Administration of kefir-fermented milk protects mice against Giardia intestinalis infection

MARIANA CORREA FRANCO; GOLOWCZYC M. A.; GRACIELA DE ANTONI; PABLO PÉREZ; MARTÍN HUMEN; MARÍA DE LOS ANGELES SERRADELL

JOURNAL OF MEDICAL MICROBIOLOGY

SOC GENERAL MICROBIOLOGY

Lugar: London; Año: 2013 p. 1815 - 1822

0022-2615

   Giardiasis, caused by the protozoan Giardia intestinalis, is one of the most common intestinaldiseases worldwide and constitutes an important problem for the public health systems of variouscountries. Kefir is a probiotic drink obtained by fermenting milk with ?kefir grains?, which consistmainly of bacteria and yeasts that coexist in a complex symbiotic association. In this work, westudied the ability of kefir to protect mice from G. intestinalis infection, and characterized the hostimmune response to this probiotic in the context of the intestinal infection. Six- to 8-week-oldC75BL/6 mice were separated into four groups: controls, kefir mice (receiving 1 : 100 dilution ofkefir in drinking water for 14 days), Giardia mice (infected orally with 4107 trophozoites of G.intestinalis at day 7) and Giardia?kefir mice (kefir-treated G. intestinalis-infected mice), and killedat 2 or 7 days post-infection. Kefir administration was able to significantly reduce the intensity ofGiardia infection at 7 days post-infection. An increase in the percentage of CD4+ T cells at2 days post-infection was observed in the Peyer?s patches (PP) of mice belonging to the Giardiagroup compared with the control and kefir groups, while the percentage of CD4+ T cells in PP inthe Giardia?kefir group was similar to that of controls. At 2 days post-infection, a reduction in thepercentage of B220-positive major histocompatibility complex class II medium cells in PP wasobserved in infected mice compared with the other groups. At 7 days post-infection, Giardiainfectedmice showed a reduction in RcFce-positive cells compared with the control group,suggesting a downregulation of the inflammatory response. However, the percentages of RcFcepositivecells did not differ from controls in the kefir and Giardia?kefir groups. An increase in IgApositivecells was observed in the lamina propria of the kefir group compared with controls at2 days post-infection. Interestingly, the diminished number of IgA-positive cells registered in theGiardia group at 7 days post-infection was restored by kefir feeding, although the increase in IgApositivecells was no longer observed in the kefir group at that time. No significant differences inCXCL10 expression were registered between groups, in concordance with the absence ofinflammation in small-intestinal tissue. Interestingly, a slight reduction in CCL20 expression wasobserved in the Giardia group, suggesting that G. intestinalis might downregulate its expressionas a way of evading the inflammatory immune response. On the other hand, a trend towards anincrease in TNF-a expression was observed in the kefir group, while the Giardia?kefir groupshowed a significant increase in TNF-a expression. Moreover, kefir-receiving mice (kefir andGiardia?kefir groups) showed an increase in the expression of IFN-c, the most relevant Th1cytokine, at 2 days post-infection. Our results demonstrate that feeding mice with kefir reduces G.intestinalis infection and promotes the activation of different mechanisms of humoral and cellularimmunity that are downregulated by parasitic infection, thus contributing to protection.