Lipodystrophies: rare disorders causing metabolic syndrome

Involvement of a battery of investigated genes in lipid droplet pathophysiology and associated comorbidities

Lipid droplets (LDs) are highly specialized energy storage organelles involved in the maintenance of lipid homoeostasis by regulating lipid flux within white adipose tissue (WAT). The physiological function of adipocytes and LDs can be compromised by mutations in several genes, leading to NEFA-induced lipotoxicity, which ultimately manifests as metabolic complications, predominantly in the form of dyslipidemia, ectopic fat accumulation, and insulin resistance. In this review, we delineate the effects of mutations and deficiencies in genes - CIDEC, PPARG, BSCL2, AGPAT2, PLIN1, LIPE, LMNA, CAV1, CEACAM1, and INSR - involved in lipid droplet metabolism and their associated pathophysiological impairments, highlighting their roles in the development of lipodystrophies and metabolic dysfunction.

Current Insights into the Effects of Dietary α-Linolenic Acid Focusing on Alterations of Polyunsaturated Fatty Acid Profiles in Metabolic Syndrome

The plant-derived α-linolenic acid (ALA) is an essential n-3 acid highly susceptible to oxidation, present in oils of flaxseeds, walnuts, canola, perilla, soy, and chia. After ingestion, it can be incorporated in to body lipid pools (particularly triglycerides and phospholipid membranes), and then endogenously metabolized through desaturation, elongation, and peroxisome oxidation to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), with a very limited efficiency (particularly for DHA), beta-oxidized as an energy source, or directly metabolized to C18-oxilipins. At this moment, data in the literature about the effects of ALA supplementation on metabolic syndrome (MetS) in humans are inconsistent, indicating no effects or some positive effects on all MetS components (abdominal obesity, dyslipidemia, impaired insulin sensitivity and glucoregulation, blood pressure, and liver steatosis). The major effects of ALA on MetS seem to be through its conversion to more potent EPA and DHA, the impact on the n-3/n-6 ratio, and the consecutive effects on the formation of oxylipins and endocannabinoids, inflammation, insulin sensitivity, and insulin secretion, as well as adipocyte and hepatocytes function. It is important to distinguish the direct effects of ALA from the effects of EPA and DHA metabolites. This review summarizes the most recent findings on this topic and discusses the possible mechanisms.

Evodiamine inhibits growth of vemurafenib drug-resistant melanoma via suppressing IRS4/PI3K/AKT signaling pathway

Evodiamine, a novel alkaloid, was isolated from the fruit of tetradium. It exerts a diversity of pharmacological effects and has been used to treat gastropathy, hypertension, and eczema. Several studies reported that evodiamine has various biological effects, including anti-nociceptive, anti-bacterial, anti-obesity, and anti-cancer activities. However, there is no research regarding its effects on drug-resistant cancer. This study aimed to investigate the effect of evodiamine on human vemurafenib-resistant melanoma cells (A375/R cells) proliferation ability and its mechanism. Cell activity was assessed using the cell counting kit-8 (CCK-8) method. Flow cytometry assay was used to assess cell apoptosis and cell cycle. A xenograft model was used to analyze the inhibitory effects of evodiamine on tumor growth. Bioinformatics analyses, network pharmacology, and molecular docking were used to explore the potential mechanism of evodiamine in vemurafenib-resistant melanoma. RT-qPCR and Western blotting were performed to reveal the molecular mechanism. The alkaloid extract of the fruit of tetradium, evodiamine showed the strongest tumor inhibitory effect on vemurafenib-resistant melanoma cells compared to treatment with vemurafenib alone. Evodiamine inhibited vemurafenib-resistant melanoma cell growth, proliferation, and induced apoptosis, conforming to a dose-effect relationship and time-effect relationship. Results from network pharmacology and molecular docking suggested that evodiamine might interact with IRS4 to suppress growth of human vemurafenib-resistant melanoma cells. Interestingly, evodiamine suppressed IRS4 expression and then inhibited PI3K/AKT signaling pathway, and thus had the therapeutic action on vemurafenib-resistant melanoma.

Lipodystrophies in non-insulin-dependent children: Treatment options and results from recombinant human leptin therapy

Lipodystrophy is a general definition containing different pathologies which, except for those observed in insulin-treated subjects falling outside the scope of this paper, are characterized by total or partial lack of body fat, that, according to the amount of missing adipose tissue, are divided in generalized or partial lipodystrophy. These diseases are characterized by leptin deficiency, which often leads to metabolic derangement, causing insulin resistance, dyslipidemia, and increasing cardiovascular risk. In this narrative review, we presentend the clinical presentation of different types of lipodystrophies and metabolic unbalances related to disease in children and adolescents, focusing on the main treatment options and the novel results from recombinant human leptin (metreleptin) therapy. Milestones in the management of lipodystrophy include lifestyle modification as diet and physical activity, paired with hypoglycemic drugs, insulin, hypolipidemic drugs, and other drugs with the aim of treating lipodystrophy complications. Metreleptin has been recently approved for pediatric patients with general lipodystrophy (GL)> 2 years of age and for children with partial lipodystrophy (PL)> 12 years of age not controlled with conventional therapies. New therapeutic strategies are currently being investigated, especially for patients with PL forms, specifically, liver-targeted therapies. Further studies are needed to achieve the most specific and precise treatment possible.

Familial Partial Lipodystrophy-Literature Review and Report of a Novel Variant in PPARG Expanding the Spectrum of Disease-Causing Alterations in FPLD3

Familial partial lipodystrophy (FPLD) is a rare genetic disorder characterized by the selective loss of adipose tissue. Its estimated prevalence is as low as 1 in 1 million. The deficiency of metabolically active adipose tissue is closely linked with a wide range of metabolic complications, such as insulin resistance, lipoatrophic diabetes, dyslipidemia with severe hypertriglyceridemia, hypertension or hepatic steatosis. Moreover, female patients often develop hyperandrogenism, hirsutism, polycystic ovaries and infertility. The two most common types are FPLD type 2 and 3. Variants within LMNA and PPARG genes account for more than 50% of all reported FPLD cases. Because of its high heterogeneity and rarity, lipodystrophy can be easily unrecognized or misdiagnosed. To determine the genetic background of FPLD in a symptomatic woman and her close family, an NGS custom panel was used to sequence LMNA and PPARG genes. The affected patient presented fat deposits in the face, neck and trunk, with fat loss combined with muscular hypertrophy in the lower extremities and hirsutism, all features first manifesting at puberty. Her clinical presentation included metabolic disturbances, including hypercholesterolemia with severe hypertriglyceridemia, diabetes mellitus and hepatic steatosis. This together with her typical fat distribution and physical features raised a suspicion of FPLD. NGS analysis revealed the presence of missense heterozygous variant c.443G>A in exon 4 of PPARG gene, causing glycine to glutamic acid substitution at amino acid position 148, p.(Gly148Glu). The variant was also found in the patient’s mother and son. The variant was not previously reported in any public database. Based on computational analysis, crucial variant localization within DNA-binding domain of PPARγ, available literature data and the variant cosegregation in the patient’s family, novel c.443G>A variant was suspected to be causative. Functional testing is needed to confirm the pathogenicity of the novel variant. Inherited lipodystrophy syndromes represent a heterogenous group of metabolic disorders, whose background often remains unclear. A better understating of the genetic basis would allow earlier diagnosis and targeted treatment implementation.

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.

JAZF1 heterozygous knockout mice show altered adipose development and metabolism

BACKGROUND

Juxtaposed with another zinc finger protein 1 (JAZF1) is associated with metabolic disorders, including type 2 diabetes mellitus (T2DM). Several studies showed that JAZF1 and body fat mass are closely related. We attempted to elucidate the JAZF1 functions on adipose development and related metabolism using in vitro and in vivo models.

RESULTS

The JAZF1 expression was precisely regulated during adipocyte differentiation of 3T3-L1 preadipocyte and mouse embryonic fibroblasts (MEFs). Homozygous JAZF1 deletion (JAZF1-KO) resulted in impaired adipocyte differentiation in MEF. The JAZF1 role in adipocyte differentiation was demonstrated by the regulation of PPARγ-a key regulator of adipocyte differentiation. Heterozygous JAZF1 deletion (JAZF1-Het) mice fed a normal diet (ND) or a high-fat diet (HFD) had less adipose tissue mass and impaired glucose homeostasis than the control (JAZF1-Cont) mice. However, other metabolic organs, such as brown adipose tissue and liver, were negligible effect on JAZF1 deficiency.

CONCLUSION

Our findings emphasized the JAZF1 role in adipocyte differentiation and related metabolism through the heterozygous knockout mice. This study provides new insights into the JAZF1 function in adipose development and metabolism, informing strategies for treating obesity and related metabolic disorders.

Targeted massively parallel sequencing for congenital generalized lipodystrophy

Objective

Our aim is to establish genetic diagnosis of congenital generalized lipodystrophy (CGL) using targeted massively parallel sequencing (MPS), also known as next-generation sequencing (NGS).

Methods

Nine unrelated individuals with a clinical diagnosis of CGL were recruited. We used a customized panel to capture genes related to genetic lipodystrophies. DNA libraries were generated, sequenced using the Illumina MiSeq, and bioinformatics analysis was performed.

Results

An accurate genetic diagnosis was stated for all nine patients. Four had pathogenic variants in AGPAT2 and three in BSCL2. Three large homozygous deletions in AGPAT2 were identified by copy-number variant analysis.

Conclusion

Although we have found allelic variants in only 2 genes related to CGL, the panel was able to identify different variants including deletions that would have been missed by Sanger sequencing. We believe that MPS is a valuable tool for the genetic diagnosis of multi-genes related diseases, including CGL.

Effects of Metreleptin on Patient Outcomes and Quality of Life in Generalized and Partial Lipodystrophy

Generalized and partial lipodystrophy are rare and complex diseases with progressive clinical and humanistic burdens stemming from selective absence of subcutaneous adipose tissue, which causes reduced energy storage capacity and a deficiency of adipokines such as leptin. Treatment options were limited before leptin replacement therapy (metreleptin) became available. This retrospective study evaluates both clinical and humanistic consequences of the disease and treatment. Chart data were abstracted from a cohort of metreleptin-treated patients with generalized and partial lipodystrophy (n = 112) treated at the US National Institutes of Health. To quantify the quality-of-life consequences of the lipodystrophy disease attributes recorded in chart data, a discrete choice experiment was completed in 6 countries (US, n = 250; EU, n = 750). Resulting utility decrements were used to estimate the quality-adjusted life-year consequences of changes in lipodystrophy attribute prevalence before and after metreleptin. In addition to metabolic impairment, patients with generalized and partial lipodystrophy experienced a range of lipodystrophy consequences, including liver abnormality (94%), hyperphagia (79%), impaired physical appearance (77%), kidney abnormality (63%), reproductive dysfunction (80% of females of reproductive age), and pancreatitis (39%). Improvement was observed in these attributes following initiation of metreleptin. Quality-adjusted life-year gains associated with 12 months of treatment with metreleptin were estimated at 0.313 for generalized and 0.117 for partial lipodystrophy, reducing the gap in quality of life between untreated lipodystrophy and perfect health by approximately 59% and 31%, respectively. This study demonstrates that metreleptin is associated with meaningful clinical and quality-of-life improvements.

The Metabolic Equivalent BMI in Patients with Familial Partial Lipodystrophy (FPLD) Compared with Those with Severe Obesity

OBJECTIVE

This study aimed to investigate the shortcoming of BMI as a measurement of adiposity in patients with familial partial lipodystrophy (FPLD).

METHODS

Two different matching procedures were used to compare 55 FPLD versus control patients with severe obesity (N = 548 patients) to study the relationship between body weight, fat distribution, and metabolic diseases, such as diabetes mellitus, hypertriglyceridemia, and nonalcoholic steatohepatitis. In MATCH1, the patients with FPLD were matched to controls with obesity (OCs) by truncal mass, and in MATCH2, the patients with FPLD were matched to OCs with respect to glucose control.

RESULTS

With MATCH1, the FPLD group had worse glycemic control (hemoglobin A1c 8.2% ± 1.6% vs. 5.9% ± 0.9%), higher triglycerides (884 ± 1,190 mg/dL vs. 139 ± 79 mg/dL), and lower leptin (20.5 ± 15.8 ng/mL vs. 41.9 ± 29.4 ng/mL, P < 0.001 for all comparisons). In MATCH2, metabolic comorbidity-matched FPLD patients had significantly lower BMI compared with OCs (29.5 ± 5.7 kg/m2 vs. 38.6 ± 5.2 kg/m2 , P < 0.001).

CONCLUSIONS

Patients with FPLD with similar truncal mass have worse metabolic profiles than non-FPLD OCs. The differential BMI between the FPLD and OCs, when matched for their metabolic comorbidities, approximates 8.6 BMI units.

Magnetic resonance spectroscopy to assess hepatic steatosis in patients with lipodystrophy

BACKGROUND/AIMS

Lipodystrophy is a rare metabolic disorder characterized by near total or partial lack of subcutaneous adipose tissue and associated with insulin resistance. We aimed to evaluate the efficacy of magnetic resonance spectroscopy imaging (MRS) to explore the fat content of the liver in patients with lipodystrophy and to determine the relationship between the liver fat accumulation and clinical presentations of lipodystrophy.

MATERIALS AND METHODS

Between July 2014 and February 2016, 34 patients with lipodystrophy were assessed by MRS for quantification of hepatic steatosis. All patients had metabolic abnormalities associated with insulin resistance. Metabolic parameters and the MRS findings were analyzed to identify potential correlations between the liver fat content and disease severity.

RESULTS

The MRS fat ratios (MRS-FR) were markedly higher, indicating severe hepatic steatosis in lipodystrophy. Patients with generalized and partial lipodystrophy had comparable levels of MRS-FRs, although patients with generalized lipodystrophy were significantly younger. Patients with genetically based lipodystrophy had elevated MRS-FR compared to those with acquired lipodystrophy (p=0.042). The MRS-FR was positively correlated with liver enzyme alanine aminotransferase (p=0.028) and serum adiponectin (p=0.043).

CONCLUSION

Our data suggest that MRS might be an effective, noninvasive imaging method to quantify hepatic fat content in patients with lipodystrophy. Further studies are needed to validate the technique and threshold values which would allow accurate comparison of data acquired by different machines and centers.

Catecholamines suppress fatty acid re-esterification and increase oxidation in white adipocytes via STAT3

Catecholamines stimulate the mobilization of stored triglycerides in adipocytes to provide fatty acids (FAs) for other tissues. However, a large proportion is taken back up and either oxidized or re-esterified. What controls the disposition of these FAs in adipocytes remains unknown. Here, we report that catecholamines redirect FAs for oxidation through the phosphorylation of signal transducer and activator of transcription 3 (STAT3). Adipocyte STAT3 is phosphorylated upon activation of β-adrenergic receptors, and in turn suppresses FA re-esterification to promote FA oxidation. Adipocyte-specific Stat3 KO mice exhibit normal rates of lipolysis, but exhibit defective lipolysis-driven oxidative metabolism, resulting in reduced energy expenditure and increased adiposity when they are on a high-fat diet. This previously unappreciated, non-genomic role of STAT3 explains how sympathetic activation can increase both lipolysis and FA oxidation in adipocytes, revealing a new regulatory axis in metabolism.

Metabolically Healthy Obesity: Criteria, Epidemiology, Controversies, and Consequences

PURPOSE OF REVIEW

To present a comprehensive overview regarding criteria, epidemiology, and controversies that have arisen in the literature about the existence and the natural course of the metabolic healthy phenotype.

RECENT FINDINGS

The concept of metabolically healthy obesity (MHO) implies that a subgroup of obese individuals may be free of the cardio-metabolic risk factors that commonly accompany obese subjects with adipose tissue dysfunction and insulin resistance, known as having metabolic syndrome or the metabolically unhealthy obesity (MUO) phenotype. Individuals with MHO appear to have a better adipose tissue function, and are more insulin sensitive, emphasizing the central role of adipose tissue function in metabolic health. The reported prevalence of MHO varies widely, and this is likely due the lack of universally accepted criteria for the definition of metabolic health and obesity. Also, the natural course and the prognostic value of MHO is hotly debated but it appears that it likely evolves towards MUO, carrying an increased risk for cardiovascular disease and mortality over time. Understanding the pathophysiology and the determinants of metabolic health in obesity will allow a better definition of the MHO phenotype. Furthermore, stratification of obese subjects, based on metabolic health status, will be useful to identify high-risk individuals or subgroups and to optimize prevention and treatment strategies to compact cardio-metabolic diseases.

Clinical correlations and genetic associations of metabolic syndrome in the United Arab Emirates

BACKGROUND

Metabolic syndrome (MetS) contributes to increased risk of morbidity and mortality. The United Arab Emirates (UAE) has a high prevalence of MetS which may be linked to modifiable and genetic risk factors in the local population. The association between MetS as a phenotype and key genetic variants in the UAE has not been investigated. This study reports on the clinical, biochemical and genetic associations of MetS and its risk factors to improve individualized medicine outcomes.

METHODS

There were 471 subjects included in this cross-sectional study, 367 with MetS and 104 without MetS. Along with clinical and laboratory parameters, multiple risk genetic variants were tested for their association with MetS, which include 49 variants that have previously been shown to be linked with MetS development as a phenotype, 116 variants for association with waist-hip ratio (WHR), 398 variants with body-mass index (BMI), 213 variants with T2DM and insulin resistance, 307 variants with different lipid traits, 308 variants with blood pressure traits, and 64 variants with coronary and cerebrovascular accidents.

RESULTS

Patients with MetS had higher rates of type 2 diabetes mellitus (T2DM), hypertension and dyslipidemia (p < 0.0001). Waist circumference and T2DM were identified as the key risk factors for MetS development. Individuals with MetS were also found to have a higher rate of clinical complications than those without MetS (76% vs. 52%). Several gene variants including those of the FTO gene were found to be associated with a predisposition to developing MetS or some of its components (P_FTO ~0.005-0.009).

CONCLUSIONS

This study showed associations between MetS as well as clinical factors contributing to MetS and specific genetic and metabolic risk factors, providing an insight into the metabolic and genetic links to disease development. Knowledge with respect to population specific risk markers including at risk genotypes will help in early identification of individuals with increased susceptibility to MetS in the UAE and provide the opportunity for timely intervention to prevent or delay the onset of MetS.

Novel compound heterozygous variant of BSCL2 identified by whole exome sequencing and multiplex ligation‑dependent probe amplification in an infant with congenital generalized lipodystrophy

Congenital generalized lipodystrophy (CGL) is a clinically and genetically heterogeneous condition with autosomal recessive inheritance. CGL is classified into four subtypes on the basis of causative genes. This study reported on a 2-month-old male infant diagnosed with CGL with generalized lipoatrophy and skin hyperpigmentation. Whole exome sequencing (WES) identified a heterozygous small insertion (c.545_546insCCG) in Berardinelli-Seip congenital lipodystrophy 2 (BSCL2) that was inherited from the infant's mother. Copy number variation analysis using exome data suggested a heterozygous deletion involving exon 3 that was inherited from the infant's father. This finding was confirmed by multiplex ligation-dependent probe amplification test. Gap-PCR revealed breakpoints and confirmed a 1274 bp heterozygous deletion encompassing exon 3 of BSCL2 (c.213-1081_c.294+111). This deletion is different from the founder 3.3 kb deletion involving exon 3 of BSCL2 in the Peruvian population. An 11-bp microhomology at the breakpoints may mediate the deletion, and its presence indicates the independent origins of the exon 3 deletion between Chinese and Peruvian populations. The present results expanded the mutational spectrum of the BSCL2 gene in the Chinese population and suggested that introns 2 and 3 of BSCL2 are prone to recombination. Thus, exon 3 deletion should be considered for patients with CGL2 when only one BSCL2 variant is detected through WES.

Current Diagnosis, Treatment and Clinical Challenges in the Management of Lipodystrophy Syndromes in Children and Young People

Lipodystrophy is a heterogeneous group of disorders characterized by lack of body fat in characteristic patterns, which can be genetic or acquired. Lipodystrophy is associated with insulin resistance that can develop in childhood and adolescence, and usually leads to severe metabolic complications. Diabetes mellitus, hypertriglyceridemia, and hepatic steatosis ordinarily develop in these patients, and most girls suffer from menstrual abnormalities. Severe complications develop at a relatively young age, which include episodes of acute pancreatitis, renal failure, cirrhosis, and complex cardiovascular diseases, and all of these are associated with serious morbidity. Treatment of lipodystrophy consists of medical nutritional therapy, exercise, and the use of anti-hyperglycemic and lipid-lowering agents. New treatment modalities, such as metreleptin replacement, promise much in the treatment of metabolic abnormalities secondary to lipodystrophy. Current challenges in the management of lipodystrophy in children and adolescents include, but are not limited to: (1) establishing specialized centers with experience in providing care for lipodystrophy presenting in childhood and adolescence; (2) optimizing algorithms that can provide some guidance for the use of standard and novel therapies to ensure adequate metabolic control and to prevent complications; (3) educating patients and their parents about lipodystrophy management; (4) improving patient adherence to chronic therapies; (5) reducing barriers to access to novel treatments; and (5) improving the quality of life of these patients and their families.

An overview of lipodystrophy and the role of the complement system

The complement system is a major component of innate immunity playing essential roles in the destruction of pathogens, the clearance of apoptotic cells and immune complexes, the enhancement of phagocytosis, inflammation, and the modulation of adaptive immune responses. During the last decades, numerous studies have shown that the complement system has key functions in the biology of certain tissues. For example, complement contributes to normal brain and embryonic development and to the homeostasis of lipid metabolism. However, the complement system is subjected to the effective balance between activation-inactivation to maintain complement homeostasis and to prevent self-injury to cells or tissues. When this control is disrupted, serious pathologies eventually develop, such as C3 glomerulopathy, autoimmune conditions and infections. Another heterogeneous group of ultra-rare diseases in which complement abnormalities have been described are the lipodystrophy syndromes. These diseases are characterized by the loss of adipose tissue throughout the entire body or partially. Complement over-activation has been reported in most of the patients with acquired partial lipodystrophy (also called Barraquer-Simons Syndrome) and in some cases of the generalized variety of the disease (Lawrence Syndrome). Even so, the mechanism through which the complement system induces adipose tissue abnormalities remains unclear. This review focuses on describing the link between the complement system and certain forms of lipodystrophy. In addition, we present an overview regarding the clinical presentation, differential diagnosis, classification, and management of patients with lipodystrophy associated with complement abnormalities.

A subset of patients with acquired partial lipodystrophy developing severe metabolic abnormalities

Purpose/Aim of the study: Acquired partial lipodystrophy (APL) is a rare disease characterized by selective loss of adipose tissue. In this study, we aimed to present a subset of patients with APL, who developed severe metabolic abnormalities, from our national lipodystrophy registry.

MATERIALS AND METHODS

Severe metabolic abnormalities were defined as: poorly controlled diabetes (HbA1c above 7% despite treatment with insulin more than 1 unit/kg/day combined with oral antidiabetics), severe hypertriglyceridemia (triglycerides above 500 mg/dL despite treatment with lipid-lowering drugs), episodes of acute pancreatitis, or severe hepatic involvement (biopsy-proven non-alcoholic steatohepatitis (NASH)).

RESULTS

Among 140 patients with all forms of lipodystrophy (28 with APL), we identified 6 APL patients with severe metabolic abnormalities. The geometric mean for age was 37 years (range: 27-50 years; 4 females and 2 males). Five patients had poorly controlled diabetes despite treatment with high-dose insulin combined with oral antidiabetics. Severe hypertriglyceridemia developed in five patients, of those three experienced episodes of acute pancreatitis. Although all six patients had hepatic steatosis at various levels on imaging studies, NASH was proven in two patients on liver biopsy. Our data suggested that APL patients with severe metabolic abnormalities had a more advanced fat loss and longer disease duration.

CONCLUSIONS

We suggest that these patients represent a potential subgroup of APL who may benefit from metreleptin or investigational therapies as standard treatment strategies fail to achieve a good metabolic control.

[Unusual facies and recurrent high triglycerides for more than one year in a girl]

A girl, aged 1 year and 9 months, was found to have hypertriglyceridemia in the neonatal period, with unusual facies and signs of dark skin all over the body, disappearance of subcutaneous adipose, acanthosis nigricans of the neck, excessive and thick hair, empty cheeks, muscle hypertrophy of the extremities, hepatomegaly, and neutrophil deficiency. Whole exome sequencing of monogenic disorder revealed a homozygote mutation in the BSCL2 gene, c.974 (exon 7)_c.975 (exon 7) insG. Her parents were heterozygotes for this locus. The girl was diagnosed with congenital generalized lipodystrophy (CGL), but the association between CGL and neutrophil deficiency remained unclear. Triglyceride was maintained at a normal level after the treatment with a low-fat and high-carbohydrate diet, and there were no obvious changes in signs. CGL is a rare autosomal recessive systemic disease manifested as disappearance of systemic subcutaneous adipose, muscle hypertrophy of the extremities, and metabolic disorders in the neonatal period, such as high triglycerides, hyperinsulinemia, and hyperglycemia. About 95% of CGL cases are caused by mutations in the AGPAT2 or BSCL2 gene.

Phenotypic and Genetic Characteristics of Lipodystrophy: Pathophysiology, Metabolic Abnormalities, and Comorbidities

PURPOSE OF REVIEW

This article focuses on recent progress in understanding the genetics of lipodystrophy syndromes, the pathophysiology of severe metabolic abnormalities caused by these syndromes, and causes of severe morbidity and a possible signal of increased mortality associated with lipodystrophy. An updated classification scheme is also presented.

RECENT FINDINGS

Lipodystrophy encompasses a group of heterogeneous rare diseases characterized by generalized or partial lack of adipose tissue and associated metabolic abnormalities including altered lipid metabolism and insulin resistance. Recent advances in the field have led to the discovery of new genes associated with lipodystrophy and have also improved our understanding of adipose biology, including differentiation, lipid droplet assembly, and metabolism. Several registries have documented the natural history of the disease and the serious comorbidities that patients with lipodystrophy face. There is also evolving evidence for increased mortality rates associated with lipodystrophy. Lipodystrophy syndromes represent a challenging cluster of diseases that lead to severe insulin resistance, a myriad of metabolic abnormalities, and serious morbidity. The understanding of these syndromes is evolving in parallel with the identification of novel disease-causing mechanisms.

A new type of familial partial lipodystrophy: distinctive fat distribution and proteinuria

PURPOSE

To describe an interesting subtype of familial partial lipodystrophy (FPLD).

METHODS

The phenotype of this distinctive FPLD subtype was studied in three Turkish female siblings.

RESULTS

Mutation testing was negative for the genes associated with lipodystrophy syndromes. In MRI studies, fat loss was prominent in the posterior aspects of the proximal lower limbs, whilst some fat was preserved in the anterior, medial and lateral aspects. Remarkably, fat tissue was preserved in the distal part of the limbs. Local fat accumulation was observed in the mons pubis area. Asymmetrical fat loss was also remarkable in the upper extremities. All three patients had severe insulin resistance associated with diabetes mellitus, acanthosis nigricans, hypertriglyceridemia and hepatic steatosis. Abnormal amounts of proteinuria were detected in all three subjects. Renal biopsy showed mild tubular atrophy, interstitial fibrosis, irregular thickening and wrinkling of glomerular basal membranes, small areas of segmental sclerosis and pedicel effacement.

CONCLUSIONS

We reported a form of FPLD characterized by a striking pattern of highly selective partial fat loss and proteinuria.

Update on Therapeutic Options in Lipodystrophy

PURPOSE OF REVIEW

The purpose of this review is to summarize the therapeutic approach for lipodystrophy syndromes with conventional treatment options and metreleptin therapy in detail and to point out the current investigational treatments in development.

RECENT FINDINGS

The observation of leptin deficiency in patients with lipodystrophy and the potential of leptin replacement to rescue metabolic abnormalities in animal models of lipodystrophy were followed by the first clinical study of leptin therapy in patients with severe lipodystrophy. This and several other long-term studies demonstrated important benefits of recombinant human leptin (metreleptin) to treat metabolic abnormalities of lipodystrophy. These studies ultimately led to the recent FDA approval of metreleptin for the treatment of generalized lipodystrophy and EMA approval for both generalized and partial lipodystrophy. Additional research efforts in progress focus on novel treatment options, predominantly for patients with partial lipodystrophy. Current treatment of generalized lipodystrophy includes metreleptin replacement as an adjunct to diet and standard treatment approach for metabolic consequences of lipodystrophy. Beyond metreleptin, a number of different compounds and treatment modalities are being studied for the treatment of partial lipodystrophy.

Paediatric fatty liver disease (PeFLD): All is not NAFLD - Pathophysiological insights and approach to management

The recognition of a pattern of steatotic liver injury where histology mimicked alcoholic liver disease, but alcohol consumption was denied, led to the identification of non-alcoholic fatty liver disease (NAFLD). Non-alcoholic fatty liver disease has since become the most common chronic liver disease in adults owing to the global epidemic of obesity. However, in paediatrics, the term NAFLD seems incongruous: alcohol consumption is largely not a factor and inherited metabolic disorders can mimic or co-exist with a diagnosis of NAFLD. The term paediatric fatty liver disease may be more appropriate. In this article, we summarise the known causes of steatosis in children according to their typical, clinical presentation: i) acute liver failure; ii) neonatal or infantile jaundice; iii) hepatomegaly, splenomegaly or hepatosplenomegaly; iv) developmental delay/psychomotor retardation and perhaps most commonly; v) the asymptomatic child with incidental discovery of abnormal liver enzymes. We offer this model as a means to provide pathophysiological insights and an approach to management of the ever more complex subject of fatty liver.

Lipid Oxidation Assessed by Indirect Calorimetry Predicts Metabolic Syndrome and Type 2 Diabetes

Purpose: Diabetes has been linked to an impaired ability to oxidize fatty acids. Fat oxidation can be assessed clinically by a respiratory quotient measurement during fasting. We hypothesized that a respiratory quotient might predict metabolic syndrome and type 2 diabetes onset. Methods: In this longitudinal study we used an existing database of 233 individuals who had complete nutritional and biochemical data at baseline and after 12-month follow-up. All participants underwent an indirect calorimetry to measure the respiratory quotient. We excluded participants with diabetes, metabolic syndrome, chronic diseases, and those who had changed food habits in the previous 3 months. Only 88 subjects met the inclusion criteria. Results: Two individuals developed type 2 diabetes and 10 metabolic syndrome after 1 year. Participants in the high respiratory quotient group (>0.91) had a higher incidence of metabolic syndrome/diabetes than those in the low quotient group (25 vs. 8% p = 0.04). In this group, mean basal respiratory quotient was 0.97 ± 0.04. In the high respiratory quotient group, Kaplan-Meier curves showed a greater probability of having metabolic syndrome/diabetes than those in the low respiratoryquotient group (log Rank χ²-test = 8.44; p = 0.004). A multivariable Cox proportional hazards model demonstrated that energy expenditure and weight increase did not predict metabolic syndrome/diabetes [HR (95% CI) = 1 (0.996-1.005), p = 0.86 and 3.9 (0.407-38.061), p = 0.23, respectively). Conclusions: A greater probability of metabolic syndrome/diabetes was found in individuals with a basal respiratory quotient of >0.91 than in those with a respiratoryquotient of ≤ 0.91 after 1 year. In the short-term anthropometric measurements and their variation overtime were not correlated with metabolic syndrome/diabetes.

Endoplasmic reticulum stress activation in adipose tissue induces metabolic syndrome in individuals with familial partial lipodystrophy of the Dunnigan type

BACKGROUND

Familial partial lipodystrophy of the Dunnigan type is one of the most common inherited lipodystrophies variables. These individuals have important metabolic disorders that cause predisposition to various diseases. In this study we aimed to demonstrate the relation between the metabolic abnormalities, inflammatory profile and the expression of genes involved in the activation of the endoplasmic reticulum stress (ERS) in subjects with FPLD.

METHODS

We evaluated 14 female FPLD patients and compared with 13 female healthy individuals. The subjects were paired with their respective BMI and age and categorized into two groups: Familial partial lipodystrophy of the Dunnigan type (FPLD) and control. Patients were fasted for 12 h before blood collection for measurement of HbA1c, glucose, insulin, lipids and inflammatory markers. Subcutâneous adipose tissue was collected by puncture aspiration of submental region during ambulatorial surgical aesthetic procedure.

RESULTS

We demonstrate that patients with FPLD show increased HbA1c (p < 0.01), fasting glucose (p < 0.002) and triglycerides (p < 0.005) while HDL/cholesterol (p < 0.001) was lower when compared to healthy individuals. We found that 64.2% FPLD patients had metabolic syndrome according to International Diabetes Federation definition. We also observe increased AUC of glucose (p < 0.001) and insulin during oGTT, featuring a frame of hyperglycemia and hyperinsulinemia, suggesting insulin resistance. Also we found hyperactivation of several genes responsible for ERS such as ATF-4 (p < 0.01), ATF-6 (p < 0.01), EIF2α3K (p < 0.005), CCT4 (p < 0.001), CHOP (p < 0.01), CALR (p < 0.001) and CANX (p < 0.005), that corroborate the idea that diabetes mellitus and metabolic syndrome are associated with direct damage to the endoplasmic reticulum homeostasis. Ultimately, we note that individuals with lipodystrophy have an increase in serum interleukins, keys of the inflammatory process, as IL-1β, TNF-α and IL-6 (p < 0.05 all), compared with healthy individuals, which can be the trigger to insulin resistance in this population.

CONCLUSION

Individuals with FPLD besides having typical dysfunctions of metabolic syndrome, show a hyperactivation of ERS associated with increased systemic inflammatory profile, which together may explain the complex clinical aspect of this diseases.Trial registration HCRP no 6711/2012.

Factors regulating subcutaneous adipose tissue storage, fibrosis, and inflammation may underlie low fatty acid mobilization in insulin-sensitive obese adults

Although the rate of fatty acid release from adipose tissue into the systemic circulation is very high in most obese adults, some obese adults maintain relatively low rates of fatty acid release, which helps protect them against the development of systemic insulin resistance. The primary aim of this study was to identify factors in adipose tissue that may underlie low vs. high rates of fatty acid mobilization in a relatively homogeneous cohort of obese adults. We measured systemic fatty acid rate of appearance (FA Ra) via ¹³C-palmitate isotope dilution, and we obtained subcutaneous abdominal adipose tissue samples from 30 obese adults (BMI: 38 ± 1 kg/m², age: 30 ± 2 yr) after an overnight fast. We then measured insulin sensitivity using a hyperinsulinemic-euglycemic clamp. Confirming our previous work, insulin sensitivity was inversely proportional to FA Ra (R² = 0.50; P < 0.001). Immunoblot analysis of subcutaneous adipose tissue samples revealed that, compared with obese adults with high FA Ra, those with low FA Ra had lower markers of lipase activation and higher abundance of glycerol-3-phosphate acyltransferase, which is a primary enzyme for fatty acid esterification. Microarray and pathway analysis provided evidence of lower fibrosis and lower SAPK/JNK pathway activation in obese adults with low FA Ra compared with those with high FA Ra. Our findings suggest that alterations in factors regulating triglyceride storage in adipose tissue, along with lower fibrosis and inflammatory pathway activation, may underlie maintenance of a relatively low FA Ra in obesity, which may help protect against the development of insulin resistance.

Clinical spectra of neuromuscular manifestations in patients with lipodystrophy: A multicenter study

Lipodystrophy is a heterogeneous group of disorders characterized by loss of adipose tissue. Here, we report on clinical spectra of neuromuscular manifestations of Turkish patients with lipodystrophy. Seventy-four patients with lipodystrophy and 20 healthy controls were included. Peripheral sensorimotor neuropathy was a common finding (67.4%) in lipodystrophic patients with diabetes. Neuropathic foot ulcers were observed in 4 patients. Drop foot developed in 1 patient with congenital generalized lipodystrophy type 1. Muscle symptoms and hypertrophy were consistent findings in congenital generalized lipodystrophy (21/21) and familial partial lipodystrophy (25/34); on the other hand, overt myopathy with elevated creatine kinase activity was a distinctive characteristic of congenital generalized lipodystrophy type 4. Muscle biopsies revealed myopathic changes at different levels. Accumulation of triglycerides was observed which contributes to insulin resistance. All patients with congenital generalized lipodystrophy suffered from tight Achilles tendons at various levels. Scoliosis was observed in congenital generalized lipodystrophy type 4 (2/2) and familial partial lipodystrophy type 2 (2/17). Atlantoaxial instability was unique to congenital generalized lipodystrophy type 4 (2/2). Bone cysts were detected in congenital generalized lipodystrophy type 1 (7/10) and congenital generalized lipodystrophy type 2 (2/8). Our study suggests that lipodystrophies are associated with a wide spectrum of neuromuscular abnormalities.

Improvement of metabolic disorders by an EP2 receptor agonist via restoration of the subcutaneous adipose tissue in pulmonary emphysema

Chronic obstructive pulmonary disease (COPD) is often associated with co-morbidities. Metabolic disorders like hyperlipidemia and diabetes occur also in underweight COPD patients, although the mechanism is uncertain. Subcutaneous adipose tissue (SAT) plays an important role in energy homeostasis, since restricted capacity to increase fat cell number with increase in fat cell size occurring instead, is associated with lipotoxicity and metabolic disorders. The aim of this study is to show the protective role of SAT for the metabolic disorders in pulmonary emphysema of a murine model. We found ectopic fat accumulation and impaired glucose homeostasis with wasting of SAT in a murine model of elastase-induced pulmonary emphysema (EIE mice) reared on a high-fat diet. ONO-AE1-259, a selective E-prostanoid (EP) 2 receptor agonist, improved angiogenesis and subsequently adipogenesis, and finally improved ectopic fat accumulation and glucose homeostasis with restoration of the capacity for storage of surplus energy in SAT. These results suggest that metabolic disorders like hyperlipidemia and diabetes occured in underweight COPD is partially due to the less capacity for storage of surplus energy in SAT, though the precise mechanism is uncertained. Our data pave the way for the development of therapeutic interventions for metabolic disorders in emphysema patients, e.g., use of pro-angiogenic agents targeting the capacity for storage of surplus energy in the subcutaneous adipose tissue.

Partial lipodystrophy in patients who have undergone hematopoietic stem cell transplantation during childhood: an institutional cross-sectional survey

Partial lipodystrophy (PD), a condition similar to metabolic syndrome without obesity, is one of the late complications of hematopoietic stem cell transplantation (HSCT) performed during childhood. We aimed to investigate the prevalence and risk factors of PD. A cross-sectional survey was performed in a children’s hospital, targeting patients treated for a malignancy or hematological disorder, and who were disease-free for > 24 mo. PD was defined as gluteal lipoatrophy and lipohypertrophy of the cheeks or neck associated with diabetes and/or fatty liver disease. In total, 65 patients were enrolled. Six patients (9.2%) were judged to have PD, all of whom had received 10–14 Gy total body irradiation. Compared with the patients without PD, patients with PD were older at investigation (P < 0.01), had a longer elapsed time following HSCT (P < 0.01), had more frequent disease recurrence (P < 0.05), and were more likely to have undergone multiple HSCT (P < 0.05). In addition, they had higher blood pressure and showed higher levels of low-density lipoprotein-cholesterol and triglycerides, whereas their adiponectin levels were significantly lower. In conclusion, a large number of patients developed PD following HSCT, with unfavorable metabolic profiles at a later age, especially when they experienced a complex disease course.

Peroxisome proliferator activated receptor gamma 2 modulates late pregnancy homeostatic metabolic adaptations

Pregnancy requires the adaptation of maternal energy metabolism including expansion and functional modifications of adipose tissue. Insulin resistance (IR), predominantly during late gestation, is a physiological metabolic adaptation that serves to support the metabolic demands of fetal growth. The molecular mechanisms underlying these adaptations are not fully understood and may contribute to gestational diabetes mellitus. Peroxisome proliferator-activated receptor gamma (PPARγ) controls adipogenesis, glucose and lipid metabolism and insulin sensitivity. The PPARγ2 isoform is mainly expressed in adipocytes and is thus likely to contribute to adipose tissue adaptation during late pregnancy. In the present study, we investigated the contribution of PPARγ2 to the metabolic adaptations occurring during the late phase of pregnancy in the context of IR. Using a model of late pregnancy in PPARγ2 knockout (KO) mice, we found that deletion of PPARγ2 exacerbated IR in association with lower serum adiponectin levels, increased body weight and enhanced lipid accumulation in liver. Lack of PPARγ2 provoked changes in the distribution of fat mass and preferentially prevented the expansion of the perigonadal depot while at the same time exacerbating inflammation. PPARγ2KO pregnant mice presented adipose tissue depot-dependent decreased expression of genes involved in lipid metabolism. Collectively, these data indicate that PPARγ2 is essential to promote healthy adipose tissue expansion and immune and metabolic functionality during pregnancy, contributing to the physiological adaptations that lead gestation to term.

Partial lipodystrophy of the limbs in a diabetes clinic setting

OBJECTIVE

Partial lipodystrophy of the limbs (PLL) is a newly described form of lipodystrophy that is characterized by symmetrical distal lipoatrophy of the limbs and insulin resistant diabetes.

RESEARCH DESIGN AND METHODS

In this study, we prospectively screened our patients with type 2 diabetes for the presence of PLL phenotype. Metabolic parameters of PLL patients were compared to those with type 2 diabetes who applied to our diabetes clinic during the same period of time.

RESULTS

Between Sep 2013 and Mar 2015, 2020 patients with type 2 diabetes were evaluated for the presence of PLL. PLL was confirmed in 16 patients. The prevalence of PLL was calculated as 0.79% in our diabetes clinic. The most common phenotypic presentations were loss of subcutaneous fat in the forearms, calves and thighs, and loss of fat in forearms and calves. Patients with PLL had poor metabolic control and marked insulin resistance compared to subjects with type 2 diabetes. Diabetes had been diagnosed at a younger age in patients with PLL. Patients with PLL also had more atherogenic lipid profiles.

CONCLUSIONS

Our data suggests that PLL is a relatively common form of lipodystrophy in diabetes clinics, which is associated with poor metabolic control and marked insulin resistance. The recognition of PLL in patients with type 2 diabetes can help better clinical management by alerting the physician to these associated co-morbidities.

Overnutrition, ectopic lipid and the metabolic syndrome

The metabolic syndrome is a constellation of metabolic risk factors including atherogenic dyslipidemia (elevated serum triglycerides, reduced high-density lipoprotein (HDL) cholesterol), elevated blood pressure, dysglycemia (insulin resistance and elevated serum glucose), a pro-inflammatory state, and a prothrombotic state. Most persons with metabolic syndrome are obese, and usually have abdominal obesity. Generally, obesity is a reflection of overnutrition. A current view is that when adipose tissue fails to store all excess nutrients as triglyceride, lipid begins to accumulate in various tissues (eg, muscle, liver, pancreas, and heart). This accumulation is called ectopic lipid. Various mechanisms have been proposed whereby ectopic lipid is detrimental in different tissues; these derangements induce metabolic risk factors. The foundation of the metabolic syndrome thus appears to be overnutrition, that is, more nutrient intake than can be safely disposed by lipid oxidation. Excess dietary carbohydrate also induces ectopic lipid. Of interest, less than half of obese individuals develop metabolic syndrome. Through various mechanisms they adapt to overnutrition so as to minimize lipid overload in tissues, and consequently, prevent the syndrome.

Metreleptin and generalized lipodystrophy and evolving therapeutic perspectives

INTRODUCTION

Metreleptin was recently approved by the Food and Drug Administration for the treatment of generalized lipodystrophy, a condition characterized by leptin deficiency. Its efficacy as hormone replacement therapy suggests broader applications in diseases also characterized by leptin abnormalities, such as familial partial lipodystrophy (FPLD), non-alcoholic fatty liver disease (NAFLD), and common obesity. Metreleptin, in conjunction with other pharmacologic interventions, has the potential to address one of the most widespread epidemics of our time, obesity.

AREAS COVERED

This review covers the physiology of leptin, the pharmacologic properties of recombinant methionyl human leptin (R-metHu-Leptin, metreleptin), evidence for metreleptin's efficacy in the treatment of generalized lipodystrophy from both completed and ongoing clinical trials, safety concerns, and future directions in metreleptin research.

EXPERT OPINION

Metreleptin's approval for generalized lipodystrophy is the first step in defining and expanding its role to other metabolic diseases. Clinical trials are underway to delineate its efficacy in FPLD, human immunodeficiency virus/highly active anti-retroviral therapy-associated acquired lipodystrophy (HAL), and NAFLD. Additionally, there is growing data that support a therapeutic role in obesity. One of the barriers to development, however, is metreleptin's safety and immunogenicity. Further advances in biologic compatibility are required before metreleptin can be approved for additional indications.

The CardioMetabolic Health Alliance: Working Toward a New Care Model for the Metabolic Syndrome

The Cardiometabolic Think Tank was convened on June 20, 2014, in Washington, DC, as a "call to action" activity focused on defining new patient care models and approaches to address contemporary issues of cardiometabolic risk and disease. Individual experts representing >20 professional organizations participated in this roundtable discussion. The Think Tank consensus was that the metabolic syndrome (MetS) is a complex pathophysiological state comprised of a cluster of clinically measured and typically unmeasured risk factors, is progressive in its course, and is associated with serious and extensive comorbidity, but tends to be clinically under-recognized. The ideal patient care model for MetS must accurately identify those at risk before MetS develops and must recognize subtypes and stages of MetS to more effectively direct prevention and therapies. This new MetS care model introduces both affirmed and emerging concepts that will require consensus development, validation, and optimization in the future.

Adipose tissue and metabolic syndrome: too much, too little or neither

Obesity is strongly associated with metabolic syndrome. Recent research suggests that excess adipose tissue plays an important role in development of the syndrome. On the other hand, persons with a deficiency of adipose tissue (e.g. lipodystrophy) also manifest the metabolic syndrome. In some animal models, expansion of adipose tissue pools mitigates adverse metabolic components (e.g. insulin resistance, hyperglycaemia and dyslipidemia). Hence, there are conflicting data as to whether adipose tissue worsens the metabolic syndrome or protects against it. This conflict may relate partly to locations of adipose tissue pools. For instance, lower body adipose tissue may be protective whereas upper body adipose tissue may promote the syndrome. One view holds that in either case, the accumulation of ectopic fat in muscle and liver is the driving factor underlying the syndrome. If so, there may be some link between adipose tissue fat and ectopic fat. But the mechanisms underlying this connection are not clear. A stronger association appears to exist between excessive caloric intake and ectopic fat accumulation. Adipose tissue may act as a buffer to reduce the impact of excess energy consumption by fat storage; but once a constant weight has been achieved, it is unclear whether adipose tissue influences levels of ectopic fat. Another mechanism whereby adipose tissue could worsen the metabolic syndrome is through release of adipokines. This is an intriguing mechanism, but the impact of adipokines on metabolic syndrome risk factors is uncertain. Thus, many potential connections between adipose tissue and metabolic syndrome remain to unravelled.

Acquired partial lipodystrophy is associated with increased risk for developing metabolic abnormalities

OBJECTIVE

Acquired partial lipodystrophy (APL) is a rare disorder characterized by progressive selective fat loss. In previous studies, metabolic abnormalities were reported to be relatively rare in APL, whilst they were quite common in other types of lipodystrophy syndromes.

METHODS

In this nationwide cohort study, we evaluated 21 Turkish patients with APL who were enrolled in a prospective follow-up protocol. Subjects were investigated for metabolic abnormalities. Fat distribution was assessed by whole body MRI. Hepatic steatosis was evaluated by ultrasound, MRI and MR spectroscopy. Patients with diabetes underwent a mix meal stimulated C-peptide/insulin test to investigate pancreatic beta cell functions. Leptin and adiponectin levels were measured.

RESULTS

Fifteen individuals (71.4%) had at least one metabolic abnormality. Six patients (28.6%) had diabetes, 12 (57.1%) hypertrigylceridemia, 10 (47.6%) low HDL cholesterol, and 11 (52.4%) hepatic steatosis. Steatohepatitis was further confirmed in 2 patients with liver biopsy. Anti-GAD was negative in all APL patients with diabetes. APL patients with diabetes had lower leptin and adiponectin levels compared to patients with type 2 diabetes and healthy controls. However, contrary to what we observed in patients with congenital generalized lipodystrophy (CGL), we did not detect consistently very low leptin levels in APL patients. The mix meal test suggested that APL patients with diabetes had a significant amount of functional pancreatic beta cells, and their diabetes was apparently associated with insulin resistance.

CONCLUSIONS

Our results show that APL is associated with increased risk for developing metabolic abnormalities. We suggest that close long-term follow-up is required to identify and manage metabolic abnormalities in APL.

Insulin and GH-IGF-I axis: endocrine pacer or endocrine disruptor?

Growth hormone/insulin-like growth factor (IGF) axis may play a role in maintaining glucose homeostasis in synergism with insulin. IGF-1 can directly stimulate glucose transport into the muscle through either IGF-1 or insulin/IGF-1 hybrid receptors. In severely decompensated diabetes including diabetic ketoacidosis, plasma levels of IGF-1 are low and insulin delivery into the portal system is required to normalize IGF-1 synthesis and bioavailability. Normalization of serum IGF-1 correlated with the improvement of glucose homeostasis during insulin therapy providing evidence for the use of IGF-1 as biomarker of metabolic control in diabetes. Taking apart the inherent mitogenic discussion, diabetes treatment using insulins with high affinity for the IGF-1 receptor may act as an endocrine pacer exerting a cardioprotective effect by restoring the right level of IGF-1 in bloodstream and target tissues, whereas insulins with low affinity for the IGF-1 receptor may lack this positive effect. An excessive and indirect stimulation of IGF-1 receptor due to sustained and chronic hyperinsulinemia over the therapeutic level required to overtake acute/chronic insulin resistance may act as endocrine disruptor as it may possibly increase the cardiovascular risk in the short and medium term and mitogenic/proliferative action in the long term. In conclusion, normal IGF-1 may be hypothesized to be a good marker of appropriate insulin treatment of the subject with diabetes and may integrate and make more robust the message coming from HbA1c in terms of prediction of cardiovascular risk.

Familial partial lipodystrophy, Dunnigan variety - challenges for patient care during pregnancy: a case report

Background

Familial partial lipodystrophy, Dunnigan variety, is a recognised autosomal dominant disorder which is caused by heterozygous missense mutations in the lamin A/C gene. Dunnigan lipodystrophy is characterised by a variable loss of fat from the extremities and trunk, as well as an excess of subcutaneous fat in the chin and supraclavicular area. The associated metabolic abnormalities include: insulin resistance, diabetes, dyslipidaemia and low leptin levels.

Case presentation

The authors studied the case of a 24-year-old caucasian pregnant woman, with a past medical history of acute pancreatitis, combined dyslipidaemia and diabetes mellitus. At 7 weeks of pregnancy she was referred to the outpatient endocrinology and obstetrics clinic for diabetes care. A physical examination revealed that she presented a loss of fat from the extremities and trunk and also had an excess of subcutaneous fat in the chin. Triglyceride levels were persistently high, and glycaemic control was only achieved through the administration of high doses of insulin (1.8 U/Kg/day). Dunnigan lipodystrophy was suspected and thus a genetic study was requested, which revealed the presence of c.1444C > T (p.Arg482Trp) heterozygote mutation in the lamin A/C gene.

Conclusion

This case is used to illustrate the importance of being able to recognise the clinical signs of this rare lipodystrophic syndrome, which may cause potentially severe consequences, and also the difficulties in treating it during pregnancy.

Leptin in congenital and HIV-associated lipodystrophy

Leptin is a hormone secreted by adipocytes that regulates energy metabolism via peripheral action on glucose synthesis and utilization as well as through central regulation of food intake. Patients with decreased amounts of fat in their adipose tissue (lipoatrophy) will have low leptin levels, and hypoleptinemic states have been associated with a variety of metabolic dysfunctions. Pronounced complications of insulin resistance, dyslipidemia and fatty liver are observed in patients suffering from congenital or acquired generalized lipodystrophy while somewhat less pronounced abnormalities are associated with human immunodeficiency virus (HIV) and the use of highly active antiretroviral therapy, the so-called HIV-associated lipodystrophy. Previous uncontrolled open-label studies have demonstrated that physiological doses of leptin repletion have corrected many of the metabolic derangements observed in subjects with rare fat maldistribution syndromes such as generalized lipodystrophy. In the much more commonly encountered HIV-associated lipodystrophy, leptin replacement has been shown to decrease central fat mass and to improve insulin sensitivity, dyslipidemia, and glucose levels. The United States Food and Drug Administration has recently granted approval for recombinant leptin therapy for congenital and acquired generalized lipodystrophy, however large, well-designed, placebo-controlled studies are needed to assess long-term efficacy, safety and adverse effects of leptin replacement. In this review, we present the role of leptin in the metabolic complications of congenital and acquired lipodystrophy and discuss current and emerging clinical therapeutic uses of leptin in humans with lipodystrophy.

Adipose tissue mitochondrial dysfunction triggers a lipodystrophic syndrome with insulin resistance, hepatosteatosis, and cardiovascular complications

Mitochondrial dysfunction in adipose tissue occurs in obesity, type 2 diabetes, and some forms of lipodystrophy, but whether this dysfunction contributes to or is the result of these disorders is unknown. To investigate the physiological consequences of severe mitochondrial impairment in adipose tissue, we generated mice deficient in mitochondrial transcription factor A (TFAM) in adipocytes by using mice carrying adiponectin-Cre and TFAM floxed alleles. These adiponectin TFAM-knockout (adipo-TFAM-KO) mice had a 75-81% reduction in TFAM in the subcutaneous and intra-abdominal white adipose tissue (WAT) and interscapular brown adipose tissue (BAT), causing decreased expression and enzymatic activity of proteins in complexes I, III, and IV of the electron transport chain (ETC). This mitochondrial dysfunction led to adipocyte death and inflammation in WAT and a whitening of BAT. As a result, adipo-TFAM-KO mice were resistant to weight gain, but exhibited insulin resistance on both normal chow and high-fat diets. These lipodystrophic mice also developed hypertension, cardiac hypertrophy, and cardiac dysfunction. Thus, isolated mitochondrial dysfunction in adipose tissue can lead a syndrome of lipodystrophy with metabolic syndrome and cardiovascular complications.

Barraquer-Simons syndrome: a rare clinical entity

The Barraquer-Simons syndrome or acquired parital lipodystrophy is a rare form of partial lipodystrophy characterized by gradual onset of bilaterally symmetrical subcutaneous fat loss from the face, neck, upper extremities, thorax, and abdomen but sparing the lower extremities. The patients gradually loose their subcutaneous fat in clearly demarcated, generally symmetric areas of the body over several years. Nephropathy, myopathy, deafness, epilepsy, and intellectual disability have also been described. Although the etiology is unknown, heterozygous mutations in the gene encoding one of the nuclear lamina proteins, lamin B2, have been reported in several patients. We here report on a young female patient affected by Barraquer-Simons syndrome, without accompanying renal or central nervous system involvement in whom DNA sequencing did not reveal any mutations in the genes LMNB2, LMNA, PPARG, AGPAT2, BSCL2, CAV1, PTRF, PLIN1, and CIDEC.

Post-liver transplant leptin results in resolution of severe recurrence of lipodystrophy-associated nonalcoholic steatohepatitis

We describe the first case of a patient undergoing orthoptic liver transplantation for acquired generalized lipodystrophy-related nonalcoholic steatohepatitis who developed severe recurrence of nonalcoholic fatty liver disease in the first few months posttransplant but responded rapidly to the administration of exogenous leptin. The beneficial effects of therapy were supported by histology along with magnetic resonance spectroscopy studies, which demonstrated that leptin therapy greatly reduced fat deposition in the liver. Leptin therapy may have a role to play in preventing patients with lipodystrophy developing end-stage liver disease or in rescuing such patients who develop disease recurrence postliver transplantation.

[Bezafibrate in an infant with congenital generalized lipodystrophy and severe hypertriglyceridemia]

Congenital generalized lipodystrophy (CGL) with severe hypertriglyceridemia in a children less than 1 year of age is associated with worse metabolic risk. We used data from patient records, as well as extensive literature research to write the manuscript. We report the case of an infant with typical phenotype of CGL and hypertriglyceridemia of 1,360 mg/dL who was treated with bezafibrate at a dose of 30 to 60 mg/day from age 11 months to 5.5 years old, with a measurement of nadir of triglycerides of 55 mg/dL. Clinical evolution and clinical laboratory tests before and after bezafibrate were carried out over 5 years and 6 months. Phenotype was classified as CGL type 2. Despite the efficient control of hypertriglyceridemia and absence of development of diabetes mellitus, the use of bezafibrate did not prevent the onset of hepatic steatosis during evolution. Hypolipidemic therapy with bezafibrate proved effective in maintaining the levels of triglycerides, cholesterol and its fractions at normal levels, and its use was not correlated with severe side effects during the described period.

Lipoatrophy and severe metabolic disturbance in mice with fat-specific deletion of PPARγ

Adipose tissue is an important metabolic organ, the dysfunction of which is associated with the development of obesity, diabetes mellitus, and cardiovascular disease. The nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) is considered the master regulator of adipocyte differentiation and function. Although its cell-autonomous role in adipogenesis has been clearly demonstrated in cell culture, previous fat-specific knockouts of the murine PPARγ gene did not demonstrate a dramatic phenotype in vivo. Here, using Adipoq-Cre mice to drive adipose-specific recombination, we report a unique fat-specific PPARγ knockout (PPARγ FKO) mouse model with almost no visible brown and white adipose tissue at age 3 mo. As a consequence, PPARγ FKO mice had hugely enlarged pancreatic islets, massive fatty livers, and dramatically elevated levels of blood glucose and serum insulin accompanied by extreme insulin resistance. PPARγ FKO mice also exhibited delayed hair coat formation associated with absence of dermal fat, disrupted mammary gland development with loss of mammary fat pads, and high bone mass with loss of bone marrow fat, indicating the critical roles of adipose PPARγ in these tissues. Together, our data reveal the necessity of fat PPARγ in adipose formation, whole-body metabolic homeostasis, and normal development of fat-containing tissues.

Exploring the pathophysiology behind the more common genetic and acquired lipodystrophies

Lipodystrophies are an immense group of genetic or acquired metabolic disorders that are characterized by varying degrees of body fat loss and in some instances localized accumulation of subcutaneous fat. Lipodystrophies are often tightly linked with profound metabolic complications; this strong bond emphasizes and reinforces the significance of adipose tissue as a dynamic endocrine organ. The extent of fat loss determines the severity of associated metabolic complications such as diabetes mellitus, hypertriglyceridemia and hepatic steatosis. The lipodystrophies can be divided into generalized, partial or local, depending on the degree and locality of the observable fat loss; moreover, the generalized and partial divisions can be partitioned further into inherited or acquired forms. The major genetic factors in the generalized forms of the lipodystrophies, particularly Congenital generalized lipodystrophy (CGL)-Berardinelli-Seip syndrome, are the AGPAT2, BSCL2, caveolin 1 (CAV1) and polymerase-I-and-transcriptrelease factor (PTRF) genes. In the acquired forms, genes such as LMNA, PPARG, CIDEC (cell-death-inducing DNA fragmentation factor a-like effector c) and PLIN1 are heavily involved in familial partial lipodystrophy (FPLD) type 2 (also known as the Dunnigan-Variety) and WRN along with RECQL5 in Werner Syndrome (WS). Autoimmune causes are particularly noted in acquired partial lipodystrophy (APL)-Barraquer-Simons syndrome and in AGL-Lawrence syndrome; panniculitis has been shown to have a substantial role in the former as well as in other forms of localized lipodystrophies. Patients with human immunodeficiency virus (HIV) exposed to protease inhibitors, nucleoside reverse transcriptase inhibitors (NRTIs) (for example, zidovudine and stavudine) or non-nucleoside reverse transcriptase inhibitors (NNRTIs) (for example, efavirenz) while undergoing Highly Active Antiretroviral Therapy (HAART) have led to the current most-prevalent form of the lipodystrophies: lipodystrophy in HIV-infected patients (LD-HIV) and HAART-associated lipodystrophy syndrome (HALS).