Genetics

HLA class II alleles and haplotypes that confer susceptibility or protection in systemic sclerosis (SSc) vary between different ethnic groups. Arnett et al. characterized multiple clinical and genetic features of 1,300 patients with SSc (961 white, 178 black and 161 Hispanic) and 1,000 healthy individuals. The researchers found that the DRB1*1104/DQA1*0501/DQB1*0301 haplotype and DQB1 alleles were associated with SSc in white and Hispanic patients, while SSc in black individuals was correlated with the presence of DRB1*0804, DQA1*0501 and DQB1*0301 alleles. These findings might have implications for the development of genetic tests for SSc based on HLA class II alleles and haplotypes.

Rheumatoid arthritis

Patients with rheumatoid arthritis receiving methotrexate often take additional medications for comorbidities, which raises the concern of alterations in the efficacy and toxicity of methotrexate as a result of drug interactions. The authors of a recent systematic review, which included 78 case reports, 21 pharmacokinetic studies and 5 observational studies, have concluded that methotrexate has limited drug interactions. However, the concomitant use of trimethoprim–sulfamethoxazole is a risk factor for cytopenia. Furthermore, cases of both cytopenia and mild abnormalities of liver enzymes have been reported when methotrexate is used in combination with some NSAIDs, including acetylsalicyclic acid.

Lupus nephritis

New evidence suggests that patients with lupus nephritis refractory to mycophenolate mofetil treatment might benefit from the addition of tacrolimus, although complete responses were rare and tacrolimus toxicity was observed. The investigators retrospectively analyzed data from seven patients: one achieved a complete renal remission and three achieved partial remission with 82.9%, 77.1% and 55.3% reductions in proteinuria. However, five patients had to discontinue the combination therapy as a result of adverse side-effects, such as diabetic ketoacidosis, pneumonia and muscle pain. Thus, the toxicity of tacrolimus might limit its long-term use in these patients.