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)

Purpose Mycobacterium avium complex lung disease (MAC-LD) represents the most common form of nontuberculous mycobacterial lung infection, particularly affecting women and older adults. Clinical management remains challenging, including prediction and differentiation between progressive and non-progressive disease. Overexpression of PD-1 pathways have been reported in progressive disease, and we hypothesize that PD-1 inhibition can restore antigen-specific immune responses detectable by FluoroSpot assay. Methods Peripheral blood mononuclear cells from 22 participants, including progressive and non-progressive MAC-LD patients, healthy controls, and individuals with latent tuberculosis infection (LTBI) were stimulated with nontuberculous mycobacteria and Mycobacterium tuberculosis antigens. Cytokine secretion of interferon-gamma (IFN-γ) and interleukin-2 (IL-2) were quantified using dual FluoroSpot assay, with and without PD-1 blockade. Results Progressive MAC-LD cases demonstrated significant increases in glycopeptidolipid (GPL)- and PPD-stimulated IFN-γ responses following PD-1 blockade, which was not seen in healthy controls, LTBI, or non-progressive MAC-LD patients. After GPL stimulation and in the presence of anti-PD-1, the number of IFN-γ responses increased from 25% to 75% in samples from progressive MAC-LD patients. This supports an association between PD-1–mediated T-cell dysfunction and disease progression. Mycobacterial MTB300 peptide pool antigen failed to discriminate MAC-LD from healthy controls, underscoring antigen specificity. Conclusions Our pilot study demonstrates that IFN-γ FluoroSpot assays, particularly when combining GPL or PPD stimulation and PD-1 inhibition, may help identify progressive MAC-LD. These findings also support other studies reporting that immune checkpoint dysregulation can be present in some patients with progressive and severe MAC-LD patients. Additional studies are warranted to determine its pathogenic role.

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 Non-tubercular mycobacteria (NTM) present a serious challenge in managing lung transplant candidates and recipients. Pretransplant NTM isolation has been associated with post-transplant NTM infection and significantly increased mortality risk. Strategies for managing pre-transplant NTM isolation vary widely in clinical practice. We present a 35-year-old lung transplant candidate from a tuberculosis-endemic country with severe pulmonary hypertension and Eisenmenger Syndrome due to unrepaired atrial septal defect, who underwent bilateral lung transplantation. Two years prior to transplant, she was successfully treated for pulmonary tuberculosis with six months of an unknown regimen in her home country. After moving to the U.S., she received M. tuberculosis (MTB) clearance from her state tuberculosis board, with three negative sputum samples six months prior to transplant. During her transplant evaluation, multi-drug-resistant M. fortuitum complex was isolated from one mycobacterial sputum culture. There was no clinical or radiographic evidence of active lung infection, and no targeted therapies were added. Standard peri-transplant antibiotics (vancomycin, cefepime, and caspofungin) were given. The patient received basilixamab for induction immunosuppression, and tacrolimus, mycophenolate mofetil, and prednisone for maintenance immunosuppression. Explant pathology showed necrotizing granuloma in the right upper lobe with acid-fast bacilli (AFB). The differential diagnosis included non-viable MTB, viable MTB despite prior clearance, or M. fortuitum. Three bronchoscopy washings were obtained in the first week post-transplant and returned negative for MTB by PCR, AFB stain, and culture. In collaboration with the Mycobacteriology laboratory, broad-range PCR testing was performed on the formalin-fixed paraffin-embedded samples from the explanted right lung, which was positive for MTB complex DNA. In total, the patient completed six sputum samples within the year pre-transplant and six respiratory samples within a month post-transplant, all of which returned negative for MTB by PCR, AFB stain, and culture. Blood flow cytometric (FC) immunoprofiling with mycobacterial antigens and controls was conducted (Escalante et al. 2015). The patient's FC antigen-specific activated T-cell profiling was consistent with a reduced risk of latent TB infection (FC CD4+ CD25+CD134+ T-cells (RD1-peptides-nil) = 0.19%). T-cell reactivity to MTB300 and PPD antigens suggested prior MTB, NTM, and/or BCG vaccination exposures. She progressed well without any preventive therapy for LTBI. FC immunoprofiling one year after transplantation showed similar results. She continues to have good pulmonary function and quality of life in her second-year post-transplant without evidence of NTM or MTB infection. Escalante P, et al. Combinatorial Immunoprofiling in Latent Tuberculosis Infection. Am J Respir Crit Care Med. 2015;192(5):605-17. PMCID: PMC4595688.

Abstract RATIONALE: Understanding co-isolation patterns between fungi and other potentially pathogenic microorganisms in the airways of bronchiectasis patients is important for uncovering possible microbial interactions and informing treatment. Although numerous organisms have been identified in respiratory cultures, the specific patterns of their co-isolation are underexplored. OBJECTIVES: To examine the patterns of co-isolation between fungi and bacteria or mycobacteria in respiratory samples from patients with bronchiectasis across a large national health system. METHODS: We reviewed 58,170 respiratory culture tests from 8,194 patients with bronchiectasis (identified using ICD-10-CM codes J47.0, J47.1, and J47.9) across Mayo Clinic. These tests were analyzed for fungal, bacterial, and mycobacterial growth, focusing on co-isolation from the same sample. Chi-square statistics were used to compute p-values. RESULTS: Of all 18,983 samples cultured for fungi, 59% were positive. Of these, 72% yielded yeasts and 40% molds. Among the 11,372 samples cultured for both fungi and bacteria, 681 (6%) showed co-isolation, representing 54% of positive bacterial cultures. The odds of bacterial co-isolation with fungi were 1.4 (95% CI: 1.3-1.6; p < 0.01), driven by yeasts (OR: 1.5, 95% CI: 1.3-1.7; p < 0.01), rather than molds (OR: 1.0, 95% CI: 0.9-1.2; p = 0.8). Pseudomonas species, the most common bacterial isolate, had a higher likelihood of co-isolation with fungi (OR: 1.6, 95% CI: 1.3-1.9; p < 0.01), particularly yeasts (OR: 1.6, 95% CI: 1.4-2.0; p < 0.01). Molds, including those from genera such as aspergillus and penicillium, did not show a significant association with the isolation of pseudomonas. On the other hand, among the 15,859 samples cultured for both fungi and mycobacteria, 1352 (9%) showed co-isolation, representing 62% of positive mycobacterial cultures. Odds of co-isolation were 1.7 (95% CI: 1.5-1.8; p < 0.01). Molds showed a stronger association with isolation of mycobacteria (OR: 1.7, 95% CI: 1.5-1.9; p < 0.01) compared to bacteria, while yeasts also had elevated odds (OR: 1.4, 95% CI: 1.2-1.5). CONCLUSIONS: Distinct patterns of fungal co-isolation with bacteria and mycobacteria have been observed in bronchiectasis, which may influence key aspects of the disease, such as inflammation and mucociliary dysfunction. Advanced metagenomic and immunoprofiling techniques could provide deeper insights into these co-isolation patterns while considering other factors like clinical demographics, previous antibiotic exposure, and disease severity. Understanding whether altering the mycobiome could modify these aspects and improve outcomes remains an important avenue for research.