipients with pneumonia were divided into severe pneumonia and mild pneumonia groups. The frequencies and absolute numbers (Ab No.) of total Tregs (CD4+CD25+FoxP3+), six subsets of Tregs (Helios+/-, CD39+/-, and CD45RA+/-), and T cells, B cells, and NK cells were assessed from peripheral blood via flow cytometry using the $t$ or Mann-Whitney test and receiver operating curve analysis. We also determined the median fluorescence intensity (MFI) of human leukocyte antigen- (HLA-) DR on monocytes and CD64 on neutrophils. Logistic regression was used to identify the risk factors of disease progression, and Pearson’s correlation analysis was performed to identify relationships between the measured immune indices and patients’ clinical information. Our research indicated that Treg subpopulations were strongly associated with severe pneumonia progression post KTx. Based on the monitoring of Treg subpopulations, better-individualized prevention and therapy might be achieved for patients with severe pneumonia post KTx.

Extracellular HSPs: The Potential Target for Human Disease Therapy

Heat shock proteins (HSPs) are highly conserved stress proteins known as molecular chaperones, which are considered to be cytoplasmic proteins with functions restricted to the intracellular compartment, such as the cytoplasm or cellular organelles. However, an increasing number of observations have shown that HSPs can also be released into the extracellular matrix and can play important roles in the modulation of inflammation and immune responses. Recent studies have demonstrated that extracellular HSPs (eHSPs) were involved in many human diseases, such as cancers, neurodegenerative diseases, and kidney diseases, which are all diseases that are closely linked to inflammation and immunity. In this review, we describe the types of eHSPs, discuss the mechanisms of eHSPs secretion, and then highlight their functions in the modulation of inflammation and immune responses. Finally, we take cancer as an example and discuss the possibility of targeting eHSPs for human disease therapy. A broader understanding of the function of eHSPs in development and progression of human disease is essential for developing new strategies to treat many human diseases that are critically related to inflammation and immunity.

Targeting ectromelia virus and TNF/NF-κB or STAT3 signaling for effective treatment of viral pneumonia

Viral causes of pneumonia pose constant threats to global public health, but there are no specific treatments currently available for the condition. Antivirals are ineffective when administered late after the onset of symptoms. Pneumonia is caused by an exaggerated inflammatory cytokine response to infection, but tissue necrosis and damage caused by virus also contribute to lung pathology. We hypothesized that viral pneumonia can be treated effectively if both virus and inflammation are simultaneously targeted. Combined treatment with the antiviral drug cidofovir and etanercept, which targets tumor necrosis factor (TNF), down-regulated nuclear factor kappa B-signaling and effectively reduced morbidity and mortality during respiratory ectromelia virus (ECTV) infection in mice even when treatment was initiated after onset of clinical signs. Treatment with cidofovir alone reduced viral load, but animals died from severe lung pathology. Treatment with etanercept had no effect on viral load but diminished levels of inflammatory cytokines and chemokines including TNF, IL-6, IL-1β, IL-12p40, TGF-β, and CCL5 and dampened activation of the STAT3 cytokine-signaling pathway, which transduces signals from multiple cytokines implicated in lung pathology. Consequently, combined treatment with a STAT3 inhibitor and cidofovir was effective in improving clinical disease and lung pathology in ECTV-infected mice. Thus, the simultaneous targeting of virus and a specific inflammatory cytokine or cytokine-signaling pathway is effective in the treatment of pneumonia. This approach might be applicable to pneumonia caused by emerging and re-emerging viruses, like seasonal and pandemic influenza A virus strains and severe acute respiratory syndrome coronavirus 2.

Immunomodulatory activity of egg yolk protein hydrolysates prepared by novel two-step hydrolysis: A study of mechanism and stability after in vitro digestion model

The aim of this study was to determine the immunomodulatory activity of 2-step egg yolk protein hydrolysates. A two-step hydrolysate of egg yolk protein was prepared using 2 enzymes sequentially, pancreatin and neutrase (EYPH-PN). Our results illustrated that EYPH-PN increased the expression of inducible nitric oxide synthase (iNOS) mRNA in macrophages, resulting in increased nitric oxide (NO) production. EYPH-PN could also enhance the production of tumor necrosis factor (TNF)-α and interleukin (IL)-6 at both the mRNA and protein levels in macrophages. In addition, treatment with EYPH-PN increased the phagocytic activity of macrophages. According to the evaluation with specific inhibitors, both p38 and JNK cell signaling pathways were involved in the activation of macrophages induced by EYPH-PN. As the TLR-2 receptor of macrophages was blocked, the NO production induced by EYPH-PN was decreased. These results suggest that EYPH-PN activates RAW 264.7 macrophages via the TLR-2/p38/JNK pathway to increase the production of NO, TNF-α, and IL-6, and increases phagocytic activity. Furthermore, the immunomodulatory activity of EYPH-PN was maintained even after applying the in vitro digestion model. Taken together, EYPH-PN could be used as a functional food ingredient with excellent immunomodulatory activity in the food industry. Therefore, this study suggests a new alternative method to effectively utilize egg yolk protein, a by-product of the poultry industry.

Hydrogen, a Novel Therapeutic Molecule, Regulates Oxidative Stress, Inflammation, and Apoptosis

Molecular hydrogen (H₂) is a colorless and odorless gas. Studies have shown that H₂ inhalation has the therapeutic effects in many animal studies and clinical trials, and its application is recommended in the novel coronavirus pneumonia treatment guidelines in China recently. H₂ has a relatively small molecular mass, which helps it quickly spread and penetrate cell membranes to exert a wide range of biological effects. It may play a role in the treatment and prevention of a variety of acute and chronic inflammatory diseases, such as acute pancreatitis, sepsis, respiratory disease, ischemia reperfusion injury diseases, autoimmunity diseases, etc.. H₂ is primarily administered via inhalation, drinking H₂-rich water, or injection of H₂ saline. It may participate in the anti-inflammatory and antioxidant activity (mitochondrial energy metabolism), immune system regulation, and cell death (apoptosis, autophagy, and pyroptosis) through annihilating excess reactive oxygen species production and modulating nuclear transcription factor. However, the underlying mechanism of H₂ has not yet been fully revealed. Owing to its safety and potential efficacy, H₂ has a promising potential for clinical use against many diseases. This review will demonstrate the role of H₂ in antioxidative, anti-inflammatory, and antiapoptotic effects and its underlying mechanism, particularly in coronavirus disease-2019 (COVID-19), providing strategies for the medical application of H₂ for various diseases.