Lung involvement in monogenic interferonopathies

Filaggrin-Associated Atopic Skin, Eye, Airways, and Gut Disease, Modifying the Presentation of X-Linked Reticular Pigmentary Disorder (XLPDR)

BACKGROUND

X-linked reticular pigmentary disorder (XLPDR) is a rare condition characterized by skin hyperpigmentation, ectodermal features, multiorgan inflammation, and recurrent infections. All probands identified to date share the same intronic hemizygous POLA1 hypomorphic variant (NM_001330360.2(POLA1):c.1393-354A > G) on the X chromosome. Previous studies have supported excessive type 1 interferon (IFN) inflammation and natural killer (NK) cell dysfunction in disease pathogenesis. Common null polymorphisms in filaggrin (FLG) gene underlie ichthyosis vulgaris and atopic predisposition.

CASE

A 9-year-old boy born to non-consanguineous parents developed eczema with reticular skin hyperpigmentation in early infancy. He suffered recurrent chest infections with chronic cough, clubbing, and asthma, moderate allergic rhinoconjunctivitis with keratitis, multiple food allergies, and vomiting with growth failure. Imaging demonstrated bronchiectasis, while gastroscopy identified chronic eosinophilic gastroduodenitis. Interestingly, growth failure and bronchiectasis improved over time without specific treatment.

METHODS

Whole-genome sequencing (WGS) using Illumina short-read sequencing was followed by both manual and orthogonal automated bioinformatic analyses for single-nucleotide variants, small insertions/deletions (indels), and larger copy number variations. NK cell cytotoxic function was assessed using 51Cr release and degranulation assays. The presence of an interferon signature was investigated using a panel of six interferon-stimulated genes (ISGs) by QPCR.

RESULTS

WGS identified a de novo hemizygous intronic variant in POLA1 (NM_001330360.2(POLA1):c.1393-354A > G) giving a diagnosis of XLPDR, as well as a heterozygous nonsense FLG variant (NM_002016.2(FLG):c.441del, NP_0020.1:p.(Arg151Glyfs*43)). Compared to healthy controls, the IFN signature was elevated although the degree moderated over time with the improvement in his chest disease. NK cell functional studies showed normal cytotoxicity and degranulation.

CONCLUSION

This patient had multiple atopic manifestations affecting eye, skin, chest, and gut, complicating the presentation of XLPDR. This highlights that common FLG polymorphisms should always be considered when assessing genotype-phenotype correlations of other genetic variation in patients with atopic symptoms. Additionally, while the patient exhibited an enhanced IFN signature, he does not have an NK cell defect, suggesting this may not be a constant feature of XLPDR.

The world of rare interstitial lung diseases

The world of rare interstitial lung diseases (ILDs) is diverse and complex. Diagnosis and therapy usually pose challenges. This review describes a selection of rare and ultrarare ILDs including pulmonary alveolar proteinosis, pulmonary alveolar microlithiasis and pleuroparenchymal fibroelastosis. In addition, monogenic ILDs or ILDs in congenital syndromes and various multiple cystic lung diseases will be discussed. All these conditions are part of the scope of the European Reference Network on rare respiratory diseases (ERN-LUNG). Epidemiology, pathogenesis, diagnostics and treatment of each disease are presented.

Childhood Interstitial Lung Disease

Childhood interstitial lung disease (chILD) is a heterogeneous group of diseases with various clinical and imaging findings. The incidence and prevalence have increased in recent years, probably due to better comprehension of these rare diseases and increased awareness among physicians. chILDs present with nonspecific pulmonary symptoms, such as tachypnea, hypoxemia, cough, rales, and failure to thrive. Unnecessary invasive procedures can be avoided if specific mutations are detected through genetic examinations or if typical imaging patterns are recognized on computed tomography. Disease knowledge and targeted therapies are improving through international collaboration. Pulmonary involvement in systemic diseases is not uncommon. Pulmonary involvement may be the first finding in connective tissue diseases. This review aims to present a systematic patient-targeted approach to the diagnosis of chILD.

Interstitial lung disease in autoinflammatory disease in childhood: A systematic review of the literature

BACKGROUND/OBJECTIVES

The lung is one of the target organs in the systemic involvement of autoinflammatory disease (AID), and interstitial lung disease (ILD) is the primary phenotype of lung involvement in AID. In this review, we aimed to conduct a systematic review of the available literature to highlight ILD in AID.

METHODS

We conducted a systematic literature search in PubMed/MEDLINE and Scopus from the inception of the databases to January 2022. References were first screened by title and then by abstract by two authors. Eighteen original papers were selected for full-text review.

RESULTS

During the literature search, we identified 18 relevant articles describing 52 cases of AID and ILD. Of those, 44 patients had stimulator of interferon genes-associated vasculopathy with onset in infancy (SAVI), six had coatomer protein complex (COPA) syndrome, one had haploinsufficiency of A20, and one had mevalonate kinase deficiency. Pulmonary fibrosis, cyst formation, and ground glass areas were the most common findings in chest tomography of patients with COPA syndrome and SAVI. Janus kinase inhibitors were used to treat most of the patients with SAVI, which stabilized ILD.

CONCLUSIONS

ILD should be considered carefully in children with AID, especially those with interferonopathy.

Scleroderma specific autoantibodies in rheumatoid arthritis and Sjögren's syndrome patients with interstitial lung disease: Prevalence and associations

Systemic sclerosis (SSc) has been classically linked to interstitial lung disease (ILD) development, often in association with specific SSc autoantibodies. In the present report, we aimed to estimate the prevalence of SSc autoantibodies in 60 seropositive RA and 41 primary SS patients complicated or not by ILD. SSc autoantibodies were determined in patients' sera by a commercial immunoblot assay. RA ILD patients displayed higher frequency of SSc-specific antibodies at strong titers compared to RA-with no lung involvement (25% vs 3.1%, p = 0.01)[OR 95% CI:10.9 (1.2-94.5)], with no differences detected between primary SS groups. These data indicate that many seropositive RA ILD patients probably represent an overlap RA/SSc entity, requiring tailored diagnostic and therapeutic approach.

[When to consider type I interferonopathy in adulthood?]

Type I interferonopathies (IP1) are a heterogeneous group of Mendelian diseases characterized by overactivation of the type I interferon (IFN) pathway. They are caused by monogenic (rarely digenic) mutations of proteins involved in this key pathway of innate immunity. IP1 transmission can be dominant, recessive or X-linked and penetrance differs from one IP1 to another. The clinical spectrum is broad and mainly includes central nervous system involvement with calcifications of the basal ganglia, skin disorders such as cutaneous vasculitis that can be mutilating. Joint disorders including non-destructive deforming arthropathy, pulmonary involvement such as intra-alveolar haemorrhage or interstitial lung disease, and haematological symptoms with cytopenia and/or immune deficiency are also seen. The clinical manifestations vary from one IP1 to another and their spectrum is constantly expanding along with the description of new IP1s and patients. The inflammatory syndrome is generally mild and autoimmune stigmata are frequently found. Almost all patients display overexpression of the type I IFN pathway detected, for instance, by the evaluation of IFN-stimulated genes expression, referred as "interferon signature". The related morbidity and mortality are high. However, the beneficial effect on certain symptoms of targeted therapies inhibiting type I IFN, such as JAK inhibitors, has led to a promising improvement in the management of these patients.