Werner syndrome: a model for sarcopenia due to accelerated aging

Body Fat Distribution Contributes to Defining the Relationship between Insulin Resistance and Obesity in Human Diseases

The risk for metabolic and cardiovascular complications of obesity is defined by body fat distribution rather than global adiposity. Unlike subcutaneous fat, visceral fat (including hepatic steatosis) reflects insulin resistance and predicts type 2 diabetes and cardiovascular disease. In humans, available evidence indicates that the ability to store triglycerides in the subcutaneous adipose tissue reflects enhanced insulin sensitivity. Prospective studies document an association between larger subcutaneous fat mass at baseline and reduced incidence of impaired glucose tolerance. Case-control studies reveal an association between genetic predisposition to insulin resistance and a lower amount of subcutaneous adipose tissue. Human peroxisome proliferator-activated receptorgamma (PPAR-γ) promotes subcutaneous adipocyte differentiation and subcutaneous fat deposition, improving insulin resistance and reducing visceral fat. Thiazolidinediones reproduce the effects of PPAR-γ activation and therefore increase the amount of subcutaneous fat while enhancing insulin sensitivity and reducing visceral fat. Partial or virtually complete lack of adipose tissue (lipodystrophy) is associated with insulin resistance and its clinical manifestations, including essential hypertension, hypertriglyceridemia, reduced HDL-c, type 2 diabetes, cardiovascular disease, and kidney disease. Patients with Prader Willi syndrome manifest severe subcutaneous obesity without insulin resistance. The impaired ability to accumulate fat in the subcutaneous adipose tissue may be due to deficient triglyceride synthesis, inadequate formation of lipid droplets, or defective adipocyte differentiation. Lean and obese humans develop insulin resistance when the capacity to store fat in the subcutaneous adipose tissue is exhausted and deposition of triglycerides is no longer attainable at that location. Existing adipocytes become large and reflect the presence of insulin resistance.

Senescence-associated inflammation and inhibition of adipogenesis in subcutaneous fat in Werner syndrome

Werner syndrome (WS) is a hereditary premature aging disorder characterized by visceral fat accumulation and subcutaneous lipoatrophy, resulting in severe insulin resistance. However, its underlying mechanism remains unclear. In this study, we show that senescence-associated inflammation and suppressed adipogenesis play a role in subcutaneous adipose tissue reduction and dysfunction in WS. Clinical data from four Japanese patients with WS revealed significant associations between the decrease of areas of subcutaneous fat and increased insulin resistance measured by the glucose clamp. Adipose-derived stem cells from the stromal vascular fraction derived from WS subcutaneous adipose tissues (WSVF) showed early replicative senescence and a significant increase in the expression of senescence-associated secretory phenotype (SASP) markers. Additionally, adipogenesis and insulin signaling were suppressed in WSVF, and the expression of adipogenesis suppressor genes and SASP-related genes was increased. Rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR), alleviated premature cellular senescence, rescued the decrease in insulin signaling, and extended the lifespan of WS model of C. elegans. To the best of our knowledge, this study is the first to reveal the critical role of cellular senescence in subcutaneous lipoatrophy and severe insulin resistance in WS, highlighting the therapeutic potential of rapamycin for this disease.

Renal dysfunction, malignant neoplasms, atherosclerotic cardiovascular diseases, and sarcopenia as key outcomes observed in a three-year follow-up study using the Werner Syndrome Registry

Werner syndrome is an adult-onset progeria syndrome that results in various complications. This study aimed to clarify the profile and secular variation of the disease. Fifty-one patients were enrolled and registered in the Werner Syndrome Registry. Their data were collected annually following registration. A cross-sectional analysis at registration and a longitudinal analysis between the baseline and each subsequent year was performed. Pearson's chi-squared and Wilcoxon signed-rank tests were used. Malignant neoplasms were observed from the fifth decade of life (mean onset: 49.7 years) and were observed in approximately 30% of patients during the 3-year survey period. Regarding renal function, the mean estimated glomerular filtration rate calculated from serum creatinine (eGFRcre) and eGFRcys, which were calculated from cystatin C in the first year, were 98.3 and 83.2 mL/min/1.73 m2, respectively, and differed depending on the index used. In longitudinal analysis, the average eGFRcre for the first and fourth years was 74.8 and 63.4 mL/min/1.73 m2, showing a rapid decline. Secular changes in Werner syndrome in multiple patients were identified. The prevalence of malignant neoplasms is high, and renal function may decline rapidly. It is, therefore, necessary to carry out active and detailed examinations and pay attention to the type and dose of the drugs used.

Examination of the body composition of patients with Werner syndrome using bioelectrical impedance analysis

AIM

This study performed anthropometric measurements for Werner syndrome (WS) using bioelectrical impedance analysis and compared them with the Japanese reference data.

METHODS

The analytical sample included nine participants with WS (four men, five women, 49.6 ± 9.3 years, SD). The height-corrected appendicular skeletal muscle mass index (SMI), upper- and lower-limb muscle mass index (USMI/LSMI) of the patients with WS were compared with the Japanese reference data (40-79 years). The body mass index, SMI, height-corrected fat mass index (FMI) and fat-free mass index (FFMI) were compared with the reference data of Japanese older adults (65-94 years). The SMIs of WS were also compared with the diagnostic criteria for sarcopenia.

RESULTS

The SMI and USMI/LSMI of all participants with WS were lower than the Japanese reference data corresponding to gender and age, and the rate of decrease was more pronounced for USMI than for LSMI. The body mass index, SMI and FFMI for all the WS cases were lower than those for the older Japanese, while the FMI was higher in men with WS but lower in women than the reference data of the older Japanese. The SMI was below the cut-off value for the diagnosis of sarcopenia in all patients with WS.

CONCLUSION

The SMI for WS is comparable with that for sarcopenia and significantly lower than that for healthy individuals of the same age and older adults. The USMI was significantly lower than LSMI in patients with WS, and FMI was higher in male patients with WS and lower in women than in healthy older people. Geriatr Gerontol Int ••; ••: ••-•• Geriatr Gerontol Int 2021; ••: ••-••.

Atherosclerosis and Cardiovascular Diseases in Progeroid Syndromes

Hutchinson–Gilford progeria syndrome (HGPS) and Werner syndrome (WS) are two of the representative genetic progeroid syndromes and have been widely studied in the field of aging research. HGPS is a pediatric disease in which premature aging symptoms appear in early childhood, and death occurs at an average age of 14.5 years, mainly due to cardiovascular disease (CVD). Conversely, WS patients exhibit accelerated aging phenotypes after puberty and die in their 50s due to CVD and malignant tumors. Both diseases are models of human aging, leading to a better understanding of the aging-associated development of CVD. In this review, we discuss the pathogenesis and treatment of atherosclerotic diseases presented by both progeroid syndromes with the latest findings.

Fibroblasts from different body parts exhibit distinct phenotypes in adult progeria Werner syndrome

Werner syndrome (WS), also known as adult progeria, is characterized by accelerated aging symptoms from a young age. Patients with WS experience painful intractable skin ulcers with calcifications in their extremities, subcutaneous lipoatrophy, and sarcopenia. However, there is no significant abnormality in the trunk skin, where the subcutaneous fat relatively accumulates. The cause of such differences between the limbs and trunk is unknown. To investigate the underlying mechanism behind these phenomena, we established and analyzed dermal fibroblasts from the foot and trunk of two WS patients. As a result, WS foot-derived fibroblasts showed decreased proliferative potential compared to that from the trunk, which correlated with the telomere shortening. Transcriptome analysis showed increased expression of genes involved in osteogenesis in the foot fibroblasts, while adipogenic and chondrogenic genes were downregulated in comparison with the trunk. Consistent with these findings, the adipogenic and chondrogenic differentiation capacity was significantly decreased in the foot fibroblasts in vitro. On the other hand, the osteogenic potential was mutually maintained and comparable in the foot and trunk fibroblasts. These distinct phenotypes in the foot and trunk fibroblasts are consistent with the clinical symptoms of WS and may partially explain the underlying mechanism of this disease phenotype.

Evaluation of glucose tolerance and effect of dietary management on increased visceral fat in a patient with Werner syndrome

Werner syndrome (WS), a type of progeria, is a hereditary condition caused by a mutation in the WRN gene. A 62-year-old Japanese woman was diagnosed with WS at the age of 32 and has been visiting the hospital for follow-up since the last 30 years. The patient developed diabetes at the age of 46, and at the age of 60, her body mass index increased from 20.1 to 22.7 kg/m² owing to her unhealthy eating habits; her visceral fat area at the age of 61 was 233 cm². With dietary control, her body weight, including the visceral fat and subcutaneous fat, decreased at the age of 62, and her insulin secretion, obesity, and fatty liver improved. We conducted the oral glucose challenge test four times, including at the prediabetic stage, to evaluate the insulin-secretion ability. The patient's insulin resistance gradually increased for more than 14 years, and her insulin secretion ability began to decrease 14 years after her diabetes diagnosis. Despite a remarkable decrease in body weight and fat mass with dietary management, the psoas muscle index did not decrease significantly in proportion to the body weight or fat mass. However, muscle mass monitoring is important for preventing the progression of sarcopenia. Hence, gradual reduction of visceral fat and weight by dietary management may be useful in treating diabetes in patients with WS, particularly in those whose visceral fat is significantly increased.

Management guideline for Werner syndrome 2020. 3. Diabetes associated with Werner syndrome

AIMS

To evaluate the characteristics of diabetes associated with Werner syndrome.

METHODS

A literature search was done with search term "Werner syndrome" and "Diabetes".

RESULTS AND CONCLUSIONS

Prevalence of diabetes is extremely high in Werner syndrome. Diabetes associated with Werner syndrome is classified as "accompanied with other diseases and conditions and the one occurring mainly in association with other genetic syndromes." This type of diabetes is marked by accumulated visceral fat and high insulin resistance, despite low body mass index. Thiazolidine derivatives and metformin are effective for glycemic control. New antidiabetic drugs, such as dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists, could be potentially beneficial for patients with Werner syndrome. Furthermore, the establishment of diet therapy as well as exercise therapy is warranted. Geriatr Gerontol Int 2021; 21: 142-145.

Management guideline for Werner syndrome 2020. 2. Sarcopenia associated with Werner syndrome

AIM

Sarcopenia is defined as a condition that combines decreased skeletal muscle mass with weakness or decreased physical function. It is well known that in older adults, the presence of sarcopenia is a risk of frailty, falls and physical dysfunction. Patients with Werner syndrome are characterized by visceral fat accumulation and thin limbs, but the prevalence of sarcopenia in patients with Werner syndrome has not been investigated.

METHODS

A literature search was conducted using Werner syndrome and skeletal muscle as keywords. We also analyzed data from our 7 Werner syndrome patients.

RESULTS

A literature search on the relationship between Werner syndrome and skeletal muscle yielded only one article reported from Japan. According to this paper, a decrease in skeletal muscle mass (appendicular skeletal muscle index) was observed in all 9 Werner syndromes investigated. On the other hand, in our 7 Werner syndrome patients, their appendicular skeletal muscle indexes were below the standard value except for one male patient who had continued resistance exercise.

CONCLUSION

The decrease in skeletal muscle mass frequently occurs in patients with Werner syndrome. However, resistance exercise may prevent the appearance of sarcopenia and requires early intervention in patients with Werner syndrome. Geriatr Gerontol Int 2021; 21: 139-141.

Investigator-initiated clinical study of a functional peptide, SR-0379, for limb ulcers of patients with Werner syndrome as a pilot study

AIM

An investigator-initiated clinical study was carried out to evaluate the therapeutic potency of SR-0379 for the treatment of leg ulcers in patients with Werner syndrome.

METHODS

A multicenter, open-label study was carried out from September 2017 to February 2018. The inclusion criteria for leg ulcers were: (i) leg ulcers in patients with Werner syndrome, diabetes or critical limb ischemia/venous stasis; and (ii) a wound size of >1 cm and <6 cm in diameter. Four individuals with Werner syndrome and diabetic ulcers, respectively, were enrolled. SR-0379 (0.1%) was sprayed on skin ulcers once per day for 4 weeks. Efficacy was evaluated by determining the rate of wound size reduction as a primary end-point at 4 weeks after the first treatment compared with the pretreatment wound size. As secondary end-points, the DESIGN-R score index, the 50% wound size reduction ratio, time to wound closure and quantification of wound bacteria were also evaluated. The safety of SR-0379 was evaluated during the study period.

RESULTS

The reduction rate of ulcer size treated with 0.1% SR-0379 was 22.90% (mean) in the Werner syndrome ulcers group (n = 4) and 35.70% (mean) in the diabetic ulcers group (n = 4), respectively. The DESIGN-R score decreased by 4.0 points in the Werner syndrome ulcers group and 4.3 points in the diabetic ulcers group. Two mild adverse events were reported in two patients, and causal relationships were denied in any events.

CONCLUSION

Treatment with SR-0379 was safe, well-tolerated, and effective for leg ulcers of both Werner syndrome and diabetes patients. Geriatr Gerontol Int 2019; 19: 1118-1123.

Diabetes mellitus coexisted with progeria: a case report of atypical Werner syndrome with novel LMNA mutations and literature review

Werner syndrome (WS) is a rare, adult-onset progeroid syndrome. Classic WS is caused by WRN mutation and partial atypical WS (AWS) is caused by LMNA mutation. A 19-year-old female patient with irregular menstruation and hyperglycemia was admitted. Physical examination revealed characteristic faces of progeria, graying and thinning of the hair scalp, thinner and atrophic skin over the hands and feet, as well as lipoatrophy of the extremities, undeveloped breasts at Tanner stage 3, and short stature. The patient also suffered from severe insulin-resistant diabetes mellitus, hyperlipidemia, fatty liver, and polycystic ovarian morphology. Possible WS was considered and both WRN and LMNA genes were analyzed. A novel missense mutation p.L140Q (c.419T>A) in the LMNA gene was identified and confirmed the diagnosis of AWS. Her father was a carrier of the same mutation. We carried out therapy for lowering blood glucose and lipid and improving insulin resistance, et al. The fasting glucose, postprandial glucose and triglyceride level was improved after treatment for 9 days. Literature review of AWS was performed to identify characteristics of the disease. Diabetes mellitus is one of the clinical manifestations of WS and attention must give to the differential diagnosis. Gene analysis is critical in the diagnosis of WS. According to the literature, classic and atypical WS differ in incidence, pathogenic gene, and clinical manifestations. Characteristic dermatological pathology may be significantly more important for the initial identification of AWS. Early detection, appropriate treatments, and regular follow-up may improve prognosis and survival of WS patients.

Evidence for premature aging in a Drosophila model of Werner syndrome

Werner syndrome (WS) is an autosomal recessive progeroid disease characterized by patients' early onset of aging, increased risk of cancer and other age-related pathologies. WS is caused by mutations in WRN, a RecQ helicase that has essential roles responding to DNA damage and preventing genomic instability. While human WRN has both an exonuclease and helicase domain, Drosophila WRNexo has high genetic and functional homology to only the exonuclease domain of WRN. Like WRN-deficient human cells, Drosophila WRNexo null mutants (WRNexoΔ) are sensitive to replication stress, demonstrating mechanistic similarities between these two models. Compared to age-matched wild-type controls, WRNexoΔ flies exhibit increased physiological signs of aging, such as shorter lifespans, higher tumor incidence, muscle degeneration, reduced climbing ability, altered behavior, and reduced locomotor activity. Interestingly, these effects are more pronounced in females suggesting sex-specific differences in the role of WRNexo in aging. This and future mechanistic studies will contribute to our knowledge in linking faulty DNA repair mechanisms with the process of aging.

Endothelial cell senescence in aging-related vascular dysfunction

Increased cardiovascular disease in aging is partly a consequence of the vascular endothelial cell (EC) senescence and associated vascular dysfunction. In this contest, EC senescence is a pathophysiological process of structural and functional changes including dysregulation of vascular tone, increased endothelium permeability, arterial stiffness, impairment of angiogenesis and vascular repair, and a reduction of EC mitochondrial biogenesis. Dysregulation of cell cycle, oxidative stress, altered calcium signaling, hyperuricemia, and vascular inflammation have been implicated in the development and progression of EC senescence and vascular disease in aging. A number of abnormal molecular pathways are associated with these underlying pathophysiological changes including Sirtuin 1, Klotho, fibroblast growth factor 21, and activation of the renin angiotensin-aldosterone system. However, the molecular mechanisms of EC senescence and associated vascular impairment in aging are not completely understood. This review provides a contemporary update on molecular mechanisms, pathophysiological events, as well functional changes in EC senescence and age-associated cardiovascular disease. This article is part of a Special Issue entitled: Genetic and epigenetic regulation of aging and longevity edited by Jun Ren & Megan Yingmei Zhang.

Recent Advances in Understanding Werner Syndrome

Aging, the universal phenomenon, affects human health and is the primary risk factor for major disease pathologies. Progeroid diseases, which mimic aging at an accelerated rate, have provided cues in understanding the hallmarks of aging. Mutations in DNA repair genes as well as in telomerase subunits are known to cause progeroid syndromes. Werner syndrome (WS), which is characterized by accelerated aging, is an autosomal-recessive genetic disorder. Hallmarks that define the aging process include genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulation of nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication. WS recapitulates these hallmarks of aging and shows increased incidence and early onset of specific cancers. Genome integrity and stability ensure the normal functioning of the cell and are mainly guarded by the DNA repair machinery and telomeres. WRN, being a RecQ helicase, protects genome stability by regulating DNA repair pathways and telomeres. Recent advances in WS research have elucidated WRN’s role in DNA repair pathway choice regulation, telomere maintenance, resolution of complex DNA structures, epigenetic regulation, and stem cell maintenance.