Impaired humoral immunity following COVID-19 vaccination in HTLV-1 carriers.

BACKGROUND: Whether human T-lymphotropic virus type 1 (HTLV-1) carriers can develop sufficient humoral immunity after coronavirus disease 2019 (COVID-19) vaccination is unknown. METHODS: To investigate humoral immunity after COVID-19 vaccination in HTLV-1 carriers, a multicenter, prospective observational cohort study was conducted at five institutions in southwestern Japan, an endemic area for HTLV-1. HTLV-1 carriers and HTLV-1-negative controls were enrolled for this study from January to December 2022. During this period, the third dose of the COVID-19 vaccine was actively administered. HTLV-1 carriers were enrolled during outpatient visits, while HTLV-1-negative controls included health care workers and patients treated by participating institutions for diabetes, hypertension, or dyslipidemia. The main outcome was the effect of HTLV-1 infection on the plasma anti-COVID-19 spike IgG (IgG-S) titers after the third dose, assessed by multivariate linear regression with other clinical factors. RESULTS: We analyzed 181 cases (90 HTLV-1 carriers, 91 HTLV-1-negative controls) after receiving the third dose. HTLV-1 carriers were older (median age 67.0 vs. 45.0 years, p < 0.001) and more frequently had diabetes, hypertension, or dyslipidemia than did HTLV-1-negative controls (60.0% vs. 27.5%, p < 0.001). After the third dose, the IgG-S titers decreased over time in both carriers and controls. Multivariate linear regression in the entire cohort showed that time since the third dose, age, and HTLV-1 infection negatively influenced IgG-S titers. After adjusting for confounders such as age, or presence of diabetes, hypertension, or dyslipidemia between carriers and controls using the overlap weighting propensity score method, and performing weighted regression analysis in the entire cohort, both time since the third dose and HTLV-1 infection negatively influenced IgG-S titers. CONCLUSIONS: The humoral immunity after the third vaccination dose is impaired in HTLV-1 carriers; thus, customized vaccination schedules may be necessary for them.

Impact of the lipase inhibitor orlistat on the human gut microbiota.

Orlistat, an anti-obesity agent, inhibits the metabolism and absorption of dietary fat by inactivating pancreatic lipase in the gut. The effect of orlistat on the gut microbiota of Japanese individuals with obesity is unknown. This study aimed to explore the effects of orlistat on the gut microbiota and fatty acid metabolism of Japanese individuals with obesity. Fourteen subjects with visceral fat obesity (waist circumference ≥85 cm) took orlistat orally at a dose of 60 mg, 3 times a day for 8 weeks. Body weight; waist circumference; visceral fat area; levels of short-chain fatty acids, gut microbiota, fatty acid metabolites in the feces, and gastrointestinal hormones; and adverse events were evaluated. Body weight, waist circumference, and blood leptin concentrations were significantly lower after orlistat treatment (mean ± standard deviation, 77.8 ± 9.1 kg; 91.9 ± 8.7 cm; and 4546 ± 3211 pg/mL, respectively) compared with before treatment (79.4 ± 9.0 kg; 94.4 ± 8.0 cm; and 5881 ± 3526 pg/mL, respectively). Significant increases in fecal levels of fatty acid metabolites (10-hydroxy-cis-12-octadecenoic acid, 10-oxo-cis-12-octadecenoic acid, and 10-oxo-trans-11-octadecenoic acid) were detected. Meanwhile, no significant changes were found in abdominal computed tomography parameters, blood marker levels, or short-chain fatty acid levels in the feces. Gut microbiota analysis revealed that some study subjects had decreased abundance of Firmicutes, increased abundance of Bacteroidetes, and increased α-diversity indices (Chao1 and ACE) after 8 weeks of treatment. The levels of Lactobacillus genus and Lactobacillus gasseri were significantly higher after 8 weeks of treatment. None of the subjects discontinued treatment or experienced severe adverse events. This study suggested that orlistat might alter gut microbiota composition and affect the body through fatty acid metabolites produced by the modified gut bacteria.

Association between personality traits and glycemic control after inpatient diabetes education.

Aims: The longitudinal effect of personality traits on glycemic control is unclear. This prospective observational study explored the relationship between personality traits and glycemic control in patients with uncontrolled diabetes after inpatient diabetes education. Methods: Patients with diabetes mellitus (HbA1c ≥ 7.5%, measured by high-performance liquid chromatography) who received inpatient diabetes education were scored on the Big Five personality traits: neuroticism, extraversion, openness, agreeableness, and conscientiousness. Multiple linear analysis was used to determine whether any personality traits were independently associated with HbA1c on admission and HbA1c change from admission to 1, 3, and 6 months after discharge. Results: One hundred seventeen participants (mean age 60.4 ± 14.5 years; 59.0% male) were enrolled. HbA1c values on admission and 1, 3, and 6 months after discharge were 10.2 ± 2.1%, 8.3 ± 1.4%, 7.6 ± 1.4%, and 7.7 ± 1.5%, respectively. Multiple linear analysis showed that no personality traits were associated with HbA1c on admission. Neuroticism was negatively associated with the HbA1c change from admission to 3 months (ß = -0.192, P = 0.025) and 6 months after discharge (ß = -0.164, P = 0.043). Conclusions: Neuroticism was associated with good long-term glycemic control after inpatient diabetes education.

Association of Serum Levels of Cholesterol Absorption and Synthesis Markers with the Presence of Cardiovascular Disease: The CACHE Study CVD Analysis.

AIM: Serum levels of cholesterol absorption and synthesis markers have been associated with cardiovascular risk in the United States and European countries. In this study, we examined the relevance of these biomarkers and the presence of cardiovascular disease (CVD) in Japanese individuals. METHODS: The CACHE consortium, comprising of 13 research groups in Japan possessing data on campesterol, an absorption marker, and lathosterol, a synthesis marker measured by gas chromatography, compiled the clinical data using the REDCap system. RESULTS: Among the 2,944 individuals in the CACHE population, those with missing campesterol or lathosterol data were excluded. This cross-sectional study was able to analyze data from 2,895 individuals, including 339 coronary artery disease (CAD) patients, 108 cerebrovascular disease (CeVD) patients, and 88 peripheral artery disease (PAD) patients. The median age was 57 years, 43% were female, and the median low-density lipoprotein cholesterol and triglyceride levels were 118 mg/dL and 98 mg/dL, respectively. We assessed the associations of campesterol, lathosterol, and the ratio of campesterol to lathosterol (Campe/Latho ratio) with the odds of CVD using multivariable-adjusted nonlinear regression models. The prevalence of CVD, especially CAD, showed positive, inverse, and positive associations with campesterol, lathosterol, and the Campe/Latho ratio, respectively. These associations remained significant even after excluding individuals using statins and/or ezetimibe. The associations of the cholesterol biomarkers with PAD were determined weaker than those with CAD. Contrarily, no significant association was noted between cholesterol metabolism biomarkers and CeVD. CONCLUSION: This study showed that both high cholesterol absorption and low cholesterol synthesis biomarker levels were associated with high odds of CVD, especially CAD.

Improving the Effects of Imeglimin on Endothelial Function: A Prospective, Single-Center, Observational Study.

INTRODUCTION: Endothelial dysfunction is a risk factor for cardiovascular disease in patients with diabetes. We hypothesized that imeglimin, a novel oral hypoglycemic agent, would improve endothelial function. METHODS: In this study, imeglimin was administered to patients with type 2 diabetes and HbA1c ≥ 6.5% who were not receiving insulin therapy. A meal tolerance test (592 kcal, glucose 75.0 g, fat 28.5 g) was performed before and 3 months after administration, and endothelial function, blood glucose, insulin, glucagon, and triglycerides were evaluated. Endothelial function was assessed by flow-mediated dilation (FMD). RESULTS: Twelve patients (50% male) with a median age of 55.5 years old (interquartile range [IQR] 51.3-66.0) were enrolled. Fasting FMD did not differ before or 3 months after imeglimin administration (from 6.1 [3.9-8.5] to 6.6 [3.9-9.0], p = 0.092), but 2 h postprandial FMD was significantly improved 3 months after imeglimin administration (from 2.3 [1.9-3.4] to 2.9 [2.4-4.7], p = 0.013). In terms of the glucose profile, imeglimin administration significantly improved HbA1c (from 7.2 ± 0.6% to 6.9 ± 0.6%, p = 0.007), fasting glucose (from 138 ± 19 mg/dL to 128 ± 20 mg/dL, p = 0.020), and 2 h postprandial glucose (from 251 ± 47 mg/dL to 215 ± 68 mg/dL, p = 0.035). The change in 2 h postprandial FMD between before and 3 months after imeglimin administration (Δ2 h postprandial FMD) was negatively correlated with Δ2 h postprandial glucose (r = - 0.653, p = 0.021) in a univariate correlation coefficient analysis. Both patients with and without decreased postprandial glucose 3 months after imeglimin administration had improved postprandial FMD. CONCLUSION: In this small study, imeglimin administration improved 2 h postprandial FMD. Both glycemic control-dependent and -independent mechanisms might contribute to improved endothelial function. TRIAL REGISTRATION: This research was registered in the University Hospital Medical Information Network (UMIN, UMIN000046311).

Serum Values of Cholesterol Absorption and Synthesis Biomarkers in Japanese Healthy Subjects: The CACHE Study HEALTHY Analysis.

AIM: Blood cholesterol absorption and synthesis biomarkers predict cardiovascular risk. This study aimed to determine the values of serum non-cholesterol sterol markers [lathosterol (Latho), campesterol (Campe), and sitosterol (Sito)] in healthy individuals and factors affecting these markers. METHODS: The CACHE Consortium compiled clinical data, including serum Latho (cholesterol synthesis marker), and Campe and Sito (cholesterol absorption markers), by a gas chromatography method in 2944 individuals. Healthy subjects were selected by excluding those with prior cardiovascular disease, diabetes mellitus, hypertension, chronic kidney disease, familial hypercholesterolemia, sitosterolemia, current smokers, those with low (＜17 kg/m2) or high (≥ 30 kg/m2) body mass index (BMI), and those with treatment for dyslipidemia or hyperuricemia. Nonlinear regression stratified by sex was used to examine the associations of cholesterol metabolism markers with age, BMI, and serum lipid levels. RESULTS: Of 479 individuals selected, 59.4% were female; the median age was 48 years in females and 50 years in males. The three markers showed positively skewed distributions, and sex differences were present. Age was associated positively with Latho, inversely with Campe, but not significantly with Sito. BMI was associated positively with Latho, but not significantly with Campe or Sito. High-density lipoprotein cholesterol (HDL-C) was positively associated with Campe and Sito, but not significantly with Latho. Non-HDL-C was positively associated with the three markers. CONCLUSION: Our study results in the healthy subjects help to interpret the non-cholesterol sterol markers for cardiovascular risk assessment in patients with cardiovascular risk factors.

Association between Familial Hypercholesterolemia and Serum Levels of Cholesterol Synthesis and Absorption Markers: The CACHE Study FH Analysis.

AIM: Serum levels of cholesterol absorption and synthesis markers are known to be associated with cardiovascular risk. Familial hypercholesterolemia (FH) is a well-known inherited disorder presenting elevated low-density lipoprotein cholesterol (LDL-C) and total cholesterol (TC) levels and premature coronary disease. In this study, we aim to examine the differences in terms of serum markers of cholesterol metabolism between FH and non-FH individuals and to examine their associations with serum lipid levels. METHODS: In this study, we utilized data on serum markers of cholesterol metabolism, namely, lathosterol (Latho, synthesis marker), campesterol (Campe, absorption marker), and sitosterol (Sito, absorption marker) measured by gas chromatography of the CACHE consortium, which comprised of 13 research groups in Japan. Clinical data were compiled using REDCap system. Among the 2944 individuals in the CACHE population, we selected individuals without lipid-lowering medications and hemodialysis patients for this CACHE study FH analysis. Multivariable adjustment was performed to assess the associations. RESULTS: In this study, we analyzed data from 51 FH patients and 1924 non-FH individuals. After adjustment for possible confounders, the FH group was shown to have significantly higher Campe and Sito concentrations and insignificantly higher Latho concentrations than the non-FH group. These marker concentrations showed nonlinear associations with TC in the FH group. Campe/Latho and Sito/Latho ratios were significantly higher in the FH group than in the non-FH group. CONCLUSION: FH group had significantly elevated serum Campe and Sito concentrations and insignificantly elevated Latho concentrations; thus, intestinal cholesterol absorption relative to hepatic cholesterol synthesis was suggested to be elevated in patients with FH. Serum Latho, Campe, and Sito concentrations showed nonlinear associations with TC in the FH group.

Active Consumption of Konjac and Konjac Products Improves Blood Glucose Control in Patients with Type 2 Diabetes Mellitus.

OBJECTIVE: Konjac is a food mainly consumed in Asian countries with high fiber and low energy. Although glucomannan, a component of konjac, have been used for several clinical studies, there is few reports using konjac itself. This study examined the effects of the active consumption of konjac in patients with type 2 diabetes mellitus (T2DM). METHODS: The study included 26 Japanese patients with T2DM. Participants were recommended to take konjac at least once a day using free konjac products (various noodles, rice, and desserts) and plate konjac for 12 weeks. RESULTS: HbA1c and fasting plasma glucose levels significantly decreased from 8.3 ± 0.9% to 8.0 ± 0.8% and from 173.2 ± 44.4 to 152.8 ± 36.7 mg/dL, respectively. No significant changes were observed in body weight and insulin resistance indices, but the index for insulin secretion significantly increased. Serum high molecular weight adiponectin levels significantly increased. Plasma ghrelin, leptin and glucagon-like peptide-1 levels tended to decrease (p = 0.084), decrease (p = 0.057) and increase (p = 0.071), respectively. Actual konjac intake positively correlated with age (r = 0.61, p = 0.001). Body weight and HbA1c significantly decreased in patients aged ≥50 years than in those aged <50 years, and the changes significantly inversely correlated with age. CONCLUSION: Active consumption of konjac and konjac products seems to be a useful dietary therapy with multifaceted action for T2DM. Further studies with greater sample size and long-term are needed to confirm these findings.

Relationship between Diabetes Mellitus and Serum Lathosterol and Campesterol Levels: The CACHE Study DM Analysis.

AIM: Risk of cardiovascular disease is increased in patients with diabetes mellitus (DM). Cholesterol metabolism (hepatic synthesis and intestinal absorption) is known to be associated with cardiovascular risk. Next, we examined the association of DM with cholesterol absorption/synthesis. METHODS: The CACHE Consortium, which is comprised of 13 research groups in Japan possessing data of lathosterol (Latho, synthesis marker) and campesterol (Campe, absorption marker) measured by gas chromatography, compiled the clinical data using the REDCap system. Among the 3597 records, data from 2944 individuals were used for several analyses including this study. RESULTS: This study analyzed data from eligible 2182 individuals including 830 patients with DM; 42.2% were female, median age was 59 years, and median HbA1c of patients with DM was 7.0%. There was no difference in Latho between DM and non-DM individuals. Campe and Campe/Latho ratio were significantly lower in DM individuals than in non-DM individuals. When the associations of glycemic control markers with these markers were analyzed with multivariable-adjusted regression model using restricted cubic splines, Campe and Campe/Latho ratio showed inverse associations with glucose levels and HbA1c. However, Latho showed an inverted U-shaped association with plasma glucose, whereas Latho showed a U-shaped association with HbA1c. These associations remained even after excluding statin and/or ezetimibe users. CONCLUSION: We demonstrated that DM and hyperglycemia were independent factors for lower cholesterol absorption marker levels regardless of statin/ezetimibe use.

Regulation of feeding and therapeutic application of bioactive peptides.

Obesity and obesity-related diseases, such as diabetes mellitus and dyslipidemia, are worldwide pandemics; therefore, studies have been conducted energetically to elucidate the mechanism of obesity and develop anti-obesity drugs. Robust progress in the peptide chemistry and molecular biology has identified many peptides that regulate appetite and energy metabolism over the past dozen years. Several drugs, such as analogs or receptor agonists of anorectic peptides, have been developed. Overall, peptide-related drugs have powerful anti-obesity effects with fewer adverse effects than previous anti-obesity drugs. Liraglutide, a glucagon-like peptide-1 receptor agonist, was first used as an antidiabetic drug, and then high-dose liraglutide was used as an anti-obesity drug. Several candidates have been developed to explore their anti-obesity effects. Additionally, hybrid peptides consisting of two or more peptide sequences with strong anorectic effects have been designed. Here, we review peptides that are important for feeding regulation in terms of their mechanisms of action, interactions, and clinical application as anti-obesity drugs.

Association of Kidney Function with Serum Levels of Cholesterol Absorption and Synthesis Markers: The CACHE Study CKD Analysis.

AIM: Serum levels of cholesterol absorption and synthesis markers are known to be associated with cardiovascular risk. Individuals with reduced kidney function or chronic kidney disease (CKD) are at an increased risk for cardiovascular disease. Hence, we examined the relationship between estimated glomerular filtration rate (eGFR) and serum markers of cholesterol absorption and synthesis. METHODS: The CACHE (Cholesterol Absorption and Cholesterol synthesis in High-risk patiEnts) Consortium, comprised of 13 research groups in Japan possessing data of lathosterol (Latho, synthesis marker) and campesterol (Campe, absorption marker) measured via gas chromatography, compiled the clinical data using the REDCap system. Among the 3597 records, data from 2944 individuals were utilized for five analyses including this CKD analysis. RESULTS: This study analyzed data from 2200 individuals including 522 hemodialysis patients; 42.3% were female, the median age was 58 years, and the median eGFR was 68.9 mL/min/1.73 m2. Latho, Campe, and Campe/Latho ratio were significantly different when compared across CKD stages. When the associations of eGFR with these markers were assessed with multivariable nonlinear regression models, Latho, Campe, and Campe/Latho ratio showed positive, inverse, and inverse associations with eGFR. These associations were significantly modified by sex, the presence/absence of diabetes mellitus, and the presence/absence of statin use. CONCLUSION: We showed that individuals with lower eGFR have lower cholesterol synthesis marker levels and higher cholesterol absorption marker levels in this large sample.

Current status of diabetes treatment in Miyazaki Prefecture, Japan: Results of a questionnaire survey conducted in 2016 and 2020.

AIMS/INTRODUCTION: The Japanese diabetes treatment guidelines do not specify the first choice of hypoglycemic agents, unlike those of Western countries. Furthermore, the current situation in diabetes treatment is that the choice of hypoglycemic agents is determined by each physician. Therefore, we aimed to determine the current situation in Miyazaki Prefecture, Japan, in this context. For this, we carried out a questionnaire survey among physicians twice regarding the target value of glycated hemoglobin and the choice of hypoglycemic agents in various cases. MATERIALS AND METHODS: We administered an unsigned questionnaire to physicians in Miyazaki Prefecture, Japan, in July 2016 and March 2020. We divided responses into those of diabetologists and those of non-diabetologists, and analyzed each response. We then compared the results between both years. RESULTS: In total, 18 diabetologists and 142 non-diabetologists responded in 2016, and 21 diabetologists and 134 non-diabetologists responded in 2020. Many diabetologists chose biguanide as the first-line drug for obese type 2 diabetes patients. In addition, the rate of choice of sodium-glucose cotransporter 2 inhibitor (SGLT2i) among physicians almost increased in 2020. Some non-diabetologists, and even a few diabetologists, inappropriately chose SGLT2i and biguanide for patients with severe renal dysfunction. CONCLUSIONS: Because SGLT2i became available in 2016 and a few years have passed, both diabetologists and non-diabetologists seemed to refrain from prescribing SGLT2i. However, with the emergence of various lines of firm evidence regarding the use of SGLT2i, physicians started to prescribe it. However, some diabetologists and non-diabetologists chose hypoglycemic agents inadequately; therefore, there is a need for novel and precise information.

Concurrent Use of Teneligliptin and Canagliflozin Improves Glycemic Control with Beneficial Effects on Plasma Glucagon and Glucagon-Like Peptide-1: A Single-Arm Study.

INTRODUCTION: We investigated the mechanisms of the glucose-lowering effects of teneligliptin and canagliflozin, a sodium-glucose cotransporter-2 (SGLT2) inhibitor, by monitoring several gastrointestinal peptides using the most appropriate measuring methods during multiple meal tolerance tests (MTTs) and flash glucose monitoring. METHODS: Twelve Japanese patients with type 2 diabetes were enrolled in the 14-day study. Subjects were treated with teneligliptin 20 mg/day from day 4, followed by a combination tablet of teneligliptin 20 mg and canagliflozin 100 mg (T/C) per day from day 11. MTTs were conducted on days 3 (premedication; Pre), 10 (teneligliptin; T) and 13 (T/C) to evaluate plasma glucose, C-peptide, glucagon, active glucagon-like peptide-1 (GLP-1), active gastric inhibitory polypeptide (GIP), ghrelin and des-acyl ghrelin. RESULTS: Plasma glucose was significantly decreased with the progress of treatment intervention, and C-peptide was significantly decreased in T/C compared to the others. Plasma postprandial glucagon was increased for 90 min from fasting in Pre, but only for 30 min in T and T/C. Plasma postprandial active GLP-1 was significantly increased in T compared to Pre, and that of T/C was significantly higher than T. Plasma postprandial active GIP was increased in T and T/C compared to Pre. Plasma ghrelin and des-acyl ghrelin levels did not change during the treatment. CONCLUSION: Teneligliptin increased incretin hormones and suppressed postprandial glucagon secretion as expected. Concurrent use of canagliflozin and teneligliptin improved glycemic control without increasing postprandial glucagon secretion, and increased postprandial GLP-1 secretion and decreased the required amount of postprandial insulin secretion. The underlying mechanisms may involve canagliflozin's inhibitory activity against not only SGLT2 but also SGLT1. TRIAL REGISTRATION: UMIN identifier, UMIN000030043. FUNDING: Mitsubishi Tanabe Pharma Corporation and a Grant for Clinical Research from Miyazaki University Hospital.

Effects of Ipragliflozin on Postprandial Glucose Metabolism and Gut Peptides in Type 2 Diabetes: A Pilot Study.

INTRODUCTION: Ipragliflozin is a novel antidiabetic drug that inhibits renal tubular sodium-glucose cotransporter-2 (SGLT2). The aim of this study was to evaluate the effects of ipragliflozin on glucose, insulin, glucagon, and gastrointestinal peptide responses to a meal tolerance test, as well as to investigate the glucose-lowering mechanisms of ipragliflozin. METHODS: Nine Japanese patients with obesity and type 2 diabetes mellitus were treated with ipragliflozin (50 mg/day) for 12 weeks. The postprandial profiles of glucose, insulin, glucagon, active glucagon-like peptide-1 (GLP-1), active glucose-dependent insulinotropic polypeptide (GIP), ghrelin, and des-acyl ghrelin were measured before and 12 weeks after ipragliflozin treatment. RESULTS: Body weight, body fat mass, systolic blood pressure, and HbA1c and serum uric acid levels were significantly decreased after the treatment. Postprandial glucose and insulin levels were also significantly decreased. Postprandial glucagon increased both before and after ipragliflozin treatment; however, the increment tended to be smaller after treatment. Active GLP-1, active GIP, ghrelin, and des-acyl ghrelin did not change after treatment. CONCLUSION: Ipragliflozin improved glycemic control by reducing body weight, postprandial inappropriate glucagon secretion, and the postprandial insulin requirement. Although this was a short-term study with a small sample size, ipragliflozin may offer benefits for patients with obesity and type 2 diabetes mellitus. TRIAL REGISTRATION: University Hospital Medical Information Network (UMIN No. 000017195).

Ghrelin alleviates paclitaxel-induced peripheral neuropathy by reducing oxidative stress and enhancing mitochondrial anti-oxidant functions in mice.

Paclitaxel is an effective chemotherapeutic agent, but has some treatment-limiting adverse effects that markedly decrease patients' quality of life. Peripheral neuropathy is one of these, and no treatment for it has been established yet. Ghrelin, an endogenous ligand for the growth hormone secretagogue receptor, is secreted from the stomach and has widespread effects on multiple systems. We investigated the pharmacological potential of ghrelin in preventing paclitaxel-induced peripheral neuropathy using wild-type mice, ghrelin-null mice, and growth hormone secretagogue receptor-null mice. In wild-type mice, ghrelin administration alleviated mechanical and thermal hypersensitivity, and partially prevented neuronal loss of small unmyelinated intraepidermal nerve fibers but not large myelinated nerve fibers. Moreover, ghrelin administration decreased plasma oxidative and nitrosative stress and increased the expression of uncoupling protein 2 (UCP2) and superoxide dismutase 2 (SOD2) in the dorsal root ganglia, which are mitochondrial antioxidant proteins, and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), a regulator of mitochondrial number. Both ghrelin-null mice and growth hormone secretagogue receptor-null mice developed more severe nerve injuries than wild-type mice. Our results suggest that ghrelin administration exerts a protective effect against paclitaxel-induced neuropathy by reducing oxidative stress and enhancing mitochondrial anti-oxidant functions, and that endogenous ghrelin has a neuroprotective effect that is mediated by ghrelin/growth hormone secretagogue receptor signaling. Ghrelin could be a promising therapeutic agent for the management of this intractable disease.

Clinical application of ghrelin for diabetic peripheral neuropathy.

Diabetic peripheral neuropathy (DPN) is the most common complication of diabetes, and its progression significantly worsens the patient's quality of life. Although several drugs are available for DPN, all of these provide only symptomatic relief. We investigated the therapeutic effects of ghrelin for DPN, based on its various physiological functions. Seven patients with type 2 diabetes with typical clinical signs and symptoms of DPN were hospitalized. Synthetic human ghrelin (1.0 µg/kg) was administered intravenously for 14 days. Motor nerve conduction velocity (MCV) of the posterior tibial nerve improved significantly after the treatment, compared to that at baseline (35.1 ± 1.8 to 38.6 ± 1.8 m/s, p < 0.0001), while the MCV in six untreated patients did not change throughout hospitalization. The subjective symptoms assessed based on the total symptom score also significantly improved (15.6 ± 3.1 to 11.1 ± 2.2, p = 0.047). Although sensory nerve conduction velocity (SCV) of the sural nerve could not be detected in three patients at baseline, it was detected in two of the three patients after 14 days of ghrelin administration. Overall, SCV did not change significantly. Plasma glucose, but not serum C peptide, levels during a liquid meal tolerance test significantly improved after treatment. These results suggest that ghrelin may be a novel therapeutic option for DPN; however, a double-blind, placebo-controlled trial is needed in the future.

Allosteric regulation by cooperative conformational changes of actin filaments drives mutually exclusive binding with cofilin and myosin.

Heavy meromyosin (HMM) of myosin II and cofilin each binds to actin filaments cooperatively and forms clusters along the filaments, but it is unknown whether the two cooperative bindings are correlated and what physiological roles they have. Fluorescence microscopy demonstrated that HMM-GFP and cofilin-mCherry each bound cooperatively to different parts of actin filaments when they were added simultaneously in 0.2 µM ATP, indicating that the two cooperative bindings are mutually exclusive. In 0.1 mM ATP, the motor domain of myosin (S1) strongly inhibited the formation of cofilin clusters along actin filaments. Under this condition, most actin protomers were unoccupied by S1 at any given moment, suggesting that transiently bound S1 alters the structure of actin filaments cooperatively and/or persistently to inhibit cofilin binding. Consistently, cosedimentation experiments using copolymers of actin and actin-S1 fusion protein demonstrated that the fusion protein affects the neighboring actin protomers, reducing their affinity for cofilin. In reciprocal experiments, cofilin-actin fusion protein reduced the affinity of neighboring actin protomers for S1. Thus, allosteric regulation by cooperative conformational changes of actin filaments contributes to mutually exclusive cooperative binding of myosin II and cofilin to actin filaments, and presumably to the differential localization of both proteins in cells.

Mechanistic relationship between the vagal afferent pathway, central nervous system and peripheral organs in appetite regulation.

The hypothalamus is a center of food intake and energy metabolism regulation. Information signals from peripheral organs are mediated through the circulation or the vagal afferent pathway and input into the hypothalamus, where signals are integrated to determine various behaviors, such as eating. Numerous appetite-regulating peptides are expressed in the central nervous system and the peripheral organs, and interact in a complex manner. Of such peptides, gut peptides are known to bind to receptors at the vagal afferent pathway terminal that extend into the mucosal layer of the digestive tract, modulate the electrical activity of the vagus nerve, and subsequently send signals to the solitary nucleus and furthermore to the hypothalamus. All peripheral peptides other than ghrelin suppress appetite, and they synergistically suppress appetite through the vagus nerve. In contrast, the appetite-enhancing peptide, ghrelin, antagonizes the actions of appetite-suppressing peptides through the vagus nerve, and appetite-suppressing peptides have attenuated effects in obesity as a result of inflammation in the vagus nerve. With greater understanding of the mechanism for food intake and energy metabolism regulation, medications that apply the effects of appetite-regulating peptides or implantable devices that electrically stimulate the vagus nerve are being investigated as novel treatments for obesity in basic and clinical studies.

Is ghrelin a glucagon-like peptide-1 secretagogue?

Ghrelin was reported to enhance GLP-1 secretion after glucose load in mice.