L-carnosine alters some hemorheologic and lipid peroxidation parameters in nephrectomized rats

Carnosine attenuates renal ischemia-reperfusion injury by inhibiting GPX4-mediated ferroptosis

Increasing evidence and our preliminary work have revealed the significant role of ferroptosis in acute kidney injury (AKI) induced by ischemia/reperfusion (IR). Carnosine (Car), a dipeptide consisting of β-alanine and L-histidine, has been shown to ameliorate HG-induced tubular epithelial cells inflammation. Whether Car exerts protective effects on AKI, and its molecular mechanism have not been clarified. Our in vivo and in vitro IR-AKI mouse models demonstrated that Car alleviates kidney injury, inflammation and ferroptosis. In hypoxia/reoxygenation (HR) induced human renal tubular epithelial cells (HK2), Car treatment reduced lipid peroxidation and iron accumulation, suppressed oxidative stress, and inhibited ferroptosis. Through cellular thermal shift assay (CETSA) and molecular docking, we identified GPX4 as a potential target that binds with Car. Further study showed that overexpressed GPX4 had a comparable protective effect on HK2 cells under HR conditions, similar to Car. Additionally, our findings demonstrated that Car exhibited similar anti-ferroptosis effects in both folic acid (FA)-induced AKI mouse models and Erastin induced HK2 cells. In conclusion, our results highlight that Car alleviate renal IR injury by inhibiting GPX4-mediated ferroptosis. Car shows promise as a potential therapeutic drug for IR-AKI and other diseases associated with ferroptosis.

Pinocembrin Decreases Atrial Fibrillation Susceptibility in a Rodent Model of Depression

Background

Depression is often comorbid with cardiovascular diseases and contributes to the development and maintenance of atrial fibrillation (AF). Ample research demonstrated that pinocembrin had protective effects on the neuropsychiatric and cardiovascular systems via its pharmacological properties. However, whether pinocembrin protects from AF in depression models is not known. The present research investigated antiarrhythmic effects of pinocembrin and the underlying mechanisms in depressed rats.

Methods

One hundred and ten male Sprague Dawley rats were randomly divided into six groups: the CTL group (the normal rats administered saline), the CTP group (the normal rats administered pinocembrin), the MDD group (the depressed rats administered saline), the MDP group (the depressed rats administered pinocembrin), the MDA group (the depressed rats administered apocynin), and the MPA group (the depressed rats administered both pinocembrin and apocynin). Chronic unpredictable mild stress (CUMS) was performed for 28 days to establish the depression model. Pinocembrin was administered via gavage from Day 8 to Day 28, and apocynin was administered via intraperitoneal injection from Day 1 to Day 28. The effects were evaluated using behavioral measurements, in vitro electrophysiological studies, whole-cell patch-clamp recordings, biochemical detection, Western blot, and histological studies.

Results

Pinocembrin treatment significantly attenuated the abnormality of heart rate variability (HRV), the prolongation of action potential duration (APD), the shortening of the effective refractory period (ERP), the reduction of transient outward potassium current (I_to), and the increase in L-type calcium current (I_Ca–L), which increase susceptibility to AF in a rat model of depression. Compared to the depressed rats, pinocembrin also increased the content of Kv4.2, Kv4.3, and atrial gap junction channel Cx40 and decreased the expression level of Cav1.2, which ameliorated oxidative stress and inhibited the ROS/p-p38MAPK pro-apoptotic pathway and the ROS/TGF-β1 pro-fibrotic pathway.

Conclusion

Pinocembrin is a therapeutic strategy with great promise for the treatment of AF in depressed patients by reducing oxidative stress.

Fate determination role of erythropoietin and romiplostim in the lineage commitment of hematopoietic progenitors

Erythropoietin (EPO) and thrombopoietin (TPO) have long been known to promote erythropoiesis and megakaryopoiesis, respectively. However, the fate changing role of EPO and TPO on megakaryocyte-erythroid progenitors (MEPs) to develop along the erythroid versus megakaryocyte (MK) lineage remains unclear. We have previously shown that EPO may have fate changing role because EPO treatment could induce progenitor cells depletion and resulted in EPO resistance. Therefore, we hypothesize that a combination of romiplostim, a TPO receptor agonist that could stimulate the expansion of progenitors, with EPO can treat EPO resistance. Using rats with anemia due to chronic kidney disease, we demonstrated that romiplostim synergized with EPO to promote red blood cells production while EPO inhibited platelet production in a dose-dependent manner to reduce the risk of thrombosis. Corroborating findings from in vivo, in vitro experiments demonstrated that romiplostim expanded hematopoietic stem cells and stimulated megakaryopoiesis, while EPO drove the progenitors toward an erythroid fate. We further developed a novel pharmacokinetic-pharmacodynamic model to quantify the effects of EPO and romiplostim on megakaryopoiesis and erythropoiesis simultaneously. The modeling results demonstrated that EPO increased the differentiation rate of MEPs into burst-forming unit-erythroid up to 22-fold, indicating that the slight increase of MEPs induced by romiplostim could be further amplified and recruited by EPO to promote erythropoiesis. The data herein support that romiplostim in combination with EPO can treat EPO resistance. Significance Statement This study clarified that erythropoietin (EPO) drives the fate of megakaryocyte-erythroid progenitors (MEP) toward the erythroid lineage, thus reducing their megakaryocyte (MK) lineage commitment, whereas romiplostim, a thrombopoietin (TPO) receptor agonist (RA), stimulates megakaryopoiesis through the MK-committed progenitor and MEP bifurcation pathways simultaneously. These findings support an innovative combination of romiplostim and EPO to treat EPO-resistant anemia, because the combination therapy further promotes erythropoiesis compared to EPO monotherapy and inhibit platelet production compared to romiplostim monotherapy.

Clinical Efficacy and Safety of Non-Cross-Linked Hyaluronic Acid Combined with L-carnosine for Horizontal Neck Wrinkles Treatment

Background Horizontal neck wrinkle formation is gaining more attention among cosmetic practitioners and clients. To date, hyaluronic acid products are one of the most common treatment options for this aesthetic concern. However, different therapeutic strategies should be given to solve the problem due to multiple etiological reasons. Given that oxidative damage plays a critical role in neck wrinkle formation, anti-oxidative compounds are now considered by physicians when making a treatment plan. Aims To evaluate the efficacy and safety of a non-cross-linked hyaluronic acid filler in combination with L-carnosine in treating horizontal neck wrinkles. Methods Thirteen patients with a Wrinkle Assessment Scale (WAS) of 2–5 for horizontal neck wrinkles were treated with L-carnosine-containing non-cross-linked hyaluronic acid. Participants were followed-up for 3 months after treatment. The post-treated WAS scores evaluated by physicians were collected when patient satisfaction was surveyed. Any post-treatment adverse events were recorded. Results With a single injection of the above filler, the physician-evaluated WAS scores improved by at least one score at one month and the improvement kept consistent as far as three months after injection. According to the last follow-up visit, 11/13 patients were satisfied with the treatment effect of their neck wrinkle. Moreover, adverse events were rare after filler injection, except for local complications that were considered common reactions to the filler injection procedure. Conclusion The non-cross-linked hyaluronic acid filler containing L-carnosine is safe and effective for treating horizontal neck wrinkles.

Level of Evidence IV This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Effect of Oral carnosine supplementation on urinary TGF-β in diabetic nephropathy: a randomized controlled trial

Background

Activation of the transforming growth factor beta (TGF-β) pathway is a significant contributor to the pathogenesis of diabetic nephropathy. Carnosine is a dipeptide that can inhibit TGF-β synthesis. We tested the hypothesis that carnosine supplement added to standard therapy will result in reduced urinary TGF-β levels among patients with diabetic nephropathy.

Methods

We randomly assigned 40 patients with diabetic nephropathy and albuminuria 30–299 mg/day to treatment with carnosine (2 g/day) or placebo for 12 weeks. Urinary TGF-β level was determined using ELISA, urine albumin was ascertained by immunonephelometric assay, and renal function and metabolic profiles were determined at baseline and during 12 weeks of active treatment. Primary outcome was decrease in urinary levels of TGF-β.

Results

The 2 groups were comparable for baseline characteristics, blood pressure, urine albumin, urine TGF-β and renal function measurements. Urinary TGF-β significantly decreased with carnosine supplement (− 17.8% of the baseline values), whereas it tended to increase with placebo (+ 16.9% of the baseline values) (between-group difference P < 0.05). However, blood urea nitrogen, serum creatinine, glomerular filtration rate and other biochemical parameters remained unchanged during the study period including urinary albuminuria. Both groups were well tolerated with no serious side-effects.

Conclusions

These data indicated an additional renoprotective effect of oral supplementation with carnosine to decrease urinary TGF-β level that serves as a marker of renal injury in diabetic nephropathy.

Trial registration

Thai Clinical Trials, TCTR20200724002. Retrospectively Registered 24 July 2020.

Carbonyl Stress in Red Blood Cells and Hemoglobin

The paper overviews the peculiarities of carbonyl stress in nucleus-free mammal red blood cells (RBCs). Some functional features of RBCs make them exceptionally susceptible to reactive carbonyl compounds (RCC) from both blood plasma and the intracellular environment. In the first case, these compounds arise from the increased concentrations of glucose or ketone bodies in blood plasma, and in the second-from a misbalance in the glycolysis regulation. RBCs are normally exposed to RCC-methylglyoxal (MG), triglycerides-in blood plasma of diabetes patients. MG modifies lipoproteins and membrane proteins of RBCs and endothelial cells both on its own and with reactive oxygen species (ROS). Together, these phenomena may lead to arterial hypertension, atherosclerosis, hemolytic anemia, vascular occlusion, local ischemia, and hypercoagulation phenotype formation. ROS, reactive nitrogen species (RNS), and RCC might also damage hemoglobin (Hb), the most common protein in the RBC cytoplasm. It was Hb with which non-enzymatic glycation was first shown in living systems under physiological conditions. Glycated HbA1c is used as a very reliable and useful diagnostic marker. Studying the impacts of MG, ROS, and RNS on the physiological state of RBCs and Hb is of undisputed importance for basic and applied science.

Carnosine and Kidney Diseases: What We Currently Know?

Carnosine (beta-alanyl-L-histidine) is an endogenously synthesised dipeptide which is present in different human tissues e.g. in the kidney. Carnosine is degraded by enzyme serum carnosinase, encoding by CNDP1 gene. Carnosine is engaged in different metabolic pathways in the kidney. It reduces the level of proinflammatory and profibrotic cytokines, inhibits advanced glycation end products' formation, moreover, it also decreases the mesangial cell proliferation. Carnosine may also serve as a scavenger of peroxyl and hydroxyl radicals and a natural angiotensin-converting enzyme inhibitor. This review summarizes the results of experimental and human studies concerning the role of carnosine in kidney diseases, particularly in chronic kidney disease, ischemia/reperfusion-induced acute renal failure, diabetic nephropathy and also drug-induced nephrotoxicity. The interplay between serum carnosine concentration and serum carnosinase activity and polymorphism in the CNDP1 gene is discussed. Carnosine has renoprotective properties. It has a promising potential for the treatment and prevention of different kidney diseases, particularly chronic kidney disease which is a global public health issue. Further studies of the role of carnosine in the kidney may offer innovative and effective strategies for the management of kidney diseases.

Methylophiopogonanone B of Radix Ophiopogonis protects cells from H2O2‑induced apoptosis through the NADPH oxidase pathway in HUVECs

Methylophiopogonanone B (MO-B), which belongs to a group of homoisoflavonoids, present in Ophiopogon japonicus, has been identified as an active component with antioxidative and anti-tumor properties. The present study investigated whether MO-B may exert protective effects on human umbilical vein endothelial cells (HUVECs) against H₂O₂-induced injury in vitro, and whether the MO-B effects may be modulated by the NADPH pathway. HUVECs were treated with MO-B in the presence or absence of H₂O₂. Malondialdehyde (MDA), reactive oxygen species (ROS) levels, and superoxide dismutase (SOD) activity were analyzed to evaluate cell injury and the antioxidative potential of MO-B. The results revealed that MO-B inhibited the production of MDA and ROS, but enhanced SOD activity. Furthermore, MO-B could alleviate H₂O₂-induced apoptosis in HUVECs, which is consistent with the expression of apoptosis-associated genes and proteins in cells, including Bax/Bcl-2 and caspase-3. To explore the potential mechanism, the present study investigated the effects of MO-B on NADPH-related signaling via the analysis of neutrophil cytochrome b light chain (p22phox) expression, which is the membrane-associated subunit of NADPH oxidase. MO-B could improve the survival of endothelial cells and therefore may be a potential drug in the treatment of cardiovascular diseases.

Halofuginone protects HUVECs from H2O2-induced injury by modulating VEGF/JNK signaling pathway

BACKGROUND

Halofuginone, which is the main active ingredient of Dichroa fabrifuga, was used to inhibit the synthesis of type I collagen and played increasingly important roles in tumor therapy. This study aims to investigate the protective effects of halofuginone on human umbilical vein endothelial cells (HUVECs) from H2O2-induced apoptosis and oxidative stress.

METHODS

Propidium iodide and Annexin-V double staining assay was used to measure the apoptosis. Cell viability assay, the measurements of reactive oxygen species (ROS) parameters malondialdehyde and superoxide dismutase, western-blot assays, and quantitative PCR were used to elucidate the effects and mechanisms of halofuginone in protecting H2O2-induced injury.

RESULTS

The results showed that halofuginone counteracted H2O2-induced cell viability decline and PCNA downregulation. Furthermore, halofuginone decreased ROS levels and protected HUVECs from H2O2-induced apoptosis. In detail, it showed that H2O2 induced a transient activation of Mitogen-activated protein kinases members ERK1/2 and p38, whereas induced a sustained activation of c-Jun N-terminal kinase (JNK), which play dominant roles in triggering apoptosis. Inhibition of JNK activation also inhibited H2O2-mediated apoptosis. Finally, it was shown that halofuginone upregulated VEGF expressions, which functioned by inhibiting sustained JNK activation, thus protecting HUVECs.

CONCLUSION

Halofuginone has powerful effects in protecting HUVECs from H2O2-induced apoptosis, via upregulating VEGF and inhibiting overactivated JNK phosphorylation. Halofuginone might be a promising preventive drug for cardiovascular diseases.

CNDP1, NOS3, and MnSOD Polymorphisms as Risk Factors for Diabetic Nephropathy among Type 2 Diabetic Patients in Malaysia

Type 2 diabetes mellitus (T2DM) is associated with a high incidence of nephropathy. The aim of this study was to investigate the association of a genetic polymorphism of carnosinase (CNDP1-D18S880 and -rs2346061), endothelial nitric oxide synthase (NOS3-rs1799983), and manganese superoxide dismutase (MnSOD-rs4880) genes with the development of diabetic nephropathy among Malaysian type 2 diabetic patients. A case-control association study was performed using 652 T2DM patients comprising 227 Malays (without nephropathy = 96 and nephropathy = 131), 203 Chinese (without nephropathy = 95 and nephropathy = 108), and 222 Indians (without nephropathy = 136 and nephropathy = 86). DNA sequencing was performed for the D18S880 of CNDP1, while the rest were tested using DNA Sequenom MassARRAY to identify the polymorphisms. DNA was extracted from the secondary blood samples taken from the T2DM patients. The alleles and genotypes were tested using four genetic models, and the best mode of inheritance was chosen based on the least p value. The rs2346061 of CNDP1 was significantly associated with diabetic nephropathy among the Indians only with OR = 1.94 and 95% CI = (1.76–3.20) and fitted best the multiplicative model, while D18S880 was associated among all the three major races with the Malays having the strongest association with OR = 2.46 and 95% CI = (1.48–4.10), Chinese with OR = 2.26 and 95% CI = (1.34–3.83), and Indians with OR = 1.77 and 95% CI = (1.18–2.65) in the genotypic multiplicative model. The best mode of inheritance for both MnSOD and NOS3 was the additive model. For MnSOD-rs4880, the Chinese had OR = 2.8 and 95% CI = (0.53–14.94), Indians had OR = 2.4 and 95% CI = (0.69–2.84), and Malays had OR = 2.16 and 95% CI = (0.54–8.65), while for NOS3-rs1799983, the Indians had the highest risk with OR = 3.16 and 95% CI = (0.52–17.56), followed by the Chinese with OR = 3.55 and 95% CI = (0.36–35.03) and the Malays with OR = 2.89 and 95% CI = (0.29–28.32). The four oxidative stress-related polymorphisms have significant effects on the development of nephropathy in type 2 diabetes patients. The genes may, therefore, be considered as risk factors for Malaysian subjects who are predisposed to T2DM nephropathy.

A study of cryogenic tissue-engineered liver slices in calcium alginate gel for drug testing

To address issues such as transportation and the time-consuming nature of tissue-engineered liver for use as an effective drug metabolism and toxicity testing model, "ready-to-use" cryogenic tissue-engineered liver needs to be studied. The research developed a cryogenic tissue-engineered liver slice (TELS), which comprised of HepG2 cells and calcium alginate gel. Cell viability and liver-specific functions were examined after different cryopreservation and recovery culture times. Then, cryogenic TELSs were used as a drug-testing model and treated with Gefitinib. Cryogenic TELSs were stored at -80 °C to ensure high cell viability. During recovery in culture, the cells in the cryogenic TELS were evenly distributed, massively proliferated, and then formed spheroid-like aggregates from day 1 to day 13. The liver-specific functions in the cryogenic TELS were closely related to cryopreservation time and cell proliferation. As a reproducible drug-testing model, the cryogenic TELS showed an obvious drug reaction after treatment with the Gefitinib. The present study shows that the cryopreservation techniques can be used in drug-testing models.

The effect of 12 weeks carnosine supplementation on renal functional integrity and oxidative stress in pediatric patients with diabetic nephropathy: a randomized placebo-controlled trial

BACKGROUND AND OBJECTIVES

Oxidative stress is a significant contributor to the pathogenesis of diabetic nephropathy. Carnosine is a natural radical oxygen species scavenger. We investigated the effect of carnosine as an adjuvant therapy on urinary albumin excretion (UAE), the tubular damage marker alpha 1-microglobulin (A1M), and oxidative stress in pediatric patients with type 1 diabetes and nephropathy.

METHODS

This randomized placebo-controlled trial included 90 patients with diabetic nephropathy, despite oral angiotensin-converting enzyme inhibitors (ACE-Is), who were randomly assigned to receive either 12 weeks of carnosine 1 g/day (n = 45), or matching placebo (n = 45). Both groups were followed-up with assessment of hemoglobin A1c (HbA1c), UAE, A1M, total antioxidant capacity (TAC) and malondialdhyde (MDA).

RESULTS

Baseline clinical and laboratory parameters were consistent between carnosine and placebo groups (P > .05). After 12 weeks, carnosine treatment resulted in significant decrease of HbA1c (8.2 ± 2.1% vs 7.4 ± 1.3%), UAE (91.7 vs 38.5 mg/g creatinine), A1M (16.5 ± 6.8 mg/L vs 9.3 ± 6.6 mg/L), MDA levels (25.5 ± 8.1 vs 18.2 ± 7.7 nmol/mL) while TAC levels were increased compared with baseline levels (P < .001) and compared with placebo (P < .001). No adverse reactions due to carnosine supplementation were reported. Baseline TAC was inversely correlated to HbA1c (r = -0.58, P = .04) and A1M (r = -0.682, P = .015) among carnosine group.

CONCLUSIONS

Oral supplementation with L-Carnosine for 12 weeks resulted in a significant improvement of oxidative stress, glycemic control and renal function. Thus, carnosine could be a safe and effective strategy for treatment of pediatric patients with diabetic nephropathy.

The Effects of Long-Term Chaetomellic Acid A Administration on Renal Function and Oxidative Stress in a Rat Model of Renal Mass Reduction

Purpose. This study aimed to evaluate the effect of chronic treatment with chaetomellic acid A (CAA) on oxidative stress and renal function in a model of renal mass reduction. Methods. Male Wistar rats were subjected to 5/6 nephrectomy (RMR) or sham-operated (SO). One week after surgery, rats have been divided into four experimental groups: RMR: RMR rats without treatment (n = 14); RMR + CAA: RMR rats treated with CAA (n = 13); SO: SO rats without treatment (n = 13); and SO + CAA: SO rats treated with CAA (n = 13). CAA was intraperitoneally administered in a dose of 0.23 µg/Kg three times a week for six months. Results. RMR was accompanied by a significant reduction in catalase and glutathione reductase (GR) activity (p < 0.05) and a decrease in reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio. CAA administration significantly increased catalase and GR activity (p < 0.05) and increased GSH/GSSG ratio, but no significant difference between the treated and nontreated groups was found in this ratio. No significant differences were found between the RMR groups in any of the parameters of renal function. However, CAA administration slightly improves some parameters of renal function. Conclusions. These data suggest that CAA could attenuate 5/6 RMR-induced oxidative stress.

Carnosine ameliorates cognitive deficits in streptozotocin-induced diabetic rats: Possible involved mechanisms

Diabetic patients are at increased risk to develop cognitive deficit and senile dementia. This study was planned to assess the benefits of chronic carnosine administration on prevention of learning and memory deterioration in streptozotocin (STZ)-diabetic rats and to explore some of the involved mechanisms. Rats were divided into 5 groups: i.e., control, carnosine100-treated control, diabetic, and carnosine-treated diabetics (50 and 100mg/kg). Carnosine was injected i.p. at doses of 50 or 100mg/kg for 7 weeks, started 1 week after induction of diabetes using streptozotocin. Treatment of diabetic rats with carnosine at a dose of 100mg/kg at the end of the study lowered serum glucose, improved spatial recognition memory in Y maze, improved retention and recall in elevated plus maze, and prevented reduction of step-through latency in passive avoidance task. Furthermore, carnosine at a dose of 100mg/kg reduced hippocampal acetylcholinesterase (AChE) activity, lowered lipid peroxidation, and improved superoxide dismutase (SOD) activity and non-enzymatic antioxidant defense element glutathione (GSH), but not activity of catalase. Meanwhile, hippocampal level of nuclear factor-kappaB (NF-κB), tumor necrosis factor α (TNF-α), and glial fibrillary acidic protein (GFAP) decreased and level of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase 1 (HO-1) increased upon treatment of diabetic group with carnosine at a dose of 100mg/kg. Taken together, chronic carnosine treatment could ameliorate learning and memory disturbances in STZ-diabetic rats through intonation of NF-κB/Nrf2/HO-1 signaling cascade, attenuation of astrogliosis, possible improvement of cholinergic function, and amelioration of oxidative stress and neuroinflammation.

Inhibition of hydrogen peroxide induced injuring on human skin fibroblast by Ulva prolifera polysaccharide

Ulva prolifera can protect human skin fibroblast from being injured by hydrogen peroxide. This work studied the composition of Ulva prolifera polysaccharide and identified its physicochemical properties. The results showed that the cell proliferation of 0.5mg/mL crude polysaccharide was 154.4% of that in negative control group. Moreover, ROS detection indices, including DCFH-DA, GSH-PX, MDA and CAT, indicated that crude polysaccharide could improve cellular ability to scavenge free radical and decrease the injury on human skin fibroblast by hydrogen peroxide. In purified polysaccharide, the activity of fraction P1-1 was the highest, with 174.6% of that in negative control group. The average molecular weight of P1-1 was 137kD with 18.0% of sulfate content. This work showed the inhibition of hydrogen peroxide induced injuries on human skin fibroblast by Ulva prolifera polysaccharide, which may further evaluate the application of U. prolifera on cosmetics.

Effects of carnosine supplementation on glucose metabolism: Pilot clinical trial

OBJECTIVE

Carnosine is a naturally present dipeptide in humans and an over-the counter food additive. Evidence from animal studies supports the role for carnosine in the prevention and treatment of diabetes and cardiovascular disease, yet there is limited human data. This study investigated whether carnosine supplementation in individuals with overweight or obesity improves diabetes and cardiovascular risk factors.

METHODS

In a double-blind randomized pilot trial in nondiabetic individuals with overweight and obesity (age 43 ± 8 years; body mass index 31 ± 4 kg/m(2) ), 15 individuals were randomly assigned to 2 g carnosine daily and 15 individuals to placebo for 12 weeks. Insulin sensitivity and secretion, glucose tolerance (oral glucose tolerance test), blood pressure, plasma lipid profile, skeletal muscle ((1) H-MRS), and urinary carnosine levels were measured.

RESULTS

Carnosine concentrations increased in urine after supplementation (P < 0.05). An increase in fasting insulin and insulin resistance was hampered in individuals receiving carnosine compared to placebo, and this remained significant after adjustment for age, sex, and change in body weight (P = 0.02, P = 0.04, respectively). Two-hour glucose and insulin were both lower after carnosine supplementation compared to placebo in individuals with impaired glucose tolerance (P < 0.05).

CONCLUSIONS

These pilot intervention data suggest that carnosine supplementation may be an effective strategy for prevention of type 2 diabetes.

Muscle Carnosine Is Associated with Cardiometabolic Risk Factors in Humans

BACKGROUND

Carnosine is a naturally present dipeptide abundant in skeletal muscle and an over-the counter food additive. Animal data suggest a role of carnosine supplementation in the prevention and treatment of obesity, insulin resistance, type 2 diabetes and cardiovascular disease but only limited human data exists.

METHODS AND RESULTS

Samples of vastus lateralis muscle were obtained by needle biopsy. We measured muscle carnosine levels (high-performance liquid chromatography), % body fat (bioimpedance), abdominal subcutaneous and visceral adiposity (magnetic resonance imaging), insulin sensitivity (euglycaemic hyperinsulinemic clamp), resting energy expenditure (REE, indirect calorimetry), free-living ambulatory physical activity (accelerometers) and lipid profile in 36 sedentary non-vegetarian middle aged men (45±7 years) with varying degrees of adiposity and glucose tolerance. Muscle carnosine content was positively related to % body fat (r = 0.35, p = 0.04) and subcutaneous (r = 0.38, p = 0.02) but not visceral fat (r = 0.17, p = 0.33). Muscle carnosine content was inversely associated with insulin sensitivity (r = -0.44, p = 0.008), REE (r = -0.58, p<0.001) and HDL-cholesterol levels (r = -0.34, p = 0.048). Insulin sensitivity and physical activity were the best predictors of muscle carnosine content after adjustment for adiposity.

CONCLUSION

Our data shows that higher carnosine content in human skeletal muscle is positively associated with insulin resistance and fasting metabolic preference for glucose. Moreover, it is negatively associated with HDL-cholesterol and basal energy expenditure. Intervention studies targeting insulin resistance, metabolic and cardiovascular disease risk factors are necessary to evaluate its putative role in the prevention and management of type 2 diabetes and cardiovascular disease.