Immune response dynamics in COVID-19 patients to SARS-CoV-2 and other human coronaviruses

BPR3P0128, a non-nucleoside RNA-dependent RNA polymerase inhibitor, inhibits SARS-CoV-2 variants of concern and exerts synergistic antiviral activity in combination with remdesivir

Viral RNA-dependent RNA polymerase (RdRp), a highly conserved molecule in RNA viruses, has recently emerged as a promising drug target for broad-acting inhibitors. Through a Vero E6-based anti-cytopathic effect assay, we found that BPR3P0128, which incorporates a quinoline core similar to hydroxychloroquine, outperformed the adenosine analog remdesivir in inhibiting RdRp activity (EC50 = 0.66 µM and 3 µM, respectively). BPR3P0128 demonstrated broad-spectrum activity against various severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern. When introduced after viral adsorption, BPR3P0128 significantly decreased SARS-CoV-2 replication; however, it did not affect the early entry stage, as evidenced by a time-of-drug-addition assay. This suggests that BPR3P0128's primary action takes place during viral replication. We also found that BPR3P0128 effectively reduced the expression of proinflammatory cytokines in human lung epithelial Calu-3 cells infected with SARS-CoV-2. Molecular docking analysis showed that BPR3P0128 targets the RdRp channel, inhibiting substrate entry, which implies it operates differently-but complementary-with remdesivir. Utilizing an optimized cell-based minigenome RdRp reporter assay, we confirmed that BPR3P0128 exhibited potent inhibitory activity. However, an enzyme-based RdRp assay employing purified recombinant nsp12/nsp7/nsp8 failed to corroborate this inhibitory activity. This suggests that BPR3P0128 may inhibit activity by targeting host-related RdRp-associated factors. Moreover, we discovered that a combination of BPR3P0128 and remdesivir had a synergistic effect-a result likely due to both drugs interacting with separate domains of the RdRp. This novel synergy between the two drugs reinforces the potential clinical value of the BPR3P0128-remdesivir combination in combating various SARS-CoV-2 variants of concern.

Dynamics of temporal immune responses in nonhuman primates and humans immunized with COVID-19 vaccines

We assessed the humoral immune responses to a COVID-19 vaccine in a well-controlled rhesus macaque model compared to humans immunized with two mRNA vaccines over several months post-second dose. The plasma IgG levels against seven coronaviruses (including SARS-CoV-2) and antibody subtypes (IgG 1-4 and IgM) against SARS-CoV-2 were evaluated using multiplex assays. The neutralization capacity of plasma antibodies against the original SAR-CoV-2 isolate and nine variants was evaluated in vaccinated humans and non-human primates. Immunization of macaques and humans with SARS-CoV-2 vaccines induced a robust neutralizing antibody response. In non-SIV-infected adult macaques immunized with an adenoviral vector expressing S-RBD (n = 7) or N protein (n = 3), elevated levels of IgG and neutralizing antibodies were detected 2 weeks post-second dose. Immune responses to the S-RBD vaccine in SIV-infected adult macaques (n = 2) were similar to the non-SIV-infected animals. Adult humans immunized with Pfizer (n = 35) or Moderna (n = 18) vaccines developed IgG and neutralizing antibodies at 4 weeks post-second dose. In both vaccine groups, IgG 1 was the predominant subtype, followed by IgG 3. The IgG levels, including total and IgG 1,2,3 elicited by the Moderna vaccine, were significantly higher than the corresponding levels elicited by the Pfizer vaccine at 4 weeks post-second dose. A significant correlation was observed between the plasma total IgG antibody levels and neutralization titers in both macaques and humans. Furthermore, broad-spectrum neutralization antibodies against several variants of SARS-CoV-2 were detected in the plasma of both macaques and humans after two vaccinations.

Lipid Mediators and Cytokines/Chemokines Display Differential Profiles in Severe versus Mild/Moderate COVID-19 Patients

Host immune responses play a key role in COVID-19 pathogenesis. The underlying phenomena are orchestrated by signaling molecules such as cytokines/chemokines and lipid mediators. These immune molecules, including anti-SARS-CoV-2 antibodies, interact with immune cells and regulate host responses, contributing to inflammation that drives the disease. We investigated 48 plasma cytokines/chemokines, 21 lipid mediators, and anti-S protein (RBD) antibodies in COVID-19 patients (n = 56) and non-COVID-19 respiratory disease controls (n = 49), to identify immune-biomarker profiles. Cytokines/chemokines (IL-6, CXCL-10 (IP-10), HGF, MIG, MCP-1, and G-CSF) and lipid mediators (TxB2, 11-HETE, 9-HODE, 13-HODE, 5-HETE, 12-HETE, 15-HETE, 14S-HDHA, 17S-HDHA, and 5-oxo ETE) were significantly elevated in COVID-19 patients compared to controls. In patients exhibiting severe disease, pro-inflammatory cytokines/chemokines (IL-6, CXCL-10, and HGF) and anti-SARS-CoV-2 antibodies were significantly elevated. In contrast, lipid mediators involved in the reduction/resolution of inflammation, in particular, 5-HETE, 11-HETE, and 5-oxoETE, were significantly elevated in mild/moderate disease. Taken together, these immune-biomarker profiles provide insight into immune responses related to COVID-19 pathogenesis. Importantly, our findings suggest that elevation in plasma concentrations of IL-6, CXCL-10, HGF, and anti-SARS-CoV-2 antibodies can predict severe disease, whereas elevation in lipid mediators peaks early (compared to cytokines) and includes induction of mechanisms leading to reduction of inflammation, associated complications, and maintenance of homeostasis.

Electrochemical Immunosensors Based on Zinc Oxide Nanorods for Detection of Antibodies Against SARS-CoV-2 Spike Protein in Convalescent and Vaccinated Individuals

Even after over 2 years of the COVID-19 pandemic, research on rapid, inexpensive, and accurate tests remains essential for controlling and avoiding the global spread of SARS-CoV-2 across the planet during a potential reappearance in future global waves or regional outbreaks. Assessment of serological responses for COVID-19 can be beneficial for population-level surveillance purposes, supporting the development of novel vaccines and evaluating the efficacy of different immunization programs. This can be especially relevant for broadly used inactivated whole virus vaccines, such as CoronaVac, which produced lower titers of neutralizing antibodies. and showed lower efficacy for specific groups such as the elderly and immunocompromised. We developed an impedimetric biosensor based on the immobilization of SARS-CoV-2 recombinant trimeric spike protein (S protein) on zinc oxide nanorod (ZnONR)-modified fluorine-doped tin oxide substrates for COVID-19 serology testing. Due to electrostatic interactions, the negatively charged S protein was immobilized via physical adsorption. The electrochemical response of the immunosensor was measured at each modification step and characterized by scanning electron microscopy and electrochemical techniques. We successfully evaluated the applicability of the modified ZnONR electrodes using serum samples from COVID-19 convalescent individuals, CoronaVac-vaccinated with or without positive results for SARS-CoV-2 infection, and pre-pandemic samples from healthy volunteers as controls. ELISA for IgG anti-SARS-CoV-2 spike protein was performed for comparison, and ELISA for IgG anti-RBDs of seasonal coronavirus (HCoVs) was used to test the specificity of immunosensor detection. No cross-reactivity with HCoVs was detected using the ZnONR immunosensor, and more interestingly, the sensor presented higher sensitivity when compared to negative ELISA results. The results demonstrate that the ZnONRs/spike-modified electrode displayed sensitive results for convalescents and vaccinated samples and shows excellent potential as a tool for the population's assessment and monitoring of seroconversion and seroprevalence.

COVID-19 diagnostics: Molecular biology to nanomaterials

The SARS-CoV-2 pandemic has claimed around 6.4 million lives worldwide. The disease symptoms range from mild flu-like infection to life-threatening complications. The widespread infection demands rapid, simple, and accurate diagnosis. Currently used methods include molecular biology-based approaches that consist of conventional amplification by RT-PCR, isothermal amplification-based techniques such as RT-LAMP, and gene editing tools like CRISPR-Cas. Other methods include immunological detection including ELISA, lateral flow immunoassay, chemiluminescence, etc. Radiological-based approaches are also being used. Despite good analytical performance of these current methods, there is an unmet need for less costly and simpler tests that may be performed at point of care. Accordingly, nanomaterial-based testing has been extensively pursued. In this review, we discuss the currently used diagnostic techniques for SARS-CoV-2, their usefulness, and limitations. In addition, nanoparticle-based approaches have been highlighted as another potential means of detection. The review provides a deep insight into the current diagnostic methods and future trends to combat this deadly menace.

Ultrarapid and ultrasensitive detection of SARS-CoV-2 antibodies in COVID-19 patients via a 3D-printed nanomaterial-based biosensing platform

Rapid detection of antibodies during infection and after vaccination is critical for the control of infectious outbreaks, understanding immune response, and evaluating vaccine efficacy. In this manuscript, we evaluate a simple ultrarapid test for SARS-CoV-2 antibodies in COVID-19 patients, which gives quantitative results (i.e., antibody concentration) in 10-12 s using a previously reported nanomaterial-based three-dimensional (3D)-printed biosensing platform. This platform consists of a micropillar array electrode fabricated via 3D printing of aerosolized gold nanoparticles and coated with nanoflakes of graphene and specific SARS-CoV-2 antigens, including spike S1, S1 receptor-binding domain (RBD) and nucleocapsid (N). The sensor works on the principle of electrochemical transduction, where the change of sensor impedance is realized by the interactions between the viral proteins attached to the sensor electrode surface and the antibodies. The three sensors were used to test samples from 17 COVID-19 patients and 3 patients without COVID-19. Unlike other serological tests, the 3D sensors quantitatively detected antibodies at a concentration as low as picomole within 10-12 s in human plasma samples. We found that the studied COVID-19 patients had higher concentrations of antibodies to spike proteins (RBD and S1) than to the N protein. These results demonstrate the enormous potential of the rapid antibody test platform for understanding patients' immunity, disease epidemiology and vaccine efficacy, and facilitating the control and prevention of infectious epidemics.

A GABA-receptor agonist reduces pneumonitis severity, viral load, and death rate in SARS-CoV-2-infected mice

Gamma-aminobutyric acid (GABA) and GABA-receptors (GABA-Rs) form a major neurotransmitter system in the brain. GABA-Rs are also expressed by 1) cells of the innate and adaptive immune system and act to inhibit their inflammatory activities, and 2) lung epithelial cells and GABA-R agonists/potentiators have been observed to limit acute lung injuries. These biological properties suggest that GABA-R agonists may have potential for treating COVID-19. We previously reported that GABA-R agonist treatments protected mice from severe disease induced by infection with a lethal mouse coronavirus (MHV-1). Because MHV-1 targets different cellular receptors and is biologically distinct from SARS-CoV-2, we sought to test GABA therapy in K18-hACE2 mice which develop severe pneumonitis with high lethality following SARS-CoV-2 infection. We observed that GABA treatment initiated immediately after SARS-CoV-2 infection, or 2 days later near the peak of lung viral load, reduced pneumonitis severity and death rates in K18-hACE2 mice. GABA-treated mice had reduced lung viral loads and displayed shifts in their serum cytokine/chemokine levels that are associated with better outcomes in COVID-19 patients. Thus, GABA-R activation had multiple effects that are also desirable for the treatment of COVID-19. The protective effects of GABA against two very different beta coronaviruses (SARS-CoV-2 and MHV-1) suggest that it may provide a generalizable off-the-shelf therapy to help treat diseases induced by new SARS-CoV-2 variants and novel coronaviruses that evade immune responses and antiviral medications. GABA is inexpensive, safe for human use, and stable at room temperature, making it an attractive candidate for testing in clinical trials. We also discuss the potential of GABA-R agonists for limiting COVID-19-associated neuroinflammation.

Mesenchymal stem cell therapy on top of triple therapy with remdesivir, dexamethasone, and tocilizumab improves PaO2/FiO2 in severe COVID-19 pneumonia

Background

Despite patients with severe coronavirus disease (COVID-19) receiving standard triple therapy, including steroids, antiviral agents, and anticytokine therapy, health condition of certain patients continue to deteriorate. In Taiwan, the COVID-19 mortality has been high since the emergence of previous variants of this disease (such as alpha, beta, or delta). We aimed to evaluate whether adjunctive infusion of human umbilical cord mesenchymal stem cells (MSCs) (hUC-MSCs) on top of dexamethasone, remdesivir, and tocilizumab improves pulmonary oxygenation and suppresses inflammatory cytokines in patients with severe COVID-19.

Methods

Hospitalized patients with severe or critical COVID-19 pneumonia under standard triple therapy were separated into adjuvant hUC-MSC and non-hUC-MSC groups to compare the changes in the arterial partial pressure of oxygen (PaO₂)/fraction of inspired oxygen (FiO₂) ratio and biological variables.

Results

Four out of eight patients with severe or critical COVID-19 received either one (n = 2) or two (n = 2) doses of intravenous infusions of hUC-MSCs using a uniform cell dose of 1.0 × 10⁸. Both high-sensitivity C-reactive protein (hs-CRP) level and monocyte distribution width (MDW) were significantly reduced, with a reduction in the levels of interleukin (IL)-6, IL-13, IL-12p70 and vascular endothelial growth factor following hUC-MSC transplantation. The PaO₂/FiO₂ ratio increased from 83.68 (64.34–126.75) to 227.50 (185.25–237.50) and then 349.56 (293.03–367.92) within 7 days after hUC-MSC infusion (P < 0.001), while the change of PaO₂/FiO₂ ratio was insignificant in non-hUC-MSC patients (admission day: 165.00 [102.50–237.61]; day 3: 100.00 [72.00–232.68]; day 7: 250.00 [71.00–251.43], P = 0.923).

Conclusion

Transplantation of hUC-MSCs as adjunctive therapy improves pulmonary oxygenation in patients with severe or critical COVID-19. The beneficial effects of hUC-MSCs were presumably mediated by the mitigation of inflammatory cytokines, characterized by the reduction in both hs-CRP and MDW.

Two Years into the COVID-19 Pandemic: Lessons Learned

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly transmissible and virulent human-infecting coronavirus that emerged in late December 2019 in Wuhan, China, causing a respiratory disease called coronavirus disease 2019 (COVID-19), which has massively impacted global public health and caused widespread disruption to daily life. The crisis caused by COVID-19 has mobilized scientists and public health authorities across the world to rapidly improve our knowledge about this devastating disease, shedding light on its management and control, and spawned the development of new countermeasures. Here we provide an overview of the state of the art of knowledge gained in the last 2 years about the virus and COVID-19, including its origin and natural reservoir hosts, viral etiology, epidemiology, modes of transmission, clinical manifestations, pathophysiology, diagnosis, treatment, prevention, emerging variants, and vaccines, highlighting important differences from previously known highly pathogenic coronaviruses. We also discuss selected key discoveries from each topic and underline the gaps of knowledge for future investigations.

Protective Immunity of COVID-19 Vaccination with ChAdOx1 nCoV-19 Following Previous SARS-CoV-2 Infection: A Humoral and Cellular Investigation

Infections caused by SARS-CoV-2 induce a severe acute respiratory syndrome called COVID-19 and have led to more than six million deaths worldwide. Vaccination is the most effective preventative measure, and cellular and humoral immunity is crucial to developing individual protection. Here, we aim to investigate hybrid immunity against SARS-CoV-2 triggered by the ChAadOx1 nCoV-19 vaccine in a Brazilian cohort. We investigated the immune response from ChAadOx1 nCoV-19 vaccination in naïve (noCOVID-19) and previously infected individuals (COVID-19) by analyzing levels of D-dimers, total IgG, neutralizing antibodies (Nabs), IFN-γ (interferon-γ) secretion, and immunophenotyping of memory lymphocytes. No significant differences in D-dimer levels were observed 7 or 15 days after vaccination (DAV). All vaccinated individuals presented higher levels of total IgG or Nabs with a positive correlation (R = 0.88). Individuals in the COVID-19 group showed higher levels of antibody and memory B cells, with a faster antibody response starting at 7 DAV compared to noCOVID-19 at 15 DAV. Further, ChAadOx1 nCoV-19 vaccination led to enhanced IFN-γ production (15 DAV) and an increase in activated T CD4+ naïve cells in noCOVID-19 individuals in contrast with COVID-19 individuals. Hence, our data support that hybrid immunity triggered by ChAadOx1 nCoV-19 vaccination is associated with enhanced humoral response, together with a balanced cellular response.

What Is Currently Known about the Role of CXCL10 in SARS-CoV-2 Infection?

Dysregulation of the immune response plays an important role in the progression of SARS-CoV-2 infection. A "cytokine storm", which is a phenomenon associated with uncontrolled production of large amounts of cytokines, very often affects patients with COVID-19. Elevated activity of chemotactic cytokines, called chemokines, can lead to serious consequences. CXCL10 has an ability to activate its receptor CXCR3, predominantly expressed on macrophages, T lymphocytes, dendritic cells, natural killer cells, and B cells. So, it has been suggested that the chemokine CXCL10, through CXCR3, is associated with inflammatory diseases and may be involved in the development of COVID-19. Therefore, in this review paper, we focus on the role of CXCL10 overactivity in the pathogenesis of COVID-19. We performed an extensive literature search for our investigation using the MEDLINE/PubMed database. Increased concentrations of CXCL10 were observed in COVID-19. Elevated levels of CXCL10 were reported to be associated with a severe course and disease progression. Published studies revealed that CXCL10 may be a very good predictive biomarker of patient outcome in COVID-19, and that markedly elevated CXCL10 levels are connected with ARDS and neurological complications. It has been observed that an effective treatment for SARS-CoV-2 leads to inhibition of "cytokine storm", as well as reduction of CXCL10 concentrations. It seems that modulation of the CXCL10-CXCR3 axis may be an effective therapeutic target of COVID-19. This review describes the potential role of CXCL10 in the pathogenesis of COVID-19, as well as its potential immune-therapeutic significance. However, future studies should aim to confirm the prognostic, clinical, and therapeutic role of CXCL10 in SARS-CoV-2 infection.

T helper type (Th1/Th2) responses to SARS-CoV-2 and influenza A (H1N1) virus: From cytokines produced to immune responses

Cytokines produced by T helper cells (Th cells) have essential roles in the body's defense against viruses. Type 1 T helper (Th1) cells are essential for the host defense toward intracellular pathogens while T helper type 2 (Th2) cells are considered to be critical for the helminthic parasites' elimination swine-origin influenza A (H1N1) virus, a disease led to an epidemic in 2009 and rapidly spread globally via human-to-human transmission. Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused a global pandemic in 2020 and is a serious threat to the public health. Pulmonary immunopathology is the leading cause of death during influenza and SARS-CoV-2 epidemics and pandemics. Influenza and SARS-CoV-2 cause high levels of cytokines in the lung. Both inadequate levels and high levels of specific cytokines can have side effects. In this literature review article, we want to compare the Th1 and Th2 cells responses in SARS-CoV-2 and H1N1.

Evaluating the role of chemokines and chemokine receptors involved in coronavirus infection

INTRODUCTION

Coronaviruses are a large family of positive-stranded nonsegmented RNA viruses with genomes of 26-32 kilobases in length. Human coronaviruses are commonly associated with mild respiratory illness; however, the past three decades have seen the emergence of severe acute respiratory coronavirus (SARS-CoV), middle eastern respiratory coronavirus (MERS-CoV), and SARS-CoV-2 which is the etiologic agent for COVID-19. Severe forms of COVID-19 include acute respiratory distress syndrome (ARDS) associated with cytokine release syndrome that can culminate in multiorgan failure and death. Among the proinflammatory factors associated with severe COVID-19 are the chemokines CCL2, CCL3, CXCL8, and CXCL10. Infection of susceptible mice with murine coronaviruses, such as mouse hepatitis virus (MHV), elicits a similar chemokine response profile as observed in COVID-19 patients and these in vivo models have been informative and show that targeting chemokines reduces the severity of inflammation in target organs.

AREAS COVERED

PubMed was used using keywords: Chemokines and coronaviruses; Chemokines and mouse hepatitis virus; Chemokines and COVID-19. Clinicaltrials.gov was used using keywords: COVID-19 and chemokines; COVID-19 and cytokines; COVID-19 and neutrophil.

EXPERT OPINION

Chemokines and chemokine receptors are clinically relevant therapeutic targets for reducing coronavirus-induced inflammation.