Abnormal vitamin B6 status in rheumatoid cachexia. Association with spontaneous tumor necrosis factor alpha production and markers of inflammation

Vitamin B6 ameliorates acute pancreatitis by suppressing the caspase3 signaling pathway

BACKGROUND

Acute pancreatitis (AP) is a prevalent exocrine inflammatory disorder of the pancreas characterized by pancreatic inflammation and injury to acinar cells. Vitamin B6 (VB6) is a vital nutrient that plays a significant role in preserving human health and has anti-inflammatory and anti-apoptotic effects.

METHODS

This study aimed to explore the potential pancreatic protective effects of VB6 in mitigating pancreatic inflammation and apoptosis induced by taurocholate sodium (TLCS) in an AP model and to assess the underlying mechanism of action. AP was induced in Sprague‒Dawley (SD) rats through TLCS administration and lipopolysaccharide (LPS)-treated AR42J cells, followed by treatment with VB6.

RESULTS

Various parameters associated with AP were assessed in both plasma and pancreatic tissues. VB6 has been shown to ameliorate the severity of AP through various mechanisms. It effectively reduces the levels of serum amylase, lipase, and inflammatory factors, thereby mitigating histological injury to the pancreas. Moreover, VB6 inhibited pancreatic apoptosis by downregulating bax expression and up-regulating Bcl2 expression in TLCS-treated rats. Additionally, VB6 suppressed the expression of caspase3. The anti-inflammatory and anti-apoptotic effects of VB6 observed in LPS-treated AR42J cells are consistent with those observed in a rat model of AP.

CONCLUSIONS

These results suggest that VB6 exerts anti-inflammatory and anti-apoptotic effects through inhibition of the caspase3 signaling pathway and has a protective effect against AP.

Transsulfuration and folate pathways in rheumatoid arthritis: A systematic review and meta-analysis

BACKGROUND

Metabolomic assessment of the transsulfuration and folic acid biochemical pathways could lead to the identification of promising biomarkers of nitric oxide dysregulation and oxidative stress in rheumatoid arthritis (RA).

METHODS

We conducted a systematic review and meta-analysis of transsulfuration (methionine, homocysteine, and cysteine) and folic acid (folic acid, vitamin B6 , and vitamin B12 ) metabolites in RA patients in remission and healthy controls. Electronic databases were searched from inception to 15 July 2023 for relevant articles. We assessed the risk of bias using the JBI checklist and the certainty of evidence using GRADE.

RESULTS

In 28 eligible studies, compared to controls, RA patients had significantly higher concentrations of homocysteine (standardized mean difference, SMD = 0.74, 95% CI 0.54-0.93, p < 0.001; low certainty of evidence) and methionine (SMD = 1.00, 95% CI 0.57-1.44, p < 0.001; low certainty) and lower concentrations of vitamin B6 (SMD = -6.62, 95% CI -9.65 to -3.60, p < 0.001; low certainty). By contrast, there were non-significant between-group differences in vitamin B12 and folic acid. In meta-regression and subgroup analysis, there were no associations between the effect size and several study and patient characteristics except for homocysteine (year of publication, C-reactive protein, triglycerides, and analytical method) and folic acid (biological matrix).

CONCLUSIONS

The results of our study suggest that homocysteine, methionine, and vitamin B6 are promising biomarkers to assess nitric oxide dysregulation and oxidative stress in RA. (PROSPERO registration number: CRD42023461081).

Factors influencing vitamin B6 status in domestic cats: age, disease, and body condition score

Limited studies are available on vitamin B6 status in domestic cats. To this end, we evaluated glutamate-oxaloacetate transaminase (GOT) activity in hemolysates with and without pyridoxal 5'-phosphate addition in two feline populations: a cohort of 60 healthy, domestic (sexually intact and specific pathogen-free) cats maintained under strictly controlled conditions with appropriate diets housed at the Feline Nutrition and Pet Care Center, and a cohort of 57 cats randomly selected between December 2022 to January 2023 that visited the Veterinary Medicine Teaching Hospital to seek care under different circumstances. The GOT activity expressed as the ratio with and without pyridoxal 5'-phosphate addition (primary activation ratio; PAR) decreased significantly with age in the healthy cohort. The PAR values normalized to age established a cut-off for vitamin B6 deficiency in both cohorts, identifying 17 of 101 animals as vitamin B6 deficient. Using machine learning, a partition-based model (decision tree) was built to identify the most important factors that predicted vitamin B6 deficiency while using the resulting tree to make predictions for new observations. This analysis, performed with all 101 cats, revealed that the diagnosis of an infectious, chronic or acute condition (0.55) was the main contributor, followed by age (0.26), and body condition score (optimal-overweight; 0.19). Thus, our study supports that vitamin B6 supplementation may be indicated in junior to adult animals diagnosed with an infectious, chronic, or acute conditions or healthy cats with body weight ranging from optimal to overweight. In older cats, even if healthy, underweight to optimal cats appear to be at risk of vitamin B6 deficiency.

A retrospective analysis of vitamin B6 deficiency and associated changes of gut microbes in Crohn's disease

BACKGROUND

Patients with inflammatory bowel diseases (IBD) are at risk of micronutrient deficiencies, particularly during flares. Vitamin B6 is required for the proper development of brain, nerves, and many other parts of the body. However, limited studies are available to describe the prevalence, relevance and consequences of vitamin B6 deficiencies in IBD. We aim to estimate the prevalence of vitamin B6 deficiencies in Crohn's disease (CD) patients, to identify associated risk factors and to explore the alteration of intestinal microbiota related to vitamin B6 status.

METHODS

A total of 360 CD patients and 55 ulcerative colitis (UC) patients from Shanghai Tenth People's Hospital of Tongji University were included. Serum vitamin B6 concentrations were collected from the computerized laboratory data. The logistic regression was used for statistical analysis. Fecal-associated microbiota was also analyzed using 16S rRNA sequencing in another 20 CD patients (10 of vitamin B6 normal, 10 of vitamin B6 deficiency).

RESULTS

The prevalence of vitamin B6 abnormality was significantly higher in CD than in UC patients. Logistic regression analysis showed that small bowel lesion, ileocolonic lesion (L3), extraintestinal manifestations, ileal resection, and usage of immunosuppressor were independently associated with abnormal vitamin B6 in CD. Interestingly, the microbial structure presented significant differences between two CD groups. PICRUSt2 prediction revealed that some enzymes and metabolic pathways between the two groups were significantly different.

CONCLUSIONS

Collectively, our analysis showed that vitamin B6 reduction occurred frequently in patients with CD and affected the intestinal flora of patients.

Impact of lifestyle factors on dietary vitamin B6 intake and plasma pyridoxal 5'-phosphate level in UK adults: National Diet and Nutrition Survey Rolling Programme (NDNS) (2008-2017)

Reduction in dietary vitamin B6 intake is associated with an increased relative risk of diseases such as cancer, atherosclerosis and cognitive dysfunction. The current research has assessed vitamin B6 intakes and PLP concentrations as a marker of vitamin B6 status among the UK adult (≥ 19 years) population. This study was carried out using a cross-sectional analysis of the National Diet and Nutrition Survey Rolling Programme (NDNS) (2008-2017). The impacts of lifestyle factors, including type of diet, smoking, alcohol consumption, and commonly used medications grouped by therapeutic usage, were determined, and data were analysed using IBM SPSS®. Results are expressed as medians (25th-75th percentiles), with P values ≤ 0·05 considered statistically significant. Among UK adults, the median intakes of total population of dietary vitamin B6 met the reference nutrient intake and median plasma PLP concentrations were above the cut-off of vitamin B6 deficiency; however, we found an association between reduction in vitamin B6 intake and plasma PLP concentration and age group (P < 0·001). Smokers had significantly lower plasma PLP concentrations than non-smokers (P < 0·001). Moreover, regression analysis showed some commonly used medications were associated with plasma PLP levels reduction (P < 0·05). Taken together, we report on a tendency for dietary vitamin B6 intake and plasma PLP concentrations to decrease with age and lifestyle factors such as smoking and medication usage. This information could have important implications for smokers and in the elderly population using multiple medications (polypharmacy).

Clinical and biochemical impact of vitamin B6 deficiency in primary sclerosing cholangitis before and after liver transplantation

BACKGROUND AND AIMS

We previously demonstrated that people with primary sclerosing cholangitis (PSC) had reduced gut microbial capacity to produce active vitamin B6 (pyridoxal 5'-phosphate [PLP]), which corresponded to lower circulating PLP levels and poor outcomes. Here, we define the extent and biochemical and clinical impact of vitamin B6 deficiency in people with PSC from several centers before and after liver transplantation (LT).

METHODS

We used targeted liquid chromatography-tandem mass spectrometry to measure B6 vitamers and B6-related metabolic changes in blood from geographically distinct cross-sectional cohorts totaling 373 people with PSC and 100 healthy controls to expand on our earlier findings. Furthermore, we included a longitudinal PSC cohort (n = 158) sampled prior to and serially after LT, and cohorts of people with inflammatory bowel disease (IBD) without PSC (n = 51) or with primary biliary cholangitis (PBC) (n = 100), as disease controls. We used Cox regression to measure the added value of PLP to predict outcomes before and after LT.

RESULTS

In different cohorts, 17-38% of people with PSC had PLP levels below the biochemical definition of a vitamin B6 deficiency. The deficiency was more pronounced in PSC than in IBD without PSC and PBC. Reduced PLP was associated with dysregulation of PLP-dependent pathways. The low B6 status largely persisted after LT. Low PLP independently predicted reduced LT-free survival in both non-transplanted people with PSC and in transplant recipients with recurrent disease.

CONCLUSIONS

Low vitamin B6 status with associated metabolic dysregulation is a persistent feature of PSC. PLP was a strong prognostic biomarker for LT-free survival both in PSC and recurrent disease. Our findings suggest that vitamin B6 deficiency modifies the disease and provides a rationale for assessing B6 status and testing supplementation.

IMPACT AND IMPLICATIONS

We previously found that people with PSC had reduced gut microbial potential to produce essential nutrients. Across several cohorts, we find that the majority of people with PSC are either vitamin B6 deficient or have a marginal deficiency, which remains prevalent even after liver transplantation. Low vitamin B6 levels strongly associate with reduced liver transplantation-free survival as well as deficits in biochemical pathways dependent on vitamin B6, suggesting that the deficiency has a clinical impact on the disease. The results provide a rationale for measuring vitamin B6 and to investigate whether vitamin B6 supplementation or modification of the gut microbial community can help improve outcomes for people with PSC.

Associations of vitamin B6 turnover rate with the risk of cardiovascular and all-cause mortality in hypertensive adults

BACKGROUND AND AIM

This study was to assess the association between vitamin B6 turnover rate and mortality in hypertensive adults.

METHODS AND RESULTS

Vitamin B6 status including serum pyridoxal-5'-phosphate (PLP) levels, serum 4-pyridoxal acid (4-PA) levels, and vitamin B6 turnover rate (4-PA/PLP) were obtained from the 2005-2010 National Health and Nutrition Examination Survey (NHANES) dataset of hypertensive adults with follow-up through December 30, 2019. Using Cox proportional risk regression models, Hazard ratios (HRs) and 95% confidence intervals (CIs) were analyzed for PLP, 4-PA and 4-PA/PLP quartiles in relation to cardiovascular and all-cause mortality. A total of 5434 participants were included in this study (mean age, 58.48 years; 50.4% men), and the median 4-PA/PLP was 0.75. The median follow-up time was 11.0 years, with 375 and 1387 cardiovascular and all-cause deaths, respectively. In multivariate COX regression models, PLP was negatively associated with cardiovascular mortality (HR [95% CI] quartile 4 vs. 1: 0.66 [0.47-0.94], P_trend = 0.03) and 4-PA/PLP was positively associated with cardiovascular mortality (HR [95% CI] quartile 4 vs.1: 1.80 [1.21-2.67], P_trend = 0.01). Similarly, the higher the quartile of PLP, the lower the risk of all-cause mortality (HR [95% CI] quartile 4 vs. 1: 0.67 [0.56-0.80], P_trend < 0.01). The higher the quartile of 4-PA and 4-PA/PLP, the higher the risk of all-cause mortality (HR [95% CI] quartile 4 vs. 1: 1.22 [1.01-1.48], P_trend < 0.01; and 2.09 [1.71-2.55], P_trend < 0.01).

CONCLUSION

The findings suggested that higher vitamin B6 turnover rate was associated with an increased risk of cardiovascular and all-cause mortality in hypertensive adults.

Variation of homocysteine levels in rheumatoid arthritis patients: relationship to inflammation, cardiovascular risk factors, and methotrexate

BACKGROUND

The aim of this study was to evaluate the variation of homocysteine (Hcy) levels in patients with rheumatoid arthritis (RA) and to analyze the relationship to inflammatory parameters, cardiovascular risk, and methotrexate (MTX).

METHODS

This cross-sectional study assessed disease activity and treatment in RA patients. The European League Against Rheumatism (EULAR) 2015 HeartSCORE was performed for cardiovascular (CV) risk estimation and levels of plasma Hcy, serum folate concentrations, vitamin B12, and erythrocyte sedimentation rate (ESR) were measured.

RESULTS

A total of 103 participants with mean age 53 ± 10 years and mean disease duration 10.55 ± 7.34 years were included. Patients were treated with MTX in 69.9% of cases and corticosteroid in 80.5% of cases. Of all patients, 13% had a cardiovascular inheritance, 25% were hypertensive, and 18% had diabetes. The EULAR 2015 HeartSCORE was high and very high (≥5%) in 35% of cases. Mean Hcy level was 12.54 ± 4.2 µmol/L [6.89-32.92] and hyperhomocysteinemia was noted in 20.4% of patients. Analytic study demonstrated that hyperhomocysteinemia was associated with male gender (p = 0.01), MTX use (p = 0.01), smoking (p = 0.008), renal failure (p = 0.04), and high disease activity (p = 0.05), but there was no association with the HeartSCORE (p = 0.23). Hcy level was negatively correlated with folate (p = 0.009) and vitamin B12 level (p = 0.02) and positively with age (p = 0.01), C‑reactive protein (CRP; p = 0.05), and Simplified Disease Activity Index (SDAI; p = 0.03). In multivariate logistic regression analysis, current MTX use, levels of vitamin B12 and creatine, and Clinical Disease Activity Index (CDAI) appeared to be independent factors associated with hyperhomocysteinemia.

CONCLUSION

MTX use, CDAI, and the levels of vitamin B12 and creatine are independent factors associated with hyperhomocysteinemia.

What We Know So Far about the Metabolite-Mediated Microbiota-Intestinal Immunity Dialogue and How to Hear the Sound of This Crosstalk

Trillions of microorganisms, termed the "microbiota", reside in the mammalian gastrointestinal tract, and collectively participate in regulating the host phenotype. It is now clear that the gut microbiota, metabolites, and intestinal immune function are correlated, and that alterations of the complex and dynamic host-microbiota interactions can have deep consequences for host health. However, the mechanisms by which the immune system regulates the microbiota and by which the microbiota shapes host immunity are still not fully understood. This article discusses the contribution of metabolites in the crosstalk between gut microbiota and immune cells. The identification of key metabolites having a causal effect on immune responses and of the mechanisms involved can contribute to a deeper insight into host-microorganism relationships. This will allow a better understanding of the correlation between dysbiosis, microbial-based dysmetabolism, and pathogenesis, thus creating opportunities to develop microbiota-based therapeutics to improve human health. In particular, we systematically review the role of soluble and membrane-bound microbial metabolites in modulating host immunity in the gut, and of immune cells-derived metabolites affecting the microbiota, while discussing evidence of the bidirectional impact of this crosstalk. Furthermore, we discuss the potential strategies to hear the sound of such metabolite-mediated crosstalk.

Compound amino acid combined with high-dose vitamin B6 attenuate traumatic coagulopathy via inhibiting inflammation by HMGB1/TLR4/NF-κB pathway

BACKGROUND

Traumatic coagulopathy (TC) arises primarily from coagulation system failure to maintain adequate hemostasis after serious blood loss or trauma. Circulatory homeostasis restoration is the mainstay of the therapeutic approach to TC, but the effects are significantly inhibited by coagulopathy.

OBJECTIVE

To identify the therapeutic effects and underlying mechanism of compound amino acid (CAA) combined with high-dosage of vitamin B6 (VB6) on TC.

METHODS

Rabbit traumatic model and cellular model were used to evaluate the effect of CAA combined with high-dosage of VB6 in TC. Blood concentrations of AST and ALT were measured using the Vitros 250 device while blood APTT, PT and TT concentrations were measured using commercial diagnostics kits. Furthermore, qRT-PCR, ELISA and Western blotting were used to determine the expression of clotting factor (II, VII, IX, X and XI), inflammatory factors (TNF-α, IL-6 and IL-1β) and HMGB1/TLR4/NF-κB signaling-related proteins, respectively.

RESULTS

In the rabbit traumatic model, CAA combined with high-dosage of VB6 therapy inhibited the high expression of AST and ALT, but increased the expression of coagulation factors. Additionally, in both the rabbit trauma model and cellular injury model, CAA combined with high-dosage of VB6 inhibited the expression of inflammatory factors (IL-6, TNF-α and IL-1β) and proteins (HMGB1, TLR4 and p-p65) in HMGB1/TLR4/NF-κB pathway. Most importantly, over-expression of HMGB1 reversed the effect of CAA and VB6 in HUVECs and EA.hy926 cells injury model.

CONCLUSION

CAA combined with high-dosage of VB6 alleviated TC and inhibited the expression and secretion of inflammatory factors by inhibiting HMGB1-mediated TLR4/NF-κB pathway.

Significantly Elevated Levels of Plasma Nicotinamide, Pyridoxal, and Pyridoxamine Phosphate Levels in Obese Emirati Population: A Cross-Sectional Study

Water-soluble vitamins like B3 (nicotinamide), B6 (pyridoxine), and B9 (folic acid) are of utmost importance in human health and disease, as they are involved in numerous critical metabolic reactions. Not surprisingly, deficiencies of these vitamins have been linked to various disease states. Unfortunately, not much is known about the physiological levels of B6 vitamers and vitamin B3 in an ethnically isolated group (such as an Emirati population), as well as their relationship with obesity. The aim of the present study was to quantify various B6 vitamers, as well as B3, in the plasma of obese and healthy Emirati populations and to examine their correlation with obesity. A sensitive and robust HPLC-MS/MS-based method was developed for the simultaneous quantitation of five physiologically relevant forms of vitamin B6, namely pyridoxal, pyridoxine, pyridoxamine, pyridoxamine phosphate, and pyridoxal phosphate, as well as nicotinamide, in human plasma. This method was used to quantify the concentrations of these vitamers in the plasma of 57 healthy and 57 obese Emirati volunteers. Our analysis showed that the plasma concentrations of nicotinamide, pyridoxal, and pyridoxamine phosphate in the obese Emirati population were significantly higher than those in healthy volunteers (p < 0.0001, p = 0.0006, and p = 0.002, respectively). No significant differences were observed for the plasma concentrations of pyridoxine and pyridoxal phosphate. Furthermore, the concentrations of some of these vitamers in healthy Emirati volunteers were significantly different than those published in the literature for Western populations, such as American and European volunteers. This initial study underscores the need to quantify micronutrients in distinct ethnic groups, as well as people suffering from chronic metabolic disorders.

The vitamin B6-regulated enzymes PYGL and G6PD fuel NADPH oxidases to promote skin inflammation

Psoriasis is a skin inflammatory disorder that affects 3% of the human population. Although several therapies based on the neutralization of proinflammatory cytokines have been used with relative success, additional treatments are required. The in silico analysis of gene expression data of psoriasis lesional skin and an analysis of vitamin B6 metabolites in the sera of psoriasis patients point to altered vitamin B6 metabolism at both local and systemic levels. Functional studies showed that vitamin B6 vitamers reduced skin neutrophil infiltration, oxidative stress and Nfkb activity in two zebrafish models of skin inflammation. Strikingly, inhibition of glycogen phosphorylase L (Pygl) and glucose-6-phosphate dehydrogenase (G6pd), two vitamin B6-regulated enzymes, alleviated oxidative-stress induced inflammation in zebrafish skin inflammation models. Despite the central role of G6pd in antioxidant defenses, the results of the study demonstrate that glycogen stores and G6pd fuel NADPH oxidase to promote skin inflammation, revealing novel targets for the treatment of skin inflammatory disorders.

Physical Activity Prevents Cartilage Degradation: A Metabolomics Study Pinpoints the Involvement of Vitamin B6

Osteoarthritis (OA) is predominantly characterized by the progressive degradation of articular cartilage, the connective tissue produced by chondrocytes, due to an imbalance between anabolic and catabolic processes. In addition, physical activity (PA) is recognized as an important tool for counteracting OA. To evaluate PA effects on the chondrocyte lineage, we analyzed the expression of SOX9, COL2A1, and COMP in circulating progenitor cells following a half marathon (HM) performance. Therefore, we studied in-depth the involvement of metabolites affecting chondrocyte lineage, and we compared the metabolomic profile associated with PA by analyzing runners’ sera before and after HM performance. Interestingly, this study highlighted that metabolites involved in vitamin B6 salvage, such as pyridoxal 5′-phosphate and pyridoxamine 5′-phosphate, were highly modulated. To evaluate the effects of vitamin B6 in cartilage cells, we treated differentiated mesenchymal stem cells and the SW1353 chondrosarcoma cell line with vitamin B6 in the presence of IL1β, the inflammatory cytokine involved in OA. Our study describes, for the first time, the modulation of the vitamin B6 salvage pathway following PA and suggests a protective role of PA in OA through modulation of this pathway.

Vitamin B-6 Status Correlates with Disease Activity in Rheumatoid Arthritis Patients During Treatment with TNFα Inhibitors

BACKGROUND

A frequent observation in inflammatory conditions, including rheumatoid arthritis (RA), is low circulating amounts of pyridoxal 5'-phosphate (PLP), the metabolically active form of vitamin B-6. Recently, a functional marker of vitamin B-6 status, the ratio of 3-hydroxykynurenine (HK): xanthurenic acid (XA) in plasma (HK: XA), was proposed.

OBJECTIVE

We investigated vitamin B-6 status in patients with RA before and after established treatment with TNFα inhibitors.

METHODS

We performed a longitudinal study of RA patients (n = 106, 36% men, median age 54 y) starting first treatment with a TNFα inhibitor (infliximab, etanercept, adalimumab, golimumab, or certolizumab). Clinical assessment (Disease Activity Score for 28 standard joints, DAS28), joint ultrasonography, and blood draw were performed at baseline and after 3 mo treatment. Plasma concentrations of PLP, HK, and XA were measured by liquid chromatography-tandem mass spectrometry. Associations of changes in vitamin B-6 markers with change in DAS28 were assessed by generalized additive models regression and with European League Against Rheumatism (EULAR) response categories by linear regression.

RESULTS

At baseline PLP was inversely correlated with CRP (ρ = -0.27, P = 0.007), whereas HK: XA correlated with DAS28 (ρ = 0.46, P < 0.001), CRP (ρ = 0.36, P < 0.001), and ultrasonography scores (ρ = 0.29-0.35, P ≤ 0.003). After 3 mo treatment, the change (a 33% overall reduction) in DAS28 was related to changes in both PLP (ß = -0.28, P = 0.01) and HK: XA (ß = 0.33, P < 0.001). Good responders (45%) according to EULAR criteria experienced a 31% increase in PLP (P = 0.003) and an 11% decrease in HK: XA (P = 0.1), whereas nonresponders (24%) experienced a 25% increase in HK: XA (P = 0.02).

CONCLUSION

Two independent measures of vitamin B-6 status confirm an association with disease activity in RA patients. The association of HK: XA with disease activity may also imply perturbations in kynurenine metabolism in RA. This trial was registered at helseforskning.etikkom.no as 2011/490.

Inflammation, vitamin B6 and related pathways

The active form of vitamin B6, pyridoxal 5'-phosphate (PLP), serves as a co-factor in more than 150 enzymatic reactions. Plasma PLP has consistently been shown to be low in inflammatory conditions; there is a parallel reduction in liver PLP, but minor changes in erythrocyte and muscle PLP and in functional vitamin B6 biomarkers. Plasma PLP also predicts the risk of chronic diseases like cardiovascular disease and some cancers, and is inversely associated with numerous inflammatory markers in clinical and population-based studies. Vitamin B6 intake and supplementation improve some immune functions in vitamin B6-deficient humans and experimental animals. A possible mechanism involved is mobilization of vitamin B6 to the sites of inflammation where it may serve as a co-factor in pathways producing metabolites with immunomodulating effects. Relevant vitamin B6-dependent inflammatory pathways include vitamin B6 catabolism, the kynurenine pathway, sphingosine 1-phosphate metabolism, the transsulfuration pathway, and serine and glycine metabolism.

Serum Immune System Biomarkers Neopterin and Interleukin-10 Are Strongly Related to Tryptophan Metabolism in Healthy Young Adults

BACKGROUND

Changes in tryptophan metabolism through the vitamin B-6-dependent kynurenine pathway have been linked to activation of the immune system.

OBJECTIVE

We hypothesized that blood concentrations of tryptophan and its catabolites were associated with biomarkers relevant to inflammatory processes in healthy noninflamed subjects.

METHODS

Healthy young adults (n = 737) aged 18-28 y without any known diseases or clinical evidence of inflammation provided blood samples for analysis of serum tryptophan/kynurenine metabolites, neopterin, C-reactive protein (CRP), and plasma pyridoxal 5'-phosphate (PLP) with LC-tandem mass spectrometry methodologies. A panel of cytokines was measured in serum by using high-sensitivity ELISA assays. Anthropometric and lifestyle data were collected by questionnaire. Multiple linear regression analysis to determine the effect of measured serum cytokine concentrations as predictors of tryptophan metabolites was performed on inverse normal-rank transformations of the data, adjusted for sex, body mass index, smoking, alcohol intake, and contraceptive use in women.

RESULTS

Median serum CRP and neopterin concentrations were well below established clinical cutoffs for inflammation. We observed significant positive associations between serum interleukin-10 (IL-10) and serum kynurenine (P = 0.0002), the kynurenine-to-tryptophan ratio (KTR) (P = 0.003), 3-hydroxykynurenine (P = 0.01), and 3-hydroxyanthranilic acid (P = 0.04). Serum neopterin was positively associated with kynurenine, the KTR (both P < 0.0001), and anthranilic acid (P = 0.004), and was negatively associated with serum tryptophan (P = 0.01) and PLP (P < 0.0001). Serum tumor necrosis factor α was also negatively associated with tryptophan (P < 0.001).

CONCLUSIONS

In healthy young adults with no apparent inflammatory conditions, serum tryptophan metabolites are significantly associated with key immune system biomarkers. The observed association between IL-10 and kynurenine is unexpected and suggests that kynurenine-linked mechanisms promoting negative regulation of inflammatory responses are associated with normal immune homeostasis.

Dietary B Vitamins and Serum C-Reactive Protein in Persons With Human Immunodeficiency Virus Infection: The Positive Living With HIV (POLH) Study

BACKGROUND

B vitamins may have beneficial roles in reducing inflammation; however, research on the role of B vitamins in inflammation among HIV-infected persons is lacking.

OBJECTIVE

This study assessed the association between B vitamins and serum C-reactive protein (CRP) concentrations in HIV-infected persons.

METHODS

A cross-sectional survey was conducted among 314 HIV-infected persons (180 men and 134 women) aged 18 to 60 years residing in the Kathmandu, Nepal. High-sensitive and regular serum CRP concentrations were measured by the latex agglutination nephelometry and latex agglutination turbidimetric method, respectively. Dietary intake was assessed using 2 nonconsecutive 24-hour dietary recalls. The relationships between B vitamins and serum CRP concentrations were assessed using multiple regression analysis.

RESULTS

The multivariate-adjusted geometric mean of serum CRP concentrations was significantly decreased with an increasing B vitamins intake across quartiles of niacin (P for trend = .007), pyridoxine (P for trend = .042), and cobalamin (P for trend = .037) in men. In men, the mean serum CRP concentrations in the highest quartiles of niacin, pyridoxine, and cobalamin were 63%, 38%, and 58%, respectively, lower than that in the lowest quartile. In women, the mean serum CRP concentrations in the highest quartiles of riboflavin (P for trend = .084) and pyridoxine (P for trend = .093) were 37% and 47%, respectively, lower than that in the lowest quartile.

CONCLUSION

High intake of niacin, pyridoxine, or cobalamin was independently associated with decreased serum CRP concentrations among HIV-infected men. Further prospective studies are warranted to confirm the role of B vitamins in inflammation among HIV-infected persons.

F11R mRNA expression and promoter polymorphisms in patients with rheumatoid arthritis

AIM

Although F11 receptor (F11R), also named junctional adhesion molecular A (JAM-A), participates in leukocyte migration, its role in autoimmune diseases has not been specifically disclosed. In this study, we examined the association of F11R expression with the development and clinical manifestations of rheumatoid arthritis (RA).

METHOD

RNA from peripheral blood mononuclear cells (PBMCs) and DNA from the peripheral blood in RA patients and a healthy control group were extracted. F11R messenger RNA (mRNA) expression was determined by quantitative real-time polymerase chain reaction. The F11R polymorphisms were determined by the TaqMan genotyping assay.

RESULTS

There was more F11R mRNA expression in the PBMCs of RA patients than those of the control group (P = 0.018). In F11R promoter -688 A > C, C carriers have lower titers of the anticyclic citrullinated peptide (anti-CCP) antibodies (P = 0.002) and fewer positive rates of Schirmer's tests (P = 0.009). The effect is independent of the existence of HLA-DR4. Different genotypes in F11R promoter -688 A > C and -436 A > G do not lead to changes of the gene expression in RA patients.

CONCLUSION

RA patients have higher mRNA expression of F11R. In RA patients, F11R -688 C may be a protective factor for the development of anti-CCP antibodies and positive rates of Schirmer's tests.

Direct and Functional Biomarkers of Vitamin B6 Status

Measures of B6 status are categorized as direct biomarkers and as functional biomarkers. Direct biomarkers measure B6 vitamers in plasma/serum, urine and erythrocytes, and among these plasma pyridoxal 5'-phosphate (PLP) is most commonly used. Functional biomarkers include erythrocyte transaminase activities and, more recently, plasma levels of metabolites involved in PLP-dependent reactions, such as the kynurenine pathway, one-carbon metabolism, transsulfuration (cystathionine), and glycine decarboxylation (serine and glycine). Vitamin B6 status is best assessed by using a combination of biomarkers because of the influence of potential confounders, such as inflammation, alkaline phosphatase activity, low serum albumin, renal function, and inorganic phosphate. Ratios between substrate-products pairs have recently been investigated as a strategy to attenuate such influence. These efforts have provided promising new markers such as the PAr index, the 3-hydroxykynurenine:xanthurenic acid ratio, and the oxoglutarate:glutamate ratio. Targeted metabolic profiling or untargeted metabolomics based on mass spectrometry allow the simultaneous quantification of a large number of metabolites, which are currently evaluated as functional biomarkers, using data reduction statistics.

Biomarkers of one-carbon metabolism are associated with biomarkers of inflammation in women

Folate-mediated one-carbon metabolism is essential for DNA synthesis, repair, and methylation. Perturbations in one-carbon metabolism have been implicated in increased risk of some cancers and may also affect inflammatory processes. We investigated these interrelated pathways to understand their relation. The objective was to explore associations between inflammation and biomarkers of nutritional status and one-carbon metabolism. In a cross-sectional study in 1976 women selected from the Women's Health Initiative Observational Study, plasma vitamin B-6 [pyridoxal-5'-phosphate (PLP)], plasma vitamin B-12, plasma folate, and RBC folate were measured as nutritional biomarkers; serum C-reactive protein (CRP) and serum amyloid A (SAA) were measured as biomarkers of inflammation; and homocysteine and cysteine were measured as integrated biomarkers of one-carbon metabolism. Student's t, chi-square, and Spearman rank correlations, along with multiple linear regressions, were used to explore relations between biomarkers; additionally, we tested stratification by folic acid fortification period and multivitamin use. With the use of univariate analysis, plasma PLP was the only nutritional biomarker that was modestly significantly correlated with serum CRP and SAA (ρ = -0.22 and -0.12, respectively; P < 0.0001). Homocysteine (μmol/L) showed significant inverse correlations with all nutritional biomarkers (ranging from ρ = -0.30 to ρ = -0.46; all P < 0.0001). With the use of multiple linear regression, plasma PLP, RBC folate, homocysteine, and cysteine were identified as independent predictors of CRP; and PLP, vitamin B-12, RBC folate, and homocysteine were identified as predictors of SAA. When stratified by folic acid fortification period, nutrition-homocysteine correlations were generally weaker in the postfortification period, whereas associations between plasma PLP and serum CRP increased. Biomarkers of inflammation are associated with PLP, RBC folate, and homocysteine in women. The connection between the pathways needs to be further investigated and causality established. The trial is registered at clinicaltrials.gov as NCT00000611.

Dietary vitamin B6 intake modulates colonic inflammation in the IL10-/- model of inflammatory bowel disease

Pyridoxal-5-phosphate, the biologically active form of vitamin B6, is a cofactor for over 140 biochemical reactions. Although severe vitamin B6 deficiency is rare, mild inadequacy [plasma pyridoxal 5'-phosphate (PLP) <20 nmol/L] is observed in 19-27% of the US population. Plasma PLP concentrations are inversely related to markers of inflammation such as C-reactive protein. Furthermore, plasma PLP is diminished in those with inflammatory conditions and, in the case of inflammatory bowel disease (IBD), more so in those with active versus quiescent disease. Restricting B6 intake attenuates IBD pathology in mice; however, the effects of supplementation are unclear. We therefore sought to determine the effects of mild inadequacy and moderate supplementation of B6 on the severity of colonic inflammation. Weanling IL-10(-/-) (positive for Helicobacter hepaticus) mice were fed diets containing 0.5 (deficient), 6.0 (replete) or 24 (supplemented) mg/kg pyridoxine HCl for 12 weeks and then assessed for histological and molecular markers of colonic inflammation. Both low and high plasma PLP were associated with a significant suppression of molecular (TNFα, IL-6, IFN-γ, COX-2 and iNOS expression) and histological markers of inflammation in the colon. PLP is required for the breakdown of sphingosine 1-phosphate (S1P), a chemotactic lipid, by S1P lyase. Colonic concentrations of S1P and PLP were significantly and inversely correlated. If confirmed, vitamin B6 supplementation may offer an additional tool for the management of IBD. Although B6 is required in dozens of reactions, its role in the breakdown of S1P may explain the biphasic relationship observed between PLP and inflammation.

Clinical use of cyclooxygenase inhibitors impairs vitamin B-6 metabolism

BACKGROUND

A low circulating vitamin B-6 concentration, which is an independent risk factor for cardiovascular disease, is commonly seen in human inflammation.

OBJECTIVE

We investigated whether cyclooxygenase inhibitors alter vitamin B-6 metabolism.

DESIGN

To investigate whether subjects taking a cyclooxygenase inhibitor had an altered vitamin B-6 profile, we conducted a cross-sectional study that involved 150 rheumatoid arthritis patients, with and without cyclooxygenase inhibitor treatments. C57BL/6J mice and hyperlipidemic Syrian hamsters received drug regimens that reflected clinical nonsteroidal antiinflammatory drug (NSAID) uses in treating human inflammation. The impact of long-term physiologic use of selective and nonselective cyclooxygenase inhibitors on vitamin B-6 metabolism was systematically investigated in these independent in vivo models.

RESULTS

Patients who were taking cyclooxygenase inhibitors had lower circulating pyridoxal-5'-phosphate, especially those taking NSAIDs >6 mo. Long-term celecoxib and naproxen use reduced hepatic pyridoxal-5'-phosphate in mice. Nonselective cyclooxygenase inhibitor naproxen significantly decreased vitamin B-6 vitamers in the kidney.

CONCLUSIONS

To our knowledge, we show novel findings that long-term physiologic doses of cyclooxygenase inhibitor may impede the synthesis of the coenzymatically active form of vitamin B-6. Because the cause of vitamin B-6 depletion in inflammation remains unknown, this study provides a potential mechanism that could account for the poor vitamin B-6 status in human inflammation. Moreover, this study further raises concerns about the long-term clinical use of antiinflammatory NSAIDs in humans. Vitamin B-6 status should be carefully monitored in long-term NSAID users. Future randomized placebo-controlled studies are needed to determine the impacts of antiinflammatory cyclooxygenase inhibitor use on vitamin B-6 metabolism in humans.

Prediagnostic plasma vitamin B6 (pyridoxal 5'-phosphate) and survival in patients with colorectal cancer

PURPOSE

Higher plasma pyridoxal 5'-phosphate (PLP) levels are associated with a decreased incidence of colorectal cancer, but the influence of plasma PLP on survival of patients with colorectal cancer is unknown. We prospectively examined whether prediagnostic plasma PLP levels are associated with mortality among colorectal cancer patients.

METHODS

We included 472 incident cases of colorectal cancer identified in the Nurses' Health Study, the Health Professionals Follow-up Study, and the Physicians' Health Study from 1984 to 2002. The patients provided blood samples two or more years before cancer diagnosis. Stratified Cox proportional hazards models were used to calculate hazard ratios (HR) with 95 % confidence intervals (CI) adjusted for other risk factors for cancer survival.

RESULTS

Higher plasma PLP levels were not associated with a significant reduction in colorectal cancer-specific (169 deaths) or overall mortality (259 deaths). Compared with patients who had less than 45 pmol/ml of plasma PLP (median: 33.6 pmol/ml), those who had 110 pmol/ml or higher levels (median: 158.8 pmol/ml) had multivariable HRs of 0.85 (95 % CI 0.50-1.45, p trend = 0.37) and 0.87 (95 % CI 0.56-1.35, p trend = 0.24) for colorectal cancer-specific and overall mortality. Higher plasma PLP levels, however, seemed to be associated with better survival among patients who had lower circulating 25-hydroxyvitamin D3 levels (<26.5 ng/ml) (p interaction ≤.005).

CONCLUSIONS

Higher prediagnostic plasma PLP levels were not associated with an improvement on colorectal cancer survival overall. Further research is needed to clarify the influence of vitamin B6 on colorectal cancer progression and survival.

Mechanistic perspective on the relationship between pyridoxal 5'-phosphate and inflammation

A variety of inflammatory disease conditions have been found to be associated with low levels of plasma pyridoxal 5'-phosphate (PLP), the active form of vitamin B6 , without any indication of a lower dietary intake of vitamin B6 , excessive catabolism of the vitamin, or congenital defects in its metabolism. The present review was conducted to examine the existing literature in this regard. Current evidence suggests that the inverse association between plasma PLP and inflammation may be the result of mobilization of this coenzyme to the site of inflammation, for use by the PLP-dependent enzymes of the kynurenine pathway of tryptophan degradation, metabolism of the immunomodulatory sphingolipids, ceramide and sphingosine 1-phosphate, and for serine hydroxymethylase for immune cell proliferation.

Vitamin B6: a challenging link between nutrition and inflammation in CVD

The objective of the present review is to highlight the relationship between low vitamin B6 status and CVD through its link with inflammation. While overt vitamin B6 deficiency is uncommon in clinical practice, increasing evidence suggests that marginal vitamin B6 deficiency is rather frequent in a consistent proportion of the population and is related to an increased risk of inflammation-related diseases. Ample evidence substantiates the theory of atherosclerosis as an inflammatory disease, and low plasma vitamin B6 concentrations have been related to increased CVD risk. Several studies have also shown that low vitamin B6 status is associated with rheumatoid arthritis and chronic inflammatory bowel diseases, both of which hold an underlying chronic inflammatory condition. Furthermore, the inverse association observed between inflammation markers and vitamin B6 supports the notion that inflammation may represent the common link between low vitamin B6 status and CVD risk. In addition to the epidemiological evidence, there are a number of cell culture and animal studies that have suggested several possible mechanisms relating impaired vitamin B6 status with chronic inflammation. A mild vitamin B6 deficiency characterises, in most cases, a subclinical at-risk condition in inflammatory-linked diseases which should be addressed by an appropriate individually tailored nutritional preventive or therapeutic strategy.

Plasma pyridoxal-5-phosphate is inversely associated with systemic markers of inflammation in a population of U.S. adults

Low vitamin B-6 status, based on plasma concentrations of pyridoxal-5-phosphate (PLP), has been identified in inflammatory diseases, including cardiovascular disease, rheumatoid arthritis, inflammatory bowel disease, and diabetes. Our objective was to examine the association between plasma PLP and multiple markers of inflammation in a community-based cohort [n = 2229 participants (55% women, mean age 61 ± 9 y)]. We created an overall inflammation score (IS) as the sum of standardized values of 13 individual inflammatory markers. Multivariable-adjusted regression analysis was used to assess the associations between the IS and plasma PLP. Geometric mean plasma PLP concentrations were lower in the highest tertile category of IS relative to the lowest (61 vs. 80 nmol/L; P-trend < 0.0001). Similarly, the prevalence of PLP insufficiency was significantly higher for participants in the highest compared with the lowest tertiles for IS categories. These relationships persisted after accounting for vitamin B-6 intake. Also, there were significant inverse relationships between plasma PLP and 4 IS based on functionally related markers, including acute phase reactants, cytokines, adhesion molecules, and oxidative stress. In addition, secondary analyses revealed that many of the individual inflammatory markers were inversely associated with plasma PLP after adjusting for plasma C-reactive protein concentration. This study, in combination with past findings, further supports our hypothesis that inflammation is associated with a functional deficiency of vitamin B-6. We discuss 2 possible roles for PLP in the inflammatory process, including tryptophan metabolism and serine hydroxymethyltransferase activity.

Association of plasma B-6 vitamers with systemic markers of inflammation before and after pyridoxine treatment in patients with stable angina pectoris

BACKGROUND

A negative association between systemic markers of inflammation and plasma vitamin B-6 has been observed in population-based and patient cohorts; however, vitamin B-6 (pyridoxine) treatment has mostly failed to improve inflammatory indexes.

OBJECTIVE

We aimed to assess the effect of pyridoxine treatment on B-6 vitamer and inflammatory marker relations.

DESIGN

We measured pyridoxal 5'-phosphate (PLP), pyridoxal, 4-pyridoxic acid (PA), C-reactive protein (CRP), neopterin, and the kynurenine-to-tryptophan ratio (KTR) in plasma and the white blood cell count (WBC). A partial Spearman's correlation was used to assess associations of B-6 vitamers with inflammatory markers before and after daily treatment with 40 mg pyridoxine hydrochloride. Generalized additive models and segmented regression analysis were used for nonlinear relations.

RESULTS

A 9-60-fold increase in B-6 vitamer concentrations over baseline values was observed after 28 d of treatment with pyridoxine. PLP was negatively associated with all 4 inflammatory markers at baseline and, predominantly, with CRP and KTR at day 28. The catabolite PA was positively associated with neopterin and KTR before and after treatment. The dose-response relation between CRP and B-6 vitamers at day 28 was nonlinear, with an increased steepness of slope at CRP >7 mg/L. Finally, changes in B-6 vitamer concentrations were correlated with changes in inflammatory marker concentrations over a time span of 4 wk.

CONCLUSIONS

The associations between plasma vitamin B-6 and inflammatory markers were preserved or even increased after pyridoxine treatment. The results suggest that the acute phase and activated cellular immunity are associated with increased cellular uptake and catabolism of vitamin B-6, respectively.

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.

Vitamin B6 suppresses serine protease inhibitor 3 expression in the colon of rats and in TNF-α-stimulated HT-29 cells

SCOPE

Previous reports in the areas of animal studies and, recently epidemiology, have linked anti-tumorigenic and anti-inflammatory effects to dietary vitamin B6. This study investigated the molecular mechanism of these effects of vitamin B6.

METHODS AND RESULTS

DNA microarray analysis was used to obtain information on changes in colon gene expression from vitamin B6 (pyridoxine) repletion in vitamin B6-deficient rats. Pyridoxine supplementation down-regulated the inflammatory molecule, serine protease inhibitor clade A member 3 (SPI-3) mRNA expression in the colon. This study also showed that tumor necrosis factor α (TNF-α) induced SPI-3 mRNA expression in HT-29 human colon cancer cells, and vitamin B6 (pyridoxal hydrochloride) pretreatment of HT-29 cells inhibited TNF -induced mRNA expression of SPI-3. Vitamin B6 inhibited TNF-α-induced NF-κB activation via suppression of IκBα degradation in HT-29 cells. HT-29 cells stably expressing epitope-tagged ubiquitin were generated and vitamin B6 pretreatment was shown to inhibit ubiquitination of the IkB protein in response to TNF-α-i.

CONCLUSION

Vitamin B6 suppressed SPI-3 expression in the colon of rats and in TNF-α-stimulated HT-29 cells. Further, this study showed a possible role of vitamin B6 in the regulation of protein ubiquitination.

Metabolomic analysis identifies inflammatory and noninflammatory metabolic effects of genetic modification in a mouse model of Crohn's disease

Interleukin-10 is an immunosuppressive cytokine involved in the regulation of gastrointestinal mucosal immunity toward intestinal microbiota. Interleukin-10-deficient (IL10(-/-)) mice develop Crohn's disease-like colitis unless raised in germ-free conditions. Previous gas chromatography-mass spectrometry (GC-MS) metabolomic analysis revealed urinary metabolite differences between IL10(-/-) and wildtype C57BL/6 mice. To determine which of these differences were specifically associated with intestinal inflammation arising from IL10-deficiency, urine samples from IL10(-/-) and wildtype mice, housed in either conventional or specific pathogen-free conditions, were subjected to GC-MS metabolomic analysis. Fifteen metabolite differences, including fucose, xanthurenic acid, and 5-aminovaleric acid, were associated with intestinal inflammation. Elevated urinary levels of xanthurenic acid in IL10(-/-) mice were attributed to increased production of kynurenine metabolites that may induce T-cell tolerance toward intestinal microbiota. Liquid chromatography-mass spectrometry analysis confirmed that plasma levels of kynurenine and 3-hydroxykynurenine were elevated in IL10(-/-) mice. Eleven metabolite differences, including glutaric acid, 2-hydroxyglutaric acid, and 2-hydroxyadipic acid, were unaffected by the severity of inflammation. These metabolite differences may be associated with residual genes from the embryonic stem cells of the 129P2 mouse strain that were used to create the IL10(-/-) mouse, or may indicate novel functions of IL10 unrelated to inflammation.

Possible Association between Th1 Immune Polarization and Epithelial Permeability with Toll-Like Receptors 2 Dysfunction in the Pathogenesis of the Recurrent Aphthous Ulceration

Recurrent Aphthous Ulceration (RAU) is a chronic oral inflammatory disease that affects approximately 25% of the general population. The etiology of the disease is unknown; however, factors that favor the onset of RAU have been correlated with a Th1 immune polarization, while factors that reduce RAU episodes have been associated with down regulation of immune reaction or stimulation of the peripheral tolerance. In this context, the integrity of the epithelial barrier is also fundamental for the prevention of the disease and conditions that augment its permeability or produce disruption are considered potential triggers. The key factor responsible for increased susceptibility is unclear, though a deficiency of Toll-like receptor (TLR) activity seems to be a good candidate. TLRs are a group of membrane proteins that recognize conserved molecules derived from bacterial, virus, fungal, or host tissues. Particularly, the TLR2 is involved in both immune regulation and control of epithelial barrier integrity. Thus, based on literature review, we showed evidences that correlate the TLR2 dysfunction and the diverse predisposing factors with the elements considered critical for disease pathogenesis: the Th1 immune reaction and the increased epithelial permeability.

Association of vitamin B-6 status with inflammation, oxidative stress, and chronic inflammatory conditions: the Boston Puerto Rican Health Study

BACKGROUND

Low vitamin B-6 status has been linked to an increased risk of cardiovascular diseases. The cardioprotective effects of vitamin B-6 independent of homocysteine suggest that additional mechanisms may be involved.

OBJECTIVE

Our objective was to examine the cross-sectional association of vitamin B-6 status with markers of inflammation and oxidative stress.

DESIGN

We measured plasma pyridoxal-5'-phosphate (PLP), C-reactive protein (CRP), and an oxidative DNA damage marker, urinary 8-hydroxydeoxyguanosine (8-OHdG), in Puerto Rican adults who were living in Massachusetts (n = 1205, aged 45-75 y).

RESULTS

There was a strong dose-response relation of plasma PLP concentration with plasma CRP. Increasing quartiles of PLP were significantly associated with lower CRP concentrations (geometric means: 4.7, 3.6, 3.1, and 2.5 mg/L; P for trend < 0.0001) and with lower urinary 8-OHdG concentrations (geometric means: 124, 124, 117, and 108 ng/mg creatinine; P for trend: 0.025) after multivariate adjustment. These negative associations persisted after plasma homocysteine was controlled for. Plasma PLP concentrations were significantly correlated with plasma fasting glucose (r = -0.1, P = 0.0006), glycated hemoglobin (r = -0.08, P = 0.006), and homeostasis model assessment of beta cell function (r = 0.082, P = 0.005). Metabolic syndrome, obesity, and diabetes were also significantly associated with low plasma PLP concentrations (P = 0.011, 0.0007, and 0.004, respectively).

CONCLUSIONS

Low vitamin B-6 concentrations are associated with inflammation, higher oxidative stress, and metabolic conditions in older Puerto Rican adults. Our data suggest that vitamin B-6 may influence cardiovascular disease risk through mechanisms other than homocysteine and support the notion that nutritional status may influence the health disparities present in this population.

Vitamin B-6 intake is inversely related to, and the requirement is affected by, inflammation status

Low circulating pyridoxal 5'-phosphate (PLP) concentrations have been linked to inflammatory markers and the occurrence of inflammatory diseases. However, the implications of these findings are unclear. The measurement of PLP and C-reactive protein (CRP) in blood samples collected from participants in the 2003-2004 NHANES afforded us the opportunity to investigate this relationship in the general U.S. population. Dietary and laboratory data were available for 3864 of 5041 interviewed adults, 2686 of whom were eligible (i.e. provided reliable dietary data and were not diabetic, pregnant, lactating, or taking hormones or steroidal antiinflammatory drugs). Vitamin B-6 intake was assessed using 2 24-h diet recalls and supplement use data. After multivariate adjustment for demographics, smoking, BMI, alcohol use, antioxidant vitamin status, intakes of protein and energy, and serum concentrations of creatinine and albumin, high vitamin B-6 intake was associated with protection against serum CRP concentrations >10 mg/L compared with < or =3 mg/L. However, plasma PLP > or =20 nmol/L compared with <20 nmol/L was inversely related to serum CRP independently of vitamin B-6 intake (P < 0.001). Among participants with vitamin B-6 intakes from 2 to 3 mg/d, the multivariate-adjusted prevalence of vitamin B-6 inadequacy was <10% in participants with serum CRP < or =3 mg/L but close to 50% in those with serum CRP > 10 mg/L (P < 0.001). In conclusion, higher vitamin B-6 intakes were linked to protection against inflammation and the vitamin B-6 intake associated with maximum protection against vitamin B-6 inadequacy was increased in the presence compared to absence of inflammation.

Prospective study of plasma vitamin B6 and risk of colorectal cancer in men

Vitamin B(6) may lower risk of colorectal cancer by preventing aberrations in one-carbon metabolism or by anti-inflammatory effects. We prospectively evaluated the association between plasma levels of pyridoxal 5'-phosphate (PLP; the active form of vitamin B(6)) and risk of colorectal cancer in a nested case-control study within the Physicians' Health Study. Among 14,916 men who provided blood specimens in 1982 to 1984, we identified 197 incident colorectal cancer cases through 2000 and individually matched them to 371 controls by age and smoking status. Plasma PLP levels were positively correlated with cold cereal intake and plasma levels of folate and vitamin B(12) (age- and smoking-adjusted partial correction r = 0.28-0.48) and slightly inversely correlated with body mass index (r = -0.11) and plasma levels of homocysteine, C-reactive protein, tumor necrosis factor-alpha receptor 2, and interleukin-6 (r = -0.23 to -0.14). With control for these factors and known risk factors for colorectal cancer, plasma PLP levels were significantly inversely associated with risk of colorectal cancer; compared with men in the lowest quartile, those with PLP in quartiles 2 to 4 had relative risks (95% confidence interval) of 0.92 (0.55-1.56), 0.42 (0.23-0.75), and 0.49 (0.26-0.92; P(trend) = 0.01), respectively. In conclusion, vitamin B(6) may protect against colorectal cancer independent of other one-carbon metabolites and inflammatory biomarkers.

Rheumatoid cachexia: a clinical perspective

Rheumatoid cachexia is under-recognized in clinical practice. The loss of lean body tissue, which characterizes cachexia, is often compensated for by gain in body fat-so called 'cachectic obesity'-so that 85% or more RA patients have a normal BMI. Severe cachexia with loss of weight leads to increased morbidity and premature mortality but loss of muscle bulk with a normal BMI also associates with poor clinical outcomes. Increasing BMI, even into the obese range, is associated with less joint damage and reduced mortality. Measurement of body composition using DXA and other techniques is feasible but the results must be interpreted with care. Newer techniques such as whole-body MRI will help define with more confidence the mass and distribution of fat and muscle and help elucidate the relationships between body composition and outcomes. Cachexia shows little response to diet alone but progressive resistance training and anti-TNF therapies show promise in tackling this potentially disabling extra-articular feature of RA.

Nutrition assessment of patients with inflammatory bowel disease

BACKGROUND

Malnutrition among inflammatory bowel disease (IBD) subjects is well documented in the literature and may arise from factors including inadequate dietary intake, malabsorption, and disease activity. The aims of this present study were to complete a comprehensive nutrition assessment of IBD subjects.

METHODS

One hundred twenty-six consecutive adults with IBD completed anthropometric measures, 4-day food-record assessments, and biochemical markers of nutrition.

RESULTS

A high prevalence of inadequate nutrient consumption was observed: vitamin E (63%), vitamin D (36%), vitamin A (26%), calcium (23%), folate (19%), iron (13%), and vitamin C (11%). Several biochemical deficiencies were also observed. The prevalence of subnormal serum levels was hemoglobin (40%), ferritin (39.2%), vitamin B(6) (29%), carotene (23.4%), vitamin B(12) (18.4%), vitamin D (17.6%), albumin (17.6%), and zinc (15.2%). Dietary intake was not correlated with serum levels in all instances; there was a highly significant correlation between diet and serum values of vitamin B(12), folate, and vitamin B(6) for all IBD subjects, independent of disease activity, and for vitamin D among all IBD subjects in remission.

CONCLUSIONS

Subjects with IBD have a high rate of iron deficiency and anemia, which are most likely not secondary to diet. Supplementing with iron should be warranted only if a true iron deficiency exists. The routine evaluation of serum vitamin B(6) and vitamin D levels is recommended. Routine multivitamin supplementation is warranted in IBD in view of numerous dietary and biochemical deficiencies observed among adult IBD subjects. Even if subjects with IBD seem to be well nourished, they may harbor vitamin/mineral deficiencies.

Association between homocysteine, vitamin B6 concentrations and inflammation

During the last years, a growing body of evidence has been accumulated on the role of hyperhomocysteinemia in the occurrence of coronary artery disease and other arterial occlusive diseases. The mechanism by which high circulating homocysteine concentrations are a risk factor for atherothrombosis is incompletely understood. The present review is aimed to evaluate the role of inflammation in influencing homocysteine (Hcy) and vitamin B

Clin Chem Lab Med 2007;45:1728–36.

Abnormalities of homocysteine and B vitamins in the nephrotic syndrome

INTRODUCTION

The nephrotic syndrome is associated with heightened risk for arterial and venous thrombosis. Multiple derangements of hemostasis and acquired risk factors such as hyperlipidemia and hypertension contribute to this risk. The prevalence in the nephrotic syndrome of high circulating levels of homocysteine and of low levels of the B vitamins that are involved in its metabolism, which may play a role in thrombosis, is not well defined.

MATERIALS AND METHODS

In 84 patients with nephrotic syndrome and 84 sex- and age-matched controls, hemostasis variables and the circulating levels of total homocysteine (tHcy), vitamin B(6), B(12) and folates were measured.

RESULTS

tHcy levels were higher, vitamin B(6) and vitamin B(12) levels were lower in nephrotic patients than in controls. The association of low vitamin B(6) levels with the nephrotic syndrome was independent of any other alteration associated with the disease. Eighty-two percent of patients with the nephrotic syndrome had vitamin B(6) levels falling in the lowest quartile of the normal distribution. Antithrombin deficiency, factor V Leiden, antiphospholipid antibodies, hypertension, dyslipidemia, were more frequent in patients with the nephrotic syndrome than in controls.

CONCLUSIONS

Patients with the nephrotic syndrome have multiple risk factors for thrombosis. We report that they frequently have low circulating levels of vitamin B(6), which associate with a heightened risk for venous and arterial thrombosis.

Supplements and injections for joint disease

Dietary supplements and single joint treatments are gaining increasing popularity, with evidence of efficacy in randomized controlled trials compared with placebo, and minimal side-effects compared with some more traditional therapies. This article clarifies some of the newer approaches and the science behind them.

Diet and rheumatoid arthritis: a review of the literature

INTRODUCTION

Rheumatoid arthritis is a common inflammatory condition. A large number of patients seek alternative or complementary therapies of which diet is an important component. This article reviews the evidence for diet in rheumatoid arthritis along with the associated concept of oral tolerization.

METHODS

References were taken from Medline from 1966 to September 2004. The keywords, rheumatoid arthritis, diet, n-3 fatty acids, vitamins, and oral tolerization, were used.

RESULTS

Randomized controlled trials (RCTs) indicate that dietary supplementation with n-3 fatty acids provides modest symptomatic benefit in groups of patients with rheumatoid arthritis. Epidemiological studies and RCTs show cardiovascular benefits in the broader population and patients with ischemic heart disease. A number of mechanisms through which n-3 fats may reduce inflammation have been identified. In a small number of patients with rheumatoid arthritis, other dietary manipulation such as fasting, vegan, and elimination diets may have some benefit. However, many of these diets are impractical or difficult to sustain long term.

CONCLUSIONS

Dietary manipulation provides a means by which patients can a regain a sense of control over their disease. Dietary n-3 supplementation is practical and can be easily achieved with encapsulated or, less expensively, bottled fish oil.

Pyridoxine supplementation corrects vitamin B6 deficiency but does not improve inflammation in patients with rheumatoid arthritis

Patients with rheumatoid arthritis have subnormal vitamin B6 status, both quantitatively and functionally. Abnormal vitamin B6 status in rheumatoid arthritis has been associated with spontaneous tumor necrosis factor (TNF)-α production and markers of inflammation, including C-reactive protein and erythrocyte sedimentation rate. Impaired vitamin B6 status could be a result of inflammation, and these patients may have higher demand for vitamin B6. The aim of this study was to determine if daily supplementation with 50 mg of pyridoxine for 30 days can correct the static and/or the functional abnormalities of vitamin B6 status seen in patients with rheumatoid arthritis, and further investigate if pyridoxine supplementation has any effects on the pro-inflammatory cytokine TNF-α or IL-6 production of arthritis. This was a double-blinded, placebo-controlled study involving patients with rheumatoid arthritis with plasma pyridoxal 5'-phosphate below the 25th percentile of the Framingham Heart Cohort Study. Vitamin B6 status was assessed via plasma and erythrocyte pyridoxal 5'-phosphate concentrations, the erythrocyte aspartate aminotransferase activity coefficient (αEAST), net homocysteine increase in response to a methionine load test (ΔtHcy), and 24 h urinary xanthurenic acid (XA) excretion in response to a tryptophan load test. Urinary 4-pyridoxic acid (4-PA) was measured to examine the impact of pyridoxine treatment on vitamin B6 excretion in these patients. Pro-inflammatory cytokine (TNF-α and IL-6) production, C-reactive protein levels and the erythrocyte sedimentation rate before and after supplementation were also examined. Pyridoxine supplementation significantly improved plasma and erythrocyte pyridoxal 5'-phosphate concentrations, erythrocyte αEAST, urinary 4-PA, and XA excretion. These improvements were apparent regardless of baseline B6 levels. Pyridoxine supplementation also showed a trend (p < 0.09) towards a reduction in post-methionine load ΔtHcy. Supplementation did not affect pro-inflammatory cytokine production. Although pyridoxine supplementation did not suppress pro-inflammatory cytokine production in patients with rheumatoid arthritis, the suboptimal vitamin B6 status seen in rheumatoid arthritis can be corrected by 50 mg pyridoxine supplementation for 30 days. Data from the present study suggest that patients with rheumatoid arthritis may have higher requirements for vitamin B6 than those in a normal healthy population.

Inflammation causes tissue-specific depletion of vitamin B6

Previously we observed strong and consistent associations between vitamin B₆ status and several indicators of inflammation in patients with rheumatoid arthritis. Clinical indicators, including the disability score, the length of morning stiffness, and the degree of pain, and biochemical markers, including the erythrocyte sedimentation rate and C-reactive protein levels, were found to be inversely correlated with circulating vitamin B₆ levels. Such strong associations imply that impaired vitamin B₆ status in these patients results from inflammation. In the present study we examined whether inflammation directly alters vitamin B₆ tissue contents and its excretion in vivo. A cross-sectional case-controlled human clinical trial was performed in parallel with experiments in an animal model of inflammation. Plasma and erythrocyte and pyridoxal 5'-phosphate concentrations, urinary 4-pyridoxic acid excretion, and the activity coefficient of erythrocyte aspartate aminotransferase were compared between patients and healthy subjects. Adjuvant arthritis was induced in rats for investigating hepatic and muscle contents as well as the urinary excretion of vitamin B₆ during acute and chronic inflammation. Patients with rheumatoid arthritis had low plasma pyridoxal 5'-phosphate compared with healthy control subjects, but normal erythrocyte pyridoxal 5'-phosphate and urinary 4-pyridoxic acid excretion. Adjuvant arthritis in rats did not affect 4-pyridoxic acid excretion or muscle storage of pyridoxal 5'-phosphate, but it resulted in significantly lower pyridoxal 5'-phosphate levels in circulation and in liver during inflammation. Inflammation induced a tissue-specific depletion of vitamin B₆. The low plasma pyridoxal 5'-phosphate levels seen in inflammation are unlikely to be due to insufficient intake or excessive vitamin B₆ excretion. Possible causes of decreased levels of vitamin B₆ are discussed.

The use of methotrexate in rheumatoid arthritis

OBJECTIVE

To address the long-term efficacy and toxicity issues related to methotrexate (MTX) and compare it with other disease-modifying antirheumatic drugs (DMARDs).

METHODS

Review of the international literature on the clinical use of MTX in rheumatoid arthritis (RA) disease.

RESULTS

MTX has emerged as a relatively safe and effective treatment for RA that compares favorably with other therapies, particularly because of its considerably longer median drug survival. The toxicity profile of MTX is well established and includes serious and sometimes fatal liver disease, pneumonitis, and cytopenias. Hence, regular and careful monitoring of patients taking MTX is essential, particularly when MTX is combined with other DMARDs. Folate supplementation can reduce some of the most common side effects of MTX, but it has not yet been established whether this translates into a reduced risk of serious disease. Another potential approach to reducing the toxicity of MTX is therapeutic drug monitoring and dose individualization. However, correlations between pharmacokinetics and clinical response have been addressed in only a few studies and with conflicting results.

CONCLUSIONS

MTX is an effective DMARD with a relatively safe profile compared with other therapies. Folate supplementation can significantly reduce the risk of MTX toxicity. Finally, it is essential that patients be monitored carefully to reduce the potential serious toxicities of MTX.

Low plasma vitamin B-6 concentrations and modulation of coronary artery disease risk

BACKGROUND

Low concentrations of pyridoxal-5'-phosphate (PLP), the active metabolite of vitamin B-6, are associated with high C-reactive protein (CRP) concentrations. Both low PLP and elevated inflammatory markers, such as high-sensitivity CRP (hs-CRP) and fibrinogen, are related to higher risk of coronary artery disease (CAD).

OBJECTIVES

The objectives were to evaluate the relation between PLP and acute-phase reactants in affecting CAD risk and to estimate the risk of CAD related to low plasma PLP, either alone or in combination with high concentrations of acute-phase reactants and other classic risk factors for CAD.

DESIGN

A case-control study was conducted with 742 participants: 475 with severe multivessel CAD and 267 free from coronary atherosclerosis (CAD-free). We measured plasma PLP, fibrinogen, hs-CRP, and serum lipid concentrations and all major biochemical CAD risk factors, including total homocysteine.

RESULTS

A significant, inverse, graded relation was observed between PLP and both hs-CRP and fibrinogen (P < 0.001). The prevalence of PLP concentrations in the lower half of the population (<50th percentile: 36.3 nmol/L) was significantly higher among CAD patients than among CAD-free subjects (P < 0.001). The odds ratio for CAD risk related to low PLP concentrations after adjustments for the major classic CAD risk factors, including hs-CRP and fibrinogen, was 1.89 (95% CI: 1.18, 3.03; P = 0.008). The CAD risk as a result of low PLP was additive when considered in combination with elevated hs-CRP concentrations or with an increased ratio of LDL to HDL.

CONCLUSION

Low plasma PLP concentrations are inversely related to major markers of inflammation and independently associated with increased CAD risk.

Inflammation, Homocysteine, and Vitamin B6 Status After Ischemic Stroke

BACKGROUND AND PURPOSE

Epidemiological studies have described an association between low vitamin B6 (measured as pyridoxal 5'-phosphate [PLP]) and ischemic stroke, independent of homocysteine (tHcy). We investigated B6 status, tHcy, and inflammation (measured by C-reactive protein [CRP]) in patients with stroke and controls.

METHODS

Consecutive cases with new ischemic stroke were compared with matched controls. Fasting tHcy, PLP, and CRP were measured.

RESULTS

The adjusted odds ratio of low PLP in the highest compared with the lowest CRP quartile was 16.6 (2, 139.9, P=0.01). Age, CRP, supplemental vitamin use, and albumin were independent predictors of PLP (P<0.05 for all). No relationship was observed between CRP and tHcy.

CONCLUSIONS

The relationship between inflammation and low B6 status may partially explain the findings of previous epidemiological studies.