19 STROMELYSIN-1 5A/6A AND eNOS T-786C POLYMORPHISMS, MTHFR C677T AND A1298C MUTATIONS, AND CIGARETTE-CANNABIS SMOKING: A PILOT STUDY OF GENE-ENVIRONMENT PATHOPHYSIOLOGICAL ASSOCIATIONS WITH BUERGER'S DISEASE.

Abstract

Buerger's disease (BD) etiologies are poorly understood. Beyond smoking cessation, medical-surgical treatments have limited success. We hypothesized that mutations associated with arterial vasospasm (stromelysin-1 5A/6A, eNOS T-786C) and C677T-A1298C methylenetetrahydrofolate reductase (MTHFR) interacted with cigarette-cannabis smoking, reducing vasodilatory nitric oxide (NO), promoting arterial spasm-thrombosis. Of 19 smoking BD patients (13 men [2 siblings], ± women, 18 Caucasian, 1 African American), compared to 200 healthy Caucasian controls, BD patients were more likely to have 6A6A stromelysin-1 homozygosity (7/19 [37%] vs 46/200 [23%]) and to have eNOS T-786C homozygosity (3/19 [16%] vs 22/200 [11%]), but these patient-control differences were not significant, p = .4, 0.5. C677T MTHFR homozygosity or compound C677T-A1298C heterozygosity did not differ in patients vs controls (6/19 [32%] vs 70/200 [35%]), p = .8. In 9 patients who stopped and 1 who continued smoking, all stromelysin-1 5A/6A and/or eNOS heterozygotes-homozygotes, lower limb gangrenous ulcers, and intractable ischemic rest pain with arterial occlusion progressed despite conventional medical therapy, threatening amputation. In these 10 patients, to increase vasodilatory NO via endothelial NO synthase, L-arginine (15 g/day) was given, along with folic acid 5 mg, vitamin B6 (100 mg), and B12 (2,000 μg/day) to optimize homocysteine metabolism and reduce asymmetric dimethylarginine, a NO synthase inhibitor. Unexpectedly quickly and strikingly, within 8 weeks to 8 months on L-arginine-folic acid, all 10 treated patients improved with uniform pain reduction, ulcer healing, and in 5, full recovery of previously absent peripheral pulses. In smokers homo-heterozygous for stromelysin-1 5A/6A, eNOS T-786C, and C677T-A1298C MTHFR mutations, we speculate that the development and severity of BD are related to a gene-environment vasospastic interaction with reduced NO-mediated vasodilatation. Increasing NO production by L-arginine while optimizing homocysteine metabolism by folic acid-B6-B12 may have therapeutic benefit. Further blinded, placebo-controlled studies are needed to determine whether our observations can be generalized to larger BD cohorts.

Buerger`s Disease and Hyperhomocysteinemia: Is there a Relationship?

“…We can speculate on a pathogenetic role of hyperhomocysteinemia in Buerger's disease but also a secondary increase in homocysteine levels because of the endothelial dysfunction already present in subjects with Buerger's disease cannot be excluded. On the other hand, the relationship with the MTHFR C677T gene variant reported here differs from previous published work [13,14]. Further data are needed in larger populations with a wider ethnic distribution.…”

“…In these reports a role of hyperhomocysteinemia playing a pathogenetic role in Buerger's disease was ruled out, but univocal data are lacking since the majority of reports were based on single case observations or small populations [5,11,12]. On the other hand, reports on the role of MTHFR C677T gene variant, a cause of hyperhomocysteinemia, as a trigger factor of Buerger's disease did not confirm this association [13,14]. Our data showed hyperhomocysteinemia in Buerger's patients that was significant when compared with control subjects.…”

Oxidative and antioxidative pathways might contribute to thromboangiitis obliterans pathophysiology

“…1 The reactive oxygen species in cigarette smoke decrease NO availability through direct elimination or dysfunction of NO biosynthesis (via reduction of tetrahydrobiopterin: BH 4 ), and reduce endothelial nitric oxide synthase (eNOS) activity. 19 However, the occurrence of a mutation in T-786C of the eNOS gene, which has been reported in TAO patients, 15 might augment the effects of oxidative stress from cigarette smoke on NO bioavailability. This might explain the impaired endothelium-dependent vasodilation observed in TAO patients.…”

“…12,13 In addition, hyperhomocysteinemia has been reported in TAO patients in several studies. 14,15 Homocysteine has a strong association with malnutrition. 16 It activates protease-activated receptors and induces production of reactive oxygen species by increasing NADPH oxidase and decreasing thioredoxin expression, and reduces NO bioavailability in cardiac microvascular endothelial cells.…”

Is Rickettsia the key to solving the puzzle of Buerger’s disease?

“…4 Recent studies have demonstrated that nitric oxide (NO) can be protective against Rickettsia infection. 5 Because endothelial nitric oxide synthesis (eNOS) polymorphisms have been reported in BD patients, 6 it could be that smoking dramatically reduces NO bioavailability and helps the spread of Rickettsia infection. This may explain the association of BD with smoking.…”