Cholesterol 25-hydroxylase (CH25H) and its product 25-hydroxycholesterol (25HC) showed antiviral effects against various viruses in vitro. CH25H expression is regulated in mice by pro-inflammatory cytokine interferons (IFNs) in mice but data on its possible correlation with IFNs in humans are still unclear. We examined gene expression of CH25H, IFN-α, and IFN-β and serum levels of 25HC in Iranian patients with mild and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Fifty intensive care unit (ICU) patients and outpatients with SARS-CoV-2 and 25 healthy controls were studied. Gene expression of CH25H and relevant inflammatory cytokines was quantified in peripheral blood mononuclear cells by real-time polymerase chain reaction. The expression of CH25H and serum levels of 25HC were significantly higher in ICU patients with SARS-CoV-2. Notably, IFN-α levels increased in healthy controls. However, compared to healthy controls, IFN-β was considerably higher in outpatients. Finally, statistical analysis shows that no correlation was found between CH25H and IFN-α expression; nevertheless, a lower correlation was found with IFN-β. The data revealed that CH25H and 25HC levels increase after SARS-CoV-2 infection. In other words, decreased levels of those factors in severe patients compared with mild patients may indicate the importance of their function in controlling the progression of the disease.

Severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) infection is associated with proinflammatory cytokine release as mediators of host antiviral response to the infection. Cytokine persistent elevation leads to post-Coronavirus disease-2019 (COVID-19) post-COVID-19 sequela (PCS) reported in about 60% of patients affecting individual's normal life after recovery. This study evaluates relationship of cytokines and chemokines pattern during and postinfection to PCS events. Serum samples collected from 82 individuals with symptomatic, asymptomatic, or no SARS-CoV-2 infection were classified as recently or formerly infected groups according to levels of anti-2019nCoV Immunoglobulin G/Immunoglobulin M. Levels of interleukin (IL)-1α, IL-1β, IL-6, IL-8, interferon alpha (IFN-α), tumor necrosis factor alpha (TNF-α), granulocyte macrophage colony-stimulating factor (GM-CSF), and monocyte chemoattractant protein-1 were assessed via ELISA for each individual. All asymptomatic groups showed nonsignificant differences in cytokines' levels than control group. Significant elevation of IFN-α, TNF-α, and GM-CSF levels were observed in recent symptomatic, while IFN-α and TNF-α levels were significant in former symptomatic groups. We observed an association between fever with IL-1α and IFN-α levels, fatigue with TNF-α and GM-CSF, dyspnea with IFN-α, TNF-α, and GM-CSF, and chest-wheezing with GM-CSF. Individuals were surveyed 12 months postsampling for PCS events. Among 35 responders to survey, 8 (22.8%) reported PCS events, 6 of which were females. Upon studying PCS events, IL-8, IFN-α, TNF-α, and GM-CSF levels showed significant elevation in active infection, that was not seen in a resolved state of infection. Cytokines patterns suggest that either a persistent elevation in levels or damage caused during infection contributes to PCS. Although with the limited sample size, our study emphasizes the importance to conduct medical approaches targeting the associated cytokines to improve the PCS symptoms.

Despite knowledge gaps in understanding the full spectrum of the hyperinflammatory phase caused by SARS-CoV-2, according to the World Health Organization (WHO), COVID-19 is still the leading cause of death worldwide. Susceptible people to severe COVID-19 are those with underlying medical conditions or those with dysregulated and senescence-associated immune responses. As the immune system undergoes aging in the elderly, such drastic changes predispose them to various diseases and affect their responsiveness to infections, as seen in COVID-19. At-risk groups experience poor prognosis in terms of disease recovery. Changes in the quantity and quality of immune cell function have been described in numerous literature sites. Impaired immune cell function along with age-related metabolic changes can lead to features such as hyperinflammatory response, immunosenescence, and inflammaging in COVID-19. Inflammaging is related to the increased activity of the most inflammatory factors and is the main cause of age-related diseases and tissue failure in the elderly. Since hyperinflammation is a common feature of most severe cases of COVID-19, this pathway, which is not fully understood, leads to immunosenescence and inflammaging in some individuals, especially in the elderly and those with comorbidities. In this review, we shed some light on the age-related abnormalities of innate and adaptive immune cells and how hyperinflammatory immune responses contribute to the inflammaging process, leading to clinical deterioration. Further, we provide insights into immunomodulation-based therapeutic approaches, which are potentially important considerations in vaccine design for elderly populations.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine has been used worldwide on a large scale because of its potent ability to contain the coronavirus disease 2019 (COVID-19) pandemic, and the antibody response induced by the vaccine needs to be elucidated. Thus, we conducted a prospective trial in healthy subjects to observe the antibody response after three doses of inactivated vaccines. Our results showed that neutralizing antibody (NAb) levels were significantly higher after the booster vaccination compared to the second, a 4.9-fold increase, with the peak occurring at 28 days. The NAb level could be maintained for a longer period after the third vaccination, with higher levels still observed after 3 months. We did not observe significantly higher levels of SARS-CoV-2 spike-specific immunoglobulin G (S-IgG) and immunoglobulin M (IgM) after the third vaccination compared with the second vaccination; this was especially true for SARS-CoV-2 spike-specific immunoglobulin M (S-IgM), which was barely expressed. Notably, those who did not undergo NAb seroconversion after two doses of the vaccine produced high and long-lasting NAb after the third vaccination, confirming that they were not completely unresponsive to the vaccine. The NAb titer in younger subjects (aged 20-40 years) rose 3.4-fold compared with older subjects (aged 40-60 years) after the second vaccination, but the difference was narrowed after the third vaccination (2.8-fold increase). In addition, the levels of antibodies in older men were 3.4-fold lower than those in the older women after the third vaccination. Overall, this study elucidates the dynamic change in antibodies after three doses of vaccination, which provides a reference for the improvement of vaccination strategies.

The innate immune system recognizes conserved features of viral and microbial pathogens through pattern recognition receptors (PRRs). Toll-like receptors (TLRs) are one type of PRR used by the innate immune system to mediate the secretion of proinflammatory cytokines and promote innate and adaptive immune responses. TLR family members TLR7 and TLR8 (referred to as TLR7/8 from herein) are endosomal transmembrane receptors that recognize purine-rich single-stranded RNA (ssRNA) and bacterial DNA, eliciting an immunologic reaction to pathogens. TLR7/8 were discovered to mediate the secretion of proinflammatory cytokines by activating immune cells. In addition, accumulating evidence has indicated that TLR7/8 may be closely related to numerous immune-mediated disorders, specifically several types of cancer, autoimmune disease, and viral disease. TLR7/8 agonists and antagonists, which are used as drugs or adjuvants, have been identified in preclinical studies and clinical trials as promising immune stimulators for the immunotherapy of these immune-mediated disorders. These results provided reasoning to further explore immunotherapy for the treatment of immune-mediated disorders. Nevertheless, numerous needs remain unmet, and the therapeutic effects of TLR7/8 agonists and antagonists are poor and exert strong immune-related toxicities. The present review aimed to provide an overview of the TLR family members, particularly TLR7/8, and address the underlying molecular mechanisms and clinical implications of TLR7/8 in immune-mediated disorders. The aim of the work is to discuss the underlying molecular mechanisms and clinical implications of TLR7/8 in immune-mediated disorders.

Omicron variants have become the dominant SARS-CoV-2 variants due to their increased transmissibility and immune-escape ability. An outbreak of the Omicron variant BA.5.1.3 occurred in August 2022 in Sanya, China. Studying Omicron variants can promote the understanding of them and further contribute to managing the SARS-CoV-2 prevalence. This retrospective study analyzed the data of 258 patients with asymptomatic or mild SARS-CoV-2 admitted to the First Cabin Hospital of Sanya, China, between August 14 and September 4, 2022. The 258 patients comprised 128 males and 130 females with a mean age of 36.6 years and mean length of medical observation (LMO) of 10.1 days. Multiple linear regression analysis indicated that LMO was positively and negatively associated with age (p = 0.036) and vaccination status (p = 0.004), respectively. A Cox proportional-hazards model revealed that age (hazard ratio [HR] = 0.99, p = 0.029) and vaccination (HR = 1.23, p = 0.023) were risk and protective factors for LMO, respectively. Causal mediation analysis indicated that vaccination suppressed the effect of prolonging LMO caused by increasing age. Recovery times became longer with increasing age, which could be counterbalanced by vaccination. The present results indicate that vaccination interventions, even those developed through inactivated approaches, can still provide protection against Omicron variants.

Vitamin D exerts its antiviral effect through vitamin D receptor (VDR)/retinoid X receptor-mediated host immunomodulation. Besides the downregulation of VDR expression, its polymorphism was also observed among hepatitis B virus (HBV)-positive patients. To understand the possible link between VDR polymorphism and its altered expression during HBV infection and disease progression, VDR Apa-I [rs7975232 (C>A)] single nucleotide polymorphism (SNP) was analyzed in a case-control manner. VDR Apa-I (rs7975232, C>A) polymorphism was studied using 340 HBV patients and 102 healthy controls. Genotype analysis and gene expression study was performed using restriction fragment length polymorphism and quantitative polymerase chain reaction, respectively. Statistical analysis was performed using SPSS (IBM) considering p-value <0.05 as significant for comparing the differences between the groups. Significant mean difference in VDR expression was observed between HBV-positive patients (1.6 ± 0.94) and controls (0.69 ± 0.73). Furthermore, the mean fold change of Healthy control with CC genotype (1.92 ± 0.99) was found to be marginally significant compared with mutant genotype (CA/AA) (1.08 ± 0.43/0.59 ± 0.56, p = 0.045). In HBV+ patients, the mean fold change in the CC genotype was 0.88 ± 0.38, which exhibits a significant mean difference upon comparison with other genotypes (0.52 ± 0.49, 0.113 ± 0.34; p = 0.018, p = 0.048). However, the fold change value does not differ between CA and AA genotypes. Further comparative analysis of VDR expression between the control and case also exhibits significant differences (p = 0.001) among allelic variants. Observed genotype distribution frequency exhibits a significant association with disease type. The mutant genotype was found to be significantly associated with HBV infection and disease progression, (odds ratio = 0.730, 95% confidence interval = 0.462-1.152, p = 0.06). VDR SNP rs7975232 (C>A) may affect VDR expression by controlling several other variables and suggest that deviation from wild-type genotype (CC) is associated with downregulation of expression, which in turn involved in host immunomodulation in favor of HBV infection and disease progression.

Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) stimulates the plasma B cells to secrete specific antibodies against the viral antigen. However, not all antibodies can prevent the virus from entering the cells. The subpopulation of antibodies which blocks the entry of the virus into host cells is termed neutralizing antibodies (NAbs). The gold standard test for the detection of NAbs is the viral plaque reduction and neutralization test; however, various other methods can also be utilized to detect NAbs. In this study, we have developed an Enzyme Linked Immunosobent Assay (ELISA)-based protocol for rapid detection of SARS CoV-2 NAb by inhibiting the binding of the spike protein receptor-binding domain to angiotensin converting enzyme 2 and compared it with cPASS neutralizing antibody kit, which was approved by the Food and Drug Administration (FDA). The results obtained suggest that the in-house ELISA developed for the detection of NAbs against SARS-CoV-2 is rapid and reliable. Compared to FDA-approved GenScript's cPass assay, the specificity and the sensitivity of the in-house-developed ELISA kit were 100% (95% confidence intervals of 69.15-100.00) and 96% (95% confidence intervals of 86.29-99.51), respectively. Thus, the ELISA protocol developed to test the neutralizing activities of antibodies is rapid, which requires a BSL-2 infrastructure facility and can be easily performed. It has very high potential applications in the rapid screening of NAb against SARS-CoV-2.

The constant emergence of variants of concern (VOCs) challenges the effectiveness of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines over time. This is most concerning in clinically vulnerable groups, such as older adults. This study aimed to determine whether the novel adjuvant MF59-like adjuvant can improve cross-immunity against VOCs in aged animals. We compared the humoral and cellular immune responses of Alum and MF59-like adjuvant-formulated inactivated coronavirus disease 2019 (COVID-19) vaccines against prototype and SARS-CoV-2 variants in 18-month-old mice. Our results showed that two doses of the MF59-like adjuvant inactivated vaccines induced more robust binding and pseudo-neutralizing antibodies (Nabs) against the SARS-CoV-2 prototype and VOCs compared to the Alum-adjuvant and reduced Omicron variant escapes from Nabs in aged mice. The humoral immune responses of inactivated vaccines were much lower against VOCs than the prototype with or without adjuvants; however, T cell responses against VOCs were not affected. In addition, Alum and MF59-like adjuvanted vaccines induced Th1-biased immune responses with increased interferon-gamma and interleukin (IL)-2 secreting cells, and hardly detectable IL-4 and IL-5. Furthermore, the MF59-like adjuvant vaccine produced 1.9-2.0 times higher cross-reactive T cell responses against the SARS-CoV-2 prototype and VOCs than the Alum adjuvant. Therefore, our data have important implications for vaccine adjuvant strategies against SARS-CoV-2 VOCs in older adults.