TGFB1 gene polymorphisms and inflammatory bowel disease

Construction of a circular RNA-based competing endogenous RNA network to screen biomarkers related to intervertebral disc degeneration

Background

Intervertebral disc degeneration (IDD) is a leading cause of disability with limited treatment strategies. A better understanding of the mechanism of IDD might enable less invasive and more targeted treatments. This study aimed to identify the circular RNA (circRNA)–microRNA (miRNA)–messenger RNA (mRNA) competing endogenous RNA (ceRNA) regulatory mechanisms in IDD.

Methods 

The GSE67567 microarray dataset was downloaded from the Gene Expression Omnibus database. After data preprocessing, differentially expressed circRNAs, miRNAs and mRNAs between IDD and controls were identified. A ceRNA network was constructed on the basis of the interaction between circRNAs and miRNAs, and miRNAs and mRNAs. Pathway enrichment analysis was performed on the mRNAs in the ceRNA network. Then, with ‘intervertebral disc degeneration’ as keywords, IDD-related Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were searched for in the Comparative Toxicogenomics Database.

Results

A total of 105 differentially expressed circRNAs, 84 miRNAs and 967 mRNAs were identified. After analysis, 86 circRNA–miRNA, and 126 miRNA–mRNA regulatory relationship pairs were obtained to construct a ceRNA network. The mRNAs were enriched in six KEGG signalling pathways, and four were associated with IDD: the hsa04350: TGF-beta signalling pathway, hsa04068: FoxO signalling pathway, hsa05142: Chagas disease (American trypanosomiasis) and hsa04380: Osteoclast differentiation. An IDD-related ceRNA network was constructed involving four circRNAs, three miRNAs and 11 mRNAs. Auxiliary validation showed that the expression levels of miR-185-5p, miR-486-5p, ACVR1B, FOXO1, SMAD2 and TGFB1 were consistent in different databases.

Conclusions

Our study identified some circRNA–miRNA–mRNA interaction axes potentially associated with the progression of IDD, viz.: circRNA_100086–miR-509-3p–MAPK1, circRNA_000200–miR-185-5p–TGFB1, circRNA_104308–miR-185-5p–TGFB1, circRNA_400090–miR-486-5p–FOXO1 and circRNA_400090–miR-486-5p–SMAD2.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05579-0.

1. An IDD-related ceRNA network involving four circRNAs, three miRNAs and 11 mRNAs was constructed.

2. The expression levels of miR-185-5p, miR-486-5p, FOXO1, SMAD2 and TGFB1 were consistent in different databases.

3. Our study identified IDD-related circRNA–miRNA–mRNA interaction axes, including circRNA_100086–miR-509-3p–MAPK1.

Effect of Chronic Vitamin D Deficiency on the Development and Severity of DSS-Induced Colon Cancer in Smad3-/- Mice

Both human epidemiologic data and animal studies suggest that low serum vitamin D increases the risk of inflammatory bowel disease (IBD) and consequently IBD-associated colorectal cancer. We tested the hypothesis that vitamin D deficiency increases the risk for colitis-associated colon cancer (CAC) by using an established CAC mouse model, 129-Smad3tm1Par/J (Smad3-/-) mice, which have defective transforming growth factor β-signaling and develop colitis and CAC after the administration of dextran sodium sulfate (DSS). After determining a dietary regimen that induced chronic vitamin D deficiency in Smad3-/- mice, we assessed the effects of vitamin D deficiency on CAC. Decreasing dietary vitamin D from 1 IU/g diet (control diet) to 0.2 IU /g diet did not decrease serum 25-hydroxyvitamin D (25(OH)D) levels in Smad3-/- mice. A diet devoid of vitamin D (< 0.02 IU/g diet [no added vitamin D]; vitamin D-null) significantly decreased serum 25(OH)D levels in mice after 2 wk (null compared with control diet: 8.4 mg/mL compared with 12.2 ng/mL) and further decreased serum levels to below the detection limit after 9 wk but did not affect weight gain, serum calcium levels, bone histology, or bone mineral density. In light of these results, Smad3-/- mice were fed a vitamin D-null diet and given DSS to induce colitis. Unexpectedly, DSS-treated Smad3-/- mice fed a vitamin D-null diet had improved survival, decreased colon tumor incidence (8% compared with 36%), and reduced the incidence and severity of colonic dysplasia compared with mice fed the control diet. These effects correlated with increased epithelial cell proliferation and repair early in the disease, perhaps reducing the likelihood of developing chronic colitis and progression to cancer. Our results indicate that vitamin D deficiency is beneficial in some cases of CAC, possibly by promoting intestinal healing.

Genetic Influences on the Development of Fibrosis in Crohn's Disease

Fibrostenotic strictures are an important complication in patients with Crohn’s disease (CD), very often necessitating surgery. This fibrotic process develops in a genetically susceptible individual and is influenced by an interplay with environmental, immunological, and disease-related factors. A deeper understanding of the genetic factors driving this fibrostenotic process might help to unravel the pathogenesis, and ultimately lead to development of new, anti-fibrotic therapy. Here, we review the genetic factors that have been associated with the development of fibrosis in patients with CD, as well as their potential pathophysiological mechanism(s). We also hypothesize on clinical implications, if any, and future research directions.

Polymorphisms of the cytokine genes TGFB1 and IL10 in a mixed-race population with Crohn's disease

Background

Most Crohn’s disease (CD) genes discovered in recent years are associated with biological systems critical to the development of this disease. TGFB1 and IL10 are cytokines with important roles in CD. The aim of this study was to evaluate the association between CD, its clinical features and TGFB1 and IL10 gene polymorphisms.

Methods

This case–control study enrolled 91 patients and 91 controls from the state of Bahia, Brazil. Five single nucleotide polymorphisms (SNPs) were studied in the TGFB1 gene (codon 10 T > C - rs1800470; codon 25 G > C - rs1800471) and IL10 gene (−1082 A > G - rs1800896; -819 T > C - rs1800871; -592 A > C - rs1800872). An analysis of the genetic polymorphisms was performed using a commercial kit. A comparison of allele frequencies and genotypes was estimated by calculating the odds ratio (OR) with a confidence interval adjusted via the Bonferroni test for a local alpha of 1%. A stratified analysis was applied for gender, race and smoking history. Patients with CD were characterized according to the Montreal classification.

Results

The C allele and CC genotype of the TGFB1 gene rs1800470 were both significantly associated with CD. The stratified analysis showed no confounding factors for the co-variables of gender, race and smoking history. The IL10 gene rs1800896 G allele was significantly associated with age at diagnosis of CD, while the T allele of the IL10 gene rs1800871 was significantly associated with perianal disease. The SNPs rs1800871 and rs1800872 were in 100% linkage disequilibrium.

Conclusions

TGFB1 gene polymorphisms may be associated with susceptibility to the development of CD, and IL10 gene polymorphisms appear to influence the CD phenotype in this admixed population.

Bacterial infection of Smad3/Rag2 double-null mice with transforming growth factor-beta dysregulation as a model for studying inflammation-associated colon cancer

Alterations in genes encoding transforming growth factor-beta-signaling components contribute to colon cancer in humans. Similarly, mice deficient in the transforming growth factor-beta signaling molecule, Smad3, develop colon cancer, but only after a bacterial trigger occurs, resulting in chronic inflammation. To determine whether Smad3-null lymphocytes contribute to increased cancer susceptibility, we crossed Smad3-null mice with mice deficient in both B and T lymphocytes (Rag2(-/-) mice). Helicobacter-infected Smad3/Rag2-double knockout (DKO) mice had more diffuse inflammation and increased incidence of adenocarcinoma compared with Helicobacter-infected Smad3(-/-) or Rag2(-/-) mice alone. Adoptive transfer of WT CD4(+)CD25(+) T-regulatory cells provided significant protection of Smad3/Rag2-DKO from bacterial-induced typhlocolitis, dysplasia, and tumor development, whereas Smad3(-/-) T-regulatory cells provided no protection. Immunohistochemistry, real-time reverse transcriptase-polymerase chain reaction, and Western blot analyses of colonic tissues from Smad3/Rag2-DKO mice 1 week after Helicobacter infection revealed an influx of macrophages, enhanced nuclear factor-kappaB activation, increased Bcl(XL)/Bcl-2 expression, increased c-Myc expression, accentuated epithelial cell proliferation, and up-regulated IFN-gamma, IL-1alpha, TNF-alpha, IL-1beta, and IL-6 transcription levels. These results suggest that the loss of Smad3 increases susceptibility to colon cancer by at least two mechanisms: deficient T-regulatory cell function, which leads to excessive inflammation after a bacterial trigger; and increased expression of proinflammatory cytokines, enhanced nuclear factor-kappaB activation, and increased expression of both pro-oncogenic and anti-apoptotic proteins that result in increased cell proliferation/survival of epithelial cells in colonic tissues.

Promoter polymorphism of transforming growth factor-β1 gene and ulcerative colitis

AIM: To elucidate the possible difference in two promoter polymorphisms of the transforming growth factor-β1 (TGF-β1) gene (-800G > A, -509C > T) between ulcerative colitis (UC) patients and normal subjects.

METHODS: A total of 155 patients with established ulcerative colitis and 139 normal subjects were selected as controls. Two single nucleotide polymorphisms within the promoter region of TGF-β1 gene (-509C > T and -800G > A) were genotyped using PCR-RFLP.

RESULTS: There was a statistically significant difference in genotype and allele frequency distributions between UC patients and controls for the -800G > A polymorphism of the TGF-β1 gene (P < 0.05). The frequency of the TGF-β1 gene polymorphism at position -800 showed that the AA genotype and the allele A frequencies significantly differed between the patients and healthy controls (P < 0.05). At position -509, there was no statically significant difference in genotype and allele frequency between the patients and control subjects.

CONCLUSION: The results of our study indicate that there is a significant difference in both allele and genotype frequency at position -800G > A of TGF-β1 gene promoter between Iranian patients with UC and normal subjects.

Gastric cancer susceptibility is not linked to pro-and anti-inflammatory cytokine gene polymorphisms in whites: a Nationwide Multicenter Study in Spain

BACKGROUND AND AIMS

Recent studies have reported an association between cytokine gene polymorphisms and GC risk. However, results are inconsistent among studies from different geographic regions and ethnic groups. Our goal was to evaluate the influence of Helicobacter pylori (H. pylori) infection and host genetic factors on GC susceptibility in a population of Spanish white GC patients.

METHODS

DNA from 404 unrelated patients with GC and 404 sex- and age-matched healthy controls was typed for several functional polymorphisms in pro- (IL-1B, TNFA, LTA, IL-12p40) and anti-inflammatory (IL-4, IL-1RN, IL-10, TGFB1) genes by PCR, RFLP, and TaqMan assays. H. pylori infection and CagA/VacA antibody status were also determined by western blot serology.

RESULTS

Logistic regression analysis identified H. pylori infection with cagA strains (OR 2.54, 95% CI 1.77-3.66), smoking habit (OR 1.91, 95% CI 1.25-2.93), and positive family history of GC (OR 3.67, 95% CI 2.01-6.71) as independent risk factors for GC. None of the cytokine gene polymorphisms analyzed in this study were associated with susceptibility to GC development, whether GC patients were analyzed as a group or categorized according to anatomic location or histological subtype. Some simultaneous combinations of proinflammatory genotypes reportedly associated with greater GC risk yielded no significant differences between patients and controls.

CONCLUSIONS

Our results show that, at least in some white populations, the contribution of the cytokine gene polymorphisms evaluated in this study (IL-1B, IL-1RN, IL-12p40, LTA, IL-10, IL-4, and TGF-B1) to GC susceptibility may be less relevant than previously reported.

Angiotensinogen and transforming growth factor beta1: novel genes in the pathogenesis of Crohn's disease

BACKGROUND

Angiotensin peptides may act locally as cytokines in several organ systems with elevated mucosal levels present in Crohn's disease. A variant in the angiotensinogen gene promoter results in increased peptide production, while transforming growth factor beta1 (TGFbeta1) codon 25 variants demonstrate variable peptide production, predisposing to fibrosis in several organs.

AIMS

Conduct an Australian-based analysis of the angiotensinogen-6 variant in two independent inflammatory bowel disease (IBD) cohorts, and examine the role of angiotensinogen-6 and TGFbeta1 codon 25 variants in shaping Crohn's disease phenotype.

METHODS

IBD Patients (Crohn's disease = 347, ulcerative colitis = 147) and CD families (n = 148) from two cohorts, together with 185 healthy controls were genotyped for angiotensinogen-6. Genotype-phenotype analyses were performed for both angiotensinogen-6 and TGFbeta1 codon 25.

RESULTS

Angiotensinogen-6 AA genotype was significantly associated with Crohn's disease (p = 0.007, OR = 2.38, CI = 1.32-4.32) in cohort 1, but not in the smaller cohort 2 (p = 0.19). The association remained significant when the two cohorts were combined (p = 0.008), and in a TDT family analysis (p = 0.03). TGF 1 codon 25 was associated with stricturing Crohn's disease (p = 0.01, OR = 2.63, CI = 1.16-5.88) and a shorter time to intestinal resection (p = 0.06).

CONCLUSIONS

The association of the angiotensinogen-6 variant with Crohn's disease supports a potential role for angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists in disease treatment.

TGFB1 gene polymorphisms: their relevance in the susceptibility to Helicobacter pylori-related diseases

Recent studies have revealed elevated expression of transforming growth factor beta1 (TGF-beta1) in gastric mucosa of patients with gastric cancer (GC) and those undergoing ulcer repair. As production of TGF-beta1 is genetically regulated, we aimed to assess whether functional polymorphisms of the TGFB1 gene are involved in susceptibility to and clinical characteristics of Helicobacter pylori-related diseases. DNA from 142 unrelated Spanish patients with GC, 200 with peptic ulcer and 342 healthy controls was typed for the MspA1I T+869C, and the Sau96I G+915C polymorphisms of the TGFB1 gene using polymerase chain reaction and RFLP analysis. H. pylori infection and CagA/VacA antibody status were determined by Western blot in patients and controls. H. pylori infection (odds ratio (OR): 11.44; 95% confidence interval (CI): 4.45-29.42; P<0.001) and non-steroidal anti-inflammatory drugs (OR: 5.07; 95% CI: 2.53-10.16; P<0.001) were identified as independent risks factors for duodenal ulcer (DU), whereas the TGFB1+869(*)C/C genotype was associated with reduced risk of developing the disease (OR: 0.32; 95% CI=0.15-0.68; P=0.003). Our results show that the TGFB1 T+869C gene polymorphism is involved in the susceptibility to DU and provide further evidence that host genetic factors play a key role in the pathogenesis of H. pylori-related diseases.

Helicobacter infection is required for inflammation and colon cancer in SMAD3-deficient mice

Accumulating evidence suggests that intestinal microbial organisms may play an important role in triggering and sustaining inflammation in individuals afflicted with inflammatory bowel disease (IBD). Moreover, individuals with IBD are at increased risk for developing colorectal cancer, suggesting that chronic inflammation may initiate genetic or epigenetic changes associated with cancer development. We tested the hypothesis that bacteria may contribute to the development of colon cancer by synergizing with defective transforming growth factor-beta (TGF-beta) signaling, a pathway commonly mutated in human colon cancer. Although others have reported that mice deficient in the TGF-beta signaling molecule SMAD3 develop colon cancer, we found that SMAD3-deficient mice maintained free of the Gram-negative enterohepatic bacteria Helicobacter spp. for up to 9 months do not develop colon cancer. Furthermore, infection of SMAD3(-/-) mice with Helicobacter triggers colon cancer in 50% to 66% of the animals. Using real-time PCR, we found that Helicobacter organisms concentrate in the cecum, the preferred site of tumor development. Mucinous adenocarcinomas develop 5 to 30 weeks after infection and are preceded by an early inflammatory phase, consisting of increased proliferation of epithelial cells; increased numbers of cyclooxygenase-2-positive cells, CD4(+) T cells, macrophages; and increased MHC class II expression. Colonic tissue revealed increased transcripts for the oncogene c-myc and the proinflammatory cytokines interleukin-1alpha (IL-1alpha), IL-1beta, IL-6, IFN-gamma, and tumor necrosis factor-alpha, some of which have been implicated in colon cancer. These results suggest that bacteria may be important in triggering colorectal cancer, notably in the context of gene mutations in the TGF-beta signaling pathway, one of the most commonly affected cellular pathways in colorectal cancer in humans.

Mechanisms of nitric oxide-mediated intestinal barrier failure in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the leading intestinal emergency in premature infants. The underlying etiology of NEC remains elusive, but hypoxic conditions and early enteral feeding are consistently implicated as the main risk factors in the pathogenesis of NEC. We postulate that nitric oxide (NO) plays a key role as a molecular signaling "hub" in the generation of gut barrier failure in NEC. Clinical studies suggest that inflammatory cytokines and excessive NO production may contribute to the pathogenesis of NEC. One of the major challenges in defining the critical signaling pathways that lead to the development of NEC is the lack of specific biochemical markers that consistently delineate the early stages of NEC. Intestinal pathology and molecular markers derived from late-stage NEC represent end-stage findings and thus provide little insight into the early events that led to intestinal inflammation. Such markers may not represent viable therapeutic targets for the treatment or prevention of NEC. Therefore, novel strategies are needed to identify the patients at risk for NEC and define the clinically relevant molecules that characterize the early stages of NEC. This review will examine the mechanisms of NO-mediated gut barrier failure and propose novel genetic-based approaches for elucidating the critical molecular pathways in NEC.

The role of cytokine gene polymorphisms in determining disease susceptibility and phenotype in inflammatory bowel disease

BACKGROUND AND AIMS

Emerging data indicate that alterations in cytokine synthesis may play a role in inflammatory bowel disease (IBD) pathogenesis. The differential production of cytokines has been linked to single nucleotide polymorphisms in gene promoter regions, signal sequences, and gene introns. The aim of this study was to assess the relationship between polymorphisms involving five cytokine genes (TNF-alpha, TGF-beta, IL-10, IL-6, and IFN-gamma), and IBD susceptibility and disease phenotype.

METHODS

Cytokine genotyping was performed utilizing polymerase chain reaction. The specific gene polymorphisms that were probed for included: -1082(G/A), -819(T/C), and -592(A/C) in the IL-10 promoter, -308(G/A) in the TNF-alpha promoter, codon 10 (T/C), and codon 25 (G/C) of the TGF-beta signal sequence, +874(T/A) of intron 1 of IFN-gamma, and -174(C/G) in the IL-6 promoter.

RESULTS

A total of 193 IBD patients (138 Crohn's disease (CD) and 55 ulcerative colitis (UC)) and 92 controls were evaluated. No association between IBD, UC, or CD susceptibility and the cytokine gene polymorphisms were found. Patients with ileocolonic CD were more likely to possess the IL-6 -174 GG genotype compared to those with nonileocolonic disease (p= 0.006). Patients with ileal CD were more likely to possess the IL-6 -174 GC genotype compared to those with nonileal disease (p= 0.0004). An increased number of CD patients with isolated colonic disease possessed the IL-6 -174 CC genotype compared to those with nonisolated colonic disease (p= 0.032).

CONCLUSION

The cytokine gene polymorphisms studied here do not appear to influence IBD susceptibility. There does, however, appear to be an influence on disease phenotype, particularly on CD site.

Susceptibility to ankylosing spondylitis: no evidence for the involvement of transforming growth factor beta 1 (TGFB1) gene polymorphisms

BACKGROUND

Genetic factors are thought to be crucial in the pathogenesis of ankylosing spondylitis. Transforming growth factor beta 1 (TGF beta 1) is a multifunctional cytokine that plays a key role in inflammation. Two functional single nucleotide polymorphisms (SNPs) in the TGFB1 gene have been described: TGFB1 T869C and TGFB1 G915C.

OBJECTIVE

To determine whether these SNPs contribute to ankylosing spondylitis susceptibility or its disease characteristics.

METHODS

Genomic DNA was isolated from the peripheral blood of 134 patients with ankylosing spondylitis and 194 healthy blood donors. All subjects were unrelated and of white Dutch ethnicity. The diagnosis of ankylosing spondylitis was made according to the modified New York criteria. The TGFB1 T869C and TGFB1 G915C SNPs were genotyped by a polymerase chain reaction-single strand conformation polymorphism haplotyping method.

RESULTS

No significant differences were found between patients and controls in genotype, allele, and haplotype frequencies or in the carrier rate of the rare alleles of the TGFB1 T869C and TGFB1 G915C SNPs.

CONCLUSIONS

TGFB1 T869C and TGFB1 G915C SNPs are not major factors in the susceptibility to ankylosing spondylitis or its disease characteristics.

The transforming growth factor-beta1 gene polymorphism (G915C) is not associated with systemic lupus erythematosus

Lymphocyte production of transforming growth factor (TGF)-beta1 is decreased in systemic lupus erythematosus (SLE). The lack of this immunoregulatory cytokine may contribute to the characteristic T cell disregulation and aberrant B cell stimulation in SLE patients. The less common C allele of the TGFB1 polymorphism (G915C) is associated with a lower TGF-beta1 production capacity. We performed a population-based case-control study to analyse the impact of this polymorphism on disease susceptibility, on clinical SLE manifestations and autoantibody production. A total of 203 German Caucasian SLE patients (fulfilling the 1982 ACR disease duration 11.5 +/- 7.0 years) and 158 ethnically, age- and sex-matched healthy controls were genotyped with a mutagenically separated polymerase chain reaction. There were no significant differences in the genotype distribution and allele frequencies between patients (915 C = 0.08) and healthy controls (915 C = 0.10). Comparing subgroups of patients, we found no association of major disease manifestations or specific autoantibodies with TGFB1 genotypes or alleles. The TGFB1 polymorphism (G915C) neither significantly contributes to the disease susceptibility, nor predisposes to clinical and immunological manifestations typical of SLE. Further studies are needed to corroborate the pathogenic role of TGF-beta1 in SLE patients and to identify the precise genetic elements controlling its production.

Polymorphisms of transforming growth factor-beta1 and transforming growth factor-beta1 type II receptor genes are associated with acute graft-versus-host disease in children with HLA-matched sibling bone marrow transplantation

The aim of this study was to determine whether the gene polymorphisms of Th1/Th2 and immunoregulatory cytokines were associated with aGVHD in Japanese children receiving allogeneic bone marrow transplantation (allo BMT). We investigated polymorphisms of genes encoding interleukin (IL)-4, IL-4 receptor (IL-4 R), IL-10, transforming growth factor (TGF)-beta1, TGF-beta1 type II receptor (TGF-beta1 RII), interferon (IFN)-gamma, IFN-gamma type 2 receptor (IFN-gamma R2), and IFN regulatory factor (IRF)-1. Sixty-seven patients were treated with allo BMT from HLA-identical siblings, and aGVHD was observed in 38. TGF-beta1 codon 10 leucine (Leu) /proline (Pro) polymorphism in donors was associated with the development of aGVHD. Patients having donors with the Pro allele had aGVHD more frequently than those without Pro allele (30/45 vs 8/20, odds ratio = 3.00; P = 0.04). TGF-beta1 RII 1167 C/T polymorphism in recipients was also associated with the development of aGVHD. The incidence was significantly higher in recipients with T allele than in those without T allele (21/27 vs 16/35, odds ratio = 4.16; P = 0.01). In conclusion, genetic backgrounds of TGF-beta1 and TGF-beta1 RII may be involved in the development of aGVHD in HLA-matched sibling BMT in Japanese children.

The polymorphism of transforming growth factor-beta1 gene in Japanese patients with systemic sclerosis

BACKGROUND

Transforming growth factor (TGF)-beta has been shown to be a potent stimulator of collagen production by fibroblasts, and could play a role in the pathogenesis of systemic sclerosis (SSc).

OBJECTIVE

To study the possible involvement of TGF-beta1 gene polymorphism in Japanese patients with SSc.

METHODS

Fifty-nine patients with SSc and 110 normal subjects were studied. Genomic DNA was extracted from skin tissues, and was amplified in a thermal cycler, generating a TGF-beta1 gene fragment with a size of 294 bp. The T to C transition at T869C (Leu10Pro) and the G to C transition at G915C (Arg25Pro) were identified by digestion with MspA1I and BglI, respectively.

RESULTS

At T869C (Leu10Pro), the frequency of the C allele in SSc (65.3%) was significantly higher than in normal controls (50.5%) (P < 0.01). SSc showed C/C allele 42.4%, C/T 45.8% and T/T 11.2%. Normal controls showed C/C allele 26.4%, C/T 48.2% and T/T 25.5%. The frequency of the C/C allele in SSc was significantly higher than in normal controls, in comparison with the T/T allele (P < 0.02), but no significant difference was found between the frequency of the C/C allele vs. the C/T allele. The frequency of the C/C allele showed no significant difference between diffuse and limited SSc. At G915C (Arg25Pro), all the normal controls and SSc patients showed only the G/G allele. These results are different from a previous study in which the frequency of the T/T allele was high in SSc at T869C (Leu10Pro).

CONCLUSIONS

This discrepancy may indicate that Japanese patients with SSc show a different genetic predisposition to TGF-beta1.

Intestinal fibrosis in human and experimental inflammatory bowel disease

Fibrosis is a serious complication of Crohn disease for which there is no effective therapy. It is unclear why fibrosis, particularly fibrosis of the mucosal layer, develops in Crohn disease and not in ulcerative colitis. Smooth muscle cells, subepithelial myofibroblasts, and fibroblasts have traditionally been considered mediators of fibrosis, but new information points to a role of interstitial cells of Cajal and mast cells. Recent evidence about the role of each of these cell types in fibrosis in Crohn disease or other inflammatory bowel diseases is described. Hypothetical models to describe how altered function of these cells could underlie fibrosis of the mucosa or submucosal layers are presented. Fibrosis is not well characterized in any animal model of inflammatory bowel disease. The merits of several animal models for defining the mechanisms of inflammation-induced intestinal fibrosis are reviewed.