Microsporidia and its relation to Crohn's disease. A retrospective study

Abstract

Background: The cause of Crohn's Disease (CD) remains unknown. Recently a decrease in the global lymphocyte population in the peripheral blood of CD patients has been reported. This decrease was more evident in γδ T lymphocytes, especially γδ CD8+T subsets. Furthermore, a decrease of IL-7 was also observed in these patients. We propose the hypothesis that microsporidia, an obligate intracellular opportunistic parasite recently related to fungi, in CD patients can take advantage of the lymphocytes and IL-7 deficits to proliferate and to contribute to the pathophysiology of this disease.

Methods and findings: In this case-control study, serum samples were collected from 36 CD patients and from 36 healthy individuals (controls), IgE and IgG anti-Encephalitozoon antibodies were determined by ELISA; and forty-four intestinal tissue samples were analyzed through real time Polymerase Chain Reaction (PCR), twenty CD patients, nine with others diseases and 15 healthy subjects. We observed that IgE anti-Encephalitozoon levels were significantly higher in patients with CD: 0.386(±0.256) vs control group, 0.201(±0.147), P<0.001. However, IgG anti-Encephalitozoon values were significantly lower in CD patients: 0.361(±0.256) vs control group, 0.876(±0.380), P<0.001. In the group of CD patients, 6/20 (30%) were positive by real time PCR for microsporidia and, all the patients of the control group were negative by real time PCR.

Conclusions: These results suggest that CD patients are a group at risk for microsporidiasis and, moreover that microsporidia may be involved as a possible etiologic factor of CD.

Figure 1. Anti-Encephalitozon antibody levels measured by ELISA (IgE and IgG).

A: Crohn`s disease (N = 36) vs Control group (N = 36). B: Clinical scenarios of Crohn's disease, New patient (N = 13), Remission (N = 13), and Active disease (N = 10) vs Control group. Immunoglobulins are expressed in means of Optical Density (O.D.) values and T bars denote standard deviation. * P<0.001.

Figure 2. Correlation between immunoglobulins (IgG, IgE) anti-Encephalitozon and T cells subsets.

A, B, and C express, in CD patients, the correlation between IgE anti-Encephalitozoon and CD3+γδ T cells (−386, P = 0.02) and CD3+CD4+γδ T cells (−338, P = 0.047), and CD3+CD8+γδ T cells (−350, P = 0.037), respectively. D, healthy subjets, describes the correlation of IgE anti-Encephalitozoon with CD3+CD4+αβ T cells (−540, P<0.001). E and F represent the correlations obtained in CD patients between IgG anti-Encephalitozoon antibody levels and γδ T cells (+346, P = 0.039) and CD3+CD56+γδ T cells (+362, P = 0.03), respectively. Immunoglobulines are expressed as means of Optical Density (O.D.). T cell values are expressed as means (x 10⁹/L).

Figure 3. Values of T lymphocyte subsets according to type of receptor αβ (A) and γδ (B) in CD patients and Control Group.

CD patients (red bars) and control groups (blue bars). Significant differences (*) were observed in the case of CD3+αβ (P = 0.006), CD3+CD8+αβ (P = 0.018), CD3+γδ (P<0.001) and CD3+CD8+γδ (P = 0.003). The deficit of T lymphocytes in patients with CD with respect to the control group was more intense when γδ T cells were studied.

Figure 4. Tissue sampling of patient with CD.

A, Chronic inflammation with lymphoid nodules in the lamina propria with cryptitis and crypt microabscesses in some. Hematoxylin-eosin stain x 200. B, Structure composed of granulomatous histiocytic added. Hematoxylin-eosin stain x 200. C, Staining of undetermined structures in the macrophages next to a crypt gland. Modified Trichrome stain x 1000. D, Staining of undetermined structures in the macrophages next to a crypt gland in healthy control. Modified Trichrome stain x 1000.