The in vivo effect in humans of pyridoxal-5'-phosphate on platelet function and blood coagulation

Significance of Vitamin Supplementation in Reducing the Severity of COVID-19

Coronavirus disease-19 (COVID-19), a serious pandemic due to the SARS-CoV-2 virus infection, caused significant lockdowns, healthcare shortages, and deaths worldwide. The infection leads to an uncontrolled systemic inflammatory response causing severe respiratory distress and multiple-organ failure. Quick development of several vaccines efficiently controlled the spread of COVID-19. However, the rise of various new subvariants of COVID-19 demonstrated some concerns over the efficacy of existing vaccines. Currently, better vaccines to control these variants are still under development as several new subvariants of COVID-19, such as omicron BA-4, BA-5, and BF-7 are still impacting the world. Few antiviral treatments have been shown to control COVID-19 symptoms. Further, control of COVID-19 symptoms has been explored with many natural and synthetic adjuvant compounds in hopes of treating the deadly and contagious disease. Vitamins have been shown to modulate the immune system, function as antioxidants, and reduce the inflammatory response. Recent studies have investigated the potential role of vitamins, specifically vitamins A, B, C, D, and E, in reducing the immune and inflammatory responses and severity of the complication. In this brief article, we discussed our current understanding of the role of vitamins in controlling COVID-19 symptoms and their potential use as adjuvant therapy.

Glucocorticoid-induced thrombotic microangiopathy in paroxysmal nocturnal hemoglobinuria: A case report and review of literature

BACKGROUND

Thrombotic microangiopathy (TMA) is a group of disorders that converge on excessive platelet aggregation in the microvasculature, leading to consumptive thrombocytopenia, microangiopathic hemolysis and ischemic end-organ dysfunction. In predisposed patients, TMA can be triggered by many environmental factors. Glucocorticoids (GCs) can compromise the vascular endothelium. However, GC-associated TMA has rarely been reported, which may be due to the lack of awareness of clinicians. Given the high frequency of thrombocytopenia during GC treatment, particular attention should be given to this potentially fatal complication.

CASE SUMMARY

An elderly Chinese man had a 12-year history of aplastic anemia (AA) and a 3-year history of paroxysmal nocturnal hemoglobinuria (PNH). Three months earlier, methylprednisolone treatment was initiated at 8 mg/d and increased to 20 mg/d to alleviate complement-mediated hemolysis. Following GC treatment, his platelet counts and hemoglobin levels rapidly decreased. After admission to our hospital, the dose of methylprednisolone was increased to 60 mg/d in an attempt to enhance the suppressive effect. However, increasing the GC dose did not alleviate hemolysis, and his cytopenia worsened. Morphological evaluation of the marrow smears revealed increased cellularity with an increased percentage of erythroid progenitors without evident dysplasia. Cluster of differentiation (CD)55 and CD59 expression was significantly decreased on erythrocytes and granulocytes. In the following days, platelet transfusion was required due to severe thrombocytopenia. Observation of platelet transfusion refractoriness indicated that the exacerbated cytopenia may have been caused by the development of TMA due to GC treatment because the transfused platelet concentrates had no defects in glycosylphosphatidylinositol-anchored proteins. We examined blood smears and found a small number of schistocytes, dacryocytes, acanthocytes and target cells. Discontinuation of GC treatment resulted in rapidly increased platelet counts and steady increases in hemoglobin levels. The patient’s platelet counts and hemoglobin levels returned to the levels prior to GC treatment 4 weeks after GC discontinuation.

CONCLUSION

GCs can drive TMA episodes. When thrombocytopenia occurs during GC treatment, TMA should be considered, and GCs should be discontinued.

An overview on role of nutrition on COVID-19 immunity: Accumulative review from available studies

The novel coronavirus infection (COVID-19) conveys a serious global threat to health and economy. A common predisposing factor for development to serious progressive disease is presence of a low-grade inflammation, e.g., as seen in diabetes, metabolic syndrome, and heart failure. Micronutrient deficiencies may also contribute to the development of this state. Therefore, the aim of the present study is to explore the role of the nutrition to relieve progression of COVID-19. According PRISMA protocol, we conducted an online databases search including Scopus, PubMed, Google Scholar and web of science for published literatures in the era of COVID-19 Outbreak regarding to the status of nutrition and COVID-19 until December 2021. There were available studies (80 studies) providing direct evidence regarding the associations between the status of nutrition and COVID-19 infection. Adequate nutritional supply is essential for resistance against other viral infections and also for improvement of immune function and reduction of inflammation. Hence, it is suggested that nutritional intervention which secures an adequate status might protect against the novel coronavirus SARS-CoV-2 (Severe Acute Respiratory Syndrome - coronavirus-2) and mitigate its course. We also recommend initiation of adequate nutritional supplementation in high-risk areas and/or soon after the time of suspected infection with SARS-CoV-2. Subjects in high-risk groups should have high priority for applying this nutritive adjuvant therapy that should be started prior to administration of specific and supportive medical measures.

Antioxidant, anti-inflammatory and immunomodulatory roles of vitamins in COVID-19 therapy

oxidative stress is caused by an abundant generation of reactive oxygen species, associated to a diminished capacity of the endogenous systems of the organism to counteract them. Activation of pro-oxidative pathways and boosting of inflammatory cytokines are always encountered in viral infections, including SARS-CoV-2. So, the importance of counteracting cytokine storm in COVID-19 pathology is highly important, to hamper the immunogenic damage of the endothelium and alveolar membranes. Antioxidants prevent oxidative processes, by impeding radical species generation. It has been proved that vitamin intake lowers oxidative stress markers, alleviates cytokine storm and has a potential role in reducing disease severity, by lowering pro-inflammatory cytokines, hampering hyperinflammation and organ failure. For the approached compounds, direct antiviral roles are also discussed in this review, as these activities encompass secretion of antiviral peptides, modulation of angiotensin-converting enzyme 2 receptor expression and interaction with spike protein, inactivation of furin protease, or inhibition of pathogen replication by nucleic acid impairment induction. Vitamin administration results in beneficial effects. Nevertheless, timing, dosage and mutual influences of these micronutrients should be carefullly regarded.

Inhibition of platelet activation using vitamins

Some vitamins have beneficial effects on cardiovascular diseases, normalizing platelet function and preventing their excess activation. Anti-platelet vitamins can act directly through inhibitory biochemical pathways in platelets or indirectly by preventing damage to the endothelium or low-density lipoprotein from oxidation. As a rule, each vitamin alone is a weak inhibitor of platelet aggregation. However, in combination, they may act synergistically or enhance the effects of endogenous anti-platelet compounds, such as prostacyclin or nitric oxide, and appear to have a sufficient anti-thrombotic effect. This review will focus on vitamins, which inhibit platelet activation and the mechanisms of their action. The relationship between the vitamins that inhibit platelet aggregation and vascular diseases is examined.

B6 and Bleeding: A Case Report of a Novel Vitamin Toxicity

Pyridox(am)ine-5-phosphate oxidase deficiency is an inborn error of vitamin B₆ metabolism that is characterized by neonatal seizures, requiring lifelong therapy with pyridoxal-5-phosphate. We present the first case of a patient with pyridox(am)ine-5-phosphate oxidase deficiency and mild hemophilia A, whose bleeding symptoms were exacerbated by the vitamin B₆ therapy essential for his epileptic disorder. This report expands the spectrum of known vitamin B₆ toxicity and demonstrates a need for vigilance in monitoring for bleeding symptoms in patients requiring pyridoxine or pyridoxal-5-phosphate supplementation.

Vitamin B6 and cardiovascular disease

While overt vitamin B6 deficiency is not a frequent finding nowadays in medical practice, evidence suggests that insufficiency of this vitamin is rather widespread in a quite large portion of the population such as the elderly or in not unusual conditions such as that of alcohol addiction. Moreover, a mild deficiency in B6 vitamin is a state that may be associated with an increased risk of cardiovascular disease. Epidemiologic evidence from case control and prospective studies have suggested that low dietary intake or reduced blood concentrations of vitamin B6 is associated with an increased risk of cardiovascular disease, although most recent trials demonstrated the ineffectiveness of vitamin B6 supplementation on the prevention of cardiovascular events recurrence. Due to limited and somewhat inconsistent data together with the ample variety of critical functions in which vitamin B6 is involved in the human body, it is very challenging to attempt at establishing a cause and effect relationship between vitamin B6 and risk of cardiovascular disease as it is to delineate the exact mechanism(s) by which vitamin B6 may modulate such risk. In the present chapter we review the currently available knowledge deriving from both epidemiological and mechanistic studies designed to define potential candidate mechanisms for the association of vitamin B6 impairment and risk of cardiovascular disease development.

Effect of vitamin B(6) vitamers on platelet aggregation

The vitamers of vitamin B(6) inhibit platelet aggregation. However, their effect is weak when used separately. After the supplementation of one vitamer, the concentrations of the other ones also increase in plasma due to the interconversion of vitamin B(6) forms. It can be suggested that different vitamers in blood can interact with each other. The aim of this work was to test the effect of different vitamer combinations on platelet aggregation in vitro. Platelet aggregation was induced by ADP, collagen or arachidonic acid and measured photometrically in a Chronolog aggregometer. The inhibition of platelet aggregation by the pairwise combinations of the vitamers was significantly stronger than that of each vitamer separately. The combinations of three and four vitamers were yet more effective, inhibiting platelet aggregation at the concentration of 4 microM. Possible involvement of inhibitory prostaglandins in the effect of vitamin B(6) was studied. The inhibition of platelet aggregation by the vitamers could be prevented by the antagonist of prostacyclin receptors, CAY10441 while the antagonist of prostaglandin D(2) receptors, MK 0524 was ineffective. The results suggest that vitamin B(6) vitamers cause a synergistic inhibitory effect on platelet aggregation at concentrations that can be mediated by the activation of prostacyclin receptors with prostaglandin E(1).

Pyridoxine as a template for the design of antiplatelet agents

The B(6) vitamers have been shown to display beneficial therapeutic effects in cardiovascular related disorders. The design of novel antiplatelet agents using pyridoxine as a template has led to the discovery of a class of novel cardio- and cerebro-protective agents. The present study describes the synthesis of several of these derivatives along with the antiplatelet and antiischemic activity of derivative 16.

Opposite effects of nicotinic acid and pyridoxine on systemic prostacyclin, thromboxane and leukotriene production in man

The effects of nicotinic acid (2500 mg orally during 12 hr) and pyridoxine (300 mg orally twice daily for seven days) on the excretion of urinary 2,3-dinor-6-ketoprostaglandin F1alpha, 11-dehydrothromboxane B2 and leukotriene E4, the markers of systemic prostacyclin, thromboxane A2 and cysteinyl leukotriene production, respectively, were investigated in healthy male volunteers (n=6-8). Nicotinic acid increased 11-dehydrothromboxane B2 and leukotriene E4 excretions to 2.6- and 2.0 times the initial values (P<0.05), respectively. In the volunteers treated with pyridoxine, 11-dehydrothromboxane B2 and leukotriene E4 excretions were decreased to 70% (P<0.05) and 65% (P<0.01) of the initial values, respectively, but the excretion of 2,3-dinor-6-ketoprostaglandin F1alpha was increased 1.7 times (P<0.01). The results suggest that nicotinic acid increases thromboxane and leukotriene synthesis which may not be beneficial for patients with cardiovascular diseases or asthma. In contrast, the increase in prostacyclin production and the inhibition in thromboxane and leukotriene synthesis by pyridoxine might be beneficial in disorders where the production of prostacyclin is decreased and the formation of thromboxane and cysteinyl leukotrienes is enhanced.

Low plasma levels of vitamin B(6) are independently associated with a heightened risk of deep-vein thrombosis

BACKGROUND

Elevated plasma levels of total homocysteine (tHcy) before and after an oral methionine load (PML) are associated with an elevated risk of deep-vein thrombosis (DVT). We investigated whether plasma levels of B vitamins that are involved in Hcy metabolism are associated with an elevated risk of DVT.

METHODS AND RESULTS

We compared 397 cases with previous DVT with 585 matched healthy controls. The plasma levels of folate, vitamin B(12), vitamin B(6,), and fasting and PML tHcy were measured. The ORs for DVT associated with high (>95th percentile) fasting levels and PML increases of tHcy were 2.1 (95% CI, 1.2 to 3.4) and 2.4 (95% CI, 1.5 to 3.9) after adjustment for established risk factors for DVT. Fasting plasma levels and PML increases in tHcy correlated negatively with vitamin levels. The crude OR for folate levels in the lowest quartile compared with the highest was 1.5 (95% CI, 1.1 to 2.1), and that for B(6) levels in the lowest and second quartiles compared with the highest was 1.5 (95% CI, 1.0 to 2.1). However, after adjustment for established risk factors and fasting and PML tHcy, the ORs for B(6) levels in the lowest and second quartiles only remained statistically significant (lowest quartile: OR, 1.8; 95% CI, 1.2 to 2.8; second quartile, OR, 1.9; 95% CI, 1.3 to 2.9).

CONCLUSIONS

High fasting and PML tHcy and low vitamin B(6) plasma levels are associated with an elevated risk for DVT independently of established risk factors for DVT. The association of low vitamin B(6) levels with the risk for DVT is independent of fasting and PML tHcy levels.

Nicotinic acid and pyridoxine modulate arachidonic acid metabolism in vitro and ex vivo in man

The in vitro effects of nicotinic acid (10-1000 microM), pyridoxine (0.1-500 microM) and pyridoxal-5'-phosphate (0.1-500 microM) and the ex vivo effects of nicotinic acid (2500 mg orally during 12 h) and pyridoxine (600 mg orally daily for seven days) on arachidonic acid metabolism were investigated in calcium ionophore A23187 (calcimycin)-stimulated human whole blood. In vitro nicotinic acid stimulated prostaglandin E2, thromboxane B2 and leukotriene E4 synthesis. Pyridoxine at all concentrations and pyridoxal-5'-phosphate at the highest concentration stimulated prostaglandin E2 and thromboxane B2 production, but had no effect on leukotriene E4 synthesis. Nicotinic acid treatment increased ex vivo prostaglandin E2, thromboxane B2 and leukotriene E4 synthesis to 185%, 165% and 175% of the initial values, respectively. In the pyridoxine-treated subjects, ex vivo prostaglandin E2, thromboxane B2 and leukotriene E4 synthesis was decreased after seven days to 75%, 65% and 45% of the initial values, respectively. In the present study the effects of nicotinic acid on the 5-lipoxygenase pathway in arachidonic acid metabolism were studied for the first time and the drug was found to stimulate this pathway in vitro and ex vivo. In vitro pyridoxine and pyridoxal-5'-phosphate had no effect on the 5-lipoxygenase pathway. The inhibition of leukotriene synthesis by pyridoxine ex vivo might be of therapeutic importance.