Serum angiotensin I-converting enzyme is reduced in Crohn's disease and ulcerative colitis irrespective of genotype

Angiotensin-converting enzymes 1 and 2 in the feces: presence and catalytic activity in the rat 2,4,6-trinitrobenzene sulfonic acid-induced model of colitis

BACKGROUND AND AIM

Inflammatory bowel disease is challenging to diagnose. Fecal biomarkers offer noninvasive solutions. The renin-angiotensin-aldosterone system is implicated in intestinal inflammation. Angiotensin-converting enzyme (ACE) and angiotensin-converting enzyme 2 (ACE2) regulate its activity, but conflicting findings on these enzymes in colitis require further investigation. We aimed to assess ACE and ACE2 presence and activities in the feces, serum, and colon of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced rats.

METHODS

Colitis was induced in male rats by rectal instillation of a 21% ethanolic TNBS solution. After rats' sacrifice, colonic portions, serum, and feces were collected. ACE and ACE2 presence in the feces was analyzed by western Blot, and colonic and serum enzymes' concentrations were quantified using ELISA kits. ACE activity was assessed using Hippuryl-His-Leu and Z-Phe-His-Leu as substrates. ACE2 activity was assessed using Mca-APK (Dnp) as a substrate in the presence and absence of DX600 (ACE2 inhibitor).

RESULTS

An ACE isoform of ~70 kDa was found only in the feces of TNBS-induced rats. ACE concentration was higher than that of ACE2 in the serum and the inflamed colon. ACE N-domain activity was higher than that of the C-domain in all matrices. ACE2 activity was higher in the feces of TNBS-induced animals compared to controls.

CONCLUSION

A 70 kDa ACE isoform only detected in the feces of TNBS-induced rats may have translational relevance. ACE N-domain seems to play a significant role in regulating colonic lesions. Further research using human samples is necessary to validate these findings.

Prognostic and therapeutic implication of m6A methylation in Crohn disease

BACKGROUND

N6-methyladenosine (m6A) methylation has been reported to participate in inflammatory bowel disease (including Crohn disease [CD]). However, the prognostic and therapeutic implication of m6A methylation modification in CD is still unclear.

METHODS

Genomic information of CD patients was integrated to assess disease-related m6A regulators, and difference and correlation analyses of m6A regulators were explored by using the R packages. Next, CD patients were classified by the expression of differential and intersecting genes in m6A regulators, and difference and correlation analyses were conducted among immune infiltration and therapeutic responses. Finally, colon tissue resected from patients with CD were assessed to verify expression of Wilms tumor 1-associated protein (WTAP) and METTL14 from these m6A regulators.

RESULTS

We identified 23 m6A regulators in CD patients. Difference analysis of these regulators showed that expression of METTL14, WTAP, RBM15 and YTHDF2/3 was upregulated in the treatment group compared with the control group, with expression of METTL3, YTHDF1, leucine-rich pentatricopeptide repeat motif-containing protein, HNRNPA2B1, IGF2BP1 and fat mass and obesity-associated protein downregulated. Moreover, RBM15, WTAP, leucine-rich pentatricopeptide repeat motif-containing protein, YTHDF1 and YTHDF3 were considered the characteristic genes of CD in m6A regulators. In addition, we identified 4 intersection genes of 3 m6A cluster patterns. Based on the expression of these intersection genes, difference analysis among m6A regulators indicated that the expression of 8 m6A regulators had statistical differences among the 3 geneCluster patterns. Assays of colon tissues from CD patients showed that expression of WTAP and METTL14 were higher in areas of stenosis than non-stenosis.

CONCLUSION

m6A methylation modification might affect disease risk, immune infiltration and therapeutic responses in CD. Evaluating the expression of m6A regulators might provide insight into the prediction of disease prognosis and therapeutic responses.

Thromboembolic and atherosclerotic cardiovascular events in inflammatory bowel disease: epidemiology, pathogenesis and clinical management

Inflammatory bowel disease (IBD) is associated with an increased risk of cardiovascular disease (CVD). The increased risk of CVD concerns an increased risk of venous thromboembolism (VTE), atherosclerotic cardiovascular disease (ASCVD) and heart failure (HF), at corresponding relative risks of 2.5, 1.2 and 2.0, respectively, as compared with the general population. Especially young patients under the age of 40 years run a relatively high risk of these complications when compared with the general population. Chronic systemic inflammation causes a hypercoagulable state leading to the prothrombotic tendency characteristic of VTE, and accelerates all stages involved during atherogenesis in ASCVD. Increased awareness of VTE risk is warranted in patients with extensive colonic disease in both ulcerative colitis and Crohn's disease, as well as during hospitalization, especially when patients are scheduled for surgery. Similarly, critical periods for ASCVD events are the 3 months prior to and 3 months after an IBD-related hospital admission. The increased ASCVD risk is not fully explained by an increased prevalence of traditional risk factors and includes pro-atherogenc lipid profiles with high levels of small dense low-density lipoprotein cholesterol particles and dysfunctional high-density lipoprotein cholesterol. Risk factors associated with HF are location and extent of inflammation, female sex, and age exceeding 40 years. A dose-dependent increase of overall CVD risk has been reported for corticosteroids. Immunomodulating maintenance therapy might reduce CVD risk in IBD, not only by a direct reduction of chronic systemic inflammation but possibly also by a direct effect of IBD medication on platelet aggregation, endothelial function and lipid and glucose metabolism. More data are needed to define these effects accurately. Despite accumulating evidence on the increased CVD risk in IBD, congruent recommendations to develop preventive strategies are lacking. This literature review provides an overview of current knowledge and identifies gaps in evidence regarding CVD risk in IBD, by discussing epidemiology, pathogenesis, and clinical management.

Interaction between the Renin-Angiotensin System and Enteric Neurotransmission Contributes to Colonic Dysmotility in the TNBS-Induced Model of Colitis

Angiotensin II (Ang II) regulates colon contraction, acting not only directly on smooth muscle but also indirectly, interfering with myenteric neuromodulation mediated by the activation of AT₁ /AT₂ receptors. In this article, we aimed to explore which mediators and cells were involved in Ang II-mediated colonic contraction in the TNBS-induced rat model of colitis. The contractile responses to Ang II were evaluated in distinct regions of the colon of control animals or animals with colitis in the absence and presence of different antagonists/inhibitors. Endogenous levels of Ang II in the colon were assessed by ELISA and the number of AT₁/AT₂ receptors by qPCR. Ang II caused AT₁ receptor-mediated colonic contraction that was markedly decreased along the colons of TNBS-induced rats, consistent with reduced AT₁ mRNA expression. However, the effect mediated by Ang II is much more intricate, involving (in addition to smooth muscle cells and nerve terminals) ICC and EGC, which communicate by releasing ACh and NO in a complex mechanism that changes colitis, unveiling new therapeutic targets.

Renin-angiotensin system promotes colonic inflammation by inducing TH17 activation via JAK2/STAT pathway

Previous studies suggest that the renin-angiotensin system (RAS) is a pathogenic factor for colitis. The goal of this study was to elucidate the molecular mechanism whereby angiotensin II (ANG II) promotes colonic inflammation. We found that renin was highly induced in colonic biopsies from patients with ulcerative colitis or Crohn's disease, and colonic renin and ANG II levels were markedly increased in a 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis model, indicating that the colonic RAS is activated in colitis. Renin transgenic (RenTg) mice exhibited increased phosphorylation in Janus kinase-2 (JAK2) and signal transducer and activator of transcription1/3 (STAT1/3) within colonic mucosa at baseline and following TNBS induction, suggesting that ANG II promotes colonic inflammation via the JAK2/STAT1/3 pathway. Treatment with pan-JAK inhibitor tofacitinib blocked JAK2 and STAT1/3 phosphorylation, attenuated T helper (T_H)1 and T_H17 responses, alleviated colitis, and prevented death of RenTg mice in TNBS model. ANG II stimulated JAK2/STAT1/3 phosphorylation in both Jurkat T lymphocytes and HCT116 epithelial cells. In vitro polarization assays demonstrated that ANG II directly promoted T_H17 polarization, but not T_H1 polarization, via JAK2/STAT1/3. ANG II stimulation of transforming growth factor-β1 (TGFβ1), IL-6, myosin light chain kinase, and p53 upregulated modulator of apoptosis in HCT116 cells was also mediated by JAK2/STAT1/3. These observations suggest that ANG II promotes T_H17 polarization directly as well as indirectly by inducing production of T_H17-polarizing cytokines (e.g., TGFβ1 and IL-6) from colonic epithelial cells, both via the JAK2/STAT pathway. Therefore, colonic RAS promotes colonic inflammation, at least in part, by stimulating T_H17 activation. NEW & NOTEWORTHY This study demonstrates that the local renin-angiotensin system in the colon is activated in colitis development, which promotes mucosal T helper cell activation through the JAK2/STAT pathway. These observations provide molecular evidence that the renin-angiotensin system is a pathogenic factor for the development of inflammatory bowel diseases.

Isolated Gastrointestinal Sarcoidosis Involving Multiple Gastrointestinal Sites Presenting as Chronic Diarrhea

Sarcoidosis is a chronic and systemic disorder characterized by the formation of non-caseating granulomas. Very few cases of isolated gastrointestinal sarcoidosis have been reported, and even fewer, if any, report gastrointestinal sarcoidosis within multiple gastrointestinal sites concomitantly. We present a 42-year-old white man with chronic diarrhea and abdominal pain for more than 3 years. Mucosal biopsies revealed non-caseating microgranulomas in the stomach, throughout the small intestine, colon, and rectum. Prednisone therapy was initiated with a rapid improvement in symptoms and complete resolution of diarrhea within 3 weeks.

Activation of the Renin-Angiotensin System Promotes Colitis Development

The renin-angiotensin system (RAS) plays pathogenic roles in renal and cardiovascular disorders, but whether it is involved in colitis is unclear. Here we show that RenTgMK mice that overexpress active renin from the liver developed more severe colitis than wild-type controls. More than 50% RenTgMK mice died whereas all wild-type mice recovered. RenTgMK mice exhibited more robust mucosal T_H17 and T_H1/T_H17 responses and more profound colonic epithelial cell apoptosis compared to wild-type controls. Treatment with aliskiren (a renin inhibitor), but not hydralazine (a smooth muscle relaxant), ameliorated colitis in RenTgMK mice, although both drugs normalized blood pressure. Chronic infusion of angiotensin II into wild-type mice mimicked the severe colitic phenotype of RenTgMK mice, and treatment with losartan [an angiotensin type 1 receptor blocker (ARB)] ameliorated colitis in wild-type mice, confirming a colitogenic role for the endogenous RAS. In human biopsies, pro-inflammatory cytokines were suppressed in patients with inflammatory bowel disease who were on ARB therapy compared to patients not receiving ARB therapy. These observations demonstrate that activation of the RAS promotes colitis in a blood pressure independent manner. Angiotensin II appears to drive colonic mucosal inflammation by promoting intestinal epithelial cell apoptosis and mucosal T_H17 responses in colitis development.

Anti-Inflammatory Action of Angiotensin 1-7 in Experimental Colitis

Background

There is evidence to support a role for angiotensin (Ang) 1–7 in reducing the activity of inflammatory signaling molecules such as MAPK, PKC and SRC. Enhanced angiotensin converting enzyme 2 (ACE2) expression has been observed in patients with inflammatory bowel disease (IBD) suggesting a role in its pathogenesis, prompting this study.

Methods

The colonic expression/activity profile of ACE2, Ang 1–7, MAS1-receptor (MAS1-R), MAPK family and Akt were determined by western blot and immunofluorescence. The effect of either exogenous administration of Ang 1–7 or pharmacological inhibition of its function (by A779 treatment) was determined using the mouse dextran sulfate sodium model.

Results

Enhanced colonic expression of ACE2, Ang1-7 and MAS1-R was observed post-colitis induction. Daily Ang 1–7 treatment (0.01–0.06 mg/kg) resulted in significant amelioration of DSS-induced colitis. In contrast, daily administration of A779 significantly worsened features of colitis. Colitis-associated phosphorylation of p38, ERK1/2 and Akt was reduced by Ang 1–7 treatment.

Conclusion

Our results indicate important anti-inflammatory actions of Ang 1–7 in the pathogenesis of IBD, which may provide a future therapeutic strategy to control the disease progression.

Upregulation of circulating components of the alternative renin-angiotensin system in inflammatory bowel disease: A pilot study

INTRODUCTION

The relationship between intestinal inflammation and circulating components of the renin-angiotensin system (RAS) is poorly understood.

MATERIALS AND METHODS

Demographic and clinical data were obtained from healthy controls and patients with inflammatory bowel disease (IBD). Plasma concentrations of the classical RAS components (angiotensin-converting enzyme (ACE) and angiotensin II (Ang II)) and alternative RAS components (ACE2 and angiotensin (1-7) (Ang (1-7))) were analysed by radioimmuno- and enzymatic assays. Systemic inflammation was assessed using serum C-reactive protein (CRP), white cell count, platelet count and albumin, and intestinal inflammation by faecal calprotectin.

RESULTS

Nineteen healthy controls (11 female; mean age 38 years, range 23-68), 19 patients with Crohn's disease (11 female; aged 45 years, range 23-76) and 15 patients with ulcerative colitis (6 female; aged 42 years, 26-64) were studied. Circulating classical RAS component levels were similar across the three groups, whereas ACE2 activity and Ang (1-7) concentrations were higher in patients with IBD compared to controls (ACE2: 21.5 vs 13.3 pmol/ml/min, p<0.05; Ang (1-7): 22.8 vs 14.1 pg/ml, p<0.001). Ang (1-7) correlated weakly with platelet and white cell counts, but not calprotectin or CRP, in patients with IBD.

CONCLUSIONS

Circulating components of the alternative RAS are increased in patients with IBD.

Review article: the pathophysiological roles of the renin-angiotensin system in the gastrointestinal tract

BACKGROUND

The renin-angiotensin system (RAS) is a homeostatic pathway widely known to regulate cardiovascular and renal physiology; however, little is known about its influence in gastrointestinal tissues.

AIM

To elicit the anatomical distribution and physiological significance of the components of the RAS in the gastrointestinal tract.

METHODS

An extensive online literature review including Pubmed and Medline.

RESULTS

There is evidence for RAS involvement in gastrointestinal physiology and pathophysiology, with all the components required for autonomous regulation identified throughout the gastrointestinal tract. The RAS is implicated in the regulation of glucose, amino acid, fluid and electrolyte absorption and secretion, motility, inflammation, blood flow and possibly malignant disease within the gastrointestinal tract. Animal studies investigating the effects of RAS blockade in a range of conditions including inflammatory bowel disease, functional gut disorders, gastrointestinal malignancy and even intestinal ischaemia have been encouraging to date. Given the ready availability of drugs that modify the RAS and their excellent safety profile, an opportunity exists for investigation of their possible therapeutic role in a variety of human gastrointestinal diseases.

CONCLUSIONS

The gastrointestinal renin-angiotensin system appears to be intricately involved in a number of physiological processes, and provides a possible target for novel investigative and therapeutic approaches.

Use of enterally delivered angiotensin II type Ia receptor antagonists to reduce the severity of colitis

BACKGROUND

Renin-angiotensin system blockade reduces inflammation in several organ systems. Having found a fourfold increase in angiotensin II type Ia receptor expression in a dextran sodium sulfate colitis model, we targeted blockade with angiotensin II type Ia receptor antagonists to prevent colitis development. Because hypotension is a major complication of angiotensin II type Ia receptor antagonists use, we hypothesized that use of angiotensin II type Ia receptor antagonists compounds which lack cell membrane permeability, and thus enteric absorption, would allow for direct enteral delivery at far higher concentrations than would be tolerated systemically, yet retain efficacy.

METHODS

Based on the structure of the angiotensin II type Ia receptor antagonist losartan, deschloro-losartan was synthesized, which has extremely poor cell membrane permeability. Angiotensin II type Ia receptor antagonist efficacy was evaluated by determining the ability to block NF-κB activation in vitro. Dextran sodium sulfate colitis was induced in mice and angiotensin II type Ia receptor antagonist efficacy delivered transanally was assessed.

RESULTS

In vitro, deschloro-losartan demonstrated near equal angiotensin II type Ia receptor blockade compared to losartan as well as another angiotensin II type Ia receptor antagonist, candesartan. In the dextran sodium sulfate model, each compound significantly improved clinical and histologic scores and epithelial cell apoptosis. Abundance of TNF-α, IL-1β, and IL6 mRNA were significantly decreased with each compound. In vitro and in vivo intestinal drug absorption, as well as measures of blood pressure and mucosal and colonic blood flow, showed significantly lower uptake of deschloro-losartan compared to losartan and candesartan.

CONCLUSIONS

This study demonstrated efficacy of high-dose angiotensin II type Ia receptor antagonists in this colitis model. We postulate that a specially designed angiotensin II type Ia receptor antagonist with poor oral absorption may have great potential as a new therapeutic agent for inflammatory bowel disease in the future.

The renin-angiotensin system and the gastrointestinal mucosa

The gastrointestinal (GI) tract is fundamental for the intake of fluid and electrolytes and accommodates a large proportion of bodily hemodynamics and host defence systems. Despite that the renin-angiotensin system (RAS) is a prominent regulatory system for fluid and electrolyte homeostasis its impact on GI physiology is only little explored. Recent data indicate that RAS is well expressed and active in the GI tract although exact physiological roles are to be settled. There are several reports showing influences by RAS and its key mediator angiotensin II (AngII) on intestinal epithelial fluid and electrolyte transport and data are accumulating, suggesting involvement in GI mucosal inflammation and carcinogenesis. Of particular interest is the increasing amount of experimental support for the involvement of AngII formation and actions via the AngII subtype 1 (AT1) receptor in the pathogenesis and treatment of inflammatory bowel disease. The picture of RAS in the GI tract is, however, far from complete. Because RAS is an important application area for reno-cardiovascular diseases, a number of pharmacological agents as well as research technologies already exist and can in the future be used for GI research. A marked expansion of knowledge concerning the role of RAS in GI physiology and pathophysiology is to be expected.

ACE inhibitors and angiotensin II receptor antagonists in Crohn's disease management

An increasing repertoire of therapeutic indications for the angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists has followed an explosion of research exploring the role of the proinflammatory and profibrotic renin-angiotensin-aldosterone system in numerous organ systems. This evidence also implicates the renin-angiotensin-aldosterone system in the pathogenesis of other chronic inflammatory and fibrotic disorders, such as Crohn's disease. While the research to date supports this hypothesis, further investigation of the renin-angiotensin-aldosterone system in human Crohn's disease is required before these agents can realistically be investigated in human trials.

Active crohn disease and hypercalcemia treated with infliximab: case report and literature review

OBJECTIVE

To report a case of 1,25-dihydroxyvitamin D-mediated hypercalcemia caused by active Crohn disease that improved with infliximab therapy.

METHODS

We present the clinical and laboratory findings and describe the clinical course of a patient who had hypercalcemia during Crohn disease exacerbations. The literature is reviewed regarding 1,25-dihydroxyvitamin D production in Crohn disease, and the 3 cases of hypercalcemia in individuals with Crohn disease reported in the literature are described.

RESULTS

A 50-year-old man with long-standing Crohn disease treated with multiple bowel resections presented for take-down ileostomy. He was hypercalcemic and had suppressed parathyroid hormone and parathyroid hormone-related peptide levels. Histopathology of the resected ileostomy site and adjacent small bowel indicated active Crohn disease. Hypercalcemia promptly resolved after a few days of treatment with intravenous glucocorticoids. One month later, hypercalcemia recurred in the presence of an inappropriately high 1,25-dihydroxyvitamin D level and increased urinary calcium and serum angiotensin-converting enzyme levels. The serum and urinary calcium levels became normal with infliximab therapy. Three previous reports of hypercalcemia caused by active Crohn disease describe effective treatment with glucocorticoids. This is the first report of successful response to infliximab in this setting.

CONCLUSION

Hypercalcemia mediated by 1,25-dihydroxyvitamin D in the setting of Crohn disease may respond to glucocorticoid-sparing immunomodulators.

Angiotensin-converting enzyme insertion/deletion gene polymorphism in inflammatory bowel diseases

INTRODUCTION

The renin-angiotensin system is strictly related to the kallikrein-kinin system and both are involved in many physiological and disease conditions and possibly in the pathogenesis of inflammatory bowel disease (IBD). Angiotensin-converting enzyme (ACE) is the pivotal enzyme of the renin-angiotensin system and the main catabolic enzyme of the kallikrein-kinin system. The ACE I/D (insertion/deletion) is a polymorphism of the gene encoding for ACE: participants who are homozygous for the D allele exhibit higher ACE levels, which in turn appear to play a deleterious role in several diseases.

AIM

To study the prevalence of ACE I/D polymorphism in IBD patients and its possible association with disease features.

METHODS

A total of 232 IBD patients, 124 with ulcerative colitis (UC) and 108 with Crohn's disease and 99 healthy controls were genotyped for the ACE I/D polymorphism.

RESULTS

DD, ID and II genotypes distribution did not show significant differences between IBD patients and controls: 42.2 vs. 40.4%, 42.7 vs. 47.5% and 15.1 vs. 12.1%, respectively. No significant difference was observed between Crohn's disease and UC patients. Within UC patients, the presence of DD genotype and the carriage of the D allele were significantly associated with the presence of extraintestinal manifestations: odds ratio (OR) 4.08, 95% confidence interval (CI): 1.62-10.28; P<0.003 and OR=3.07, 95% CI: 1.45-6.48; P<0.003, respectively. No significant association was found with other IBD clinical features.

CONCLUSIONS

The ACE I/D polymorphism is not associated with IBDs but the D allele appears to increase the risk of developing extraintestinal manifestations in UC patients.

The usefulness of angiotensin converting enzyme in the differential diagnosis of Crohn's disease and intestinal tuberculosis

BACKGROUND

Since the pathologic findings of Crohn's disease (CD) and intestinal tuberculosis (IT) overlap to a large degree, the development of other biomarkers will be of great help for making the differential diagnosis of these 2 diseases. The aim of the present study is to examine the clinical efficacy of using the tissue angiotensin converting enzyme (ACE) assay in making the differential diagnosis between CD and IT.

METHODS

Tissue specimens were obtained from 36 patients who were diagnosed with CD or IT by the colonoscopic biopsy, as well as by the clinical findings. The expression of tissue ACE was detected by immunohistochemical staining. The optimal cut-off value of the immunoreactive scoring (IRS) system we used to differentiate CD from IT was determined by analysis of the ROC curve and AUROC.

RESULTS

Granuloma was present in 15 of 19 patients with CD (78.9%) and in 15 of 17 patients with IT (88.2%). ACE was present in the cytoplasm of the epithelioid cells in the granulomas from 13 of 15 patients with CD and in 14 of 15 patients with IT. The IRS scores of ACE were greater in the patients with CD than that of the patients with IT (8.07 +/- 4.38 vs. 4.13 +/- 2.47, respectively, p = 0.006). In differentiating CD from IT, the AUROC curve for the IRS of ACE was 0.767 with a sensitivity of 66.7%, a specificity of 93.3% and the cut-off point was 7.5.

CONCLUSIONS

The results of our study suggest that the assessment of the tissue ACE expression can be helpful for making the differential diagnosis between CD and IT.

Hypercalcemia due to excess 1,25-dihydroxyvitamin D in Crohn's disease

Hypercalcemia has been described in patients with a number of granulomatous diseases, including sarcoidosis and mycobacterial infection. Disordered vitamin D metabolism is the root cause for the elevated serum calcium levels. A similar mechanism of abnormal vitamin D metabolism explained the hypercalcemia occurring in patients with lymphoma. Crohn's disease is a granulomatous disorder that is more commonly associated with hypocalcemia caused by poor calcium intake and decreased intestinal calcium absorption related to vitamin D deficiency as a consequence of malabsorption. A man with Crohn's disease who presented with hypercalcemia and acute renal failure is described. Biochemical parameters showed an elevated 1,25-dihydroxyvitamin D level, with a low-normal 25-hydroxyvitamin D level and decreased parathyroid hormone level. Inflammatory bowel disease had been clinically active during the preceding 2 months. With resolution of gastrointestinal symptoms, serum calcium, vitamin D, and parathyroid hormone levels returned to normal. Serum creatinine levels decreased toward normal. Angiotensin-converting enzyme (ACE) levels have been reported to be elevated in patients with sarcoidosis, particularly in the setting of active disease with hypercalcemia. Controversy exists about ACE levels in the face of active Crohn's disease: 1 report noted elevated levels, whereas other publications reported depressed levels. Our patient had an elevated ACE level in the setting of active bowel disease and hypercalcemia, and ACE levels returned to normal with resolution of gastrointestinal symptoms.

Angiotensin-converting enzyme gene polymorphisms in patients with pulmonary sarcoidosis: impact on disease severity

Angiotensin converting enzyme (ACE) is a metallopeptidase with a key function in the regulation of blood pressure and volume. The ACE1 gene, on chromosome 17, contains a insertion/deletion (I/D) polymorphism in intron 16. The D allele of this polymorphism is linked with raised serum ACE (sACE) levels. Sarcoidosis is a systemic disease of granulomatous inflammation that primarily affects the lung and lymph system. It is often accompanied by elevated sACE related to ACE production from granuloma cells. The ACE I/D polymorphism has been tested for association or linkage with the risk of sarcoidosis. Though published results are conflicting, there seems to be suggestive evidence of a minor pro-inflammatory influence of the ACE D allele in sarcoidosis. At present, a more accurate interpretation of sACE levels in diagnosis and monitoring of sarcoidosis seems to be the main value of ACE I/D genotyping.