Immune response to gut Escherichia coli and susceptibility to adjuvant arthritis in the rats.

We have investigated the humoral immune response to antigens of predominant gut aerobic bacterial strains (i.e. Escherichia coli) over the course of adjuvant arthritis and oil-induced arthritis in two inbred rat strains: Dark Agouti (DA) and Albino Oxford (AO).

Strain differences in the humoral immune response to commensal bacterial antigens in rats.

We have investigated the immune response to commensal bacterial species in the two inbred rat strains: Dark Agouti (DA) and Albino Oxford (AO). The predominant Gram-negative aerobe in our rats' intestinal bacterial flora was Escherichia coli, while Proteus mirabilis was isolated only from DA rat strain. We report that sera from both DA and AO rat strains contain specific IgG against predominant intestinal flora.

Modulation of granulocyte functions by peptide YY in the rat: age-related differences in Y receptors expression and plasma dipeptidyl peptidase 4 activity.

It has been acknowledged that aging exerts detrimental effects on cells of the innate immune system and that neuropeptides, including neuropeptide Y (NPY) and NPY-related peptides fine-tune the activity of these cells through a receptor specific mechanism. The present study investigated the age-dependent potential of peptide YY (PYY) to modulate different granulocyte functions. The PYY reduced the carrageenan-elicited granulocyte accumulation into the air-pouch of aged (24 months) rats, and markedly decreased the phagocytosis of zymosan, as well as the H(2)O(2) production, when applied in vivo (20 microg/air-pouch).

The anti-inflammatory effect of neuropeptide Y (NPY) in rats is dependent on dipeptidyl peptidase 4 (DP4) activity and age.

Neuropeptide Y (NPY)-induced modulation of the immune and inflammatory responses is regulated by tissue-specific expression of different receptor subtypes (Y1-Y6) and the activity of the enzyme dipeptidyl peptidase 4 (DP4, CD26) which terminates the action of NPY on Y1 receptor subtype. The present study investigated the age-dependent effect of NPY on inflammatory paw edema and macrophage nitric oxide production in Dark Agouti rats exhibiting a high-plasma DP4 activity, as acknowledged earlier. The results showed that NPY suppressed paw edema in adult and aged, but not in young rats.

The effects of corticosterone and beta-endorphin on adherence, phagocytosis and hydrogen peroxide production of macrophages isolated from Dark Agouti rats exposed to acute stress.

Background: Given that stressful experiences can change the reaction to a subsequent exposure to stress, we tested the in vitro effects of the stress mediator corticosterone and the opioid peptide beta-endorphin on the function of macrophages isolated from control rats and from rats exposed to electric tail shock stress (ES) or a stress-witnessing procedure (SW) 24 h earlier.

Methods: Peritoneal macrophages isolated from control and stressed rats of the Dark Agouti (DA) strain were treated in vitro with corticosterone or beta-endorphin and tested for adherence, phagocytosis and hydrogen peroxide release.

Results: ES diminished adherence and SW decreased phagocytosis.

CD45 regulates TLR-induced proinflammatory cytokine and IFN-beta secretion in dendritic cells.

CD45 is a leukocyte-specific protein tyrosine phosphatase and an important regulator of AgR signaling in lymphocytes. However, its function in other leukocytes is not well-understood. In this study, we examine the function of CD45 in dendritic cells (DCs).

Methionine-enkephalin modulation of hydrogen peroxide (H2O2) release by rat peritoneal macrophages involves different types of opioid receptors.

We investigated the involvement of specific types of opioid receptors in methionine-enkephalin (MET)-induced modulation of hydrogen peroxide (H2O2) release by rat macrophages primed with sub-optimal concentrations of phorbol myristate acetate (PMA). Peritoneal macrophages in vitro treated with different concentrations of MET were tested for H2O2 release in phenol red assay. In the antagonistic study macrophages were treated with MET and one opioid receptor antagonist, or combination of MET and two or three opioid receptor antagonists.

Reactive oxygen species (ROS), but not nitric oxide (NO), contribute to strain differences in the susceptibility to experimental arthritis in rats.

There is extensive evidence for the critical role of reactive oxygen species (ROS) and nitric oxide (NO) produced by phagocytes in development of inflammatory processes and pathogenesis of numerous diseases, including rheumatoid arthritis (RA). Apart from their function as mediators of inflammation and tissue damage, recent research supports their role as signaling and regulatory molecules. In the present study we have investigated the production of ROS and NO over the course of adjuvant arthritis (AA) and oil-induced arthritis (OIA), by resident peritoneal macrophages of two rat strains: Dark Agouti (DA), susceptible, and Albino Oxford (AO), resistant to induction of AA and OIA.

Stress applied during primary immunization affects the secondary humoral immune response in the rat: involvement of opioid peptides.

The effect of unpredictable, inescapable and uncontrollable electric tail shocks (ES) on the humoral immune response to bovine serum albumin (BSA) was investigated in the rat. Contributions of the procedures that accompany shock delivery, such as witnessing the ES procedure (stress witnessing, SW) and exposure to the apparatus for shock delivery (apparatus control, AC) to the changes in specific immunity induced by ES were also tested. All procedures were applied during primary and/or secondary immunization.

Correlation between age-related changes in open field behavior and plaque forming cell response in DA female rats.

We investigated the relationship between immunological and behavioral changes during ageing in Dark Agouti female rats. Results showed that ageing was associated with decreased exploratory behavior and increased emotionality (open field test) and decreased pain perception (writhing assay), but not with altered depression-like behavior (forced swim test). The observed behavioral changes were paralleled with decreased innate immunity in middle-aged and old rats, as revealed by reduced peroxide production of peritoneal macrophages; and decreased specific immunity, measured by the plaque-forming cell response, in old rats in comparison with young rats.