Cyclophosphamide augments inflammation by reducing immunosuppression in a mouse model of allergic airway disease.
BACKGROUND
Allergic asthma is a TH2 cell-driven immunological disease, characterized by eosinophilic inflammation. The cytotoxic agent cyclophosphamide paradoxically augments several immune responses.


OBJECTIVE
We studied the proposal that cyclophosphamide may aggravate airway inflammation in allergic mice, and these features might result from the loss of regulatory T cells.


METHODS
BALB/c mice were immunized with ovalbumin on days 0 and 14 and challenged with aerosolized ovalbumin from days 21 to 27. Some mice also received cyclophosphamide on days -2 and 12.


RESULTS
In the lungs of cyclophosphamide-treated animals, pronounced worsening of inflammatory features was noted, including increased eosinophil infiltration, epithelial thickness, mucus occlusion, and eosinophil numbers in bronchoalveolar lavage fluid. There was also increased total and ovalbumin-specific serum IgE, increased IL-4 and IL-5 secretion by peritracheal lymph node cells, and reduced lung mRNA expression of IL-10 and TGF-beta in animals treated with cyclophosphamide. The expression of FoxP3, a marker of regulatory T cells, was significantly reduced in lymphoid organs after the second injection of cyclophosphamide, and in the lung tissue after allergen challenge in cyclophosphamide-treated mice. Lung IL-10+CD4+ T cells and cytotoxic T lymphocyte-associated antigen 4+CD4+ T cells were reduced after allergen challenge in cyclophosphamide-treated mice.


CONCLUSIONS
Cyclophosphamide worsened features of allergic pulmonary inflammation in this model, in association with increased production of IgE and TH2 cytokines. The reduced expression of FoxP3 and immunosuppressive cytokines by cyclophosphamide is consistent with the possibility that toxicity to regulatory T cells may contribute to the increased inflammation.
Su
Yung-Chang
YC
Arthritis and Inflammation Research Program, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia.
Rolph
Michael S
MS
Cooley
Margaret A
MA
Sewell
William A
WA
D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D000485:Allergens; D000818:Animals; D001249:Asthma / Q000276:immunology*; D003520:Cyclophosphamide / Q000494:pharmacology*; D016207:Cytokines / Q000096:biosynthesis; D004195:Disease Models, Animal; D004804:Eosinophils / Q000276:immunology; D051858:Forkhead Transcription Factors / Q000096:biosynthesis; D007073:Immunoglobulin E / Q000096:biosynthesis; D016753:Interleukin-10 / Q000096:biosynthesis; D008168:Lung / Q000187:drug effects* / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D010047:Ovalbumin; D018418:Th2 Cells / Q000276:immunology; D016212:Transforming Growth Factor beta / Q000096:biosynthesis
D000276:Adjuvants, Immunologic; D000485:Allergens; D016207:Cytokines; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D016212:Transforming Growth Factor beta; D016753:Interleukin-10; D007073:Immunoglobulin E; D003520:Cyclophosphamide; D010047:Ovalbumin