Prenatal alcohol exposure alters the course and severity of adjuvant-induced arthritis in female rats

Abstract

Prenatal alcohol exposure (PAE) has adverse effects on the development of numerous physiological systems, including the hypothalamic-pituitary-adrenal (HPA) axis and the immune system. HPA hyper-responsiveness and impairments in immune competence have been demonstrated. The present study investigated immune function in PAE females utilizing an adjuvant-induced arthritis (AA) model, widely used as a model of human rheumatoid arthritis. Given the effects of PAE on HPA and immune function, and the known interaction between HPA and immune systems in arthritis, we hypothesized that PAE females would have heightened autoimmune responses, resulting in increased severity of arthritis, compared to controls, and that altered HPA activity might play a role in the immune system changes observed. The data demonstrate, for the first time, an adverse effect of PAE on the course and severity of AA in adulthood, indicating an important long-term alteration in functional immune status. Although overall, across prenatal treatments, adjuvant-injected animals gained less weight, and exhibited decreased thymus and increased adrenal weights, and increased basal levels of corticosterone and adrenocorticotropin, PAE females had a more prolonged course of disease and greater severity of inflammation compared to controls. In addition, PAE females exhibited blunted lymphocyte proliferative responses to concanavalin A and a greater increase in basal ACTH levels compared to controls during the induction phase, before any clinical signs of disease were apparent. These data suggest that prenatal alcohol exposure has both direct and indirect effects on inflammatory processes, altering both immune and HPA function, and likely, the normal interactions between these systems.

Figure 1. Incidence and severity of arthritis

1A. Percentage of adjuvant-injected females from prenatal Control (C, ad libitum-fed), Pair-fed (PF), and Alcohol-fed (PAE, prenatal alcohol exposure) groups that developed clinical signs of arthritis over the 39 day time course. Day 0–16, PF>C, p=0.04; PF > E, p<0.077). Day 17–39, PAE>PF=C, p<0.05. 1B. Clinical scores of individual females from prenatal Control (C, ad libitum-fed), Pair-fed (PF), and Alcohol-fed (PAE, prenatal alcohol exposure) groups in the day 39 cohort over time. 1C. Area under curve (AUC) (mean±SEM) as a quantitative measure of incidence of arthritis in females from prenatal Control (C, ad libitum-fed), Pair-fed (PF), and Alcohol-fed (PAE, prenatal alcohol exposure) groups over the 39 day time course. *PAE>PF=C, p<0.05; ^#PAE>PF=C, p<0.06.

Figure 2. Activation status (mean±SEM) of lymph node CD4⁺ T cells

Percentage of activated CD4⁺ T cells expressing the activation markers CD25, CD44H, CD45RC, and CD62L in saline- and adjuvant-injected females, as assessed by flow cytometry. *p<0.05**p<0.01, ***p<0.001, compared to Saline-injected females.

Figure 3. Lymph node CD4⁺CD134⁺ T cells

Percentage (mean±SEM) of activated CD4⁺ T cells expressing the activation marker CD134⁺ in saline- and adjuvant-injected females from prenatal Control (C, ad libitum-fed), Pair-fed (PF), and alcohol-fed (PAE, prenatal alcohol exposure) groups, as assessed by flow cytometry. ***p<0.001 vs saline-injected females; #p<0.10 vs C females.

Figure 4. Proliferative response (mean±SEM) of lymphocytes from draining lymph nodes on d 7, 16 and 39 post-adjuvant injection

³H-thymidine incorporation expressed as counts per minute (CPM). 4A. Day 7: Adjuvant>saline, ***p<0.001; Collapsed across condition, PAE<PF=C, **p<0.01. 4B. Day 16: In the Adj/NA condition, PAE<PF=C, ***p<0.001 and ^#p<0.06, respectively. 4C. Day 39: Collapsed across condition, PF<PAE=C, **p<0.01.

Figure 5. HPA hormone profiles

Left column: Plasma CORT levels (mean±SEM) on d 7 (A), 16 (B) and 39 (C) after injection. Day 7: Adj>saline, *p<0.05; Day 16: Adj/AA>Adj/NA>saline, ^#p=0.065; *p<0.05); Day 39: Adj/AA>saline, *p<0.05. Right column: Plasma ACTH levels (mean±SEM) on d 7 (D), 16 (E) and 39 (F) after injection. Day 7: Adj>saline, ***p<0.001; within Adj, PAE>PF=C, **p<0.01; Day 16: Adj/AA>Adj/NA>saline, *p<0.05, ^#p=0.068.