Les syndromes lipodystrophiques : des adipopathies congénitales ou acquises

Could metabolic syndrome, lipodystrophy, and aging be mesenchymal stem cell exhaustion syndromes?

One of the most important and complex diseases of modern society is metabolic syndrome. This syndrome has not been completely understood, and therefore an effective treatment is not available yet. We propose a possible stem cell mechanism involved in the development of metabolic syndrome. This way of thinking lets us consider also other significant pathologies that could have similar etiopathogenic pathways, like lipodystrophic syndromes, progeria, and aging. All these clinical situations could be the consequence of a progressive and persistent stem cell exhaustion syndrome (SCES). The main outcome of this SCES would be an irreversible loss of the effective regenerative mesenchymal stem cells (MSCs) pools. In this way, the normal repairing capacities of the organism could become inefficient. Our point of view could open the possibility for a new strategy of treatment in metabolic syndrome, lipodystrophic syndromes, progeria, and even aging: stem cell therapies.

Resistance to leptin-replacement therapy in Berardinelli-Seip congenital lipodystrophy: an immunological origin

CONTEXT

Recently, in a 4-month proof-of-concept trial, beneficial metabolic effects were reported in non-diabetic children with Berardinelli-Seip congenital lipodystrophy (BSCL); this information prompted us to hypothesize that long-term leptin-replacement therapy might improve or reverse the early complications of the disease in these patients.

PATIENTS AND METHODS

A 28-month trial was implemented in eight patients. Efficacy assessment was based on a decrease in serum triglyceride concentrations, and/or a decrease in liver volume and/or an increase in insulin sensitivity of at least 30% respectively. The response was defined as follows: total (3/3 positive criteria), partial (1 or 2/3), or negative (0/3). Anti-leptin antibodies were measured with a radiobinding assay, and a neutralizing effect was assessed in primary cultures of embryonic neurons incubated with an apoptotic agent (N-methyl-D-aspartate) and the patient serum, with or without leptin.

RESULTS

A negative or partial response to treatment was observed in five of eight patients even when leptin dosages were increased. A displaceable leptin binding was detectable in all patients after 2 months of treatment. At 28 months, binding was higher in the patients with a negative response than in the total responders, and it paralleled both the increase in leptin dosage and serum leptin concentrations. Co-incubation of embryonic neurons with serum from two patients with a negative response inhibited the neuroprotective effect of leptin.

CONCLUSION

Under leptin therapy, patients with BSCL may develop a resistance to leptin, which could be partly of immunological origin, blunting the previously reported beneficial effects.

Acquired acral lipodystrophy in a 6-year-old girl

We report a case of partial lipodystrophy in a 6-year-old girl with normal lipid and glucose metabolism and no family history for similar disorders. The clinical presentation, the laboratory investigations and the natural history in our patient do not match the diagnostic criteria for any of the established lipodystrophy subsets.

Unusual distribution of the lower body fatty tissue: classification, treatment, and differential diagnosis

Unusual fat distribution of the lower part of the body is clinically characterized by massive symmetric and diffuse fat deposition in the trochanters, groins, buttocks, hips, and lower extremities, which contrasts sharply with the normal upper part of the body. The massive lipomatoses of the lower part of the body can be classified into 3 types: type 1, the familial symmetrical lipomatosis that affects the groins, trochanters, hips, buttocks, and thighs; type 2, the bilateral peritrochanteric familial lipomatoses; and type 3, the unilateral peritrochanteric lipomatosis. This unusual adiposity runs in families and predominantly exists in the Mediterranean region, and seems, however, to be common in North Africa. It is rarely reported in the literature. In this regard, a differential diagnosis is presented regarding the lipomatosis and lipodystrophies-described syndromes to familiarize plastic surgeons with these unique deformities. Between 2000 and 2006, 50 women with abnormal diffuse fat deposits in the lower part of the body were investigated and treated with conventional liposuction; patients' ages ranged between 20 to 46 years. Laboratory examination includes the serum concentrations of lipoprotein, cholesterol, triglycerides, uric acid, fasting glucose, and other routine laboratory tests. Endocrinologic tests include serum estradiol and testosterone levels, and thyroid function tests. Histologic examination of the lipoaspirate was performed. All cases were treated with liposuction. For type 1 cases liposuction was performed in stages; the maximum amount of lipoaspirate per setting was 3,000 to 4,000 mL, and for type 2 and type 3 a single stage liposuction was undertaken. Laboratory examination showed normal values and routine parameters were within normal limits. Endocrinologic investigations revealed no abnormalities and histologic examination of lipoaspirate showed normal subcutaneous fatty tissue. The esthetic outcome of all individuals was satisfactory. Abnormal swelling of the lower half of the female body caused by deposition of subcutaneous fat is determined by heredity and seems to be common in North Africa. It is often accompanied by a psychological reaction due to the disturbed body image. A clinical classification is reported in the current study. The traditional liposuction is the treatment of choice for these esthetic deformities.

IRM du tissu adipeux abdominal et lipodystrophie VIH, étude cas-témoin

PURPOSE

To characterize intra-abdominal adipose tissue changes in HIV patients with clinical lipodystrophy using a reproducible imaging technique. Materials and methods. 89 HIV patients with clinical lipodystrophy were included. A single axial T1W image was acquired at the mid L4 vertebral level. Two radiologists measured subcutaneous (SAT) and visceral (VAT) adipose tissues using a semi-automated method. Measurements were compared to a matched population (race, sex, age and BMI).

RESULTS

Measurements of abdominal adipose tissue on MRI are reproducible. Three clinical types of lipodystrophy are described in males with increased visceral (VAT) and reduced subcutaneous (SAT) adipose tissues compared to control subjects. Two clinical types of lipodystrophy are described in females with increased visceral (VAT) and unchanged subcutaneous (SAT) adipose tissues.

CONCLUSION

MRI with comparison between HIV patients and normal control subjects is a reproducible method to characterize adipose tissue changes of lipodystrophy and evaluate its severity. Evaluation of a adipose tissue distribution in a large control population would be helpful to the study of metabolic disorders.

[Primary lipodystrophies]

Primary lipodystrophies represent a heterogeneous group of very rare diseases with a prevalence of less than 1 case for 100.000, inherited or acquired, caracterized by a loss of body fat either generalized or localized (lipoatrophy). In some forms, lipoatrophy is associated with a selective hypertrophy of other fat depots. Clinical signs of insulin resistance are often present: acanthosis nigricans, signs of hyperandrogenism. All lipodystrophies are associated with dysmetabolic alterations with insulin resistance, altered glucose tolerance or diabetes and hypertriglyceridemia leading to a risk of acute pancreatitis. Chronic complications are those resulting from diabetes involving the retina, kidney and nerves, cardiovascular complications and steatotic liver lesions that could result in cirrhosis. Genetic forms of generalized lipodystrophy (or Berardinelli-Seip syndrome) result, in most cases, from recessive mutations in one of two genes: either BSCL2 coding seipin or BSCL1 coding AGPAT2, an acyl-transferase involved in triglyceride synthesis. Acquired generalized lipodystrophy (Lawrence syndrome) is of unknown origin but is sometimes associated with signs of autoimmunity. Partial lipodystrophies can be familial with dominant transmission. Heterozygous mutations have been identified in the LMNA gene encoding nuclear lamin A/C belonging to the nuclear lamina, or in PPARG encoding the adipogenic transcription factor PPARgamma. Some less typical lipodystrophies, associated with signs of premature aging, have been linked to mutations in LMNA or in the ZMPSTE24 gene encoding the protease responsible for the maturation of prelamin A into lamin A. Acquired partial lipodystrophy (Barraquer-Simons syndrome) is characterized by cephalothoracic fat loss. Its aetiology is unknown but mutations in LMNB2, encoding the lamina protein lamin B2, could represent susceptibility factors. Highly active antiretroviral treatments for HIV infection are currently the most frequent cause of acquired secondary lipodystrophic syndromes. The genetic diagnosis is performed in specialized laboratories and, in the most severe forms, antenatal diagnosis could be proposed. Treatment of diabetes, dyslipidemia and complications involves the classical intervention strategies. Insulino-sensitizing drugs are useful. Therapeutic trials with recombinant human leptin in patients with very low leptin levels reported good results with respect to the metabolic and liver alterations. The prognosis is linked to the precocity and severity of the diabetic, cardiovascular and liver complications.