Druggable monogenic immune defects hidden in diverse medical specialties: Focus on overlap syndromes

In the last two decades two new paradigms changed our way of perceiving primary immunodeficiencies: An increasing number of immune defects are more associated with inflammatory or autoimmune features rather than with infections. Some primary immune defects are due to hyperactive pathways that can be targeted by specific inhibitors, providing innovative precision treatments that can change the natural history of diseases. In this article we review some of these “druggable” inborn errors of immunity and describe how they can be suspected and diagnosed in diverse pediatric and adult medicine specialties. Since the availability of precision treatments can dramatically impact the course of these diseases, preventing the development of organ damage, it is crucial to widen the awareness of these conditions and to provide practical hints for a prompt detection and cure.

Coincident Kikuchi-Fujimoto's disease and adult-onset Still's disease: report of a patient from an uncommonly affected population and case-directed systematic review

Kikuchi-Fujimoto's disease (KFD) and adult-onset Still's disease (AOSD) are rare idiopathic inflammatory conditions of unknown etiology. Ten prior instances of KFD and AOSD occurring together have been reported in the medical literature. These overlaps, together with certain distinguishing clinical and laboratory characteristics in these co-occurrences, offer insight into the pathophysiology of both of these rare disorders. Too, examination of these cases may help improve the diagnostic evaluation and care of patients afflicted with these rare diseases. We therefore report an additional patient with KFD and AOSD occurring in a middle-aged Hispanic female patient and perform a systematic literature review using the PubMed/MEDLINE and Embase databases to further analyze and compare prior identified cases. Our observations in our index case complement and expand previous reports, including new demographic and diagnostic features not seen in prior cases of overlap. Indeed ours is the first in a patient of Hispanic ethnicity, with retroperitoneal lymphadenopathy, as well as with a skin biopsy consistent with AOSD. Each of the reviewed cases of co-occurrence met the diagnostic criteria for both KFD and AOSD. This finding, in the setting of unique clinical and diagnostic manifestations that are not typically seen in either disease entity alone, suggests the presence of an overlap syndrome. Also, many of the shared clinical features and symptomatic responses to targeted therapies implies a similar, yet still poorly understood, pathophysiologic pathway for the two diseases.

Myelodysplastic syndromes and overlap syndromes

Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematological neoplasms characterized by ineffective hematopoiesis, morphologic dysplasia, and cytopenia. MDS overlap syndromes include various disorders, such as myelodysplastic/myeloproliferative neoplasms and hypoplastic MDS with aplastic anemia characteristics. MDS overlap syndromes share the characteristics of other diseases, which make differential diagnoses challenging. Advances in genomic studies have led to the discovery of frequent mutations in MDS and overlap syndromes; however, most of the mutations are not specific for the diagnosis of these diseases. The molecular characteristics of the overlap syndromes usually do not show a just “in-between” form but rather heterogeneous features. Established diagnostic criteria for these diseases based on clinical, morphologic, and laboratory features are still useful when combined with genomic data. It is expected that further studies for MDS and overlap syndromes will place emphasis on the roles of mutations as therapeutic targets and prognostic indicators.

The clinicoserological spectrum of inflammatory myopathy in the context of systemic sclerosis and systemic lupus erythematosus

The autoimmune rheumatic diseases (ARDs) are characterised by a pathological triad composed of autoimmunity/inflammation, microangiopathy and aberrant tissue remodelling. Disease terms such as idiopathic inflammatory myopathy (IIM), scleroderma/systemic sclerosis (SSc), and systemic lupus erythematosus (SLE) are helpful clinically but disguise the considerable overlap that exists within these 'distinct' disorders. This is perhaps best demonstrated by inflammatory myopathy, which can be present in SSc or SLE, but can itself be absent in clinically amyopathic IIM. Archetypal clinical manifestations of ARD (such as Raynaud's phenomenon) are frequently present, albeit with varying prominence, within each of these diseases. This is certainly the case for inflammatory myositis, which has long been recognised as an important clinical feature of both SSc and SLE. Progress in elucidating the clinicoserological spectrum of autoimmune rheumatic diseases has identified autoantibody specificities that are strongly associated with 'overlap' disease and the presence of inflammatory myositis in SSc and SLE. In this review, we shall describe the prevalence, burden, prognostic value and management considerations of IIM in the context of both SSc and SLE. A major emphasis on the value of autoantibodies shall highlight the value of these tools in predicting the future occurrence of inflammatory myositis in both SSc and SLE. Where applicable, unmet research needs shall be highlighted. The review emphasises the importance of myopathy as a common feature across all the ARDs, and highlights specific antibody specificities that are strongly associated with myopathy in the context of SLE and SSc.

Anti-phospholipid syndrome leading to digital ischaemia and rare organ complications in systemic sclerosis and related disorders

Antiphospholipid syndrome (APS) is an acquired, autoimmune thrombophilia that can occur as a primary disorder (with no associated disease) or secondary to infection, medication usage and autoimmune rheumatic diseases (ARDs). The association between APS and systemic lupus erythematosus (SLE) is well established, and practicing rheumatologists check for APS antibodies in the routine assessment of SLE, particularly if clinical features such as thrombotic events or pregnancy loss are present. APS secondary to systemic sclerosis (SSc)-related disorders is less widely recognised and easily overlooked. We describe 5 cases that highlight the varied breadth of clinical manifestations of APS in the context of SSc and related disorders. These cases range from uncomplicated Raynaud's phenomenon, digital ulceration/necrosis, critical digital ischaemia/gangrene and rare internal organ complications of APS in SSc-spectrum disorders. To our knowledge, our cases include the first reported case of secondary APS contributing to digital necrosis in the context of RACAND syndrome (Raynaud's phenomenon, anti-centromere antibodies and necrosis of the digits) and the first reported case of secondary APS in SSc causing posterior reversible encephalopathy syndrome (PRES). The case series is accompanied by a comprehensive review of the literature relevant to each case. Rheumatologists should be alert to the possibility of APS in SSc-spectrum disorders and should routinely check APS antibodies in all patients at diagnosis, and again later in the disease course if new features emerge that could indicate the presence of thrombotic events or other recognised APS manifestations. Key points • APS should be considered in all patients with digital ischaemic symptoms. • APS may be an important driver of SSc-related digital ulceration/necrosis. • Identification of SSc-associated APS opens up new therapeutic options for acute management and secondary prevention.

Treatment of MDS/MPN and the MDS/MPN IWG International Trial: ABNL MARRO

PURPOSE OF REVIEW

MDS/MPNs comprise a group of rare hematologic malignancies that balance features of myeloproliferation and bone marrow failure. Given overlapping clinical features and rarity of incidence, MDS/MPNs have long posed a diagnostic and therapeutic challenge. Herein, we sought to review recent advances in diagnosis and emerging therapeutic strategies and highlight the upcoming ABNL MARRO study which aims to individualize therapy for patients with MDS/MPN.

RECENT FINDINGS

Focused study of molecular mutations in MDS/MPNs has provided improved diagnostic clarity. Specific gene mutation or patterns of mutation have been increasingly described and have helped to distinguish between clinically similar diseases. While the current treatment landscape consists largely of therapies that have been co-opted from related disease, the emergence of prospective clinical trials specifically focused on MDS/MPN and the increased use of targeted agents represent progress for patients with MDS/MPN. An improved understanding of the molecular drivers of myeloid diseases has provided diagnostic clarity and renewed hope of targeted therapies for MDS/MPN patients. The upcoming ABNL MARRO study hopes to leverage this knowledge to match patients with targeted therapeutic options specific to molecular drivers of their disease.

Prevalence of overlap of antineutrophil cytoplasmic antibody associated vasculitis with systemic autoimmune diseases: an unrecognized example of poliautoimmunity

We aimed to estimate the frequency of overlap of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) with systemic autoimmune diseases. Retrospective single-center study to identify patients with AAV diagnosis and concomitant autoimmune systemic diseases, simultaneously, before or after the diagnosis of AAV. Sociodemographic characteristics, such as comorbidities; follow-up time; type of AAV; disease duration; relapses; treatment and response; clinical, serological, and histological characteristics; disease activity and damage; prognosis; dialysis requirements, and death were assessed. Twenty-eight of two hundred and forty-seven patients (11.3%) with AAV had a concomitant diagnosis of autoimmune disease. The predominant AAV type was renal-limited vasculitis (39%), followed by granulomatosis with polyangiitis (29%), mycroscopic polyangiitis (25%), and eosinophilic granulomatosis with polyangiitis (7%). Mean age at AAV diagnosis was 50 ± 17 years and 24/28 were ANCA positive. The main clinical manifestations were renal (79%), otorhinolaryngologic (43%), and pulmonary and peripheral neuropathy (32%). Sixteen patients (57%) experienced partial or total remission at a median follow-up of 34 months, and four patients (14%) died. The most frequent autoimmune disease overlapped was rheumatoid arthritis (39%), followed by Sjögren's syndrome and systemic sclerosis (14%), mixed connective tissue disease (11%), systemic lupus erythematosus and juvenile idiopathic arthritis (7%), and ankylosing spondylitis and IgG4-related disease (4%). In nine patients (32%), both diagnoses were simultaneous; in the rest, median time elapsed between the autoimmune disease and AAV diagnosis was 173 months. The prevalence of overlap AAV with other autoimmune diseases was low. The most common AAV phenotype was renal-limited vasculitis, and the most frequent overlap disease was rheumatoid arthritis.

Cardiac Arrhythmias Related to Sodium Channel Dysfunction

The voltage-gated cardiac sodium channel (Na_v1.5) is a mega-complex comprised of a pore-forming α subunit and 4 ancillary β-subunits together with numerous protein partners. Genetic defects in the form of rare variants in one or more sodium channel-related genes can cause a loss- or gain-of-function of sodium channel current (I_Na) leading to the manifestation of various disease phenotypes, including Brugada syndrome, long QT syndrome, progressive cardiac conduction disease, sick sinus syndrome, multifocal ectopic Purkinje-related premature contractions, and atrial fibrillation. Some sodium channelopathies have also been shown to be responsible for sudden infant death syndrome (SIDS). Although these genetic defects often present as pure electrical diseases, recent studies point to a contribution of structural abnormalities to the electrocardiographic and arrhythmic manifestation in some cases, such as dilated cardiomyopathy. The same rare variants in SCN5A or related genes may present with different clinical phenotypes in different individuals and sometimes in members of the same family. Genetic background and epigenetic and environmental factors contribute to the expression of these overlap syndromes. Our goal in this chapter is to review and discuss what is known about the clinical phenotype and genotype of each cardiac sodium channelopathy, and to briefly discuss the underlying mechanisms.

The Challenge of Treating Myelodysplastic Syndromes/Myeloproliferative Neoplasms

Myelodysplastic syndromes/myeloproliferative neoplasms (MDS/MPN) comprise a spectrum of myeloid disorders with both dysplastic and proliferative features, arising from hematopoietic stem cells. MDS/MPN are neither MDS nor MPN but a distinct World Health Organization-defined subclassification of diseases that, by definition, do not arise from a pre-existing MDS or MPN, inherently creating diagnostic and therapeutic challenges. Appropriately recognizing and classifying MDS/MPN is paramount for appropriately formulating treatment strategies and accurate prognostication. Highlighting the unique molecular, morphologic, and clinical characteristics among the subclassifications of MDS/MPN can assist in the appropriate diagnosis and aid in choice of therapeutic strategies. We describe the challenges of the appropriate diagnosis and treatment of MDS/MPN.

Diagnosis and treatment of trigeminy overlap syndrome of autoimmune liver disease

AIM: To investigate the diagnosis and treatment of trigeminy overlap syndrome [autoimmune hepatitis-primary biliary cirrhosis-primary sclerosing cholangitis overlap syndrome (AIH-PBC-PSC OS)] of autoimmune liver disease (AILD).

METHODS: All data for seven patients diagnosed with AIH-PBC-PSC OS by liver biopsy, including clinical characteristics and biochemistry indexes, autoantibodies, imaging findings and liver histology, were analyzed. Ursodeoxycholic acid (UDCA) [13-15 mg/(kg•d)], prednisone (30 mg/d, diminished by 5 mg/qw, until 10 mg/d) and azathioprine (AZA) (50 mg/d) were given to these patients.

RESULTS: Over 12 mo of observation, the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), γ-glutamyl transpeptidase (GGT), and alkaline phosphatase (ALP) in all the 7 patients decreased, and the levels of TBIL increased. Compared with baseline value, there was a significant decrease in ALP (P < 0.05). However, there were no significant differences in other parameters (P > 0.05). Pathological results showed the characteristics of AIH, PBC and PSC. Liver transplantation was performed in one patient, and the hepatic function of the patient was normal after operation. Four patients died (one died of hepatic failure and one died of gastrointestinal bleeding) during follow-up.

CONCLUSION: The diagnosis of AILD is based mainly on serologic tests and characteristic histological features. The short-term mortality of AIH-PBC-PSC OS is high. The effect of medical treatment for patients with AIH-PBC-PSC OS is poor. Liver transplantation is the only option with known therapeutic benefit for end-stage patients.

Clinical Presentation and Outcomes of Autoimmune Hepatitis in Inflammatory Bowel Disease

Nearly one-third of patients with inflammatory bowel disease (IBD) have abnormal liver tests, which can be indicative of underlying hepatic disease. Primary sclerosing cholangitis has a clear association with ulcerative colitis, but other autoimmune disorders such as autoimmune hepatitis (AIH) have also been associated with IBD. AIH may also occur in the setting of an overlap syndrome or in the setting of medications, particularly tumor necrosis factor alpha inhibitors. Importantly, some studies have shown that IBD patients with AIH fail treatment more frequently than IBD patients without AIH. This review will focus on the clinical characteristics, diagnosis, and management of autoimmune hepatitis in inflammatory bowel disease patients.

Association of ANCA associated vasculitis and rheumatoid arthritis: a lesser recognized overlap syndrome

BACKGROUND

ANCA associated vasculitis (AAV) is an autoimmune disease with significant morbidity and mortality, in which diagnostic delay is associated with worse outcomes. AAV is rarely found in association with other immune mediated diseases. Early recognition of such overlaps enables more timely diagnosis and may impact on disease outcome. We reviewed cases of AAV in which there was an overlap with rheumatoid arthritis (RA).

METHODS

We performed a retrospective analysis of our vasculitis database for patients who had a diagnosis of AAV and RA, and a literature search to find other reported cases of this overlap syndrome.

RESULTS

We found six subjects who had a diagnosis of RA and developed AAV at a median of 10.5 years (range 4-43 years) after the diagnosis of RA. They had been treated with a mean of 2 disease modifying drugs (0-4) and all had evidence of renal involvement with median creatinine of 227 μmol/l (range 128-700 μmol/l). Only one had a diagnosis of granulomatosis with polyangiitis, while the rest had a clinical diagnosis of microscopic polyangiitis. Half of the patients had positive rheumatoid factor (RhF) at the time of vasculitis diagnosis, three had MPO-ANCA, one PR3-ANCA, and two had ANCA-negative pauci-immune vasculitis. Additionally, we found 29 other cases reported of this overlap, which also most frequently presented with vasculitic renal manifestations, and were frequently RhF positive at the time of AAV diagnosis.

CONCLUSIONS

AAV occurs in subjects with RA rarely, and often with significant delay from the first rheumatological manifestations. Renal involvement is common.

Autoimmune hepatitis, one disease with many faces: Etiopathogenetic, clinico-laboratory and histological characteristics

Autoimmune hepatitis (AIH) is an unresolving progressive liver disease of unknown etiology characterized by hypergammaglobulinemia, autoantibodies detection and interface hepatitis. Due to the absence of specific diagnostic markers and the large heterogeneity of its clinical, laboratory and histological features, AIH diagnosis may be potentially difficult. Therefore, in this in-depth review we summarize the substantial progress on etiopathogenesis, clinical, serological and histological phenotypes of AIH. AIH has a global distribution affecting any age, both sexes and all ethnic groups. Clinical manifestations vary from asymptomatic to severe or rarely fulminant hepatitis. Hypergammaglobulinemia with selective elevation of IgG is found in most cases. Autoimmune attack is perpetuated, possibly via molecular mimicry, and favored by the impaired control of T-regulatory cells. Histology (interface hepatitis, emperipolesis and hepatic rosette formation) and autoantibodies detection although not pathognomonic, are still the hallmark for a timely diagnosis. AIH remains a major diagnostic challenge. AIH should be considered in every case in the absence of viral, metabolic, genetic and toxic etiology of chronic or acute hepatitis. Laboratory personnel, hepato-pathologists and clinicians need to become more familiar with disease expressions and the interpretation of liver histology and autoimmune serology to derive maximum benefit for the patient.

Facing the Challenge of Acute Autoimmune Liver Disease: Report of a Case and Review of the Literature

Autoimmune liver diseases (ALD) comprise two broad categories: those with a hepatic predominance, autoimmune hepatitis (AIH), and those with a predominance of cholestatic features including primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). An overlap syndrome (OS) is thought to exist where a patient appears with clinical features of more than one immune-mediated liver disease. Based on one personal observation we report a case of histologically proven OS. The relevant literature is briefly reviewed. A 68-year-old male was admitted in our department with general malaise, anorexia and jaundice. Trans-abdominal ultrasonography as well as computerized tomography showed a slightly enlarged liver with mild fatty deposition and the patient was submitted to transcutaneous liver biopsy. Histological features included inflammatory infiltration of intra-hepatic bile ducts with the presence of endoepithelial lymphocytes and plasma cells, degenerative distortions and even focal damage of relevant epithelial cellular structures, periductal fibrosis, portal inflammation, interface hepatitis, ductular proliferation and canalicular cholestasis. It is apparent that exact definitions pertaining the OS are limited and general consensus on the precise determinations of overlap/variant syndromes is warranted in order to enable more accurate future research and establish common guidelines in the management of the condition.

Update on autoimmune hepatitis

Autoimmune hepatitis (AIH) is a necroinflammatory liver disease of unknown etiology that occurs in children and adults of all ages. Characteristics are its autoimmune features, hyperglobulinemia (IgG), and the presence of circulating autoantibodies, as well as a response to immunosuppressant drugs. Current treatment consists of prednisone and azathioprine and in most patients this disease has become very treatable. Over the past 2 years, a couple of new insights into the genetic aspects, clinical course and treatment of AIH have been reported, which will be the focus of this review. In particular, we concentrate on genome-wide microsatellite analysis, a novel mouse model of AIH, the evaluation of a large AIH cohort for overlap syndromes, suggested novel criteria for the diagnosis of AIH, and the latest studies on treatment of AIH with budenoside and mycophenolate mofetil.