Exacerbation of group B streptococcal sepsis and arthritis in diabetic mice.

Group B streptococci (GBS) have been recognised as an ever-growing cause of serious invasive infections in non-pregnant adults, in particular in association with severe underlying diseases such as diabetes mellitus. In the present study we used mice rendered diabetic to gain further insights into host-pathogen interaction during induced GBS sepsis and septic arthritis. Type I diabetes was induced in adult CD-1 mice by low-dose streptozotocin treatment. Mice were then infected with different doses of GBS, and mortality, appearance of arthritis, growth of microorganisms in the organs and cytokine and chemokine profile were assessed in diabetic and control animals. The LD50 was significantly lower in diabetics than in controls, while both incidence and severity of arthritis were higher. A significantly higher number of microorganisms were recovered from the organs of diabetic mice than in controls. The worsening of sepsis and arthritis was associated with a significant increase in systemic and local production of IL-6, IL-1 beta, TNF-alpha, IL-10, macrophage inflammatory protein 1 alpha (MIP-1alpha), and MIP-2 and with a decrease in IFN-gamma production. Taken together, our results indicate an impaired host resistance to GBS infection in diabetics, likely due to a dysregulation of the cytokine network and prolonged local inflammatory response.

Glycogen synthase kinase-3beta inhibition attenuates the degree of arthritis caused by type II collagen in the mouse.

Recently, glycogen synthase kinase-3 (GSK-3) has being identified as an ubiquitous serine-threonine protein kinase that participates in a multitude of cellular processes and plays an important role in the pathophysiology of a number of diseases. The aim of this study was to investigate the effects of GSK-3beta inhibition on the degree of arthritis caused by type II collagen (CII) in the mouse (collagen-induced arthritis; CIA). Mice developed erosive hind paw arthritis when immunized with CII in an emulsion in complete Freund's adjuvant (CFA). The incidence of CIA was 100% by day 28 in the CII-challenged mice and the severity of CIA progressed over a 35-day period with radiographic evaluation revealing focal resorption of bone. The histopathology of CIA included erosion of the cartilage at the joint margins. Treatment of mice with the GSK-3beta inhibitor TDZD-8 (1 mg/kg/day i.p.) starting at the onset of arthritis (day 25) ameliorated the clinical signs at days 26-35 and improved histological status in the joint and paw. Immunohistochemical analysis for nitrotyrosine, poly(ADP-ribose) (PAR), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) revealed a positive staining in inflamed joints from mice subjected to CIA. The degree of staining for nitrotyrosine, PAR, iNOS, and COX-2 was significantly reduced in CII-challenged mice treated with the GSK-3beta inhibitor. Plasma levels of tumor necrosis factor (TNF)-alpha and the joint tissue levels of macrophage inflammatory protein (MIP)-1alpha and MIP-2 were also significantly reduced by GSK-3beta inhibition. These data demonstrate that GSK-3beta inhibition exerts an anti-inflammatory effect during chronic inflammation and is able to ameliorate the tissue damage associated with CIA.

Antibodies to macrophage inflammatory protein-1beta in preoptic area of rats fail to suppress PGE2 hyperthermia.

This study determined whether macrophage inflammatory protein-1beta (MIP-1beta) plays a role in the hyperthermia caused by prostaglandin E2 (PGE2) given intracerebroventricularly (i.c.v.) in the rat. In these experiments, anti-murine MIP-1beta antibody (anti-MIP-1beta) was micro-injected in the anterior hypothalamic, preoptic area (AH/POA) just before i.c.v. PGE2. The results showed that anti-MIP-1beta failed to alter the PGE2 hyperthermia. However, immunocytochemical studies revealed MIP-1beta immunoreactivity detectable in both the organum vasculosum laminae terminalis (OVLT) and AH/POA in the febrile rat. These data thus demonstrate that MIP-1beta is sequestered in diencephalic structures underlying thermoregulation even though it is not involved in PGE2 hyperthermia. This dissociation supports the viewpoint that at least two distinct systems exist in the brain which underlie a febrile response: MIP-1beta underlies one component whereas PGE2 comprises the other.