Host defences against Giardia lamblia

Abstract

Giardia spp. is a protozoan parasite that inhabits the upper small intestine of mammals and other species and is the aetiological agent of giardiasis. It has been demonstrated that nitric oxide, mast cells and dendritic cells are the first line of defence against Giardia. IL-6 and IL-17 play an important role during infection. Several cytokines possess overlapping functions in regulating innate and adaptive immune responses. IgA and CD4(+) T cells are fundamental to the process of Giardia clearance. It has been suggested that CD4(+) T cells play a double role during the anti-Giardia immune response. First, they activate and stimulate the differentiation of B cells to generate Giardia-specific antibodies. Second, they act through a B-cell-independent mechanism that is probably mediated by Th17 cells. Several Giardia proteins that stimulate humoral and cellular immune responses have been described. Variant surface proteins, α-1 giardin, and cyst wall protein 2 can induce host protective responses to future Giardia challenges. The characterization and evaluation of the protective potential of the immunogenic proteins that are associated with Giardia will offer new insights into host-parasite interactions and may aid in the development of an effective vaccine against the parasite.

Hematological profile in natural progression of giardiasis: kinetics of experimental infection in gerbils

“…These results would be expected if we consider that Giardia does not invade tissues and will not induce significant cell infiltration [17]. However, the parasite can induce local and systemic inflammatory response [18]. The intensity of this response could relate to the ability of certain strains in injure tissues.…”

Significance of Nitric Oxide Level in Giardiasis

“…IgA is important and is a major mechanism as it contributes to the elimination of Giardia intestinalis. Non-specific inflammatory mediators such as IL-1 and TNF-α lead to stimulation of goblet cells which produce mucosa to facilities elimination of dead parasites [9,18,19]. Besides the production of antibodies, another important mechanism that causes inactivation and death of the parasite is production of NO (nitric oxide).…”

“…These include anti-microbial peptides, NO, and mast cell products [28,29]. In most humans, infected with Giardia lamblia, the parasites are effectively eliminated by the immune system [18,19]. NO has been recognized as playing an important role in the control of infections with numerous microbes.…”

Effect of probiotics on giardiasis. Where are we?

“…Both innate and adaptive immunity mechanisms are essential for the elimination of the parasite from the intestine. Innate immunity mechanisms are the first line of defense, and among them are the mucus, peristalsis, cytotoxic factors, nitric oxide, microbiota, mast cells, and dendritic cells (Lopez-Romero et al, 2015). Mast cells have the potential to interfere directly or indirectly in the duodenal growth of G. lamblia trophozoites; they are essential to control G. lamblia infection, especially due to the IL-6 synthesis.…”