Expression of Toll-Like Receptors (TLR2 and TLR4) in the Eyes of Mice with Disseminated Acanthamoebiasis

Abstract

Toll-like receptors (TLRs) play a key role in the innate immune response to numerous pathogens, including Acanthamoeba spp. The aim of this study was to determine the expression of TLR2 and TLR4 in the eyes of mice following intranasal infection with Acanthamoeba spp. in relation to the host's immunological status. Amoebae used in this study were isolated from the bronchial aspirate of a patient with acute myeloid leukemia (AML) and atypical symptoms of pneumonia. We found statistically significant differences in the expression of TLR2 and TLR4 in the eye of immunocompetent mice at 8, 16, and 24 days after Acanthamoeba spp. infection (dpi) compared to control group. Immunosuppressed mice showed significant differences in the expression of TLR2 at 16 and 24 dpi compared to uninfected animals. Our results indicate that TLR2 and TLR4 are upregulated in the eyes of mice in response to Acanthamoeba spp. We suggest that it is possible for trophozoites to migrate through the optic nerve from the brain to the eyes. The course of disseminated acanthamoebiasis may be influenced by the host's immunological status, and the observed changes in expression of TLR2 and TLR4 in the host's organs may indicate the role of these receptors in the pathomechanism of acanthamoebiasis.

Figure 1

Schematic diagram of conducted experiment (group C: uninfected immunocompetent mice; group CS: uninfected mice treated with an immunosuppressive drug; group A: Acanthamoeba spp. infected immunocompetent mice; group AS: Acanthamoeba spp. infected mice treated with an immunosuppressive drug).

Figure 2

The mRNA expression of the tlr2 gene in the eye of uninfected (0 dpi) and infected mice at 8, 16, and 24 days after Acanthamoeba spp. infection (dpi), according to the immunological status of hosts (A: immunocompetent mice; AS: immunosuppressed mice). The data represent mean ± standard deviation (SD) for eight independent experiments; ∗p<0.05, ∗∗p<0.01, compared with control value from uninfected mice (Mann–Whitney U test).

Figure 3

The mRNA expression of the tlr4 gene in the eye of uninfected (0 dpi) and infected mice at 8, 16, and 24 days after Acanthamoeba spp. infection (dpi), according to the immunological status of hosts (A: immunocompetent mice; AS: immunosuppressed mice). Data represent mean ± standard deviation (SD) for eight independent experiments; ∗p<0.05, ∗∗p<0.01, compared with control value from uninfected mice (Mann–Whitney U test).

Figure 4

Immunohistochemical staining with primary anti-TLR2 antibodies in the corneas (a, c, e, g, i, k, m, o) and retinas (b, d, f, h, j, l, n, (p)) of immunocompetent (a, b, e, f, i, j, m, n) and immunosuppressed mice (c, d, g, h, k, l, o, p) from control groups (0 dpi) and at 8, 16, and 24 days after Acanthamoeba spp. infection (dpi). Magnification x40 (black arrows: corneal epithelium; red arrows: external limiting membrane, Bowman's membrane; white stars: stroma of cornea, substantia basalis; yellow arrows: Descemet's membrane; blue arrows: corneal endothelium; white arrows: optic nerve fiber layer; green arrows: inner plexiform layer; orange arrows: outer plexiform layer; pink arrows: layer of rods and cones).

Figure 5

Immunohistochemical staining with primary anti-TLR4 antibodies in the corneas (a, c, e, g, i, k, m, o) and retinas (b, d, f, h, j, l, n, (p)) of immunocompetent (a, b, e, f, i, j, m, n) and immunosuppressed mice (c, d, g, h, k, l, o, p) from control groups (0 dpi) and at 8, 16, and 24 days after Acanthamoeba spp. infection (dpi). Magnification x40 (black arrows: corneal epithelium; red arrows: external limiting membrane, Bowman's membrane; white stars: stroma of cornea, substantia basalis; yellow arrows: Descemet's membrane; blue arrows: corneal endothelium; white arrows: optic nerve fiber layer; green arrows: inner plexiform layer; orange arrows: outer plexiform layer; pink arrows: layer of rods and cones).