Immunomodulatory effects and mechanisms of plant alkaloid tetrandrine in autoimmune diseases.

Autoimmune diseases characterized by activation of immune effector cells and
damage of target organs are currently treated with a combination of several
disease-modifying antirheumatic drugs (DMARDs) that preserve different
immunomodulatory mechanisms. Such a combination treatment strategy not only
provides synergistic effects but also reduces side effects from individual drug.
Tetrandrine (Tet), purified from a creeper Stephania tetrandra S Moore, is a
bis-benzylisoquinoline alkaloid and has been used to treat patients with
silicosis, autoimmune disorders, and hypertension in Mainland China for decades.
The accumulated studies both in vitro and in vivo reveal that Tet preserves a
wide variety of immunosuppressive effects. Importantly, the Tet-mediated
immunosuppressive mechanisms are evidently different from some known DMARDs. The
synergistic effects have also been demonstrated between Tet and other DMARDs like
FK506 and cyclosporin. These results highlight Tet a very potential candidate to
be considered as one of DMARDs in the treatment of autoimmune diseases,
especially rheumatoid arthritis. This review summarizes evidence-based in vivo
and in vitro studies on this potential Chinese immunosuppressive herb.