Table 1.
Sequences of the sense and antisense primers used for quantitative real time RT-PCR.
Table 2.
Effect of PBS- or clodronate-containing liposomes on body weight (in grams) and gene expression (fold change) of M1 and M2 macrophage markers in response to N. brasiliensis infection.
Figure 1.
Macrophage depletion improves the N. brasiliensis-induced decrease in glucose absorption, but not in epithelial resistance.
WT mice were given PBS or clodronate (Cl2MDP) containing liposomes to deplete macrophages and one day later treated with vehicle (VEH) or infected with N. brasiliensis (Nb). At day nine post inoculation, muscle-free mucosae were mounted in Ussing chambers to determine (A) mucosal resistance and (B) concentration dependent changes in epithelial sodium-linked glucose absorption. Values shown are means ± SE; *p<0.05 vs VEH Control.
Figure 2.
Nippostrongylus. brasiliensis infection alters the expression of glucose transporters.
WT mice were treated with vehicle (VEH) or were infected with N. brasiliensis (Nb). At day nine post inoculation, full thickness sections of small intestine were prepared for (A) real-time qPCR to measure the mRNA expression of glucose transporters (B) Western blot analyses for glucose transporters, using actin as a loading control and (C) immunofluorescence staining for glucose transporters on the surface of villi of small intestine. The photomicrographs are representative of five different replicate slides. Values shown are means ± SE; p<0.05 vs VEH Control.
Figure 3.
The effect of macrophage depletion on N. brasiliensis infection-induced changes in the expression of glucose transporters.
WT mice were given PBS or clodronate (Cl2MDP) containing liposomes to deplete macrophages and one day later treated with vehicle (VEH) or infected with N. brasiliensis (Nb). At day nine post inoculation, full thickness sections of small intestine were prepared for real-time qPCR to measure the mRNA expression of glucose transporters. Values shown are means ± SE; *p<0.05 vs VEH Control; φp<0.05 vs N. brasiliensis infected mice treated with PBS-containing liposomes.
Figure 4.
Immune regulation of glucose transporter expression and localization of GLUT1 and GLUT2 transporters.
WT or STAT6−/− mice were treated with vehicle (VEH) or were infected with N. brasiliensis (Nb). At day nine post infection, full thickness sections of small intestine were prepared for real-time qPCR to determine the mRNA expression of (A) GLUT1 or (B) GLUT2. WT mice were treated with vehicle (VEH) or were infected with N. brasiliensis (Nb). At day nine post inoculation, sections of small intestine were prepared for laser capture micro-dissection (LCM) to determine (C) GLUT1 or (D) GLUT2 mRNA expression in epithelial cells or in the lamina propria. Values shown are means ± SE; **p<0.05 vs VEH Control; φp<0.05 vs WT N. brasiliensis.
Figure 5.
Macrophage depletion alters expression of factors involved in small intestinal glucose homeostasis.
WT mice were given PBS or clodronate (Cl2MDP) containing liposomes to deplete macrophages and one day later treated with vehicle (VEH) or infected with N. brasiliensis (Nb). At day nine post-inoculation, full thickness sections of small intestine were prepared for real-time qPCR to determine the mRNA expression of RELM-β leptin, or HIF-1α. Values shown are means ± SE, *p<0.01 vs. VEH Control; φp<0.05 vs N. brasiliensis-infected mice treated with PBS-containing liposomes.
Figure 6.
Model for changes in epithelial glucose handling in response to N. brasiliensis infection.
(1) Infection induces a STAT6-dependent increase in mucosal permeability and (2) recruitment of alternatively activated macrophages (M2). (3) There is a M2-dependent inhibition of epithelial SGLT1 activity and M2-independent down-regulation of GLUT2. (4) This stresses the cell leading to activation of HIF-1α and up-regulation of the constitutive insulin-dependent GLUT1. This transporter serves as the major mechanism for glucose entry into the cell. Thus, parasitic nematode infection results in a “lean” epithelial phenotype as a result of a shift from insulin-dependent to insulin-independent glucose transporters. The increased permeability (1) enhances the contribution of paracellular absorption of glucose to maintain body weight during infection.