[Type I interferonopathies]

French protocol for diagnosis and management of type 1 interferonopathies

Type I interferonopathies are rare genetic diseases characterised by excessive production or signalling of type I interferons (IFN-I), which are key cytokines in the antiviral response. These conditions lead to inappropriate activation of IFN-I pathway, even in the absence of viral stimulation. Over thirty monogenic conditions have been identified, with Aicardi-Goutières syndrome being the most common. The genes involved often relate to the metabolism of intracellular nucleic acids, their detection and signalling pathways, contributing to excessive IFN-I production or signalling. Features usually appear early in life, often within the first year, but diagnosis can also occur in adulthood. It is important to investigate whether there is a family history of consanguinity or vertically transmitted conditions. Key diagnostic features include: (1) Neurological: pseudo-encephalitic phase, psychomotor development retardation or regression, static encephalopathy, spasticity, microcephaly, aseptic lymphocytic meningitis. (2) Radiological: cerebral calcifications, white matter signal abnormalities, cerebral atrophy. (3) Dermatological: chilblains, skin necrosis, skin lesions suggestive of systemic lupus erythematosus (SLE), vasculitis, livedo, panniculitis. (4) Ophthalmological: early-onset glaucoma. (5) Musculoskeletal: myalgia, myositis, joint deformity with calcification, joint subluxation. (6) Pulmonary and renal: interstitial lung disease, pulmonary fibrosis, alveolar haemorrhage, lupus nephritis. (7) Laboratory evidence: lymphopenia, elevated erythrocyte sedimentation rate with normal C-reactive protein, positive antinuclear antibodies. Type I interferonopathies can mimic more common conditions like viral foetopathy or systemic lupus erythematosus. The disease expressivity is variable, even within the same family, making a detailed family history essential. The hallmark of these diseases is increased IFN-I levels in peripheral blood and/or cerebrospinal fluid, a test available only in specialised laboratories. Based on clinical suspicion, patients should be referred to an expert centre. There is no curative treatment to date. Management is multidisciplinary, focusing on symptomatic treatment. In cases of systemic or dermatological involvement, immunosuppressive therapy may be considered, though it increases susceptibility to viral infections. Vaccinations should be updated, with live vaccines contraindicated during immunosuppression unless otherwise specified (Supplemental 2). Monitoring development, supporting disability, and coordinating with social and medical institutions are also crucial aspects of care.

Overlap Diagnostic Odyssey and Full Mouth Rehabilitation of a Juvenile Patient With IFIH1-Related Disorder: A Case of Aicardi-Goutières and Singleton Merten Syndromes Overlap

OBJECTIVE

This case report describes the prosthetic rehabilitation of a 15-year-old female patient with a rare IFIH1-related interferonopathy, presenting features from both Aicardi-Goutières Syndrome (AGS) and Singleton-Merten Syndrome (SMS). The report highlights the unique dental and maxillofacial challenges, and the multidisciplinary treatment approach required in such patients.

METHODS

The patient underwent a comprehensive prosthetic rehabilitation, which included two stages of extractions, followed by the fabrication of a complete upper denture and a two-implant-retained mandibular overdenture. Pre- and post-treatment assessments, including panoramic radiographs and cone beam computed tomography (CBCT), were utilized to guide treatment.

RESULTS

Initial assessments revealed root formation anomalies, multiple impacted teeth, internal resorption, and associated dental anomalies. Following extractions and ridge augmentation, two freestanding implants were successfully placed in the anterior mandible, with no complications during osseointegration. The patient reported satisfaction with the function, esthetics, and stability of her dental prostheses.

CONCLUSIONS

This case underscores the importance of a multidisciplinary approach for managing dental anomalies and bone fragility in patients with IFIH1-related disorders. Early genetic diagnosis and thorough treatment planning are critical for successful prosthetic rehabilitation and optimal patient outcomes.

Advancements in tyrosine kinase-mediated regulation of innate nucleic acid sensing

Innate nucleic acid sensing is a ubiquitous and highly conserved immunological process, which is pivotal for monitoring and responding to pathogenic invasion and cellular damage, and central to host defense, autoimmunity, cell fate determination and tumorigenesis. Tyrosine phosphorylation, a major type of post-translational modification, plays a critical regulatory role in innate immune sensing pathway. Core members of nucleic acid sensing signaling pathway, such as cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS), stimulator of interferon genes (STING), and TANK binding kinase 1 (TBK1), are all subject to activity regulation triggered by tyrosine phosphorylation, thereby affecting the host antiviral defense and anti-tumor immunity under physiological or pathological conditions. This review summarizes the recent advances in research on tyrosine kinases and tyrosine phosphorylation in regulation of nucleic acid sensing. The function and potential applications of targeting tyrosine phosphorylation in anti-tumor immunity is disussed to provide insights for understanding and expanding new anti-tumor strategies.

Ruxolitinib altered IFN-β induced necroptosis of human dental pulp stem cells during osteoblast differentiation

OBJECTIVE

This study aimed to evaluate the role of ruxolitinib in the interferon beta (IFN-β) mediated osteoblast differentiation using human dental pulp stem cells (hDPSCs).

DESIGN

hDPSCs from five deciduous teeth of healthy patients were stimulated by adding human recombinant IFN-β protein (1 or 2 ng/ml) to the osteogenic differentiation induction medium. Substrate formation was determined using Alizarin Red staining, calcium concentration, and osteoblast marker expression levels. Ruxolitinib was used to inhibit the Janus kinase/signal transducers and activators of transcription (JAK-STAT) pathway. Apoptosis was detected using terminal deoxynucleotidyl nick-end labeling (TUNEL) staining, and necroptosis was detected using propidium iodide staining and phosphorylated mixed lineage kinase domain-like protein (pMLKL) expression.

RESULTS

In the IFN-β-treated group, substrate formation was inhibited by a reduction in alkaline phosphatase (ALP) expression in a concentration-dependent manner. Although the proliferation potency was unchanged between the IFN-β-treated and control groups, the cell number was significantly reduced in the experimental group. TUNEL-positive cell number was not significantly different; however, the protein level of necroptosis markers, interleukin-6 (IL-6) and pMLKL were significantly increased in the substrate formation. Cell number and ALP expression level were improved in the group administered ruxolitinib, a JAK-STAT inhibitor. Additionally, ruxolitinib significantly suppressed IL-6 and pMLKL levels.

CONCLUSION

Ruxolitinib interfered with the IFN-β-mediated necroptosis and osteogenic differentiation via the JAK-STAT pathway.

A clinicopathological description of COVID-19-induced chilblains (COVID-toes) correlated with a published literature review

Background

The abundance of publications of COVID‐19‐induced chilblains has resulted in a confusing situation.

Methods

This is a prospective single‐institution study from 15 March to 13 May 2020. Thirty‐two patients received PCR nasopharyngeal swabs. Of these, 28 patients had a thoracic CT‐scan, 31 patients had blood and urine examinations, 24 patients had skin biopsies including immunohistochemical and direct immunofluorescence studies, and four patients had electron microscopy.

Results

COVID‐19‐induced chilblains are clinically and histopathologically identical to chilblains from other causes. Although intravascular thrombi are sometimes observed, no patient had a systemic coagulopathy or severe clinical course. The exhaustive clinical, radiological, and laboratory work‐up in this study ruled‐out other primary and secondary causes. Electron microscopy revealed rare, probable viral particles whose core and spikes measured from 120 to 133 nm within endothelium and eccrine glands in two cases.

Conclusion

This study provides further clinicopathologic evidence of COVID‐19‐related chilblains. Negative PCR and antibody tests do not rule‐out infection. Chilblains represent a good prognosis, occurring later in the disease course. No systemic coagulopathy was identified in any patient. Patients presenting with acral lesions should be isolated, and chilblains should be distinguished from thrombotic lesions (livedo racemosa, retiform purpura, or ischemic acral necrosis).

COVID-19 skin lesions are rarely positive at RT-PCR test: the macrophage activation with vascular impact and SARS-CoV-2-induced cytokine storm

BACKGROUND

Several skin manifestations have been reported since the start of the COVID-19 pandemic: chilblains-like, livedoid lesions, urticaria-like, pseudo-Kawasaki disease, and others. Histopathologic images of these lesions most often show aspects of endothelitis, images similar to autoimmune vasculitis. Cutaneous lesions are often negative at RT-PCR for SARS-CoV-2 virus.

METHOD AND RESULTS

We reviewed recent articles on the mechanisms of COVID-19 and we synthesized main pathways of inflammatory cascade. After the penetration into the cells of the respiratory epithelium, SARS-CoV-2 virus initiates a "cytokine storm" well described in previous publications: the expression of interferon type I (IFN-I) is one of the key elements of the antiviral response in COVID-19 patients, IFN-I expression seems to play an important role in the induction of interleukin 6 (IL-6), chemotactic factors such as Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF) and the consequent activation of monocyte-macrophage system followed by the expression of TNF-alpha, and finally by the induction of coagulation factors by both extrinsic and intrinsic pathways.

CONCLUSIONS

The simplified synthesis of the main pathophysiological mechanisms of COVID-19 could help us to understand at least partially the importance of macrophage activation and its vascular involvement in many skin lesions that remain often negative at in␣situ tests for SARS-CoV-2.

Histologic Patterns and Clues to Autoinflammatory Diseases in Children: What a Cutaneous Biopsy Can Tell Us

Autoinflammation is defined by aberrant, antigen-independent activation of the innate immune signaling pathways. This leads to increased, pro-inflammatory cytokine expression and subsequent inflammation. In contrast, autoimmune and allergic diseases are antigen-directed immune responses from activation of the adaptive immune system. The innate and adaptive immune signaling pathways are closely interconnected. The group of 'complex multigenic diseases' are a result of mutual dysregulation of both the autoinflammatory and autoimmune physiologic components. In contrast, monogenic autoinflammatory syndromes (MAIS) result from single mutations and are exclusively autoinflammatory in their pathogenesis. Studying the clinical and histopathological findings for the various MAIS explains the phenotypical correlates of their specific mutations. This review aims to group the histopathologic clues for autoinflammation into three recognizable patterns. The presence of these histologic patterns in a pediatric patient with recurrent fevers and systemic inflammation should raise suspicion of an autoinflammatory component in MAIS, or, more frequently, in a complex multigenic disease. The three major histopathological patterns seen in autoinflammation are as follows: (i) the 'neutrophilic' pattern, seen in urticarial neutrophilic dermatosis, pustular psoriasis, aseptic neutrophilic folliculitis, and Sweet's syndrome; (ii) the 'vasculitic' pattern seen in small vessel-vasculitis (including hypersensitivity/leukocytoclastic vasculitis, thrombosing microangiopathy and lymphocytic vasculitis), and intermediate-sized vessel vasculitis, mimicking polyarteritis nodosa; and (iii) the 'granulomatous' pattern. Beyond these three patterns, there are additional histopathologic clues, which are detailed below. It is important for a dermatopathologist to recognize the patterns of autoinflammation, so that a diagnosis of MAIS or complex multigenic diseases may be obtained. Finally, careful histopathologic analyses could contribute to a better understanding of the various clinical manifestations of autoinflammation.

A clinical score to guide in decision making for monogenic type I IFNopathies

OBJECTIVE

To develop a set of clinical criteria that identifies patients with a potential autoinflammatory IFNopathy.

METHODS

Based on a literature review, a set of clinical criteria identifying genetically confirmed monogenic IFNopathies was selected. For validation, the clinical score was assessed in healthy controls (HCs) and 18 disease controls, including 2 known autoimmune IFNopathies, juvenile systemic lupus erythematosus (JSLE, n = 4) and dermatomyositis (JDM, n = 4); adenosine deaminase 2 deficiency (DADA2, n = 4); and oligoarticular juvenile idiopathic arthritis (oJIA, n = 6). We assessed an IFN score (IRG-S) in whole blood by NanoString using a previously published 28-gene-IRG-S and a reduced 6-gene-IRG-S.

RESULTS

The 12 patients with a possible IFNopathy had higher clinical scores (3-5) than the patients with sJLE, JDM, DADA2, and oJIA and in HCs. Both the 28-IRG-S and 6-IRG-S were significantly higher in the autoinflammatory IFNopathy patients compared to HCs and oJIA and DADA2 patients but not different from patients with JSLE and JDM. Subsequently, genetic analysis revealed mutations in genes previously reported in genes related to the IFN pathway in 9 of the 12 patients.

CONCLUSION

We developed a clinical score to identify patients with possible autoinflammatory IFNopathies. A clinical score was associated with a high IRG-S and may serve to identify patients with an autoinflammatory IFNopathy.

[Familial chilblain lupus: Four cases spanning three generations]

BACKGROUND

Familial chilblain lupus is a hereditary form of cutaneous lupus erythematosus seen in young children. It shows autosomal dominant inheritance due to mutations in the TREX-1 gene, or, more rarely, SAMHD1 or TMEM173 (STING). It belongs to the type I interferonopathies, i.e. inflammatory diseases associated with excessive interferon production and characterized by a positive "interferon signature". This is a rare entity with fewer than 10 families described to date. We report a new family followed over several years.

PATIENTS AND METHODS

The patients were four subjects from the same family and spanning three generations (a brother and sister aged 17 and 15 years, their 39-year-old mother, and their 60-year-old grandfather). The initial cutaneous lesions on the extremities were described as papular, erythematous, purplish, infiltrated, hyperkeratotic, pruritic and/or painful. They occurred in childhood, improved during summer and stabilized over time. Immunological abnormalities such as positive antinuclear antibodies were noted. The interferon signature was positive in all patients. Molecular analysis of TREX-1, SAMHD1 and STING genes in both children showed no evidence of mutation.

DISCUSSION

The cutaneous involvement was classic except for absence of the scarring and mutilating progression, photosensitivity and vasculopathy reported in other families. There was no intrafamily variability other than unconstant immunological abnormalities. At the molecular level, no mutations in the known genes were identified. A complementary molecular analysis is in progress.

CONCLUSION

We report a new case of familial LEF, thus adding to knowledge about this very rare form of lupus erythematosus.

Molecular and cellular discoveries in inflammatory dermatoses

It was no earlier than 1986 that T helper (Th)1 and Th2 cells were described for the first time, opening the field of lymphocyte diversity and the investigation of the physiopathology of inflammatory diseases such as atopic dermatitis and psoriasis. Since that time, much research has been carried out showing a very complex communication network leading to inflammatory responses. Nowadays, understanding the cellular and molecular components of the inflammatory network and of the different crosstalks not only for groups of diseases but also for the individual patient is mandatory for developing and personalizing treatments. The aim of the present proceeding was to provide an update concerning some of the most recent molecular and cellular discoveries in inflammatory skin diseases and especially of AD.