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

Is the endotoxin-complement cascade the major driver in lipedema?

Lipedema is a poorly understood disorder of adipose tissue characterized by abnormal but symmetrical deposition of subcutaneous white adipose tissue (WAT) in proximal extremities. Here, we propose that the underlying cause for lipedema could be triggered by a selective accumulation of bacterial lipopolysaccharides (LPS; also known as endotoxin) in gluteofemoral WAT. Together with a malfunctioning complement system, this induces low-grade inflammation in the depot and raises its uncontrollable expansion. Correspondingly, more attention should be paid in future research to the endotoxemia prevalent in patients with lipedema. We would like to propose that proper management of endotoxemia can reduce the progression and even improve the state of disease in patients with lipedema.

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

BACKGROUND

Barraquer-Simons syndrome (BSS) is a rare, acquired form of lipodystrophy characterized by progressive loss of upper body subcutaneous fat, which affects face, upper limbs, and trunk. The pathogenesis of the disease is not entirely known and may involve autoimmune mechanisms.

AIM

This study aimed to provide a comprehensive picture of the clinical, immunological, and metabolic features of a large cohort of patients with BSS. Our primary objectives included the validation of existing diagnostic tools, the evaluation of novel diagnostic approaches, and the exploration of potential disease triggers or genetic predispositions.

SUBJECTS AND METHODS

Twenty-six patients were diagnosed with BSS based on accepted criteria defined by international guidelines. Anthropometric parameters, biochemical tests, organ- and non-organ-specific autoantibodies, HLA status, and screening of the LMNB2 gene were performed.

RESULTS

Patients were predominantly females (73%); fat loss occurred mostly during childhood (77%) at a median age of 8 years. Among various anthropometric measures, the ratio between the proportion of fat mass in upper limbs and lower limbs showed the best predictive value for diagnosis. A total of 11.5% of patients had diabetes, 34.6% dyslipidemia, and 26.9% hepatic steatosis. Seventy-five percent of children and 50% of adults had C3 hypocomplementemia; 76% of patients were positive for 1 or more autoantibodies. HLA-DRB1 11:03 had higher allelic frequencies compared with the general population. A single variant in the LMNB2 gene was found in 1 patient.

CONCLUSION

BSS has a childhood onset and is often associated with autoimmune diseases. Skinfold thickness measurements and fat assessment by dual energy X-ray absorptiometry are useful tools to identify the disease. C3 hypocomplementemia and the presence of autoantibodies may be used as additional diagnostic supportive criteria but the prevalence of C3 hypocomplementemia may be lower than previously reported.

Concentration of Selected Adipokines and Factors Regulating Carbohydrate Metabolism in Patients with Head and Neck Cancer in Respect to Their Body Mass Index

Head and neck cancers (HNCs) are a group of tumors not common in European populations. So far, not much is known about the role of obesity, adipokines, glucose metabolism, and inflammation in the pathogenesis of HNC. The aim of the study was to determine the concentrations of ghrelin, omentin-1, adipsin, adiponectin, leptin, resistin, visfatin, glucagon, insulin, C-peptide, glucagon-like peptide-1 (GLP-1), plasminogen activator inhibitor-1 (PAI-1), and gastric inhibitory peptide (GIP) in the blood serum of HNC patients depending on their body mass index (BMI). The study included 46 patients divided into two groups according to their BMI values: the normal BMI group (nBMI) included 23 patients with BMI < 25 kg/m² and the increased BMI group (iBMI) included patients with BMI ≥ 25 kg/m². A control group (CG) included 23 healthy people (BMI < 25 kg/m²). Statistically significant differences in the levels of adipsin, ghrelin, glucagon, PAI-1, and visfatin were shown between nBMI and CG. In the case of nBMI and iBMI, statistically significant differences were observed in the concentrations of adiponectin, C-peptide, ghrelin, GLP-1, insulin, leptin, omentin-1, PAI-1, resistin, and visfatin. The obtained results indicate a disruption of endocrine function of adipose tissue and impaired glucose metabolism in HNC. Obesity, which is not a typical risk factor for HNC, may aggravate the negative metabolic changes associated with this type of neoplasm. Ghrelin, visfatin, PAI-1, adipsin, and glucagon might be related to head and neck carcinogenesis. They seem to be promising directions for further research.

Adipsin Serum Concentrations and Adipose Tissue Expression in People with Obesity and Type 2 Diabetes

(1) Adipsin is an adipokine that may link increased fat mass and adipose tissue dysfunction to obesity-related cardiometabolic diseases. Here, we investigated whether adipsin serum concentrations and adipose tissue (AT) adipsin mRNA expression are related to parameters of AT function, obesity and type 2 diabetes (T2D). (2) Methods: A cohort of 637 individuals with a wide range of age and body weight (Age: 18–85 years; BMI: 19–70 kg/m2) with (n = 237) or without (n = 400) T2D was analyzed for serum adipsin concentrations by ELISA and visceral (VAT) and subcutaneous (SAT) adipsin mRNA expression by RT-PCR. (3) Results: Adipsin serum concentrations were significantly higher in patients with T2D compared to normoglycemic individuals. We found significant positive univariate relationships of adipsin serum concentrations with age (r = 0.282, p < 0.001), body weight (r = 0.264, p < 0.001), fasting plasma glucose (r = 0.136, p = 0.006) and leptin serum concentrations (r = 0.362, p < 0.001). Neither VAT nor SAT adipsin mRNA expression correlated with adipsin serum concentrations after adjusting for age, sex and BMI. Independent of T2D status, we found significantly higher adipsin expression in SAT compared to VAT (4) Conclusions: Our data suggest that adipsin serum concentrations are strongly related to obesity and age. However, neither circulating adipsin nor adipsin AT expression reflects parameters of impaired glucose or lipid metabolism in patients with obesity with or without T2D.

Functional Identification of Complement Factor D and Analysis of Its Expression during GCRV Infection in Grass Carp (Ctenopharyngodon idella)

Complement factor D (Df) is a serine protease well known for activating the alternative pathway (AP) in mammals by promoting the cleavage of complement component 3 (C3), thus becoming involved in innate defense. In teleost fish, however, the functional mechanisms of Df in the AP and against pathogen infection are far from clear. In the present study, we cloned and characterized the Df gene, CiDf, from grass carp (Ctenopharyngodon idella) and analyzed its function in promoting C3 cleavage and expression changes after grass carp reovirus (GCRV) infection. The open reading frame of CiDf was found to be 753 bp, encoding 250 amino acids with a molecular mass of 27.06 kDa. CiDf harbors a conserved Tryp_SPc domain, with three conserved residues representing the catalytic triad and three conserved binding sites in the substrate specificity pocket. Pairwise alignment showed that CiDf shares the highest identity (96%) and similarity (98%) with Df from Anabarilius grahami. Phylogenetic analysis indicated that CiDf and other fish Dfs formed a distinct evolutionary branch. Similar to most Dfs from other vertebrates, the CiDf gene structure is characterized by four introns and five exons. The incubation of recombinant CiDf protein with grass carp serum significantly increased the C3b content, demonstrating the conserved function of CiDf in the AP in promoting C3 cleavage, similar to Dfs in mammals. CiDf mRNA expression was widely detected in various tissues and levels were relatively higher in the liver, spleen, and intestine of grass carp. During GCRV infection over a 168-hour period, a high level of CiDf mRNA expression in the liver, spleen, and intestine was maintained at 144 and 168 h, suggesting AP activity at the late stage of GCRV infection. Collectively, the above results reveal the conserved structure and function of CiDf and its distinct expression patterns after GCRV infection, which provide a key basis for studying the roles of Df and AP during GCRV infection in the grass carp C. idella.

Autoimmunity in lipodystrophy syndromes

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