Enhancing the activity of disulfide-bond-containing proteins via promoting disulfide bond formation in Bacillus licheniformis.

Disulfide bonds in proteins have strongly influence on the folding efficiency by constraining the conformational space. The inefficient disulfide bond formation of proteins is the main limiting factor of enzyme activity and stability. This study aimed to increase the activity of disulfide-bond-containing proteins via promoting disulfide bonds formation in Bacillus licheniformis. Initially, the glutamate decarboxylase GAD from Escherichia coli was selected as the model protein and introduced into the B. licheniformis. Then, the disulfide isomerase and oxidoreductase from different sources were excavated and overexpressed successively to improve the catalytic efficiency of GAD. The final engineered B. licheniformis showed significantly improved GAD specific activity (from 10.4 U/mg to 80.0 U/mg), which also presented perfect adaptability for other disulfide-bond-containing proteins, for instance, UDP-glucosyltransferase from Arabidopsis thaliana. Taken together, our work demonstrated that the activity of GAD in B. licheniformis was regulated by the disulfide bonds formation status and provided a promising platform for the expression of disulfide-bond-containing proteins.

Tocilizumab treatment in Felty's syndrome.

Felty's syndrome (FS) is a deforming disease, characterized by the triad of rheumatoid arthritis (RA), neutropenia, and splenomegaly. Currently, FS patients are treated mainly with immunosuppressants, such as methotrexate and glucocorticoids, which however are not suitable to some patients and may cause severe side effects. Here we report a clinical FS case that was treated with Tocilizumab (TCZ) successfully. The patient had symmetrical swelling and pain of multiple joints, deformity of elbow joints with obvious morning stiffness. Joint color Doppler ultrasound showed synovial hyperplasia and bone erosion of wrist and proximal interphalangeal joints and CT scan suggested splenomegaly. Further examination showed neutropenia and anemia, a high titer of anti-cyclic citrullinated peptide antibody, rheumatoid factor and anti-nuclear antibodies, positive p-ANCA, and elevated IgA and IgG. After treating with TCZ, the patient has been relieved of clinical symptoms. His spleen has recovered to normal size. The absolute neutrophil count (ANC) tended to be stable, and joint erosion did not deteriorate. We have reviewed the literatures on FS treatment with biological agents and found only a few reports using TNF-α antagonist and rituximab treating FS, but none with TCZ. So, it is the first time to report a successful FS case treated with TCZ. This case suggests that the TCZ may be a new choice for FS treatment, under the condition of closely monitoring the ANC.