Expression of the 60 and 70 kDa Family of Heat Shock Proteins in Trachea Epithelium Cells of Poults Experiencing Bordetellosis

Heat shock protein (HSP) gene families are known to be expressed preferentially over normal cellular proteins when poultry cells are exposed to environmental stressors. Bordetella avium infection leads to bordetellosis, which is characterized by severe inflammation of the tracheal epithelium, representing a severe stressor for the infected turkey poult. The purpose of this experiment was to examine the expression of HSP60 and HSP70 in the tracheae of B. avium-challenged poults. Tracheae were dissected from five poults per treatment at 7, 11, 14, and 21 days of age, and snap-frozen rings were examined immunohistochemically for the presence of HSP60 and HSP70 using HSP60 and HSP70 monoclonal antibodies (MABs). Infected poults expressed HSP60 predominantly on the apical surface of ciliated epithelial cells and weakly near the nucleus, and HSP70 was expressed only in the cytoplasm. Early in the development of bordetellosis, infected poults expressed more HSP60 and HSP70 than control poults of the same age, but at 14 days after infection, infected birds showed significantly decreased HSP60 proteins, which was associated with loss of tracheal epithelium. With loss of tracheal epithelium, the expression of HSP70 decreased at 11 days in the infected poults, and by day 21, very low levels of the proteins were observed in the infected poults compared to control poults with intact tracheal epithelium. It was concluded that decreased expression of HSP60 was indicative of HSP60 proteins becoming antigenic targets for the host’s immune system since immunologically targeted B. avium cells express GroEL (highly conserved HSP60 family equivalent) and DnaK (highly conserved HSP70 equivalent). The potential targeting of host and pathogen HSP60 by the innate immune system could feasibly facilitate loss of tracheal epithelium during the development of bordetellosis.