Paediatric Crohn disease patients with stricturing behaviour exhibit ileal granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibody production and reduced neutrophil bacterial killing and GM-CSF bioactivity.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibodies are associated with stricturing behaviour in Crohn disease (CD). We hypothesized that CD ileal lamina propria mononuclear cells (LPMC) would produce GM-CSF autoantibodies and peripheral blood (PB) samples would contain GM-CSF neutralizing capacity (NC). Paediatric CD and control PBMC and ileal biopsies or LPMC were isolated and cultured and GM-CSF, immunoglobulin (Ig)G and GM-CSF autoantibodies production were measured by enzyme-linked immunosorbent assay (ELISA). Basal and GM-CSF-primed neutrophil bacterial killing and signal transducer and activator of transcription 5 (STAT5) tyrosine phosphorylation (pSTAT5) were measured by flow cytometry. GM-CSF autoantibodies were enriched within total IgG for LPMC isolated from CD ileal strictures and proximal margins compared to control ileum. Neutrophil bacterial killing was reduced in CD patients compared to controls. Within CD, neutrophil GM-CSF-dependent STAT5 activation and bacterial killing were reduced as GM-CSF autoantibodies increased. GM-CSF stimulation of pSTAT5 did not vary between controls and CD patients in washed PB granulocytes in which serum was removed. However, GM-CSF stimulation of pSTAT5 was reduced in whole PB samples from CD patients. These data were used to calculate the GM-CSF NC. CD patients with GM-CSF NC greater than 25% exhibited a fourfold higher rate of stricturing behaviour and surgery. The likelihood ratio (95% confidence interval) for stricturing behaviour for patients with elevation in both GM-CSF autoantibodies and GM-CSF NC was equal to 5 (2, 11). GM-CSF autoantibodies are produced by LPMC isolated from CD ileal resection specimens and are associated with reduced neutrophil bacterial killing. CD peripheral blood contains GM-CSF NC, which is associated with increased rates of stricturing behaviour.

Analysis of the mitochondrial DNA from patients with Wolfram (DIDMOAD) syndrome.

Wolfram or DIDMOAD (Diabetes Insipidus, Diabetes Mellitus, Optic Atrophy and Deafness) syndrome, which has long been known as an autosomal-recessive disorder, has recently been proposed to be a mitochondrial-mediated disease with either a nuclear or a mitochondrial genetic background. The phenotypic characteristics of the syndrome resemble those found in other mitochondrial (mt)DNA mediated disorders such as Leber's hereditary optic neuropathy (LHON) or maternally inherited diabetes and deafness (MIDD). Therefore, we looked for respective mtDNA alterations in blood samples from 7 patients with DIDMOAD syndrome using SSCP-analysis of PCR-amplified fragments, encompassing all mitochondrial ND and tRNA genes, followed by direct sequencing. Subsequently, we compared mtDNA variants identified in this disease group with those detected in a group of LHON patients (n = 17) and in a group of 69 healthy controls. We found that 4/7 (57%) DIDMOAD patients harbored a specific set of point mutations in tRNA and ND genes including the so-called class II or secondary LHON mutations at nucleotide positions (nps) 4216 and 4917 (haplogroup B). In contrast, LHON-patients were frequently (10/17, 59%) found in association with another cluster of mtDNA variants including the secondary LHON mutations at nps 4216 and 13708 and further mtDNA polymorphisms in ND genes (haplogroup A), overlapping with haplogroup B only by variants at nps 4216 and 11251. The frequencies of both haplogroups were significantly lower in the control group versus the respective disease groups. We propose that haplogroup B represents a susceptibility factor for DIDMOAD which, by interaction with further exogeneous or genetic factors, might increase the risk for disease.

Population genetics and disease susceptibility: characterization of central European haplogroups by mtDNA gene mutations, correlation with D loop variants and association with disease.

Mitochondrial (mt)DNA haplogroups in a German control group (n = 67) were characterized by screening mitochondrial coding regions encompassing most of the ND, tRNA and cyt b genes. We used a PCR-SSCP screening approach followed by direct sequencing of polymorphic mtDNA fragments. Five major mtDNA lineages, diverging in at least nine different haplogroups, could be defined by characteristic polymorphic sites in mitochondrial genes. Additional sequencing of two hypervariable segments (HVS-I and II) of the non-coding displacement (D) loop in all control subjects revealed that certain D loop variants were strongly correlated with lineages and haplogroups, while others represented hotspots occurring frequently in different haplogroups. The existence of identified lineages and haplogroups received support from data in the literature, obtained by use of different approaches. Subsequently, we investigated four disease groups for association with these haplogroups: (i) LHON patients (n = 55) carrying at least one of the primary/intermediate LHON mutations at nt 3460, 11778, 14484 and/or 15257; (ii) patients suffering from Wolfram or DIDMOAD syndrome (n = 8); (iii) MELAS patients (n = 9); (iv) a group of children, who died from 'sudden infant death syndrome' (SIDS) (n = 9). The distribution patterns among the haplogroups of the disease groups (LHON, DIDMOAD and SIDS) differed considerably from the control population. LHON and DIDMOAD were significantly under-represented in the most frequent German haplogroup DC, but were concentrated in a mtDNA lineage defined by polymorphisms at nt 4216 + 11251 + 16126. As this lineage diverged into two precisely defined haplogroups, LHON and DIDMOAD could be assigned to the two haplogroups separately. Strikingly, SIDS was often found in association with two rare German haplogroups. MELAS patients were equally distributed among German haplogroups and, moreover, did not reveal any accumulation of specific D loop variants. We conclude that certain European mtDNA haplogroups define a genetic susceptibility basis for various disorders.

Wolfram (DIDMOAD) syndrome and Leber hereditary optic neuropathy (LHON) are associated with distinct mitochondrial DNA haplotypes.

Because Wolfram (or DIDMOAD) syndrome is supposed to be a mitochondrial (mt)-mediated disease, we investigated a group of eight DIDMOAD patients with respect to point mutations of the mtDNA thus far described as being associated with defined mitochondrial disorders such as MELAS, MERRF, and LHON. Furthermore, to screen DIDMOAD patients for other mtDNA defects we used Southern blot analysis to detect mtDNA length mutations and rearrangements as well as PCR-SSCP and direct sequencing to screen all ND genes (complex I of the respiratory chain), the 22 tRNAs, and a part of the cyt b gene for unknown mutations. As a disease control group, 17 LHON patients (harboring one of the primary LHON mutations) were included in this study because of the overlapping clinical symptoms (optic atrophy) in both syndromes. We compared mtDNA variants identified in DIDMOAD patients with those found in LHON patients as well as in a control group consisting of 67 healthy German blood donors. In total, the control group was characterized by 29 polymorphic sites in ND and tRNA genes that define certain major Caucasian haplotypes. We found that a cluster of nucleotide exchanges at nucleotide positions (nps) 4216 and 11,251 roughly discriminates controls (12/67 controls, 18%) from the disease groups (6/8 DIDMOAD patients, 75%; 10/17 LHON patients, 59%). All 4216-positive LHON patients (10 patients) were concentrated in a haplogroup defined by additional exchanges at nps 10,398, 12,612, and 13,708 (haplogroup A), while the bulk of 4216-positive DIDMOAD patients (5 patients) were found in a distinct haplogroup consisting of nucleotide exchanges at nps 4917, 10,463, 13,368, 14,233, and 15,928. The frequencies of both haplogroups were significantly lower in the control group versus the respective disease groups. A more detailed analysis was performed by sequencing the two hypervariable regions of the non-coding D-loop region from patients and controls and corroborated the ranging in the two major haplogroups. Thus, the different clinical features of the mitochondrial disease groups investigated here corresponded to different clusters of mtDNA variants, which might act as predisposing haplotypes, increasing the risk for disease.