Onn Min Kon

T Cells and Chronic Asthma

There is increasing evidence that the asthma process is driven’ and maintained by persistence of a subset of chronically activated T memory cells, sensitized against allergenic, occupational or viral antigens which home’ to the lung after antigen exposure or viral infection. In general, allergens induce a CD4 T helper (Th) cell response, whereas viruses recognize CD8+ cytotoxic (Tc) T cells. In the asthmatic airways, there are CD4+ and, to a lesser number CD8+ cells with a type 2 cytokine phenotype (i.e., Th–2 and Tc–2 type). These cells produce interleukin (IL) 3 and 5 and granulocyte–macrophage colony–stimulating factor which recruit, mobilize and activate eosinophils for subsequent mucosal damage, as well as IL–4, an essential cofactor for local or generalized IgE production. This leads to epithelial shedding, mucus hypersecretion and bronchial muscle contraction. Thus, although the eosinophil may damage the mucosal surfaces in asthma, its function appears to be under T cell control. Support for this hypothesis includes: (1) activated T cells and their products can be identified in biopsies from the major variants of the disease (atopic, non–atopic and occupational asthma); (2) colocalization of mRNA for type 2 cytokines to CD4+ and CD8+ cells in atopic and non–atopic asthma; (3) the presence of activated cytokine–producing T cells in corticosteroid–resistant asthma; (4) the association of disease severity with type 2 cytokines, especially IL–5; and (5) the efficacy of cyclosporin A and a monoclonal anti–CD4 in chronic steroid–dependent disease. Inhibitors and/or antagonists directed against more precise T cell associated molecular targets hold promise for the future treatment of chronic asthma.

The effects of an anti-CD4 monoclonal antibody, keliximab, on peripheral blood CD4+ T-cells in asthma

CD4+ T-cells are likely to be involved as a source of pro-inflammatory cytokines in asthma. This study assessed the effects of an infusion of keliximab (IDEC CE9.1), an anti-CD4+ monoclonal antibody, on peripheral blood CD4+ T-cells in corticosteroid-dependent asthmatics. Three cohorts of patients (termed C0.5: n=6, C1.5: n=5, and C3.0: n=5) received a single infusion of 0.5, 1.5 or 3.0 mg x kg(-1), respectively, with a fourth receiving placebo (Cpl: n=6), and were followed-up for 4 weeks. By flow cytometry in peripheral blood, pre- and postinfusion assessment was made of: a) CD4 and CD8 counts and mean fluorescence; b) CD25, human leukocyte antigen-DR (HLA-DR), CD45RO and CD45RA expression on CD4+ T-cells; and c) interferon (IFN)-gamma, interleukin (IL)-4 and IL-5 expression in CD4+ T-cells. Keliximabs in vitro effects on allergen-specific peripheral blood mononuclear cells (PBMC) proliferation in atopic asthmatics were also evaluated. There was a significant increase in lung function (peak expiratory flow rate) in the C3.0 group. Following infusion in C0.5, C1.5 and C3.0 but not Cpl: 1) the CD4, but not CD8 count was significantly decreased; 2) there was total loss of Leu3a staining; 3) there were significant reductions in the mean fluorescence of OKT4 binding; and 4) there were significant reductions in the numbers of CD25, HLA-DR, CD45RO and CD45RA/CD4+ cells. There were no changes in CD4+ cell expression of IFN-gamma, IL-4 or IL-5. Keliximab caused a significant reduction in T-cell proliferation as compared to a control monoclonal antibody. Keliximab, as an anti-CD4 monoclonal antibody, leads to a transient reduction in the number of CD4+ T-cells and modulation of CD4+ receptor expression in severe asthmatics. The effects of keliximab may be mediated through a decrease in CD4+ surface expression and T-lymphocyte numbers, in addition to a reduction in allergen-induced proliferation.

RSV-specific airway resident memory CD8+ T cells and differential disease severity after experimental human infection

In animal models, resident memory CD8+ T (Trm) cells assist in respiratory virus elimination but their importance in man has not been determined. Here, using experimental human respiratory syncytial virus (RSV) infection, we investigate systemic and local virus-specific CD8+ T-cell responses in adult volunteers. Having defined the immunodominance hierarchy, we analyse phenotype and function longitudinally in blood and by serial bronchoscopy. Despite rapid clinical recovery, we note surprisingly extensive lower airway inflammation with persistent viral antigen and cellular infiltrates. Pulmonary virus-specific CD8+ T cells display a CD69+CD103+ Trm phenotype and accumulate to strikingly high frequencies into convalescence without continued proliferation. While these have a more highly differentiated phenotype, they express fewer cytotoxicity markers than in blood. Nevertheless, their abundance before infection correlates with reduced symptoms and viral load, implying that CD8+ Trm cells in the human lung can confer protection against severe respiratory viral disease when humoral immunity is overcome.

Blood eosinophils from atopic donors express messenger RNA for the α, β, and γ subunits of the high-affinity IgE receptor (FcϵRI) and intracellular, but not cell surface, α subunit protein

Abstract Background: Blood eosinophils from hypereosinophilic donors were previously reported to possess the functional high-affinity IgE receptor (FcϵRI), so providing a potential mechanism to account for eosinophil degranulation in atopic allergic disease. Furthermore, tissue eosinophils from allergic tissue reactions were shown to be mRNA + for the α, β, and γ subunits of FcϵRI and gave positive immunostaining with an anti-FcϵRI-α antibody. Recent studies, however, revealed negative surface staining on peripheral blood eosinophils, but intracellular FcϵRI-α protein was identified by Western blot analysis. Objective: Our purpose was to examine on peripheral blood eosinophils from atopic subjects (1) surface expression and mRNA for FcϵRI-α, (2) up-regulation of FcϵRI-α by allergy-associated tissue factors, and (3) FcϵRI-α–dependent release of eosinophil peroxidase (EPO). Methods: We measured (1) FcϵRI mRNA expression by in situ hybridization, (2) FcϵRI-α by flow cytometry and immunocytochemistry (with use of nonpermeabilized and permeabilized cells), and (3) FcϵRI-α–dependent release of EPO. Results: Eosinophils from atopic donors had negligible surface expression of FcϵRI-α, which was not enhanced by culture with IgE, IL-3, IL-4, IL-5, GM-CSF, or fibronectin or coculture with fibroblasts. Permeabilization, however, revealed appreciable intracellular staining for FcϵRI-α. The majority of eosinophils were mRNA + for the α, β, and γ subunits of FcϵRI. Small but significant ( P = .03) increases in α chain mRNA expression were observed after coculture of eosinophils with fibroblasts but not with IgE, IL-4, or fibronectin. Cross-linking of FcϵRI on the surface of eosinophils from atopic donors did not lead to detectable EPO release. Conclusion: Human blood eosinophils express negligible, nonfunctional membrane FcϵRI-α but have intracellular FcϵRI-α protein and mRNA expression for the α, β, and γ subunits. (J Allergy Clin Immunol 2000;105:309-17.)

The effects of an anti–IL-13 mAb on cytokine levels and nasal symptoms following nasal allergen challenge

BACKGROUNDnIL-13 is a key T(H)2 cytokine that is implicated in allergic responses.nnnOBJECTIVEnWe evaluated the effects of an anti-IL-13-blocking antibody compared with placebo on repeated nasal allergen challenge responses in hay fever patients out of season.nnnMETHODSnWe performed a parallel group double-blind study of anti-IL-13 (single dose, 6 mg/kg intravenously, nxa0= 16) and placebo (nxa0= 15), with an additional open label group given a topical nasal corticosteroid (nxa0= 5). Subjects received intranasal timothy grass pollen (Phleum pratense P5 allergen), and serial samples of nasal mucosal lining fluid were taken by using synthetic absorptive matrix and by nasal lavage.nnnRESULTSnAdministration of anti-IL-13 on day 1 resulted in a significant decrease in IL-13 levels in synthetic absorptive matrix eluates compared with placebo (area under the curve 0-8 hours, change from baseline) during the late phase after nasal allergen challenge on day 5 (Pxa0< .05) and day 7 (Pxa0< .01). There were no apparent effects of anti-IL-13 treatment on nasal lavage eosinophil numbers or total nasal symptom scores versus placebo. However, in a subgroup with high late-phase IL-13 levels at screening, there was a trend for a decrease in total nasal symptom scores after nasal allergen challenge on day 5, when compared with subjects with low IL-13 levels (Pxa0< .10). Nasal fluticasone caused suppression of IL-13 (Pxa0< .05 on day 5) as well as IL-5 (Pxa0< .01 on day 5) levels in the late phase compared with placebo.nnnCONCLUSIONSnAnti-IL-13 had specific pharmacodynamic action in this nasal allergen challenge model, causing profound inhibition of nasal lining fluid IL-13 responses. In addition, there was a possible effect of anti-IL-13 treatment on total nasal symptom scores in a subgroup with high late-phase nasal IL-13 levels at screening.

Oxidative and Nitrosative Stress and Histone Deacetylase-2 Activity in Exacerbations of COPD

Background Respiratory virus infections are commonly associated with COPD exacerbations, but little is known about the mechanisms linking virus infection to exacerbations. Pathogenic mechanisms in stable COPD include oxidative and nitrosative stress and reduced activity of histone deacetylase-2 (HDAC2), but their roles in COPD exacerbations is unknown. We investigated oxidative and nitrosative stress (O&NS) and HDAC2 in COPD exacerbations using experimental rhinovirus infection. Methods Nine subjects with COPD (Global Initiative for Chronic Obstructive Lung Disease stage II), 10 smokers, and 11 nonsmokers were successfully infected with rhinovirus. Markers of O&NS-associated cellular damage, and inflammatory mediators and proteases were measured in sputum, and HDAC2 activity was measured in sputum and bronchoalveolar macrophages. In an in vitro model, monocyte-derived THP-1 cells were infected with rhinovirus and nitrosylation and activity of HDAC2 was measured. Results Rhinovirus infection induced significant increases in airways inflammation and markers of O&NS in subjects with COPD. O&NS markers correlated with virus load and inflammatory markers. Macrophage HDAC2 activity was reduced during exacerbation and correlated inversely with virus load, inflammatory markers, and nitrosative stress. Sputum macrophage HDAC2 activity pre-infection was inversely associated with sputum virus load and inflammatory markers during exacerbation. Rhinovirus infection of monocytes induced nitrosylation of HDAC2 and reduced HDAC2 activity; inhibition of O&NS inhibited rhinovirus-induced inflammatory cytokines. Conclusions O&NS, airways inflammation, and impaired HDAC2 may be important mechanisms of virus-induced COPD exacerbations. Therapies targeting these mechanisms offer potential new treatments for COPD exacerbations.

Exhaled breath acetone for therapeutic monitoring in pneumonia using selected ion flow tube mass spectrometry (SIFT-MS)

Exhaled breath analysis of volatile organic compounds (VOCs) has great potential in terms of measuring physiological response to treatment. Exhaled breath acetone was measured in patients with community acquired pneumonia for the duration of their in-hospital treatment using Selected Ion Flow Tube-Mass Spectrometry (SIFT-MS). A positive correlation was observed between exhaled breath acetone concentrations and same-day serum C-reactive protein (CRP) levels. Exhaled breath acetone concentrations and CRP levels decreased in the range of 76–90% and 67–80%, respectively, from the day of admission to the day of discharge. This proof of concept study demonstrates the potential of SIFT-MS exhaled breath analysis as a non-invasive tool for clinical therapeutic monitoring.

Pulmonary Infection with Cryptococcus neoformans in the Face of Underlying Sarcoidosis

We present a case of limited pulmonary cryptococcal infection following exposure to pigeon excreta in a patient with sarcoidosis. The pathogenicity of Cryptococcus neoformans depends on the interplay between the immune status of the host and the virulence of the infecting strain. It can range from asymptomatic lung colonization in the immunocompetent host to rapidly progressive meningitis in immunocompromised patients. Immunological models of respiratory disease emphasize a distinction between infections associated with immune suppression on the one hand and diseases such as sarcoidosis believed to involve an excessive Th1-mediated immune response on the other. This case exemplifies the complex nature of immunological responses in the lung and highlights the importance of considering the possibility of co-existent fungal infection in individuals with sarcoidosis. Novel immunotherapeutic options for cryptococcal infection are discussed.

Clinical Features and Outcomes of Patients With Tubercular Uveitis Treated With Antitubercular Therapy in the Collaborative Ocular Tuberculosis Study (COTS)–1

Importance Eradication of systemic tuberculosis (TB) has been limited by neglected populations and the HIV pandemic. Whereas ocular TB often presents as uveitis without any prior evidence of systemic TB, the existing uncertainty in the diagnosis of TB uveitis may perpetuate missed opportunities to address systemic TB. Objective To examine the clinical features of TB uveitis and the associations with response to antitubercular therapy (ATT). Design, Setting, and Participants This retrospective multinational cohort study included patients from 25 ophthalmology referral centers diagnosed with TB uveitis and treated with ATT from January 1, 2004, through December 31, 2014, with a minimum follow-up of 1 year. Main Outcomes and Measures Treatment failure, defined as a persistence or recurrence of inflammation within 6 months of completing ATT, inability to taper oral corticosteroids to less than 10 mg/d or topical corticosteroid drops to less than 2 drops daily, and/or recalcitrant inflammation necessitating corticosteroid-sparing immunosuppressive therapy. Results A total of 801 patients (1272 eyes) were studied (mean [SD] age, 40.5u2009[14.8] years; 413 [51.6%] male and 388 [48.4%] female; 577 [73.6%] Asian). Most patients had no known history (498 of 661 [75.3%]) of systemic TB. Most patients had bilateral involvement (471 of 801 [58.8%]). Common clinical signs reported include vitreous haze (523 of 1153 [45.4%]), retinal vasculitis (374 of 874 [42.8%]), and choroidal involvement (419 of 651 [64.4%]). Treatment failure developed in 102 of the 801 patients (12.7%). On univariate regression analysis, the hazard ratios (HRs) associated with intermediate uveitis (HR, 2.21; 95% CI, 1.07-4.55; Pu2009=u2009.03), anterior uveitis (HR, 2.68; 95% CI, 1.32-2.35; Pu2009=u2009.006), and panuveitis (HR, 3.28; 95% CI, 1.89-5.67; Pu2009<u2009.001) were significantly higher compared with posterior distribution. The presence of vitreous haze had a statistically significant association (HR, 1.95; 95% CI, 1.26-3.02; Pu2009=u2009.003) compared with absence of vitreous haze. Bilaterality had an associated HR of 1.50 (95% CI, 0.96-2.35) compared with unilaterality (HR, 1 [reference]), although this finding was not statistically significant (Pu2009=u2009.07). On multivariate Cox proportional hazards regression analysis, the presence of vitreous haze had an adjusted HR of 2.98 (95% CI, 1.50-5.94; Pu2009=u2009.002), presence of snow banking had an adjusted HR of 3.71 (95% CI, 1.18-11.62; Pu2009=u2009.02), and presence of choroidal involvement had an adjusted HR of 2.88 (95% CI, 1.22-6.78; Pu2009=u2009.02). Conclusions and Relevance A low treatment failure rate occurred in patients with TB uveitis treated with ATT. Phenotypes and test results are studied whereby patients with panuveitis having vitreous and choroidal involvement had a higher risk of treatment failure. These findings are limited by retrospective methods. A prospectively derived composite clinical risk score might address this diagnostic uncertainty through holistic and standardized assessment of the combinations of clinical features and investigation results that may warrant diagnosis of TB uveitis and treatment with ATT.

Tuberculosis or sarcoidosis: Opposite ends of the same disease spectrum?

Tuberculosis and sarcoidosis are chronic systemic diseases that have similar pulmonary and extra-pulmonary manifestations. Multiple studies have found an epidemiological, molecular, and immunological link between the two. It has been suggested that mycobacterium tuberculosis could be a common pathophysiologic mechanism for tuberculosis and sarcoidosis, and that both clinical entities can trigger similar immunological response in patients. Due to this close association, together with possible coexistence in the same patient, the diagnosis of one disease from another may be difficult. In our paper, we suggest that tuberculosis and sarcoidosis are two ends of the same spectrum. Given the pathophysiological and clinical link between the two, we also propose a classification system for tuberculosis and sarcoidosis: Sarcoidosis (S); Sarcoid-Tuberculous (ST); Tuberculous Sarcoid (TS) and Tuberculosis (TB). More research and clinical trials should first be done to affirm the link between the two disease entities.