Kynurenine pathway activation and deviation to anthranilic and kynurenic acid in fibrosing chronic graft-versus-host disease

Fibrosing chronic graft-versus-host disease (cGVHD) is a debilitating complication of allogeneic stem cell transplantation (alloSCT). A driver of fibrosis is the kynurenine (Kyn) pathway, and Kyn metabolism patterns and cytokines may influence cGVHD severity and manifestation (fibrosing versus gastrointestinal [GI] cGVHD). Using a liquid chromatography-tandem mass spectrometry approach on sera obtained from 425 patients with allografts, we identified high CXCL9, high indoleamine-2,3-dioxygenase (IDO) activity, and an activated Kyn pathway as common characteristics in all cGVHD subtypes. Specific Kyn metabolism patterns could be identified for non-severe cGVHD, severe GI cGVHD, and fibrosing cGVHD, respectively. Specifically, fibrosing cGVHD was associated with a distinct pathway shift toward anthranilic and kynurenic acid, correlating with reduced activity of the vitamin-B2-dependent kynurenine monooxygenase, low vitamin B6, and increased interleukin-18. The Kyn metabolite signature is a candidate biomarker for severe fibrosing cGVHD and provides a rationale for translational trials on prophylactic vitamin B2/B6 supplementation for cGVHD prevention.

High IDO activity and an activated Kyn pathway are common in all cGVHD subtypes

Specific Kyn metabolism patterns were identified for gastrointestinal and fibrosing cGVHD

A pathway shift toward anthranilic and kynurenic acid was found in fibrosing cGVHD

A rationale for vitamin B2/B6 adjustment for cGVHD prevention is presented

Exposure of E. coli to DNA-Methylating Agents Impairs Biofilm Formation and Invasion of Eukaryotic Cells via Down Regulation of the N-Acetylneuraminate Lyase NanA

DNA methylation damage can be induced by endogenous and exogenous chemical agents, which has led every living organism to develop suitable response strategies. We investigated protein expression profiles of Escherichia coli upon exposure to the alkylating agent methyl-methane sulfonate (MMS) by differential proteomics. Quantitative proteomic data showed a massive downregulation of enzymes belonging to the glycolytic pathway and fatty acids degradation, strongly suggesting a decrease of energy production. A strong reduction in the expression of the N-acetylneuraminate lyases (NanA) involved in the sialic acid metabolism was also observed. Using a null NanA mutant and DANA, a substrate analog acting as competitive inhibitor, we demonstrated that down regulation of NanA affects biofilm formation and adhesion properties of E. coli MV1161. Exposure to alkylating agents also decreased biofilm formation and bacterial adhesion to Caco-2 eukaryotic cell line by the adherent invasive E. coli (AIEC) strain LF82. Our data showed that methylation stress impairs E. coli adhesion properties and suggest a possible role of NanA in biofilm formation and bacteria host interactions.

Safety and efficacy of thrombolysis with alteplase (50 mg) plus tirofiban versus alteplase (100 mg) alone in acute myocardial infarction: preliminary findings

BACKGROUND

The goal of therapy in acute myocardial infarction (AMI) is the complete and timely restoration of coronary blood flow. Platelets have a pivotal role in the pathophysiology of AMI. The study was aimed at evaluating the safety and efficacy of the combination of 50 mg alteplase plus tirofiban vs 100 mg alteplase in AMI patients.

METHODS

One hundred twenty patients (83 males, 37 females; mean age 54.3 +/- 8 years) were hospitalized for suspected AMI within 6 hours of the onset of symptoms. All patients presented pain and persistent ST-segment elevation, were suitable candidates for thrombolysis (1st episode) and were randomized (double blind) into two groups. Group A (n = 60,42 males, 18 females) received 50 mg alteplase (15 mg as bolus, followed by an infusion of 35 mg over 60 min) in combination with tirofiban (0.4 mcg/kg/min for 30 min followed by an infusion of 0.1 mcg/kg/min for 3 days). Group B (n = 60, 41 males, 19 females) received 100 mg of accelerated-dose alteplase alone. Reperfusion criteria were defined as follows: > 50% reduction in the ST-segment elevation; resolution of chest pain; double marker of creatine kinase (CK) and CK-MB activity 2 hours after the start of thrombolysis; reperfusion arrhythmias within the first 120 min of thrombolysis. The blood pressure, heart rate and ECG were continuously monitored. The mortality, re-AMI, recurrent angina, major and minor bleeding, and emergency bypass surgery or coronary angioplasty were checked.

RESULTS

The groups were similar with regard to clinical data, risk factors, time elapsed from the onset of symptoms to thrombolytic therapy and AMI localization. Forty-seven patients (78.3%) from group A showed reperfusion (15-60 min) vs 25 patients (41.7%) from group B (43-105 min after the end of full-thrombolysis, p = 0.01). Group A patients showed an earlier CK peak and lower CK and CK-MB peaks than those in the control group (p = 0.0001, p = 0.011, p = 0.005, respectively). Nine patients (7.5%) died: 6 (10%) in group B and 3 (5%) in group A (p = NS). A non-fatal re-AMI occurred in 8 patients from group A and in 4 patients from group B (p = NS). Recurrent angina occurred in 27 patients (45%) from group A and in 11 (18.3%) from group B (p = 0.037). Twenty-three of these patients underwent urgent coronary angioplasty (17 from group A and 6 from group B) and 3 from group A and 1 from group B underwent urgent coronary artery bypass grafting (p = NS). The frequency of minor bleeding was higher in group A than in group B (56.7 vs 25%, p = 0.033). No major bleeding was observed in the study groups. At the predischarge echocardiogram, the ejection fraction was higher in group A than in group B (50 +/- 9 vs 44 +/- 7%, p = 0.001).

CONCLUSIONS

Our data suggest that the combination of glycoprotein IIb/IIIa inhibitors plus alteplase is feasible in AMI patients and that the increased risk of bleeding is an acceptable risk considering the advantage in terms of the reduction in the extent of an AMI. In addition, this combination can allow one to gain time when it is necessary to perform mechanical revascularization in patients admitted to a hospital without an interventional cardiology laboratory or in those who have to be referred to another hospital for urgent coronary artery bypass grafting.

Mineralocorticoids and cardiovascular diseases. Status of knowledge from experimental and clinical studies

Although results of randomized trials have demonstrated the beneficial effects of ACE-inhibitors, mortality and morbidity remain high in patients with heart failure and myocardial infarction. In fact, there are data suggesting that aldosterone production may occur despite ACE-inhibitor treatment. There is recent evidence that aldosterone exerts a pro-fibrotic effect, via the mineralocorticoid receptors in cardiovascular tissues resulting in partial aldosterone production during ACE-inhibitor treatment. Mineralocorticoids have also been identified within the cardiovascular system and they may determine increased collagen synthesis which within fibroblasts is largely controlled by locally generated aldosterone. Cardiovascular tissue also expresses genes which are responsible for the late stages of aldosterone and corticosterone formation. Cardiac and vascular tissues elaborate the aforementioned steroids, with the result that aldosterone is more concentrated in the cardiovascular tissue rather than in the circulation. It is probable that locally, while not contributing to the coronary circulation, aldosterone plays an autocrine and/or paracrine role within the tissue of origin. Such roles may relate to local modulation of vessel tonicity and structure, with consequent effects on blood pressure, and repair of damaged tissue through a possible up-regulation of collagen deposition. The ability of the cardiovascular system to elaborate aldosterone opens a vast new area of study since it is becoming increasingly apparent that this local production of mineralocorticoids results in high levels of steroids within the cells of origin and those in the immediate vicinity. The recent RALES trial has shown a significant reduction in mortality, non-fatal hospitalization and sudden death. The fact that patients were on ACE-inhibitors, and accordingly circulating aldosterone levels were presumably reduced, presents the intriguing possibility that spironolactone may block the autocrine and paracrine effects of locally generated aldosterone. This trial has contributed to better understand the pathophysiology of heart failure and its therapeutic strategies. Further studies are required to address this treatment in patients with other heart diseases (hypertension, post-myocardial infarction) and in lower heart failure classes.