Katherine Pak

Human endogenous retrovirus-K contributes to motor neuron disease

Human endogenous retrovirus-K is activated in the cortical neurons of patients with amyotrophic lateral sclerosis, and expression of the viral envelope protein in mouse brain reproduces the clinical and pathological phenotype of this disease. A viral endgame A large number of viral sequences are present in the human genome but remain silent. However, under pathological conditions, these viruses can get expressed. Li et al. now report that one such virus, human endogenous retrovirus-K, is expressed in neurons of a subpopulation of patients with amyotrophic lateral sclerosis (ALS), a progressive neurodegenerative disease. The envelope protein of this virus causes degeneration of neurons, and transgenic animals expressing this protein develop an ALS-like syndrome caused by nucleolar dysfunction in motor neurons. Reactivation of the virus is regulated by the transcription factor TDP-43. Thus, therapeutic approaches against this virus could potentially alter the course of the disease. The role of human endogenous retroviruses (HERVs) in disease pathogenesis is unclear. We show that HERV-K is activated in a subpopulation of patients with sporadic amyotrophic lateral sclerosis (ALS) and that its envelope (env) protein may contribute to neurodegeneration. The virus was expressed in cortical and spinal neurons of ALS patients, but not in neurons from control healthy individuals. Expression of HERV-K or its env protein in human neurons caused retraction and beading of neurites. Transgenic animals expressing the env gene developed progressive motor dysfunction accompanied by selective loss of volume of the motor cortex, decreased synaptic activity in pyramidal neurons, dendritic spine abnormalities, nucleolar dysfunction, and DNA damage. Injury to anterior horn cells in the spinal cord was manifested by muscle atrophy and pathological changes consistent with nerve fiber denervation and reinnervation. Expression of HERV-K was regulated by TAR (trans-activation responsive) DNA binding protein 43, which binds to the long terminal repeat region of the virus. Thus, HERV-K expression within neurons of patients with ALS may contribute to neurodegeneration and disease pathogenesis.

Cytosolic 5'-Nucleotidase 1A As a Target of Circulating Autoantibodies in Autoimmune Diseases.

Prior investigations demonstrated that autoantibodies recognizing cytosolic 5′‐nucleotidase 1A (NT5C1A) are found in 33–76% of patients with inclusion body myositis (IBM) but are observed only rarely in patients with polymyositis (PM). Thus, anti‐NT5C1A may help distinguish IBM from PM. Although 4–21% of patients with dermatomyositis (DM) were shown to be anti‐NT5C1A antibody positive, the clinical features of anti‐NT5C1A–positive patients with DM have not been described. Furthermore, the prevalence of anti‐NT5C1A antibodies in other rheumatic conditions has not been reported. This study was undertaken to define the prevalence and clinical features of anti‐NT5C1A–positive patients with DM, PM, IBM, or other systemic autoimmune diseases.

Cytosolic 5'‐nucleotidase 1A is a common target of circulating autoantibodies in several autoimmune diseases

Prior investigations demonstrated that autoantibodies recognizing cytosolic 5′‐nucleotidase 1A (NT5C1A) are found in 33–76% of patients with inclusion body myositis (IBM) but are observed only rarely in patients with polymyositis (PM). Thus, anti‐NT5C1A may help distinguish IBM from PM. Although 4–21% of patients with dermatomyositis (DM) were shown to be anti‐NT5C1A antibody positive, the clinical features of anti‐NT5C1A–positive patients with DM have not been described. Furthermore, the prevalence of anti‐NT5C1A antibodies in other rheumatic conditions has not been reported. This study was undertaken to define the prevalence and clinical features of anti‐NT5C1A–positive patients with DM, PM, IBM, or other systemic autoimmune diseases.

Overlapping features of polymyositis and inclusion body myositis in HIV-infected patients

Objective: To characterize patients with myositis with HIV infection. Methods: All HIV-positive patients with myositis seen at the Johns Hopkins Myositis Center from 2003 to 2013 were included in this case series. Muscle biopsy features, weakness pattern, serum creatine kinase (CK) level, and anti–nucleotidase 1A (NT5C1A) status of HIV-positive patients with myositis were assessed. Results: Eleven of 1,562 (0.7%) patients with myositis were HIV-positive. Myositis was the presenting feature of HIV infection in 3 patients. Eight of 11 patients had weakness onset at age 45 years or less. The mean time from the onset of weakness to the diagnosis of myositis was 3.6 years (SD 3.2 years). The mean of the highest measured CK levels was 2,796 IU/L (SD 1,592 IU/L). On muscle biopsy, 9 of 10 (90%) had endomysial inflammation, 7 of 10 (70%) had rimmed vacuoles, and none had perifascicular atrophy. Seven of 11 (64%) patients were anti-NT5C1A-positive. Upon presentation, all had proximal and distal weakness. Five of 6 (83%) patients followed 1 year or longer on immunosuppressive therapy had improved proximal muscle strength. However, each eventually developed weakness primarily affecting wrist flexors, finger flexors, knee extensors, or ankle dorsiflexors. Conclusions: HIV-positive patients with myositis may present with some characteristic polymyositis features including young age at onset, very high CK levels, or proximal weakness that improves with treatment. However, all HIV-positive patients with myositis eventually develop features most consistent with inclusion body myositis, including finger and wrist flexor weakness, rimmed vacuoles on biopsy, or anti-NT5C1A autoantibodies.

Association of Anti–3-Hydroxy-3-Methylglutaryl-Coenzyme A Reductase Autoantibodies With DRB1*07:01 and Severe Myositis in Juvenile Myositis Patients

Autoantibodies recognizing 3‐hydroxy‐3‐methylglutaryl‐coenzyme A reductase (HMGCR) are associated with statin exposure, the HLA allele DRB1*11:01, and necrotizing muscle biopsies in adult myositis patients. The aim of this study was to characterize the features of juvenile anti‐HMGCR‐positive myositis patients.

Anti–3-hydroxy-3-methylglutaryl-coenzyme a reductase necrotizing myopathy masquerading as a muscular dystrophy in a child

Immune‐mediated necrotizing myopathies (IMNMs) are characterized by progressive weakness, elevated serum creatine kinase levels, and necrotizing myopathic features on muscle biopsy. Presence of highly specific autoantibodies against signal recognition particle (SRP) or 3‐hydroxy‐3‐methylglutaryl‐ coenzyme A reductase (HMGCR) can aid in recognition and confirmation of IMNMs.

Anti-HMGCR necrotizing myopathy masquerading as a muscular dystrophy in a child

Immune‐mediated necrotizing myopathies (IMNMs) are characterized by progressive weakness, elevated serum creatine kinase levels, and necrotizing myopathic features on muscle biopsy. Presence of highly specific autoantibodies against signal recognition particle (SRP) or 3‐hydroxy‐3‐methylglutaryl‐ coenzyme A reductase (HMGCR) can aid in recognition and confirmation of IMNMs.

Anti‐3‐Hydroxy‐3‐Methylglutaryl‐Coenzyme A Reductase Autoantibodies are Associated with DRB1*07:01 and Severe Myositis in Pediatric Myositis Patients

Autoantibodies recognizing 3‐hydroxy‐3‐methylglutaryl‐coenzyme A reductase (HMGCR) are associated with statin exposure, the HLA allele DRB1*11:01, and necrotizing muscle biopsies in adult myositis patients. The aim of this study was to characterize the features of juvenile anti‐HMGCR‐positive myositis patients.

Anti-NT5C1A autoantibodies are associated with more severe disease in patients with juvenile myositis

Objectives Autoantibodies recognising cytosolic 5′-nucleotidase 1A (NT5C1A) are found in adult patients with myositis and other autoimmune diseases. They are especially prevalent in adults with inclusion body myositis (IBM), in which they are associated with more severe weakness and higher mortality. This study was undertaken to define the prevalence and clinical features associated with anti-NT5C1A autoantibodies in juvenile myositis. Methods We screened sera from 380 patients with juvenile myositis, 30 patients with juvenile idiopathic arthritis (JIA) and 92 healthy control children for anti-NT5C1A autoantibodies. Clinical characteristics were compared between patients with myositis with and without anti-NT5C1A autoantibodies. Results Anti-NT5C1A autoantibodies were present in 102 of 380 (27%) patients with juvenile myositis and in 11 of 92 (12%) healthy control children (P=0.002) and 27% of children with JIA (P=0.05 vs controls). Sera of 83 of 307 (27%) patients with juvenile dermatomyositis and 16 of 46 (35%) patients with juvenile overlap myositis were anti-NT5C1A autoantibody-positive (P<0.01 vs healthy controls for each), but sera of only 3 of 27 (11%) patients with juvenile polymyositis were anti-NT5C1A-positive. Patients with juvenile myositis with and without anti-NT5C1A autoantibodies had similar clinical phenotypes. However, patients with anti-NT5C1A autoantibody-positive myositis had greater pulmonary symptoms at diagnosis (P=0.005), more frequent hospitalisations (P=0.01) and required a larger number of medications (P<0.001). Conclusion Anti-NT5C1A autoantibodies are present in more than one-quarter of children with juvenile myositis and JIA compared with only 12% of healthy children, suggesting they are myositis-associated in children. As in adults with IBM, patients with juvenile myositis with anti-NT5C1A autoantibodies have more severe disease.

Pre-existing antiacetylcholine receptor autoantibodies and B cell lymphopaenia are associated with the development of myositis in patients with thymoma treated with avelumab, an immune checkpoint inhibitor targeting programmed death-ligand 1

Immune checkpoint inhibitors enhance the immune response against tumours but may also trigger immune-related adverse events (IRAEs). Myositis is a rare IRAE. For example, creatine kinase (CK) elevations occurred in just 0.3% of those treated with avelumab, an antiprogrammed death-ligand 1 antibody.1 Thymomas are the most common anterior mediastinal masses in adults. Since effective systemic therapies for thymic epithelial tumours are lacking, we included seven patients with recurrent thymoma and one patient with recurrent thymic carcinoma in a phase I trial of avelumab (NCT01772004). Details regarding this trial have been published separately.2 Myasthenia gravis and myositis occur in up to 30% and 5% of patients with thymoma, respectively.3 Although no patient had a history of autoimmunity or weakness and each had normal baseline CK levels, four patients developed weakness and elevated CK levels, ranging from 762 IU/L to 16 037 IU/L, within 5 weeks of avelumab administration (see online supplementary text and table 1). CK levels normalised in patients within weeks of stopping avelumab and starting immunosuppressive therapy. Of note, …