Uncoupling of osteoblast-osteoclast regulation in a chemical murine model of Gaucher disease.

Gaucher disease (GD) is caused by mutations in the GBA gene that confer a deficient level of activity of glucocerebrosidase (GCase). This deficiency leads to accumulation of the glycolipid glucocerebroside in the lysosomes of cells of monocyte/macrophage system. Type I GD is the mildest form and is characterized by the absence of neuronopathic affection. Bone compromise in Gaucher disease patients is the most disabling aspect of the disease. However, pathophysiological aspects of skeletal alterations are still poorly understood. The homeostasis of bone tissue is maintained by the balanced processes of bone resorption by osteoclasts and formation by osteoblasts. We decided to test whether bone resorption and/or bone formation could be altered by the use of a chemical in vitro murine model of Gaucher disease. We used two sources of cells from monocyte/macrophages lineage isolated from normal mice, splenocytes (S) and peritoneal macrophages (PM), and were exposed to CBE, the inhibitor of GCase (S-CBE and PM-CBE, respectively). Addition of both conditioned media (CM) from S-CBE and PM-CBE induced the differentiation of osteoclasts precursors from bone marrow to mature and functional osteoclasts. TNF-α could be one of the factors responsible for this effect. On the other hand, addition of CM to an osteoblast cell culture resulted in a reduction in expression of alkaline phosphatase and mineralization process. In conclusion, these results suggest implication of changes in both bone formation and bone resorption and are consistent with the idea that both sides of the homeostatic balance are affected in GD.

Interleukin-12p40 contributes to protection against lung injury after oral Yersinia enterocolitica infection.

OBJECTIVE: The impact of Yersinia enterocolitica on lung is incompletely understood, so we studied the inflammatory effects of Yersinia oral infection and the influence of IL-12p40 deficiency. METHODS: Wild-type (WT) and IL-12p40-/- (KO) mice were orally infected with Y. enterocolitica 0:3. After 3 and 21 days, cell viability in bronchoalveolar lavage (BAL) fluid, inflammatory reactions, lipid hydroperoxides, antioxidant enzyme expression and histological changes were studied. RESULTS: An effect on the lung was demonstrated by changes in lactate dehydrogenase, total protein (p <0.001), nitrosative stress and increase numbers of lymphocyte in the BAL fluid. All of these appeared to be IL-12 - independent since statistically significant changes in response to infection (at 21 days) did not differ between WT and KO groups. However, a protective role of IL-12 after infection was suggested by a decrease in cell viability, histopathological changes, different cell populations, higher lipid peroxidation and a decrease in antioxidant enzymes - glutathione peroxidase, superoxide dismutase-2 (p <0.05). The main changes were detected at day 21 suggesting a chronic effect of Yersinia infection and that IL-12 could play a role in the protection against chronic sequelae in the lung. CONCLUSIONS: These results demonstrate that Y. enterocolitica infection may induce inflammatory response in lung and that IL-12p40 could contribute to protection against lung injury.

Microflora reactive IL-10 producing regulatory T cells are present in the colon of IL-2 deficient mice but lack efficacious inhibition of IFN-gamma and TNF-alpha production.

BACKGROUND: Inflammatory bowel disease in interleukin 2 (IL-2) deficient (IL-2(-/-)) mice is triggered by the intestinal microflora and mediated by CD4(+) T cells. AIMS: To determine the characteristics of microflora specific intestinal T cells, including migration and cytokine production. METHODS: Intestinal T cell populations and cytokine mRNA expression of specific pathogen free (SPF) and germ free (GF) IL-2(-/-) and IL-2(+/+) mice were compared by flow cytometry and reverse transcription-polymerase chain reaction. Cytokine production of intestinal mononuclear cells on stimulation with microflora antigens was assessed by ELISA. In vivo migration of T cells was assessed by adoptive transfer of (51)Cr labelled CD4(+)CD25(-)alpha beta(+) T cells. The ability of intestinal T cell lines to promote colitis was determined by adoptive transfer experiments. RESULTS: SPF IL-2(-/-) mice produced higher interferon gamma (IFN-gamma) and tumour necrosis factor alpha mRNA levels than GF IL-2(-/-) mice, which was accompanied by an increased number of CD4(+)alpha beta T cells in the colon. Tracking of (51)Cr labelled and adoptively transferred T cells revealed an increased MAdCAM-1 dependent but VCAM-1 independent recruitment of these cells into the colon of SPF IL-2(-/-) mice. Colon lamina propria lymphocytes (LPL) from SPF IL-2(-/-) mice showed increased spontaneous IFN-gamma production in vitro. On stimulation with bacterial microflora antigens, intraepithelial lymphocytes and LPL did not produce IFN-gamma, but high quantities of IL-10, which did not suppress IFN-gamma production. Bacterial antigen specific cell lines established from colon LPL of SPF IL-2(-/-) mice with colitis showed a regulatory T cell-like cytokine profile and only marginally modulated the course of colitis and survival of IL-2(-/-) mice. CONCLUSIONS: Our results suggest that microflora reactive regulatory T cells are present in the colon of SPF IL-2(-/-) mice. However, IL-10 produced by these cells did not significantly modulate a possible secondary proinflammatory CD4 Th1 cell population to produce IFN-gamma.