Pemphigus Vulgaris Successfully Treated With Doxycycline Monotherapy

Tetracyclines have multiple biological activities in addition to their antimicrobial function that may provide a therapeutic benefit in PV. They possess immunomodulatory and anti-inflammatory effects by inhibiting leukocyte chemotaxis and activation^4-8 and inhibiting cytokine release. They inhibit matrix metalloproteinases, which are the major enzymes responsible for breakdown of the extracellular matrix,⁹ and they indirectly inhibit neutrophil elastase by protecting α₁-protease inhibitor from matrix metalloproteinase degradation.¹⁰ Additionally, tetracyclines increase the cohesion of the dermoepidermal junction¹¹; whether they increase the adhesion between epidermal cells is unknown. It has been determined that CD4⁺ T cells play an essential role in the pathogenesis of PV by promoting anti-desmoglein 3 antibody production.¹² Szeto et al¹³ reported that minocycline, a member of the tetracycline family, has suppressive effects on CD4⁺ T-cell activation by hindering the activation of nuclear factor of activated T cells (NFAT), a key regulatory factor in T-cell activation. We hypothesize that doxycycline exerted what appears to be immunomodulatory properties in our patient by suppressing CD4⁺ T-cell activity.

In conclusion, tetracyclines can be an effective and promising therapy for PV given their relatively few side effects and immunomodulating properties. However, further randomized controlled trials will be important to support our conclusion.