Toll-like receptor 4-mediated regulation of spontaneous Helicobacter-dependent colitis in IL-10-deficient mice.

BACKGROUND & AIMS: The commensal microbiota is believed to have an important role in regulating immune responsiveness and preventing intestinal inflammation. Intestinal microbes produce signals that regulate inflammation via Toll-like receptor (TLR) signaling, but the mechanisms of this process are poorly understood. We investigated the role of the anti-inflammatory cytokine interleukin (IL)-10 in this signaling pathway using a mouse model of colitis. METHODS: Clinical, histopathologic, and functional parameters of intestinal inflammation were evaluated in TLR4(-/-), IL-10(-/-), and TLR4(-/-) x IL-10(-/-) mice that were free of specific pathogens and in TLR4(-/-) x IL-10(-/-) mice following eradication and reintroduction of Helicobacter hepaticus. Regulatory T-cell (Treg) function was evaluated by crossing each of the lines with transgenic mice that express green fluorescent protein under control of the endogenous regulatory elements of Foxp3. Apoptotic cells in the colonic lamina propria were detected by a TUNEL assay. RESULTS: TLR4-mediated signals have 2 interrelated roles in promoting inflammation in TLR4(-/-) x IL-10(-/-) mice. In the absence of TLR4-mediated signals, secretion of proinflammatory and immunoregulatory cytokines is dysregulated. Tregs (Foxp3(+)) that secrete interferon-gamma and IL-17 accumulate in the colonic lamina propria of TLR4(-/-) x IL-10(-/-) mice and do not prevent inflammation. Aberrant control of epithelial cell turnover results in the persistence of antigen-presenting cells that contain apoptotic epithelial fragments in the colonic lamina propria of Helicobacter-infected TLR4(-/-) mice. CONCLUSIONS: In mice that lack both IL-10- and TLR4-mediated signals, aberrant regulatory T-cell function and dysregulated control of epithelial homeostasis combine to exacerbate intestinal inflammation.

Vaccine-induced antibody isotypes are skewed by impaired CD4 T cell and invariant NKT cell effector responses in MyD88-deficient mice.

The requirement for TLR signaling in the initiation of an Ag-specific Ab response is controversial. In this report we show that a novel OVA-expressing recombinant Salmonella vaccine (Salmonella-OVA) elicits a Th1-biased cell-mediated and serum Ab response upon oral or i.p. immunization of C57BL/6 mice. In MyD88(-/-) mice, Th1-dependent Ab responses are greatly reduced while Th2-dependent Ab isotypes are elevated in response to oral and i.p., but not s.c. footpad, immunization. When the T effector response to oral vaccination is examined we find that activated, adoptively transferred Ag-specific CD4(+) T cells accumulate in the draining lymph nodes, but fail to produce IFN-gamma, in MyD88(-/-) mice. Moreover, CD1d tetramer staining shows that invariant NKT cells are activated in response to oral Salmonella-OVA vaccination in wild-type, but not MyD88(-/-), mice. Treatment with neutralizing Ab to CD1d reduces the OVA-specific Ab response only in MyD88-sufficient wild-type mice, suggesting that both Ag-specific CD4 T cell and invariant NKT cell effector responses to Salmonella-OVA vaccination are MyD88 dependent. Taken together, our data indicate that the type of adaptive immune response generated to this live attenuated vaccine is regulated by both the presence of MyD88-mediated signals and vaccination route, which may have important implications for future vaccine design.

VEGF and TGF-beta are required for the maintenance of the choroid plexus and ependyma.

Although the role of vascular endothelial growth factor (VEGF) in developmental and pathological angiogenesis is well established, its function in the adult is less clear. Similarly, although transforming growth factor (TGF) beta is involved in angiogenesis, presumably by mediating capillary (endothelial cell [EC]) stability, its involvement in quiescent vasculature is virtually uninvestigated. Given the neurological findings in patients treated with VEGF-neutralizing therapy (bevacizumab) and in patients with severe preeclampsia, which is mediated by soluble VEGF receptor 1/soluble Fms-like tyrosine kinase receptor 1 and soluble endoglin, a TGF-beta signaling inhibitor, we investigated the roles of VEGF and TGF-beta in choroid plexus (CP) integrity and function in adult mice. Receptors for VEGF and TGF-beta were detected in adult CP, as well as on ependymal cells. Inhibition of VEGF led to decreased CP vascular perfusion, which was associated with fibrin deposition. Simultaneous blockade of VEGF and TGF-beta resulted in the loss of fenestrae on CP vasculature and thickening of the otherwise attenuated capillary endothelium, as well as the disappearance of ependymal cell microvilli and the development of periventricular edema. These results provide compelling evidence that both VEGF and TGF-beta are involved in the regulation of EC stability, ependymal cell function, and periventricular permeability.

Effect of vitamin B6 availability on serine hydroxymethyltransferase in MCF-7 cells.

Folate-activated one-carbon units are derived from serine through the activity of the pyridoxal-phosphate (PLP)-dependent isozymes of serine hydroxymethyltransferase (SHMT). The effect of vitamin B(6) availability on the activity and expression of the human mitochondrial and cytoplasmic SHMT isozymes was investigated in human MCF-7 cells. Cells were cultured for 6 months in vitamin B(6) replete (4.9 microM pyridoxine) minimal essential medium (alphaMEM) or vitamin B(6)-deficient medium containing 49, 4.9 or 0.49 nM pyridoxine. Total cellular PLP levels and SHMT activity were reduced 72% and 7%, respectively, when medium pyridoxine was decreased from 4.9 microM to 49 nM. Cells cultured in medium containing 4.9 nM pyridoxine exhibited 75%, 27% and 60% reduced levels of PLP, SHMT activity and S-adenosylmethionine, respectively, compared to cells cultured in alphaMEM. Cytoplasmic SHMT activity and protein levels, but not mRNA levels, were decreased in cells cultured in vitamin B(6) deficient medium, whereas mitochondrial SHMT activity and protein levels were less sensitive to vitamin B(6) availability. PLP bound to cytoplasmic SHMT with a K(d)=850 nM, a value two orders of magnitude lower than previously reported for the bovine cytoplasmic SHMT isozyme. Collectively, these data indicate that vitamin B(6) restriction decreases the activity and stability of SHMT, and that the cytoplasmic isozyme is more sensitive to vitamin B(6) deficiency than the mitochondrial isozyme in MCF-7 cells.

Prevalence of treatment choices for snoring and sleep apnea in an Australian population.

OBJECTIVES: To assess the prevalence of treatment and diagnosis of snoring and sleep apnea in the population of New South Wales Australia. METHODS: Postal survey of 10,000 people randomly selected from the electoral roll, half aged 18 to 24 and half aged 25 to 64, with telephone follow-up for some nonresponders. Weighted prevalences are reported. RESULTS: The overall response rate was 35.6% (18-24 n = 1421 and 25-64 n = 1879). One hundred and fifty-nine respondents reported seeking medical help for snoring or sleep apnea (6.3%, 95% confidence interval 5.46-7.12%), with 133 of these being aged 25 to 64. Fifty-one respondents reported subsequent treatment (2.0%; 95% CI 1.49-2.43), with some reporting more than 1 treatment. Continuous positive airway pressure was received in 17 cases, mandibular advancement splints in 9 cases, and upper airway or nasal surgery in 31 cases. Eighty-six reported receiving an overnight sleep study (polysomnography). Most surgical patients did not report having their sleep measured with a sleep study (22/31). CONCLUSIONS: The population of New South Wales has had the longest potential exposure to continuous positive airway pressure. However, few of those in even the middle-aged group reported ever being recommended continuous positive airway pressure treatment. It is more common to have a surgical intervention for snoring or sleep apnea. Surprisingly, most surgical patients do not report any associated sleep study to quantify their snoring or sleep apnea or measure the efficacy of surgery. Since a substantial proportion of patients who experience snoring and sleep apnea are not assessed via a sleep study, it is necessary to increase awareness of undergoing such clinical procedures.