Articles > Immune response after experimental allergic encephalomyelitis in rats subjected to calorie restriction

Immune response after experimental allergic encephalomyelitis in rats subjected to calorie restriction

Figure 1 shows final body weight (upper panel) and the evolution of the clinical scores of EAE in control and calorie restricted rats (lower panel). When analyzed as main factors in a factorial ANOVA, both calorie restriction and SCH injection decreased body weight significantly (F2,36 = 294, p 1,36 = 15.7, p = 0.0003).

Rats subjected to the normal diet or to a 33% calorie restriction exhibited clinical signs of the disease, starting on day 12 after SCH injection whereas, a 66%-calorie restriction effectively suppressed the course of EAE in Lewis rats (Fig. 1, lower panel). Rats receiving complete Freund’s adjuvant alone and subjected to none, 33% or 66% calorie restriction did not exhibit any sign of disease (results not shown).

Figure 2 depicts the mitogenic responses to Con A and LPS of cells derived from spleen or SmLN of control or calorie-restricted rats. In the case of splenic Con A mitogenic response, a significant interaction "diet x immunization" was found in factorial ANOVA (F2,36 = 3.48, p = 0.0415), i.e., SCH injection augmented Con A response in control and 33% calorie-restricted rats while decreased it under severe caloric restriction (Fig 2, upper left panel). Splenic cell response to LPS was higher in 66% calorie-restricted rats (F2,36 = 4.2, p = 0.0229, factorial ANOVA, Fig. 2, lower left panel).

In SmLN, a significant depression of Con A mitogenic activity was observed as a function of calorie restriction (F2,36 = 7.1, p = 0.0025, factorial ANOVA, Fig. 2, upper right panel). The changes in lymph node LPS mitogenic response (Fig. 2) or of mitogenic responses in thymic cells were not significant (results not shown).

Figures 3 to 5 summarize the data on the different immune cell populations in spleen, SmLN and thymus of control and calorie restricted rats. A significant stimulatory effect of SCH immunization on splenic, lymph node and thymic CD4+ cell number was found (F1,36 = 11.6, p = 0.0016; F1,36 = 27.1, p 1,36 = 18.8, p 3 to 5). A significant interaction "diet x immunization" was detected in the case of spleen and SmLN, SCH injection augmenting CD4+ cell number in control and moderately calorie-restricted, but not in severely calorie-restricted animals (F2,36 = 3.44. p = 0.0429 and F2,36 = 6.17, p = 0.005, for spleen and SmLN, respectively, factorial ANOVA, Fig. 3 and 4).

Calorie restriction depressed splenic and lymph node CD8+ cell number (F2,36 = 98.2, p 2,36 = 11.7, p = 0.0001, Fig. 3 and 4), with a significant interaction "diet x immunization" in the case of spleen (F2,36 = 11.9, p = 0.0001), i.e., the decrease in CD8+ cell number observed after SCH immunization in control and 33% calorie restricted rats was no longer found in 66% calorie-restricted animals (Fig. 3). Thymic CD8+ cells augmented after SCH immunization (F1,36 = 10.2, p = 0.0029, factorial ANOVA, Fig. 5). Consequently, CD4+/CD8+ ratios increased after calorie restriction or SCH immunization in spleen (F2,36 = 20.8, p 1,36 = 7.53, p = 0.0094) and SmLN (F2,36 = 4.77. p = 0.0145 and F1,36 = 26.5, p 3 and 4) and decreased after calorie restriction in thymus (F2,36 = 9.02, p = 0.0007, Fig. 5). Splenic double-labeled CD4+-CD8+ cells decreased after calorie restriction (F2,36 = 6.99, p = 0.0027, factorial ANOVA, Fig. 3).

In the spleen, T cell number decreased as a function of calorie restriction and augmented after SCH immunization (F2,36 = 43, p 1,36 = 11.8, p = 0.0015, factorial ANOVA, Fig. 3). The decrease of lymph node T cells seen in control following SCH immunization was not longer observed after a moderate or a severe calorie restriction (F2,36 = 5.91, p = 0.006 for the interaction "diet x immunization" in the factorial ANOVA, Fig. 4). Likewise, a significant interaction "diet x immunization" occurred for thymic T cell number, i.e., in contrast to the decrease after immunization seen in control and 33% calorie-restricted rats there was an increase in 66% calorie-restricted rats (F2,36 = 9.91, p = 0.0004 for the interaction "diet x immunization" in the factorial ANOVA, Fig. 5).

Splenic, lymph node and thymic B cell number decreased after calorie restriction (F2,36 = 22.3, 26.8 and 88, p 3 to 5). In the case of spleen and SmLN, significant interactions "diet x immunization" occurred (F2,36 = 3.39, p = 0.0448 and F2,36 = 8.16, p = 0.0012, respectively), the stimulatory effect of SCH immunization seen in controls being no longer observed in 33% or 66% calorie-deprived rats (Fig. 3 and 4). As a consequence, a significant interaction between diet and immunization occurred for T/B ratio in every tissue, i.e., the decrease after SCH injection taking place in controls disappeared or was reversed in calorie-restricted rats. Double labeled T-B cells in spleen and lymph nodes decreased markedly in severely calorie-restricted rats (p 3 and 4). A significant interaction "diet x immunization" was observed in the thymus (F2,36 = 5.81, p = 0.0065), T-B cells augmenting in 66% calorie restricted rats, but not in control or 33% calorie-restricted animals (Fig. 5).

The changes in IFN-γ production by splenic, lymph node and thymic cells are depicted in Fig. 6. Factor analysis in the factorial ANOVA indicated the existence of significant interactions "diet x immunization" in the case of splenic and lymph node cells. In contrast to the increase in splenic IFN-γ production occurring in control and 33% calorie-restricted rats after SCH immunization there was a decrease in 66% calorie-restricted rats (F2,36 = 8.93, p = 0.0007). A similar trend was observed for lymph node IFN-γ production (F2,36 = 3.37, p γ

production was severely curtailed in 66% calorie-restricted rats (F2,36 = 13.5, p


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