Efficacy and safety of pioglitazone in treatment of a patient with an atypical partial lipodystrophy syndrome

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.

Approach to the Patient With Lipodystrophy

Lipodystrophy constitutes a spectrum of diseases characterized by a generalized or partial absence of adipose tissue. Underscoring the role of healthy fat in maintenance of metabolic homeostasis, fat deficiency in lipodystrophy typically leads to profound metabolic disturbances including insulin resistance, hypertriglyceridemia, and ectopic fat accumulation. While rare, recent genetic studies indicate that lipodystrophy is more prevalent than has been previously thought, suggesting considerable underdiagnosis in clinical practice. In this article, we provide an overview of the etiology and management of generalized and partial lipodystrophy disorders. We bring together the latest scientific evidence and clinical guidelines and expose key gaps in knowledge. Through improved recognition of the lipodystrophy disorders, patients (and their affected family members) can be appropriately screened for cardiometabolic, noncardiometabolic, and syndromic abnormalities and undergo treatment with targeted interventions. Notably, insights gained through the study of this rare and extreme phenotype can inform our knowledge of more common disorders of adipose tissue overload, including generalized obesity.

Advances in the care of lipodystrophies

PURPOSE OF REVIEW

Lipodystrophies are a group of rare, heterogeneous disorders characterized by a lack or maldistribution of adipose tissue. Treatment focusses on the management of complications, including hypertriglyceridemia, which can be severe. Patients are predisposed to early atherosclerotic cardiovascular disease and acute pancreatitis. This review summarizes the recent advances in the treatment of lipodystrophies, with a particular focus on the treatment of hypertriglyceridemia in familial partial lipodystrophy (FPLD).

RECENT FINDINGS

Treatment of dyslipidemia in FPLD requires management of secondary exacerbating factors, particularly insulin resistance and diabetes, together with modification of atherosclerotic cardiovascular disease risk factors. In addition, specific lipid-lowering therapies are usually needed, starting with statins and fibrates. Leptin therapy improves triglycerides. Several emerging treatments for hypertriglyceridemia include apo C-III antagonists (volanesorsen, AKCEA-APOCIII-LRx and ARO-APOC3) and angiopoietin-like 3 antagonists (evinacumab, vupanorsen and ARO-ANG3); efficacy observed in clinical trials of these agents in nonlipodystrophic patients with severe hypertriglyceridemia suggests that they may also be helpful in lipodystrophy.

SUMMARY

Emerging therapies for dyslipidemia show promise in advancing the care of patients with lipodystrophy. However, these treatments are not yet approved for use in lipodystrophy. Further study of their efficacy and safety in this patient population is needed.

Lipodistrophy: a paradigm for understanding the consequences of "overloading" adipose tissue

Lipodystrophies have been recognized since at least the nineteenth century and, despite their rarity, tended to attract considerable medical attention because of the severity and somewhat paradoxical nature of the associated metabolic disease that so closely mimics that of obesity. Within the last 20 yr most of the monogenic subtypes have been characterized, facilitating family genetic screening and earlier disease detection as well as providing important insights into adipocyte biology and the systemic consequences of impaired adipocyte function. Even more recently, compelling genetic studies have suggested that subtle partial lipodystrophy is likely to be a major factor in prevalent insulin-resistant type 2 diabetes mellitus (T2DM), justifying the longstanding interest in these disorders. This progress has also underpinned novel approaches to treatment that, in at least some patients, can be of considerable therapeutic benefit.

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.

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.

Case of lipoatrophic diabetes induced by juvenile dermatomyositis

Lipodystrophy is a rare condition that is often accompanied by one or more metabolic diseases. Here, we report a case of lipoatrophic diabetes induced by juvenile dermatomyositis. Although pioglitazone was not effective for lowering blood glucose levels, our observation suggested that it improved liver function slightly. The effectiveness of metreleptin for lowering blood glucose levels could not be determined, as we administered it in a short period. Liver biopsy showed burned-out non-alcoholic steatohepatitis. The present results show that the successful treatment of lipoatrophic diabetes induced by juvenile dermatomyositis requires an early diagnosis and therapeutic intervention.

Genetics in endocrinology: genetic forms of severe insulin resistance: what endocrinologists should know

'Insulin resistance' (IR) is a widely used clinical term. It is usually defined as a state characterised by reduced glucose-lowering activity of insulin, but it is also sometimes used as a shorthand label for a clinical syndrome encompassing major pathologies such as type 2 diabetes, polycystic ovary syndrome, fatty liver disease and atherosclerosis. Nevertheless, the precise cellular origins of IR, the causal links among these phenomena and the mechanisms underlying them remain poorly understood or contentious. Prevalent IR usually results from a genetic predisposition interacting with acquired obesity; however, even in some lean individuals, very severe degrees of IR can be observed. It is important to identify these people as they often harbour identifiable single-gene defects and they may benefit from molecular diagnosis, genetic counselling and sometimes tailored therapies. Observation of people with known single-gene defects also offers the opportunity to make inferences about the mechanistic links between IR and common pathologies. Herein, we summarise the currently known monogenic forms of severe IR, with an emphasis on the practical aspects of their recognition, diagnosis and management. In particular, we draw distinctions among the biochemical subphenotypes of IR that arise from primary adipose tissue dysfunction or from primary insulin signalling defects and discuss the implications of this dichotomy for management.

Premature atherosclerosis in a Japanese diabetic patient with atypical familial partial lipodystrophy and hypertriglyceridemia

We herein report a case of premature atherosclerosis in a patient with familial partial lipodystrophy (FPL), diabetes mellitus, hypertension and hypertriglyceridemia. Sequencing of the candidate genes LMNA, PPARG and CAV1 associated with FPL revealed no genetic abnormalities, which indicated the activity of a novel gene in this patient. The patient's son showed milder fat loss and similar fat distribution compared to the proband; however, the son showed no signs of any atherosclerotic disease. Although a cluster of atherogenic risk factors is likely to be the primary causes of atherosclerosis in our patient, other factors, including an unknown gene associated with FPL, the severity of fat loss and gender, might affect the development of atherosclerosis.

Clinical classification and treatment of congenital and acquired lipodystrophy

OBJECTIVE

To review the initial clinical manifestations of congenital and acquired lipodystrophy syndromes, discuss novel classifications associated with genetic mutations, and assess currently available therapeutic options for patients with lipodystrophy.

METHODS

This review is the result of the authors' collective clinical experience and a comprehensive MEDLINE literature search on the English-language literature published between January 1966 and October 2009 on "lipodystrophy." This review focuses primarily on severe dystrophy not related to human immunodeficiency virus (HIV) infection, in light of the additional scope required to cover HIV-related lipodystrophy.

RESULTS

Congenital lipodystrophy syndromes are characterized by a paucity of adipose tissue and classified on the basis of the extent of fat loss and heritability Paradoxically, they are associated with metabolic abnormalities often found in obese patients, including insulin resistance, diabetes, and severe hypertriglyceridemia. Patients with severe forms of lipodystrophy are also deficient in adipokines such as leptin, which may contribute to metabolic abnormalities. The search for molecular defects has revealed a role for genes that affect adipocyte differentiation (for example, peroxisome proliferator-activated receptor gamma), lipid droplet morphology (seipin, caveolin-1), or lipid metabolism (AGPAT2). Others (lamin A/C) are known to be associated with completely different diseases. There are also acquired forms of lipodystrophy that are thought to occur primarily attributable to autoimmune mechanisms. Recently, recombinant leptin has emerged as a useful therapy.

CONCLUSION

Lipodystrophy syndromes have advanced our understanding of the physiologic role of adipose tissue and allowed identification of key molecular mechanisms involved in adipocyte differentiation. Novel therapeutic strategies are being developed on the basis of the pathophysiologic aspects of these syndromes.

Clinical characteristics and efficacy of pioglitazone in a Japanese diabetic patient with an unusual type of familial partial lipodystrophy

This report describes a 46-year-old Japanese diabetic woman with an unusual type of familial partial lipodystrophy. She has marked loss of subcutaneous fat in her lower limbs and buttocks, with sparing of the face, neck, upper limbs, and trunk. This distribution of fat atrophy appears to be rare in comparison with previous reports. Sequencing of candidate genes LMNA, PPARG, AKT2, caveolin-1, as well as the PPARG4 promoter gene, which are known to be associated with familial partial lipodystrophy, revealed no genetic abnormalities, suggesting that this case may involve a novel gene. Pioglitazone was markedly effective in glycemic control in this case. Her diabetes remained uncontrolled despite a total daily dose of insulin of 30 U and combined treatment with 10 mg of glibenclamide and 0.6 mg of voglibose. We therefore attempted combined treatment with 30 mg of pioglitazone and 30 U/d insulin injection. The hemoglobin A(1c) level was reduced from 11.2% to 6.1% after 6 months of treatment and has since remained stable. Her body weight increased from 62.0 to 71.0 kg after 12 months of treatment, suggesting that weight gain may result from synergism between thiazolidinediones and insulin-promoting adipogenesis. Pioglitazone increased the fat mass in the upper limbs and trunk, while inducing less increase in the lower limbs, where fat atrophy exists in this patient. Pioglitazone may thus have improved the glycemic control in this case through adipocyte differentiation from progenitor cells mainly in the upper limbs and trunk.

Inherited lipodystrophies and hypertriglyceridemia

PURPOSE OF REVIEW

Inherited lipodystrophies are rare autosomal recessive and dominant disorders characterized by selective, but variable, loss of adipose tissue. Marked hypertriglyceridemia is a common feature of these disorders and highlights the role of adipose tissue in lipid homeostasis. In the last decade, advances have been made in elucidating the molecular basis of many inherited lipodystrophies. We review the new insights in the pathophysiology and treatment of these disorders based on the current understanding of the biologic role of these lipodystrophy genes.

RECENT FINDINGS

Eight different genetic loci, including 1-acylglycerol-3-phosphate-O-acyltransferase 2, Berardinelli-Seip congenital lipodystrophy 2, caveolin 1, lamin A/C, peroxisome proliferator-activated receptor gamma, v-AKT murine thymoma oncogene homolog 2, zinc metalloprotease and lipase maturation factor 1 have been described linked to different lipodystrophy syndromes. Mutations in these genes may cause fat loss and dyslipidemia through multiple mechanisms, which remain fully elucidated; however, they may involve defects in development and differentiation of adipocytes, and premature death and apoptosis of adipocytes. Hypertriglyceridemia is a consequence of increased VLDL synthesis from the liver, which is also loaded by ectopic triglyceride deposition, reduced clearance of triglyceride-rich lipoproteins or both. A recent study in mice with Agpat2 deficiency reports marked reduction in serum triglyceride upon feeding a fat-free diet, which suggests that low-fat diets are likely to be beneficial in lipodystrophic patients. Leptin replacement therapy is also a promising therapeutic option for lipodystrophic patients with hypoleptinemia.

SUMMARY

Inherited lipodystrophies are an important cause for monogenic hypertriglyceridemia and serve to highlight the role of adipocytes in maintaining normolipidemia.