Specific CD4+ T cell phenotypes associate with bacterial control in people who 'resist' infection with Mycobacterium tuberculosis.

A subset of individuals exposed to Mycobacterium tuberculosis (Mtb) that we refer to as 'resisters' (RSTR) show evidence of IFN-γ- T cell responses to Mtb-specific antigens despite serially negative results on clinical testing. Here we found that Mtb-specific T cells in RSTR were clonally expanded, confirming the priming of adaptive immune responses following Mtb exposure. RSTR CD4+ T cells showed enrichment of TH17 and regulatory T cell-like functional programs compared to Mtb-specific T cells from individuals with latent Mtb infection. Using public datasets, we showed that these TH17 cell-like functional programs were associated with lack of progression to active tuberculosis among South African adolescents with latent Mtb infection and with bacterial control in nonhuman primates. Our findings suggested that RSTR may successfully control Mtb following exposure and immune priming and established a set of T cell biomarkers to facilitate further study of this clinical phenotype.

Comprehensive landscape of neutralizing antibody and cell-mediated response elicited by the 1/5 fractional dose of 17DD-YF primary vaccination in adults.

The present study aimed at evaluating the YF-specific neutralizing antibody profile besides a multiparametric analysis of phenotypic/functional features of cell-mediated response elicited by the 1/5 fractional dose of 17DD-YF vaccine, administered as a single subcutaneous injection. The immunological parameters of each volunteer was monitored at two time points, referred as: before (Day 0) [Non-Vaccinated, NV(D0)] and after vaccination (Day 30-45) [Primary Vaccinees, PV(D30-45)]. Data demonstrated high levels of neutralizing antibodies for PV(D30-45) leading to a seropositivity rate of 93%. A broad increase of systemic soluble mediators with a mixed profile was also observed for PV(D30-45), with IFN-γ and TNF-α presenting the highest baseline fold changes. Integrative network mapping of soluble mediators showed increased correlation numbers in PV(D30-45) as compared to NV(D0) (532vs398). Moreover, PV(D30-45) exhibited increased levels of Terminal Effector (CD45RA+CCR7-) CD4+ and CD8+ T-cells and Non-Classical memory B-cells (IgD+CD27+). Dimensionality reduction of Mass Cytometry data further support these findings. A polyfunctional cytokine profile (TNF-α/IFN-γ/IL-10/IL-17/IL-2) of T and B-cells was observed upon in vitro antigen recall. Mapping and kinetics timeline of soluble mediator signatures for PV(D30-45) further confirmed the polyfunctional profile upon long-term in vitro culture, mediated by increased levels of IFN-γ and TNF-α along with decreased production of IL-10. These findings suggest novel insights of correlates of protection elicited by the 1/5 fractional dose of 17DD-YF vaccine.

Disease characteristics and serological responses in patients with differing severity of COVID-19 infection: A longitudinal cohort study in Dhaka, Bangladesh.

BACKGROUND: COVID-19 caused by SARS-CoV-2 ranges from asymptomatic to severe disease and can cause fatal and devastating outcome in many cases. In this study, we have compared the clinical, biochemical and immunological parameters across the different disease spectrum of COVID-19 in Bangladeshi patients. METHODOLOGY/PRINCIPAL FINDINGS: This longitudinal study was conducted in two COVID-19 hospitals and also around the community in Dhaka city in Bangladesh between November 2020 to March 2021. A total of 100 patients with COVID-19 infection were enrolled and classified into asymptomatic, mild, moderate and severe cases (n = 25/group). In addition, thirty age and sex matched healthy participants were enrolled and 21 were analyzed as controls based on exclusion criteria. After enrollment (study day1), follow-up visits were conducted on day 7, 14 and 28 for the cases. Older age, male gender and co-morbid conditions were the risk factors for severe COVID-19 disease. Those with moderate and severe cases of infection had low lymphocyte counts, high neutrophil counts along with a higher neutrophil-lymphocyte ratio (NLR) at enrollment; this decreased to normal range within 42 days after the onset of symptom. At enrollment, D-dimer, CRP and ferritin levels were elevated among moderate and severe cases. The mild, moderate, and severe cases were seropositive for IgG antibody by day 14 after enrollment. Moderate and severe cases showed significantly higher IgM and IgG levels of antibodies to SARS-CoV-2 compared to mild and asymptomatic cases. CONCLUSION/SIGNIFICANCE: We report on the clinical, biochemical, and hematological parameters associated with the different severity of COVID-19 infection. We also show different profile of antibody response against SARS-CoV-2 in relation to disease severity, especially in those with moderate and severe disease manifestations compared to the mild and asymptomatic infection.

Protective Effect of Saffron in Mouse Colitis Models Through Immune Modulation.

BACKGROUND: People with inflammatory bowel disease (IBD) including ulcerative colitis are at risk for colorectal cancer. Despite available effective drugs used to treat IBD, many patients fail or lose response over time with some displaying drug-induced adverse events. Saffron (Crocus sativus) has been reported to have anti-inflammatory properties. Its protective role in IBD has not been explored extensively. AIM: To establish whether saffron treatment alleviates inflammation in experimental colitis. METHODS: Colitis was induced in C57BL/6 mice with 3% DSS and treated with either saffron doses (7.5, 15, 20, 25 mg/kg body weight) or vehicle through daily gavage. On day 11, mice were euthanized and analyzed for gross and microscopic inflammation. Distal colon segments were collected for mRNA and protein expression of HO-1 protein and GPX2, (the downstream targets of NRF-2). Nrf-2 translocation from cytosol to nucleus was confirmed by immunofluorescence, and further Nrf-2 protein expression in nuclear and cytosolic fraction of colon was analyzed by immunoblot. Immune cells were isolated from the lamina propria of mouse colon for flow cytometry-based immunophenotyping. Colitis was also induced in C57BL/6 Ahr knockout and wild type mice to explore the involvement of Ahr-dependent pathways in saffron's protective effect(s). The therapeutic effect of saffron was further validated in another TNBS model of colitis. RESULTS: Saffron 20 mg/kg body weight showed improved colon gross and histology features and led to better body weight, colon length, histology score, and reduced disease activity index (DAI). Saffron significantly decreased pro-inflammatory macrophages (M1), while increasing anti-inflammatory macrophages (M2) and IL10 + dendritic cells. Saffron treatment also enhanced CD3 + T and CD3 + CD8 + T cells followed by increase in different CD3 + CD4 + T cells subsets like CD25 + T cells, FoxP3 + CD25 + regulatory T cells, and CD4 + FOXP3 + CD25-regulatory T cells. Immunoblot analysis showed a significant increase in HO-1/GPX2 protein expression. With saffron treatment, Nrf-2 translocation into nucleus from cytosol also supports the involvement of Nrf-2 and its downstream targets in the protective effect of saffron. Further, we demonstrated that saffron in part exert anti-inflammatory effect through activation of aryl hydrocarbon receptor (AhR)-nuclear factor erythroid 2-related factor 2 (Nrf2)-dependent pathways. CONCLUSION: These data demonstrate saffron's therapeutic potential and its protective role in part via Ahr/Nrf-2 pathways and regulatory innate and adaptive immune cells.

Systems biological assessment of immunity to mild versus severe COVID-19 infection in humans.

Coronavirus disease 2019 (COVID-19) represents a global crisis, yet major knowledge gaps remain about human immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We analyzed immune responses in 76 COVID-19 patients and 69 healthy individuals from Hong Kong and Atlanta, Georgia, United States. In the peripheral blood mononuclear cells (PBMCs) of COVID-19 patients, we observed reduced expression of human leukocyte antigen class DR (HLA-DR) and proinflammatory cytokines by myeloid cells as well as impaired mammalian target of rapamycin (mTOR) signaling and interferon-α (IFN-α) production by plasmacytoid dendritic cells. By contrast, we detected enhanced plasma levels of inflammatory mediators-including EN-RAGE, TNFSF14, and oncostatin M-which correlated with disease severity and increased bacterial products in plasma. Single-cell transcriptomics revealed a lack of type I IFNs, reduced HLA-DR in the myeloid cells of patients with severe COVID-19, and transient expression of IFN-stimulated genes. This was consistent with bulk PBMC transcriptomics and transient, low IFN-α levels in plasma during infection. These results reveal mechanisms and potential therapeutic targets for COVID-19.

The anatomy of single cell mass cytometry data.

Mass cytometry enables the measurement of up to 50 features on single cell. This has catalyzed a shift toward multidimensional data analysis methods, rather than the manual gating strategies as traditionally for in flow cytometry data. This shift means that data scientists are involved in the analysis process to an increasing degree. As the data is analyzed in a more unbiased fashion, where noisy or uninformative observations are not easily excluded, a deeper knowledge of the origin, noise, and modalities of the data is therefore needed to embark on useful data analysis. In this primer, we introduce the idiosyncrasies of mass cytometry data with a focus on the technical properties of how data generated with the CyTOF® system, and the characteristics of protein expression in the cells of the hematopoietic continuum, specifically targeted toward data scientists. We also provide a comprehensive online repository of scripts, tutorials, and example data. © 2018 International Society for Advancement of Cytometry.

Autoimmunity to hypocretin and molecular mimicry to flu in type 1 narcolepsy.

Type 1 narcolepsy (T1N) is caused by hypocretin/orexin (HCRT) neuronal loss. Association with the HLA DQB1*06:02/DQA1*01:02 (98% vs. 25%) heterodimer (DQ0602), T cell receptors (TCR) and other immune loci suggest autoimmunity but autoantigens are unknown. Onset is seasonal and associated with influenza A, notably pandemic 2009 H1N1 (pH1N1) infection and vaccination (Pandemrix). Peptides derived from HCRT and influenza A, including pH1N1, were screened for DQ0602 binding and presence of cognate DQ0602 tetramer-peptide-specific CD4+ T cells tested in 35 T1N cases and 22 DQ0602 controls. Higher reactivity to influenza pHA273-287 (pH1N1 specific), PR8 (H1N1 pre-2009 and H2N2)-specific NP17-31 and C-amidated but not native version of HCRT54-66 and HCRT86-97 (HCRTNH2) were observed in T1N. Single-cell TCR sequencing revealed sharing of CDR3ß TRBV4-2-CASSQETQGRNYGYTF in HCRTNH2 and pHA273-287-tetramers, suggesting molecular mimicry. This public CDR3ß uses TRBV4-2, a segment modulated by T1N-associated SNP rs1008599, suggesting causality. TCR-α/ß CDR3 motifs of HCRT54-66-NH2 and HCRT86-97-NH2 tetramers were extensively shared: notably public CDR3α, TRAV2-CAVETDSWGKLQF-TRAJ24, that uses TRAJ24, a chain modulated by T1N-associated SNPs rs1154155 and rs1483979. TCR-α/ß CDR3 sequences found in pHA273-287, NP17-31, and HCRTNH2 tetramer-positive CD4+ cells were also retrieved in single INF-γ-secreting CD4+ sorted cells stimulated with Pandemrix, independently confirming these results. Our results provide evidence for autoimmunity and molecular mimicry with flu antigens modulated by genetic components in the pathophysiology of T1N.