Interferon-α induced remission in three patients with eosinophilic granulomatosis and polyangiitis. A case study

The Rash, the Weakness, and the Nephritis: Nerve and Kidney Biopsy Findings in Eosinophilic Granulomatosis With Polyangiitis

We present a case of eosinophilic granulomatosis with polyangiitis (EGPA) or Churg-Strauss syndrome in a 66-year Caucasian female who presented with a severe pruritic itch and a progressive upper and lower extremity weakness of unknown duration. The diagnosis of EGPA in this patient remained elusive for an extended period of time due to the absence of respiratory symptoms. In this article, we also discuss the histologic features of EGPA seen in biopsies of the kidney and the nerves and highlight the value they play in diagnosis.

Interferon at the crossroads of allergy and viral infections

IFN-α/β was first described as a potent inhibitor of viral replication, but it is now appreciated that IFN signaling plays a pleiotropic role in regulating peripheral T cell functions. Recently, IFN-α/β was shown to block human Th2 development by suppressing the transcription factor GATA3. This effect is consistent with the role for IFN-α/β in suppressing allergic inflammatory processes by blocking granulocyte activation and IL-4-mediated B cell isotype switching to IgE. With the consideration of recent studies demonstrating a defect in IFN-α/β secretion in DCs and epithelial cells from individuals with severe atopic diseases, there is an apparent reciprocal negative regulatory loop in atopic individuals, whereby the lack of IFN-α/β secretion by innate cells contributes to the development of allergic Th2 cells. Is it possible to overcome these events by treating with IFN-α/β or by inducing its secretion in vivo? In support of this approach, case studies have documented the therapeutic potential of IFN-α/β in treating steroid-resistant allergic asthma and other atopic diseases. Additionally, individuals with asthma who are infected with HCV and respond to IFN therapy showed a reduction in symptoms and severity of asthma attacks. These findings support a model, whereby allergic and antiviral responses are able to cross-regulate each other, as IgER cross-linking of pDCs prevents IFN-α/β production in response to viral infection. The clinical importance of upper-respiratory viruses in the context of allergic asthma supports the need to understand how these pathways intersect and to identify potential therapeutic targets.