Citations

Abstract Introduction Screening individuals with latent tuberculosis infection (LTBI) from regions with varying TB endemicity is critical for global TB control. Immune responses to TB differ due to variations in exposure, immune adaptations, and environmental factors. This study evaluated antigen-specific immune responses in untreated LTBI individuals from low- and high-TB-endemic settings. Methods Peripheral blood mononuclear cells from untreated LTBI individuals from low-endemic (USA) and high-TB-endemic settings (Mexico) were stimulated with PPD, MTB300, ESAT-6/CFP-10 (RD1) peptides, mycobacterial glycopeptidolipids (GPL), and controls. We compare flow cytometric immune responses of T-cell intracellular cytokines and activation markers using non-parametric statistical methods. Results We studied age-matched, untreated LTBI individuals who tested IGRA(+)/TST(+) from low-TB-endemic (n = 18) and 18 healthcare workers from a high-TB-endemic settings. IGRA results showed no statistical differences across groups. The frequency of CD3+CD8+IFN-γ+HLA-DR+ and total CD3+TNF-α+ T cells after RD1 stimulation was significantly higher in the high-TB-endemic group (P < 0.05). Additionally, we observed significant increased frequencies in CD3/CD4+TNF-α+HLA-DR+ and CD8+TNF-α+HLA-DR+ T cells stimulated by GPL in the same group, probably associated with nontuberculous mycobacteria (NTM) exposures. Our findings suggest possible recent TB and NTM exposures in healthcare workers from a high-TB-endemic setting, resulted in increased antigen-specific adaptive TNF-α and IFN-γ producing T cells, which are important for pathogen control and immunity. Conclusion We found significant differences in antigen-specific cell immunity, including HLA-DR activated T-cells, a marker of recent antigen encounter, in individuals from a high-TB-endemic settings. These findings underscore the importance of settings-specific immune biomarkers for improving LTBI diagnostics, clinical management, and vaccination trials. Funding Source National Institute of Allergy and Infectious Diseases at the National Institutes of Health Topic Categories Immune Mechanisms of Human Disease (HUM)

Introduction Asymptomatic individuals with negative Interferon-γ release assay (IGRA) and tuberculin skin test (TST) results are often labeled as tuberculosis-unexposed individuals. We hypothesize that flow cytometric (FC) detection of antigen-stimulated T-cells in peripheral blood can differentiate IGRA(-)/TST(-) individuals with and without prior potential M. tuberculosis (Mtb) exposure. Methods We used FC multiparameter profiling of T-cell activation markers in TST/IGRA-negative individuals at risk for Mtb exposure and in unexposed controls. Results We studied 54 IGRA(-)/TST(-) subjects, including 27 individuals at risk for prior Mtb exposure. While quantitative IGRA results were negative in all patients, FC profiling of CD3/CD4 + IFN-γ + HLA-DR + T-cells after stimulation with a pool of Mtb-specific region of difference-1 (RD1) peptides, mycobacterial (PPD and MTB300), or Candida antigens, statistically differentiated between unexposed and potentially exposed individuals (P<0.05). ROC analysis showed PPD and RD1 peptides responses had AUCs >0.7 (sensitivity of 55.5–74% and specificity of 66.6–85.1%). The presence of a polyfunctional RD1-reactive CD3/CD8 + IFN-γ + TNF-α + T-cell subset also significantly differentiated these groups (AUC 0.66). Other T-cell markers demonstrated no significant differences. Conclusions FC detection of antigen-specific IFN-γ + HLA-DR + CD4+T-cells and IFN-γ + TNF-α + CD8 + T-cells can differentiate IGRA(-)/TST(-) individuals at risk of Mtb exposure from unexposed controls. Further validation is needed to determine whether this immunoprofiling approach can improve detection of Mtb infections and identification of unexposed individuals for future biomarker studies and vaccine trails.

Abstract Introduction Emerging evidence suggests that positive airway pressure (PAP) treatment for moderate-to-severe obstructive sleep apnea (OSA) in elderly patients does not improve daytime sleepiness, or quality of life outcomes, despite improving apnea-hypopnea index (AHI). While oral appliance therapy (OAT) is known to be an effective treatment for mild-to-moderate OSA, its efficacy in treatment of elderly patients with severe OSA is unknown. Methods Retrospective chart review of patients ≥ 65 years old with diagnosis of OSA, treated with OAT, who underwent subsequent follow-up sleep testing and clinical assessments, including Epworth Sleepiness Scale (ESS), a measure of daytime sleepiness. Results We studied 66 elderly patients with OSA (31 women, 35 men), including 58 with mild-to-moderate OSA (AHI < 30) and 8 with severe OSA (AHI ≥ 30) treated with OAT. At baseline, patients with mild-to-moderate OSA had a median AHI of 11.6 compared to 41.3 in patients with severe OSA (p < 0.0001). There was no difference in ESS score between patients with mild-to-moderate OSA (median ESS = 8; IQR = 4-12) and severe OSA (median ESS = 6; IQR = 3-9). Following their OSA diagnosis, OAT was offered due to PAP intolerance (n = 32), patient preference (n = 28), or as an alternative treatment option (n = 4). After initiation of OAT, 42 patients with mild-to-moderate and 7 with severe OSA underwent follow-up assessment with home sleep testing (n = 32), oximetry (n = 15), or polysomnography (n = 2). At follow-up assessment, ESS was decreased in patients with mild-to-moderate OSA (median ESS = 5; IQR = 3-8) and severe OSA (median ESS = 5; IQR = 3-7), indicating reduction in daytime sleepiness in response to OAT in both groups. Moreover, 50% of patients with mild-to-moderate OSA and 50% of severe OSA patients saw ≥ 50% reduction in AHI. Conclusion Our study findings suggest that treatment with OAT in mild-to-moderate and severe OSA is tolerable and effective in elderly patients who do not have contraindication for this treatment. OAT should be considered as an alternative treatment specifically for elderly adults with severe OSA not tolerating or improving with PAP therapy. Support (if any)

Abstract Introduction Bronchiectasis (BE) is characterized by recurrent infections and dilated airways and has been associated with recurrent exacerbations and hospitalizations affecting quality of life. Approximately 40-60% of patients with BE have concomitant OSA, with an increased AHI (apnea-hypopnea index) in BE patients with Pseudomonas infections. We hypothesize that patients with BE are less tolerant of PAP therapies, contributing to worsening quality of life related to either condition. We aim to determine differences in PAP adherence and treatment response in patients with BE and OSA compared with a matched OSA-control group. Methods A retrospective cohort analysis was conducted on adult patients evaluated at Mayo Clinic Center for Sleep Medicine between January 2000 to December 2020. Inclusion criteria were patients greater than 18 years old diagnosed with BE and OSA per current guidelines and were prescribed PAP therapy. Control OSA patients were matched to BE/OSA patients by gender, BMI, and AHI severity. Exclusion criteria included cystic fibrosis, hospice enrollment, active lung transplant evaluation, and lack of sleep clinic follow-up. Follow-up visits determined PAP compliance and change in quality-of-life metrics over 3 years. Results We compared 50 patients with BE/OSA with 74 OSA matched controls. The etiology of BE in these cases included COPD (32%) or other etiologies (34%). Baseline characteristics were not statistically different in gender, BMI, and AHI severity across groups. Median treatment follow-up for the BE/OSA group was 3 years [IQR 2 to 4]. Importantly, there was no statistically significant difference in PAP adherence in patients with BE/OSA compared to OSA controls regardless of etiology of BE, but these patients more often required supplemental oxygen therapy. Interestingly, there was a statistically significant increase in MRC and decrease in FEV1 over time in BE patients compliant to therapy. Conclusion There was no significant difference in baseline OSA characteristics, treatment response, and PAP adherence, except for need of oxygen supplementation in BE patients with OSA compared with matched non-BE OSA controls. FEV1 values decreased, and dyspnea score increased in BE patients compliant to PAP therapy; however, future larger studies should include longer-term follow-up to further assess the impact of PAP therapy on BE progression and outcomes. Support (if any)

The optimal detection strategies for effective convalescent immunity after SARS-CoV-2 infection and vaccination remain unclear. The objective of this study was to characterize convalescent immunity targeting the SARS-CoV-2 spike protein using a multiparametric approach. At the beginning of the pandemic, we recruited 30 unvaccinated convalescent donors who had previously been infected with COVID-19 and 7 unexposed asymptomatic controls. Peripheral blood mononuclear cells (PBMCs) were obtained from leukapheresis cones. The humoral immune response was assessed by measuring serum anti-SARS-CoV-2 spike S1 subunit IgG via semiquantitative ELISA, and T-cell immunity against S1 and S2 subunits were studied via IFN-γ enzyme-linked immunosorbent spot (ELISpot) and flow cytometric (FC) activation-induced marker (AIM) assays and the assessment of cytotoxic CD8+ T-cell function (in the subset of HLA-A2-positive patients). No single immunoassay was sufficient in identifying anti-spike convalescent immunity among all patients. There was no consistent correlation between adaptive humoral and cellular anti-spike responses. Our data indicate that the magnitude of anti-spike convalescent humoral and cellular immunity is highly heterogeneous and highlights the need for using multiple assays to comprehensively measure SARS-CoV-2 convalescent immunity. These observations might have implications for COVID-19 surveillance, and the determination of optimal vaccination strategies for emerging variants. Further studies are needed to determine the optimal assessment of adaptive humoral and cellular immunity following SARS-CoV-2 infection, especially in the context of emerging variants and unclear vaccination schedules.

Abstract Optimal detection strategies for effective convalescent immunity after SARS-CoV-2 infection and vaccination remain unclear. The objective of this study was to characterize convalescent immunity targeting the SARS-CoV-2 spike protein using a multiparametric approach. At the beginning of the pandemic, between April 23, 2020, to May 11, 2020, we recruited 30 COVID-19 unvaccinated convalescent donors and 7 unexposed asymptomatic donors. Peripheral blood mononuclear cells (PBMCs) were obtained from leukapheresis cones. The humoral immune response was assessed by measuring serum anti-SARS-CoV-2 spike S1 subunit IgG semiquantitative ELISA and T cell immunity against S1 and S2 subunits were studied by IFN-γ Enzyme-Linked Immune absorbent Spot (ELISpot), flow cytometric (FC) activation-induced marker (AIM) assays and the assessment of cytotoxic CD8+ T-cell function (in the subset of HLA-A2 positive patients). No single immunoassay was sufficient in identifying anti-spike convalescent immunity among all patients. There was no consistent correlation between adaptive humoral and cellular anti-spike responses. Our data indicate that the magnitude of anti-spike convalescent humoral and cellular immunity is highly heterogeneous and highlights the need for using multiple assays to comprehensively measure SARS-CoV-2 convalescent immunity. These observations might have implications for COVID-19 surveillance, and optimal vaccination strategies for emerging variants. Further studies are needed to determine the optimal assessment of adaptive humoral and cellular immunity following SARS-CoV-2 infection, especially in the context of emerging variants and unclear vaccination schedules.