Oral tolerance is inefficient in neonatal mice due to a physiological vitamin A deficiency.

Increased risk of allergy during early life indicates deficient immune regulation in this period of life. To date, the cause for inefficient neonatal immune regulation has never been elucidated. We aimed to define the ontogeny of oral tolerance and to identify necessary conditions specific for this stage of life. Ovalbumin (OVA) was administered orally to mice through breast milk and efficiency of systemic tolerance to OVA was assessed in adulthood using a model of allergic airway inflammation. Oral tolerance induction was fully efficient starting third week of life. Inefficiency in neonates was a consequence of abnormal antigen transfer across the gut barrier and retinaldehyde dehydrogenase expression by mesenteric lymph node CD103(+) neonatal dendritic cells, resulting in inefficient T-cell activation. Neonates' serum retinol levels were three times lower than in adult mice, and vitamin A supplementation was sufficient to rescue neonatal defects and allow tolerance induction from birth. The establishment of oral tolerance required the differentiation of Th1 lymphocytes in both vitamin A-supplemented neonates and 3-week-old unsupplemented mice. This knowledge should guide the design of interventions for allergy prevention that are adapted to the neonatal stage of life such as vitamin A supplementation.

Oligoclonal expansions of mucosal T cells in Crohn's disease predominate in NKG2D-expressing CD4 T cells.

Crohn's disease (CD) is an inflammatory pathology of the mucosal intestine that results from uncontrolled immune response towards commensal microbes. Clonal expansions of T cells have been found in patients with CD suggesting an antigen-specific stimulation of pathogenic T cells. Here we show, using T-cell receptor repertoire analysis by real-time PCR, that oligoclonal expansions are found in both CD8+ and CD4+ T cells in the blood and intestinal mucosa of CD patients. The majority of CD4+ T-cell-expanded clones are CD4+NKG2D+ T cells. These clonal expansions were found in both inflamed and neighboring healthy tissue and were persisting during the course of the disease. The presence of these CD4+NKG2D+ T-cell clones at the macroscopically normal edge of the surgical resection might be predictive of inflammation relapse post surgery.

Cardiovascular prevention: relationships between arterial aging and chronic drug treatment.

Drugs acting on cardiovascular (CV) prevention are, by definition, interconnected with age-induced arterial changes. However, this question has been poorly investigated along long-term treatment. This goal requires a major prerequisite: to determine statistical links associating age-induced changes in arterial stiffness and wave reflections with drug classes acting on CV prevention. We studied 347 subjects where CV prevention involved hypertension, diabetes mellitus and hypercholesterolaemia; and included six drug classes: diuretics, ß-blocking agents, angiotensin II (ANGII) and calcium-channel (CCB) blockers, insulin therapy and statins. For each class, the total population was divided into two subgroups according to the presence or absence of the corresponding class. Statistical comparisons between subgroups involved brachial and central blood pressure measurements, aortic pulse wave velocity (PWV), augmentation index (AIx), used as a marker of wave reflections. Non-invasive measurements included tonometry and pulse wave analysis. Appropriate adjustments indicated among results the respective role of age, sex, mean blood pressure (MBP), standard risk factors and other confounding variables. CCB and statins did not exhibit statistical association with PWV or AIx. ß-Blocking agents were significantly linked with heart rate reduction and resulting increase in AIx and central pulse pressure (PP). Increased PWV independent of age, MBP, CV risk factors were noticed under diuretics, ANGII blockers and insulin, pointing to intrinsic modifications of the arterial wall. Treatment of CV prevention involves alterations of the arterial wall depending on drug class. ß-Blocking agents and insulin are associated with the higher increases of central PP.

Nod1 and Nod2 in innate immunity and human inflammatory disorders.

Nod (nucleotide-binding oligomerization domain) 1 and Nod2 are intracellular PRMs (pattern-recognition molecules) of the NLR (Nod-like receptor) family. These proteins are implicated in the detection of bacterial peptidoglycan and regulate pro-inflammatory pathways in response to bacteria by inducing signalling pathways such as NF-kappaB (nuclear factor kappaB) and MAPKs (mitogen-activated protein kinases). The Nod proteins act independently of the TLR (Toll-like receptor) cascade, but potently synergize with the latter to trigger innate immune responses to microbes. Most importantly, mutations in Nod2 have been shown to confer susceptibility to several chronic inflammatory disorders, including Crohn's disease, Blau syndrome and early-onset sarcoidosis, underscoring the role of Nod2 in inflammatory homoeostasis. This review summarizes the most recent findings in the field of Nod1 and Nod2 research.