Biological Effects of Intravenous Vitamin C on Neutrophil Extracellular Traps and the Endothelial Glycocalyx in Patients with Sepsis-Induced ARDS.

(1) Background: The disease-modifying mechanisms of high-dose intravenous vitamin C (HDIVC) in sepsis induced acute respiratory distress syndrome (ARDS) is unclear. (2) Methods: We performed a post hoc study of plasma biomarkers from subjects enrolled in the randomized placebo-controlled trial CITRIS-ALI. We explored the effects of HDIVC on cell-free DNA (cfDNA) and syndecan-1, surrogates for neutrophil extracellular trap (NET) formation and degradation of the endothelial glycocalyx, respectively. (3) Results: In 167 study subjects, baseline cfDNA levels in HDIVC (84 subjects) and placebo (83 subjects) were 2.18 ng/µL (SD 4.20 ng/µL) and 2.65 ng/µL (SD 3.87 ng/µL), respectively, p = 0.45. At 48-h, the cfDNA reduction was 1.02 ng/µL greater in HDIVC than placebo, p = 0.05. Mean baseline syndecan-1 levels in HDIVC and placebo were 9.49 ng/mL (SD 5.57 ng/mL) and 10.83 ng/mL (SD 5.95 ng/mL), respectively, p = 0.14. At 48 h, placebo subjects exhibited a 1.53 ng/mL (95% CI, 0.96 to 2.11) increase in syndecan-1 vs. 0.75 ng/mL (95% CI, 0.21 to 1.29, p = 0.05), in HDIVC subjects. (4) Conclusions: HDIVC infusion attenuated cell-free DNA and syndecan-1, biomarkers associated with sepsis-induced ARDS. Improvement of these biomarkers suggests amelioration of NETosis and shedding of the vascular endothelial glycocalyx, respectively.

The Emerging Role of Vitamin C as a Treatment for Sepsis.

Sepsis, a life-threatening organ dysfunction due to a dysregulated host response to infection, is a leading cause of morbidity and mortality worldwide. Decades of research have failed to identify any specific therapeutic targets outside of antibiotics, infectious source elimination, and supportive care. More recently, vitamin C has emerged as a potential therapeutic agent to treat sepsis. Vitamin C has been shown to be deficient in septic patients and the administration of high dose intravenous as opposed to oral vitamin C leads to markedly improved and elevated serum levels. Its physiologic role in sepsis includes attenuating oxidative stress and inflammation, improving vasopressor synthesis, enhancing immune cell function, improving endovascular function, and epigenetic immunologic modifications. Multiple clinical trials have demonstrated the safety of vitamin C and two recent studies have shown promising data on mortality improvement. Currently, larger randomized controlled studies are underway to validate these findings. With further study, vitamin C may become standard of care for the treatment of sepsis, but given its safety profile, current treatment can be justified with compassionate use.

Interventional vitamin C: A strategy for attenuation of coagulopathy and inflammation in a swine multiple injuries model.

BACKGROUND: Coagulopathy and inflammation induced by hemorrhagic shock and traumatic injury are associated with increased mortality and morbidity. Vitamin C (VitC) is an antioxidant with potential protective effects on the proinflammatory and procoagulant pathways. We hypothesized that high-dose VitC administered as a supplement to fluid resuscitation would attenuate inflammation, coagulation dysfunction, and end-organ tissue damage in a swine model of multiple injuries and hemorrhage. METHODS: Male Sinclair swine (n = 24; mean body weight, 27 kg) were anesthetized, intubated, mechanically ventilated, and instrumented for physiologic monitoring. Following stabilization, swine were subjected to shock/traumatic injury (hypothermia, liver ischemia and reperfusion, comminuted femur fracture, hemorrhagic hypotension), resuscitated with 500 mL of hydroxyethyl starch, and randomized to receive either intravenous normal saline (NS), low-dose VitC (50 mg/kg; LO), or high-dose VitC (200 mg/kg; HI). Hemodynamics, blood chemistry, hematology, and coagulation function (ROTEM) were monitored to 4 hours postresuscitation. Histological and molecular analyses were obtained for liver, kidney, and lung. RESULTS: Compared with VitC animals, NS swine showed significant histological end-organ damage, elevated acute lung injury scores, and increased mRNA expression of tissue proinflammatory mediators (IL-1ß, IL-8, TNFα), plasminogen activation inhibitor-1 and tissue factor. There were no statistically significant differences between treatment groups on mean arterial pressure or univariate measures of coagulation function; however, NS showed impaired multivariate clotting function at 4 hours. CONCLUSION: Although correction of coagulation dysfunction was modest, intravenous high-dose VitC may mitigate the proinflammatory/procoagulant response that contributes to multiple organ failure following acute severe multiple injuries. LEVEL OF EVIDENCE: Prospective randomized controlled blinded trial study, Preclinical (animal-based).

Attenuation of Red Blood Cell Storage Lesions with Vitamin C.

Stored red blood cells (RBCs) undergo oxidative stress that induces deleterious metabolic, structural, biochemical, and molecular changes collectively referred to as "storage lesions". We hypothesized that vitamin C (VitC, reduced or oxidized) would reduce red cell storage lesions, thus prolonging their storage duration. Whole-blood-derived, leuko-reduced, SAGM (saline-adenine-glucose-mannitol)-preserved RBC concentrates were equally divided into four pediatric storage bags and the following additions made: (1) saline (saline); (2) 0.3 mmol/L reduced VitC (Lo VitC); (3) 3 mmol/L reduced VitC (Hi VitC); or (4) 0.3 mmol/L oxidized VitC (dehydroascorbic acid, DHA) as final concentrations. Biochemical and rheological parameters were serially assessed at baseline (prior to supplementation) and Days 7, 21, 42, and 56 for RBC VitC concentration, pH, osmotic fragility by mechanical fragility index, and percent hemolysis, LDH release, glutathione depletion, RBC membrane integrity by scanning electron microscopy, and Western blot for ß-spectrin. VitC exposure (reduced and oxidized) significantly increased RBC antioxidant status with varying dynamics and produced trends in reduction in osmotic fragility and increases in membrane integrity. CONCLUSION: VitC partially protects RBC from oxidative changes during storage. Combining VitC with other antioxidants has the potential to improve long-term storage of RBC.

Vitamin C promotes wound healing through novel pleiotropic mechanisms.

Vitamin C (VitC) or ascorbic acid (AscA), a cofactor for collagen synthesis and a primary antioxidant, is rapidly consumed post-wounding. Parenteral VitC administration suppresses pro-inflammatory responses while promoting anti-inflammatory and pro-resolution effects in human/murine sepsis. We hypothesised that VitC could promote wound healing by altering the inflammatory, proliferative and remodelling phases of wound healing. Mice unable to synthesise VitC (Gulo(-/-) ) were used in this study. VitC was provided in the water (sufficient), withheld from another group (deficient) and supplemented by daily intra-peritoneal infusion (200 mg/kg, deficient + AscA) in a third group. Full thickness excisional wounds (6 mm) were created and tissue collected on days 7 and 14 for histology, quantitative polymerase chain reaction (qPCR) and Western blotting. Human neonatal dermal fibroblasts (HnDFs) were used to assess effects of In conclusion, VitC favorably on proliferation. Histological analysis showed improved wound matrix deposition and organisation in sufficient and deficient +AscA mice. Wounds from VitC sufficient and deficient + AscA mice had reduced expression of pro-inflammatory mediators and higher expression of wound healing mediators. Supplementation of HnDF with AscA induced the expression of self-renewal genes and promoted fibroblast proliferation. VitC favourably impacts the spatiotemporal expression of transcripts associated with early resolution of inflammation and tissue remodelling.

Ascorbate-dependent vasopressor synthesis: a rationale for vitamin C administration in severe sepsis and septic shock?

Severe systemic inflammatory response to infection results in severe sepsis and septic shock, which are the leading causes of death in critically ill patients. Septic shock is characterised by refractory hypotension and is typically managed by fluid resuscitation and administration of catecholamine vasopressors such as norepinephrine. Vasopressin can also be administered to raise mean arterial pressure or decrease the norepinephrine dose. Endogenous norepinephrine and vasopressin are synthesised by the copper-containing enzymes dopamine ß-hydroxylase and peptidylglycine α-amidating monooxygenase, respectively. Both of these enzymes require ascorbate as a cofactor for optimal activity. Patients with severe sepsis present with hypovitaminosis C, and pre-clinical and clinical studies have indicated that administration of high-dose ascorbate decreases the levels of pro-inflammatory biomarkers, attenuates organ dysfunction and improves haemodynamic parameters. It is conceivable that administration of ascorbate to septic patients with hypovitaminosis C could improve endogenous vasopressor synthesis and thus ameliorate the requirement for exogenously administered vasopressors. Ascorbate-dependent vasopressor synthesis represents a currently underexplored biochemical mechanism by which ascorbate could act as an adjuvant therapy for severe sepsis and septic shock.

Resolution of sterile inflammation: role for vitamin C.

INTRODUCTION: Macrophage reprogramming is vital for resolution of acute inflammation. Parenteral vitamin C (VitC) attenuates proinflammatory states in murine and human sepsis. However information about the mechanism by which VitC regulates resolution of inflammation is limited. METHODS: To examine whether physiological levels of VitC modulate resolution of inflammation, we used transgenic mice lacking L-gulono-γ-lactone oxidase. VitC sufficient/deficient mice were subjected to a thioglycollate-elicited peritonitis model of sterile inflammation. Some VitC deficient mice received daily parenteral VitC (200 mg/kg) for 3 or 5 days following thioglycollate infusion. Peritoneal macrophages harvested on day 3 or day 5 were examined for intracellular VitC levels, pro- and anti-inflammatory protein and lipid mediators, mitochondrial function, and response to lipopolysaccharide (LPS). The THP-1 cell line was used to determine the modulatory activities of VitC in activated human macrophages. RESULTS: VitC deficiency significantly delayed resolution of inflammation and generated an exaggerated proinflammatory response to in vitro LPS stimulation. VitC sufficiency and in vivo VitC supplementation restored macrophage phenotype and function in VitC deficient mice. VitC loading of THP-1 macrophages attenuated LPS-induced proinflammatory responses. CONCLUSION: VitC sufficiency favorably modulates macrophage function. In vivo or in vitro VitC supplementation restores macrophage phenotype and function leading to timely resolution of inflammation.

Mechanisms of attenuation of abdominal sepsis induced acute lung injury by ascorbic acid.

Bacterial infections of the lungs and abdomen are among the most common causes of sepsis. Abdominal peritonitis often results in acute lung injury (ALI). Recent reports demonstrate a potential benefit of parenteral vitamin C [ascorbic acid (AscA)] in the pathogenesis of sepsis. Therefore we examined the mechanisms of vitamin C supplementation in the setting of abdominal peritonitis-mediated ALI. We hypothesized that vitamin C supplementation would protect lungs by restoring alveolar epithelial barrier integrity and preventing sepsis-associated coagulopathy. Male C57BL/6 mice were intraperitoneally injected with a fecal stem solution to induce abdominal peritonitis (FIP) 30 min prior to receiving either AscA (200 mg/kg) or dehydroascorbic acid (200 mg/kg). Variables examined included survival, extent of ALI, pulmonary inflammatory markers (myeloperoxidase, chemokines), bronchoalveolar epithelial permeability, alveolar fluid clearance, epithelial ion channel, and pump expression (aquaporin 5, cystic fibrosis transmembrane conductance regulator, epithelial sodium channel, and Na(+)-K(+)-ATPase), tight junction protein expression (claudins, occludins, zona occludens), cytoskeletal rearrangements (F-actin polymerization), and coagulation parameters (thromboelastography, pro- and anticoagulants, fibrinolysis mediators) of septic blood. FIP-mediated ALI was characterized by compromised lung epithelial permeability, reduced alveolar fluid clearance, pulmonary inflammation and neutrophil sequestration, coagulation abnormalities, and increased mortality. Parenteral vitamin C infusion protected mice from the deleterious consequences of sepsis by multiple mechanisms, including attenuation of the proinflammatory response, enhancement of epithelial barrier function, increasing alveolar fluid clearance, and prevention of sepsis-associated coagulation abnormalities. Parenteral vitamin C may potentially have a role in the management of sepsis and ALI associated with sepsis.