Patient Develops Psoriatic Arthritis After Multiple Wasp Stings

After reviewing the results of his labs, clinicians prescribed oral prednisone 40mg once daily, which after 3–4 doses provided considerable pain relief for the patient. In addition, methotrexate 10mg weekly was added to his regimen and was titrated up to 25mg weekly; the dose of prednisone, however, could not be reduced to less than 20mg/day. The patient was diagnosed with psoriatic arthritis associated with multiple wasp stings. Given the early onset, radiography did not reveal the typical changes seen with psoriatic arthritis, however this did not exclude the diagnosis. Although not performed on this patient, magnetic resonance imaging or ultrasonography can be used to detect early changes.

While rare, cases of arthritis associated with bee and wasp stings have been previously reported in the medical literature. Mastoparan, a peptide toxin found in wasp venom, can lead to activation of phospholipase A2 (PLA₂), an inflammatory mediator that has been implicated in psoriasis.  PLA₂ plays an integral part in the pathogenesis of psoriatic arthritis as well, as it has been found to activate natural killer (NK) cells. Moreover, patients with psoriasis have been found to have high concentrations of interleukin 15 in synovial fluid and serum; interleukin 15 further activates PLA₂ and primes NK cells for cytotoxic killing. 

In this patient “promotion of PLA₂ activity through interleukin 15 and resultant activation of NK cells has been implicated in the pathogenesis of PsA. Further investigation of the PLA₂ pathway in PsA may lead to novel therapeutic agents for the treatment of this debilitating arthropathy,” the authors concluded.

Reference

Vinyette Saco, T, MD. Glaum, M.C., MD. Ledford, D.K., MD. Lockey, R.F., MD. Onset of psoriatic arthritis associated with multiple wasp stings. Annals of Allergy, Asthma and Immunology. DOI: 10.1016