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Biomedical subjects

M Mäki

Publications and source records attributed to M Mäki.

At least 37 records · Page 2Linked to original sources
PubMed2003

Additional factor in some HLA DR3/DQ2 haplotypes confers a fourfold increased genetic risk of celiac disease.

Although HLA-DQ genes are the major celiac disease (CD) susceptibility genes, results from Finnish families suggest that not all DQ2-encoding haplotypes confer equal susceptibility to CD, implying the effect of other gene(s) in the HLA region. The aim of the present work was to extend and confirm the aforementioned results in a southern European population ( Italian) and to better localize the additional risk factor/s. The association of nine loci spanning the HLA region from DR to HFE, 4.5-Mb telomeric of HLA-A, was tested. The analysis was performed by comparing marker frequencies in DR3-DQ2 haplotypes transmitted and non-transmitted to the affected offspring in 156 Italian CD families selected for having at least one DR3-positive parent. The same analysis was performed independently in 101 Finnish CD families selected with the same criteria. Three alleles, MICA-A5.1, MICB-CA24 and MIB-350, all characteristic of the B8-DR3 extended haplotype, showed a significantly increased frequency in DR3 transmitted haplotypes in the Italian families. DR3 haplotypes carrying the combination of these alleles conferred an approximate fourfold increased CD risk. B8-DR3 transmitted haplotypes were significantly more conserved telomerically down to the MIC-Class I region. Similar results were seen in the Finnish families. The major conclusion that holds true in both populations is that, while DQ2 is an absolute requirement for the development of CD, the presence of an additional genetic factor within the MIC-Class I region confers an approximate 4-fold increased risk of the disease.

Celiac Disease↗
PubMed2003

Elevation of IgG antibodies against tissue transglutaminase as a diagnostic tool for coeliac disease in selective IgA deficiency.

BACKGROUND: IgA serum autoantibodies against tissue transglutaminase (tTG) have an established diagnostic value in coeliac disease, and high efficacy tests are widely available for their detection. However, serological evaluation of IgA deficient subjects is still difficult. AIMS: To evaluate the diagnostic potential of IgG class anti-tTG autoantibodies measured quantitatively using an enzyme linked immunosorbent assay (ELISA) compared with immunofluorescent detection of coeliac autoantibodies. PATIENTS: We tested serum samples from 325 IgA deficient subjects, including 78 patients with coeliac disease, 73 disease controls, and 174 blood donors. METHODS: IgG antibodies against human recombinant tTG were measured with an ELISA. IgG antiendomysium antibodies (EMA) were assayed by indirect immunofluorescence on human jejunum and appendix sections. RESULTS: The IgG anti-tTG ELISA had a sensitivity of 98.7% and a specificity of 98.6%, and the correlation with IgG EMA titres was high (r(s)=0.91). One coeliac patient, initially negative in all autoantibody tests, displayed both IgG anti-tTG antibodies and IgG EMA during later gluten exposure. IgG anti-tTG antibodies and EMA titres showed significant decreases (p<0.001) in treated patients. The frequency of IgG anti-tTG autoantibody positivity was 9.8% among IgA deficient blood donors and 11 of the 12 positive subjects with known HLA-DQ haplotypes carried DQ2 or DQ8 alleles. CONCLUSIONS: IgG anti-tTG and IgG EMA autoantibody tests are highly efficient in detecting coeliac disease in IgA deficient patients. The high prevalence of coeliac antibodies among symptom free IgA deficient blood donors who also carry coeliac-type HLA-DQ genes indicates that all IgA deficient persons should be evaluated for coeliac disease.

Autoantibodies↗
PubMed2003

Missing endomysial and reticulin binding of coeliac antibodies in transglutaminase 2 knockout tissues.

BACKGROUND: Autoantibodies against transglutaminase 2 (TG2) are thought to be responsible for the endomysial (EMA), reticulin (ARA), and jejunal antibody (JEA) tissue binding of serum samples from coeliac patients but the exclusive role of TG2 in these staining patterns has not yet been established. AIMS: To evaluate whether antigens other than TG2 contribute to EMA/ARA/JEA reactions. PATIENTS: Serum samples from 61 EMA/ARA/JEA positive untreated patients with coeliac disease, 40 dermatitis herpetiformis patients, and 34 EMA/ARA/JEA negative non-coeliac controls were tested. METHODS: TG2 knockout (TG2-/-) and wild-type mouse oesophagus, jejunum, liver, and kidney sections, and TG2-/- sections coated with human recombinant TG2 were used as substrates in single and double immunofluorescent studies for patient IgA binding and tissue localisation of TG2, fibronectin, actin, and calreticulin. RESULTS: None of the patient serum samples elicited EMA, ARA, or JEA binding in TG2-/- morphologically normal tissues. In contrast, 96 of 101 gluten sensitive patient samples (95%) reacted with wild-type mouse tissues and all 101 reacted in EMA/ARA/JEA patterns with TG2-/- mouse tissues coated with human TG2. Serum IgA binding to TG2-/- smooth muscle cells was observed in low titres in 31.1%, 27.5%, and 20.5%, and to TG2-/- epithelium in 26.3%, 5.0%, and 8.8% of coeliac, dermatitis herpetiformis, and control samples, respectively. These positivities partly colocalised with actin and calreticulin but not with TG2 or fibronectin. CONCLUSIONS: EMA/ARA/JEA antibody binding patterns are exclusively TG2 dependent both in coeliac and dermatitis herpetiformis patients. Actin antibodies are responsible for some positivities which are not part of the EMA/ARA/JEA reactions.

Adolescent↗
PubMed2002

Genetic dissection between silent and clinically diagnosed symptomatic forms of coeliac disease in multiplex families.

BACKGROUND: Coeliac disease has a large variation in clinical outcome. In addition to the classical disease with malabsorption, many individuals have a silent form, in which subject symptoms are missing but autoantibodies and mucosa lesions are identical to the symptomatic disease. AIM: To investigate whether differences in HLA DR-DQ genes explain the variation in outcome. MATERIALS AND METHODS: HLA DQ alleles were determined in 28 multiplex families with sibling pairs in which one had the symptomatic disease but the other had the silent form. RESULTS: No differences in the distribution of HLA DR-DQ haplotypes could be observed. The clinically diagnosed coeliac disease seemed to have earlier onset than silent coeliac disease. CONCLUSIONS: Results indicate that the major genetic susceptibility locus, HLA DQ, does not determine the exact clinical outcome of coeliac disease.

Alleles↗
PubMed2002

Genetic dissection between coeliac disease and dermatitis herpetiformis in sib pairs.

Gluten sensitive enteropathy has various manifestations, of which the two major forms are classical coeliac disease (cCD) and dermatitis herpetiformis (DH). In cCD predominantly the small intestine is affected, whereas in DH also the skin is affected showing typical rash and IgA deposits. The symptoms in both forms are dependent on gluten intake. The factors diversifying these two clinical outcomes are unknown. In the present report we evaluated the role of the major genetic susceptibility locus, HLA DQ, in 25 families, in which both forms of the disease, cCD and DH, occurred in siblings. By using the family-based approach it can be assumed that within each family variation in environmental factors is substantially lower than in the standard case-control setting, and also the problems related to population stratification can be avoided. Results from the Finnish family material with 25 discordant and 85 concordant sib pairs, and from additional case-control material comprising 71 unrelated Hungarian DH and 68 cCD patients, together indicated that the HLA DQ locus did not differ between the two major outcomes of gluten sensitive enteropathy. The non-HLA DR;DQ factors are critical for the different clinical manifestations of gluten sensitivity.

Case-Control Studies↗
PubMed2002

CD80 (B7-1) and CD86 (B7-2) genes and genetic susceptibility to coeliac disease.

The role of the costimulatory molecules B7-1 (CD80) and B7-2 (CD86) in T-cell activation makes them good candidates for coeliac disease susceptibility genes. We conducted a genetic linkage study of the CD80/86 gene region in the general Finnish population and in a local subisolate. No linkage was found in either population.

Antigens, CD↗
PubMed2002

Not all HLA DR3 DQ2 haplotypes confer equal susceptibility to coeliac disease: transmission analysis in families.

BACKGROUND: HLA-DQ is the only established susceptibility factor for coeliac disease. We tested whether all HLA haplotypes with the known risk marker, HLA-DQ2, confer equal susceptibility to coeliac disease, i.e. whether haplotype transmission from DQ2 homozygous parents to patients is random. The random transmission would strengthen the importance of DQ2 as the only risk factor within the HLA region. METHODS: Inheritance of DQ2-positive haplotypes from parent to patients was investigated in 14 of 127 Finnish coeliac families who had an HLA-DQ2 homozygous parent. HLA alleles and 18 HLA-linked microsatellite markers were used to determine the haplotypes, which were divided into those transmitted and those non-transmitted from DQ2-homozygous parents to patients: RESULTS: Transmitted haplotypes differed clearly from those not transmitted. The alleles in the transmitted haplotypes were strongly conserved and predominantly consisted of the well-known HLA-A*01, B*08, DRB1*03, DQ2, DPB1*0101 haplotype. The non-transmitted haplotypes, on the other hand, were significantly more heterogeneous; in particular, markers near HLA-A and -B genes differed from the transmitted haplotypes. CONCLUSIONS: The results suggest that DQ2 is not the only HLA-linked genetic risk factor for coeliac disease but the conserved haplotype harbours at least one other risk gene.

Adult↗
PubMed2002

Coeliac disease among healthy members of multiple case coeliac disease families.

BACKGROUND: The main objective of the study was to assess the frequency of undetected coeliac disease among the first-degree relatives of families with two or more previously diagnosed coeliac disease patients. The value of the serum endomysial antibody test as a single means of detecting clinically silent coeliac disease was evaluated. The correlation of endomysial and tissue transglutaminase antibodies and the correlation of endomysial antibodies to the HLA typical for coeliac disease was determined. METHODS: A total of 137 multiple-case coeliac disease families with 872 family members were recruited; 466 healthy family members were simultaneously screened for gliadin and endomysial antibodies and thereafter for tissue tranglutaminase antibodies. Antibody-positive persons were typed for HLA-DQ2 and DQ8. The diagnosis of coeliac disease was based on the typical mucosal lesion on small-bowel biopsies. RESULTS: Forty-four (9.4%) of the healthy family members were positive for endomysial and 48 (10.3%) for gliadin antibodies; 42 biopsies revealed 29 new coeliac disease patients (6.2% of healthy individuals). Endomysial antibodies detected 97% and gliadin antibodies 52% of the new cases. All 44 endomysial-antibody-positive and 35 of 48 gliadin-antibody-positive individuals were positive for DQ2. Tissue transglutaminase antibodies corresponded well with endomysial antibodies. CONCLUSIONS: Undetected coeliac disease is common even among healthy first-degree relatives of multiple case families. The findings emphasize the value of serum endomysial antibodies in the detection of clinically silent coeliac disease. Endomysial-antibody-positive individuals, unlike gliadin-antibody-positive ones, share the coeliac disease-type HLA-DQ.

Adult↗
PubMed2002

Blisters in the small intestinal mucosa of coeliac patients contain T cells positive for cyclooxygenase 2.

BACKGROUND AND AIMS: Coeliac disease is characterised by atrophy of the villi and hyperplasia of the crypts in the mucosa of the small intestine. It is caused by an environmental trigger, cereal gluten, which induces infiltration of the mucosa by inflammatory cells. We hypothesised that these inflammatory cells express cyclooxygenase 2 (COX-2), an enzyme that contributes to the synthesis of pro and anti-inflammatory prostaglandins and is known to be expressed at sites of inflammation in the stomach and colon. We have investigated expression of COX-2 in the coeliac disease affected small intestinal mucosa where it may be an indicator of either disease induction or mucosal restoration processes. PATIENTS AND METHODS: Small intestinal biopsy samples from 15 coeliac patients and 15 non-coeliac individuals were stained immunohistochemically for COX-2. Samples from 10 of the patients were also stained after these patients had been on a gluten free diet for 6-24 months. Various cell type marker antigens were used for immunohistochemical identification of the type of cell that expressed COX-2. To further verify colocalisation of the cell type marker and COX-2, double immunoperoxidase and immunofluorescence methods were employed. Immunoelectron microscopy was used to investigate the subcellular location of COX-2. RESULTS: In all samples taken from coeliac patients, clusters of cells with strong immunoreactivity for COX-2 were found in those areas of the lamina propria where the epithelium seemed to blister or was totally detached from the basement membrane. These clusters were reduced in number or totally absent in samples taken after a gluten free diet. No such clusters were seen in any control samples. The density of COX-2 positive cells lining the differentiated epithelium decreased significantly from 13.5 (5.1) cells/10(5) microm(2) (mean (SD)) in the untreated patient samples to 6.5 (2.0) cells/10(5) microm(2) after a gluten free diet (p<0.001), and was 3.3 (1.9) cells/10(5) microm(2) in control samples (p<0.001 compared with untreated or diet treated coeliac samples). Staining for COX-2 was localised to CD3+ T cells and CD68+ macrophages in the mucosal lesions but not all of these cells were positive for COX-2. Immunoelectron microscopy revealed that the ultrastructure of the COX-2 positive cells resembled that of lymphocytes, and the immunoreaction was localised to the rough endoplasmic reticulum and the nuclear envelope. CONCLUSIONS: Our results show that in coeliac disease, blistering of small intestinal epithelial cells is associated with accumulation of COX-2 positive T cells, and the number of these cells decreases after a gluten free diet. These observations suggest that COX-2 mediated prostanoid synthesis contributes to healing of the coeliac mucosa and may be involved in maintenance of intestinal integrity.

Adolescent↗
PubMed2002

No harm from five year ingestion of oats in coeliac disease.

BACKGROUND: Six to 12 months of ingestion of moderate amounts of oats does not have a harmful effect in adult patients with coeliac disease. As the safety of long term intake of oats in coeliac patients is not known, we continued our previous 6-12 month study for five years. AIM: To assess the safety of long term ingestion of oats in the diet of coeliac patients. PATIENTS: In our previous study, the effects of a gluten free diet and a gluten free diet including oats were compared in a randomised trial involving 92 adult patients with coeliac disease (45 in the oats group, 47 in the control group). After the initial phase of 6-12 months, patients in the oats group were allowed to eat oats freely in conjunction with an otherwise gluten free diet. After five years, 35 patients in the original oats group (23 still on an oats diet) and 28 in the control group on a conventional gluten free diet were examined. METHODS: Clinical and nutritional assessment, duodenal biopsies for conventional histopathology and histomorphometry, and measurement of antiendomysial, antireticulin, and antigliadin antibodies. RESULTS: There were no significant differences between controls and those patients consuming oats with respect to duodenal villous architecture, inflammatory cell infiltration of the duodenal mucosa, or antibody titres after five years of follow up. In both groups histological and histomorphometric indexes improved equally with time. CONCLUSIONS: This study provides the first evidence of the long term safety of oats as part of a coeliac diet in adult patients with coeliac disease. It also appears that the majority of coeliac patients prefer oats in their diet.

Adult↗
PubMed2001

Differentially expressed CC3/TIP30 and rab11 along in vivo and in vitro intestinal epithelial cell crypt-villus axis.

We have previously shown that transforming growth factor-beta1 (TGF-beta1) is involved in the fibroblast-induced organization and differentiation of transformed phenotypically crypt-like T84 intestinal epithelial cells into absorptive enterocyte-like cells, when cultured within a three-dimensional collagen gel. We have used differential display polymerase chain reaction to find genes that are either up- or downregulated by TGF-beta in the T84 cells cultured in three-dimensional collagen gel and then studied how these in vitro differentially expressed genes are expressed in vivo in the small intestinal crypt-villus axis. We found that the TGF-beta1-treated T84 cells, like the villus tip enterocytes, expressed increased levels of CC3/TIP30 when compared to the undifferentiated cells. Furthermore, the expression of rab11 showed the opposite pattern, being higher in the undifferentiated cells both in vivo and in vitro. We conclude that the three-dimensional cell culture model where TGF-beta induces organization and differentiation of secretory T84 epithelial cells makes it possible to find up- and downregulated transcripts that also play a role in the human small intestinal crypt-villus axis.

Acetyltransferases↗
PubMed2001

Celiac disease without villous atrophy: revision of criteria called for.

Current diagnostic criteria of celiac disease require small bowel villous atrophy, although the damage develops gradually. We therefore searched for evidence of disease in 10 adults suspected to have celiac disease, but evincing only minor mucosal inflammation and increase in gammadelta+ cells without villous atrophy. Twenty untreated celiac and 27 nonceliac patients served as biopsy controls. CD3+, alphabeta+, and gammadelta+ cells were increased in patients with only minor mucosal lesions, but less than in celiac patients. The inflammation resolved on gluten-free diet, and abdominal symptoms were alleviated. Eight of 10 had positive endomysial, seven gliadin, and nine tissue transglutaminase antibodies; all normalized on diet. Eight patients had osteopenia; HLA DQ2 was found in all. Minor mucosal lesions with an increase in gammadelta+ intraepithelial lymphocytes were suggestive of celiac disease. Our patients showed a clinical, histological, and serological recovery on diet; risk of osteopenia speaks in favor of dietary treatment.

Adult↗
PubMed2001

Induction of nitric oxide synthesis by probiotic Lactobacillus rhamnosus GG in J774 macrophages and human T84 intestinal epithelial cells.

BACKGROUNDS AND AIMS: Probiotic Lactobacillus rhamnosus GG (LGG) has proved to be beneficial in the treatment of viral- and antibiotic-associated diarrhea but the mechanisms of action remain unknown. Nitric oxide (NO) is involved in the protective mechanisms in the gastrointestinal tract and may contribute to some of the beneficial effects of probiotics. The aim of the present study was to investigate if induction of NO synthesis is involved in the cellular actions of LGG. METHODS: NO synthesis and its regulation were measured in cultures of J774 murine macrophages and human T84 colon epithelial cells. NO production was measured as its metabolite nitrite accumulated into the culture medium. Inducible nitric oxide synthase (iNOS) protein and iNOS mRNA were detected by Western blot and RT-PCR, respectively. RESULTS: In J774 macrophages, LGG induced a low level production of NO in the presence of gamma interferon (IFNgamma) and it was inhibited by NOS inhibitors, cycloheximide and by a NF-kappa B inhibitor pyrrolidinedithiocarbamate. Accordingly, LGG and IFNgamma-stimulation increased iNOS mRNA and protein levels. T84 cells produced NO in response to LGG when first primed with a combination of IL-1beta, TNFalpha and IFNgamma. Lipoteichoic acid (LA), an antigenic structure in gram-positive bacteria, also induced NO formation in J774 cells in the presence of IFNgamma suggesting that LA may be the active component in LGG. CONCLUSIONS: LGG induces NO production in J774 macrophages and in human T84 colon epithelial cells through induction of iNOS by a mechanism involving activation of transcription factor NF-kappaB. Induction of iNOS and low-level synthesis of NO may be involved in the protective actions of LGG in the gastrointestinal tract.

Cell Line↗
PubMed2001

Analysis of nucleotide sugars from cell lysates by ion-pair solid-phase extraction and reversed-phase high-performance liquid chromatography.

Analysis of nucleotide sugar metabolism is essential in studying glycosylation in cells. Here we describe practical methods for both extraction of nucleotide sugars from cell lysates and for their analytical separation. Solid-phase extraction cartridges containing graphitized carbon can be used for the purification of nucleotide sugars by using triethylammonium acetate buffer as a ion-pairing reagent for decreasing retention. After that they are separated by high-performance liquid chromatography using a C18 reversed-phase column and the same ion-pairing reagent for increasing retention. These new sample preparation and analysis methods enable good separation of structurally similar sugar nucleotides, compatibility with rapid evaporative concentration, and possibility to automation. Monitoring the production of GDP-deoxyhexoses in genetically engineered yeast and native bacterial cells are described here as specific applications.

Adsorption↗
PubMed2001

Cloning and expression of Helicobacter pylori GDP-l-fucose synthesizing enzymes (GMD and GMER) in Saccharomyces cerevisiae.

Helicobacter pylori is a Gram-negative gastric pathogen causing diseases from mild gastric infections to gastric cancer. The difference in clinical outcome has been suggested to be due to strain differences. H. pylori undergoes phase variation by changing its lipopolysaccharide structure according to the environmental conditions. The O-antigen of H. pylori contains fucosylated glycans, similar to Lewis structures found in human gastric epithelium. These Lewis glycans of H. pylori have been suggested to play a role in pathogenesis in the adhesion of the bacterium to gastric epithelium. In the synthesis of fucosylated structures, GDP-l-fucose is needed as a fucose donor. Here, we cloned the two key enzymes of GDP-l-fucose synthesis, H. pylori gmd coding for GDP-d-mannose dehydratase (GMD), and gmer coding for GDP-4-keto-6-deoxy-d-mannose-3,5-epimerase/4-reductase (GMER) and expressed them in an enzymatically active form in Saccharomyces cerevisiae. The end product of these enzymes, GDP-l-fucose was used as a fucose donor in a fucosyltransferase assay converting sialyl-N-acetyllactosamine to sialyl Lewis X.

Base Sequence↗
PubMed2001

Cow's milk protein-sensitive enteropathy at school age.

OBJECTIVES: Cow's milk protein-sensitive enteropathy (CMSE) may persist in children to school age. We sought to define the morphologic and immunohistochemical features of persistent CMSE. STUDY DESIGN: We studied 15 children with a definite diagnosis of CMSE on the basis of a blind challenge, 12 children with suspected cases of CMSE, 11 children with celiac disease, and 12 control children. RESULTS: Typical findings in children with CMSE were endoscopically visible lymphonodular hyperplasia of the duodenal bulb and lymphoid follicles without villous atrophy in biopsy samples. The patients with definite CMSE showed significantly increased densities of intraepithelial T cells skewed clearly to gammadelta(+) cells, compared with the control patients but fewer than in the patients with celiac disease. The study children showed no aberrant upregulation of HLA-DR expression in the duodenal mucosa, and the prevalence of HLA DQ2 antigen among them was equal to that in the control children. CONCLUSIONS: Our observations corroborated the claim that CMSE at school age is an identifiable clinical entity. Immunohistochemical findings suggest the abrogation of antigen tolerance locally on the gastrointestinal mucosa. A careful clinical assessment that includes a long elimination-challenge test supported by typical endoscopic and histologic findings form the basis for diagnosis.

Adolescent↗
PubMed2001

Candidate gene region 15q26 and genetic susceptibility to coeliac disease in Finnish families.

BACKGROUND: Studies in the Irish and British populations have indicated that chromosome region 15q26 could include a novel non-HLA-linked locus conferring genetic susceptibility to coeliac disease. The locus is of particular interest, since a type I diabetes risk locus, IDDM3, maps to the same position. It was tested whether this locus shows evidence for genetic linkage to coeliac disease in Finland. METHODS: Ninety-nine Finnish families with at least one affected sibpair were studied. Five microsatellite markers mapped within approximately 20 cM region on chromosome 15q26 were typed. Non-parametric linkage (NPL) scores and allelic transmission (TDT) were studied. RESULTS: No evidence for genetic linkage could be obtained by the NPL scores calculated by the Genehunter program. However, transmission/disequilibrium analysis (TDT) revealed that haplotype D15S107*1-D15S120*6 was statistically significantly more frequently transmitted to affected than expected by chance (TDT chi2 9.0; P = 0.003). The subgroup of families having this haplotype, however, did not differ from the others, regarding to disease manifestation, HLA status, or geographical origin. CONCLUSION: The 15q26 region appears not to be a major non-HLA susceptibility locus for gluten sensitivity in Finland, but a particular haplotype which may harbour a susceptibility gene was identified.

Celiac Disease↗