Alterations in innate and adaptive immune leukocytes are involved in paediatric obesity

BACKGROUND

Adipose tissue is the main source of the cytokines and adipokines that are increased in the context of obesity. The production of reactive oxygen species (ROS) and cytokines by circulating immune cells can be regulated by these pro-inflammatory factors even before infiltration into adipose tissue.

OBJECTIVE

To investigate the alterations that can occur in circulating monocytes and lymphocytes in paediatric obesity.

METHODS

In this study, 54 paediatric obese patients and 30 age-matched metabolically healthy individuals were enrolled. Intracellular cytokines were analyzed after phorbol myristate acetate (PMA) or leptin plus PMA stimulation of lymphocytes and monocytes by flow cytometry. ROS generation was measured using dichlorofluorescein-diacetate. Both a 'stimulation index' and a 'fold of increase' were calculated for statistical purposes.

RESULTS

Both interferon gamma (IFN-γ) production by circulating CD4+ and CD8+ lymphocytes and ROS production by monocytes following PMA stimulation were increased in obese patients. Leptin induced an increased production of IFN-γ in both subsets of T cells and tumour necrosis factor alpha in monocytes, and linoleic acid induced a higher ROS production in monocytes.

CONCLUSIONS

The distinct functional responses of circulating cells suggest that alterations in both innate and adaptive immune cells are involved in the maintenance of low-grade inflammation in paediatric obesity.

IL-15 controls T cell functions through its influence on CD30 and OX40 antigens in Celiac Disease

AIM

To evaluate the ability of interleukin (IL)-15 to control T cell functions through its influence on CD30 and OX40 expressing cells in Celiac Disease (CD). In peripheral blood (PB), by examining the expression of OX40 in conventional effectors cells and T cells with a phenotypic specialization of regulatory cells [CD4+CD25high forkhead box protein 3 (Foxp3)+], and the co stimulation of IFN-γ and IL-4 production within CD30 and OX40 positive subsets of T cells. At the duodenal mucosa, by assessing the expression of CD30 and OX40 in intraepithelial (IE) and lamina propria (LP) lymphocytes (IEL, LPL).

PATIENTS AND METHODS

PB and duodenal mucosal biopsies were obtained from 38 patients with classic CD (Cel) and 38 healthy controls (HC). Analysis of cell surface and/or intracellular antigens was performed in anti-CD3-treated PB mononuclear cells (PBMC) before and after treatment with recombinant IL-15 (rIL-15), and in IE and LP cellular suspensions prepared from duodenal biopsies pre-treated with/without rIL-15.

RESULTS

A subpopulation of CD3+OX40+ T blasts was induced in Cel and HC by a 3days treatment of PBMC with anti-CD3 and decreased its size thereafter, regardless of the presence of rIL-15. However, the addition of rIL-15 to T blasts distinctively induced the survival of T cells with a regulatory phenotype that expresses OX40 antigen in Cel (p<0.05). Celiac patients showed higher frequencies of IFN-γ-producing CD3+CD30+ blasts before and after treatment with rIL-15 (p<0.05, vs. HC). IL-15 increased the frequencies of CD3+CD30+ LPL (HC: p<0.05, Cel: p<0.05) but not of CD3+OX40+ LPL, and CD30 or OX40 positive IEL.

CONCLUSIONS

The distinctive control of OX40+ cells with a T regulatory phenotype mediated by the influence of IL-15 comes out as new function of this cytokine in the context of CD. The higher production of IFN-γ by a subpopulation of peripheral CD3+CD30+ cells contributes to the type I biased immune response.

Liver infiltrating mononuclear cells in children with type 1 autoimmune hepatitis

OBJECTIVE

To investigate infiltrating cells in the liver of children with type 1 autoimmune hepatitis (AH-1).

METHODS

liver biopsies from 24 untreated AH-1 patients (14 children, 10 adults), five patients with hepatitis C virus related chronic hepatitis (HCV), and 10 control liver specimens (CL) were processed for immunohistochemical cell characterisation.

RESULTS

Two different cell distribution patterns were detected in the liver of patients with AH-1: (1) CD4(+) and CD20(+) cells were found in the central areas of the portal tracts (portal distribution); (2) CD8(+) cells were observed at the periphery of the portal space (periportal distribution). Some cell subsets, like CD56, CD57, Fas-L, and Bak, showed a non-defined distribution pattern. The presence of two well defined patterns of cell distribution was not observed in HCV and CL (CD4(+), CD20(+), and CD8(+) cells were uniformly distributed in the portal space). In AH-1 and CL, the NK markers CD56 and CD57 were found scattered throughout the liver parenchyma. However, in HCV biopsies, CD56(+) cells were also clearly increased in both the portal and the periportal areas. Biopsies of AH-1 and HCV patients showed a uniform distribution of Fas-L and Bak in the portal and periportal areas, with Bak staining also detected in the hepatic parenchyma.

CONCLUSIONS

Despite clinical and genetic differences, there was a similar distribution of liver infiltrating mononuclear cells in children and adults with AH-1. These results raise the possibility of reclassifying cryptogenic chronic hepatitis by immunohistochemical analysis of infiltrating liver cells.

N-formyl-methionyl-leucyl-phenylalanine (fMLP) inhibits tumour necrosis factor-alpha (TNF-alpha) production on lipopolysaccharide (LPS)-stimulated human neutrophils

During gram-negative infections bacterial components, such as LPS and formylated peptides, exert profound physiological effects on polymorphonuclear neutrophils (PMN) resulting in increased neutrophil effector activities, including the generation of oxidative metabolites, degranulation, phagocytosis and cytokine release. There is not enough evidence about the relationships between LPS and formylated bacterial peptides in the triggering and regulation of the immune inflammatory response. In this study, we present evidence indicating that pretreatment of human PMN with a prototype formylated peptide such as fMLP results in the inhibition of TNF-alpha secretion, a key molecule that plays a central role in the pathogenesis of septic shock. This inhibitory effect of fMLP does not appear to alter the expression of LPS receptors or the transcriptional pathway of the TNF-alpha mRNA, but instead, fMLP reduces the expression of the membrane form of TNF-alpha on the PMN surface. These findings indicate that fMLP, a typical proinflammatory agent, could play, at least in determined conditions, an anti-inflammatory role.

Haloperidol and oestrogens induce c-myc and c-fos expression in the anterior pituitary gland of the rat

Decreased dopaminergic and increased oestrogenic effects induce prolactin release and DNA synthesis in prolactin secreting cells of the adult male rats. Oestrogen treatment for 7 days significantly increased the levels of prolactin, c-myc and c-fos mRNAs. The effect of oestrogens was reversed by the administration of the dopaminergic agonist bromocriptine. There was an early gradual increase of c-myc mRNA levels beginning 30 min after the injection of the steroid. c-fos mRNA levels increased sharply 15 min after oestrogen administration and decreased to basal values 15 min later to remain at this level over the period of time evaluated. Administration of the dopaminergic antagonist haloperidol did not change the levels of protooncogenes mRNA. However, in rats previously treated with oestrogens for 7 days c-myc mRNA levels increased 90 min after the injection of haloperidol and decreased to basal values after 2.5 h. c-fos mRNA levels increased sharply 30 min after haloperidol administration and also decreased to basal values 1 h later. We propose that changes in protooncogenes expression may be involved in the stimulation of cell proliferation induced by prolactin secretion.

Human pituitary tumours: studies on genes expression

Searching for differences in gene expression between different types of human pituitary adenomas, we evaluated the concentration of mRNA from hormonal genes (prolactin and growth hormone) and oncogenes (c-myc and c-fos) in 12 growth hormone-secreting 7 prolactin-secreting and 11 nonsecreting adenomas. We found a positive correlation between clinical diagnoses and hormonal gene expression in all the cases. Our reports indicate the presence of c-myc and c-fos mRNA in all the adenomas evaluated. The concentration of c-myc mRNA was higher in somatotrophic adenomas than in prolactinomas and nonsecreting adenomas whereas c-fos mRNA concentration was similar in the different types of tumours analysed. Oncogenes products, in turn, might stimulate DNA synthesis and cell proliferation and eventually lead to the formation of pituitary adenomas. This is a working hypothesis.

Indomethacin inhibits the effects of oestrogen in the anterior pituitary gland of the rat

Two inhibitors of prostaglandin synthesis, indomethacin and aspirin, blocked the increase of oestrogen-binding sites in the nuclear subcellular fraction, an increase which occurs after the administration of oestradiol. Consequently the biological effects of oestrogens in the anterior pituitary gland of the rat (prolactin synthesis, concentration of progesterone-binding sites and cell proliferation) are diminished. The anterior pituitary gland synthesized prostaglandin F2 alpha (PGF2 alpha), PGE2 and PGD2 from arachidonic acid. This synthesis was blocked when indomethacin was added to the culture media. Oestrogen increased the concentration of PGE2: an increase that was partially prevented by indomethacin. Prostaglandins may have an important role on the effects of oestrogen in the anterior pituitary gland of the rat.