Aluminum enhances inflammation and decreases mucosal healing in experimental colitis in mice.

The increasing incidence of inflammatory bowel diseases (IBDs) in developing countries has highlighted the critical role of environmental pollutants as causative factors in their pathophysiology. Despite its ubiquity and immune toxicity, the impact of aluminum in the gut is not known. This study aimed to evaluate the effects of environmentally relevant intoxication with aluminum in murine models of colitis and to explore the underlying mechanisms. Oral administration of aluminum worsened intestinal inflammation in mice with 2,4,6-trinitrobenzene sulfonic acid- and dextran sodium sulfate-induced colitis and chronic colitis in interleukin 10-negative (IL10(-/-)) mice. Aluminum increased the intensity and duration of macroscopic and histologic inflammation, colonic myeloperoxidase activity, inflammatory cytokines expression, and decreased the epithelial cell renewal compared with control animals. Under basal conditions, aluminum impaired intestinal barrier function. In vitro, aluminum induced granuloma formation and synergized with lipopolysaccharide to stimulate inflammatory cytokines expression by epithelial cells. Deleterious effects of aluminum on intestinal inflammation and mucosal repair strongly suggest that aluminum might be an environmental IBD risk factor.

Langhans giant cells from M. tuberculosis-induced human granulomas cannot mediate mycobacterial uptake.

Tuberculosis is characterized by a tight interplay between Mycobacterium tuberculosis (M. tb) and host cells within granulomas. These cellular aggregates restrain M. tb spreading but do not kill all bacilli, which persist for years. A more detailed investigation of the interaction between M. tb and granuloma cells is needed to improve our understanding of this persistence and to explain the physiopathology of tuberculosis. In the present study, a recently developed in vitro human model of tuberculous granulomas has been used to analyse the modulation of granuloma cell differentiation by M. tb, in comparison to poorly virulent mycobacteria, which do not persist. It is reported that whilst all mycobacteria species induce granuloma formation, only M. tb triggers the differentiation of granuloma macrophages into very large multinucleated giant cells (MGCs) that are unable to mediate any bacterial uptake. This loss of function is not due to cell quiescence, as MGCs still display NADPH oxidase activity, but it correlates with decreased expression of phagocytosis receptors. This phenomenon is specific for the virulent species of M. tuberculosis complex, as poorly virulent species only induce the formation of small multinucleated cells (MCs) with conserved mycobacterial uptake ability, which never reach the MGC differentiation stage. The phenotype of MGCs thus strongly resembles mature dendritic cells with a loss of microbial uptake ability, despite conserved antigen presentation. In M. tb-induced granulomas, MGCs thus seem to be devoted to the destruction of bacilli that have been ingested in previous differentiation stages, ie in macrophages and MCs.

Hypothalamo-hypophysial dysfunction after traumatic brain injury in children and adolescents: a preliminary retrospective and prospective study.

With two study protocols, one retrospective and the other prospective, we evaluated hypothalamo-hypophysial dysfunction (HHD) in paediatric patients treated for traumatic brain injury (TBI) in the neurosurgical or intensive care department at our hospital. The retrospective group comprised 22 patients who had experienced TBI 0.7-7.25 years before the study. The prospective group included 30 patients assessed at TBI (T0), 26 of 30 after 6 months (T6), and 20 of 26 after 12 months (T12). Auxological and hormonal basal parameters of hypothalamo-hypophysial function were evaluated at recall in the retrospective group, and at T0, T6 and T12 in the prospective group. Basal data and standard dynamic tests in selected patients revealed one with precocious puberty, one with total anterior hypopituitarism, one with central hypogonadism, and one with growth hormone (GH) deficiency in the retrospective group; three patients with cerebral salt-wasting syndrome, one with diabetes insipidus and seven with low T3 syndrome at T0 (all transient), one with hypocorticism at T6 confirmed at T12, and one with GH deficiency at T12 in the prospective group. The results of our study show that post-TBI HHD in our paediatric cohort is not uncommon. Of the 48 patients who underwent a complete evaluation (22 retrospective study patients and 26 prospective study patients evaluated at T6) five (10.4%) developed HHD 6 months or more after TBI. HHD was newly diagnosed in one previously normal patient from the prospective group at 12 months after TBI. GH deficiency was the most frequent disorder in our paediatric cohort.

A high neonatal serum eosinophil cationic protein level is a risk factor for atopic symptoms.

AIM: To show whether neonatal eosinophil counts (EC) and eosinophil cationic protein (ECP) can be used in assessing the risk of atopy, alone or in combination with family history of atopy (FHa). PATIENTS AND METHODS: A group of 63 newborns was included: 38 with FHa, 25 without FHa. A blood sample was collected on the 4th day of life for EC and ECP evaluation. Clinical follow-up was conducted after 1, 3, 6, 12, 18, 24 and 36 mo. The chi2 test and the Student's t-test were used to compare dichotomic and continuous variables, respectively. Variables shown to be significant by univariate analysis were evaluated with a multivariate regression model and the relative risks (RR) were estimated. RESULTS: Twenty-six newborns (41%) displayed atopic manifestations during the follow-up. Twenty-one (55%) of 38 newborns with FHa displayed atopic symptoms versus 5/25 (20%) without FHa (p 0.012). Neither EC nor serum ECP levels were significantly different between newborns with FHa and newborns without. ECP levels did not differ between newborns with single heredity and newborns with dual heredity. EC did not differ significantly between newborns who developed atopy and those who did not. Instead, serum ECP levels were significantly higher in newborns who developed atopy (mean 27.9 microU/l vs 16.8 microU/l). Atopic manifestations appeared in 16 (62%) of 26 newborns with ECP > or = 18 microU/l compared with 10 (27%) of 37 with ECP < 18 microU/l (p = 0.006). In the multivariate regression model, with ECP < 18 microU/l and no FHa as reference class, the class 1 (no FHa and ECP > or = 18 microU/l) has a low RR (1.4), class 2 (FHa and ECP < 18 microU/l) an intermediate RR (2.7) and class 3 (FHa and ECP > or = 18 microU/l) a very high RR (16.3). CONCLUSIONS: Neonatal serum ECP levels, in contrast with EC, were significantly higher in newborns who developed atopic manifestations during follow-up. The risk of atopy was about twice as great when ECP was > or = 18 microU/l (and four times as great in multivariate analysis). When serum ECP was combined with FHa, the RR for newborns with FHa and ECP > or = 18 microU/l was 16 times greater than for those without FHa and ECP < 18 microU/l. The identification of newborns at "extremely high atopic risk" (FHa and ECP > or = 18 microU/l) may be expecially useful--in clinical practice--in newborns with only one atopic parent or sibling, for whom it is not universally agreed that dietary and environmental prevention measures should be applied.

Pamidronate treatment in bone fibrous dysplasia in children and adolescents with McCune-Albright syndrome.

Thirteen patients with McCune-Albright syndrome (MAS) and bone fibrous dysplasia (BFD) have been treated for 2-6 years with pamidronate, an aminobisphosphonate which inhibits osteoclastic function. MAS is a rare genetic condition caused by constitutive activating mutations of the Gs protein and manifests with skin dysplasia, bone fibrous dysplasia, and multiple endocrinopathies. Raised serum alkaline phosphatase and urinary hydroxyproline have been reported in these patients, indicating bone metabolic hyperactivity. Encouraging therapeutic results have been achieved with pamidronate, mainly in adults. In our study, treatment reduced bone pain, fracture rate and metabolic indices of bone turnover, in particular significantly decreased bone alkaline phosphatase and cross-links (Wilcoxon test; p <0.06), and increased bone mineral density (DEXA). Signs of healing, such as thickening of the cortical bone, were found in some patients. Three patterns of MRI were found: homogeneous hypointense fibrous tissue, 'dotted' hypointense fibrous tissue, and hyperintense cystic images. Pamidronate treatment can be considered a favorable therapeutic option for patients with MAS.

Thyroid diseases in patients treated during pre-puberty for medulloblastoma with different radiotherapic protocols.

We evaluated thyroid disease in 32 patients treated, during pre-puberty, for medulloblastoma, followed for at least 4 years and without relapse during observation. After surgery the patients underwent chemotherapy (CT) and radiotherapy (RT). The protocols were as follows: 20 patients (group A) SNC 76 and SNC 85 protocols which included conventional fractionated RT (36-40 Gy to the craniospinal axis and a 14-18 Gy boost to the posterior fossa, administered as 1.5-1.8 Gy per fraction per day) and a junction between the cranial and the spinal fields at C2-C3 level; 12 patients (group B) SNC 91 protocol which included hyperfractionated RT (36 Gy to the craniospinal axis and a 30 Gy boost to the posterior fossa; this was administred as 1 Gy per fraction twice per day) and a junction at levels C5-C6 or C6-C7 level. The mean age at diagnosis was 7.4+/-3.2 years for group A and 8.4+/-2.6 years for group B. Thyroid function was evaluated yearly and ultrasonographic characteristics every 2 years. The patients were followed for a mean of 10.8+/-3.8 for group A and 6+/-1.4 years for group B. Primary hypothyroidism was diagnosed in 16 group A patients and 4 group B patients, and central hypothyroidism was diagnosed in 2 group A patients (difference in risk of developing hypothyroidism evaluated with a Wilcoxon-test: p=0.048). Ultrasonography showed reduced thyroid volume in 7 group A cases, and structural changes in 21 patients (17 group A, 4 group B); 9 L-thyroxine-treated patients were confirmed hypothyroid after having stopped therapy. A thyroid nodule was detected in two cases (one from each group). In conclusion, our data indicate that thyroid injury may be diminished by the use of hyperfractionation and low-junction radiotherapy in the treatment of medulloblastoma.

Interleukin-12 receptor beta1 deficiency in a patient with abdominal tuberculosis.

Two siblings with interleukin-12 receptor beta1 (IL-12Rbeta1) deficiency but different clinical phenotypes were studied. Both are homozygous for an IL12RB1 missense mutation that prevents receptor expression and abolishes cellular responses to IL-12. Transfection of the patients' T cells with wild-type IL12RB1 restored IL-12Rbeta1 expression and function. One patient had the expected phenotype of disseminated bacille Calmette-Guérin (BCG) infection in early childhood, whereas the other did not develop BCG infection, despite 3 inoculations with live BCG. Abdominal tuberculosis was diagnosed in this second patient at age 18 years. To date, neither of them has had clinical disease caused by environmental mycobacteria. These observations show unexpected interfamilial and intrafamilial heterogeneity of the clinical phenotype associated with IL-12Rbeta1 deficiency. The patients may be resistant to BCG but remain vulnerable to Mycobacterium tuberculosis. A diagnosis of IL-12Rbeta1 deficiency should therefore be considered in selected patients with severe tuberculosis, despite their resistance to BCG and a lack of atypical mycobacteriosis.

Mycobacterium fortuitum-chelonae complex infection in a child with complete interleukin-12 receptor beta 1 deficiency.

A 10-year-old boy had chronic diarrhea, abdominal pain, severe weight loss and hepatomegaly; multiple enlarged para-aortic and mesenteric lymph nodes. Mycobacterium fortuitum-chelonae complex was identified in the culture of the lymph nodes. Interleukin-12 receptor beta 1 expression could not be observed in phytohemagglutinin-driven T cell blasts. A homozygous missense interleukin-12 receptor beta 1 mutation was found (R173P).

Genetic heterogeneity of Mendelian susceptibility to mycobacterial infection.

Mendelian susceptibility to poorly virulent mycobacterial species, such as bacillus Calmette-Guérin (BCG) and environmental nontuberculous mycobacteria (NTM), is a phenotypically heterogeneous syndrome. It has therefore long been suspected to be genetically heterogeneous. In the past 5 years, this prediction has been confirmed and different types of mutations (dominant or recessive, nonfunctional or hypofunctional) in four genes (IFNGR1, IFNGR2, IL12B, IL12RB1) have revealed both allelic and nonallelic heterogeneity. The eight disorders resulting from these mutations are genetically different but immunologically related, as impaired IFN-gamma-mediated immunity is the common pathogenic mechanism accounting for mycobacterial infection in all patients. The severity of the phenotype depends on the genotype. Complete IFN-gammaR1 and IFN-gammaR2 deficiencies predispose patients to a more severe clinical course than partial IFN-gammaR1 and IFN-gammaR2 deficiencies and complete IL-12 p40 and IL-12Rbeta1 deficiencies.

Impairment of STAT activation by IL-12 in a patient with atypical mycobacterial and staphylococcal infections.

IL-12 plays a pivotal role in the stimulation of immune responses against intracellular infections. This role is manifested in the increased susceptibility to atypical mycobacterial and salmonella infections among individuals whose lymphocytes lack expression of IL-12Rbeta1. Here, we report on a patient with Mycobacterium avium infection, recurrent Staphylococcus aureus sinusitis, and multiple adverse drug reactions whose T cells were unable to produce IFN-gamma or proliferate in response to IL-12 despite the expression of wild-type IL-12Rbeta1 and IL-12Rbeta2. The defect in these functional responses to IL-12 was selective, as cytolytic activity induced by IL-12 was intact, and lymphocytes were responsive to stimulation by IL-2. An examination of cytokine signaling revealed that STAT4 and extracellular regulated kinase 1 (ERK1) activation by IL-12 was intact, whereas the activation of STAT1, -3, and -5 by IL-12 was lost. This impairment of STAT activation was specific for IL-12, as STAT activation by IL-2, IL-15, and IFN-gamma was unaffected. These findings demonstrate that the activation of STAT4 alone is not sufficient for IL-12-induced IFN-gamma production and proliferation and suggest that other STATs play a role in these responses to IL-12. While the etiology of the impaired IL-12 signaling in this patient has not yet been elucidated, the absence of mutations in IL-12Rbeta1 or IL-12Rbeta2 and the preservation of STAT4 activation raise the possibility that there may be a mutation in an as yet undiscovered component of the IL-12 signaling complex that is normally required for the recruitment and activation of STAT1, -3, and -5.

In a novel form of IFN-gamma receptor 1 deficiency, cell surface receptors fail to bind IFN-gamma.

Complete IFN-gamma receptor ligand-binding chain (IFNgammaR1) deficiency is a life-threatening autosomal recessive immune disorder. Affected children invariably die of mycobacterial infection, unless bone marrow transplantation is undertaken. Pathogenic IFNGR1 mutations identified to date include nonsense and splice mutations and frameshift deletions and insertions. All result in a premature stop codon upstream from the segment encoding the transmembrane domain, precluding cell surface expression of the receptors. We report herein two sporadic and two familial cases of a novel form of complete IFNgammaR1 deficiency in which normal numbers of receptors are detected at the cell surface. Two in-frame deletions and two missense IFNGR1 mutations were identified in the segment encoding the extracellular ligand-binding domain of the receptor. Eight independent IFNgammaR1-specific mAb's, including seven blocking antibodies, gave recognition patterns that differed between patients, suggesting that different epitopes were altered by the mutations. No specific binding of (125)I-IFN-gamma to cells was observed in any patient, however, and the cells failed to respond to IFN-gamma. The mutations therefore cause complete IFNgammaR1 deficiency by disrupting the IFN-gamma-binding site without affecting surface expression. The detection of surface IFNgammaR1 molecules by specific antibodies, including blocking antibodies, does not exclude a diagnosis of complete IFNgammaR1 deficiency.

Partial interferon-gamma receptor signaling chain deficiency in a patient with bacille Calmette-Guérin and Mycobacterium abscessus infection.

Complete deficiency of either of the two human interferon (IFN)-gamma receptor components, the ligand-binding IFN-gammaR1 chain and the signaling IFN-gammaR2 chain, is invariably associated with early-onset infection caused by bacille Calmette-Guérin vaccines and/or environmental nontuberculous mycobacteria, poor granuloma formation, and a fatal outcome in childhood. Partial IFN-gammaR1 deficiency is associated with a milder histopathologic and clinical phenotype. Cells from a 20-year-old healthy person with a history of curable infections due to bacille Calmette-Guérin and Mycobacterium abscessus and mature granulomas in childhood were investigated. There was a homozygous nucleotide substitution in IFNGR2, causing an amino acid substitution in the extracellular region of the encoded receptor. Cell surface IFN-gammaR2 were detected by flow cytometry. Cellular responses to IFN-gamma were impaired but not abolished. Transfection with the wild-type IFNGR2 gene restored full responsiveness to IFN-gamma. This is the first demonstration of partial IFN-gammaR2 deficiency in humans.

Human interferon-gamma-mediated immunity is a genetically controlled continuous trait that determines the outcome of mycobacterial invasion.

Individuals with inherited disorders of interferon gamma (IFN-gamma)-mediated immunity appear to be specifically vulnerable to mycobacterial infections. The severity of clinical features of affected individuals differs between cases. Some patients die of mycobacterial infection in early childhood, whereas others have long asymptomatic periods in childhood and as adults. This rare syndrome also shows high allelic and non-allelic genetic heterogeneity. Mutations in IL12B, encoding the interleukin (IL)-12 p40 subunit, and in IL12RB1, encoding the beta1 chain of the IL-12 receptor, result in impaired IFN-gamma production. Mutations in IFNGR1 and IFNGR2, encoding the two IFN-gamma receptor chains, and mutations in STAT1, encoding an essential signaling component, result in impaired cellular responses to IFN gamma. Different types of mutation define two types of complete and two types of partial IFNgammaR1 deficiency. Complete and partial IFNgammaR2 deficiency have also been described. We herein compare the genotypes, cellular phenotypes, and clinical phenotypes of healthy individuals and patients with the seven known genetic disorders impairing cellular responses to IFN-gamma. Patients with defective IFN-gamma production were not considered in this study. The mutations and clinical features of patients with IFNgammaR1, IFNgammaR2, and STAT-1 deficiency are reviewed. Selected cell lines from each of the eight groups were tested for their response to IFN-gamma. We find that individuals may be classified into four broad groups based on genotype, cellular phenotype, and clinical phenotype (normal individuals and patients with mild, intermediate, or severe disease). This correlation suggests that IFN-gamma-mediated cell activation is a genetically controlled quantitative trait and that it determines the outcome of mycobacterial invasion in man.

IL-12 and IFN-gamma in host defense against mycobacteria and salmonella in mice and men.

The development of gene-knockout mice and the identification of gene-deficient humans have improved our understanding of the role of IL-12 and IFN-gamma in host defense. Comparison of experimental and natural infections has shown that animals and humans genetically deficient in immunity mediated by IL-12 or IFN-gamma are highly susceptible to mycobacteria and salmonella. Impaired secretion of, or response to, IFN-gamma is the common pathogenic mechanism that accounts for impaired granuloma formation and uncontrolled growth of bacteria within macrophages. The axis formed between IL-12 and IFN-gamma is essential for protective immunity against mycobacteria and salmonella in mice and men.

A human IFNGR1 small deletion hotspot associated with dominant susceptibility to mycobacterial infection.

The immunogenetic basis of severe infections caused by bacille Calmette-Guérin vaccine and environmental mycobacteria in humans remains largely unknown. We describe 18 patients from several generations of 12 unrelated families who were heterozygous for 1 to 5 overlapping IFNGR1 frameshift small deletions and a wild-type IFNGR1 allele. There were 12 independent mutation events at a single mutation site, defining a small deletion hotspot. Neighbouring sequence analysis favours a small deletion model of slipped mispairing events during replication. The mutant alleles encode cell-surface IFNgamma receptors that lack the intra-cytoplasmic domain, which, through a combination of impaired recycling, abrogated signalling and normal binding to IFNgamma exert a dominant-negative effect. We thus report a hotspot for human IFNGR1 small deletions that confer dominant susceptibility to infections caused by poorly virulent mycobacteria.

Inherited interleukin 12 deficiency in a child with bacille Calmette-Guérin and Salmonella enteritidis disseminated infection.

Interferon-gamma receptor ligand-binding chain (IFN-gammaR1) or signaling chain (IFN-gammaR2) deficiency, like interleukin 12 receptor beta1 chain (IL-12Rbeta1) deficiency, predispose to severe infections due to poorly virulent mycobacteria and salmonella. A child with bacille Calmette-Guérin and Salmonella enteritidis infection was investigated. Mutations in the genes for IFN-gammaR1, IFN-gammaR2, IL-12Rbeta1, and other molecules implicated in IL-12- or IFN-gamma-mediated immunity were sought. A large homozygous deletion within the IL-12 p40 subunit gene was found, precluding expression of functional IL-12 p70 cytokine by activated dendritic cells and phagocytes. As a result, IFN-gamma production by lymphocytes was markedly impaired. This is the first discovered human disease resulting from a cytokine gene defect. It suggests that IL-12 is essential to and appears specific for protective immunity to intracellular bacteria such as mycobacteria and salmonella.

Interferon-gamma receptor deficiency: relationship between genotype, environment, and phenotype (Review).

Interferon-gamma receptor ligand binding chain (IFNgammaR1) deficiency is an autosomal recessive inherited immune disorder. Mutations in the IFNgR1 gene are associated with severe infections due to mycobacteria. However, several aspects of the phenotype of IFNgammaR1-deficient children have recently been found to vary from case to case. This review thus discusses the respective roles of the genotype and of the environment in determining phenotypic variations among affected children.

Mendelian susceptibility to mycobacterial infection in man.

Selective susceptibility to poorly pathogenic mycobacteria, such as bacille Calmette-Guérin vaccine and environmental non-tuberculous mycobacteria, has long been suspected to be a mendelian disorder but its molecular basis has remained elusive. Recently, recessive mutations in the interferon-gamma-receptor receptor ligand-binding chain, interferon-gamma-receptor signalling chain, IL-12 p40 subunit and IL-12-receptor beta 1 chain genes have been identified in a number of patients with disseminated mycobacterial infection. Although genetically distinct, these conditions are immunologically related and highlight the essential role of interferon-gamma-mediated immunity in the control of mycobacteria in man.