The pathogenesis of and susceptibility to malabsorption syndrome in broilers is associated with heterophil influx into the intestinal mucosa and epithelial apoptosis

Abstract

Malabsorption syndrome (MAS) in broilers is characterized by enteritis and reduced body weight gain. The pathogenesis of the intestinal lesions and the reasons for susceptibility differences between broiler lines are not clear. We studied the development of enteric lesions, epithelial apoptosis, and cell proliferation in relation to susceptibility. One-day-old chickens from two broiler lines were orally inoculated with intestinal homogenate derived from MAS-affected chickens. Vacuolar degeneration and apoptosis of the villous epithelium and infiltration of heterophils into the lamina propria occurred from day 1 post-inoculation. Following heterophil accumulation, at day 4 to 6 post-inoculation, there was severe apoptosis of the crypt epithelium and villous atrophy. The susceptible broilers had a significantly greater influx of heterophils and, subsequently, severe epithelial apoptosis and cystic damage to the crypts. There appeared to be a causal relationship between heterophil influx and the onset of apoptosis. Coincident with the epithelial apoptosis, MAS-affected chickens had crypt hyperproliferation and faster epithelial turnover. Heterophil infiltration and epithelial apoptosis appear to be critical in the pathogenesis of MAS. Heterophil recruitment may be a major factor in differences in susceptibility to MAS.

Malabsorption syndrome in broilers

“…From the T-cell profiles together with the cytokine mRNA profiles of the intestines it was concluded that the susceptible line reacted with a more cell mediated T-helper response to a MAS infection compared to the "resistant" line. This is in agreement with the recruitment that was observed of cytotoxic T-cells and heterophils (Songserm et al, 2002a;Zekarias et al, 2005). Such insufficient or uncontrolled reactivity at the mucosal surfaces might lead to the severe damage that was observed in the intestine of the sensitive line.…”

“…In another study Zekarias et al (2005)showed that in the onset of MAS there was an association between heterophil influx and the onset of apoptosis of the crypt epithelium. MAS induced chickens showed crypt hyperproliferation and increased epithelial turnover.…”

“…A disturbance in maintenance of the intestine by apoptosis and proliferation could play a role in the pathogenesis of the mucosal lesions in MAS. Zekarias et al (2005), studied the early pathogenesis of the mucosal lesions in experimentally MAS affected chickens by comparing the leukocyte response in the intestinal mucosa, epithelial apoptosis and proliferation. The intestinal mucosal lesions in MAS affected chickens developed vacuolar degeneration and apoptosis of the villous epithelial cells at day 1 post inoculation.…”

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“…Ten age-matched control birds received 0.2 ml of vaccine diluent. After 4 wk, turkeys were challenged with 2 3 10 6 50% embryo infectious doses (EID 50 ) per bird of the SM05 pathogenic virus delivered intranasally. The challenge dose was equivalent with 2000 of the 50% bird lethal doses.…”

Modelo de protocolo experimental para induzir, classificar e avaliar as enterites inespecíficas em frangos de corte

“…Porém, existem ainda várias condições negativas que podem resultar em problemas entéricos em frangos de corte, que afetam a digestão de nutrientes da dieta, o equilíbrio da microbiota intestinal e, consequentemente, os parâmetros de produção (Zekarias et al 2005, Teirlynck et al 2011.…”