High background rates of positive tuberculosis-specific interferon-? release assays in a low prevalence region of UK: a surveillance study

Background: Background rates of latent tuberculosis infection in low prevalence regions of Britain are unknown. These would be valuable data for interpreting positive IGRA results, and guiding cost-benefit analyses. The management of a large outbreak of tuberculosis occurring in a rural district hospital provided an opportunity to determine the background rates and epidemiology of IGRA-positivity amongst unselected hospital patients in a low-prevalence region of U.K.Methods: As part of a public health surveillance project we identified 445 individuals exposed to the index cases for clinical assessment and testing by a TB-specific interferon-? release assay (IGRA): T-Spot.TB. Uniquely, an additional comparator group of 191 age-matched individuals without specific recent exposure, but with a similar age distribution and demographic, were recruited from the same wards where exposure had previously occurred, to undergo assessment by questionnaire and IGRA. Results: Rates of IGRA positivity were 8.7% (95%CI, 4.2-13, n=149) amongst unexposed patients, 9.5%(3.0-22, n=21) amongst unexposed staff, 22%(14–29, n=130) amongst exposed patients, 11%(6.1-16, n=142) amongst exposed staff. Amongst the individuals without history of recent exposure to the outbreak, IGRA-positivity was associated with prior TB treatment (OR11, P.04) and corticosteroid use (OR5.9, P.02). Background age-specific prevalences of IGRA-positivity amongst unexposed individuals were: age <40 0%(N/A), age 40–59 15%(12–29), age 60–79 7.0%(1.1-13), age?80 10%(5.9-19).Conclusions: Background rates of IGRA-positivity remain high amongst unselected white-Caucasian hospital inpatients in U.K. These data will aid interpretation of future outbreak studies. As rates peak in the 5th and 6th decade, given an ageing population and increasing iatrogenic immunosuppression, reactivation of LTBI may be a persistent hazard in this population for several decades to come

Reply to Lipworth et al.

We thank Dr. Lipworth and colleagues for their interest in our work published recently in the Journal (1). They rightly point out that the biology of asthma attacks is more complex than blood eosinophils alone and that corticosteroids have a wide range of other potentially relevant antiinflammatory effects. However, local treatment with inhaled corticosteroids (ICS) is usually the mainstay of patients with frequent eosinophilic exacerbations, and therefore in the great majority of patients, the key question is what oral corticosteroids (OCS) add to ICS in an acute attack (2) and whether this effect is seen with benralizumab. We suggest that depletion of circulating eosinophils is the only effect OCS are likely to have that are not shared with ICS (3)

Multidimensional endotyping in patients with severe asthma reveals inflammatory heterogeneity in matrix metalloproteinases and chitinase 3–like protein 1

BackgroundDisease heterogeneity in patients with severe asthma and its relationship to inflammatory mechanisms remain poorly understood.ObjectiveWe aimed to identify and replicate clinicopathologic endotypes based on analysis of blood and sputum parameters in asthmatic patients.MethodsOne hundred ninety-four asthmatic patients and 21 control subjects recruited from 2 separate centers underwent detailed clinical assessment, sputum induction, and phlebotomy. One hundred three clinical, physiologic, and inflammatory parameters were analyzed by using topological data analysis and Bayesian network analysis.ResultsSevere asthma was associated with anxiety and depression, obesity, sinonasal symptoms, decreased quality of life, and inflammatory changes, including increased sputum chitinase 3–like protein 1 (YKL-40) and matrix metalloproteinase (MMP) 1, 3, 8, and 12 levels. Topological data analysis identified 6 clinicopathobiologic clusters replicated in both geographic cohorts: young, mild paucigranulocytic; older, sinonasal disease; obese, high MMP levels; steroid resistant TH2 mediated, eosinophilic; mixed granulocytic with severe obstruction; and neutrophilic, low periostin levels, severe obstruction. Sputum IL-5 levels were increased in patients with severe particularly eosinophilic forms, whereas IL-13 was suppressed and IL-17 levels did not differ between clusters. Bayesian network analysis separated clinical features from intricately connected inflammatory pathways. YKL-40 levels strongly correlated with neutrophilic asthma and levels of myeloperoxidase, IL-8, IL-6, and IL-6 soluble receptor. MMP1, MMP3, MMP8, and MMP12 levels were associated with severe asthma and were correlated positively with sputum IL-5 levels but negatively with IL-13 levels.ConclusionIn 2 distinct cohorts we have identified and replicated 6 clinicopathobiologic clusters based on blood and induced sputum measures. Our data underline a disconnect between clinical features and underlying inflammation, suggest IL-5 production is relatively steroid insensitive, and highlight the expression of YKL-40 in patients with neutrophilic inflammation and the expression of MMPs in patients with severe asthma

Hypoxic and pharmacological activation of HIF inhibits SARS-CoV-2 infection of lung epithelial cells

COVID-19, caused by the novel coronavirus SARS-CoV-2, is a global health issue with more than 2 million fatalities to date. Viral replication is shaped by the cellular microenvironment, and one important factor to consider is oxygen tension, in which hypoxia inducible factor (HIF) regulates transcriptional responses to hypoxia. SARS-CoV-2 primarily infects cells of the respiratory tract, entering via its spike glycoprotein binding to angiotensin-converting enzyme 2 (ACE2). We demonstrate that hypoxia and the HIF prolyl hydroxylase inhibitor Roxadustat reduce ACE2 expression and inhibit SARS-CoV-2 entry and replication in lung epithelial cells via an HIF-1α-dependent pathway. Hypoxia and Roxadustat inhibit SARS-CoV-2 RNA replication, showing that post-entry steps in the viral life cycle are oxygen sensitive. This study highlights the importance of HIF signaling in regulating multiple aspects of SARS-CoV-2 infection and raises the potential use of HIF prolyl hydroxylase inhibitors in the prevention or treatment of COVID-19

Epithelial IL-6 trans-signaling defines a new asthma phenotype with increased airway inflammation

Background: Although several studies link high levels of IL-6 and soluble IL-6 receptor (sIL-6R) to asthma severity and decreased lung function, the role of IL-6 trans-signaling (IL-6TS) in asthmatic patients is unclear. Objective: We sought to explore the association between epithelial IL-6TS pathway activation and molecular and clinical phenotypes in asthmatic patients. Methods: An IL-6TS gene signature obtained from air-liquid interface cultures of human bronchial epithelial cells stimulated with IL-6 and sIL-6R was used to stratify lung epithelial transcriptomic data (Unbiased Biomarkers in Prediction of Respiratory Disease Outcomes [U-BIOPRED] cohorts) by means of hierarchical clustering. IL-6TS-specific protein markers were used to stratify sputum biomarker data (Wessex cohort). Molecular phenotyping was based on transcriptional profiling of epithelial brushings, pathway analysis, and immunohistochemical analysis of bronchial biopsy specimens. Results: Activation of IL-6TS in air-liquid interface cultures reduced epithelial integrity and induced a specific gene signature enriched in genes associated with airway remodeling. The IL-6TS signature identified a subset of patients with IL-6TS-high asthma with increased epithelial expression of IL-6TS-inducible genes in the absence of systemic inflammation. The IL-6TS-high subset had an overrepresentation of frequent exacerbators, blood eosinophilia, and submucosal infiltration of T cells and macrophages. In bronchial brushings Toll-like receptor pathway genes were upregulated, whereas expression of cell junction genes was reduced. Sputum sIL-6R and IL-6 levels correlated with sputum markers of remodeling and innate immune activation, in particular YKL-40, matrix metalloproteinase 3, macrophage inflammatory protein 1 beta, IL-8, and IL-1 beta. Conclusions: Local lung epithelial IL-6TS activation in the absence of type 2 airway inflammation defines a novel subset of asthmatic patients and might drive airway inflammation and epithelial dysfunction in these patients.Peer reviewe

Epithelial IL-6 trans-signaling defines a new asthma phenotype with increased airway inflammation

Background: Although several studies link high levels of IL-6 and soluble IL-6 receptor (sIL-6R) with asthma severity and decreased lung function, the role of IL-6 trans-signaling (IL-6TS) in asthma is unclear. Objective: To explore the association between epithelial IL-6TS pathway activation and molecular and clinical phenotypes in asthma. Methods: An IL-6TS gene signature, obtained from air-liquid interface (ALI) cultures of human bronchial epithelial cells stimulated with IL-6 and sIL-6R, was used to stratify lung epithelium transcriptomic data (U-BIOPRED cohorts) by hierarchical clustering. IL-6TS-specific protein markers were used to stratify sputum biomarker data (Wessex cohort). Molecular phenotyping was based on transcriptional profiling of epithelial brushings, pathway analysis and immunohistochemical analysis of bronchial biopsies. Results: Activation of IL-6TS in ALI cultures reduced epithelial integrity and induced a specific gene signature enriched in genes associated with airway remodeling. The IL-6TS signature identified a subset of IL-6TS. High asthma patients with increased epithelial expression of IL-6TS inducible genes in absence of systemic inflammation. The IL-6TS High subset had an overrepresentation of frequent exacerbators, blood eosinophilia, and submucosal infiltration of T cells and macrophages. In bronchial brushings, TLR pathway genes were up-regulated while the expression of tight junction genes was reduced. Sputum sIL-6R and IL-6 levels correlated with sputum markers of remodeling and innate immune activation, in particular YKL-40, MMP3, MIP-1β, IL-8 and IL-1β. Conclusions: Local lung epithelial IL-6TS activation in absence of type 2 airway inflammation defines a novel subset of asthmatics and may drive airway inflammation and epithelial dysfunction in these patients

MAIT cells in autoimmunity, immune mediated diseases and airways disease

Mucosal associated invariant T (MAIT) cells are a novel class of innate-like T cells, expressing a semi-invariant T cell receptor and able to recognize small molecules presented on the non-polymorphic MHC-related protein 1. Their intrinsic effector-memory phenotype, enabling secretion of pro-inflammatory cytokines, and their relative abundance in humans implies a significant potential to contribute to autoimmune processes. However, as MAIT cells were unknown until recently and specific immunological tools were unavailable, to date little is known of their roles in disease. Here I review observations from clinical studies and animal models of autoimmune and immune mediated diseases including the roles of MAIT cells in systemic lupus erythematosus, rheumatoid arthritis, multiple sclerosis, inflammatory bowel disease and airways diseases. MAIT cell deficiencies are frequently observed in peripheral blood, and at sites of disease such as the airways in asthma. However MAIT cells have a specific sensitivity to suppression by therapeutic corticosteroids that may confound many of these observations, as may the tendency of the surface marker CD161 to activation-induced down-regulation. Nonetheless the dependence on bacteria for the development of MAIT cells suggests a potentially important protective role linking the influences of early life microbial exposures and subsequent development of autoimmunity. Conversely MAIT cells could contribute to chronic inflammation either through TCR-independent activation, or potentially by TCR recognition of as-yet undiscovered ligands. Future research will be greatly facilitated by the immunological tools now available, including murine genetic models and human and murine specific tetramers

Treatment options in type-2 low asthma

Monoclonal antibodies targeting IgE or the type-2 cytokines interleukin (IL)-4, IL-5 and IL-13 are proving highly effective in reducing exacerbations and symptoms in people with severe allergic and eosinophilic asthma, respectively. However, these therapies are not appropriate for 30-50% of patients in severe asthma clinics who present with non-allergic, non-eosinophilic, "type-2 low" asthma. These patients constitute an important and common clinical asthma phenotype, driven by distinct, yet poorly understood pathobiological mechanisms. In this review we describe the heterogeneity and clinical characteristics of type-2 low asthma and summarise current knowledge on the underlying pathobiological mechanisms, which includes neutrophilic airway inflammation often associated with smoking, obesity and occupational exposures and may be driven by persistent bacterial infections and by activation of a recently described IL-6 pathway. We review the evidence base underlying existing treatment options for specific treatable traits that can be identified and addressed. We focus particularly on severe asthma as opposed to difficult-to-treat asthma, on emerging data on the identification of airway bacterial infection, on the increasing evidence base for the use of long-term low-dose macrolides, a critical appraisal of bronchial thermoplasty, and evidence for the use of biologics in type-2 low disease. Finally, we review ongoing research into other pathways including tumour necrosis factor, IL-17, resolvins, apolipoproteins, type I interfemns, IL-6 and mast cells. We suggest that type-2 low disease frequently presents opportunities for identification and treatment of tractable clinical problems; it is currently a rapidly evolving field with potential for the development of novel targeted therapeutics

Mycobacterium tuberculosis-specific cellular immune profiles suggest bacillary persistence decades after spontaneous cure in untreated tuberculosis

Individuals with self-healed tuberculosis from the preantibiotic era offer a unique insight into the natural history of and protective immunity to tuberculosis. In 27 such persons whose tuberculosis self-healed >50 years earlier, circulating Mycobacterium tuberculosis antigen-specific interferon ? (IFN-?)- and interleukin 2 (IL-2)-secreting T cells were detected ex vivo in 16 and 19 individuals, respectively. The M. tuberculosis-specific T cell cytokine profile was dominated by effector memory T cells that secrete both IFN-? and IL-2 and included T cells that secrete only IFN-? or IL-2, suggesting persistence of antigen secreted by viable bacilli. Of 10 individuals with no M. tuberculosis antigen-specific IFN-?-secreting T cells detectable ex vivo, 7 had evidence of central memory T cells, consistent with clearance of infection