Parasitology

  • Parasitology / Volume 138 / Issue 01 / January 2011, pp 35-45
  • Copyright © Cambridge University Press 2010. The online version of this article is published within an Open Access environment subject to the conditions of the Creative Commons Attribution-NonCommercial-ShareAlike licence <http://creativecommons.org/licenses/by-nc-sa/2.5/>. The written permission of Cambridge University Press must be obtained for commercial re-use.
  • DOI: http://dx.doi.org/10.1017/S0031182010000922 (About DOI), Published online: 12 July 2010
  • OPEN ACCESS

Research Article

Low levels of transforming growth factor-beta (TGF-beta) and reduced suppression of Th2-mediated inflammation in hyperreactive human onchocerciasis

S. KORTENa1a1 c1, A. HOERAUFa1, J. T. KAIFIa2 and D. W. BÜTTNERa3

a1 Institute for Medical Microbiology, Immunology and Parasitology, University of Bonn, Sigmund-Freud-Strasse 25, D-53105 Bonn, Germany

a2 Department of General, Visceral and Thoracic Surgery, University Medical Centre Hamburg-Eppendorf, Martinistrasse 52, D-20246 Hamburg, Germany

a3 Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Strasse 74, D-20359 Hamburg, Germany

SUMMARY

Th2-biased inflammation with eosinophilia and IgE production is a hallmark of helminth infections. It is pronounced in hyperreactive onchocerciasis patients (‘sowda’ or ‘local form’), who efficiently kill microfilariae resulting in severe dermatitis and lymphadenitis. In contrast, hyporeactive patients (‘generalised form’) tolerate high microfilarial loads. This is thought to be mediated by regulatory CD4+ T cells and macrophages producing suppressive cytokines such as IL-10 and transforming growth factor-beta (TGF-β). We investigated whether hyperreactivity was reflected by lower local TGF-β production, analysing stable latent TGF-β1 expression in onchocercomas, lymph nodes and skin from hyperreactive and hyporeactive patients by immunohistochemistry. TGF-β expression was compared with that of IgE, IgG1, IgG4, and the antigen-presenting, CD4+ T cell-inducing MHC class II molecule HLA-DR. TGF-β was weakly and less frequently expressed by various cell types in onchocercomas, skin and lymph nodes from hyperreactive compared to hyporeactive patients. This applied to reactions around living and dead adult worms as well as dead microfilariae. Antigen-presenting cells strongly expressed HLA-DR in both forms, but their numbers were reduced in hyperreactive nodules. Plasma cells produced more IgE and IgG1, but less of the anti-inflammatory antibody IgG4 in hyperreactive onchocercomas. In conclusion, hyperreactivity is linked with reduced local expression of TGF-β, HLA-DR and IgG4, which might contribute to the insufficient down-regulation of inflammation via TGF-β- and HLA-DR-induced regulatory lymphocytes.

(Received November 12 2009)

(Revised February 28 2010)

(Revised May 16 2010)

(Accepted May 17 2010)

(Online publication July 12 2010)

Correspondence:

c1 Corresponding author: Institute for Medical Microbiology, Immunology and Parasitology, University of Bonn, Sigmund-Freud-Strasse 25, D-53105 Bonn, Germany. Tel: +49 228 287 5673. Fax: +49 228 287 9573. E-mail: korten@microbiology-bonn.de

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