The Combination of IFN β and TNF Induces an Antiviral and Immunoregulatory Program via Non-Canonical Pathways Involving STAT2 and IRF9

Long COVID among people with HIV: A systematic review and meta-analysis

BACKGROUND

People with HIV might be at an increased risk of long COVID (LC) because of their immune dysfunction and chronic inflammation and alterations in immunological responses against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2; coronavirus disease 2019 [COVID-19]). This systematic review aimed to evaluate the association between HIV infection and LC and the prevalence and characteristics of and risk factors for LC among people with HIV.

METHODS

Multiple databases, including Embase, PubMed, PsycINFO, Web of Science, and Sociological Abstracts, were searched to identify articles published before June 2023. Published articles were included if they presented at least one LC outcome measure among people with HIV and used quantitative or mixed-methods study designs. For effects reported in three or more studies, meta-analyses using random-effects models were performed using R software.

RESULTS

We pooled 39 405 people with HIV and COVID-19 in 17 eligible studies out of 6158 publications in all the databases. It was estimated that 52% of people with HIV with SARS-CoV-2 infection developed at least one LC symptom. Results from the random-effects model showed that HIV infection was associated with an increased risk of LC (odds ratio 2.20; 95% confidence interval 1.25-3.86). The most common LC symptoms among people with HIV were cough, fatigue, and asthenia. Risk factors associated with LC among people with HIV included a history of moderate-severe COVID-19 illness, increased interferon-gamma-induced protein 10 or tumour necrosis factor-α, and decreased interferon-β, among others.

CONCLUSIONS

The COVID-19 pandemic continues to exacerbate health inequities among people with HIV because of their higher risk of developing LC. Our review is informative for public health and clinical communities to develop tailored strategies to prevent aggravated LC among people with HIV.

The dichotomic role of cytokines in aging

The chronic inflammation present in aged individuals is generally depicted as a detrimental player for longevity. Here, it is discussed several beneficial effects associated with the cytokines that are chronically elevated in inflammaging. These cytokines, such as IL-1β, type I interferons, IL-6 and TNF positively regulate macroautophagy, mitochondrial function, anti-tumor immune responses and skeletal muscle biogenesis, possibly contributing to longevity. On the other side, the detrimental and antagonistic role of these cytokines including the induction of sarcopenia, tissue damage and promotion of tumorigenesis are also discussed, underscoring the dichotomy associated with inflammaging and its players. In addition, it is discussed the role of the anti-inflammatory cytokine IL-10 and other cytokines that affect aging in a more linear way, such as IL-11, which promotes senescence, and IL-4 and IL-15, which promotes longevity. It is also discussed more specific regulators of aging that are downstream cytokines-mediated signaling.

Interference without interferon: interferon-independent induction of interferon-stimulated genes and its role in cellular innate immunity

Interferons (IFNs) are multifaceted proteins that play pivotal roles in orchestrating robust antiviral immune responses and modulating the intricate landscape of host immunity. The major signaling pathway activated by IFNs is the JAK/STAT (Janus kinase/signal transducer and activator of transcription) pathway, which leads to the transcription of a battery of genes, collectively known as IFN-stimulated genes (ISGs). While the well-established role of IFNs in coordinating the innate immune response against viral infections is widely acknowledged, recent years have provided a more distinct comprehension of the functional significance attributed to non-canonical, IFN-independent induction of ISGs. In this review, we summarize the non-conventional signaling pathways of ISG induction. These alternative pathways offer new avenues for developing antiviral strategies or immunomodulation in various diseases.

Dynamic control of gene expression by ISGF3 and IRF1 during IFNβ and IFNγ signaling

Type I interferons (IFN-I, including IFNβ) and IFNγ produce overlapping, yet clearly distinct immunological activities. Recent data show that the distinctness of global transcriptional responses to the two IFN types is not apparent when comparing their immediate effects. By analyzing nascent transcripts induced by IFN-I or IFNγ over a period of 48 h, we now show that the distinctiveness of the transcriptomes emerges over time and is based on differential employment of the ISGF3 complex as well as of the second-tier transcription factor IRF1. The distinct transcriptional properties of ISGF3 and IRF1 correspond with a largely diverse nuclear protein interactome. Mechanistically, we describe the specific input of ISGF3 and IRF1 into enhancer activation and the regulation of chromatin accessibility at interferon-stimulated genes (ISG). We further report differences between the IFN types in altering RNA polymerase II pausing at ISG 5' ends. Our data provide insight how transcriptional regulators create immunological identities of IFN-I and IFNγ.

Sustained induction of IP-10 by MRP8/14 via the IFNβ-IRF7 axis in macrophages exaggerates lung injury in endotoxemic mice

Background

As a damage-associated molecular pattern, the myeloid-related protein 8/14 (MRP8/14) heterodimer mediates various inflammatory diseases, such as sepsis. However, how MRP8/14 promotes lung injury by regulating the inflammatory response during endotoxemia remains largely unknown. This study aims at illuminating the pathological functions of MRP8/14 in endotoxemia.

Methods

An endotoxemic model was prepared with wild-type and myeloid cell-specific Mrp8 deletion (Mrp8ΔMC) mice for evaluating plasma cytokine levels. Lung injury was evaluated by hematoxylin and eosin (H&E) staining, injury scoring and wet-to-dry weight (W/D) ratio. The dynamic profile of interferon γ (IFNγ)-inducible protein 10 (IP-10) mRNA expression induced by macrophage MRP8/14 was determined by quantitative real-time polymerase chain reaction (qPCR). Immunoblotting was used to evaluate the increase in IP-10 level induced by activation of the JAK-STAT signaling pathway. Luciferase reporter assay was performed to detect the involvement of IRF7 in Ip-10 gene transcription. In vivo air pouch experiments were performed to determine the biological function of IP-10 induced by MRP8/14.

Results

Experiments with Mrp8ΔMC mice showed that MRP8/14 promoted the production of cytokines, including IP-10, in the bronchoalveolar lavage fluid (BALF) and lung injury in endotoxic mice. The result of qPCR showed sustained expression of Ip-10 mRNA in macrophages after treatment with MRP8/14 for 12 h. Neutralization experiments showed that the MRP8/14-induced Ip-10 expression in RAW264.7 cells was mediated by extracellular IFNβ. Western blotting with phosphorylation-specific antibodies showed that the JAK1/TYK2-STAT1 signaling pathway was activated in MRP8/14-treated RAW264.7 cells, leading to the upregulation of Ip-10 gene expression. IRF7 was further identified as a downstream regulator of the JAK-STAT pathway that mediated Ip-10 gene expression in macrophages treated with MRP8/14. In vivo air pouch experiments confirmed that the IFNβ-JAK1/TYK2-STAT1-IRF7 pathway was required for chemokine (C-X-C motif) receptor 3 (CXCR3)+ T lymphocyte migration, which promoted lung injury in the context of endotoxemia.

Conclusions

In summary, our study demonstrates that MRP8/14 induces sustained production of IP-10 via the IFNβ-JAK1/TYK2-STAT1-IRF7 pathway to attract CXCR3+ T lymphocytes into lung tissues and ultimately results in lung injury by an excessive inflammatory response in the context of endotoxemia.

HIV and inflammatory markers are associated with persistent COVID-19 symptoms

BACKGROUND

A proportion of COVID19 survivors may present with long-COVID, which is persistent symptoms lasting four or more weeks post SARS-CoV-2 infection. These symptoms may be mild to severe, and may affect different organ-systems of the body.

AIMS

The main objective of this study was to determine the demographic, clinical and immunological factors associated with long COVID.

MATERIALS & METHODS

We conducted a nested case control study, with a total of 94 study participants initially included, and 64 participants matched for age and sex for biomarker analyses.

RESULTS

32/94 (34.1%) of all the participants had long COVID. Respiratory symptoms were the most common (59.5%) followed by the musculoskeletal symptoms (28.1%). HIV was an independent predictor of long COVID (adjusted odds ratio = 2.7; p = .037). In all the 64 matched cases and controls, IFN-β was significantly higher among controls than cases. After stratifying by HIV, IL6 was significantly higher among cases than controls in the HIV- group (2.06 vs. 0.81 pg/mL; p = .02). On the other hand, IFN-β was significantly higher among controls than cases in the HIV+ group (251 vs. 0 pg/mL; p = .01).

CONCLUSION

HIV infection is a risk factor for long COVID, and inflammatory markers associated with long COVID may be slightly different for HIV- and HIV+ individuals.

Insights gained from single-cell analysis of immune cells in tofacitinib treatment of Vogt-Koyanagi-Harada disease

Vogt-Koyanagi-Harada disease (VKH) is an important refractory uveitis mediated by pathological T cells (TCs). Tofacitinib (TOFA) is a JAK- targeted therapy for several autoimmune diseases. However, the specific pathogenesis and targeted therapeutics for VKH remain largely unknown. Based on single-cell RNA sequencing and mass cytometry, we present what we believe is the first multimodal, high-dimensional analysis to generate a comprehensive human immune atlas regarding subset composition, gene signatures, enriched pathways, and intercellular interactions of VKH patients undergoing TOFA therapy. Patients with VKH are characterized by TCs' polarization from naive to effector and memory subsets, together with accrued monocytes and upregulated cytokines and JAK/STAT signaling pathways. In vitro, TOFA reversed Th17/Treg imbalance and inhibited IL-2-induced STAT1/3 phosphorylation. TOFA alleviated VKH symptoms by restoring pathological TCs' polarization and functional marker expression and downregulating cytokine signaling and lymphocyte function. Remarkably, inflammation-related responses and intercellular interactions decreased after TOFA treatment, particularly in monocytes. Notably, we identified 2 inflammation- and JAK-associated monocyte subpopulations that were strongly implicated in VKH pathogenesis and mechanisms involved in TOFA treatment. Here, we provide a potentially novel JAK-targeted therapy for VKH and elaborate on the possible therapeutic mechanisms of TOFA, expanding our knowledge of VKH pathological patterns.

Porcine Epidemic Diarrhea Virus nsp7 Inhibits Interferon-Induced JAK-STAT Signaling through Sequestering the Interaction between KPNA1 and STAT1

Porcine epidemic diarrhea virus (PEDV) is a highly pathogenic enteric coronavirus that causes high mortality in piglets. Interferon (IFN) responses are the primary defense mechanism against viral infection; however, viruses always evolve elaborate strategies to antagonize the antiviral action of IFN. Previous study showed that PEDV nonstructural protein 7 (nsp7), a component of the viral replicase polyprotein, can antagonize ploy(I:C)-induced type I IFN production. Here, we found that PEDV nsp7 also antagonized IFN-α-induced JAK-STAT signaling and the production of IFN-stimulated genes. PEDV nsp7 did not affect the protein and phosphorylation levels of JAK1, Tyk2, STAT1, and STAT2 or the formation of the interferon-stimulated gene factor 3 (ISGF3) complex. However, PEDV nsp7 prevented the nuclear translocation of STAT1 and STAT2. Mechanistically, PEDV nsp7 interacted with the DNA binding domain of STAT1/STAT2, which sequestered the interaction between karyopherin α1 (KPNA1) and STAT1, thereby blocking the nuclear transport of ISGF3. Collectively, these data reveal a new mechanism developed by PEDV to inhibit type I IFN signaling pathway. IMPORTANCE In recent years, an emerging porcine epidemic diarrhea virus (PEDV) variant has gained attention because of serious outbreaks of piglet diarrhea in China and the United States. Coronavirus nonstructural protein 7 (nsp7) has been proposed to act with nsp8 as part of an RNA primase to generate RNA primers for viral RNA synthesis. However, accumulating evidence indicates that coronavirus nsp7 can also antagonize type I IFN production. Our present study extends previous findings and demonstrates that PEDV nsp7 also antagonizes IFN-α-induced IFN signaling by competing with KPNA1 for binding to STAT1, thereby enriching the immune regulation function of coronavirus nsp7.

The Activated Macrophage - A Tough Fortress for Virus Invasion: How Viruses Strike Back

Macrophages (Mφ) are innate immune cells with a variety of functional phenotypes depending on the cytokine microenvironment they reside in. Mφ exhibit distinct activation patterns that are found within a wide array of activation states ranging from the originally discovered classical pro-inflammatory (M1) to the anti-inflammatory (M2) with their multi-facades. M1 cells are induced by IFNγ + LPS, while M2 are further subdivided into M2a (IL-4), M2b (Immune Complex) and M2c (IL-10) based on their inducing stimuli. Not surprisingly, Mφ activation influences the outcome of viral infections as they produce cytokines that in turn activate cells of the adaptive immune system. Generally, activated M1 cells tend to restrict viral replication, however, influenza and HIV exploit inflammation to support their replication. Moreover, M2a polarization inhibits HIV replication at the post-integration level, while HCMV encoded hrIL-10 suppresses inflammatory reactions by facilitating M2c formation. Additionally, viruses such as LCMV and Lassa Virus directly suppress Mφ activation leading to viral chronicity. Here we review how Mφ activation affects viral infection and the strategies by which viruses manipulate Mφ polarization to benefit their own fitness. An understanding of these mechanisms is important for the development of novel immunotherapies that can sway Mφ phenotype to inhibit viral replication.

Morphological cell profiling of SARS-CoV-2 infection identifies drug repurposing candidates for COVID-19

Since its emergence in China in December 2019, SARS-CoV-2 has caused a global pandemic. Repurposing of FDA-approved drugs is a promising strategy for identifying rapidly deployable treatments for COVID-19. Herein, we developed a pipeline for quantitative, high-throughput, image-based screening of SARS-CoV-2 infection in human cells that led to the identification of several FDA-approved drugs and clinical candidates with in vitro antiviral activity.

The global spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and the associated disease COVID-19, requires therapeutic interventions that can be rapidly identified and translated to clinical care. Traditional drug discovery methods have a >90% failure rate and can take 10 to 15 y from target identification to clinical use. In contrast, drug repurposing can significantly accelerate translation. We developed a quantitative high-throughput screen to identify efficacious agents against SARS-CoV-2. From a library of 1,425 US Food and Drug Administration (FDA)-approved compounds and clinical candidates, we identified 17 hits that inhibited SARS-CoV-2 infection and analyzed their antiviral activity across multiple cell lines, including lymph node carcinoma of the prostate (LNCaP) cells and a physiologically relevant model of alveolar epithelial type 2 cells (iAEC2s). Additionally, we found that inhibitors of the Ras/Raf/MEK/ERK signaling pathway exacerbate SARS-CoV-2 infection in vitro. Notably, we discovered that lactoferrin, a glycoprotein found in secretory fluids including mammalian milk, inhibits SARS-CoV-2 infection in the nanomolar range in all cell models with multiple modes of action, including blockage of virus attachment to cellular heparan sulfate and enhancement of interferon responses. Given its safety profile, lactoferrin is a readily translatable therapeutic option for the management of COVID-19.

Granulocyte macrophage colony-stimulating factor has come of age: From a vaccine adjuvant to antiviral immunotherapy

GM-CSF acts as a pro-inflammatory cytokine and a key growth factor produced by several immune cells such as macrophages and activated T cells. In this review, we discuss recent studies that point to the crucial role of GM-CSF in the immune response against infections. Upon induction, GM-CSF activates four main signalling networks including the JAK/STAT, PI3K, MAPK, and NFκB pathways. Many of these transduction pathways such as JAK/STAT signal via proteins commonly activated with other antiviral signalling cascades, such as those induced by IFNs. GM-CSF also helps defend against respiratory infections by regulating alveolar macrophage differentiation and enhancing innate immunity in the lungs. Here, we also summarize the numerous clinical trials that have taken advantage of GM-CSF's mechanistic attributes in immunotherapy. Moreover, we discuss how GM-CSF is used as an adjuvant in vaccines and how its activity is interfered with to reduce inflammation such as in the case of COVID-19. This review brings forth the current knowledge on the antiviral actions of GM-CSF, the associated signalling cascades, and its application in immunotherapy.

Cell Biology of Viral Infections

Viruses exhibit an elegant simplicity, as they are so basic, but so frightening. Although only a few are life threatening, they have substantial implications for human health and the economy, as exemplified by the ongoing coronavirus pandemic. Viruses are rather small infectious agents found in all types of life forms, from animals and plants to prokaryotes and archaebacteria. They are obligate intracellular parasites, and as such, subvert many molecular and cellular processes of the host cell to ensure their own replication, amplification, and subsequent spread. This special issue addresses the cell biology of viral infections based on a collection of original research articles, communications, opinions, and reviews on various aspects of virus-host cell interactions. Together, these articles not only provide a glance into the latest research on the cell biology of viral infections, but also include novel technological developments.

STAT2 Limits Host Species Specificity of Human Metapneumovirus

The host tropism of viral infection is determined by a variety of factors, from cell surface receptors to innate immune signaling. Many viruses encode proteins that interfere with host innate immune recognition in order to promote infection. STAT2 is divergent between species and therefore has a role in species restriction of some viruses. To understand the role of STAT2 in human metapneumovirus (HMPV) infection of human and murine tissues, we first infected STAT2-/- mice and found that HMPV could be serially passaged in STAT2-/-, but not WT, mice. We then used in vitro methods to show that HMPV inhibits expression of both STAT1 and STAT2 in human and primate cells, but not in mouse cells. Transfection of the murine form of STAT2 into STAT2-deficient human cells conferred resistance to STAT2 inhibition. Finally, we sought to understand the in vivo role of STAT2 by infecting hSTAT2 knock-in mice with HMPV, and found that mice had increased weight loss, inhibition of type I interferon signaling, and a Th2-polarized cytokine profile compared to WT mice. These results indicate that STAT2 is a target of HMPV in human infection, while the murine version of STAT2 restricts tropism of HMPV for murine cells and tissue.

[High expression of STAT2 in ovarian cancer and its effect on metastasis of ovarian cancer cells]

OBJECTIVE

To investigate the expression of signal transduction and activator of transcription 2 (STAT2) in ovarian cancer and its correlation with the prognosis of ovarian cancer patients and explore the role of STAT2 inregulating metastasis of ovarian cancer cells.

METHODS

RT-qPCR was performed to detect the expression of STAT2 mRNA in 62 fresh frozen ovarian cancer tissues and 62 normal ovarian tissues; immunohistochemistry was used to detect STAT2 protein expressions in 95 paraffin-embedded ovarian cancer samples and 33 normal ovarian tissues. Kaplan-Meier method was used to analyze the correlation between the expression of STAT2 and the prognosis of the patients. We also examined the relationship between STAT2 and the patients' prognosis by analyzing the data in Kaplan-Meier Plotter database. Western blotting was performed to detect the expression of STAT2 in different ovarian cancer cell lines. In A2780 cells with the highest STAT2 expression, we examined the effects of STAT2 interference on cell migration and invasiveness using Transwell migration assay and on the expressions of the downstream molecule epidermal growth factor receptor (EGFR).

RESULTS

Ovarian cancer tissues expressed significantly higher levels of STAT2 mRNA than normal ovarian tissue. A high STAT2 mRNA expression was correlated with an advanced FIGO stage. Immunohistochemistry showed that 67.4% of the ovarian cancer samples, as compared with 28.3% of normal ovarian tissues, showed high STAT2 expressions. In ovarian cancer patients, a high expression of STAT2 protein was associated with ascites volume, distant metastasis and FIGO stage (P < 0.05). Survival analysis showed that ovarian cancer patients with a high expression of STAT2 protein had poor overall survival (P=0.021) and progression-free survival (P=0.018). STAT2 was overexpressed in all the ovarian cancer cell lines tested, and A2780 cell lines showed the highest expression. Interference of STAT2 significantly suppressed the migration and invasiveness (P < 0.01) and lowered the expression level of EGFR in A2780 cells.

CONCLUSIONS

STAT2 is overexpressed in ovarian cancer. A high expression of STAT2 is associated with a poor prognosis of ovarian cancer patients. STAT2 may promote the metastasis of ovarian cancer by enhancing the expression of EGFR.