Dapagliflozin modula la secrezione di glucagone con effetto SGLT-2 indipendente in alfa-cellule murine

Gli SGLT2 inibitori riducono il riassorbimento renale di glucosio attraverso un meccanismo completamente insulino-indipendente, consentendo di ottenere, oltre ad un miglioramento del controllo glicemico, anche diversi altri effetti clinicamente rilevanti, come una riduzione del peso corporeo e dei valori pressori. Recentemente, dopo SGLT2 inibizione, è stato descritto un aumento delle concentrazioni plasmatiche di glucagone, ma resta da chiarire se questo effetto dipenda da variazioni metaboliche sistemiche, o sia, invece, dovuto ad un’azione diretta sulle alfa-cellule pancreatiche. Scopo del nostro studio è stato quello di ottenere nuove conoscenze sul meccanismo alla base di questa risposta metabolica: per farlo abbiamo utilizzato una linea alfa-cellulare murina (αTC-1) trattata con Dapagliflozin (Dapa) per diversi intervalli di tempo, ed abbiamo misurato l’espressione dei trasportatori del glucosio, dei mediatori molecolari della secrezione ormonale e il rilascio di glucagone e GLP-1. Abbiamo inoltre studiato l’effetto della somatostatina sulla modulazione di questa risposta ormonale, effetto trascurato negli studi in vivo finora realizzati. I dati sono stati parzialmente confermati anche nelle isole pancreatiche umane e murine. Slc5a2 (gene che codifica per SGLT2) è pressoché indeterminabile nelle cellule αTC-1, nonostante l’utilizzo di tecniche di digital PCR con differenti tipi di sonde. Slc5a1 (che codifica per SGLT1) è costitutivamente espresso sia nelle cellule αTC-1 che nelle isole pancratiche umane e murine, e il trattamento con Dapa ne ha incrementato l’espressione; l’aumentata espressione di questo trasportatore si associa a livelli più elevati di glucagone, preceduti da una aumentata espressione di Pre-proglucagone e Fattore Nucleare Epatocitario 4α. Analizzando i segnali intracellulari che mediano gli effetti di Dapa, è stato possibile evidenziare ridotti livelli di PASK associati ad un aumento di AMPka2. L’espressione di GLUT1 e GLUT2, invece, così come dei regolatori del rilascio di glucagone e dei marcatori alfa-cellulari (Cromogranina A, Paired Box-6, Proconvertasi 1/2, Sinaptofisina) non è influenzata dall'azione del farmaco. Il rilascio di GLP-1 e l’espressione del suo recettore non hanno mostrato differenze significative tra le cellule trattate e quelle non trattate con Dapa, suggerendo che il farmaco influenzi solo il rilascio di glucagone e non l’intero pattern di secrezione alfa-cellulare. La riduzione dei livelli di glucosio ha determinato un leggero aumento dell’espressione di GLUT2, ma non ha influenzato né SGLT1 né GLUT1; l’effetto stimolante di Dapa sulla secrezione del glucagone è rimasto, comunque, immodificato. Infine, il silenziamento genico di Slc5a1 ha consentito di prevenire quasi completamente l’aumento dei livelli di glucagone e l’attivazione del meccanismo molecolare in esso coinvolto consentendo di ipotizzare che il cotrasportatore SGLT1 sia coinvolto direttamente in tale risposta metabolica

Effetti della SGLT2 inibizione su metabolismo glicolipidico e bilancio idro-salino e ruolo del trasportatore NHE3: studio in volontari sani

Background Gli inibitori del co-trasportatore sodio-glucosio di tipo 2 (SGLT2i) esercitano effetti cardioprotettivi. Tra i vari meccanismi, l'inibizione dello scambiatore sodio-idrogeno (NHE), espresso nel cuore e nel tubulo prossimale (NHE3), è stata proposta in studi su modelli animali. Nell’uomo, questo meccanismo, ed i cambiamenti elettrolitici e metabolici associati, non sono stati ancora dimostrati. Soggetti e metodi Venti volontari maschi sani sono stati sottoposti ad uno schema di idratazione standardizzato e assunzione di due compresse di empaglfifozin 25 mg. Le urine sono state raccolte al basale, e dopo 4 e 6 ore insieme ad aliquote di sangue. Nelle cellule tubulari di sfaldamento è stata determinata l’espressione proteica di NHE3 e MAP17. Risultati Il pH urinario aumenta dopo assunzione di empaglifozin (da 5.81±0.5 a 6.11±0.6 dopo 4 ore e 6.16±0.6 dopo 6 ore, p=0.0087 e p=0.0079, rispettivamente) come anche l’output urinario e l’escrezione frazionale di glucosio e sodio mentre si riducono la glicemia e i livelli circolanti di insulina ed aumentano i livelli plasmatici e l’escrezione urinaria dei chetoni. Nelle cellule tubulari di sfaldamento non si osservano variazioni significative nell’espressione di NHE3, pNHE3 o MAP17. In 6 studi di controllo, condotti con lo stesso schema di idratazione ma senza assunzione di empagliflozin, il pH e l’output urinario non mostrano variazioni significative. Conclusioni In soggetti sani, empagliflozin aumenta acutamente il pH urinario inducendo uno shift metabolico verso l'utilizzo dei lipidi e la chetogenesi (grazie ad una rapida diminuzione delle concentrazioni plasmatiche di insulina) senza cambiamenti significativi nell'espressione renale di NHE3

Protein and amino acids in nonalcoholic fatty liver disease

Purpose of review: In this review, the latest evidence on the influence of dietary protein and plasma amino acids in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) is discussed. Recent findings: Increasing protein consumption during weight loss and maintenance may help reduce liver fat content. Conversely, high protein intake characteristic of the unhealthy Western diet is associated with increased NAFLD prevalence and severity. Plasma concentration of several amino acids, including branched-chain (BCAA) and aromatic amino acids (AAA), is altered in NAFLD. Excess amino acid availability contributes to intrahepatic fat accumulation and may reflect poor dietary habits and dysregulation of amino acid metabolic processing in both liver and peripheral tissues. Specific amino acid patterns, characterized by increased BCAA, AAA, alanine, glutamate, lysine levels, and decreased glycine and serine levels, may be used for early detection of NAFLD and noninvasive assessment of its histological severity. Summary: Mechanistic studies in NAFLD have been mostly focused on carbohydrate and fat metabolism, while little is known about the influence of protein and amino acids. Moreover, intervention and observational studies on the relation between protein intake and NAFLD yielded conflicting results. Filling the current knowledge gaps would help define the optimal diet composition for NAFLD prevention and management. Furthermore, metabolomics studies may provide insight into the pathogenesis of NAFLD, identify useful diagnostic and prognostic biomarkers, and unravel novel pharmacological targets and treatment options

High exposure to phthalates is associated with HbA1c worsening in type 2 diabetes subjects with and without edentulism: a prospective pilot study

Abstract Background Phthalates exposure and complete edentulism are related to both low socioeconomic status. No study by far has verified if and to what extent these two conditions are related. We aimed to explore their potential association and interplay in the metabolic control and cardiovascular risk profile. Methods In our small (n = 48) prospective pilot study twenty-four patients with type 2 diabetes (DnE) and twenty-four patients with type 2 diabetes and edentulism (DE) followed for 19 ± 2 months were treated according to best clinical standards. Phthalates’ exposure was evaluated by urinary concentration of di-2-ethylhexylphthalate (DEHP), metabolites, i.e. mono 2-ethylhexyl phthalate (MEHP), mono-2-ethyl-5-oxohexyl phthalate (MEOHP) and mono 2-ethyl-5-hydroxyhexyl phthalate (MEHHP). Results No association between phthalates and edentulism was found, nor did edentulism affect glucose control. Higher phthalates exposure was associated with a glycated haemoglobin worsening. This association was found for all the measured phthalates metabolites, both as a whole (DEHP; r = 0.33, p = 0.0209) and individually: MEHP (r = 0.41, p = 0.0033), MEHHP (r = 0.32, p = 0.028), MEOHP (r = 0.28, p = 0.0386). Conclusions Phthalates are not associated with edentulism but predict the worsening of glucose control in subjects with type 2 diabetes. These findings might prove relevant in identifying novel biomarkers of cardiometabolic risk. Further studies are needed to validate our results and estimate the true potential of phthalates in terms of risk assessment

Normal Versus Slowly Processed Pasta and Post-Prandial Glucose Homeostasis in Healthy Subjects: A Pilot Study

Nutritional science is gaining increasing attention due to the implicit potential to prevent cardio-metabolic diseases. It is also becoming clear that food-making process might influence the metabolic response to the meal. We have conducted a proof-of-concept study to investigate whether slowly processed pasta might positively impact glucose homeostasis. A total of 14 healthy male volunteers underwent two different mixed-meal tests in a randomized order. One meal was composed of 100 g of normally processed pasta and the other 100 g of slowly processed pasta. Each meal was completed with 10 g of olive oil and 10 g of parmesan cheese. Glucose, insulin, and incretin post-prandial responses were assessed at 15, 30, 60, 90, 120, 150, and 180 min. Glucose tolerance, insulin, and incretin response were unaffected by the two different pasta types. However, a slight difference was evident in the shape of the curve of post-prandial insulin (i.e., mildly delayed with the slowly processed pasta). Despite the common belief of a different impact of normally processed and slowly processed pasta on glucose metabolism, they show a superimposable post-prandial metabolic response after a single meal in male healthy individuals. Further studies are required to confirm these results also in chronic, real-life settings and then to translate them to metabolically impaired individuals

Canagliflozin on top of dual renin-angiotensin system blockade in a woman with partial acquired lipodystrophy, type 2 diabetes and severely proteinuric chronic kidney disease: a case report

Sodium glucose cotransporter 2 inhibitors have proven strong efficacy in reducing end-stage renal disease in patients with type 2 diabetes. We are presenting here the case of a 40-year-old woman with acquired partial lipodystrophy, type 2 diabetes and essential hypertension complicated by chronic kidney disease and proteinuria in the nephrotic range. She first came to our attention in 2012; estimated glomerular filtration rate (eGFR) was 41.5 ml/min/1.73 m2 and total proteinuria was 375 mg/24h; she was treated with dual renin angiotensin system blocking. Proteinuria significantly increased during the following years, reaching a nephrotic range (>5 g/day). A kidney biopsy revealed a tubule-interstitial involvement compatible with type 2 diabetes. Leptin replacement therapy, started in 2018, improved glycaemic control and lipid profile, also determining a reduction in insulin total daily dose. In 2019, after the publication of the CREDENCE study, canagliflozin was started on top of losartan and ramipril. After an initial, expected eGFR drop, kidney function stabilized, and albuminuria significantly reduced (from 4120 to 984 mg/24h), while serum potassium showed only minimal increase. At last follow-up (2022) total proteinuria was still reducing (510 mg/24h), while kidney function was substantially unchanged (eGFR 40 ml/min/1.73 m2). This case report suggests that, despite not recommended in international guidelines, the use of SGLT2i in combination with dual renin angiotensin system blockade should be considered in specific conditions and under close clinical monitoring

Phthalates exposure as determinant of albuminuria in type 2 diabetes subjects: a cross-sectional study

CONTEXT: Recent epidemiological observations have reported an association among phthalates exposure and insulin resistance, obesity, and diabetes but have not related exposure to these environmental pollutants with microvascular complications of diabetes. OBJECTIVE: To explore the relationship between phthalates and renal function in subjects with diabetes. DESIGN: Cross-sectional, case-only study. Concentrations of three urinary metabolites of di-2-ethylhexylphthalate were quantified in a spot morning urine sample, normalized for creatinine urinary excretion, and related to clinical parameters and phenotype, adjusting for confounders. PATIENTS: Two hundred and nine patients with diabetes consecutively referred to our clinic. MAIN OUTCOME MEASURES: Relationship between phthalates and renal function [evaluated with estimated glomerular filtration rate (eGFR) and albuminuria]. RESULTS: Creatinine-adjusted urinary concentrations of mono-2-ethylhexyl phthalate (MEHP), mono-2-ethyl-5-oxohexyl phthalate (MEOHP), and mono-2-ethyl-5-hydroxyhexyl phthalate were 7.53 µg/g (range, 4.84 to 12.60), 3.04 µg/g (range, 1.03 to 5.14), and 10.70 µg/g (7.02 to 17.40), respectively. Age, sex, body mass index, diabetes duration, smoking, blood pressure, glycated Hb, and eGFR did not influence their levels. Exposure to MEHP and MEOHP was greater in individuals with microalbuminuria/macroalbuminuria (MEHP, P = 0.0173; MEOHP, P = 0.0306). The fourth vs first quartile showed a greater risk of albuminuria (MEHP: OR, 4.83; 95% CI, 1.45 to 16.06; P = 0.0297; MEOHP: OR, 3.29; 95% CI, 1.08 to 10.04); P = 0.0352). MEOHP was greater (P = 0.034) in subjects with cardiovascular events; MEHP showed a positive trend (P = 0.061). CONCLUSION: Our findings have revealed an association between exposure to di-2-ethylhexylphthalate metabolites and the degree of albuminuria in subjects with diabetes; the lack of a relationship with eGFR suggests their urinary levels are independent of renal function