The purpose of this large multicenter, randomized, double-blinded, controlled clinical study is to investigate the efficacy and safety of Cyclosporin A for primary Sjogren's syndrome associated pneumonitis(pSS-IP), which has important implications for the establishment of standardized diagnosis and treatment of pSS-IP.

Inclusion Criteria:

• Patients meeting the 2002 or 2012 pSS criteria;
• Patients meeting the diagnostic criteria of interstitial pneumonitis(IP);
• Patients with exertional dyspnea consistent with grade 2 on the Magnitude of Task component of the Mahler Modified Dyspnea Index;
• Pulmonary function test: patients with percentages of forced vital capacity (FVC) to predicted values≥45%, percentage of diffusing capacity of carbon monoxide (DLco) to predicted values≥30%, forced expiratory volume in one second (FEV1) / FVC> 65%;
• For patients who received oral glucocorticoid, the doses should be no more than 10 mg/d (or equivalent amount of other types of glucocorticoids);
• Patients who had not received any prior treatment with immunosuppressants (including but not limited to CYC, CsA, azathioprine(AZA), tacrolimus(FK-506), methotrexate, leflunomide, etc.) or had discontinued the therapy above for at least 3 months; for patients who received hydrochloroquine(HCQ), the doses should be stabilized for at least 3 months;
• Patients who had not received any prior treatment with biological agents, including but not limited to rituximab, infliximab, adalimumab, etanercept, etc., or had discontinued therapy for at least three months;
• For patients who had prior treatment with N-acetylcysteine, the doses of above drugs should be stabilized for at least 3 months;
• The women of reproductive age who had a negative urine pregnancy test. The women and men of reproductive age must receive effective contraceptive measures from the screening period to last administration of drugs;
• Patients who were able to read, to understand and to sign informed consent.

Exclusion Criteria: Patients who met any of the following criteria will not participate in this study.

• Patients with acute exacerbation of IP(AEIP);

• Arterial blood gas analysis showed respiratory failure;

• Patients with lung diseases other than IP:

  1. Patients with severe pulmonary hypertension who require specific treatments assessed by the rheumatology and immunology experts in various clinical centers;
  2. Patients with a history of smoking within the last 6 months or current smokers;
  3. Patients with other serious lung diseases, such as lung tumor or active pulmonary infection;
  4. Lung biopsy, alveolar lavage or high-resolution computerized tomography (HRCT) suggested serious lung diseases other than IP;

• Patients with other rheumatic autoimmune diseases, including but not limited to rheumatoid arthritis, systemic lupus erythematosus, inflammatory myopathy, systemic sclerosis, primary biliary cirrhosis, etc.;

• Patients with serious heart, liver, kidney diseases, hematologic and/ or endocrine diseases:

  1. Heart diseases: decompensated heart failure or refractory hypertension; clinically important abnormal ECG that may lead to unacceptable risks to enrolled patients at screening;
  2. Liver function: alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST) ≥2 times the upper limit of normal (ULN);
  3. Renal function: renal tubular and/or interstitial diseases, renal insufficiency: serum creatinine≥2 ULN or glomerular filtration rate (eGFR) <90 ml/min/1.73 m2;
  4. White blood cell (WBC) count <3 ×109/L and/or hemoglobin (Hb) <100 g/L and/or platelet (PLT) count <80×109 /L;
  5. Other serious diseases: such as cancer, etc.;

• Patients with active infection or other diseases which will be aggravated with treatment of glucocorticoid and immunosuppressive therapy;

• Patients positive for HBsAg or hepatitis C antibody;

• Women during pregnancy or lactation, or cannot guarantee effective contraception;

• Patients who did not cooperate with treatment for mental illness or other reasons;

• Patients who had allergic constitution or were allergic to many drugs;

• Patients who were allergic or intolerant to CsA, CYC, or glucocorticoid.