Protective Effect of Intestinal Helminthiasis Against Tuberculosis Progression Is Abrogated by Intermittent Food Deprivation

Abstract

Background: Tuberculosis (TB) is still a major challenge for humankind. Because regions with the highest incidence also have a high prevalence of helminthiasis and nutritional scarcity, we wanted to understand the impact of these on TB progression.

Methods: We have developed an experimental murine model for active TB in C3HeB/FeJ, coinfected with Trichuris muris and Heligmosomoides polygyrus nematodes, and exposed to an environmental mycobacterium (M. manresensis) and intermittent fasting. Cause-effect relationships among these factors were explored with Partial Least Squares Path modelling (PLSPM).

Results: Previous parasitization had a major anti-inflammatory effect and reduced systemic levels of ADA, haptoglobin, local pulmonary levels of IL-1β, IL-6, TNF-α, CXCL-1, CXCL-5 and IL-10. Oral administration of heat-killed M. manresensis resulted in a similar outcome. Both interventions diminished pulmonary pathology and bacillary load, but intermittent food deprivation reduced this protective effect increasing stress and inflammation. The PLSPM revealed nematodes might have protective effects against TB progression.

Conclusions: Significantly higher cortisol levels in food-deprivation groups showed it is a stressful condition, which might explain its deleterious effect. This highlights the impact of food security on TB eradication policies and the need to prioritize food supply over deworming activities.

Keywords: C3HeB/FeJ; Heligmosomoides polygyrus; Trichuris muris; co-infection; environmental mycobacteria Mycobacterium manresensis; fasting; tuberculosis.

Figure 1

Experimental design. Six groups of 10 animals were used to evaluate the influence of intestine parasitization, intermittent fasting and oral exposure to environmental mycobacteria in an active TB model.

Figure 2

Change of animals’ body condition. (A) Median weight of mice as infection progresses, infection day being time 0. (B) PCA based on liver and kidneys weight at end-point time. (C) PC1 scores, each circle represents an animal and lines are means; ANOVA p-value=0.0004, Holm-Sidak’s multiple comparisons test (*p < 0.05, **p < 0.01). hkMm, heat-killed M. manresensis.

Figure 3

Damage area (A) and pulmonary bacillary load (B) at week 3 post-infection. Each circle represents a “recut” (A) or an animal (B) and lines show medians. Mann-Whitney test: *p<0.05, **p<0.01, ***p<0.001. hkMm, heat-killed M. manresensis.

Figure 4

Oxidative stress analysis at week 3 post-infection. (A) PCA based on mediator concentration in serum. (B) PC1 scores, each circle represents an animal and lines are means; ANOVA p-value=0.0001, Holm-Sidak’s multiple comparisons test (*p < 0.05, **p < 0.01, ***p < 0.001). (C) Mediators contribution to PC1. hkMm, heat-killed M. manresensis; TEAC, trolox equivalent antioxidant capacity; CUPRAC, cupric reducing antioxidant capacity; FRAP, ferric reducing antioxidant power; PON1, paraoxonase 1; ROS, reactive oxygen species; AOPP, advanced oxidation protein products.

Figure 5

Adenosine deaminase (ADA) (A), haptoglobin (B) and cortisol (C) levels in serum at week 3 post-infection. Each circle represents an animal and lines are medians, Mann-Whitney test (*p<0.05, **p<0.01, ***p<0.001). hkMm, heat-killed M. manresensis.

Figure 6

Immune mediator analysis at week 3 post-infection. (A) PCA based on cytokines concentration in lung homogenates. (B) PC1 scores, each circle represents an animal and lines are means; ANOVA p-value=0.0067, Holm-Sidak’s multiple comparisons test (*p < 0.05, **p < 0.01). (C) Mediators contribution to PC1. hkMm, heat-killed M. manresensis.

Figure 7

Refined partial least square path model. Red arrows indicate a negative relation among latent variables (path coefficient bellow 0) and blue arrows indicate a positive one (path coefficient over 0).