Open Access

Vitamin B6 deficiency during pregnancy translates into a severe vitamin B6 deficiency (plasma levels decreased by 97%) in new-born rats. Further, hallmarks are increased (+89%) concentrations of homocysteine, gross changes in gene methylation and expression, and metabolic alterations including lipid metabolism. This study focuses on determining the effects of vitamin B6-deficiency on cardiolipin composition and oxidative phosphorylation in liver. For this purpose, hepatic cardiolipin composition was analyzed by means of LC/MS/MS, and mitochondrial oxygen consumption was determined by using a Clark-type electrode in a rat model of vitamin B6 deficiency. Liver mitochondria from new-born rats with pre-term vitamin B6 deficiency responded with substantial alterations in cardiolipin composition that include the following changes in the amounts of cardiolipin incorporated fatty acids: increase in C16, decrease in C18, decrease in saturated fatty acid, as well as increase in amount of oxidized cardiolipin species. These changes were accompanied by significantly decreased capacity of oxidative phosphorylation. In conclusion, vitamin B6 deficiency in new born rats induces massive alterations of cardiolipin composition and function of liver mitochondria. These findings support the importance of sufficient periconceptional supply of vitamin B6 to prevent vitamin B6 deficiency. Impact statement Vitamin B6 (VitB6) is an active co-enzyme for more than 150 enzymes and is required for a great diversity of biosynthesis and metabolic reactions. There is an increased need for VitB6 during pregnancy and sufficient supply of VitB6 is crucial for the prevention of cleft palate and neural tube defects. We show that liver mitochondria from new-born rats with pre-term VitB6 deficiency respond with substantial alterations in cardiolipin (CL) composition and in the amount of oxidized CL species. These changes are associated with a decrease in the efficiency of oxidative phosphorylation. The results of this study support the significance of sufficient supply of VitB6 during pregnancy (and periconceptional) for diminishing the number of early abortions and minimizing malformation. The established link between VitB6 deficiency, CL composition, and mitochondrial respiration/energy production provides mechanistic insight as to how the VitB6 deficiency translates into the known pathophysiological and clinically relevant conditions.

Background: Animal model studies revealed that the application of 1-methyltryptophan (1-MT), a tryptophan (TRP) analog, surprisingly increased plasma levels of the TRP metabolite, kynurenic acid (KYNA). Under inflammatory conditions, KYNA has been shown to mediate various immunomodulatory effects. Therefore, the present study aims to confirm and clarify the effects of 1-MT on TRP metabolism in mice as well as in humans. Methods: Splenocytes from Balb/C or indoleamine 2,3-dioxygenase knockout (IDO1−/−) mice or whole human blood were stimulated with 1-MT for 6, 24, or 36 h. C57BL/6 mice received 1-MT in drinking water for 5 days. Cell-free supernatants and plasma were analyzed for TRP and its metabolites by tandem mass spectrometry (MS/MS). Results: 1-MT treatment induced an increase in TRP and its metabolite, KYNA in Balb/C, IDO−/− mice, and in human blood. Concurrently, the intermediate metabolite kynurenine (KYN), as well as the KYN/TRP ratio, were reduced after 1-MT treatment. The effects of 1-MT on TRP metabolites were similar after the in vivo application of 1-MT to C57BL/6 mice. Conclusions: The data indicate that 1-MT induced an increase of KYNA ex vivo and in vivo confirming previously described results. Furthermore, the results of IDO−/− mice indicate that this effect seems not to be mediated by IDO1. Due to the proven immunomodulatory properties of KYNA, a shift toward this branch of the kynurenine pathway (KP) may be one potential mode of action by 1-MT and should be considered for further applications.

Protection against Staphylococcus aureus is determined by the polarization of the anti-bacterial immune effector mechanisms. Virulence factors of S. aureus can modulate these and induce differently polarized immune responses in a single individual. We proposed that this may be due to intrinsic properties of the bacterial proteins. To test this idea, we selected two virulence factors, the serine protease-like protein B (SplB) and the glycerophosphoryl diester phosphodiesterase (GlpQ). In humans naturally exposed to S. aureus, SplB induces a type 2-biased adaptive immune response, whereas GlpQ elicits type 1/type 3 immunity. We injected the recombinant bacterial antigens into the peritoneum of S. aureus-naïve C57BL/6N mice and analyzed the immune response. This was skewed by SplB toward a Th2 profile including specific IgE, whereas GlpQ was weakly immunogenic. To elucidate the influence of adjuvants on the proteins’ polarization potential, we studied Montanide ISA 71 VG and Imject™Alum, which promote a Th1 and Th2 response, respectively. Alum strongly increased antibody production to the Th2-polarizing protein SplB, but did not affect the response to GlpQ. Montanide enhanced the antibody production to both S. aureus virulence factors. Montanide also augmented the inflammation in general, whereas Alum had little effect on the cellular immune response. The adjuvants did not override the polarization potential of the S. aureus proteins on the adaptive immune response.

The local anesthetic lidocaine, which has been used extensively during liposuction, has been reported to have cytotoxic effects and therefore would be unsuitable for use in autologous lipotransfer. We evaluated the effect of lidocaine on the distribution, number, and viability of adipose-derived stem cells (ASCs), preadipocytes, mature adipocytes, and leukocytes in the fatty and fluid portion of the lipoaspirate using antibody staining and flow cytometry analyses. Adipose tissue was harvested from 11 female patients who underwent liposuction. Abdominal subcutaneous fat tissue was infiltrated with tumescent local anesthesia, containing lidocaine on the left and lacking lidocaine on the right side of the abdomen, and harvested subsequently. Lidocaine had no influence on the relative distribution, cell number, or viability of ASCs, preadipocytes, mature adipocytes, or leukocytes in the stromal-vascular fraction. Assessing the fatty and fluid portions of the lipoaspirate, the fatty portions contained significantly more ASCs (p < 0.05), stem cells expressing the preadipocyte marker Pref-1 (p < 0.01 w/lidocaine, p < 0.05 w/o lidocaine), and mature adipocytes (p < 0.05 w/lidocaine, p < 0.01 w/o lidocaine) than the fluid portions. Only the fatty portion should be used for transplantation. This study found no evidence that would contraindicate the use of lidocaine in lipotransfer. Limitations of the study include the small sample size and the inclusion of only female patients.