Telomeropathy in Chronic Hypersensitivity Pneumonitis

Polymorphisms and haplotypes of TOLLIP and MUC5B are associated with susceptibility and survival in patients with fibrotic hypersensitivity pneumonitis

INTRODUCTION AND OBJECTIVES

Hypersensitivity pneumonitis (HP) is an interstitial lung disease with diverse clinical features that can present a fibrotic phenotype similar to idiopathic pulmonary fibrosis (IPF) in genetically predisposed individuals. While several single nucleotide polymorphisms (SNPs) have been associated with IPF, the genetic factors contributing to fibrotic HP (fHP) remain poorly understood. This study investigated the association of MUC5B and TOLLIP variants with susceptibility, clinical presentation and survival in Portuguese patients with fHP.

MATERIAL AND METHODS

A case-control study was undertaken with 97 fHP patients and 112 controls. Six SNPs residing in the MUC5B and TOLLIP genes and their haplotypes were analyzed. Associations with risk, survival, and clinical, radiographic, and pathological features of fHP were probed through comparisons among patients and controls.

RESULTS

MUC5B rs35705950 and three neighboring TOLLIP variants (rs3750920, rs111521887, and rs5743894) were associated with increased susceptibility to fHP. Minor allele frequencies were greater among fHP patients than in controls (40.7% vs 12.1%, P<0.0001; 52.6% vs 40.2%, P = 0.011; 22.7% vs 13.4%, P = 0.013; and 23.2% vs 12.9%, P = 0.006, respectively). Haplotypes formed by these variants were also linked to fHP susceptibility. Moreover, carriers of a specific haplotype (G-T-G-C) had a significant decrease in survival (adjusted hazard ratio 6.92, 95% CI 1.73-27.64, P = 0.006). Additional associations were found between TOLLIP rs111521887 and rs5743894 variants and decreased lung function at baseline, and the MUC5B SNP and radiographic features, further highlighting the influence of genetic factors in fHP.

CONCLUSION

These findings suggest that TOLLIP and MUC5B variants and haplotypes may serve as valuable tools for risk assessment and prognosis in fibrotic hypersensitivity pneumonitis, potentially contributing to its patient stratification, and offer insights into the genetic factors influencing the clinical course of the condition.

Genetic Risk Factors in Idiopathic and Non-Idiopathic Interstitial Lung Disease: Similarities and Differences

Recent advances in genetics and epigenetics have provided critical insights into the pathogenesis of both idiopathic and non-idiopathic interstitial lung diseases (ILDs). Mutations in telomere-related genes and surfactant proteins have been linked to familial pulmonary fibrosis, while variants in MUC5B and TOLLIP increase the risk of ILD, including idiopathic pulmonary fibrosis and rheumatoid arthritis-associated ILD. Epigenetic mechanisms, such as DNA methylation, histone modifications, and non-coding RNAs such as miR-21 and miR-29, regulate fibrotic pathways, influencing disease onset and progression. Although no standardized genetic panel for ILD exists, understanding the interplay of genetic mutations and epigenetic alterations could aid in the development of personalized therapeutic approaches. This review highlights the genetic and epigenetic factors driving ILD, emphasizing their potential for refining diagnosis and treatment.

Dyskeratosis congenita with heterozygous RTEL1 mutations presenting with fibrotic hypersensitivity pneumonitis

Dyskeratosis congenita is a rare genetic disorder of telomere insufficiency characterized by a mucocutaneous triad of nail dystrophy, abnormal skin pigmentation, and mucosal leukoplakia. Early diagnosis is important for multidisciplinary approach to its complications including bone marrow failure, malignancy, interstitial lung disease, and liver disease which cause significant morbidity and mortality. We report a genetically confirmed case of dyskeratosis congenita who presented with fibrotic hypersensitivity pneumonitis, highlighting non-mucocutaneous features of dyskeratosis congenita and the need to consider genetic predisposition in a patient with interstitial lung disease and combined unusual manifestations.

Childhood Interstitial Lung Disease: Imaging Guidelines and Recommendations

Childhood interstitial lung disease (ChILD) is an umbrella term encompassing a diverse group of diffuse lung diseases affecting infants and children. Although the timely and accurate diagnosis of ChILD is often challenging, it is optimally achieved through the multidisciplinary integration of imaging findings with clinical data, genetics, and potentially lung biopsy. This article reviews the definition and classification of ChILD; the role of imaging, pathology, and genetics in ChILD diagnosis; treatment options; and future goals. In addition, a practical approach to ChILD imaging based on the latest available research and the characteristic imaging appearance of ChILD entities are presented.

Cellular Senescence in Idiopathic Pulmonary Fibrosis

Cellular senescence (CS) is increasingly implicated in the etiology of age-related diseases. While CS can facilitate physiological processes such as tissue repair and wound healing, senescent cells also contribute to pathophysiological processes involving macromolecular damage and metabolic dysregulation that characterize multiple morbid and prevalent diseases, including Alzheimer's disease, osteoarthritis, atherosclerotic vascular disease, diabetes mellitus, and idiopathic pulmonary fibrosis (IPF). Preclinical studies targeting senescent cells and the senescence-associated secretory phenotype (SASP) with "senotherapeutics" have demonstrated improvement in age-related morbidity associated with these disease states. Despite promising results from these preclinical trials, few human clinical trials have been conducted. A first-in-human, open-label, pilot study of the senolytic combination of dasatinib and quercetin (DQ) in patients with IPF showed improved physical function and mobility. In this review, we will discuss our current understanding of cellular senescence, its role in age-associated diseases, with a specific focus on IPF, and potential for senotherapeutics in the treatment of fibrotic lung diseases.

Mechanisms of progressive fibrosis in connective tissue disease (CTD)-associated interstitial lung diseases (ILDs)

Interstitial lung diseases (ILDs), which can arise from a broad spectrum of distinct aetiologies, can manifest as a pulmonary complication of an underlying autoimmune and connective tissue disease (CTD-ILD), such as rheumatoid arthritis-ILD and systemic sclerosis (SSc-ILD). Patients with clinically distinct ILDs, whether CTD-related or not, can exhibit a pattern of common clinical disease behaviour (declining lung function, worsening respiratory symptoms and higher mortality), attributable to progressive fibrosis in the lungs. In recent years, the tyrosine kinase inhibitor nintedanib has demonstrated efficacy and safety in idiopathic pulmonary fibrosis (IPF), SSc-ILD and a broad range of other fibrosing ILDs with a progressive phenotype, including those associated with CTDs. Data from phase II studies also suggest that pirfenidone, which has a different-yet largely unknown-mechanism of action, may also have activity in other fibrosing ILDs with a progressive phenotype, in addition to its known efficacy in IPF. Collectively, these studies add weight to the hypothesis that, irrespective of the original clinical diagnosis of ILD, a progressive fibrosing phenotype may arise from common, underlying pathophysiological mechanisms of fibrosis involving pathways associated with the targets of nintedanib and, potentially, pirfenidone. However, despite the early proof of concept provided by these clinical studies, very little is known about the mechanistic commonalities and differences between ILDs with a progressive phenotype. In this review, we explore the biological and genetic mechanisms that drive fibrosis, and identify the missing evidence needed to provide the rationale for further studies that use the progressive phenotype as a target population.

Clinical Features of Hypersensitivity Pneumonitis in Children: A Single Center Study

BACKGROUND

Hypersensitivity pneumonia (HP) is an interstitial lung disease (ILD) mainly involving small airways and lung parenchyma that is caused by the inhalation of antigens in susceptible people to stimulate the body's immune response.

METHODS

A total of 6 Chinese children with HP treated in our center from July 2017 to July 2021 were included in our study.

RESULTS

Among the children, there were 4 males and 2 females, ranging in age from 4 to 14 years. Three cases had chest tightness and shortness of breath, 2 cases had cough, 1 case had chest pain, and 1 case had fever. Two cases of children had a history of close contact with pet dogs, 1 case had a history of contact with pigeons, 2 cases lived in a moldy house recently, and 1 case recently played a saxophone that had been idle for more than 2 years. The parents of two cases also had similar symptoms recently. The specific signs of chest HRCT of 6 cases all were in line with the characteristics of HP. After avoiding the sensitization environment, 2 children quickly recovered, 4 patients received low-dose glucocorticoid oral treatment, and after symptom control the dose was gradually reduced. The course of treatment was about 3-6 months.

CONCLUSIONS

Exposure to a potential antigen has been found in all 6 HP children. The clinical manifestations are heterogeneous and easy to confuse with other diseases. A clear history of exposure to the antigens, respiratory symptoms associated with HP, signs of HP on HRCT, and improvement after removal from the antigenic environment constitute the cornerstone of the diagnosis of HP children in our unit. Avoiding exposure to antigenic environment is the first step in treatment, and glucocorticoid use is necessary in children with persistent symptoms.

A Pathophysiological Perspective on COVID-19's Lethal Complication: From Viremia to Hypersensitivity Pneumonitis-like Immune Dysregulation

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the coronavirus responsible for our recent coronavirus disease 2019 pandemic, is driving a lung immunopathology that strongly resembles a severe form of hypersensitivity pneumonitis (HP). A review of recent Severe acute respiratory syndrome-related coronavirus (SARS-CoV) and SARS-CoV-2 medical reports, as well as described characteristics of HP, lead us to postulate a theory for SARS-CoV-2 severe disease. We propose that the novel SARS-CoV-2 can act as a trigger and substrate of an HP-like severe immune reaction especially in genetically vulnerable individuals in addition to those with immune senescence and dysregulation. Accordingly, the purpose of our letter is to shift the emphasis of concern surrounding immune activity from viral infection to an HP-like severe immune reaction. We review similarities in disease presentation between infection and allergy, relevant immunopathology, and outline phases of SARS-CoV-2 disease with perspectives on therapy and critical care. Altogether, the favored course is to begin treatments that address the disease at the earliest phase before immune dysregulation leading to uncontrolled pulmonary inflammation.