Anti-synthase syndrome

What is antisynthetase? syndrome?

Antisynthetase syndrome is a rare inflammatory muscle disease related to dermatomyositis and polymyositis.

The hallmark of antisynthetase syndrome is the presence of serum autoantibodies directed against aminoacyl-tRNA synthetases. These are cellular enzymes involved in protein synthesis. antisynthetase antibodies they include Jo-1, PL-7, PL-12, OJ, EJ, KS, Wa, YRS, and Zo. Anti-Jo-1 antibodies are the most commonly detected in antisynthetase syndrome.

Antisynthetase syndrome is 2–3 times more common in women than in men.

What causes antisynthetase syndrome?

The cause of antisynthetase syndrome is unknown. It is classified as a chronic autoimmune disease.

How does antisynthetase syndrome present?

The main clinical features of antisynthetase syndrome are:

• Fever
• myositis (muscle inflammation)
• Polyarthritis (inflammation in various joints)
• Interstitial lung disease (non-specific inflammation of the lungs)
• mechanic hands
• Raynaud's phenomenon

Antisynthetase syndrome can present with a variety of clinical features and these can vary over time.

Fever

• Present in approximately 20% of patients
• It can occur early in the disease.
• May persist or recur relapses

myositis

• Present in >90% of patients
• Associated with anti Jo-1 antibodies
• Proximal muscle weakness causes difficulty getting up from a chair or climbing stairs
• The muscles can be sore.
• Weakness of the muscles involved in swallowing can cause aspiration pneumonia.
• Weakness of the respiratory muscles can cause shortness of breath.

Inflammatory arthritis

• 50% of patients experience joint pain or arthritis
• More often symmetrical arthritis of small joints of the hands and feet
• Usually does not result in bone erosions

Lung disease

• Interstitial lung disease develops in most patients with anti-Jo-1 antisynthetase syndrome.
• Often presents with sudden or gradual onset of shortness of breath with exercise
• Sometimes causes intractable dry cough
• Can lead to pulmonary hypertension (increased pressure in the pulmonary arteries) in patients with or without concomitant interstitial lung disease.

mechanic hands

• It affects approximately 30% of patients.
• Thickened skin of the tips and margins of the fingers.
• It resembles the hands of a mechanic.

Raynaud's phenomenon

• It occurs in approximately 40% of patients.
• An episodic reduction in the blood supply of the fingers and toes that turn white, then blue, and finally red
• A response to cold or emotional stress.
• Some patients have associated nail fold capillary abnormalities

Symptoms of antisynthetase syndrome

Association with malignancy

Some case studies have reported various malignancies occurring within 6 to 12 months of diagnosis of antisynthetase syndrome. Therefore, age-appropriate screening is recommended, as for dermatomyositis.

How is the diagnosis of antisynthetase syndrome made?

The clinical presentation is a clue to the diagnosis of antisynthetase syndrome. Special investigations help support the diagnosis. These may include the following depending on the clinical context:

• Muscle enzymes, for example, creatinine kinase (CK) and aldolase: these are often elevated
• muscle antibodies
• Electromyography (EMG)
• Magnetic resonance imaging (Magnetic resonance) of the affected muscles
• Muscle biopsy
• Lung function tests
• High resolution computed tomography scan (Connecticut) of the chest
• Assessment of swallowing difficulties and risk of aspiration.
• lung biopsy

How is antisynthetase syndrome treated?

Glucocorticosteroids they are the mainstay of treatment for antisynthetase syndrome and are often required for several months or years. Prednisone is initially given in high doses (1 mg/kg/day) for 4 to 6 weeks to achieve disease control, then tapered slowly over 9-12 months to the lowest effective dose to maintain remission. In more severe cases, pulsed intravenous (IV) methylprednisolone for 3-5 days may be necessary.

Improvement in muscle strength can take several weeks or months. Symptomatic improvement is a more reliable indicator of response to treatment than serum CK levels.

Prophylactic Treatment for steroid-induced osteoporosis and certain fungal infections such as Pneumocystis jirovecii is recommended. The need for vaccinations should be evaluated before starting therapy.

Other immunosuppressive drugs may be used, such as:

• Azathioprine
• Methotrexate
• Cyclophosphamide
• Tacrolimus
• Cyclosporine
• Mycophenolate
• Rituximab

Physical therapy and rehabilitation should begin early to prevent muscle deconditioning and improve weakness.

Forecast of antisynthetase syndrome

Patients with antisynthetase syndrome respond well to systemic steroids and/or immunosuppressive agents if they only have muscle involvement.

If the lungs are involved, the severity and type of lung injury determine the prognosis. Advanced age at onset (>60 years), presence of malignancy, and negative ANA antibody the test confers a worse prognosis.