GM-CSF-based treatments in COVID-19: reconciling opposing therapeutic approaches

Interplay between pulmonary epithelial stem cells and innate immune cells contribute to the repair and regeneration of ALI/ARDS

Mammalian lung is the important organ for ventilation and exchange of air and blood. Fresh air and venous blood are constantly delivered through the airway and vascular tree to the alveolus. Based on this, the airways and alveolis are persistently exposed to the external environment and are easily suffered from toxins, irritants and pathogens. For example, acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is a common cause of respiratory failure in critical patients, whose typical pathological characters are diffuse epithelial and endothelial damage resulting in excessive accumulation of inflammatory fluid in the alveolar cavity. The supportive treatment is the main current treatment for ALI/ARDS with the lack of targeted effective treatment strategies. However, ALI/ARDS needs more targeted treatment measures. Therefore, it is extremely urgent to understand the cellular and molecular mechanisms that maintain alveolar epithelial barrier and airway integrity. Previous researches have shown that the lung epithelial cells with tissue stem cell function have the ability to repair and regenerate after injury. Also, it is able to regulate the phenotype and function of innate immune cells involving in regeneration of tissue repair. Meanwhile, we emphasize that interaction between the lung epithelial cells and innate immune cells is more supportive to repair and regenerate in the lung epithelium following acute lung injury. We reviewed the recent advances in injury and repair of lung epithelial stem cells and innate immune cells in ALI/ARDS, concentrating on alveolar type 2 cells and alveolar macrophages and their contribution to post-injury repair behavior of ALI/ARDS through the latest potential molecular communication mechanisms. This will help to develop new research strategies and therapeutic targets for ALI/ARDS.

Revisiting the dimensions of universal vaccine with special focus on COVID-19: Efficacy versus methods of designing

Even though the use of SARS-CoV-2 vaccines during the COVID-19 pandemic showed unprecedented success in a short time, it also exposed a flaw in the current vaccine design strategy to offer broad protection against emerging variants of concern. However, developing broad-spectrum vaccines is still a challenge for immunologists. The development of universal vaccines against emerging pathogens and their variants appears to be a practical solution to mitigate the economic and physical effects of the pandemic on society. Very few reports are available to explain the basic concept of universal vaccine design and development. This review provides an overview of the innate and adaptive immune responses generated against vaccination and essential insight into immune mechanisms helpful in designing universal vaccines targeting influenza viruses and coronaviruses. In addition, the characteristics, safety, and factors affecting the efficacy of universal vaccines have been discussed. Furthermore, several advancements in methods worthy of designing universal vaccines are described, including chimeric immunogens, heterologous prime-boost vaccines, reverse vaccinology, structure-based antigen design, pan-reactive antibody vaccines, conserved neutralizing epitope-based vaccines, mosaic nanoparticle-based vaccines, etc. In addition to the several advantages, significant potential constraints, such as defocusing the immune response and subdominance, are also discussed.

High mortality of Acinetobacter baumannii infection is attributed to macrophage-mediated induction of cytokine storm but preventable by naproxen

BACKGROUND

The continuous emergence of multidrug-resistant (MDR) Acinetobacter baumannii (Ab) strains poses further challenges in its control and clinical management. It is necessary to decipher the mechanisms underlying the high mortality of Ab infections to explore unconventional strategies for controlling outbreaks of drug-resistant infections.

METHODS

The immune responses of Ab sepsis infection were investigated using flow cytometry, RNA-seq, qRT-PCR, and ELISA and scRNA-seq. The detailed pathways mediating Ab immune responses were also depicted and a specific therapy was developed based on the understanding of the mechanisms underlying Ab-induced cytokine storms.

FINDINGS

The results highlighted the critical role of alveolar and interstitial macrophages as targets of Ab during the infection process. These cells were found to undergo polarization towards the M1 phenotype, triggering a cytokine storm that eventually caused the death of the host. The polarization and excessive inflammatory response mediated by macrophages were mainly regulated by the TLR2/Myd88/NF-κB signaling pathway. Suppression of Ab-triggered inflammatory responses and M1 polarization by the drug naproxen (NPXS) was shown to confer full protection of mice from lethal infections.

INTERPRETATION

The findings in this work depict the major mechanisms underlying the high mortality rate of Ab infections and highlight the clinical potential application of anti-inflammatory drugs or immunosuppressants in reducing the mortality of such infections, including those caused by MDR strains.

FUNDING

Funding sources are described in the acknowledgments section.

Pyroptosis inhibition alleviates acute lung injury via E-twenty-six variant gene 5-mediated downregulation of gasdermin D

BACKGROUND

Acute lung injury (ALI) is a life-threatening condition characterized by excessive pulmonary inflammation, yet its precise pathophysiology remains elusive. Pyroptosis, a programmed cell death mechanism controlled by gasdermin D (GSDMD), has been linked to the etiology of ALI. This study investigated the regulatory functions of the transcription factor E-twenty-six variant gene 5 (ETV5) and GSDMD in ALI.

METHODS

Lipopolysaccharide (LPS) was used to treat BEAS-2B cells (50 mmol/mL) and establish an LPS-induced mouse model of ALI (by intratracheal administration, 3 mg/kg). Protein-protein docking, immunofluorescence analysis, western blotting, real-time quantitative polymerase chain reaction, and dual-luciferase reporter gene assay were used to examine ETV5-mediated negative feedback regulation of GSDMD and its effects on pyroptosis and ALI.

RESULTS

Our results showed that the physiological function of ETV5 was reduced by its downregulated expression, which impeded its nuclear translocation in ALI mice. Increased pyroptosis and enhanced production of inflammatory cytokines were associated with LPS-induced ALI. ETV5 overexpression in LPS-treated BEAS-2B cells decreased the expression of total and membrane-bound GSDMD, negatively regulated GSDMD, and prevented pyroptosis. The expression of inflammatory cytokines was subsequently reduced due to this inhibition, which, in turn, reduced ALI. Molecular docking analysis and dual-luciferase reporter gene assay results indicated a direct interaction between ETV5 and GSDMD, which inhibited GSDMD production.

CONCLUSION

Our results indicate that ETV5 inhibits pyroptosis, decreases the expression of inflammatory cytokines, and negatively regulates GSDMD expression to ameliorate ALI symptoms.

Clinic-oriented injectable smart material for the treatment of diabetic wounds: Coordinating the release of GM-CSF and VEGF

Chronic wounds are often caused by diabetes and present a challenging clinical problem due to vascular problems leading to ischemia. This inhibits proper wound healing by delaying inflammatory responses and angiogenesis. To address this problem, we have developed injectable particle-loaded hydrogels which sequentially release Granulocyte-macrophage- colony-stimulating-factor (GM-CSF) and Vascular endothelial growth factor (VEGF) encapsulated in polycaprolactone-lecithin-geleol mono-diglyceride hybrid particles. GM-CSF promotes inflammation, while VEGF facilitates angiogenesis. The hybrid particles (200-1000 nm) designed within the scope of the study can encapsulate the model proteins Bovine Serum Albumin 65 ± 5 % and Lysozyme 77 ± 10 % and can release stably for 21 days. In vivo tests and histological findings revealed that in the hydrogels containing GM-CSF/VEGF-loaded hybrid particles, wound depth decreased, inflammation phase increased, and fibrotic scar tissue decreased, while mature granulation tissue was formed on day 10. These findings confirm that the hybrid particles first initiate the inflammation phase by delivering GM-CSF, followed by VEGF, increasing the number of vascularization and thus increasing the healing rate of wounds. We emphasize the importance of multi-component and sequential release in wound healing and propose a unifying therapeutic strategy to sequentially deliver ligands targeting wound healing stages, which is very important in the treatment of the diabetic wounds.

Compartmentalization of the inflammatory response during bacterial sepsis and severe COVID-19

Acute infections cause local and systemic disorders which can lead in the most severe forms to multi-organ failure and eventually to death. The host response to infection encompasses a large spectrum of reactions with a concomitant activation of the so-called inflammatory response aimed at fighting the infectious agent and removing damaged tissues or cells, and the anti-inflammatory response aimed at controlling inflammation and initiating the healing process. Fine-tuning at the local and systemic levels is key to preventing local and remote injury due to immune system activation. Thus, during bacterial sepsis and Coronavirus disease 2019 (COVID-19), concomitant systemic and compartmentalized pro-inflammatory and compensatory anti-inflammatory responses are occurring. Immune cells (e.g., macrophages, neutrophils, natural killer cells, and T-lymphocytes), as well as endothelial cells, differ from one compartment to another and contribute to specific organ responses to sterile and microbial insult. Furthermore, tissue-specific microbiota influences the local and systemic response. A better understanding of the tissue-specific immune status, the organ immunity crosstalk, and the role of specific mediators during sepsis and COVID-19 can foster the development of more accurate biomarkers for better diagnosis and prognosis and help to define appropriate host-targeted treatments and vaccines in the context of precision medicine.

Immunotherapeutic implications on targeting the cytokines produced in rhinovirus-induced immunoreactions

Rhinovirus is a widespread virus associated with several respiratory diseases, especially asthma exacerbation. Currently, there are no accurate therapies for rhinovirus. Encouragingly, it is found that during rhinovirus-induced immunoreactions the levels of certain cytokines in patients' serum will alter. These cytokines may have pivotal pro-inflammatory or anti-inflammatory effects via their specific mechanisms. Thus far, studies have shown that inhibitions of cytokines such as IL-1, IL-4, IL-5, IL-6, IL-13, IL-18, IL-25, and IL-33 may attenuate rhinovirus-induced immunoreactions, thereby relieving rhinovirus infection. Furthermore, such therapeutics for rhinovirus infection can be applied to viruses of other species, with certain practicability.

In Vivo Immune-Modulatory Activity of Lefamulin in an Influenza Virus A (H1N1) Infection Model in Mice

Lefamulin is a first-in-class systemic pleuromutilin antimicrobial and potent inhibitor of bacterial translation, and the most recent novel antimicrobial approved for the treatment of community-acquired pneumonia (CAP). It exhibits potent antibacterial activity against the most prevalent bacterial pathogens that cause typical and atypical pneumonia and other infectious diseases. Early studies indicate additional anti-inflammatory activity. In this study, we further investigated the immune-modulatory activity of lefamulin in the influenza A/H1N1 acute respiratory distress syndrome (ARDS) model in BALB/c mice. Comparators included azithromycin, an anti-inflammatory antimicrobial, and the antiviral oseltamivir. Lefamulin significantly decreased the total immune cell infiltration, specifically the neutrophils, inflammatory monocytes, CD4+ and CD8+ T-cells, NK cells, and B-cells into the lung by Day 6 at both doses tested compared to the untreated vehicle control group (placebo), whereas azithromycin and oseltamivir did not significantly affect the total immune cell counts at the tested dosing regimens. Bronchioalveolar lavage fluid concentrations of pro-inflammatory cytokines and chemokines including TNF-α, IL-6, IL-12p70, IL-17A, IFN-γ, and GM-CSF were significantly reduced, and MCP-1 concentrations were lowered (not significantly) by lefamulin at the clinically relevant 'low' dose on Day 3 when the viral load peaked. Similar effects were also observed for oseltamivir and azithromycin. Lefamulin also decreased the viral load (TCID50) by half a log10 by Day 6 and showed positive effects on the gross lung pathology and survival. Oseltamivir and lefamulin were efficacious in the suppression of the development of influenza-induced bronchi-interstitial pneumonia, whereas azithromycin did not show reduced pathology at the tested treatment regimen. The observed anti-inflammatory and immune-modulatory activity of lefamulin at the tested treatment regimens highlights a promising secondary pharmacological property of lefamulin. While these results require confirmation in a clinical trial, they indicate that lefamulin may provide an immune-modulatory activity beyond its proven potent antibacterial activity. This additional activity may benefit CAP patients and potentially prevent acute lung injury (ALI) and ARDS.

Increased levels of GM-CSF and CXCL10 and low CD8+ memory stem T Cell count are markers of immunosenescence and severe COVID-19 in older people

BACKGROUND

Ageing leads to altered immune responses, resulting in higher susceptibility to certain infections in the elderly. Immune ageing is a heterogeneous process also associated with inflammaging, a low-grade chronic inflammation. Altered cytotoxic T cell responses and cytokine storm have previously been described in severe COVID-19 cases, however the parameters responsible for such immune response failures are not well known. The aim of our study was to characterize CD8+ T cells and cytokines associated with ageing, in a cohort of patients aged over 70 years stratified by COVID-19 severity.

RESULTS

One hundred and four patients were included in the study. We found that, in older people, COVID-19 severity was associated with (i) higher level of GM-CSF, CXCL10 (IP-10), VEGF, IL-1β, CCL2 (MCP-1) and the neutrophil to lymphocyte ratio (NLR), (ii) increased terminally differentiated CD8+T cells, and (ii) decreased early precursors CD8+ T stem cell-like memory cells (TSCM) and CD27+CD28+. The cytokines mentioned above were found at higher concentrations in the COVID-19+ older cohort compared to a younger cohort in which they were not associated with disease severity.

CONCLUSIONS

Our results highlight the particular importance of the myeloid lineage in COVID-19 severity among older people. As GM-CSF and CXCL10 were not associated with COVID-19 severity in younger patients, they may represent disease severity specific markers of ageing and should be considered in older people care.

Recognition of granulocyte-macrophage colony-stimulating factor by specific S100 proteins

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a pleiotropic myelopoietic growth factor and proinflammatory cytokine, clinically used for multiple indications and serving as a promising target for treatment of many disorders, including cancer, multiple sclerosis, rheumatoid arthritis, psoriasis, asthma, COVID-19. We have previously shown that dimeric Ca2+-bound forms of S100A6 and S100P proteins, members of the multifunctional S100 protein family, are specific to GM-CSF. To probe selectivity of these interactions, the affinity of recombinant human GM-CSF to dimeric Ca2+-loaded forms of 18 recombinant human S100 proteins was studied by surface plasmon resonance spectroscopy. Of them, only S100A4 protein specifically binds to GM-CSF with equilibrium dissociation constant, Kd, values of 0.3-2 μM, as confirmed by intrinsic fluorescence and chemical crosslinking data. Calcium removal prevents S100A4 binding to GM-CSF, whereas monomerization of S100A4/A6/P proteins disrupts S100A4/A6 interaction with GM-CSF and induces a slight decrease in S100P affinity for GM-CSF. Structural modelling indicates the presence in the GM-CSF molecule of a conserved S100A4/A6/P-binding site, consisting of the residues from its termini, helices I and III, some of which are involved in the interaction with GM-CSF receptors. The predicted involvement of the 'hinge' region and F89 residue of S100P in GM-CSF recognition was confirmed by mutagenesis. Examination of S100A4/A6/P ability to affect GM-CSF signaling showed that S100A4/A6 inhibit GM-CSF-induced suppression of viability of monocytic THP-1 cells. The ability of the S100 proteins to modulate GM-CSF activity is relevant to progression of various neoplasms and other diseases, according to bioinformatics analysis. The direct regulation of GM-CSF signaling by extracellular forms of the S100 proteins should be taken into account in the clinical use of GM-CSF and development of the therapeutic interventions targeting GM-CSF or its receptors.

Heterogeneity of immune cells and their communications unveiled by transcriptome profiling in acute inflammatory lung injury

Background

Acute Respiratory Distress Syndrome (ARDS) or its earlier stage Acute lung injury (ALI), is a worldwide health concern that jeopardizes human well-being. Currently, the treatment strategies to mitigate the incidence and mortality of ARDS are severely restricted. This limitation can be attributed, at least in part, to the substantial variations in immunity observed in individuals with this syndrome.

Methods

Bulk and single cell RNA sequencing from ALI mice and single cell RNA sequencing from ARDS patients were analyzed. We utilized the Seurat program package in R and cellmarker 2.0 to cluster and annotate the data. The differential, enrichment, protein interaction, and cell-cell communication analysis were conducted.

Results

The mice with ALI caused by pulmonary and extrapulmonary factors demonstrated differential expression including Clec4e, Retnlg, S100a9, Coro1a, and Lars2. We have determined that inflammatory factors have a greater significance in extrapulmonary ALI, while multiple pathways collaborate in the development of pulmonary ALI. Clustering analysis revealed significant heterogeneity in the relative abundance of immune cells in different ALI models. The autocrine action of neutrophils plays a crucial role in pulmonary ALI. Additionally, there was a significant increase in signaling intensity between B cells and M1 macrophages, NKT cells and M1 macrophages in extrapulmonary ALI. The CXCL, CSF3 and MIF, TGFβ signaling pathways play a vital role in pulmonary and extrapulmonary ALI, respectively. Moreover, the analysis of human single-cell revealed DCs signaling to monocytes and neutrophils in COVID-19-associated ARDS is stronger compared to sepsis-related ARDS. In sepsis-related ARDS, CD8+ T and Th cells exhibit more prominent signaling to B-cell nucleated DCs. Meanwhile, both MIF and CXCL signaling pathways are specific to sepsis-related ARDS.

Conclusion

This study has identified specific gene signatures and signaling pathways in animal models and human samples that facilitate the interaction between immune cells, which could be targeted therapeutically in ARDS patients of various etiologies.

DNA Damage-driven Inflammatory Cytokines: Reprogramming of Tumor Immune Microenvironment and Application of Oncotherapy

DNA damage occurs across tumorigenesis and tumor development. Tumor intrinsic DNA damage can not only increase the risk of mutations responsible for tumor generation but also initiate a cellular stress response to orchestrate the tumor immune microenvironment (TIME) and dominate tumor progression. Accumulating evidence documents that multiple signaling pathways, including cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) and ataxia telangiectasia-mutated protein/ataxia telangiectasia and Rad3-related protein (ATM/ATR), are activated downstream of DNA damage and they are associated with the secretion of diverse cytokines. These cytokines possess multifaced functions in the anti-tumor immune response. Thus, it is necessary to deeply interpret the complex TIME reshaped by damaged DNA and tumor-derived cytokines, critical for the development of effective tumor therapies. This manuscript comprehensively reviews the relationship between the DNA damage response and related cytokines in tumors and depicts the dual immunoregulatory roles of these cytokines. We also summarize clinical trials targeting signaling pathways and cytokines associated with DNA damage and provide future perspectives on emerging technologies.

Changes in chemokine and growth factor levels may be useful biomarkers for monitoring disease severity in COVID-19 patients; a pilot study

Aim

The aim of the present study was to assess differences in the serum levels of chemokines and growth factors (GFs) between COVID-19 patients and healthy controls. The diagnostic utility of the analyzed proteins for monitoring the severity of the SARS-CoV- 2 infection based on the patients' MEWS scores was also assessed.

Materials and methods

The serum levels of chemokines and growth factors were analyzed in hospitalized COVID-19 patients (50 women, 50 men) with the use of the Bio-Plex Pro™ Human Cytokine Screening Panel (Biorad) and the Bio-Plex Multiplex system.

Results

The study demonstrated that serum levels of MIP-1α, RANTES, Eotaxin, CTACK, GRO-α, IP-10, MIG, basic-FGF, HGF, SCGF-β, G-CSF, M-CSF, SCF, MIF, LIF, and TRAIL were significant higher in COVID-19 patients than in the control group. The concentrations of CTACK, GRO-α, IP-10, MIG, basic-FGF, HGF, PDGF- BB, GM-CSF, SCF, LIF, and TRAIL were higher in asymptomatic/mildly symptomatic COVID-19 patients (stage 1) and COVID-19 patients with pneumonia without respiratory failure (stage 2). The receiver operating characteristic (ROC) analysis revealed that IP-10, MIF, MIG, and basic-FGF differentiated patients with COVID-19 from healthy controls with the highest sensitivity and specificity, whereas GM-CSF, basic-FGF, and MIG differentiated asymptomatic/mildly symptomatic COVID-19 patients (stage 1) from COVID-19 patients with pneumonia without respiratory failure (stage 2) with the highest sensitivity and specificity.

Conclusions

MIG, basic-FGF, and GM-CSF can be useful biomarkers for monitoring disease severity in patients with COVID-19.

pan-MHC and cross-Species Prediction of T Cell Receptor-Antigen Binding

Profiling the binding of T cell receptors (TCRs) of T cells to antigenic peptides presented by MHC proteins is one of the most important unsolved problems in modern immunology. Experimental methods to probe TCR-antigen interactions are slow, labor-intensive, costly, and yield moderate throughput. To address this problem, we developed pMTnet-omni, an Artificial Intelligence (AI) system based on hybrid protein sequence and structure information, to predict the pairing of TCRs of αβ T cells with peptide-MHC complexes (pMHCs). pMTnet-omni is capable of handling peptides presented by both class I and II pMHCs, and capable of handling both human and mouse TCR-pMHC pairs, through information sharing enabled this hybrid design. pMTnet-omni achieves a high overall Area Under the Curve of Receiver Operator Characteristics (AUROC) of 0.888, which surpasses competing tools by a large margin. We showed that pMTnet-omni can distinguish binding affinity of TCRs with similar sequences. Across a range of datasets from various biological contexts, pMTnet-omni characterized the longitudinal evolution and spatial heterogeneity of TCR-pMHC interactions and their functional impact. We successfully developed a biomarker based on pMTnet-omni for predicting immune-related adverse events of immune checkpoint inhibitor (ICI) treatment in a cohort of 57 ICI-treated patients. pMTnet-omni represents a major advance towards developing a clinically usable AI system for TCR-pMHC pairing prediction that can aid the design and implementation of TCR-based immunotherapeutics.

Epigenetic perspectives associated with COVID-19 infection and related cytokine storm: an updated review

PURPOSE

The COVID-19 pandemic caused by the novel Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) has put the world in a medical crisis for the past three years; nearly 6.3 million lives have been diminished due to the virus outbreak. This review aims to update the recent findings on COVID-19 infections from an epigenetic scenario and develop future perspectives of epi-drugs to treat the disease.

METHODS

Original research articles and review studies related to COVID-19 were searched and analyzed from the Google Scholar/PubMed/Medline databases mainly between 2019 and 2022 to brief the recent work.

RESULTS

Numerous in-depth studies of the mechanisms used by SARS-CoV-2 have been going on to minimize the consequences of the viral outburst. Angiotensin-Converting Enzyme 2 receptors and Transmembrane serine protease 2 facilitate viral entry to the host cells. Upon internalization, it uses the host machinery to replicate viral copies and alter the downstream regulation of the normal cells, causing infection-related morbidities and mortalities. In addition, several epigenetic regulations such as DNA methylation, acetylation, histone modifications, microRNA, and other factors (age, sex, etc.) are responsible for the regulations of viral entry, its immune evasion, and cytokine responses also play a major modulatory role in COVID-19 severity, which has been discussed in detail in this review.

CONCLUSION

Findings of epigenetic regulation of viral pathogenicity open a new window for epi-drugs as a possible therapeutical approach against COVID-19.

Chronic alcohol use primes bronchial cells for altered inflammatory response and barrier dysfunction during SARS-CoV-2 infection

Alcohol use disorder (AUD) is a significant public health concern and people with AUD are more likely to develop severe acute respiratory distress syndrome (ARDS) in response to respiratory infections. To examine whether AUD was a risk factor for more severe outcome in response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, we examined early responses to infection using cultured differentiated bronchial epithelial cells derived from brushings obtained from people with AUD or without AUD. RNA-seq analysis of uninfected cells determined that AUD cells were enriched for expression of epidermal genes as compared with non-AUD cells. Bronchial epithelial cells from patients with AUD showed a significant decrease in barrier function 72 h postinfection, as determined by transepithelial electrical resistance. In contrast, barrier function of non-AUD cells was enhanced 72 h after SARS-CoV-2 infection. AUD cells showed claudin-7 that did not colocalize with zonula occludens-1 (ZO-1), indicative of disorganized tight junctions. However, both AUD and non-AUD cells showed decreased β-catenin expression following SARS-CoV-2 infection. To determine the impact of AUD on the inflammatory response to SARS-CoV-2 infection, cytokine secretion was measured by multiplex analysis. SARS-CoV-2-infected AUD bronchial cells had enhanced secretion of multiple proinflammatory cytokines including TNFα, IL-1β, and IFNγ as opposed to non-AUD cells. In contrast, secretion of the barrier-protective cytokines epidermal growth factor (EGF) and granulocyte macrophage-colony stimulating factor (GM-CSF) was enhanced for non-AUD bronchial cells. Taken together, these data support the hypothesis that AUD is a risk factor for COVID-19, where alcohol primes airway epithelial cells for increased inflammation and increased barrier dysfunction and increased inflammation in response to infection by SARS-CoV-2.NEW & NOTEWORTHY Alcohol use disorder (AUD) is a significant risk factor for severe acute respiratory distress syndrome. We found that AUD causes a phenotypic shift in gene expression in human bronchial epithelial cells, enhancing expression of epidermal genes. AUD cells infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) had higher levels of proinflammatory cytokine secretion and barrier dysfunction not present in infected non-AUD cells, consistent with increased early COVID-19 severity due to AUD.

Ethanol-exposed lung fibroblasts cause airway epithelial barrier dysfunction

BACKGROUND

Chronic alcohol ingestion predisposes to lung injury and disrepair during sepsis. Our previous studies outlined roles for transforming growth factor-beta 1 (TGFβ1) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in epithelial barrier homeostasis and how alcohol perturbs their expression and signaling. Here we hypothesize that ethanol-exposed lung fibroblasts (LF) are a source of dysregulated TGFβ1 and GM-CSF and thereby alter airway epithelial barrier function.

METHODS

Human or rat LF were cultured ± ethanol for 2 weeks and then co-cultured with human or rat airway epithelial cells (AEC) seeded on Transwell permeable supports. In selected groups, a TGFβ1 receptor type 1 (TGFβR1) inhibitor (SB431542) or a TGFβ1 neutralizing antibody was applied. Transepithelial electrical resistance (TER) was measured prior to co-culture and on day 5 of co-culture. AEC were then analyzed for the expression of selected tight junction and mesenchymal proteins, and transwell membranes were analyzed by immunofluorescence microscopy for ZO-1 expression and localization. TGFβ1 and GM-CSF levels in conditioned media from the co-cultures were quantified by ELISA.

RESULTS

AEC co-cultured with ethanol-exposed LF (ELF) showed a significant reduction in TER and corresponding decreases in ZO-1 expression, whereas collagen type 1A1 and α-smooth muscle actin protein expression were increased. In parallel, in conditioned media from the ELF + AEC co-cultures, activated TGFβ1 levels increased and GM-CSF levels decreased. Notably, all the effects of ELF on the AEC were prevented by blocking TGFβ1 activity.

CONCLUSIONS

Prior ethanol exposure to LF induces barrier dysfunction in naive AEC in a paracrine fashion through activation of TGFβ1 signaling and suppression of GM-CSF. These experimental findings provide a potential mechanism by which chronic alcohol ingestion impairs airway epithelial integrity and renders individuals susceptible to lung injury.

Myeloid-derived suppressor cells exacerbate poly(I:C)-induced lung inflammation in mice with renal injury and older mice

Viral pneumonia is a global health burden with a high mortality rate, especially in the elderly and in patients with underlying diseases. Recent studies have found that myeloid-derived suppressor cells (MDSCs) are abundant in these patient groups; however, their roles in the progression of viral pneumonia remain unclear. In this study, we observed a substantial increase in MDSCs in a mouse model of renal ischemia/reperfusion (I/R) injury and in older mice. When intranasal polyinosinic-polycytidylic acid (poly(I:C)) administration was used to mimic viral pneumonia, mice with renal I/R injury exhibited more severe lung inflammation than sham mice challenged with poly(I:C). In addition, MDSC depletion attenuated lung inflammation in mice with I/R injury. Similar results were obtained in older mice compared with those in young mice. Furthermore, adoptive transfer of in vitro-differentiated MDSCs exacerbated poly(I:C)-induced lung inflammation. Taken together, these experimental results suggest that the increased proportion of MDSCs in mice with renal I/R injury and in older mice exacerbates poly(I:C)-induced lung inflammation. These findings have important implications for the treatment and prevention of severe lung inflammation caused by viral pneumonia.

Emerging aspects of cytokine storm in COVID-19: The role of proinflammatory cytokines and therapeutic prospects

COVID-19 has claimed millions of lives during the last 3 years since initial cases were reported in Wuhan, China, in 2019. Patients with COVID-19 suffer from severe pneumonia, high fever, acute respiratory distress syndrome (ARDS), and multiple-organ dysfunction, which may also result in fatality in extreme cases. Cytokine storm (CS) is hyperactivation of the immune system, wherein the dysregulated production of proinflammatory cytokines could result in excessive immune cell infiltrations in the pulmonary tissues, resulting in tissue damage. The immune cell infiltration could also occur in other tissues and organs and result in multiple organs' dysfunction. The key cytokines implicated in the onset of disease severity include TNF-α, IFN-γ, IL-6, IL-1β, GM-CSF, and G-CSF. Controlling the CS is critical in treating COVID-19 disease. Therefore, different strategies are employed to mitigate the effects of CS. These include using monoclonal antibodies directed against soluble cytokines or the cytokine receptors, combination therapies, mesenchymal stem cell therapy, therapeutic plasma exchange, and some non-conventional treatment methods to improve patient immunity. The current review describes the role/s of critical cytokines in COVID-19-mediated CS and the respective treatment modalities.

Engineering Materials and Devices for the Prevention, Diagnosis, and Treatment of COVID-19 and Infectious Diseases

Following the global spread of COVID-19, scientists and engineers have adapted technologies and developed new tools to aid in the fight against COVID-19. This review discusses various approaches to engineering biomaterials, devices, and therapeutics, especially at micro and nano levels, for the prevention, diagnosis, and treatment of infectious diseases, such as COVID-19, serving as a resource for scientists to identify specific tools that can be applicable for infectious-disease-related research, technology development, and treatment. From the design and production of equipment critical to first responders and patients using three-dimensional (3D) printing technology to point-of-care devices for rapid diagnosis, these technologies and tools have been essential to address current global needs for the prevention and detection of diseases. Moreover, advancements in organ-on-a-chip platforms provide a valuable platform to not only study infections and disease development in humans but also allow for the screening of more effective therapeutics. In addition, vaccines, the repurposing of approved drugs, biomaterials, drug delivery, and cell therapy are promising approaches for the prevention and treatment of infectious diseases. Following a comprehensive review of all these topics, we discuss unsolved problems and future directions.

CCL17/TARC in autoimmunity and inflammation-not just a T-cell chemokine

Chemokine (C-C) ligand 17 (CCL17) was first identified as thymus- and activation-regulated chemokine when it was found to be constitutively expressed in the thymus and identified as a T-cell chemokine. This chemoattractant molecule has subsequently been found at elevated levels in a range of autoimmune and inflammatory diseases, as well as in cancer. CCL17 is a C-C chemokine receptor type 4 (CCR4) ligand, with chemokine (C-C) ligand 22 being the other major ligand and, as CCR4 is highly expressed on helper T cells, CCL17 can play a role in T-cell-driven diseases, usually considered to be via its chemotactic activity on T helper 2 cells; however, given that CCR4 is also expressed by other cell types and there is elevated expression of CCL17 in many diseases, a broader CCL17 biology is suggested. In this review, we summarize the biology of CCL17, its regulation and its potential contribution to the pathogenesis of various preclinical models. Reference is made, for example, to recent literature indicating a role for CCL17 in the control of pain as part of a granulocyte macrophage-colony-stimulating factor/CCL17 pathway in lymphocyte-independent models and thus not as a T-cell chemokine. The review also discusses the potential for CCL17 to be a biomarker and a therapeutic target in human disorders.

An Inhalable Hybrid Biomimetic Nanoplatform for Sequential Drug Release and Remodeling Lung Immune Homeostasis in Acute Lung Injury Treatment

Interactions of lung macrophages and recruited neutrophils with the lung microenvironment continuously aggravate the dysregulation of lung inflammation in the pathogenesis of acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). Either modulating macrophages or destroying neutrophil counts cannot guarantee a satisfactory outcome in ARDS treatment. Aimed at inhibiting the coordinated action of neutrophils and macrophages and modulating the hyper-inflammatory condition, an inhalable biomimetic sequential drug-releasing nanoplatform was developed for the combinatorial treatment of ALI. The nanoplatform (termed D-SEL) was made by conjugating DNase I, as outer cleavable arms, to a serum exosomal and liposomal hybrid nanocarrier (termed SEL) via a matrix metalloproteinase 9 (MMP-9)-cleavable peptide and then encapsulating methylprednisolone sodium succinate (MPS). In lipopolysaccharide (LPS) induced ALI in mice, the MPS/D-SEL moved through muco-obstructive airways and was retained in the alveoli for over 24 h postinhalation. DNase I was then released from the nanocarrier first after responding to MMP-9, resulting in inner SEL core exposure, which precisely delivered MPS into macrophages for promoting M2 macrophage polarization. Local and sustained DNase I release degraded dysregulated neutrophil extracellular traps (NETs) and suppressed neutrophil activation and the mucus plugging microenvironment, which in turn amplified M2 macrophage polarization efficiency. Such dual-stage drug release behavior facilitated down-regulation of pro-inflammatory cytokines in the lung but anti-inflammatory cytokine production through remodeling lung immune homeostasis, ultimately promoting lung tissue repair. This work presents a versatile hybrid biomimetic nanoplatform for the local pulmonary delivery of dual-drug therapeutics and displays potential in the treatment of acute inflammation.

Recent progress and prospects for anti-cytokine therapy in preclinical and clinical acute lung injury

Acute respiratory distress syndrome (ARDS) is a heterogeneous cause of respiratory failure that has a rapid onset, a high mortality rate, and for which there is no effective pharmacological treatment. Current evidence supports a critical role of excessive inflammation in ARDS, resulting in several cytokines, cytokine receptors, and proteins within their downstream signalling pathways being putative therapeutic targets. However, unsuccessful trials of anti-inflammatory drugs have thus far hindered progress in the field. In recent years, the prospects of precision medicine and therapeutic targeting of cytokines coevolving into effective treatments have gained notoriety. There is an optimistic and growing understanding of ARDS subphenotypes as well as advances in treatment strategies and clinical trial design. Furthermore, large trials of anti-cytokine drugs in patients with COVID-19 have provided an unprecedented amount of information that could pave the way for therapeutic breakthroughs. While current clinical and nonclinical ARDS research suggest relatively limited potential in monotherapy with anti-cytokine drugs, combination therapy has emerged as an appealing strategy and may provide new perspectives on finding safe and effective treatments. Accurate evaluation of these drugs, however, also relies on well-founded experimental research and the implementation of biomarker-guided stratification in future trials. In this review, we provide an overview of anti-cytokine therapy for acute lung injury and ARDS, highlighting the current preclinical and clinical evidence for targeting the main cytokines individually and the therapeutic prospects for combination therapy.

Immune mechanisms underlying COVID-19 pathology and post-acute sequelae of SARS-CoV-2 infection (PASC)

With a global tally of more than 500 million cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections to date, there are growing concerns about the post-acute sequelae of SARS-CoV-2 infection (PASC), also known as long COVID. Recent studies suggest that exaggerated immune responses are key determinants of the severity and outcomes of the initial SARS-CoV-2 infection as well as subsequent PASC. The complexity of the innate and adaptive immune responses in the acute and post-acute period requires in-depth mechanistic analyses to identify specific molecular signals as well as specific immune cell populations which promote PASC pathogenesis. In this review, we examine the current literature on mechanisms of immune dysregulation in severe COVID-19 and the limited emerging data on the immunopathology of PASC. While the acute and post-acute phases may share some parallel mechanisms of immunopathology, it is likely that PASC immunopathology is quite distinct and heterogeneous, thus requiring large-scale longitudinal analyses in patients with and without PASC after an acute SARS-CoV-2 infection. By outlining the knowledge gaps in the immunopathology of PASC, we hope to provide avenues for novel research directions that will ultimately lead to precision therapies which restore healthy immune function in PASC patients.

Innate and adaptive immunity to SARS-CoV-2 and predisposing factors

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus (SARS-CoV-2), has affected all countries worldwide. Although some symptoms are relatively mild, others are still associated with severe and even fatal clinical outcomes. Innate and adaptive immunity are important for the control of SARS-CoV-2 infections, whereas a comprehensive characterization of the innate and adaptive immune response to COVID-19 is still lacking and the mechanisms underlying immune pathogenesis and host predisposing factors are still a matter of scientific debate. Here, the specific functions and kinetics of innate and adaptive immunity involved in SARS-CoV-2 recognition and resultant pathogenesis are discussed, as well as their immune memory for vaccinations, viral-mediated immune evasion, and the current and future immunotherapeutic agents. We also highlight host factors that contribute to infection, which may deepen the understanding of viral pathogenesis and help identify targeted therapies that attenuate severe disease and infection.

Host-Based Treatments for Severe COVID-19

COVID-19 has been a global health problem since 2020. There are different spectrums of manifestation of this disease, ranging from asymptomatic to extremely severe forms requiring admission to intensive care units and life-support therapies, mainly due to severe pneumonia. The progressive understanding of this disease has allowed researchers and clinicians to implement different therapeutic alternatives, depending on both the severity of clinical involvement and the causative molecular mechanism that has been progressively explored. In this review, we analysed the main therapeutic options available to date based on modulating the host inflammatory response to SARS-CoV-2 infection in patients with severe and critical illness. Although current guidelines are moving toward a personalised treatment approach titrated on the timing of presentation, disease severity, and laboratory parameters, future research is needed to identify additional biomarkers that can anticipate the disease course and guide targeted interventions on an individual basis.

Shaping of the alveolar landscape by respiratory infections and long-term consequences for lung immunity

Respiratory infections and especially viral infections, along with other extrinsic environmental factors, have been shown to profoundly affect macrophage populations in the lung. In particular, alveolar macrophages (AMs) are important sentinels during respiratory infections and their disappearance opens a niche for recruited monocytes (MOs) to differentiate into resident macrophages. Although this topic is still the focus of intense debate, the phenotype and function of AMs that recolonize the niche after an inflammatory insult, such as an infection, appear to be dictated in part by their origin, but also by local and/or systemic changes that may be imprinted at the epigenetic level. Phenotypic alterations following respiratory infections have the potential to shape lung immunity for the long-term, leading to beneficial responses such as protection against allergic airway inflammation or against other infections, but also to detrimental responses when associated with the development of immunopathologies. This review reports the persistence of virus-induced functional alterations in lung macrophages, and discusses the importance of this imprinting in explaining inter-individual and lifetime immune variation.

Role of GM-CSF in lung balance and disease

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a hematopoietic growth factor originally identified as a stimulus that induces the differentiation of bone marrow progenitor cells into granulocytes and macrophages. GM-CSF is now considered to be a multi-origin and pleiotropic cytokine. GM-CSF receptor signals activate JAK2 and induce nuclear signals through the JAK-STAT, MAPK, PI3K, and other pathways. In addition to promoting the metabolism of pulmonary surfactant and the maturation and differentiation of alveolar macrophages, GM-CSF plays a key role in interstitial lung disease, allergic lung disease, alcoholic lung disease, and pulmonary bacterial, fungal, and viral infections. This article reviews the latest knowledge on the relationship between GM-CSF and lung balance and lung disease, and indicates that there is much more to GM-CSF than its name suggests.

CD4+ T cells produce GM-CSF and drive immune-mediated glomerular disease by licensing monocyte-derived cells to produce MMP12

GM-CSF in glomerulonephritisDespite glomerulonephritis being an immune-mediated disease, the contributions of individual immune cell types are not clear. To address this gap in knowledge, Paust et al. characterized pathological immune cells in samples from patients with glomerulonephritis and in samples from mice with the disease. The authors found that CD4+ T cells producing granulocyte-macrophage colony-stimulating factor (GM-CSF) licensed monocytes to promote disease by producing matrix metalloproteinase 12 and disrupting the glomerular basement membrane. Targeting GM-CSF to inhibit this axis reduced disease severity in mice, implicating this cytokine as a potential therapeutic target for patients with glomerulonephritis. -CM.

Dampening type 2 properties of group 2 innate lymphoid cells by a gammaherpesvirus infection reprograms alveolar macrophages

Immunological dysregulation in asthma is associated with changes in exposure to microorganisms early in life. Gammaherpesviruses (γHVs), such as Epstein-Barr virus, are widespread human viruses that establish lifelong infection and profoundly shape host immunity. Using murid herpesvirus 4 (MuHV-4), a mouse γHV, we show that after infection, lung-resident and recruited group 2 innate lymphoid cells (ILC2s) exhibit a reduced ability to expand and produce type 2 cytokines in response to house dust mites, thereby contributing to protection against asthma. In contrast, MuHV-4 infection triggers GM-CSF production by those lung ILC2s, which orders the differentiation of monocytes (Mos) into alveolar macrophages (AMs) without promoting their type 2 functions. In the context of γHV infection, ILC2s are therefore essential cells within the pulmonary niche that imprint the tissue-specific identity of Mo-derived AMs and shape their function well beyond the initial acute infection.

An overview on the treatments and prevention against COVID-19

BACKGROUND

The coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to plague the world. While COVID-19 is asymptomatic in most individuals, it can cause symptoms like pneumonia, ARDS (acute respiratory distress syndrome), and death in others. Although humans are currently being vaccinated with several COVID-19 candidate vaccines in many countries, however, the world still is relying on hygiene measures, social distancing, and approved drugs.

RESULT

There are many potential therapeutic agents to pharmacologically fight COVID-19: antiviral molecules, recombinant soluble angiotensin-converting enzyme 2 (ACE2), monoclonal antibodies, vaccines, corticosteroids, interferon therapies, and herbal agents. By an understanding of the SARS-CoV-2 structure and its infection mechanisms, several vaccine candidates are under development and some are currently in various phases of clinical trials.

CONCLUSION

This review describes potential therapeutic agents, including antiviral agents, biologic agents, anti-inflammatory agents, and herbal agents in the treatment of COVID-19 patients. In addition to reviewing the vaccine candidates that entered phases 4, 3, and 2/3 clinical trials, this review also discusses the various platforms that are used to develop the vaccine COVID-19.

GM-CSF targeting in COVID-19: an approach based on fragile foundations

Coronavirus disease 2019 (COVID-19) arises as a result of a pathological inflammatory response following infection with the coronavirus SARS-CoV-2. Although the majority of people infected with this virus will experience minimal or mild symptoms, a proportion will go on to develop more severe disease requiring hospitalisation and oxygen therapy. The most severe forms produce acute respiratory failure, necessitating mechanical ventilation or extracorporeal membrane oxygenation (ECMO). The advent of SARS-CoV-2 vaccination has substantially altered the risk profile of COVID-19, with marked reductions in the severity of illness and hospitalisation. However, for unvaccinated patients and those who do not mount an effective immune response to vaccination, it remains a potentially lethal infection.

Trials of anti-GM-CSF therapies in COVID-19 show divergent results; this may be explained by underlying biology and the fragility of the study findings. Further investigation of the pathophysiology of COVID-19 is required to better target therapies.http://bit.ly/3O1AuIo

A randomised trial of anti-GM-CSF otilimab in severe COVID-19 pneumonia (OSCAR)

BACKGROUND

Granulocyte-macrophage colony-stimulating factor (GM-CSF) and dysregulated myeloid cell responses are implicated in the pathophysiology and severity of COVID-19.

METHODS

In this randomised, sequential, multicentre, placebo-controlled, double-blind study, adults aged 18-79 years (Part 1) or ≥70 years (Part 2) with severe COVID-19, respiratory failure and systemic inflammation (elevated C-reactive protein/ferritin) received a single intravenous infusion of otilimab 90 mg (human anti-GM-CSF monoclonal antibody) plus standard care (NCT04376684). The primary outcome was the proportion of patients alive and free of respiratory failure at Day 28.

RESULTS

In Part 1 (n=806 randomised 1:1 otilimab:placebo), 71% of otilimab-treated patients were alive and free of respiratory failure at Day 28 versus 67% who received placebo; the model-adjusted difference of 5.3% was not statistically significant (95% CI -0.8-11.4%, p=0.09). A nominally significant model-adjusted difference of 19.1% (95% CI 5.2-33.1%, p=0.009) was observed in the predefined 70-79 years subgroup, but this was not confirmed in Part 2 (n=350 randomised) where the model-adjusted difference was 0.9% (95% CI -9.3-11.2%, p=0.86). Compared with placebo, otilimab resulted in lower serum concentrations of key inflammatory markers, including the putative pharmacodynamic biomarker CC chemokine ligand 17, indicative of GM-CSF pathway blockade. Adverse events were comparable between groups and consistent with severe COVID-19.

CONCLUSIONS

There was no significant difference in the proportion of patients alive and free of respiratory failure at Day 28. However, despite the lack of clinical benefit, a reduction in inflammatory markers was observed with otilimab, in addition to an acceptable safety profile.

Translating the biology of β common receptor-engaging cytokines into clinical medicine

The family of cytokines that comprises IL-3, IL-5, and GM-CSF was discovered over 30 years ago, and their biological activities and resulting impact in clinical medicine has continued to expand ever since. Originally identified as bone marrow growth factors capable of acting on hemopoietic progenitor cells to induce their proliferation and differentiation into mature blood cells, these cytokines are also recognized as key mediators of inflammation and the pathobiology of diverse immunologic diseases. This increased understanding of the functional repertoire of IL-3, IL-5, and GM-CSF has led to an explosion of interest in modulating their functions for clinical management. Key to the successful clinical translation of this knowledge is the recognition that these cytokines act by engaging distinct dimeric receptors and that they share a common signaling subunit called β-common or βc. The structural determination of how IL-3, IL-5, and GM-CSF interact with their receptors and linking this to their differential biological functions on effector cells has unveiled new paradigms of cell signaling. This knowledge has paved the way for novel mAbs and other molecules as selective or pan inhibitors for use in different clinical settings.

Protein Release by Controlled Desorption from Transiently Cationic Nanoparticles

Therapeutic release from hydrogels is traditionally controlled by encapsulation within nanoparticles; however, this strategy is limited for the release of proteins due to poor efficiency and denaturation. To overcome this problem, we designed an encapsulation-free release platform where negatively charged proteins are adsorbed to the exterior of transiently cationic nanoparticles, thus allowing the nanoparticles to be formulated separately from the proteins. Release is then governed by the change in nanoparticle surface charge from positive to neutral. To achieve this, we synthesized eight zwitterionic poly(lactide-block-carboxybetaine) copolymer derivatives and formulated them into nanoparticles with differing surface chemistry. The nanoparticles were colloidally stable and lost positive charge at rates dependent on the hydrolytic stability of their surface ester groups. The nanoparticles (NPs) were dispersed in a physically cross-linked hyaluronan-based hydrogel with one of three negatively charged proteins (transferrin, panitumumab, or granulocyte-macrophage colony-stimulating factor) to assess their ability to control release. For all three proteins, dispersing NPs within the gels resulted in significant attenuation of release, with the extent modulated by the hydrolytic stability of the surface groups. Release was rapid from fast-hydrolyzing ester groups, reduced with slow-hydrolyzing bulky ester groups, and very slow with nonhydrolyzing amide groups. When positively charged lysozyme was loaded into the nanocomposite gel, there was no significant attenuation of release compared to gel alone. These data demonstrate that electrostatic interactions between the protein and NP are the primary driver of protein release from the hydrogel. All released proteins retained bioactivity as determined with in vitro cell assays. This release strategy shows tremendous versatility and provides a promising new platform for controlled release of anionic protein therapeutics.

Efficacy and safety of granulocyte-macrophage colony-stimulating factor (GM-CSF) antibodies in COVID-19 patients: a meta-analysis

OBJECTIVE

This study aims to determine the efficacy and safety of granulocyte-macrophage colony-stimulating factor (GM-CSF) antibodies in COVID-19 patients.

METHODS

We searched Cochrane Library, PubMed, Embase, and ClinicalTrials.gov databases until July 27, 2022. Both randomized control trials (RCTs) and cohort studies were included and analyzed separately. The outcomes included mortality, incidence of invasive mechanical ventilation (IMV), ventilation improvement rate (need oxygen therapy to without oxygen therapy), secondary infection, and adverse events (AEs). The odds ratio (OR) with a 95% confidence interval (CI) was calculated by a random-effects meta-analysis model.

RESULTS

Five RCTs and 2 cohort studies with 1726 COVID-19 patients were recruited (n = 866 in the GM-CSF antibody group and n = 891 in the control group). GM-CSF antibodies treatment reduced the incidence of IMV, which was supported by two cohort studies (OR 0.16; 95% CI 0.03, 0.74) and three RCTs (OR 0.62; 95% CI 0.41, 0.94). GM-CSF antibodies resulted in slight but not significant reductions in mortality (based on two cohort studies and five RCTs) and ventilation improvement (based on one cohort study and two RCTs). The sensitive analysis further showed the results of mortality and ventilation improvement rate became statistically significant when one included study was removed. Besides, GM-CSF antibodies did not increase the risks of the second infection (based on one cohort study and five RCTs) and AEs (based on five RCTs).

CONCLUSION

GM-CSF antibody treatments may be an efficacious and well-tolerant way for the treatment of COVID-19. Further clinical evidence is still warranted.

COVID-19 immunopathology: From acute diseases to chronic sequelae

The clinical manifestation of coronavirus disease 2019 (COVID-19) mainly targets the lung as a primary affected organ, which is also a critical site of immune cell activation by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, recent reports also suggest the involvement of extrapulmonary tissues in COVID-19 pathology. The interplay of both innate and adaptive immune responses is key to COVID-19 management. As a result, a robust innate immune response provides the first line of defense, concomitantly, adaptive immunity neutralizes the infection and builds memory for long-term protection. However, dysregulated immunity, both innate and adaptive, can skew towards immunopathology both in acute and chronic cases. Here we have summarized some of the recent findings that provide critical insight into the immunopathology caused by SARS-CoV-2, in acute and post-acute cases. Finally, we further discuss some of the immunomodulatory drugs in preclinical and clinical trials for dampening the immunopathology caused by COVID-19.

The presence of SARS-CoV-2 in multiple clinical specimens of a fatal case of COVID-19: a case report

BACKGROUND

The risk of developing severe and even fatal coronavirus disease 2019 (COVID-19) increases with various factors such as advanced age and chronic diseases, especially those treated with immunosuppressive drugs. Viral ribonucleic acid (RNA) and viral load detection in extra-pulmonary specimens have been proposed to indicate disease severity.

CASE PRESENTATION

Here we describe a fatal COVID-19 case of an 83-year-old Caucasian male patient with various underlying comorbidities, including cardiovascular and autoimmune disorders, as well as immunosuppression due to lymphoma treatment. Upon admission, the patient was radiologically diagnosed with severe COVID-19. The patient was febrile and presented with diarrhea, continued dyspnea, tachypnea, and low blood oxygen saturation, treated with high-concentration oxygen supplementation and antibacterial therapy. Overall the patient was treated for COVID-19 for 19 days. Blood tests were performed upon admission, on the fifth, 10th, 13th, and 19th day. In addition, nasopharyngeal swab, blood, urine, and fecal samples were collected from the patient on the 14th day for virological and immunological investigations. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was detectable in all samples collected from this patient, including blood plasma and peripheral blood mononuclear cells (PBMC), with very high viral loads. However, neither virus-specific IgA, IgM, nor IgG antibodies were detectable.

CONCLUSIONS

The various cardiovascular, autoimmune, and oncological disorders, advanced age, and the high levels of inflammatory markers predisposed the patient to severe COVID-19 and determined the fatal outcome of the disease. We believe that the multiple specimen SARS-CoV-2 positivity and extremely high viral loads in nasopharyngeal swab and fecal samples to be the result of COVID-19 severity, the inability of viral clearance and weakened immune response due to advanced age, comorbidities, and the presence of non-Hodgkin's lymphoma and the immunosuppressive treatment for it, highlighting the risks of COVID-19 in such patients.

Loss of GM-CSF-dependent instruction of alveolar macrophages in COVID-19 provides a rationale for inhaled GM-CSF treatment

GM-CSF promotes myelopoiesis and inflammation, and GM-CSF blockade is being evaluated as a treatment for COVID-19-associated hyperinflammation. Alveolar GM-CSF is, however, required for monocytes to differentiate into alveolar macrophages (AMs) that control alveolar homeostasis. By mapping cross-species AM development to clinical lung samples, we discovered that COVID-19 is marked by defective GM-CSF-dependent AM instruction and accumulation of pro-inflammatory macrophages. In a multi-center, open-label RCT in 81 non-ventilated COVID-19 patients with respiratory failure, we found that inhalation of rhu-GM-CSF did not improve mean oxygenation parameters compared with standard treatment. However, more patients on GM-CSF had a clinical response, and GM-CSF inhalation induced higher numbers of virus-specific CD8 effector lymphocytes and class-switched B cells, without exacerbating systemic hyperinflammation. This translational proof-of-concept study provides a rationale for further testing of inhaled GM-CSF as a non-invasive treatment to improve alveolar gas exchange and simultaneously boost antiviral immunity in COVID-19. This study is registered at ClinicalTrials.gov (NCT04326920) and EudraCT (2020-001254-22).

Pharmacological therapies and drug development targeting SARS-CoV-2 infection

The development of therapies for SARS-CoV-2 infection, based on virus biology and pathology, and of large- and small-scale randomized controlled trials, have brought forward several antiviral and immunomodulatory drugs targeting the disease severity. Casirivimab/Imdevimab monoclonal antibodies and convalescent plasma to prevent virus entry, Remdesivir, Molnupiravir, and Paxlovid nucleotide analogs to prevent viral replication, a variety of repurposed JAK-STAT signaling pathway inhibitors, corticosteroids, and recombinant agonists/antagonists of cytokine and interferons have been found to provide clinical benefits in terms of mortality and hospitalization. However, current treatment options face multiple clinical needs, and therefore, in this review, we provide an update on the challenges of the existing therapeutics and highlight drug development strategies for COVID-19 therapy, based on ongoing clinical trials, meta-analyses, and clinical case reports.

Coronavirus disease 2019 subphenotypes and differential treatment response to convalescent plasma in critically ill adults: secondary analyses of a randomized clinical trial

PURPOSE

Benefit from convalescent plasma therapy for coronavirus disease 2019 (COVID-19) has been inconsistent in randomized clinical trials (RCTs) involving critically ill patients. As COVID-19 patients are immunologically heterogeneous, we hypothesized that immunologically similar COVID-19 subphenotypes may differ in their treatment responses to convalescent plasma and explain inconsistent findings between RCTs .

METHODS

We tested this hypothesis in a substudy involving 1239 patients, by measuring 26 biomarkers (cytokines, chemokines, endothelial biomarkers) within the randomized, embedded, multifactorial, adaptive platform trial for community-acquired pneumonia (REMAP-CAP) that assigned 2097 critically ill COVID-19 patients to either high-titer convalescent plasma or usual care. Primary outcome was organ support free days at 21 days (OSFD-21) .

RESULTS

Unsupervised analyses identified three subphenotypes/endotypes. In contrast to the more homogeneous subphenotype-2 (N = 128 patients, 10.3%; with elevated type i and type ii effector immune responses) and subphenotype-3 (N = 241, 19.5%; with exaggerated inflammation), the subphenotype-1 had variable biomarker patterns (N = 870 patients, 70.2%). Subphenotypes-2, and -3 had worse outcomes, and subphenotype-1 had better outcomes with convalescent plasma therapy compared with usual care (median (IQR). OSFD-21 in convalescent plasma vs usual care was 0 (- 1, 21) vs 10 (- 1, to 21) in subphenotype-2; 1.5 (- 1, 21) vs 12 (- 1, to 21) in suphenotype-3, and 0 (- 1, 21) vs 0 (- 1, to 21) in subphenotype-1 (test for between-subphenotype differences in treatment effects p = 0.008).

CONCLUSIONS

We reported three COVID-19 subphenotypes, among critically ill adults, with differential treatment effects to ABO-compatible convalescent plasma therapy. Differences in subphenotype prevalence between RCT populations probably explain inconsistent results with COVID-19 immunotherapies.

Evaluation of porcine GM-CSF during PRRSV infection in vitro and in vivo indicating a protective role of GM-CSF related with M1 biased activation in alveolar macrophage during PRRSV infection

Granulocyte-macrophage colony stimulating factor (GM-CSF), participates in diverse biological processes associated with innate and adaptive immunity, has unknown effects during PRRSV infection. Here, a double-antibody sandwich ELISA for pGM-CSF was developed in-house for evaluation of pGM-CSF level during PRRSV infection both in vitro and in vivo. In in vitro assay, it was notable that PRRSV-infected porcine alveolar macrophages (PAMs) yielded inconsistent pGM-CSF protein- and mRNA-level, suggesting a post-transcriptional inhibition of pGM-CSF mRNA was employed by PRRSV. Meanwhile, concurrent analysis of pGM-CSF levels in serum samples from PRRSV-infected piglets suggested that effect of PRRSV infection demonstrated minimum effect on pGM-CSF levels regardless of PRRSV virulence phenotypes. Moreover, in vitro treatment of PAMs with pGM-CSF prior PRRSV inoculation did not inhibit PRRSV replication in PAMs although genes downstream of pGM-CSF in PAMs could be upregulated by pGM-CSF treatment. Meanwhile, knockdown of pGM-CSF using siRNA did not enhance PRRSV replication as well. Intriguingly, therapeutic antibody treatment of HP-PRRSV-infected piglets led to significantly increased serum pGM-CSF levels, thus aligning with low pneumonia incidence and low intracellular PRRSV-RNA levels in PAMs of therapeutic antibody treated piglets. Furthermore, transcriptome analysis of PAMs from infected piglets revealed increased serum pGM-CSF levels correlated with activation of downstream signal of pGM-CSF in PAMs as evidenced by a M1-like phenotypes of gene expression pattern, implying a potential host-protective role played by pGM-CSF for PRRSV infection in vivo. In conclusion, our results demonstrated developments of a highly sensitive and specific ELISA for pGM-CSF and revealed a potential protective role conferred by pGM-CSF during PRRSV infection.

GM-CSF+ Tc17 cells are required to bolster vaccine immunity against lethal fungal pneumonia without causing overt pathology

GM-CSF co-expressing T17 cells instigate pathologic inflammation during autoimmune disorders, but their function in immunity to infections is unclear. Here, we demonstrate the role of GM-CSF⁺Tc17 cells for vaccine immunity against lethal fungal pneumonia and the cytokine requirements for their induction and memory homeostasis. Vaccine-induced GM-CSF⁺ Tc17 cells are necessary to bolster pulmonary fungal immunity without inflating pathology. Although GM-CSF expressing Tc17 cells preferentially elevate during the memory phase, their phenotypic attributes strongly suggest they are more like Tc17 cells than IFNγ-producing Tc1 cells. IL-1 and IL-23, but not GM-CSF, are necessary to elicit GM-CSF⁺Tc17 cells following vaccination. IL-23 is dispensable for memory Tc17 and GM-CSF⁺ Tc17 cell maintenance, but recall responses of effector or memory Tc17 cells in the lung require it. Our study reveals the beneficial, nonpathological role of GM-CSF⁺ Tc17 cells during fungal vaccine immunity.

GM-CSF⁺ and IL-17A⁺ lineages of T cells are instrumental in controlling many fungal and bacterial infections and implicated in autoimmune pathology, host-microbial interactions at the mucosal surfaces, and neuro-immune nexus. Mudalagiriyappa et al. show that GM-CSF expressing Tc17 cells are necessary for mediating fungal vaccine immunity without augmenting pathology.

Nascent RHOH acts as a molecular brake on actomyosin-mediated effector functions of inflammatory neutrophils

In contrast to molecular changes associated with increased inflammatory responses, little is known about intracellular counter-regulatory mechanisms that control signaling cascades associated with functional responses of neutrophils. Active RHO GTPases are typically considered as effector proteins that elicit cellular responses. Strikingly, we show here that RHOH, although being constitutively GTP-bound, limits neutrophil degranulation and the formation of neutrophil extracellular traps (NETs). Mechanistically, RHOH is induced under inflammatory conditions and binds to non-muscle myosin heavy chain IIA (NMHC IIA) in activated neutrophils in order to inhibit the transport of mitochondria and granules along actin filaments, which is partially reverted upon disruption of the interaction with NMHC IIA by introducing a mutation in RhoH at lysine 34 (RhoHK34A). In parallel, RHOH inhibits actin polymerization presumably by modulating RAC1 activity. In vivo studies using Rhoh-/- mice, demonstrate an increased antibacterial defense capability against Escherichia coli (E. coli). Collectively, our data reveal a previously undefined role of RHOH as a molecular brake for actomyosin-mediated neutrophil effector functions, which represents an intracellular regulatory axis involved in controlling the strength of an antibacterial inflammatory response.

Inflammatory pathways in COVID-19: Mechanism and therapeutic interventions

The 2019 coronavirus disease (COVID-19) pandemic has become a global crisis. In the immunopathogenesis of COVID-19, SARS-CoV-2 infection induces an excessive inflammatory response in patients, causing an inflammatory cytokine storm in severe cases. Cytokine storm leads to acute respiratory distress syndrome, pulmonary and other multiorgan failure, which is an important cause of COVID-19 progression and even death. Among them, activation of inflammatory pathways is a major factor in generating cytokine storms and causing dysregulated immune responses, which is closely related to the severity of viral infection. Therefore, elucidation of the inflammatory signaling pathway of SARS-CoV-2 is important in providing otential therapeutic targets and treatment strategies against COVID-19. Here, we discuss the major inflammatory pathways in the pathogenesis of COVID-19, including induction, function, and downstream signaling, as well as existing and potential interventions targeting these cytokines or related signaling pathways. We believe that a comprehensive understanding of the regulatory pathways of COVID-19 immune dysregulation and inflammation will help develop better clinical therapy strategies to effectively control inflammatory diseases, such as COVID-19.

ELF5 is a potential respiratory epithelial cell-specific risk gene for severe COVID-19

Despite two years of intense global research activity, host genetic factors that predispose to a poorer prognosis of COVID-19 infection remain poorly understood. Here, we prioritise eight robust (e.g., ELF5) or suggestive but unreported (e.g., RAB2A) candidate protein mediators of COVID-19 outcomes by integrating results from the COVID-19 Host Genetics Initiative with population-based plasma proteomics using statistical colocalisation. The transcription factor ELF5 (ELF5) shows robust and directionally consistent associations across different outcome definitions, including a >4-fold higher risk (odds ratio: 4.88; 95%-CI: 2.47-9.63; p-value < 5.0 × 10-6) for severe COVID-19 per 1 s.d. higher genetically predicted plasma ELF5. We show that ELF5 is specifically expressed in epithelial cells of the respiratory system, such as secretory and alveolar type 2 cells, using single-cell RNA sequencing and immunohistochemistry. These cells are also likely targets of SARS-CoV-2 by colocalisation with key host factors, including ACE2 and TMPRSS2. In summary, large-scale human genetic studies together with gene expression at single-cell resolution highlight ELF5 as a risk gene for severe COVID-19, supporting a role of epithelial cells of the respiratory system in the adverse host response to SARS-CoV-2.

Recent advances in passive immunotherapies for COVID-19: The Evidence-Based approaches and clinical trials

In late 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged, causing a global pandemic called COVID-19. Currently, there is no definitive treatment for this emerging disease. Global efforts resulted in developing multiple platforms of COVID-19 vaccines, but their efficacy in humans should be wholly investigated in the long-term clinical and epidemiological follow-ups. Despite the international efforts, COVID-19 vaccination accompanies challenges, including financial and political obstacles, serious adverse effects (AEs), the impossibility of using vaccines in certain groups of people in the community, and viral evasion due to emerging novel variants of SARS-CoV-2 in many countries. For these reasons, passive immunotherapy has been considered a complementary remedy and a promising way to manage COVID-19. These approaches arebased on reduced inflammation due to inhibiting cytokine storm phenomena, immunomodulation,preventing acute respiratory distress syndrome (ARDS), viral neutralization, anddecreased viral load. This article highlights passive immunotherapy and immunomodulation approaches in managing and treating COVID-19 patients and discusses relevant clinical trials (CTs).

GM-CSF: A Double-Edged Sword in Cancer Immunotherapy

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a cytokine that drives the generation of myeloid cell subsets including neutrophils, monocytes, macrophages, and dendritic cells in response to stress, infections, and cancers. By modulating the functions of innate immune cells that serve as a bridge to activate adaptive immune responses, GM-CSF globally impacts host immune surveillance under pathologic conditions. As with other soluble mediators of immunity, too much or too little GM-CSF has been found to promote cancer aggressiveness. While too little GM-CSF prevents the appropriate production of innate immune cells and subsequent activation of adaptive anti-cancer immune responses, too much of GM-CSF can exhaust immune cells and promote cancer growth. The consequences of GM-CSF signaling in cancer progression are a function of the levels of GM-CSF, the cancer type, and the tumor microenvironment. In this review, we first discuss the secretion of GM-CSF, signaling downstream of the GM-CSF receptor, and GM-CSF’s role in modulating myeloid cell homeostasis. We then outline GM-CSF’s anti-tumorigenic and pro-tumorigenic effects both on the malignant cells and on the non-malignant immune and other cells in the tumor microenvironment. We provide examples of current clinical and preclinical strategies that harness GM-CSF’s anti-cancer potential while minimizing its deleterious effects. We describe the challenges in achieving the Goldilocks effect during administration of GM-CSF-based therapies to patients with cancer. Finally, we provide insights into how technologies that map the immune microenvironment spatially and temporally may be leveraged to intelligently harness GM-CSF for treatment of malignancies.