Interleukin-1 receptor deficiency in the hippocampal formation of (NZB x NZW)F2 mice: genetic and molecular studies relating to autoimmunity

Effect of sleep deprivation on the corticosterone secretion in an experimental model of autoimmune disease

OBJECTIVE

Sleep disturbances have been observed in a number of chronic inflammatory conditions, such as systemic lupus erythematosus. Previous results from our laboratory showed that when NZB/NZWF1 mice, an experimental model of lupus, are submitted to sleep deprivation (SD), they exhibit an earlier onset of the disease. Sleep disturbances have far-reaching effects on the endocrine and immune system, changes that may be linked to disease manifestation. Immunoendocrine communication via the hypothalamic-pituitary-adrenal axis has been proposed as an important modulatory factor for the development of autoimmune disease. We hypothesized here that corticosterone (CORT) could be involved in earlier onset of the disease in sleep-deprived NZB/NZWF1 mice.

METHODS

The profile of CORT secretion was measured immediately after the end of SD (platform method) and during the development of the disease. Also, we analyzed the effects of SD on CORT secretion of Swiss albino mice, which do not present immune alterations.

RESULTS

The results showed that NZB/NZWF1 mice exhibited a CORT response to SD similar to Swiss albino mice. However, CORT levels remained elevated throughout the whole period of evaluation. There was an increase in circulating levels of CORT in the NZB/NZWF1 mice as the disease progressed, but this effect was more evident in the sleep-deprived mice.

CONCLUSION

According to these results, we suggest that elevated CORT levels are involved in the earlier onset of the disease.

Involvement of MyD88 in host defense and the down-regulation of anti-heat shock protein 70 autoantibody formation by MyD88 in Toxoplasma gondii-infected mice

This study investigated the influence of TLR (toll-like receptor)4, TLR2, and MyD88 in Toxoplasma gondii-infected wild-type (WT) mice and TLR4-, TLR2-, and MyD88-deficient mice. Ninety-five percent of MyD88-deficient mice died 10-16 days after intraperitoneal infection with 100 cysts of T. gondii Fukaya strain, whereas 95-100% of TLR4- and TLR2-deficient mice and WT C57BL/6 (B6) mice survived for more than 7 wk after T. gondii infection. The distribution of T. gondii in various organs of TLR4-, TLR2-, and MyD88-deficient mice and WT B6 mice was assessed 2 wk after T. gondii intraperitoneal infection using quantitative competitive polymerase chain reaction. In MyD88-deficient mice, high levels of T. gondii load were observed in the brain, tongue, heart, lungs, spleen, liver, mesenteric lymph node, and kidneys after infection. The T. gondii load was significantly increased in the lungs in both TLR4- and TLR2-deficient mice compared with WT B6 mice. High levels of anti-mouse heat shock protein (mHSP)70 autoantibody and anti-T. gondii HSP70 antibody production were detected in the sera from MyD88-deficient mice.

Increased sensitivity of prediabetic nonobese diabetic mouse to the behavioral effects of IL-1

The nonobese diabetic (NOD) mouse is a model of spontaneous insulin-dependent diabetes mellitus (IDDM) or type I diabetes. In humans, and in animal models of IDDM, the progression of the disease is modulated by various environmental factors, particularly infectious agents. Interleukin-1 (IL-1) plays a pivotal role in the development of IDDM, and modulation of its synthesis may be a mechanism by which environmental modulation of disease progression occurs. Since various alterations at the level of the gene, number, and sensitivity of IL-1 receptors have been described in different animal models of autoimmune disease, we investigated, in the prediabetic NOD mouse, the presence of IL-1 receptors and their functional behavioral characteristics. Here we present evidence that prediabetic NOD mice exhibit a normal distribution and density of functional brain IL-1 receptors, but are more sensitive to the behavioral effects of IL-1 than the control ICR strain.

Animal models of neuroimmune interactions in inflammatory diseases

Animal models have been used successfully to study various aspects of neural-immune interactions. Although different approaches carry certain advantages and disadvantages, current high sensitivity screening and manipulation methods coupled with molecular and genetic approaches can be successfully used to tease out the neural pathways that regulate inflammatory disease and the effects of immune molecules, such as interleukins, on neuronal function and pathology. Newer methodologies that measure gene expression of thousands of genes will in the future add to the ability to evaluate complex systems interactions in whole animal models. This review addresses the advantages and disadvantages of some of these approaches in the context of application to neural-immune interactions.

Expression of interleukin-1 genes and interleukin-1 receptors in the mouse brain after hippocampal injury

In order to evaluate the role of IL-1 production in post-traumatic brain, transcripts for IL-1 (alpha, beta, RA) have been quantified following RT-PCR, in hippocampus and cortex after injury of either hippocampus (Hip) or striatum (Stri). Moreover, 125I IL-1alpha binding sites have been directly quantified using binding experiments on brain sections and quantitative autoradiography. Under basal conditions, levels of PCR products were very low. On day 1, IL-1RA transcripts only were strongly increased in the hippocampus after Hip-lesions and in cortex after Stri lesion. Transcripts were back to control values on day 7 post-lesion. IL-1 receptor densities in the hippocampus (dentate gyrus) were decreased at day 1 around the site of the lesion (but not on the contralateral side) and were back to controls on day 7 indicating a transient and local IL-1 production in the surroundings of the lesion. No changes were found following Stri lesion. This study provides further evidence of the role of the IL-1 molecules family, notably IL-1RA, in the brain reaction to trauma.