SIRT1 Serum Concentrations in Lipodystrophic Syndromes.

Lipodystrophies (LDs) are rare, complex disorders of the adipose tissue characterized by selective fat loss, altered adipokine profile and metabolic impairment. Sirtuins (SIRTs) are class III NAD+-dependent histone deacetylases linked to fat metabolism. SIRT1 plays a critical role in metabolic health by deacetylating target proteins in tissue types including liver, muscle, and adipose. Circulating SIRT1 levels have been found to be reduced in obesity and increased in anorexia nervosa and patients experiencing weight loss. We evaluated circulating SIRT1 levels in relation to fat levels in 32 lipodystrophic patients affected by congenital or acquired LDs compared to non-LD subjects (24 with anorexia nervosa, 22 normal weight, and 24 with obesity). SIRT1 serum levels were higher in LDs than normal weight subjects (mean ± SEM 4.18 ± 0.48 vs. 2.59 ± 0.20 ng/mL) and subjects with obesity (1.7 ± 0.39 ng/mL), whereas they were close to those measured in anorexia nervosa (3.44 ± 0.46 ng/mL). Our findings show that within the LD group, there was no relationship between SIRT1 levels and the amount of body fat. The mechanisms responsible for secretion and regulation of SIRT1 in LD deserve further investigation.

Efficacy of multivitamin support following bariatric surgery in patients with obesity: a prospective observational study.

PURPOSE: Bariatric surgery (BS), an effective treatment for severe obesity and its comorbidities, may result in micronutrient and vitamin deficiencies. This monocentric prospective observational study aimed at evaluating the efficacy of a specifically designed vitamin/mineral formula (Bariatrifast, BIOITALIA S.r.l., Italy) for preventing and treating micronutrient deficiencies in patients submitted to BS. METHODS: Twenty patients with severe obesity (mean weight and BMI: 123.5 kg (range 88-174) and 43.3 kg/m2 (range 37-54) respectively) underwent BS (10 vertical sleeve gastrectomy VSG, 10 Roux-en-Y gastric bypass, RYGB). The mean age was 49.9 years (range 27-68). After a presurgical visit (V0), follow-up visits were performed at 1, 3, 6 and 12 months after surgery (V1-V4). Recorded data included weight, height and BMI. A complete blood count, measurement of ferritin, folic acid, vitamin B12, ionized calcium, 25 OH vitamin D, parathyroid hormone (PTH) were obtained. Following BS, patients started the daily oral multivitamin and mineral supplement. RESULTS: All patients achieved a significant weight loss (mean - 34.7 ± 11.8 kg). No deficiencies of various vitamins/micronutrients were detected during the entire study period. The serum concentrations of vitamin B12, 25-OH Vitamin D and folic acid increased over the follow-up period compared with V0 (mean increase 243 ng/L, 23 µg /L, 8 µg/L, respectively). Compared to RYGB, patients who underwent sleeve gastrectomy showed higher levels of 25-OH vitamin D at V2, V3 and V4 (all p < 0.05), and higher levels of Vitamin B12 and folic acid at V4 (p < 0.05 and p < 0.005, respectively). No adverse events were reported. CONCLUSION: Following VSG or RYGB, Bariatrifast administration was associated with normal values of essential micronutrients, and it was well-tolerated without evidence of gastrointestinal side effects. Clinical Trial Registration ClinicalTrials.gov, identifiers NCT06152965.

Brain effect of bariatric surgery in people with obesity.

BACKGROUND/OBJECTIVES: The link between obesity and brain function is a fascinating but still an enigmatic topic. We evaluated the effect of Roux-en-Y gastric bypass (RYGB) on peripheral glucose metabolism, insulin sensitivity, brain glucose utilization and cognitive abilities in people with obesity. SUBJECTS/METHODS: Thirteen subjects with obesity (F/M 11/2; age 44.4 ± 9.8 years; BMI 46.1 ± 4.9 kg/m2) underwent 75-g OGTT during a [18F]FDG dynamic brain PET/CT study at baseline and 6 months after RYGB. At the same timepoints, cognitive performance was tested with Mini Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Trail making test (TMT) and Token test (TT). Glucose, insulin, C-peptide, GLP-1, GIP, and VIP levels were measured during OGTT. Leptin and BDNF levels were measured before glucose ingestion. RESULTS: RYGB resulted in significant weight loss (from 46.1 ± 4.9 to 35.3 ± 5.0 kg/m2; p < 0.01 vs baseline). Insulin sensitivity improved (disposition index: from 1.1 ± 0.2 to 2.9 ± 1.1; p = 0.02) and cerebral glucose metabolic rate (CMRg) declined in various brain areas (all p ≤ 0.01). MMSE and MoCA score significantly improved (p = 0.001 and p = 0.002, respectively). TMT and TT scores showed a slight improvement. A positive correlation was found between CMRg change and HOMA-IR change in the caudate nucleus (ρ = 0.65, p = 0.01). Fasting leptin decreased (from 80.4 ± 13.0 to 16.1 ± 2.4 ng/dl; p = 0.001) and correlated with CMRg change in the hippocampus (ρ = 0.50; p = 0.008). CMRg change was correlated with cognitive scores changes on the TMT and TT (all p = 0.04 or less). CONCLUSIONS: Bariatric surgery improves CMRg directly related to a better cognitive testing result. This study highlights the potential pleiotropic effects of bariatric surgery. TRIAL REGISTRY NUMBER: NCT03414333.

Bariatric surgery restores visual cortical plasticity in nondiabetic subjects with obesity.

BACKGROUND/OBJECTIVES: Obesity leads to changes in synaptic plasticity. We aimed at investigating the impact of bariatric surgery (RYGB) on visual neural plasticity (NP) and its relationship with the main gut peptides, leptin, and brain-derived neurotrophic factor (BDNF). SUBJECTS/METHODS: NP was assessed testing binocular rivalry before and after 2 h of monocular deprivation (index of visual brain plasticity) in 15 subjects with obesity (age 42.3 ± 9.8 years; BMI 46.1 ± 4.9 kg/m2) before and after RYGB. Gut peptides, leptin, and BDNF were obtained at baseline and 6 months after surgery in 13 subjects. RESULTS: A significant reduction in BMI (p < 0.001 vs. baseline) and a significant increase of disposition index (DI, p = 0.02 vs baseline) were observed after RYGB. Total and active GLP-1 release in response to glucose ingestion significantly increased after RYGB, while no changes occurred in VIP, GIP, and BDNF levels. Fasting leptin concentration was lower after RYGB (p = 0.001 vs. baseline). Following RYGB, NP was progressively restored (p < 0.002). NP was correlated with DI and fasting glucose at baseline (r = 0.75, p = 0.01; r = -0.7, p = 0.02; respectively), but not with BMI. A positive correlation between post-pre-RYGB changes in AUCactive GLP-1 and NP was observed (r = 0.70, p < 0.01). Leptin was inversely correlated with NP 6 months after surgery (r = -0.63, p = 0.02). No correlation was observed between GIP, VIP, BDNF, and NP. CONCLUSIONS: Visual plasticity is altered in subjects with obesity, and it can be restored after RYGB. The improvement may be mediated by amelioration of insulin sensitivity, increased GLP-1 levels, and reduced leptin levels.

Complement Factor D (adipsin) Levels Are Elevated in Acquired Partial Lipodystrophy (Barraquer-Simons syndrome).

Complement overactivation has been reported in most patients with Barraquer-Simons syndrome (BSS), a rare form of acquired partial lipodystrophy. Complement Factor D (FD) is a serine protease with a crucial role in the activation of the alternative pathway of the complement system, which is mainly synthesized by adipose tissue. However, its role in the pathogenesis of BSS has not been addressed. In this study, plasma FD concentration was measured in 13 patients with BSS, 20 patients with acquired generalized lipodystrophy, 22 patients with C3 glomerulopathy (C3G), and 50 healthy controls. Gene expression and immunohistochemistry studies were assayed using atrophied adipose tissue from a patient with BSS. We found significantly elevated FD levels in BSS cases compared with the remaining cohorts (p < 0.001). There were no significant differences in FD levels between sexes but FD was strongly and directly associated with age in BSS (r = 0.7593, p = 0.0036). A positive correlation between FD and C3 was seen in patients with C3G, characterized by decreased FD levels due to chronic C3 consumption, but no correlation was detected for BSS. Following mRNA quantification in the patient's adipose tissue, we observed decreased CFD and C3 but elevated C5 transcript levels. In contrast, the increased FD staining detected in the atrophied areas reflects the effects of persistent tissue damage on the adipose tissue, thus providing information on the ongoing pathogenic process. Our results suggest that FD could be a reliable diagnostic biomarker involved in the pathophysiology of BSS by promoting unrestrained local complement system activation in the adipose tissue environment.

Psychopathological and psychiatric evaluation of patients affected by lipodystrophy.

PURPOSE: Lipodystrophy is a collection of rare disorders defined by complete or partial loss of adipose tissue, due to abnormal adipocyte production, function, or distribution; it shares the main metabolic complications with obesity. Aims of the present study were to investigate the psychopathological characteristics of non-HIV lipodystrophic patients in comparison with a group of obese patients, a group of patients affected by oncologic chronic illness, and a control group of healthy subjects. METHODS: All participants were female: 16 non-HIV lipodystrophic women (mean age 42 ± 12 years), 20 women with breast cancer (adenocarcinoma with a positive sentinel lymph node in outpatients awaiting chemotherapy, mean age 44 ± 5 years), 20 obese women (mean age 40 ± 3 years), and 20 healthy women (mean age 40 ± 2 years). Each lipodystrophic patient received a psychiatric assessment, following the diagnostic criteria for DSM-5. Patients and controls received a battery of self-report instruments measuring general psychopathology, body image concerns, eating habits and food craving, and pain concerns. The following psychopathological rating scales were used: SCL-90-R (Symptom Check List) for general psychopathology, BUT (Body Uneasiness Test) for body image, FCQ-T (Food Cravings Questionnaire Trait) for food craving, and WHYMPI (West Haven Yale Multidimensional Pain Inventory) for multidimensional pain inventory. RESULTS: The psychiatric assessment of the 16 lipodystrophic patients revealed: three lifetime mood disorder, six current mood disorder, six lifetime anxiety disorder, five current anxiety disorder, four current somatic symptom disorder with predominant pain, six current binge eating disorder, 11 eating disorder not otherwise specified, two borderline personality disorder, one obsessive-compulsive personality disorder, one avoidant personality disorder, and five personality disorder not otherwise specified. In SCL-90-R scale, the subscale sensitivity showed a significantly higher score in the lipodystrophic and oncologic groups compared to healthy subjects. The subscale paranoid ideation showed a significantly higher score in the lipodystrophic group vs all the other groups. The total score of BUT scale was significantly higher in the lipodystrophic compared to healthy subjects. In WHYMPI scale, the scores of pain interference and family support were significantly higher in the lipodystrophic group. The scores of negative responses were significantly higher in the lipodystrophic group vs healthy subjects. In FCQ-T scale, the score of Cues dimension in lipodystrophic patients was significantly lower as compared with all the other groups. CONCLUSIONS: Our findings suggest that lipodystrophic patients have an increased prevalence of mood, anxiety, pain, and eating disorders. LEVEL OF EVIDENCE: Level III. Evidence obtained from case-control analytic study.

Clinical Characteristics of Patients With Acquired Partial Lipodystrophy: A Multicenter Retrospective Study.

BACKGROUND: Barraquer-Simons syndrome (BSS) is a rare, acquired form of lipodystrophy characterized by progressive loss of upper body subcutaneous fat, which affects face, upper limbs, and trunk. The pathogenesis of the disease is not entirely known and may involve autoimmune mechanisms. AIM: This study aimed to provide a comprehensive picture of the clinical, immunological, and metabolic features of a large cohort of patients with BSS. Our primary objectives included the validation of existing diagnostic tools, the evaluation of novel diagnostic approaches, and the exploration of potential disease triggers or genetic predispositions. SUBJECTS AND METHODS: Twenty-six patients were diagnosed with BSS based on accepted criteria defined by international guidelines. Anthropometric parameters, biochemical tests, organ- and non-organ-specific autoantibodies, HLA status, and screening of the LMNB2 gene were performed. RESULTS: Patients were predominantly females (73%); fat loss occurred mostly during childhood (77%) at a median age of 8 years. Among various anthropometric measures, the ratio between the proportion of fat mass in upper limbs and lower limbs showed the best predictive value for diagnosis. A total of 11.5% of patients had diabetes, 34.6% dyslipidemia, and 26.9% hepatic steatosis. Seventy-five percent of children and 50% of adults had C3 hypocomplementemia; 76% of patients were positive for 1 or more autoantibodies. HLA-DRB1 11:03 had higher allelic frequencies compared with the general population. A single variant in the LMNB2 gene was found in 1 patient. CONCLUSION: BSS has a childhood onset and is often associated with autoimmune diseases. Skinfold thickness measurements and fat assessment by dual energy X-ray absorptiometry are useful tools to identify the disease. C3 hypocomplementemia and the presence of autoantibodies may be used as additional diagnostic supportive criteria but the prevalence of C3 hypocomplementemia may be lower than previously reported.

Proceedings of the annual meeting of the European Consortium of Lipodystrophies (ECLip), Pisa, Italy, 28-29 September 2023.

Lipodystrophy syndromes are rare diseases primarily affecting the development or maintenance of the adipose tissue but are also distressing indirectly multiple organs and tissues, often leading to reduced life expectancy and quality of life. Lipodystrophy syndromes are multifaceted disorders caused by genetic mutations or autoimmunity in the vast majority of cases. While many subtypes are now recognized and classified, the disease remains remarkably underdiagnosed. The European Consortium of Lipodystrophies (ECLip) was founded in 2014 as a non-profit network of European centers of excellence working in the field of lipodystrophies aiming at promoting international collaborations to increase basic scientific understanding and clinical management of these syndromes. The network has developed a European Patient Registry as a collaborative research platform for consortium members. ECLip and ECLip registry activities involve patient advocacy groups to increase public awareness and to seek advice on research activities relevant from the patients perspective. The annual ECLip congress provides updates on the research results of various network groups members.

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.

Oxidative and DNA damage in obese patients undergoing bariatric surgery: A one-year follow-up study.

The pathogenesis of obesity and related comorbidities has long been associated with oxidative stress. The excess of adipose tissue contributes to the production of free radicals that sustain both a local and a systemic chronic inflammatory state, whereas its reduction can bring to an improvement in inflammation and oxidative stress. In our work, using the fluorescent lipid probe BODIPY® 581/591 C11 and the γH2AX foci assay, a well-known marker of DNA double strand breaks (DSB), we evaluated the extent of cell membrane oxidation and DNA damage in peripheral blood lymphocytes of normal weight (NW) controls and obese patients sampled before and after bariatric surgery. Compared to NW controls, we observed a marked increase in both the frequencies of oxidized cells or nuclei exhibiting phosphorylation of histone H2AX in preoperatory obese patients. After bariatric surgery, obese patients, resampled over one-year follow-up, improved oxidative damage and reduced the presence of DSB. In conclusion, the present study highlights the importance for obese patients undergoing bariatric surgery to also monitor these molecular markers during their postoperative follow-up.

Obesity, Hyperfiltration, and Early Kidney Damage: A New Formula for the Estimation of Creatinine Clearance.

CONTEXT: Glomerular hyperfiltration may represent a direct pathogenetic link between obesity and kidney disease. The most widely used methods to estimate creatine clearance such as Cockroft-Gault (CG), Modification of Diet in Renal Disease (MDRD), and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) have not been validated in subjects with obesity. OBJECTIVE: The performance of prediction formulas was compared with measured creatinine clearance (mCrCl) in subjects with obesity. METHODS: The study population included 342 patients with obesity (mean BMI 47.6 kg/m2) without primary kidney disease. A urine collection was performed over 24 hours for measurement of CrCl. RESULTS: mCrCl increased with body weight. The CG formula showed an overestimation at high CrCl, whereas an underestimation resulted from CKD-EPI and MDRD. To improve the accuracy of estimated CrCl (eCrCl), a new CG-based formula was developed:53+0.7×(140-Age)×Weight/(96xSCr)×(0.85iffemale)A cut-off point for BMI of 32 kg/m2 was identified, at which the new formula may be applied to improve eCrCl. CONCLUSION: In patients with obesity the glomerular filtration rate increases with body weight, and it is associated with the presence of albuminuria, suggesting an early kidney injury. We propose a novel formula that improves the accuracy of eCrCl to avoid missed diagnoses of hyperfiltration in patients with obesity.

Characterization and Clinical Association of Autoantibodies Against Perilipin 1 in Patients With Acquired Generalized Lipodystrophy.

Acquired generalized lipodystrophy (AGL) is a rare condition characterized by massive loss of adipose tissue through the body, causing severe metabolic complications. Autoimmune destruction of adipocytes is strongly suspected based on the frequent association of AGL with autoimmune disorders. In 2018, autoantibodies against perilipin 1 (PLIN1) were identified in three patients with autoimmune-associated AGL. However, the pathogenic mechanism and clinical impact of anti-PLIN1 remain unsolved. The prevalence of anti-PLIN1 autoantibodies in an AGL cohort of 40 patients was 50% (20 of 40). Among positive patients, 10 had the autoimmune variety and 10 had panniculitis-associated AGL. The IgG isotype was predominant, although some IgM antibodies were detected. Epitope-mapping studies did not identify a single, major epitope. Instead, autoantibodies typically bound to several different peptides, among which the central (233-405) domain was detected in all antibody-positive patients, for both IgG and IgM autoantibodies. In-depth epitope mapping indicated that anti-PLIN1 autoantibodies predominantly recognize the αß-hydrolase domain containing 5 (ABHD5) binding site (383-405). Autoantibodies dose-dependently blocked the binding of PLIN1 to ABHD5 and caused a dislocation of ABHD5 toward the cytosol, leading to an increase in lipolysis and lipase activities. Finally, anti-PLIN1 titers significantly correlated with the amount of fat loss, metabolic control impairment, and severity of liver injury. Our data strongly support that anti-PLIN1 autoantibodies are a diagnostic biomarker and a cause of lipodystrophy in patients with AGL.

A new mutation in the CAVIN1/PTRF gene in two siblings with congenital generalized lipodystrophy type 4: case reports and review of the literature.

Lipodystrophy syndromes are characterized by a progressive metabolic impairment secondary to adipose tissue dysfunction and may have a genetic background. Congenital generalized lipodystrophy type 4 (CGL4) is an extremely rare subtype, caused by mutations in the polymerase I and transcript release factor (PTRF) gene. It encodes for a cytoplasmatic protein called caveolae-associated protein 1 (Cavin-1), which, together with caveolin 1, is responsible for the biogenesis of caveolae, being a master regulator of adipose tissue expandability. Cavin-1 is expressed in several tissues, including muscles, thus resulting, when dysfunctional, in a clinical phenotype characterized by the absence of adipose tissue and muscular dystrophy. We herein describe the clinical phenotypes of two siblings in their early childhood, with a phenotype characterized by a generalized reduction of subcutaneous fat, muscular hypertrophy, distinct facial features, myopathy, and atlantoaxial instability. One of the siblings developed paroxysmal supraventricular tachycardia leading to cardiac arrest at 3 months of age. Height and BMI were normal. Blood tests showed elevated CK, a mild increase in liver enzymes and triglycerides levels, and undetectable leptin and adiponectin concentrations. Fasting glucose and HbA1c were normal, while Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) was mildly elevated. Both patients were hyperphagic and had cravings for foods rich in fats and sugars. Genetic testing revealed a novel pathogenic mutation of the CAVIN1/PTRF gene (NM_012232 exon1:c T21A:p.Y7X) at the homozygous state. The diagnosis of lipodystrophy can be challenging, often requiring a multidisciplinary approach, given the pleiotropic effect, involving several tissues. The coexistence of generalized lack of fat, myopathy with elevated CK levels, arrhythmias, gastrointestinal dysmotility, and skeletal abnormalities should prompt the suspicion for the diagnosis of CGL4, although phenotypic variability may occur.

Ketogenic Diet and Weight Loss: Is There an Effect on Energy Expenditure?

A dysregulation between energy intake (EI) and energy expenditure (EE), the two components of the energy balance equation, is one of the mechanisms responsible for the development of obesity. Conservation of energy equilibrium is deemed a dynamic process and alterations of one component (energy intake or energy expenditure) lead to biological and/or behavioral compensatory changes in the counterpart. The interplay between energy demand and caloric intake appears designed to guarantee an adequate fuel supply in variable life contexts. In the past decades, researchers focused their attention on finding efficient strategies to fight the obesity pandemic. The ketogenic or "keto" diet (KD) gained substantial consideration as a potential weight-loss strategy, whereby the concentration of blood ketones (acetoacetate, 3-ß-hydroxybutyrate, and acetone) increases as a result of increased fatty acid breakdown and the activity of ketogenic enzymes. It has been hypothesized that during the first phase of KDs when glucose utilization is still prevalent, an increase in EE may occur, due to increased hepatic oxygen consumption for gluconeogenesis and for triglyceride-fatty acid recycling. Later, a decrease in 24-h EE may ensue due to the slowing of gluconeogenesis and increase in fatty acid oxidation, with a reduction of the respiratory quotient and possibly the direct action of additional hormonal signals.

Circulating Levels of MiRNAs From 320 Family in Subjects With Lipodystrophy: Disclosing Novel Signatures of the Disease.

Lipodystrophy (LD) indicates a group of rare disorders, with generalized or partial loss of white adipose tissue (WAT) often associated with metabolic derangements. Heterogeneity/wide spectrum of the disease and lack of biomarkers make diagnosis often difficult. MicroRNAs are important to maintain a correct WAT function and WAT is a source of circulating miRNAs (cmiRs). miRNAs from 320 family were previously detected in the WAT and variably associated to the metabolic syndrome. Our aim was then to investigate if LD can result in altered abundance of cmiRs-320. We collected samples from a cohort of LD subjects of various subtypes and from age matched controls. Use of quantitative PCR determined that cmiRs- 320a-3p, 320b, 320c, 320e are upregulated, while 320d is downregulated in LD. CmiRs-320 power as classifiers was more powerful in the most extreme and defined forms of LD, including the generalized and the Dunnigan subtypes. cmiR-320a-3p showed significant inverse relationships with plasma leptin (P < 0.0001), typically low in LD. The hepatic enzymes gamma-glutamyl transferase (GGT), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and the marker of inflammation C-reactive protein (CRP) were inversely related to cmiR 320d (P < 0.05, for CRP and GGT; P < 0.01, for AST and ALT). Gene ontology analysis revealed cell-cell adhesion as a process regulated by 320 miRNAs targets, thus disclosing a novel route to investigate origin of WAT loss/dysfunction. In conclusion, cmiRs-320 constitute novel biomarkers of LD, abundance of miR320a-3p is inversely associated to indicators related to WAT function, while downregulation of cmiR-320d predicts an altered hepatic profile and higher inflammation.

Proceedings of the annual meeting of the European Consortium of Lipodystrophies (ECLip) Cambridge, UK, 7-8 April 2022.

Lipodystrophy syndromes are rare diseases with defects in the development or maintenance of adipose tissue, frequently leading to severe metabolic complications. They may be genetic or acquired, with variable clinical forms, and are largely underdiagnosed. The European Consortium of Lipodystrophies, ECLip, is a fully functional non-profit network of European centers of excellence working in the field of lipodystrophies. It provides a favorable environment to promote large Europe-wide and international collaborations to increase the basic scientific understanding and clinical management of these diseases. It works with patient advocacy groups to increase public awareness. The network also promotes a European Patient Registry of lipodystrophies, as a collaborative research platform for consortium members. The annual congress organized gives an update of the findings of network research groups, highlighting clinical and fundamental aspects. The talks presented during the meeting in Cambridge, UK, in 2022 are summarized in these minutes.

Cellular program controlling the recovery of adipose tissue mass: An in vivo imaging approach.

The cellular program responsible for the restoration of adipose tissue mass after weight loss is largely uncharacterized. Leptin mRNA levels are highly correlated with adipose tissue mass, and leptin expression can thus be used as a surrogate for changes in the amount of adipose tissue. To further study the responses of adipocytes to changes in weight, we created a transgenic mouse expressing the luciferase reporter gene under the control of leptin regulatory sequences, which allows noninvasive imaging of the leptin expression of mice in vivo. We used these animals to show that weight loss induced by fasting or leptin treatment results in the retention of lipid-depleted adipocytes in adipose depots. To further study the cellular response to weight regain after leptin treatment, a leptin withdrawal protocol was used to induce a state of acute leptin deficiency in wild type mice. Acute leptin deficiency led to the transient deposition of large amounts of glycogen within pre-existing, lipid-depleted adipocytes. This was followed by rapid reaccumulation of lipid. Transcriptional profiling revealed that this cellular response was associated with induction of mRNAs for the entire pathway of enzymes necessary to convert glucose into acetyl-CoA and glycerol, key substrates for the synthesis of triglycerides.

Autoimmunity in lipodystrophy syndromes.

Lipodystrophy syndromes are rare, heterogeneous disorders characterized by the complete or partial deficiency of adipose tissue and are classified according to the extent of fat loss in generalized or partial subtypes, or based on the pathogenic mechanisms in genetic or acquired. While in most cases of congenital forms of lipodystrophy a genetic alteration can be identified, the pathogenic mechanisms responsible for the acquired diseases are not fully clarified. Based on the evidence of a positive association between most acquired lipodystrophies and autoimmune disorders including immune mediated alterations in the adipose tissue of patients affected by acquired lipodystrophy, a reaction against white adipose tissue antigens is postulated. Recent acquisitions have shed new light on the possible pathogenic mechanisms and identified novel forms of acquired lipodystrophy which are possibly immune-mediated. The aim of this review is to give an update on acquired lipodystrophies describing pathogenic mechanisms involved and the relationships between acquired lipodystrophies and other autoimmune disorders. Larger studies based on international disease registries are needed to collect accurate information on the prevalence, risk factors, genetic predisposition, natural history, disease markers and treatment efficacy of these ultrarare disorders.

Lipodystrophy as a Late Effect after Stem Cell Transplantation.

Survivors of childhood cancer are at high risk of developing metabolic diseases in adulthood. Recently, several patients developing partial lipodystrophy following hematopoietic stem cell transplantation (HSCT) have been described. In this review, we summarize the cases described so far and discuss potential underlying mechanisms of the disease. The findings suggest that HSCT-associated lipodystrophies may be seen as a novel form of acquired lipodystrophy.

Partial Lipodystrophy and LMNA p.R545H Variant.

Laminopathies are disorders caused by LMNA gene mutations, which selectively affect different tissues and organ systems, and present with heterogeneous clinical and pathological traits. The molecular mechanisms behind these clinical differences and tissue specificity have not been fully clarified. We herein examine the case of a patient carrying a heterozygous LMNA c.1634G>A (p.R545H) variant with a mild, transient myopathy, who was referred to our center for the suspicion of lipodystrophy. At physical examination, an abnormal distribution of subcutaneous fat was noticed, with fat accumulation in the anterior regions of the neck, resembling the fat distribution pattern of familial partial lipodystrophy type 2 (FPLD2). The R545H missense variant has been found at very low allelic frequency in public databases, and in silico analysis showed that this amino acid substitution is predicted to have a damaging role. Other patients carrying the heterozygous LMNA p.R545H allele have shown a marked clinical heterogeneity in terms of phenotypic body fat distribution and severity of organ system involvement. These findings indicate that the LMNA p.R545H heterozygous variant exhibits incomplete penetrance and highly variable expressivity. We hypothesized that additional genetic factors, epigenetic mechanisms, or environmental triggers might explain the variable expressivity of phenotypes among various patients.