Enhanced Severe Acute Respiratory Syndrome Coronavirus 2 Antigen-Specific Systemic Immune Responses in Multisystem Inflammatory Syndrome in Children and Reversal After Recovery.

BACKGROUND: Multisystem inflammatory syndrome in children (MIS-C) presents with inflammation and pathology of multiple organs in the pediatric population in the weeks following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. METHODS: We characterized the SARS-CoV-2 antigen-specific cytokine and chemokine responses in children with MIS-C, coronavirus disease 2019 (COVID-19), and other infectious diseases. RESULTS: MIS-C is characterized by elevated levels of type 1 (interferon-γ, interleukin [IL] 2), type 2 (IL-4, IL-13), type 17 (IL-17), and other proinflammatory cytokines (IL-1α, IL-6, IL-12p70, IL-18, and granulocyte-macrophage colony-stimulating factor) in comparison to COVID-19 and other infectious diseases following stimulation with SARS-CoV-2-specific antigens. Similarly, upon SARS-CoV-2 antigen stimulation, CCL2, CCL3, and CXCL10 chemokines were significantly elevated in children with MIS-C in comparison to the other 2 groups. Principal component analysis based on these cytokines and chemokines could clearly distinguish MIS-C from both COVID-19 and other infections. In addition, these responses were significantly diminished and normalized 6-9 months after recovery. CONCLUSIONS: Our data suggest that MIS-C is characterized by an enhanced production of cytokines and chemokines that may be associated with disease pathogenesis.

Effect of SARS-CoV-2 seropositivity on antigen - specific cytokine and chemokine responses in latent tuberculosis.

SARS-CoV-2 and latent Mycobacterium tuberculosis infection are both highly co-prevalent in many parts of the globe. Whether exposure to SARS-CoV-2 influences the antigen specific immune responses in latent tuberculosis has not been investigated. We examined the baseline, mycobacterial antigen and mitogen induced cytokine and chemokine responses in latent tuberculosis (LTBI) individuals with or without SARS-CoV-2 seropositivity, LTBI negative individuals with SARS-CoV-2 seropositivity and healthy control (both LTBI and SARS-CoV-2 negative) individuals. Our results demonstrated that LTBI individuals with SARS-CoV-2 seropositivity (LTBI+/IgG +) were associated with increased levels of unstimulated and TB-antigen stimulated IFNγ, IL-2, TNFα, IL-17, IL-1ß, IL-6, IL-12, IL-4, CXCL1, CXCL9 and CXCL10 when compared to those without seropositivity (LTBI+/IgG-). In contrast, LTBI+/IgG+ individuals were associated with decreased levels of IL-5 and IL-10. No significant difference in the levels of cytokines/chemokines was observed upon mitogen stimulation between the groups. SARS-CoV-2 seropositivity was associated with enhanced unstimulated and TB-antigen stimulated but not mitogen stimulated production of cytokines and chemokines in LTBI+ compared to LTBI negative individuals. Finally, most of these significant differences were not observed when LTBI negative individuals with SARS-CoV-2 seropositivity and controls were examined. Our data clearly demonstrate that both baseline and TB - antigen induced cytokine responses are augmented in the presence of SARS-CoV-2 seropositivity, suggesting an augmenting effect of prior SARS-CoV-2 infection on the immune responses of LTBI individuals.

'Dirty foreigners' are to blame for COVID-19: impacts of COVID stress syndrome on quality of life and gratitude among Singaporean adults.

The outbreak of COVID-19 has caused widespread emotional distress. The current study sought to ascertain the impact of COVID stress syndrome on quality of life and gratitude. The COVID-19 Stress Scale, COVID-19 Quality of Life Scale, and Gratitude Resentment and Appreciation Scale were administered to 199 Singaporeans. Data were collected online using convenience sampling between December 2020 and March 2021. Pearson correlations and hierarchical regression analyses were used to test the research hypotheses. The results showed that fear of spreading SARSCoV2 by foreigners was the most stressful fear among Singaporeans (M = 2.59), while traumatic stress by COVID-19 was the least stressful fear (M = 0.16). COVID stress syndrome was positively correlated with negative quality of life (r ranged from .25 to .66) and negatively correlated with gratitude (r ranged from -.29 to -.14). Xenophobia was also found to be the most influential factor in reducing quality of life (ß = .52) and gratitude (ß = -.37) during the pandemic. Study findings demonstrate how COVID-19 increases Singaporeans' xenophobic attitudes towards foreigners, making them more vulnerable to the pandemic.

Plasma Chemokines Are Baseline Predictors of Unfavorable Treatment Outcomes in Pulmonary Tuberculosis.

BACKGROUND: Plasma chemokines are biomarkers of greater disease severity, higher bacterial burden, and delayed sputum culture conversion in pulmonary tuberculosis (PTB). Whether plasma chemokines could also serve as biomarkers of unfavorable treatment outcomes in PTB is not known. METHODS: A cohort of newly diagnosed, sputum smear- and culture-positive adults with drug-sensitive PTB were recruited under the Effect of Diabetes on Tuberculosis Severity study in Chennai, India. Plasma chemokine levels measured before treatment initiation were compared between 68 cases with unfavorable outcomes (treatment failure, death, or recurrence) and 136 control individuals who had recurrence-free cure. A second validation cohort comprising newly diagnosed, culture-positive adults with drug-sensitive TB was used to measure plasma chemokine levels in 20 cases and 40 controls. RESULTS: Six chemokines (CCL2, CCL3, CCL4, CXCL8, CXCL10, and CX3CL1) were associated with increased risk, while CXCL1 was associated with decreased risk of unfavorable outcomes in unadjusted and adjusted analyses in the test cohort. Similarly, CCL3, CXCL8, and CXCL10 were associated with increased risk of unfavorable treatment outcomes in the validation cohort. Receiver operating characteristic analysis revealed that combinations of CCL3, CXCL8, and CXCL10 exhibited very high sensitivity and specificity in differentiating cases vs controls. CONCLUSIONS: Our study reveals a plasma chemokine signature that can be used as a novel biomarker for predicting adverse treatment outcomes in PTB.

Antibody responses to the BBV152 vaccine in individuals previously infected with SARS-CoV-2: A pilot study.

Background & objectives: Vaccination against SARS-CoV-2 is a recommendation from the World Health Organization as the foremost preference in the current situation to control the COVID-19 pandemic. BBV152 is one of the approved vaccines against SARS-CoV-2 in India. In this study, we determined SARS-CoV-2-specific antibody levels at day 0 (baseline, before vaccination), day 28 ± 2 post-first dose (month 1) and day 56 ± 2 post-first dose (month 2) of BBV152 whole-virion-inactivated SARS-CoV-2 recipients, and compared the antibody responses of individuals with confirmed pre-vaccination SARS-CoV-2 infection to those individuals without prior evidence of infection. Methods: Blood samples were collected from 114 healthcare professionals and frontline workers who received BBV152 vaccine from February to May & June 2021. Prior infection with SARS-CoV-2 was determined at baseline. Serum samples were used to estimate SARS-CoV-2 nucleoprotein-specific IgG [IgG (N)], spike protein-specific IgG [IgG (S)] and neutralizing antibodies (NAb). Results: Participants with previous SARS-CoV-2 infection after a single vaccine dose elicited IgG (N) and IgG (S) antibody levels along with NAb binding inhibition responses levels were similar to infection-naïve vaccinated participants who had taken two doses of vaccine. Interpretation & conclusions: Our preliminary data suggested that a single dose of BBV152-induced humoral immunity in previously infected individuals was equivalent to two doses of the vaccine in infection-naïve individuals. However, these findings need to be confirmed with large sized cohort studies.

Heterogeneity in the cytokine profile of tuberculosis - diabetes co-morbidity.

Tuberculosis - diabetes (TB-DM) co-morbidity is characterized by heterogeneity in clinical and biochemical parameters between newly diagnosed diabetic individuals with TB (TB-NDM) and known diabetic individuals at incident TB (TB-KDM). However, the immunological profile underlying this heterogeneity is not explored. To identify the cytokine profiles in TB-NDM and TB-KDM individuals, we examined the plasma cytokine levels as well as TB-antigen stimulated levels of pro-inflammatory cytokines. TB-KDM individuals exhibit significantly higher levels of IFNγ, IL-2, TNFα, IL-17A, IL-1α, IL-1ß and IL-6 in comparison to TB-NDM, TB alone and DM alone individuals. TB-NDM individuals are characterized by significantly lower levels of blood glucose and glycated hemoglobin in comparison to TB-KDM with both groups exhibiting a significant lowering of glycated hemoglobin levels at 6  months of anti-tuberculosis therapy (ATT). TB-NDM individuals are characterized by significantly diminished - unstimulated levels of IFNγ, IL-2, TNFα, IL-17A, IL-1α, IL-1ß and IL-12 at pre-treatment, of IFNγ, IL-2 and IL-1α at 2  months of ATT and IL-2 at post-treatment in comparison to TB-KDM. TB-NDM individuals are also characterized by significantly diminished TB-antigen stimulated levels of IFNγ, IL-2, TNFα, IL-17A, IL-17F, IL-1α, IL-1ß and/or IL-6 at pre-treatment and at 2  months of ATT and IFNγ, IL-2, IL-1α and IL-1ß at post-treatment. In addition, TB-NDM individuals are characterized by significantly diminished mitogen - stimulated levels of IL-17F and IL-6 at pre-treatment and IL-6 alone at 6 months of ATT. Therefore, our data reveal considerable heterogeneity in the immunological underpinnings of TB-DM co-morbidity. Our data also suggest that TB-NDM exhibits a characteristic profile, which is both biochemically and immunologically distinct from TB-KDM.

Elevated circulating levels of monocyte activation markers among tuberculosis patients with diabetes co-morbidity.

Alteration in the frequency of monocyte subsets is a hallmark of tuberculosis-diabetes co-morbidity (TB-DM). To study this association, we examined the plasma levels of sCD14, sCD163, C-reactive protein (CRP) and soluble tissue factor (sTF) in individuals with TB-DM, TB or diabetes mellitus (DM), and in healthy controls (HC). Circulating levels of sCD14, sCD163 and sTF were significantly increased in TB-DM and DM compared with TB and HC; however, CRP was significantly increased in TB-DM and TB compared with DM and HC. During longitudinal follow up, sCD14, CRP and sTF levels remained significantly increased in TB-DM compared with TB from baseline (pre-treatment), during treatment (2nd month) and at the completion (6th month) of anti-TB treatment (ATT), whereas sCD163 was significantly higher in TB-DM compared with TB only at baseline. Moreover, the levels of sCD14 and sCD163 were significantly higher in TB-DM individuals with bilateral and cavitary disease and exhibited a significant positive relationship with bacterial burden. Levels of sCD14, sCD163 and CRP exhibited a positive relationship with HbA1c levels. Within the TB-DM group, those with known diabetes before incident TB (KDM) exhibited significantly higher levels of sCD14 and sCD163 compared with individuals with newly diagnosed DM with TB (NDM). Finally, KDM individuals on metformin treatment exhibited significantly lower levels of sCD14, sCD163 and CRP compared with those on non-metformin-containing regimens. Our data demonstrate that systemic monocyte activation marker levels reflect baseline disease severity and extent in TB-DM, differentiate KDM from NDM and are modulated by ATT and metformin therapy.

Systemic RAGE ligands are upregulated in tuberculosis individuals with diabetes co-morbidity and modulated by anti-tuberculosis treatment and metformin therapy.

BACKGROUND: Ligands of the receptor for advanced glycation end products (RAGE) are key signalling molecules in the innate immune system but their role in tuberculosis-diabetes comorbidity (TB-DM) has not been investigated. METHODS: We examined the systemic levels of soluble RAGE (sRAGE), advanced glycation end products (AGE), S100A12 and high mobility group box 1 (HMGB1) in participants with either TB-DM, TB, DM or healthy controls (HC). RESULTS: Systemic levels of AGE, sRAGE and S100A12 were significantly elevated in TB-DM and DM in comparison to TB and HC. During follow up, AGE, sRAGE and S100A12 remained significantly elevated in TB-DM compared to TB at 2nd month and 6th month of anti-TB treatment (ATT). RAGE ligands were increased in TB-DM individuals with bilateral and cavitary disease. sRAGE and S100A12 correlated with glycated hemoglobin levels. Within the TB-DM group, those with known diabetes (KDM) revealed significantly increased levels of AGE and sRAGE compared to newly diagnosed DM (NDM). KDM participants on metformin treatment exhibited significantly diminished levels of AGE and sRAGE in comparison to those on non-metformin regimens. CONCLUSIONS: Our data demonstrate that RAGE ligand levels reflect disease severity and extent in TB-DM, distinguish KDM from NDM and are modulated by metformin therapy.

BCG vaccination is associated with longitudinal changes in systemic eicosanoid levels in elderly individuals: A secondary outcome analysis.

We investigated how BCG vaccination affects the levels of certain eicosanoids, namely Leukotriene B4, 15-epimer of LXA4, prostaglandin F2, Lipoxin A4, Prostaglandin E2 and Resolvin D1 in the plasma of healthy elderly individuals (aged 60-80) before vaccination, one month post-vaccination (M1), and six months post-vaccination (M6). This study is part of the clinical trial "BCG Vaccine Study: Reducing COVID-19 Impact on the Elderly in Indian Hotspots," registered in the clinical trial registry (NCT04475302). While some primary outcomes have been previously reported, this analysis delves into the immunological outcomes. Our findings indicate that BCG vaccination leads to reduced plasma levels of 15-epi-LXA4, LXA4, PGE2, and Resolvin D1 at both M1 and M6. In contrast, there is a notable increase in circulating levels of LTB4 at these time points following BCG vaccination. This underscores the immunomodulatory effects of BCG vaccination and hints at its potential to modulate immune responses by dampening inflammatory reactions.

Effect of Metformin on systemic chemokine responses during anti-tuberculosis chemotherapy.

BACKGROUND: Metformin (MET), by boosting immunity, has been suggested as a host-adjunctive therapy to anti-tuberculosis treatment (ATT). METHODS: We evaluated whether adding MET to the standard ATT can alter the host chemokine response. We investigated the influence of metformin on the plasma levels of a wide panel of chemokines in a group of active tuberculosis patients before treatment, at 2nd month of ATT and at 6-months of ATT as part of our clinical study to examine the effect of metformin on ATT. RESULTS: Our results demonstrated that addition of metformin resulted in diminished CC (CCL1 and CCL3) and CXC (CXCL-2 and CXCL-10) chemokines in MET arm as compared to non-MET arm at the 2nd month and 6th month of ATT. In addition to this, MET arm showed significantly diminished chemokines in individuals with high bacterial burden and cavitary disease. CONCLUSION: Our current data suggest that metformin alters chemokines responses that could potentially curb excessive inflammation during ATT.

Chitinase and indoleamine 2, 3-dioxygenase are prognostic biomarkers for unfavorable treatment outcomes in pulmonary tuberculosis.

Introduction: Chitinase, Indoleamine 2,3-dioxygenesae-1 (IDO-1) and heme oxygenase-1 (HO-1) are candidate diagnostic biomarkers for tuberculosis (TB). Whether these immune markers could also serve as predictive biomarkers of unfavorable treatment outcomes in pulmonary TB (PTB) is not known. Methods: A cohort of newly diagnosed, sputum culture-positive adults with drug-sensitive PTB were recruited. Plasma chitinase protein, IDO protein and HO-1 levels measured before treatment initiation were compared between 68 cases with unfavorable outcomes (treatment failure, death, or recurrence) and 108 control individuals who had recurrence-free cure. Results: Plasma chitinase and IDO protein levels but not HO-1 levels were lower in cases compared to controls. The low chitinase and IDO protein levels were associated with increased risk of unfavourable outcomes in unadjusted and adjusted analyses. Receiver operating characteristic analysis revealed that chitinase and IDO proteins exhibited high sensitivity and specificity in differentiating cases vs controls as well as in differentiating treatment failure vs controls and recurrence vs controls, respectively. Classification and regression trees (CART) were used to determine threshold values for these two immune markers. Discussion: Our study revealed a plasma chitinase and IDO protein signature that may be used as a tool for predicting adverse treatment outcomes in PTB.

BCG vaccination induces enhanced humoral responses in elderly individuals.

BACKGROUND: Studies have reported the beneficial effects of Bacillus Calmette Guerin (BCG) vaccination, including non-specific cross-protection against other infectious diseases. METHODS: We investigated the impact of BCG vaccination on the frequencies of B cell subsets as well as total antibody levels in healthy elderly individuals at one month post vaccination. We also compared the above-mentioned parameters in post-vaccinated individuals to unvaccinated controls. RESULTS: Our results demonstrate that BCG vaccination induced enhanced frequencies of immature, classical and activated memory B cells and plasma cells and diminished frequencies of naïve and atypical memory B cells. BCG vaccination induced significantly increased levels of total IgG subclass isotypes compared to baseline. Similarly, all of the above parameters were significantly higher in vaccinated individuals compared to unvaccinated controls. CONCLUSION: BCG vaccination was associated with enhanced B cell subsets, suggesting its potential utility by enhancing heterologous immunity.

Low body mass index is associated with diminished plasma cytokines and chemokines in both active and latent tuberculosis.

Introduction: Low body mass index (BMI) is a major risk factor for tuberculosis (PTB). Low BMI can impair the immune system and thus might affect TB incidence. Methods: We examined the plasma levels of Type 1, Type 17, pro-inflammatory, Type 2 and regulatory cytokines and CC and CXC chemokines in PTB and latent TB (LTB) individuals with low BMI (LBMI) or normal BMI (NBMI). Results: Our data show that PTB is associated with significantly lower levels of IFNγ, TNFα, IL-2, IL-17A, IL-6, IL-12, IL-4 and IL-5 cytokines but significantly higher levels of IL-10, TGFß and GM-CSF in LBMI compared to NBMI. Similarly, PTB is also associated with significantly lower levels of CCL2, CCL3, CCL11, CXCL1, CXCL9 and CXCL10 chemokines in LBMI compared to NBMI. Our data reveals that LTB is associated with significantly lower levels of IFNγ, TNFα, IL-2, IL1ß, IL-12, IL-13 cytokines but significantly higher levels of IL-10, TGFß, IL-4 and IL-22 in LBMI compared to NBMI. Similarly, LTB is also associated with significantly lower levels of CCL2, CXCL1, CXCL9 and CXCL10 and significantly higher levels of CCL1, CCL3, and CCL4 in LBMI compared to NBMI. Conclusion: Thus, LBMI has a major impact on the cytokine and chemokine milieu of both PTB and LTB and might predispose to the increased risk of tuberculosis by this immunomodulatory effect.

Immune Profiles in Multisystem Inflammatory Syndrome in Children with Cardiovascular Abnormalities.

BACKGROUND: Multisystem inflammatory syndrome in children (MIS-C), a sequela of severe acute respiratory syndrome coronavirus-2 infection (SARS-CoV2), has been progressively reported worldwide, with cardiac involvement being a frequent presentation. Although the clinical and immunological characteristics of MIS-C with and without cardiac involvement have been described, the immunological differences between cardiac and non-cardiac MIS-C are not well understood. METHODS: The levels of type 1, type 2, type 17, other proinflammatory cytokines and CC chemokines and CXC chemokines were measured using the Magpix multiplex cytokine assay system in MIS-C children with MIS-C cardiac (MIS-C (C) (n = 88)) and MIS-C non-cardiac (MIS-C (NC) (n = 64)) abnormalities. RESULTS: MIS-C children with cardiac manifestations presented with significantly increased levels of cytokines such as IFN-γ, IL-2, TNFα, IL-5, IL-1α, IL-1ß, IL-6, IL-10 and IL-12p70 and chemokines such as CCL2, CCL3, CCL11 and CXCL10 in comparison to MIS-C children without cardiac manifestations. Clustering analysis revealed that cytokines and chemokines could clearly distinguish MIS-C children with and without cardiac manifestations. In addition, these responses significantly diminished and normalized 9 months after treatment. CONCLUSIONS: This is one of the first studies characterizing and differentiating systemic inflammation in MIS-C with and without cardiac involvement from a low- and middle-income country (LMIC). Our study contributes to the existing body of evidence and advances our knowledge of the immunopathogenesis of MIS-C in children.

Multisystem inflammatory syndrome in children characterized by enhanced antigen-specific T-cell expression of cytokines and its reversal following recovery.

Background: Multisystem inflammatory syndrome (MIS) in children is considered to be a post-infectious complication of COVID-19. T-cell responses in children with this condition have not been well-studied. Methods: We aimed to study the immune responses in children with MIS in comparison to children with acute COVID-19 and children with other infections. Whole blood was stimulated with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)-specific antigens and flow cytometry was performed to examine CD4+ and CD8+ T-cell responses. Results: Children with MIS had higher frequencies of CD4+ and CD8+ T cells expressing cytokines at baseline and upon SARS-CoV-2 antigen-specific stimulation in comparison to children with COVID-19 and/or other infections. Children with COVID-19 also exhibited higher frequencies of CD4+ and CD8+ T cells expressing cytokines at baseline and upon SARS-CoV-2 antigen-specific stimulation in comparison to children with other infections. At 6-9 months following treatment and recovery, this enhanced response against SARS-CoV-2 antigens was down modulated in children with MIS. Conclusion: Our study, therefore, provides evidence of enhanced activation of CD4+ and CD8+ T-cell responses in children with MIS and reversal following recovery.

Inactivated COVID-19 vaccines: durability of Covaxin/BBV152 induced immunity against variants of concern.

BACKGROUND: Covaxin/BBV152 is one of the most widely used vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and one of the few vaccines used extensively in low- and middle-income countries (LMIC). METHODS: We investigated the effect of Covaxin on the SARS-CoV-2 specific IgG and IgA and neutralizing antibody (NAb) levels at baseline (M0) and at Months 1 (M1), 2 (M2), 3 (M3), 4 (M4), 6 (M6) and 12 (M12) following vaccination in healthcare workers. In addition, we also examined the NAb levels against variant lineages of B.1.617.2 (Delta, India), B.1.617.2.1 (Delta Plus, India), B.1.351 (Beta, SA), B.1.1.7 (Alpha, UK) and B.1.1.529 (Omicron). RESULTS: Covaxin induces enhanced SARS-CoV-2 binding antibodies of IgG and IgA responses against both spike (S) and nucleocapsid (N) antigens at M1, M2, M3, M4, M6 and M12 in comparison with M0. Our data also reveal that NAb levels against the ancestral strain (Wuhan, wild type) are elevated and sustained at M1, M2, M3, M4, M6 and M12 in comparison with M0 and against variant lineages of B.1.617.2 (Delta, India), B.1.617.2.1 (Delta Plus, India), B.1.351 (Beta, SA) and B.1.1.7 (Alpha, UK) are elevated at M3, M6 and M12 in comparison with M0. However, NAb levels against B.1.1.529 (Omicron) was consistently below the limit of detection except at M12. CONCLUSION: Thus, Covaxin induces an enhanced humoral immune response, with persistence till at least 12 months post-vaccination against most SARS-CoV-2 variants.

Role of matrix metalloproteinases in multi-system inflammatory syndrome and acute COVID-19 in children.

Introduction: Multisystem Inflammatory Syndrome in children (MIS-C) is a serious inflammatory sequela of SARS-CoV2 infection. The pathogenesis of MIS-C is vague and matrix metalloproteinases (MMPs) may have an important role. Matrix metalloproteinases (MMPs) are known drivers of lung pathology in many diseases. Methods: To elucidate the role of MMPs in pathogenesis of pediatric COVID-19, we examined their plasma levels in MIS-C and acute COVID-19 children and compared them to convalescent COVID-19 and children with other common tropical diseases (with overlapping clinical manifestations). Results: Children with MIS-C had elevated levels of MMPs (P < 0.005 statistically significant) in comparison to acute COVID-19, other tropical diseases (Dengue fever, typhoid fever, and scrub typhus fever) and convalescent COVID-19 children. PCA and ROC analysis (sensitivity 84-100% and specificity 80-100%) showed that MMP-8, 12, 13 could help distinguish MIS-C from acute COVID-19 and other tropical diseases with high sensitivity and specificity. Among MIS-C children, elevated levels of MMPs were seen in children requiring intensive care unit admission as compared to children not needing intensive care. Similar findings were noted when children with severe/moderate COVID-19 were compared to children with mild COVID-19. Finally, MMP levels exhibited significant correlation with laboratory parameters, including lymphocyte counts, CRP, D-dimer, Ferritin and Sodium levels. Discussion: Our findings suggest that MMPs play a pivotal role in the pathogenesis of MIS-C and COVID-19 in children and may help distinguish MIS-C from other conditions with overlapping clinical presentation.

Enhanced SARS-CoV-2-Specific CD4+ T Cell Activation and Multifunctionality in Late Convalescent COVID-19 Individuals.

Background: Examination of CD4+ T cell responses during the natural course of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection offers useful information for the improvement of vaccination strategies against this virus and the protective effect of these T cells. Methods: We characterized the SARS-CoV-2-specific CD4+ T cell activation marker, multifunctional cytokine and cytotoxic marker expression in recovered coronavirus disease 2019 (COVID-19) individuals. Results: CD4+ T-cell responses in late convalescent (>6 months of diagnosis) individuals are characterized by elevated frequencies of activated as well as mono, dual- and multi-functional Th1 and Th17 CD4+ T cells in comparison to early convalescent (<1 month of diagnosis) individuals following stimulation with SARS-CoV-2-specific antigens. Similarly, the frequencies of cytotoxic marker expressing CD4+ T cells were also enhanced in late convalescent compared to early convalescent individuals. Conclusion: Our findings from a low-to middle-income country suggest protective adaptive immune responses following natural infection of SARS-CoV-2 are elevated even at six months following initial symptoms, indicating the CD4+ T cell mediated immune protection lasts for six months or more in natural infection.

Effect of BCG vaccination on proinflammatory responses in elderly individuals.

We investigated the influence of Bacillus Calmette-Guérin (BCG) vaccination on the unstimulated plasma levels of a wide panel of cytokines, chemokines, acute-phase proteins (APPs), matrix metalloproteinases (MMPs), and growth factors in a group of healthy elderly individuals (age, 60 to 80 years) at baseline (before vaccination) and 1 month after vaccination as part of our clinical study to examine the effect of BCG on COVID-19. Our results demonstrated that BCG vaccination resulted in diminished plasma levels of types 1, 2, and 17 and other proinflammatory cytokines and type 1 interferons. BCG vaccination also resulted in decreased plasma levels of CC, CXC chemokines, APPs, MMPs, and growth factors. Plasma levels of the aforementioned parameters were significantly lower in vaccinated individuals when compared to unvaccinated control individuals. Thus, our study demonstrates the immunomodulatory properties of BCG vaccination and suggests its potential utility in nonspecific vaccination of COVID-19 by down-modulating pathogenic inflammatory responses.

Acute Phase Proteins Are Baseline Predictors of Tuberculosis Treatment Failure.

Systemic inflammation is a characteristic feature of pulmonary tuberculosis (PTB). Whether systemic inflammation is associated with treatment failure in PTB is not known. Participants, who were newly diagnosed, sputum smear and culture positive individuals with drug-sensitive PTB, were treated with standard anti-tuberculosis treatment and classified as having treatment failure or microbiological cure. The plasma levels of acute phase proteins were assessed at baseline (pre-treatment). Baseline levels of C-reactive protein (CRP), alpha-2 macroglobulin (a2M), Haptoglobin and serum amyloid P (SAP) were significantly higher in treatment failure compared to cured individuals. ROC curve analysis demonstrated the utility of these individual markers in discriminating treatment failure from cure. Finally, combined ROC analysis revealed high sensitivity and specificity of 3 marker signatures comprising of CRP, a2M and SAP in distinguishing treatment failure from cured individuals with a sensitivity of 100%, specificity of 100% and area under the curve of 1. Therefore, acute phase proteins are very accurate baseline predictors of PTB treatment failure. If validated in larger cohorts, these markers hold promise for a rapid prognostic testing for adverse treatment outcomes in PTB.