Glucose/galactose malabsorption caused by a defect in the Na+/glucose cotransporter

Molecular characterization and function of sodium-dependent glucose transporter 1 in postprandial glucose homeostasis in Macrobrachium rosenbergii

Aquatic animals often exhibit glucose intolerance following a glucose load, and understanding the mechanisms of glucose uptake is crucial for elucidating the underlying processes. Sodium-dependent glucose transporter 1 (SGLT1) plays a crucial role in the process of intestinal glucose absorption and transport in vertebrates, but there is limited information about its function in crustaceans. This study identified the SGLT1 gene (named MrSGLT1) from Macrobrachium rosenbergii. The full cDNA sequence is 3764 bp, encoding 903 amino acids. Unlike SGLT1 in most teleost fish, which have 14 transmembrane domains, MrSGLT1 protein has only 12. MrSGLT1 was predominantly expressed in the intestine, with its expression increasing after feeding. This was accompanied by elevated levels of glucose and trehalose in the hemolymph, and increased glycogen levels in the hepatopancreas. Silencing MrSGLT1 in vivo resulted in decreased glucose and trehalose levels in the hemolymph and reduced glycogen levels in the hepatopancreas, although muscle glycogen levels were unaffected. Moreover, knockdown of MrSGLT1 led to increased expression of genes involved in glycogenolysis and decreased expression of genes associated with glycogenesis, inhibiting postprandial glycogen accumulation in the hepatopancreas. Feeding-induced glycolysis was also inhibited following MrSGLT1 silencing, while no significant changes were observed in gluconeogenesis-related genes. These findings highlight the critical role of MrSGLT1 in regulating postprandial glucose homeostasis in crustaceans.

Effects of sotagliflozin on kidney and cardiac outcome in a hypertensive model of subtotal nephrectomy in male mice

Dual inhibition of sodium glucose cotransporters 1 and 2 (SGLT1/SGLT2) by sotagliflozin protects the kidney and heart in patients with type 2 diabetes mellitus (T2DM) and chronic kidney disease (CKD). To gain mechanistic insights, the current study aimed to establish a murine model of hypertensive CKD that shows cardio-renal protection by sotagliflozin. Since protection by SGLT2 inhibitors can be diabetes-independent, a nondiabetic murine model of subtotal nephrectomy with angiotensin II infusion-facilitated hypertension was followed for 7 weeks. The model showed 40% lower GFR, doubling in plasma FGF23, 50 mmHg higher systolic blood pressure (SBP), 100-fold increased albuminuria, and robust signs of kidney injury, inflammation, and fibrosis versus sham controls, associated with a 30% larger left cardiac ventricle and wall thickness and upregulation of markers of cardiac overload and fibrosis. Sotagliflozin, initiated 1 week after the last surgery, showed target-engagement evidenced by glucosuria, 9 mmHg lower SBP, temporal reduction in body weight and GFR, and 30% higher plasma GLP1. Sotagliflozin, however, did not improve markers of kidney injury, inflammation, fibrosis, albuminuria, and plasma FGF23, or signs of cardiac overload, fibrosis, or impaired function. Limited sotagliflozin responsiveness may relate to short treatment time, limited metabolic benefits in nondiabetic setting and/or the model's dominant angiotensin II-driven effects/hypertension.

Meta-analysis of sotagliflozin, a dual sodium-glucose-cotransporter 1/2 inhibitor, for heart failure in type 2 diabetes

Sodium-glucose co-transporters (SGLTs) mediate sodium and glucose transport across cell membranes. SGLT2 inhibitors have a recognized place within heart failure (HF) guidelines. We evaluated the effect of sotagliflozin on HF and cardiovascular outcomes in participants with type 2 diabetes. Scopus, Medline, Embase and Central were searched from inception until 2 June 2023. Randomized controlled trials evaluating sotagliflozin in type 2 diabetes participants and reporting HF events were selected. Major adverse cardiovascular events (MACE) and systolic blood pressure were evaluated. The Cochrane risk of bias tool (RoB 2.0) was used. Pooled mean difference (MD), relative risk (RR), 95% confidence intervals and the number needed to treat (NNT) were estimated (PROSPERO: CRD42023432732). We selected nine studies (n = 15 320 participants: n = 8040 intervention and n = 7280 control). The median follow-up was 13.4 months (Q1 = 13, Q3 = 21). One study recruited participants with HF at baseline. After a follow-up of >52 weeks, sotagliflozin significantly reduced the risk of HF [n = 8 studies; RR = 0.66 (0.64, 0.69)], stroke [n = 6 studies; RR = 0.75 (0.58, 0.97)] and MACE [n = 8 studies; RR = 0.73 (0.66, 0.81)]. The NNT was 20 and 26 for HF and MACE, respectively. Sotagliflozin lowered systolic blood pressure [n = 7; MD = -2.38 mmHg (-2.79, -1.97)]. No dose-dependent effect was identified for HF [200 mg: RR = 0.38 (0.16, 0.89), 400 mg: RR = 0.57 (0.39, 0.85), P-value = 0.22]. The high risk of bias was a limitation of this review. Sotagliflozin reduced HF and cardiovascular events in type 2 diabetes participants. Research exploring its effects in HF and comparisons with SGLT2 inhibitors is warranted to determine if dual SGLT inhibition surpasses selective inhibition.

Renal glucosuria in children

The kidneys play a critical role in maintaining glucose homeostasis. Under normal renal tubular function, most of the glucose filtered from the glomeruli is reabsorbed in the proximal tubules, leaving only trace amounts in the urine. Glycosuria can occur as a symptom of generalized proximal tubular dysfunction or when the reabsorption threshold is exceeded or the glucose threshold is reduced, as seen in familial renal glycosuria (FRG). FRG is characterized by persistent glycosuria despite normal blood glucose levels and tubular function and is primarily associated with mutations in the sodium/glucose cotransporter 5A2 gene, which encodes the sodium-glucose cotransporter (SGLT) 2. Inhibiting SGLTs has been proposed as a novel treatment strategy for diabetes, and since FRG is often considered an asymptomatic and benign condition, it has inspired preclinical and clinical studies using SGLT2 inhibitors in type 2 diabetes. However, patients with FRG may exhibit clinical features such as lower body weight or height, altered systemic blood pressure, diaper dermatitis, aminoaciduria, decreased serum uric acid levels, and hypercalciuria. Further research is needed to fully understand the pathophysiology, molecular genetics, and clinical manifestations of renal glucosuria.

The molecular mechanism underlying the human glucose facilitators inhibition

Glucose is the primary energy substrate and an essential precursor for cellular metabolism. Maintaining glucose homeostasis necessitates the presence of glucose transporters, as the hydrophilic nature of glucose prevents its passage across the cell membrane. The GLUT family is a crucial group of glucose transporters that facilitate glucose diffusion along the transmembrane glucose concentration gradient. Dysfunction in GLUTs is associated with diseases, such as GLUT1 deficiency syndrome, Fanconi-Bickel syndrome, and type 2 diabetes. Furthermore, elevated expression of GLUTs fuels aerobic glycolysis, known as the Warburg effect, in various types of cancers, making GLUT isoforms possible targets for antineoplastic therapies. To date, 30 GLUT and homolog structures have been released on the Protein Data Bank (PDB), showcasing multiple conformational and ligand-binding states. These structures elucidate the molecular mechanisms underlying substrate recognition, the alternating access cycle, and transport inhibition. Here, we summarize the current knowledge of human GLUTs and their role in cancer, highlighting recent advances in the structural characterization of GLUTs. We also compare the inhibition mechanisms of exofacial and endofacial GLUT inhibitors, providing insights into the design and optimization of GLUT inhibitors for therapeutic applications.

Improvement of Theaflavins on Glucose and Lipid Metabolism in Diabetes Mellitus

In diabetes mellitus, disordered glucose and lipid metabolisms precipitate diverse complications, including nonalcoholic fatty liver disease, contributing to a rising global mortality rate. Theaflavins (TFs) can improve disorders of glycolipid metabolism in diabetic patients and reduce various types of damage, including glucotoxicity, lipotoxicity, and other associated secondary adverse effects. TFs exert effects to lower blood glucose and lipids levels, partly by regulating digestive enzyme activities, activation of OATP-MCT pathway and increasing secretion of incretins such as GIP. By the Ca2+-CaMKK ꞵ-AMPK and PI3K-AKT pathway, TFs promote glucose utilization and inhibit endogenous glucose production. Along with the regulation of energy metabolism by AMPK-SIRT1 pathway, TFs enhance fatty acids oxidation and reduce de novo lipogenesis. As such, the administration of TFs holds significant promise for both the prevention and amelioration of diabetes mellitus.

Diet and Management of Diarrhea

Diet plays an important role in human health and disease. Of all human diseases, diarrheal illnesses bring diet into sharp focus as it has a direct causal and therapeutic relationship. With the advent and widespread use of next generation sequencing, significant advances have been made in unraveling the etiologies of congenital diarrheas and enteropathies, some of which are eminently treatable with dietary modification. Early institution of appropriate dietary therapy is lifesaving in congenital osmotic diarrheas. Chronic diarrhea in older children and adolescents often have an underlying dietary basis, depending on the etiology. Identification and exclusion of the offending food in the diet results in dramatic improvement in symptoms. It is equally important to be prudent and cautious in the use of exclusion diets in management of chronic diarrhea as it is associated with micronutrient deficiencies, needless escalation of cost and enable maladaptive food intake behaviors. In this review, authors discuss etiology specific dietary management of diarrhea in children with emphasis on congenital diarrheas and enteropathies.

Transcellular Barriers to Glucose Delivery in the Body

Glucose is the universal fuel of most mammalian cells, and it is largely replenished through dietary intake. Glucose availability to tissues is paramount for the maintenance of homeostatic energetics and, hence, supply should match demand by the consuming organs. In its journey through the body, glucose encounters cellular barriers for transit at the levels of the absorbing intestinal epithelial wall, the renal epithelium mediating glucose reabsorption, and the tight capillary endothelia (especially in the brain). Glucose transiting through these cellular barriers must escape degradation to ensure optimal glucose delivery to the bloodstream or tissues. The liver, which stores glycogen and generates glucose de novo, must similarly be able to release it intact to the circulation. We present the most up-to-date knowledge on glucose handling by the gut, liver, brain endothelium, and kidney, and discuss underlying molecular mechanisms and open questions. Diseases associated with defects in glucose delivery and homeostasis are also briefly addressed. We propose that the universal problem of sparing glucose from catabolism in favor of translocation across the barriers posed by epithelia and endothelia is resolved through common mechanisms involving glucose transfer to the endoplasmic reticulum, from where glucose exits the cells via unconventional cellular mechanisms.

Novel Mutation in the SLC5A1 Gene Causing Glucose-Galactose Malabsorption: First Confirmed Case From Central America

Congenital glucose-galactose malabsorption is a rare cause of life-threatening diet-induced diarrhea in infants. Mutations in the SLC5A1 gene, which encodes for the sodium-dependent glucose transporter, result in large-volume diarrhea due to aberrant glucose and galactose transport across the intestinal brush border. The diagnosis can be made clinically based on the presence of diarrhea soon after birth, evidence of carbohydrate malabsorption in the stool, and resolution of diarrhea with dietary elimination of glucose and galactose. Genetic testing can confirm the diagnosis. Here we report the first confirmed case of glucose-galactose malabsorption in an infant from Central America due to a novel mutation in the SLC5A1 gene. The patient began growing and thriving after being diagnosed and with the correct dietary interventions.

Identification of novel small molecule inhibitors for solute carrier SGLT1; a computational exploration

Diabetes results in substantial disabilities, diminished quality of life, and mortality that imposes a huge economic burden on societies and governments worldwide. Despite the absence of specific oral therapies at present, there exists an urgent requirement to develop a novel drug for the treatment of diabetes mellitus. The membrane protein sodium glucose co-transporters (SGLT1) present a captivating therapeutic target for diabetes, given its pivotal role in facilitating glucose absorption in the small intestine, offering immense promise for potential therapeutic intervention. In this connection, the present study is aimed at identifying potential inhibitors of SGLT1 from a small molecule database, including compounds from both natural as well as synthetic origins. A comprehensive approach was employed, by integrating homology modeling, ligand-based pharmacophore modeling, virtual screening, and molecular docking simulation. The process resulted in the identification of 16 new compounds, featuring similar attributes as observed for the documented actives. In a systematic screening procedure, five potential virtual hits were selected for simulation studies followed by subsequent binding free energy calculations, providing deeper insight into the time-dependent behavior of protein-ligand complexes in a dynamic state. In conclusion, our findings demonstrated that the identified compounds, particularly compounds 81 and 91, exhibit enhanced stability and favorable binding affinities with the target protein, marking them promising candidates for further investigations.Communicated by Ramaswamy H. Sarma.

SGLT1: A Potential Drug Target for Cardiovascular Disease

SGLT1 and SGLT2 are the two main members of the sodium-glucose cotransporters (SGLTs), which are mainly responsible for glucose reabsorption in the body. In recent years, many large clinical trials have shown that SGLT2 inhibitors have cardiovascular protection for diabetic and non-diabetic patients independent of lowering blood glucose. However, SGLT2 was barely detected in the hearts of humans and animals, while SGLT1 was highly expressed in myocardium. As SGLT2 inhibitors also have a moderate inhibitory effect on SGLT1, the cardiovascular protection of SGLT2 inhibitors may be due to SGLT1 inhibition. SGLT1 expression is associated with pathological processes such as cardiac oxidative stress, inflammation, fibrosis, and cell apoptosis, as well as mitochondrial dysfunction. The purpose of this review is to summarize the protective effects of SGLT1 inhibition on hearts in various cell types, including cardiomyocytes, endothelial cells, and fibroblasts in preclinical studies, and to highlight the underlying molecular mechanisms of protection against cardiovascular diseases. Selective SGLT1 inhibitors could be considered a class of drugs for cardiac-specific therapy in the future.

SLC5A1 Variants in Turkish Patients with Congenital Glucose-Galactose Malabsorption

Congenital glucose-galactose malabsorption is a rare autosomal recessive disorder caused by mutations in SLC5A1 encoding the apical sodium/glucose cotransporter SGLT1. We present clinical and molecular data from eleven affected individuals with congenital glucose-galactose malabsorption from four unrelated, consanguineous Turkish families. Early recognition and timely management by eliminating glucose and galactose from the diet are fundamental for affected individuals to survive and develop normally. We identified novel SLC5A1 missense variants, p.Gly43Arg and p.Ala92Val, which were linked to disease in two families. Stable expression in CaCo-2 cells showed that the p.Ala92Val variant did not reach the plasma membrane, but was retained in the endoplasmic reticulum. The p.Gly43Arg variant, however, displayed processing and plasma membrane localization comparable to wild-type SGLT1. Glycine-43 displays nearly invariant conservation in the relevant structural family of cotransporters and exchangers, and localizes to SGLT1 transmembrane domain TM0. p.Gly43Arg represents the first disease-associated variant in TM0; however, the role of TM0 in the SGLT1 function has not been established. In summary, we are expanding the mutational spectrum of this rare disorder.

Comparison of the effects of empagliflozin and sotagliflozin on a zebrafish model of diabetic heart failure with reduced ejection fraction

The sodium-glucose cotransporter 2 (SGLT2) inhibitor empagliflozin (EMPA) and dual SGLT1/2 inhibitor sotagliflozin (SOTA) are emerging as heart failure (HF) medications in addition to having glucose-lowering effects in diabetes mellitus (DM). However, the precise mechanism underlying this cardioprotective effect has not yet been elucidated. Here, we evaluated the effects of EMPA and SOTA in a zebrafish model of DM combined with HF with reduced ejection fraction (DM-HFrEF). To compare the effects of the two drugs, survival, locomotion, and myocardial contractile function were evaluated. The structural binding and modulating effects of the two medications on sodium-hydrogen exchanger 1 (NHE1) were evaluated in silico and in vitro. DM-HFrEF zebrafish showed impaired cardiac contractility and decreased locomotion and survival, all of which were improved by 0.2-5 μM EMPA or SOTA treatment. However, the 25 μM SOTA treatment group had worse survival rates and less locomotion preservation than the EMPA treatment group at the same concentration, and pericardial edema and an uninflated swim bladder were observed. SOTA, EMPA and cariporide (CARI) showed similar structural binding affinities to NHE1 in a molecular docking analysis and drug response affinity target stability assay. In addition, EMPA, SOTA, and CARI effectively reduced intracellular Na+ and Ca2+ changes through the inhibition of NHE1 activity. These findings suggest that both EMPA and SOTA exert cardioprotective effects in the DM-HFrEF zebrafish model by inhibiting NHE1 activity. In addition, despite the similar cardioprotective effects of the two drugs, SOTA may be less effective than EMPA at high concentrations.

Fructose Metabolism and Its Effect on Glucose-Galactose Malabsorption Patients: A Literature Review

Glucose-galactose malabsorption is a rare inherited autosomal recessive genetic defect. A mutation in the glucose sodium-dependent transporter-1 gene will alter the transportation and absorption of glucose and galactose in the intestine. The defect in the SGLT-1 leads to unabsorbed galactose, glucose, and sodium, which stay in the intestine, leading to dehydration and hyperosmotic diarrhea. Often, glucose-galactose malabsorption patients are highly dependent on fructose, their primary source of carbohydrates. This study aims to investigate all published studies on congenital glucose-galactose malabsorption and fructose malabsorption. One hundred published studies were assessed for eligibility in this study, and thirteen studies were identified and reviewed. Studies showed that high fructose consumption has many health effects and could generate life-threatening complications. None of the published studies included in this review discussed or specified the side effects of fructose consumption as a primary source of carbohydrates in congenital glucose-galactose malabsorption patients.

Mechanisms of SGLT2 Inhibitors in Heart Failure and Their Clinical Value

ABSTRACT

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are widely used to treat diabetes mellitus. Abundant evidence has shown that SGLT2 inhibitors can reduce hospitalization for heart failure (HF) in patients with or without diabetes. An increasing number of studies are being conducted on the mechanisms of action of SGLT2 inhibitors in HF. Our review summarizes a series of clinical trials on the cardioprotective effects of SGLT2 inhibitors in the treatment of HF. We have summarized several classical SGLT2 inhibitors in cardioprotection research, including empagliflozin, dapagliflozin, canagliflozin, ertugliflozin, and sotagliflozin. In addition, we provided a brief overview of the safety and benefits of SGLT2 inhibitors. Finally, we focused on the mechanisms of SGLT2 inhibitors in the treatment of HF, including ion-exchange regulation, volume regulation, ventricular remodeling, and cardiac energy metabolism. Exploring the mechanisms of SGLT2 inhibitors has provided insight into repurposing these diabetic drugs for the treatment of HF.

SGLT-2 as a potential target in pancreatic cancer: the preliminary clue from The Cancer Genome Atlas data

BACKGROUND

Sodium-glucose co-transporters-2 (SGLT-2) has been reported as overexpressed in tumors including pancreatic cancer (PC). The aim of this study was to investigate the clinicopathological and prognostic significance, as well as the potential role of SGLT-2 in PC development and progression.

METHODS

The expression of SGLT-2 was assessed using The Cancer Genome Atlas (TCGA) PC dataset (179 cases). The overall survival (OS) and disease-free survival (DFS) of PC patients with high and low SLC5A2 expression were compared using the online database Gene Expression Profiling Interactive Analysis (GEPIA). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed using The Database for Annotation Visualization and Integrated Discovery (DAVID) online tool. The genetic correlations of SLC5A2 genes in different subtypes of PC were analyzed by using cBioPortal and LinkedOmics online databases.

RESULTS

No relationship between SGLT-2 expression and PC risk factors, tumor location, histology grade, or tumor-node-metastasis (TNM) stage was identified. Further, SGLT-2 could not be used as prognosis predictor. The KEGG analyses demonstrated that high SGLT-2 expression is correlated with activation of pathways related with chemical carcinogenesis, energy metabolism and drug metabolism, and the suppression of nucleotide excision repair, messenger RNA (mRNA) surveillance, and cell cycle regulation. Specifically, high SGLT-2 level also coexisted with upregulation of gene symbols for pancreatic progenitor subtype for PC.

CONCLUSIONS

There is potential for SGLT-2 as a potential target for PC treatment, and SGLT-2 inhibitors should be further evaluated as a novel therapy in PC.

Importance of Early Genetic Sequencing in Neonates Admitted to NICU with Recurrent Hypernatremia: Results of a Prospective Cohort Study

OBJECTIVES

The genetic characteristics in neonates admitted to the NICU with recurrent hypernatremia remained unknown. We aimed to implement early genetic sequencing to identify possible genetic etiologies, optimize the treatment, and improve the outcome.

METHODS

We prospectively performed exome sequencing or targeted panel sequencing on neonates diagnosed with recurrent hypernatremia (plasma sodium ≥150 mEq/L, ≥2 episodes) from January 1, 2016, to June 30, 2020.

RESULTS

Among 22,375 neonates admitted to the NICU, approximately 0.33% (73/22,375) developed hypernatremia. The incidence of hypernatremia >14 days and ≤14 days was 0.03% and 0.3%, respectively. Among 38 neonates who had ≥2 hypernatremia episodes, parents of 28 patients consented for sequencing. Genetic diagnosis was achieved in 25% neonates (7/28). Precision medicine treatment was performed in 85.7% (6/7) of the patients, including hydrochlorothiazide and indomethacin for 57.1% (4/7) with arginine vasopressin receptor 2 (AVPR2) deficiency-associated congenital nephrogenic diabetes insipidus; a special diet of fructose formula for 1 patient with solute carrier family 5 member 1 deficiency-associated congenital glucose-galactose malabsorption (1/7, 14.3%); and kallikrein-inhibiting ointment for 1 patient with serine protease inhibitor of Kazal-type 5 deficiency-associated Netherton syndrome (1/7, 14.3%). Only hypernatremia onset age (adjusted odds ratio 1.32 [1.01-1.72], p = 0.040) independently predicted the underlying genetic etiology. The risk of a genetic etiology of hypernatremia was 9.0 times higher for neonates with a hypernatremia onset age ≥17.5 days (95% confidence interval, 1.1-73.2; p = 0.038).

CONCLUSIONS

Single-gene disorders are common in neonates with recurrent hypernatremia, and >50% of cases are caused by AVPR2 deficiency-associated congenital nephrogenic diabetes insipidus. Early genetic testing can aid the diagnosis of unexplained recurrent neonatal hypernatremia and improve therapy and outcome.

Clinical features of pediatric renal glucosuria cases due to SLC5A2 gene variants

BACKGROUND

Familial renal glycosuria (FRG) is a rare renal tubular disorder characterized by a variable loss of glucose in the urine despite normal blood glucose levels, which is seen in a condition in which other tubular functions are preserved. In this study, the molecular and clinical characteristics of pediatric FRG cases due to SLC5A2 gene variants were defined.

METHODS

Demographic features, diagnostic tests, and molecular analyses of patients with a diagnosis of FRG cases due to SLC5A2 gene variants were retrospectively analyzed between 2016 and 2019.

RESULTS

The data of 16 patients who were clinically and genetically diagnosed with FRG in a 4-year period were analyzed. Seven (44%) of the cases were female and 9 (56%) were male. The median age at diagnosis was 6 years old (2 months old to 17 years old). Neuromotor development was found to be appropriate for the age in each case. Systemic blood pressure was evaluated as normal. A homozygous pathogenic variant in the SLC5A2 gene was detected in 14 patients in the genetic examination. A heterozygous variant was detected in one patient. In the other patient, two different heterozygous pathological variants were found in the SLC5A2 gene.

CONCLUSIONS

It was revealed that growth and development were normal in children with glucosuria due to variations in the SCL5A2 gene. Renal function tests and urinary amino acid excretion were also within normal values. In our case series, the most common genetic variation in the SCL5A2 gene was the A219T (c.655G>A) variant.

Structure and mechanism of the SGLT family of glucose transporters

Glucose is a primary energy source in living cells. The discovery in 1960s that a sodium gradient powers the active uptake of glucose in the intestine¹ heralded the concept of a secondary active transporter that can catalyse the movement of a substrate against an electrochemical gradient by harnessing energy from another coupled substrate. Subsequently, coupled Na⁺/glucose transport was found to be mediated by sodium-glucose cotransporters^2,3 (SGLTs). SGLTs are responsible for active glucose and galactose absorption in the intestine and for glucose reabsorption in the kidney⁴, and are targeted by multiple drugs to treat diabetes⁵. Several members within the SGLT family transport key metabolites other than glucose². Here we report cryo-electron microscopy structures of the prototypic human SGLT1 and a related monocarboxylate transporter SMCT1 from the same family. The structures, together with molecular dynamics simulations and functional studies, define the architecture of SGLTs, uncover the mechanism of substrate binding and selectivity, and shed light on water permeability of SGLT1. These results provide insights into the multifaceted functions of SGLTs.

Sodium/glucose cotransporter 2 and renoprotection: From the perspective of energy regulation and water conservation

Sodium/glucose cotransporter 2 (SGLT2) is a renal low-affinity high-capacity sodium/glucose cotransporter expressed in the apical membrane of the early segment of proximal tubules. SGLT2 reabsorbs filtered glucose in the kidney, and its inhibitors represent a new class of oral medications used for type 2 diabetes mellitus, which act by increasing glucose and sodium excretion in urine, thereby reducing blood glucose levels. However, clinical trials showed marked improvement of renal outcomes, even in nondiabetic kidney diseases, although the underlying mechanism of this renoprotective effect is unclear. We showed that long-term excretion of salt by the kidneys, which predisposes to osmotic diuresis and water loss, induces a systemic body response for water conservation. The energy-intensive nature of water conservation leads to a reprioritization of systemic body energy metabolism. According to current data, use of SGLT2 inhibitors may result in similar reprioritization of energy metabolism to prevent dehydration. In this review article, we discuss the beneficial effects of SGLT2 inhibition from the perspective of energy metabolism and water conservation.

The Molecular Basis of Glucose Galactose Malabsorption in a Large Swedish Pedigree

Glucose-galactose malabsorption (GGM) is due to mutations in the gene coding for the intestinal sodium glucose cotransporter SGLT1 (SLC5A1). Here we identify the rare variant Gln457Arg (Q457R) in a large pedigree of patients in the Västerbotten County in Northern Sweden with the clinical phenotype of GGM. The functional effect of the Q457R mutation was determined in protein expressed in Xenopus laevis oocytes using biophysical and biochemical methods. The mutant failed to transport the specific SGLT1 sugar analog α-methyl-D-glucopyranoside (αMDG). Q457R SGLT1 was synthesized in amounts comparable to the wild-type (WT) transporter. SGLT1 charge measurements and freeze-fracture electron microscopy demonstrated that the mutant protein was inserted into the plasma membrane. Electrophysiological experiments, both steady-state and presteady-state, demonstrated that the mutant bound sugar with an affinity lower than the WT transporter. Together with our previous studies on Q457C and Q457E mutants, we established that the positive charge on Q457R prevented the translocation of sugar from the outward-facing to inward-facing conformation. This is contrary to other GGM cases where missense mutations caused defects in trafficking SGLT1 to the plasma membrane. Thirteen GGM patients are now added to the pedigree traced back to the late 17^th century. The frequency of the Q457R variant in Västerbotten County genomes, 0.0067, is higher than in the general Swedish population, 0.0015, and higher than the general European population, 0.000067. This explains the high number of GGM cases in this region of Sweden.

Moringa oleifera Lam. in Diabetes Mellitus: A Systematic Review and Meta-Analysis

Plant-derived phytochemicals have been interested in as nutraceuticals for preventing the onset and progress of diabetes mellitus and its serious complications in recent years. Moringa oleifera Lam. is used in vegetables and in herbal medicine for its health-promoting properties against various diseases including diabetes mellitus. This study aimed to examine an effect of Moringa oleifera on diabetic hyperglycemia and dyslipidemia by meta-analyzing the current evidence of diabetic rodent models. Peer-reviewed studies written in English from two databases, PubMed and Embase, were searched to 30 April 2021. Studies reporting blood glucose or lipid levels in diabetic rodents with and without receiving extracts of Moringa oleifera were included. Forty-four studies enrolling 349 diabetic rodents treated with extracts of Moringa oleifera and 350 diabetic controls reported blood glucose levels. The pooled effect size was -3.92 (95% CI: -4.65 to -3.19) with a substantial heterogeneity. This effect was likely to be, at least in part, modified by the type of diabetic models. Moreover, diabetic hypertriglyceridemia and hypercholesterolemia were also significantly improved in diabetic rodent models treated with Moringa oleifera.

Pharmacokinetics, metabolism, and excretion of licogliflozin, a dual inhibitor of SGLT1/2, in rats, dogs, and humans

Absorption, metabolism, and excretion (AME) of licogliflozin, a sodium-glucose co-transporters (SGLTs) 1 and 2 inhibitor, were studied in male rats, dogs, and healthy male volunteers and reported.Oral absorption of licogliflozin was rapid (t_max < 1 h) with absorption estimated at 87%, 100% and 77% in rats, dogs and humans, respectively.Excretion of licogliflozin-related radioactivity was rapid and nearly complete following oral administration with total radioactivity recovery ranging from 73% in dogs, 92.5% in humans, to 100% in rats. Dose-related radioactivity was excreted in both urine and faeces with urinary excretion playing a slightly more important role in humans (∼56%) than in animal species (∼19-41%).Elimination of licogliflozin was predominantly via metabolism with the majority of the radioactivity dose (∼54-74%) excreted as metabolites across species.The principal biotransformation pathways involved direct glucuronidation and oxidation across all species. In humans, direct glucuronidation to M17 and M27 was the major pathway observed, accounting for ∼38% of the dose in excreta while oxidative metabolism also contributed to >29% of the dose in excreta. Oxidative pathways were predominant in animal species.

Long-Term Dietary Changes in Subjects with Glucose Galactose Malabsorption Secondary to Biallelic Mutations of SLC5A1

BACKGROUND

Glucose galactose malabsorption (GGM) is a congenital diarrheal disorder of intestinal Na+/glucose cotransport (SGLT1/SLC5A1). The required glucose and galactose-restricted diet has been well described in infancy, but long-term nutrition follow-up is limited.

AIM

To perform a comprehensive nutritional assessment on a cohort of patients with GGM to gain insights into the consumption patterns within the population.

METHODS

A cross-sectional study examining dietary intake of a GGM cohort using prospective food records. The calories and nutrients of all foods, beverages, and condiments were analyzed with descriptive statistics and compared to intake patterns of age- and sex-matched NHANES groups.

RESULTS

The six patients were 0.7-26 years old. Whole foods and vegetable fats were major parts of the diet, while dairy and added sweeteners were restricted. Compared to typical US intakes, mean macronutrient distribution was 88th percentile from fat, 18th percentile from carbohydrates, and 78th percentile from protein. Fructose consumption, as a proportion of total sugar intake, decreased with age, from 86.1 to 50.4%. Meanwhile, glucose consumption increased with age, from 13.8 to 48.6% of sugar intake. However, the actual amount of glucose consumed remained low, equivalent to 4th percentile of US consumption level. Galactose intake was marginal throughout life.

CONCLUSIONS

A GGM diet is a high-fat and high-protein/low-carbohydrate diet that is rich in fruits and vegetables but limited in dairy and added sugar. Relatively less fructose but more glucose is incorporated into the diet with age. Future studies should investigate the effects of the GGM diet on gut microbiome and long-term health.

A comprehensive overview of substrate specificity of glycoside hydrolases and transporters in the small intestine : "A gut feeling"

The human body is able to process and transport a complex variety of carbohydrates, unlocking their nutritional value as energy source or as important building block. The endogenous glycosyl hydrolases (glycosidases) and glycosyl transporter proteins located in the enterocytes of the small intestine play a crucial role in this process and digest and/or transport nutritional sugars based on their structural features. It is for these reasons that glycosidases and glycosyl transporters are interesting therapeutic targets to combat sugar related diseases (such as diabetes) or to improve drug delivery. In this review we provide a detailed overview focused on the molecular structure of the substrates involved as a solid base to start from and to fuel research in the area of therapeutics and diagnostics.

Role of intestinal glucose absorption in glucose tolerance

Intestinal glucose absorption is integral to postprandial glucose homeostasis. Glucose absorption is dependent on a number of factors, including the exposure of carbohydrate to the mucosa of the upper gastrointestinal tract (determined particularly by the rates of gastric emptying and small intestinal transit), the digestion of complex carbohydrate into monosaccharides, and glucose sensing and transport by the intestinal mucosa. The absorption of glucose in the small intestine is not only a determinant of the appearance of exogenous glucose in the peripheral circulation, but is also coupled to the release of gastrointestinal hormones that in turn influence postprandial glucose metabolism through modulating gastrointestinal motor function, insulin and glucagon secretion, and subsequent energy intake. This review describes the physiology and pathophysiology of intestinal glucose absorption in health and type 2 diabetes, including its relevance to glucose tolerance and the management of postprandial hyperglycaemia.

Literature review on congenital glucose-galactose malabsorption from 2001 to 2019

AIM

Congenital glucose-galactose malabsorption (CGGM) is a rare disease characterised by severe diarrhoea, dehydration and weight loss. To better understand CGGM, we investigated all the case reports and series of CGGM from 2001 to 2019.

METHODS

A review of reports of CGGM published from 2001 to 2019 was undertaken, using PubMed, Ovid Medline, Springer, Wanfang Database, CBMD database and CKNI database. The clinical features, diagnosis, treatment and prognosis of CGGM in these reports were obtained and analysed.

RESULTS

We reviewed 107 cases for this study. Out of 55 cases from Saudi Arabia and Turkey, 43 cases (78.2%) were from consanguineous marriage. Forty-nine cases (73.1%) were infants. Dehydration, diarrhoea and weight loss occurred in almost all cases. Half of the cases presented hypernatremia and abdominal distension. Vomiting, polyuria/haematuria and fever were reported in 11, 7 and 3 cases, respectively. Twenty cases (18.7%) showed hypercalcaemia or nephrolithiasis. Stool pH was tested in 43 cases (40.2%). Fifty-five cases (51.4%) were diagnosed for more than 1 month after the onset of symptoms. Two cases (1.9%) died, one needed amputation, and the other 104 cases (97.2%) recovered with fructose formula. Seventy-three cases (68.2%) underwent gene testing, 30 SLC5A1 gene mutations were detected, with 23 cases homozygous, and seven heterozygous mutation.

CONCLUSION

The clinical characteristics of CGGM are nonspecific, and the diagnosis method is not conventionally applied. Fasting and gene testing are the two most important diagnostic methods. The best treatment of CGGM is supplementation with fructose-based formula.

SGLT2 inhibitors, an accomplished development in field of medicinal chemistry: an extensive review

Diabetes is a chronic progressive metabolic disease caused by insulin deficiency or insulin resistance. In spite of the availability of several antihyperglycaemics, there is a need for the development of safer antidiabetic drugs due to their undesirable effects. Sodium-glucose cotransporter-2 inhibitors are a class of antidiabetics, which hinder the reabsorption of glucose in the kidneys, causing excretion of glucose via urine. Sodium-glucose cotransporter-2 inhibitors are a well-tolerated class with no significant adverse effects and are found to be favorable in certain conditions, which may be rudimentary to cardiovascular and renal diseases. The current advancements in their design and development, their mechanism of action, structure–activity relationship, synthesis and in silico development along with their auxiliary roles have been extensively reviewed.

Evaluation of dapagliflozin in the treatment of heart failure

The European Society of Cardiology recently addressed the use of SGLT2 inhibitor use in the treatment of heart failure (HF). Dapagliflozin is a SGLT2 inhibitor recently approved by the US FDA for treatment of patients with HF with a reduced ejection fraction with a New York Heart Association classification of II-IV. Dapagliflozin significantly decreases the risk of worsening HF or death from cardiovascular cause compared with placebo and this risk does not differ based on the presence or absence of Type 2 diabetes. This paper aims to summarize the chemistry, pharmacodynamics and pharmacokinetics of dapagliflozin; and evaluates the clinical efficacy of dapagliflozin in the treatment of HF.

Fucoidan from Ascophyllum nodosum Suppresses Postprandial Hyperglycemia by Inhibiting Na+/Glucose Cotransporter 1 Activity

We previously demonstrated that fucoidan with a type II structure inhibited postprandial hyperglycemia by suppressing glucose uptake, but the mechanism remains elusive. Here, we aimed to assess whether the effect of glucose absorption inhibition was related to the basic structure of fucoidans and preliminarily clarified the underlying mechanism. Fucoidans with type II structure and type I structure were prepared from Ascophyllumnodosum (AnF) or Laminariajaponica (LjF) and Kjellmaniellacrassifolia (KcF), respectively. The effects of various fucoidans on suppressing postprandial hyperglycemia were investigated using in vitro (Caco-2 monolayer model), semi-in vivo (everted gut sac model), and in vivo (oral glucose tolerance test, OGTT) assays. The results showed that only AnF with a type II structure, but not LjF or KcF with type I structure, could inhibit the glucose transport in the Caco-2 monolayer and everted gut sac models. A similar result was seen in the OGTT of Kunming mice and leptin receptor-deficient (db/db) mice, where only AnF could effectively inhibit glucose transport into the bloodstream. Furthermore, AnF (400 mg/kg/d) treatment decreased the fasting blood glucose, HbA1c, and fasting insulin levels, while increasing the serum glucagon-like peptide-1 (GLP-1) level in obese leptin receptor-deficient (db/db) mice. Furthermore, surface plasmon resonance (SPR) analysis revealed the specific binding of AnF to Na+/glucose cotransporter 1 (SGLT1), which indicated the effect of AnF on postprandial hyperglycemia could be due to its suppression on SGLT1 activity. Taken together, this study suggests that AnF with a type II structure can be a promising candidate for hyperglycemia treatment.

Glucose transporters in the small intestine in health and disease

Absorption of monosaccharides is mainly mediated by Na+-D-glucose cotransporter SGLT1 and the facititative transporters GLUT2 and GLUT5. SGLT1 and GLUT2 are relevant for absorption of D-glucose and D-galactose while GLUT5 is relevant for D-fructose absorption. SGLT1 and GLUT5 are constantly localized in the brush border membrane (BBM) of enterocytes, whereas GLUT2 is localized in the basolateral membrane (BLM) or the BBM plus BLM at low and high luminal D-glucose concentrations, respectively. At high luminal D-glucose, the abundance SGLT1 in the BBM is increased. Hence, D-glucose absorption at low luminal glucose is mediated via SGLT1 in the BBM and GLUT2 in the BLM whereas high-capacity D-glucose absorption at high luminal glucose is mediated by SGLT1 plus GLUT2 in the BBM and GLUT2 in the BLM. The review describes functions and regulations of SGLT1, GLUT2, and GLUT5 in the small intestine including diurnal variations and carbohydrate-dependent regulations. Also, the roles of SGLT1 and GLUT2 for secretion of enterohormones are discussed. Furthermore, diseases are described that are caused by malfunctions of small intestinal monosaccharide transporters, such as glucose-galactose malabsorption, Fanconi syndrome, and fructose intolerance. Moreover, it is reported how diabetes, small intestinal inflammation, parental nutrition, bariatric surgery, and metformin treatment affect expression of monosaccharide transporters in the small intestine. Finally, food components that decrease D-glucose absorption and drugs in development that inhibit or downregulate SGLT1 in the small intestine are compiled. Models for regulations and combined functions of glucose transporters, and for interplay between D-fructose transport and metabolism, are discussed.

Sodium-coupled glucose transport, the SLC5 family, and therapeutically relevant inhibitors: from molecular discovery to clinical application

Sodium glucose transporters (SGLTs) belong to the mammalian solute carrier family SLC5. This family includes 12 different members in human that mediate the transport of sugars, vitamins, amino acids, or smaller organic ions such as choline. The SLC5 family belongs to the sodium symporter family (SSS), which encompasses transporters from all kingdoms of life. It furthermore shares similarity to the structural fold of the APC (amino acid-polyamine-organocation) transporter family. Three decades after the first molecular identification of the intestinal Na+-glucose cotransporter SGLT1 by expression cloning, many new discoveries have evolved, from mechanistic analysis to molecular genetics, structural biology, drug discovery, and clinical applications. All of these advances have greatly influenced physiology and medicine. While SGLT1 is essential for fast absorption of glucose and galactose in the intestine, the expression of SGLT2 is largely confined to the early part of the kidney proximal tubules, where it reabsorbs the bulk part of filtered glucose. SGLT2 has been successfully exploited by the pharmaceutical industry to develop effective new drugs for the treatment of diabetic patients. These SGLT2 inhibitors, termed gliflozins, also exhibit favorable nephroprotective effects and likely also cardioprotective effects. In addition, given the recent finding that SGLT2 is also expressed in tumors of pancreas and prostate and in glioblastoma, this opens the door to potential new therapeutic strategies for cancer treatment by specifically targeting SGLT2. Likewise, further discoveries related to the functional association of other SGLTs of the SLC5 family to human pathologies will open the door to potential new therapeutic strategies. We furthermore hope that the herein summarized information about the physiological roles of SGLTs and the therapeutic benefits of the gliflozins will be useful for our readers to better understand the molecular basis of the beneficial effects of these inhibitors, also in the context of the tubuloglomerular feedback (TGF), and the renin-angiotensin system (RAS). The detailed mechanisms underlying the clinical benefits of SGLT2 inhibition by gliflozins still warrant further investigation that may serve as a basis for future drug development.

Dose-dependent reduction in body weight with LIK066 (licogliflozin) treatment in Japanese patients with obesity

AIMS

LIK066 (licogliflozin) is a dual sodium glucose co-transporter 1/2 inhibitor with potential benefits in weight loss. This study evaluated the efficacy, tolerability and safety of licogliflozin in Japanese adults with obesity.

MATERIALS AND METHODS

This study was a randomized, double-blind, placebo-controlled, dose-finding study to evaluate the effect of licogliflozin (2.5, 10, 25 and 50 mg once daily) in 126 Japanese patients with obesity. The primary objective was to examine the dose-response relationship of licogliflozin treatment in body weight reduction relative to placebo at 12 weeks. The secondary objectives included assessment of responder rates, change in parameters related to complications, visceral and subcutaneous fat area, and safety during 12 weeks of treatment.

RESULTS

The placebo-subtracted least square mean percentage change in body weight from baseline at week 12 was -1.99 (95% confidence interval -2.92, -0.21), -3.00 (-4.15, -1.70), -3.54 (-4.54, -2.26) and - 3.91% (-5.01, -2.77) in licogliflozin 2.5, 10, 25 and 50 mg once-daily dose groups, respectively. The proportion of responders with ≥3% reduction in body weight in the licogliflozin 2.5, 10, 25 and 50 mg once-daily dose groups were 15.8%, 55.6%, 50.0% and 56.7%, respectively, versus placebo [7.1%; P ≤0.002 for all except the 2.5 mg once-daily group (P = 0.39)]. Dose-dependent reductions were observed significantly in haemoglobin A1c, uric acid, fasting plasma glucose and potentially in the waist circumference, diastolic blood pressure and visceral fat area.

CONCLUSION

Dual inhibition of SGLT1/2 with licogliflozin treatment induced a dose-dependent reduction in body weight in Japanese patients with obesity. Treatment with licogliflozin was safe and well tolerated in this study. The study is registered with ClinicalTrials.gov (NCT03320941).

Changes in Myocardial Metabolism Preceding Sudden Cardiac Death

Heart disease is widely recognized as a major cause of death worldwide and is the leading cause of mortality in the United States. Centuries of research have focused on defining mechanistic alterations that drive cardiac pathogenesis, yet sudden cardiac death (SCD) remains a common unpredictable event that claims lives in every age group. The heart supplies blood to all tissues while maintaining a constant electrical and hormonal feedback communication with other parts of the body. As such, recent research has focused on understanding how myocardial electrical and structural properties are altered by cardiac metabolism and the various signaling pathways associated with it. The importance of cardiac metabolism in maintaining myocardial function, or lack thereof, is exemplified by shifts in cardiac substrate preference during normal development and various pathological conditions. For instance, a shift from fatty acid (FA) oxidation to oxygen-sparing glycolytic energy production has been reported in many types of cardiac pathologies. Compounded by an uncoupling of glycolysis and glucose oxidation this leads to accumulation of undesirable levels of intermediate metabolites. The resulting accumulation of intermediary metabolites impacts cardiac mitochondrial function and dysregulates metabolic pathways through several mechanisms, which will be reviewed here. Importantly, reversal of metabolic maladaptation has been shown to elicit positive therapeutic effects, limiting cardiac remodeling and at least partially restoring contractile efficiency. Therein, the underlying metabolic adaptations in an array of pathological conditions as well as recently discovered downstream effects of various substrate utilization provide guidance for future therapeutic targeting. Here, we will review recent data on alterations in substrate utilization in the healthy and diseased heart, metabolic pathways governing cardiac pathogenesis, mitochondrial function in the diseased myocardium, and potential metabolism-based therapeutic interventions in disease.

Cardiac sodium-dependent glucose cotransporter 1 is a novel mediator of ischaemia/reperfusion injury

AIMS

We previously reported that sodium-dependent glucose cotransporter 1 (SGLT1) is highly expressed in cardiomyocytes and is further up-regulated in ischaemia. This study aimed to determine the mechanisms by which SGLT1 contributes to ischaemia/reperfusion (I/R) injury.

METHODS AND RESULTS

Mice with cardiomyocyte-specific knockdown of SGLT1 (TGSGLT1-DOWN) and wild-type controls were studied. In vivo, the left anterior descending coronary artery was ligated for 30 min and reperfused for 48 h. Ex vivo, isolated perfused hearts were exposed to 20 min no-flow and up to 2 h reperfusion. In vitro, HL-1 cells and isolated adult murine ventricular cardiomyocytes were exposed to 1 h hypoxia and 24 h reoxygenation (H/R). We found that TGSGLT1-DOWN hearts were protected from I/R injury in vivo and ex vivo, with decreased infarct size, necrosis, dysfunction, and oxidative stress. 5'-AMP-activated protein kinase (AMPK) activation increased SGLT1 expression, which was abolished by extracellular signal-related kinase (ERK) inhibition. Co-immunoprecipitation studies showed that ERK, but not AMPK, interacts directly with SGLT1. AMPK activation increased binding of the hepatocyte nuclear factor 1 and specificity protein 1 transcription factors to the SGLT1 gene, and HuR to SGLT1 mRNA. In cells, up-regulation of SGLT1 during H/R was abrogated by AMPK inhibition. Co-immunoprecipitation studies showed that SGLT1 interacts with epidermal growth factor receptor (EGFR), and EGFR interacts with protein kinase C (PKC). SGLT1 overexpression activated PKC and NADPH oxidase 2 (Nox2), which was attenuated by PKC inhibition, EGFR inhibition, and/or disruption of the interaction between EGFR and SGLT1.

CONCLUSION

During ischaemia, AMPK up-regulates SGLT1 through ERK, and SGLT1 interacts with EGFR, which in turn increases PKC and Nox2 activity and oxidative stress. SGLT1 may represent a novel therapeutic target for mitigating I/R injury.

AP1S1 missense mutations cause a congenital enteropathy via an epithelial barrier defect

Congenital diarrheal disorders (CDD) comprise > 50 monogenic entities featuring chronic diarrhea of early-onset, including defects in nutrient and electrolyte absorption, enterocyte polarization, enteroendocrine cell differentiation, and epithelial integrity. Diarrhea is also a predominant symptom in many immunodeficiencies, congenital disorders of glycosylation, and in some defects of the vesicular sorting and transporting machinery. We set out to identify the etiology of an intractable diarrhea in 2 consanguineous families by whole-exome sequencing, and identified two novel AP1S1 mutations, c.269T>C (p.Leu90Pro) and c.346G>A (p.Glu116Lys). AP1S1 encodes the small subunit of the adaptor protein 1 complex (AP-1), which plays roles in clathrin coat-assembly and trafficking between trans-Golgi network, endosomes and the plasma membrane. An AP1S1 knock-out (KO) of a CaCo2 intestinal cell line was generated to characterize intestinal AP1S1 deficiency as well as identified mutations by stable expression in KO background. Morphology and prototype transporter protein distribution were comparable between parental and KO cells. We observed altered localization of tight-junction proteins ZO-1 and claudin 3, decreased transepithelial electrical resistance and an increased dextran permeability of the CaCo2-AP1S1-KO monolayer. In addition, lumen formation in 3D cultures of these cells was abnormal. Re-expression of wild-type AP1S1 in CaCo2-AP1S1-KO cells reverted these abnormalities, while expression of AP1S1 containing either missense mutation did not. Our data indicate that loss of AP1S1 function causes an intestinal epithelial barrier defect, and that AP1S1 mutations can cause a non-syndromic form of congenital diarrhea, whereas 2 reported truncating AP1S1 mutations caused MEDNIK syndrome, characterized by mental retardation, enteropathy, deafness, neuropathy, ichthyosis, and keratodermia.

Investigation and Management of Stool Frequency and Consistency Associated With SGLT1 Inhibition by Reducing Dietary Carbohydrate: A Randomized Trial

Treatment with licogliflozin, a dual sodium-glucose co-transporter (SGLT)1/2-inhibitor, is associated with increased stool frequency and loose stools, attributed to SGLT1 inhibition. To investigate the effect of carbohydrate content and supplements on licogliflozin-induced stools, a randomized, open-label, two-part (N = 24/part), three-period crossover study was carried out in overweight or obese adults. Significantly higher (P < 0.01) change from baseline in 3-day total number of bowel movements was observed following 3 days of licogliflozin treatment (50 mg q.d.) together with a 50% carbohydrate meal compared with a 25% and 0% carbohydrate meal. The number of stools with Bristol Stool Chart score of 6 or 7 was also significantly lower following a 0% carbohydrate meal. Supplementation with psyllium 6 g or calcium carbonate 1 g had no effect on stool changes following treatment. Licogliflozin was generally safe and well-tolerated. Loose stool associated with licogliflozin treatment and ingestion of meals can be managed by reducing the carbohydrate content of meals taken with licogliflozin.

Effects of the dual sodium-glucose linked transporter inhibitor, licogliflozin vs placebo or empagliflozin in patients with type 2 diabetes and heart failure

Aims

Explore the efficacy, safety and tolerability of the dual sodium–glucose cotransporter (SGLT) 1 and 2 inhibitor, licogliflozin in patients with type‐2 diabetes mellitus (T2DM) and heart failure.

Methods

This multicentre, parallel‐group phase IIA study randomized 125 patients with T2DM and heart failure (New York Heart Association II–IV; plasma N‐terminal pro b‐type natriuretic peptide [NT‐proBNP] >300 pg/mL) to licogliflozin (2.5 mg, 10 mg, 50 mg) taken at bedtime, empagliflozin (25 mg) or placebo (44 patients completed the study). The primary endpoint was change from baseline in NT‐proBNP after 12 weeks. Secondary endpoints included change from baseline in glycated haemoglobin, fasting plasma glucose, weight, blood pressure, fasting lipid profile, high‐sensitivity c‐reactive protein, and safety and tolerability.

Results

Licogliflozin 10 mg for 12 weeks significantly reduced NT‐proBNP vs placebo (Geometric mean ratio 0.56 [95% confidence interval: 0.33, 0.95], P = .033). A trend was observed with 50 mg licogliflozin (0.64 [95% confidence interval: 0.40, 1.03], P = .064), with no difference between licogliflozin and empagliflozin. The largest numerical decreases in glycated haemoglobin were with licogliflozin 50 mg (−0.58 ± 0.34%) and empagliflozin (−0.44 ± 1.18%) vs placebo (−0.04 ± 0.91%). The reduction in body weight was similar with licogliflozin 50 mg (−2.15 ± 2.40 kg) and empagliflozin (−2.25 ± 1.89 kg). A numerical reduction in systolic blood pressure was seen with licogliflozin 50 mg (−9.54 ± 16.88 mmHg) and empagliflozin (−6.98 ± 15.03 mmHg) vs placebo (−2.85 ± 11.97 mmHg). Adverse events (AEs) were mild, including hypotension (6.5%), hypoglycaemia (8.1%) and inadequate diabetes control (1.6%). The incidence of diarrhoea (4.9%) was lower than previously reported.

Conclusion

The reduction in NT‐proBNP with licogliflozin suggests a potential benefit of SGLT1 and 2 inhibition in patients with T2DM and heart failure.

The Race to Bash NASH: Emerging Targets and Drug Development in a Complex Liver Disease

Nonalcoholic steatohepatitis (NASH) is a severe form of nonalcoholic fatty liver disease (NAFLD) characterized by liver steatosis, inflammation, and hepatocellular damage. NASH is a serious condition that can progress to cirrhosis, liver failure, and hepatocellular carcinoma. The association of NASH with obesity, type 2 diabetes mellitus, and dyslipidemia has led to an emerging picture of NASH as the liver manifestation of metabolic syndrome. Although diet and exercise can dramatically improve NASH outcomes, significant lifestyle changes can be challenging to sustain. Pharmaceutical therapies could be an important addition to care, but currently none are approved for NASH. Here, we review the most promising targets for NASH treatment, along with the most advanced therapeutics in development. These include targets involved in metabolism (e.g., sugar, lipid, and cholesterol metabolism), inflammation, and fibrosis. Ultimately, combination therapies addressing multiple aspects of NASH pathogenesis are expected to provide benefit for patients.

Obesity medications in development

Introduction: Obesity is compounded by a neurobiology that is resistant to weight loss. Therefore, the development of pharmacotherapies to address the pathology underlying the dysregulation of energy homeostasis is critical.Areas covered: This review examines selected clinical trial evidence for the pharmacologic treatment of obesity and provides an expert opinion on anti-obesity drug development. The article includes the outcomes of anti-obesity medications that have been evaluated in clinical trials but have not yet received approval from the U.S. Food and Drug Administration. The mechanisms of action of glucagon-like peptide-1 agonists and co-agonists, diabetes medications being investigated for weight loss, and medications acting on the central nervous system as well as peripherally are reviewed. A search was conducted on PubMed using the terms 'Obesity AND Medications' restricted to clinical trials reported in English. Using similar terms, a search was also conducted on ClinicalTrials.gov.Expert opinion: The goal of anti-obesity therapy is finding compounds that are effective and have minimal side effects. Combining medications targeting more than one of the redundant mechanisms driving obesity increases efficacy. However, targeting peripheral mechanisms to overcome the trickle-down effects of centrally acting drugs may be the key to success in treating obesity.

Solute Carrier Transporters as Potential Targets for the Treatment of Metabolic Disease

The solute carrier (SLC) superfamily comprises more than 400 transport proteins mediating the influx and efflux of substances such as ions, nucleotides, and sugars across biological membranes. Over 80 SLC transporters have been linked to human diseases, including obesity and type 2 diabetes (T2D). This observation highlights the importance of SLCs for human (patho)physiology. Yet, only a small number of SLC proteins are validated drug targets. The most recent drug class approved for the treatment of T2D targets sodium-glucose cotransporter 2, product of the SLC5A2 gene. There is great interest in identifying other SLC transporters as potential targets for the treatment of metabolic diseases. Finding better treatments will prove essential in future years, given the enormous personal and socioeconomic burden posed by more than 500 million patients with T2D by 2040 worldwide. In this review, we summarize the evidence for SLC transporters as target structures in metabolic disease. To this end, we identified SLC13A5/sodium-coupled citrate transporter, and recent proof-of-concept studies confirm its therapeutic potential in T2D and nonalcoholic fatty liver disease. Further SLC transporters were linked in multiple genome-wide association studies to T2D or related metabolic disorders. In addition to presenting better-characterized potential therapeutic targets, we discuss the likely unnoticed link between other SLC transporters and metabolic disease. Recognition of their potential may promote research on these proteins for future medical management of human metabolic diseases such as obesity, fatty liver disease, and T2D. SIGNIFICANCE STATEMENT: Given the fact that the prevalence of human metabolic diseases such as obesity and type 2 diabetes has dramatically risen, pharmacological intervention will be a key future approach to managing their burden and reducing mortality. In this review, we present the evidence for solute carrier (SLC) genes associated with human metabolic diseases and discuss the potential of SLC transporters as therapeutic target structures.

Inhibitory Effect of Ocimum gratissimum Leaf Extract on Postprandial Increase of Blood Glucose

The tea of Ocimum gratissimum (OG) leaves has been commonly consumed by people living in Ishigaki Island, Okinawa prefecture, Japan, and is considered to be effective for improving diabetes mellitus. In this study, we aimed to clarify the inhibitory potential of OG leaves extract (OG-ext) on gastrointestinal glucose absorption and to provide theoretical evidence for the anti-hyperglycemic effect of OG-ext. The increase of blood glucose after oral administration of α-starch and glucose in mice was suppressed by co-administration of OG-ext. An in vitro enzymatic assay suggested that amylase and maltase were inhibited weakly by the addition of OG-ext. In Caco-2 cells, a human intestinal epithelial model, the sodium-dependent glucose transporter (SGLT) 1-mediated uptake of fluorescence glucose analog was inhibited significantly by the addition of OG-ext in a concentration-dependent manner. These results indicate that the inhibitory effect on SGLT1 is one of the mechanisms of the anti-hyperglycemic effect of the tea of OG leaves.

Learning Physiology From Inherited Kidney Disorders

The identification of genes causing inherited kidney diseases yielded crucial insights in the molecular basis of disease and improved our understanding of physiological processes that operate in the kidney. Monogenic kidney disorders are caused by mutations in genes coding for a large variety of proteins including receptors, channels and transporters, enzymes, transcription factors, and structural components, operating in specialized cell types that perform highly regulated homeostatic functions. Common variants in some of these genes are also associated with complex traits, as evidenced by genome-wide association studies in the general population. In this review, we discuss how the molecular genetics of inherited disorders affecting different tubular segments of the nephron improved our understanding of various transport processes and of their involvement in homeostasis, while providing novel therapeutic targets. These include inherited disorders causing a dysfunction of the proximal tubule (renal Fanconi syndrome), with emphasis on epithelial differentiation and receptor-mediated endocytosis, or affecting the reabsorption of glucose, the handling of uric acid, and the reabsorption of sodium, calcium, and magnesium along the kidney tubule.