Adipose Atrophy Research Articles

Pathological Investigation of Double–Stranded DNA Breaks and DNA Oxidation in Natural Infection with Mycobacterium avium subspecies paratuberculosis in Goats

Paratuberculosis, created by Mycobacterium avium subspecies paratuberculosis (MAP), manifests as a chronic affliction marked by persistent diarrhoea and granulomatous enteritis, pervasive in both domestic and global wild ruminants. In this investigation, DNA disruption in lesioned tissues of goat as natural infecte with MAP was pathologically assessed. Accordingly, goats manifesting symptoms suggestive to paratuberculosis, including pronounced emaciation and continual episodic diarrhoea, were subjected to an ELISA diagnostic procedure to ascertain the presence of MAP. This diagnostic approach confirmed the presence of the infectious agent in 20 patients. These patients were subsequently euthanized, and tissue samples from intestinal and regional lenf nods. It were subjected to Hematoxylin and Eosin (HE) staining for histopathological investigatıon, Ziehl Neelsen (ZN) staining to identify acid–fast mycobacteria, γ–H2AX to discern disruptions in double stranded DNA, and 8–Ohdg to detect DNA oxidation by immunohistochemical (IHC) method. Gross anatomical observation serous adipose atrophy, augmented dimensions of mesenterial lymphatic nodes, mucosal hypertrophy and non–retractable mucosal undulations. Histological assessment highlighted epithelial cellular degeneration, an abundance of epithelioid macrophages, lymphocytes, plasmocytes, infiltrating in mucosa. Acid–fast entities, discernible through ZN staining, appeared as luminescent red conglomerates in intestinal and mesenterial tissue. The immunohistochemical analyses evinced positive results for both γ–H2AX and 8–Ohdg across all sampled tissues. Intriguingly, this investigation presented the inaugural global evidence of γ–H2AX and 8–Ohdg expression in a natural MAP infection, demonstrating that this pathological agent precipitates DNA degradation and oxidation, thereby augmenting comprehension of the disease’s pathogenesis.

Exosomal miRNA 16-5p/29a-3p from pancreatic cancer induce adipose atrophy by inhibiting adipogenesis and promoting lipolysis

Over 80% of the patients with pancreatic ductal adenocarcinoma (PDAC) have cachexia/wasting syndrome. Cachexia is associated with reduced survival, decreased quality of life, and higher metastasis rates. Here, we demonstrate that fat loss is the earliest feature of PDAC-exosome-induced cachexia. MicroRNA sequencing of exosomal components from normal and cancer-derived exosomes revealed enrichment of miR-16-5p, miR-21-5p, miR-29a-3p, and miR-125b-5p in serum exosomes of mice harboring PDAC and patients with PDAC. Further, miR-16-5p and miR-29a-3p inhibited adipogenesis through decreasing Erlin2 and Cmpk1 expression which downregulates C/EBPβ and PPARγ. Synergistically, miR-29a-3p promotes lipolysis through increasing ATGL expression by suppressing MCT1 expression. Furthermore, PDAC-exosomes deprived of miR-16-5p and miR-29a-3p fail to induce fat loss. Hence, miR-16-5p and miR-29a-3p exosomal miRs are essential for PDAC-induced fat loss. Thus, we unravel that PDAC induces adipose atrophy via exosomal miRs. This knowledge may provide new diagnostic and therapeutic strategies for PDAC-induced cachexia.

Retrospective review of the pathology of American pikas.

American pikas (Ochotona princeps) are small lagomorphs that live in mountainous talus areas of western North America. Studies on the histopathology of American pikas are limited. We summarize here the clinical histories, and gross and histologic findings of 12 American pikas, including 9 captive (wild-caught) and 3 wild animals. Death was often attributed to stress (transport, handling, anesthesia) with few-to-no premonitory clinical signs. Infection was the cause of death in 2 cases: 1 had bacterial pyogranulomatous dermatitis, cellulitis, and lymphadenitis with sepsis; the other case had oomycete-induced necrotizing colitis. Incidental parasitic infections included sarcocystosis, nematodosis (oxyurids), and ectoparasitism. Most animals with adequate nutritional status had periportal hepatic lipidosis; this finding was absent in all animals with adipose atrophy, and it is possible that periportal hepatic lipidosis is non-pathologic in American pikas. Three cases had myocardial necrosis that was considered the cause of death; the cause of necrosis was not determined, but it may have been caused by stress or vitamin E-selenium deficiency. Esophageal hyperkeratosis was noted in animals with a history of anorexia and negative energy balance; accumulation of esophageal keratin can result from lack of mucosal abrasion by ingesta. Several histologic findings that are likely normal in American pikas include splenic extramedullary hematopoiesis, thymic tissue in adults, and Clostridium sp. in the enteric lumen.

Adipose transplantation improves metabolism and atherosclerosis but not perivascular adipose tissueabnormality or vascular dysfunction in lipodystrophic Seipin/Apoe null mice.

Adipose dysfunction in lipodystrophic SEIPIN deficiency is associated with multiple metabolic disorders and increased risks of developing cardiovascular diseases, such as atherosclerosis, cardiac hypertrophy, and heart failure. Recently, adipose transplantation has been found to correct adipose dysfunction and metabolic disorders in lipodystrophic Seipin knockout mice; however, whether adipose transplantation could improve lipodystrophy-associated cardiovascular consequences is still unclear. Here, we aimed to explore the effects of adipose transplantation on lipodystrophy-associated metabolic cardiovascular diseases in Seipin knockout mice crossed into atherosclerosis-prone apolipoprotein E (Apoe) knockout background. At 2 months of age, lipodystrophic Seipin/Apoe double knockout mice and nonlipodystrophic Apoe knockout controls were subjected to adipose transplantation or sham operation. Seven months later, mice were euthanized. Our data showed that although adipose transplantation had no significant impact on endogenous adipose atrophy or gene expression, it remarkably increased plasma leptin but not adiponectin concentration in Seipin/Apoe double knockout mice. This led to significantly reduced hyperlipidemia, hepatic steatosis, and insulin resistance in Seipin/Apoe double knockout mice. Consequently, atherosclerosis burden, intraplaque macrophage infiltration, and aortic inflammatory gene expression were all attenuated in Seipin/Apoe double knockout mice with adipose transplantation. However, adipocyte morphology, macrophage infiltration, or fibrosis of the perivascular adipose tissue was not altered in Seipin/Apoe double knockout mice with adipose transplantation, followed by no significant improvement of vasoconstriction or relaxation. In conclusion, we demonstrate that adipose transplantation could alleviate lipodystrophy-associated metabolic disorders and atherosclerosis but has an almost null impact on perivascular adipose abnormality or vascular dysfunction in lipodystrophic Seipin/Apoe double knockout mice.NEW & NOTEWORTHY Adipose transplantation (AT) reverses multiply metabolic derangements in lipodystrophy, but whether it could improve lipodystrophy-related cardiovascular consequences is unknown. Here, using Seipin/Apoe double knockout mice as a lipodystrophy disease model, we showed that AT partially restored adipose functionality, which translated into significantly reduced atherosclerosis. However, AT was incapable of reversing perivascular adipose abnormality or vascular dysfunction. The current study provides preliminary experimental evidence on the therapeutic potential of AT on lipodystrophy-related metabolic cardiovascular diseases.

Abstract 459: Exosomal miRNA 16-5p/29a-3p secreted from pancreatic cancer induce adipose atrophy by inhibiting adipogenesis and promoting lipolysisExosomal miRNA 16-5p/29a-3p secreted from pancreatic cancer induce adipose atrophy by inhibiting adipogenesis and promoting lipolysis

Abstract Over 80% of the patients with pancreatic ductal adenocarcinoma (PDAC) have cachexia, which is associated with reduced survival, decreased quality of life, and higher rates of metastatic disease. To date, the diagnostic and therapeutic options of PDAC-associated cachexia remain limited due to the lack of a complete understanding of the underlying pathological mechanism. Here, we demonstrate that fat loss is the earliest feature of cachexia induced by PDAC through its secreted exosomes. By analyzing exosomal components of normal and cancer-derived exosomes through small RNA-seq, we identify miR-16-5p, miR-21-5p, miR-29a-3p and miR-125b-5p enriched in pancreatic cancer-derived exosomes and in the exosomes from sera of mice or patients with pancreatic tumor. Among these, miR-16-5p and miR-29a-3p play a key role in fat loss by inhibiting adipogenesis through decreasing Erlin2 and CMPK1 expression leading to C/EBPβ and PPARγ downregulation. Synergistically, miR-29a-3p increases ATGL expression to facilitate lipolysis by suppressing MCT1 expression. Furthermore, PDAC-derived exosomes deprived of miR-16-5p and miR-29a-3p fail to induce fat loss, suggesting that these two exosomal miRs are required for PDAC-induced fat loss. These findings unravel a precise mechanism of how PDAC causes adipose atrophy via exosomal miRs and may provide new diagnostic and therapeutic strategies for PDAC-induced cachexia. Citation Format: Sui-Chih Tien, Chin-Chun Chang, I-Chih Chen, Ching-Hsuan Huang, Hsuan-Yu Peng, Yu-Ting Chang, Ming-Chu Chang, Chun-Mei Hu, Wen-Hwa Lee. Exosomal miRNA 16-5p/29a-3p secreted from pancreatic cancer induce adipose atrophy by inhibiting adipogenesis and promoting lipolysisExosomal miRNA 16-5p/29a-3p secreted from pancreatic cancer induce adipose atrophy by inhibiting adipogenesis and promoting lipolysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 459.

Curcuma xanthorrhiza extract and xanthorrhizol ameliorate cancer-induced adipose wasting in CT26-bearing mice by regulating lipid metabolism and adipose tissue browning

BackgroundCancer cachexia—characterized by anorexia, body weight loss, skeletal muscle atrophy, and fat loss—affects nearly 80% of cancer patients and accounts for 20% of cancer deaths. Curcuma xanthorrhiza, known as Java turmeric, and its active compound xanthorrhizol (XAN) exhibit anticancer, anti-inflammatory, and antioxidant properties. However, the ameliorative effects of C. xanthorrhiza extract (CXE) and XAN on cancer-associated adipose atrophy remain unexplored. This study aimed to evaluate the therapeutic effects of CXE and XAN on cancer cachexia-induced adipose tissue wasting in CT26 tumor-bearing mice. MethodsCT26 cells were injected subcutaneously into the right flank of BALB/c mice to establish a cancer cachexia model. To evaluate the inhibitory effects of CXE and XAN on cancer cachexia, 50 and 100 mg/kg CXE and 15 mg/kg XAN were administered orally every day for 1 week. ResultsCXE and XAN administration significantly attenuated the loss of body weight and epidydimal fat mass by cancer cachexia. In epididymal adipose tissues, administration of CXE or XAN inhibited white adipose tissue browning by repressing expression of the thermogenic genes. Simultaneously, CXE or XAN attenuated fat catabolism through the downregulation of lipolytic genes. The administration of CXE or XAN induced the expression of genes associated with adipogenesis and lipogenesis-related genes. Moreover, CXE or XAN treatment was associated with maintaining metabolic homeostasis; regulating the expression of adipokines and AMP-activated protein kinase (AMPK). ConclusionsCXE and XAN mitigate cancer-induced adipose tissue atrophy, primarily by modulating lipid metabolism and WAT browning, indicating their therapeutic potential for cachectic cancer patients.

Homocysteine-induced endoplasmic reticulum stress activates FGF21 and is associated with browning and atrophy of white adipose tissue in Bhmt knockout mice

Betaine-homocysteine methyltransferase (BHMT) catalyzes the transfer of methyl groups from betaine to homocysteine (Hcy), producing methionine and dimethylglycine. In this work, we characterize Bhmt wild type (Bhmt-WT) and knockout (Bhmt-KO) mice that were fully backcrossed to a C57Bl6/J background. Consistent with our previous findings, Bhmt-KO mice had decreased body weight, fat mass, and adipose tissue weight compared to WT. Histological analyses and gene expression profiling indicate that adipose browning was activated in KO mice and contributed to the adipose atrophy observed. BHMT is not expressed in adipose tissue but is abundant in liver; thus, a signal must originate from the liver that modulates adipose tissue. We found that, in Bhmt-KO mice, homocysteine-induced endoplasmic reticulum (ER) stress is associated with activation of the hepatic transcription factor cyclic AMP response element binding protein (CREBH), and an increase in hepatic and plasma concentrations of fibroblast growth factor 21 (FGF21), which is known to induce adipose browning. Our data indicate that the deletion of a single gene in one-carbon metabolism modifies adipose biology and energy metabolism. Future studies could focus on identifying if functional polymorphisms in BHMT result in a similar adipose atrophy phenotype.

Astragalus polysaccharide prevents heart failure-induced cachexia by alleviating excessive adipose expenditure in white and brown adipose tissue

BackgroundAstragalus polysaccharide (APS) is a key active ingredient isolated from Astragalus membranaceus that has been reported to be a potential treatment for obesity and diabetes by regulating lipid metabolism and adipogenesis, alleviating inflammation, and improving insulin resistance. However, whether APS regulates lipid metabolism in the context of cachexia remains unclear. Therefore, this study analysed the effects of APS on lipid metabolism and adipose expenditure in a heart failure (HF)-induced cardiac cachexia rat model. MethodsA salt-sensitive hypertension-induced cardiac cachexia rat model was used in the present study. Cardiac function was detected by echocardiography. The histological features and fat droplets in fat tissue and liver were observed by H&E staining and Oil O Red staining. Immunohistochemical staining, Western blotting and RT‒qPCR were used to detect markers of lipolysis and adipose browning in white adipose tissue (WAT) and thermogenesis in brown adipose tissue (BAT). Additionally, sympathetic nerve activity and inflammation in adipose tissue were detected.ResultsRats with HF exhibited decreased cardiac function and reduced adipose accumulation as well as adipocyte atrophy. In contrast, administration of APS not only improved cardiac function and increased adipose weight but also prevented adipose atrophy and FFA efflux in HF-induced cachexia. Moreover, APS inhibited HF-induced lipolysis and browning of white adipocytes since the expression levels of lipid droplet enzymes, including HSL and perilipin, and beige adipocyte markers, including UCP-1, Cd137 and Zic-1, were suppressed after administration of APS. In BAT, treatment with APS inhibited PKA-p38 MAPK signalling, and these effects were accompanied by decreased thermogenesis reflected by decreased expression of UCP-1, PPAR-γ and PGC-1α and reduced FFA β-oxidation in mitochondria reflected by decreased Cd36, Fatp-1 and Cpt1. Moreover, sympathetic nerve activity and interleukin-6 levels were abnormally elevated in HF rats, and astragalus polysaccharide could inhibit their activity.ConclusionAPS prevented lipolysis and adipose browning in WAT and decreased BAT thermogenesis. These effects may be related to suppressed sympathetic activity and inflammation. This study provides a potential approach to treat HF-induced cardiac cachexia.

Loss of SQSTM1/p62 Induces Obesity and Exacerbates Alcohol-Induced Liver Injury in Aged Mice

Alcohol-associated liver disease (ALD) is a worldwide health problem, of which the effective treatment is still lacking. Both detrimental and protective roles of adipose tissue have been implicated in ALD. Although alcohol increases adipose tissue lipolysis to promote alcohol-induced liver injury, alcohol also activates brown adipose tissue (BAT) thermogenesis as an adaptive response in protecting against alcohol-induced liver injury. Moreover, aging and obesity are also risk factors for ALD. In the present study, we investigated the effects of autophagy receptor protein SQSTM1/p62 on adipose tissue and obesity in alcohol-induced liver injury in both young and aged mice. Young and aged whole-body SQSTM1/p62 knockout (KO) and their age-matched wild-type (WT) mice were subjected to chronic plus binge (Gao-binge) alcohol feeding. Blood, adipose and liver tissues were collected for biochemical and histologic analysis. Aged but not young SQSTM1/p62 KO mice had significantly increased body weight and fat mass compared with the matched WT mice. Gao-binge alcohol feeding induced white adipose atrophy and decreased levels of SQSTM1/p62 levels in adipose tissue in aged WT mice. SQSTM1/p62 KO aged mice were resistant to Gao-binge alcohol-induced white adipose atrophy. Alcohol feeding increased the expression of thermogenic genes in WT mouse BAT, which was significantly blunted in SQSTM1/p62 KO aged mice. Alcohol-fed aged SQSTM1/p62 KO mice showed significantly higher levels of serum alanine aminotransferase, hepatic triglyceride, and inflammation compared with young and aged WT mice fed with alcohol. Alcohol-fed SQSTM1/p62 KO mice also increased secretion of proinflammatory and angiogenic adipokines that may promote alcohol-induced liver injury. Loss of SQSTM1/p62 in aged mice leads to obesity and impairs alcohol-induced BAT adaptation, resulting in exacerbated alcohol-induced liver injury in mice.

COVID-19 instigates adipose browning and atrophy through VEGF in small mammals

Patients with COVID-19 frequently manifest adipose atrophy, weight loss and cachexia, which significantly contribute to poor quality of life and mortality1,2. Browning of white adipose tissue and activation of brown adipose tissue are effective processes for energy expenditure3–7; however, mechanistic and functional links between SARS-CoV-2 infection and adipose thermogenesis have not been studied. In this study, we provide experimental evidence that SARS-CoV-2 infection augments adipose browning and non-shivering thermogenesis (NST), which contributes to adipose atrophy and body weight loss. In mouse and hamster models, SARS-CoV-2 infection activates brown adipose tissue and instigates a browning or beige phenotype of white adipose tissues, including augmented NST. This browning phenotype was also observed in post-mortem adipose tissue of four patients who died of COVID-19. Mechanistically, high levels of vascular endothelial growth factor (VEGF) in the adipose tissue induces adipose browning through vasculature–adipocyte interaction. Inhibition of VEGF blocks COVID-19-induced adipose tissue browning and NST and partially prevents infection-induced body weight loss. Our data suggest that the browning of adipose tissues induced by COVID-19 can contribute to adipose tissue atrophy and weight loss observed during infection. Inhibition of VEGF signaling may represent an effective approach for preventing and treating COVID-19-associated weight loss.

Nomegestrol acetate ameliorated adipose atrophy in a rat model of cisplatin‑induced cachexia.

Cachexia, a complex disorder that results in depletion of adipose tissue and skeletal muscle, is driven by anorexia, metabolic abnormalities and inflammation. There are limited therapeutic options for this syndrome. Previous evidence has demonstrated that increasing adipose tissue may improve quality of life and survival outcomes in cachexia. Cisplatin, as a chemotherapy drug, also causes cachexia during antitumor therapy due to its adverse effects. To establish a rat model of cachexia, the animals were intraperitoneally treated with cisplatin at doses of 1, 2 and 3 mg/kg, and the rats that responded to cisplatin at the optimal dose were used to test the effect of nomegestrol acetate (NOMAc). Rats that were assessed to be sensitive to cisplatin were randomly grouped and intragastrically administered vehicle, 5 or 10 mg/kg megestrol acetate (MA) or 2.5, 5 or 10 mg/kg NOMAc. The body weights and food consumption of the rats were assessed. Serum IL-6 and TNF-α levels were assessed using ELISA. The protein expression levels of adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), peroxisome proliferator activated receptor γ (PPARγ), fatty acid synthase (FASN) and sterol regulatory element-binding protein-1 (SREBP-1) from inguinal white adipose tissue (iWAT) and epididymal white adipose tissue (eWAT) were evaluated using western blotting. The optimal way to establish a chemotherapy-induced rat model of cachexia demonstrated in the present study was to intraperitoneally administer the rats with 2 mg/kg cisplatin for 3 consecutive days. NOMAc (2.5, 5 mg/kg) and MA (10 mg/kg) were able to significantly ameliorate the loss of body weight in the cisplatin-induced cachectic rats. NOMAc significantly reduced the serum levels of TNF-α at 10 mg/kg. Morphologically, iWAT atrophy, with a remarkable reduction in adipocyte volume, was observed in the cisplatin-induced cachectic rats, but the effects were reversed by administering 5, 10 mg/kg NOMAc or 10 mg/kg MA. Furthermore, 2.5 mg/kg NOMAc markedly reduced the protein expression levels of the lipolysis genes HSL and ATGL, and 5 mg/kg NOMAc markedly enhanced the protein expression levels of adipogenesis genes, including FASN, SREBP-1 and PPARγ in iWAT but not in eWAT. NOMAc was demonstrated to improve cachexia at lower doses compared with MA. Overall, NOMAc is likely to be a promising candidate drug for ameliorating cancer cachexia induced by cisplatin.

Curcumin treatment suppresses cachexia-associated adipose wasting in mice by blocking the cAMP/PKA/CREB signaling pathway

BackgroundCachexia is a multifactorial debilitating syndrome that is responsible for 22% of mortality among cancer patients, and there are no effective therapeutic agents available. Curcumin, a polyphenolic compound derived from the plant turmeric, has been shown to have anti-inflammatory, antioxidant, anti-autophagic, and antitumor activities. However, its function in cancer cachexia remains largely unexplored. PurposeThis study aimed to elucidate the mechanisms by which curcumin improves adipose atrophy in cancer cachexia. MethodsC26 tumor-bearing BALB/c mice and β3-adrenoceptor agonist CL316243 stimulated BALB/c mice were used to observe the therapeutic effects of curcumin on the lipid degradation of cancer cachexia in vivo. The effects of curcumin in vitro were examined using mature 3T3-L1 adipocytes treated with a conditioned medium of C26 tumor cells or CL316243. ResultsMice with C26 tumors and cachexia were protected from weight loss and adipose atrophy by curcumin (50 mg/kg, i.g.). Curcumin significantly reduced serum levels of free fatty acids and increased triglyceride levels. In addition, curcumin significantly inhibited PKA and CREB activation in the adipose tissue of cancer cachectic mice. Curcumin also ameliorated CL316243-induced adipose atrophy and inhibited hormone-mediated PKA and CREB activation in mice. Moreover, the lipid droplet degradation induced by C26 tumor cell conditioned medium in mature 3T3-L1 adipocytes was ameliorated by curcumin (20 µM) treatment. Curcumin also improved the lipid droplet degradation of mature 3T3-L1 adipocytes induced by CL316243. ConclusionCurcumin might be expected to be a therapeutic supplement for cancer cachexia patients, primarily through inhibiting adipose tissue loss via the cAMP/PKA/CREB signaling pathway.

Adipose Tissue Wasting as a Determinant of Pancreatic Cancer-Related Cachexia.

Simple SummaryPancreatic cancer (PC) is one of the deadliest cancers in the US. The poor prognosis of PC is related to diagnostic delay and the presence of unintended weight loss (cachexia) that commonly presents in PC patients even before diagnosis. However, the current understanding of how PC mediates cachexia is limited, and there are few treatments clinically available for cachexia. Based on the current literature, we demonstrate that PC-related cachexia primarily results from the wasting of adipose tissue, once thought to be merely a storage depot but now appreciated as an instrumental metabolic organ in the body. In addition, poor survival in PC patients was found to be associated with adipose tissue loss at diagnosis and during treatment. Therefore, identifying potential mediators and molecular mechanisms underlying adipose tissue loss would promise to pave the way for the development of effective interventions for PC-related cachexiaPancreatic cancer (PC) is the third leading cause of cancer-related death in the US, and its 5-year survival rate is approximately 10%. The low survival rates largely stem from diagnostic delay and the presence of significant adipose tissue and muscle wasting, commonly referred to as cachexia. Cachexia is present in nearly 80% of PC patients and is a key cause of poor response to treatment and about 20% of death in PC patients. However, there are few clinical interventions proven to be effective against PC-related cachexia. Different cancer types feature distinct secretome profiles and functional characteristics which would lead to cachexia development differently. Therefore, here we discuss affected tissues and potential mechanisms leading to cachexia in PC. We postulate that the most affected tissue during the development of PC-related cachexia is adipose tissue, historically and still thought to be just an inert repository for excess energy in relation to cancer-related cachexia. Adipose tissue loss is considerably greater than muscle loss in quantity and shows a correlation with poor survival in PC patients. Moreover, we suggest that PC mediates adipose atrophy by accelerating adipocyte lipid turnover and fibroblast infiltration.

Effects of Cigarette Smoke on Adipose and Skeletal Muscle Tissue: In Vivo and In Vitro Studies.

Chronic obstructive pulmonary disease (COPD), often caused by smoking, is a chronic lung disease with systemic manifestations including metabolic comorbidities. This study investigates adaptive and pathological alterations in adipose and skeletal muscle tissue following cigarette smoke exposure using in vivo and in vitro models. Mice were exposed to cigarette smoke or air for 72 days and the pre-adipose cell line 3T3-L1 was utilized as an in vitro model. Cigarette smoke exposure decreased body weight, and the proportional loss in fat mass was more pronounced than the lean mass loss. Cigarette smoke exposure reduced adipocyte size and increased adipocyte numbers. Adipose macrophage numbers and associated cytokine levels, including interleukin-1β, interleukine-6 and tumor necrosis factor-α were elevated in smoke-exposed mice. Muscle strength and protein synthesis signaling were decreased after smoke exposure; however, muscle mass was not changed. In vitro studies demonstrated that lipolysis and fatty acid oxidation were upregulated in cigarette smoke-exposed pre-adipocytes. In conclusion, cigarette smoke exposure induces a loss of whole-body fat mass and adipose atrophy, which is likely due to enhanced lipolysis.

Alcoholic fatty liver is blunted by rFGF21 administration in mice lacking adipose FGFR1: The role of FGF21 in PPARα-mediated regulation of adipose tissue mass

Fibroblast growth factor 21 (FGF21) is regulated by peroxisome proliferator activated receptor α (PPARα) in the liver. FGF21 regulates lipid metabolism via fibroblast growth factor receptor 1 (FGFR1). FGF21 protect against alcoholic fatty liver (AFL), however, FGF21 does not exert protective effect through liver FGFR1. We have previously shown that PPARα agonist WY-14,643 induces FGF21 and adipose atrophy but fails to protect against chronic ethanol-induced AFL in mice lacking adipose FGFR1. In this study we tested the direct role of the FGF21 in regulation of adipose tissue mass and ethanol induced-hepatic triglyceride (TG) accumulation in normal control (fgfr1fl/fl) mice and in adipose FGFR1 knockout mice (fgfr1adipoQ-cre). First, we tested whether WY-14,643 effects on adipose atrophy and AFL can be recapitulated in binge alcohol model. As in chronic model, adipose tissue mass and serum free fatty acid (FFA) were decreased by WY-14,643 in the fgfr1adipoQ-cre mice but not in the fgfr1fl/fl mice. However, in contrast to the chronic model, binge ethanol-induced AFL was blunted by WY-14,643 to a greater extent in the fgfr1adipoQ-cre mice than in the fgfr1fl/fl mice. Similarly, circulating FGF21 was elevated by binge ethanol to a greater extent in the fgfr1adipoQ-cre mice than in the fgfr1fl/fl mice on top of WY-14,643 treatment. Accordingly, we tested the involvement of the FGF21 in adipose atrophy and AFL. Consistent with FGFR1-dependent effects of WY-14,643 on adipose atrophy and AFL, recombinant mouse FGF21 (rFGF21) injection induced adipose atrophy, blunted AFL and serum TG elevation to a greater extent in the fgfr1adipoQ-cre mice than in the fgfr1fl/fl mice. These results indicated the consistency of adipose FGFR1 dependent effect of WY-14,643 and FGF21 in PPARα-mediated regulation of adipose tissue mass and fat mobilization from adipose tissues to the liver, suggesting that adipose tissues crosstalk with liver through an interaction between liver PPARα-FGF21 and adipose FGFR1 to maintain adipose tissue mass.

Alcoholic fatty liver is blunted by rFGF21 administration in mice lacking adipose FGFR1: the role of FGF21 in PPARα‐mediated regulation of adipose tissue mass

Fibroblast growth factor 21 (FGF21) regulates lipid metabolism via fibroblast growth factor receptor 1 (FGFR1). FGF21 protects against alcoholic fatty liver, which is still observed in mice lacking liver FGFR1, suggesting the involvement of extra‐hepatic FGFR1 in mediating alcoholic fatty liver. We have previously shown that, in a chronic Lieber‐DeCarli model, the peroxisome proliferator‐activated receptor‐α (PPARα) agonist WY‐14,643 induced FGF21 and adipose atrophy but failed to protect against alcoholic fatty liver in mice lacking adipose FGFR1. In this study we tested the role of the FGF21 in regulation of adipose tissue mass and ethanol induced‐hepatic fat (triglyceride, TG) accumulation in mice lacking adipose FGFR1. In binge alcohol model, male adipose FGFR1 knockout mice (fgfr1adipoQ‐cre) and corresponding normal control (fgfr1fl/fl) mice were fed liquid control diet with or without 20 mg/L WY‐14,643 for 2 weeks followed by a binge ethanol gavage at 5 g/kg, adipose tissue mass and serum free fatty acid were decreased by WY‐14,643 in the fgfr1adipoQ‐cremice but not in the fgfr1fl/flmice. However, in contrast to the chronic model, the binge ethanol‐induced liver TG accumulation was blunted by WY‐14,643 to a greater extent in the fgfr1adipoQ‐cremice than in the fgfr1fl/flmice. Consistently, on top of WY‐14,643 feeding, circulating FGF21 was elevated by binge ethanol to a greater extent in the fgfr1adipoQ‐cre mice than in the fgfr1fl/fl mice. To test the involvement of the FGF21 in adipose atrophy and the less extent of hepatic fat accumulation in the fgfr1adipoQ‐cremice, recombinant mouse FGF21 (rFGF21) was injected intraperitoneally at 0.4 mg/kg to the 3‐week ethanol fed fgfr1adipoQ‐cre mice and fgfr1fl/fl mice during the last 10 days of the ethanol feeding. Consistent with FGFR1‐dependent effects of WY‐14,643 on adipose atrophy and liver fat accumulation, on the top of chronic ethanol diet, rFGF21 administration induced adipose atrophy, blunted liver TG accumulation and serum TG elevation to a greater extent in the fgfr1adipoQ‐cre mice than in the fgfr1fl/fl mice. These results indicated the consistency of adipose FGFR1 dependent effect of WY‐14,643 and FGF21 in PPARα‐mediated regulation of adipose tissue mass and fat mobilization from adipose tissues to the liver.

An immune-sympathetic neuron communication axis guides adipose tissue browning in cancer-associated cachexia

Cancer-associated cachexia (CAC) is a hypermetabolic syndrome characterized by unintended weight loss due to the atrophy of adipose tissue and skeletal muscle. A phenotypic switch from white to beige adipocytes, a phenomenon called browning, accelerates CAC by increasing the dissipation of energy as heat. Addressing the mechanisms of white adipose tissue (WAT) browning in CAC, we now show that cachexigenic tumors activate type 2 immunity in cachectic WAT, generating a neuroprotective environment that increases peripheral sympathetic activity. Increased sympathetic activation, in turn, results in increased neuronal catecholamine synthesis and secretion, β-adrenergic activation of adipocytes, and induction of WAT browning. Two genetic mouse models validated this progression of events. 1) Interleukin-4 receptor deficiency impeded the alternative activation of macrophages, reduced sympathetic activity, and restrained WAT browning, and 2) reduced catecholamine synthesis in peripheral dopamine β-hydroxylase (DBH)-deficient mice prevented cancer-induced WAT browning and adipose atrophy. Targeting the intraadipose macrophage-sympathetic neuron cross-talk represents a promising therapeutic approach to ameliorate cachexia in cancer patients.

PPARα agonist WY-14,643 induces adipose atrophy and fails to blunt chronic ethanol-induced hepatic fat accumulation in mice lacking adipose FGFR1

Fibroblast growth factor 21 (FGF21) is mainly regulated by peroxisome proliferator-activated receptor α (PPARα) in liver. The PPARα-FGF21 axis protects against alcohol-related liver disease (ALD). FGF21 exerts its effect via FGF receptor 1 (FGFR1). However, liver specific FGFR1 abrogation had no effect on ALD. Adipose tissues highly express FGFR1. When adipocyte specific FGFR1 knockout (fgfr1adipoQ-cre) mice and corresponding normal control (fgfr1fl/fl) mice were fed with Lieber-DeCarli ethanol liquid diet for 3 weeks, liver triglyceride (TG) accumulation was increased in the fgfr1fl/fl mice to a greater extent than in the fgfr1adipoQ-cre mice. When PPARα agonist WY-14,643 was added in the liquid ethanol diet at 10 mg/L, the ethanol-induced liver TG accumulation was blunted in the fgfr1fl/fl mice but not in the fgfr1adipoQ-cre mice. There was no significant difference in WY-14,643-induced fatty acid oxidation, ethanol metabolism, and oxidative stress between the fgfr1fl/fl and fgfr1adipoQ-cre mice. Interestingly, adipose atrophy was induced by WY-14,643 in the fgfr1adipoQ-cre mice but not in the fgfr1fl/fl mice. Serum free fatty acid was also decreased by WY-14,643 in the fgfr1adipoQ-cre mice but not in the fgfr1fl/fl mice. These results suggest that WY-14,643 inhibits alcoholic fatty liver and regulates adipose tissue mass and fat mobilization from adipose tissues to liver in an adipocyte FGFR1-dependent manner.

Mitochondrial Unfolded Protein Responses in White Adipose Tissue: Lipoatrophy, Whole-Body Metabolism and Lifespan.

The mitochondrial unfolded protein response (UPRmt) is a stress response mediated by the expression of genes such as chaperones, proteases, and mitokines to maintain mitochondrial proteostasis. Certain genetically modified mice, which defect mitochondrial proteins specifically in adipocytes, developed atrophy of the white adipose tissue, resisted diet-induced obesity, and had altered whole-body metabolism. UPRmt, which has beneficial functions for living organisms, is termed “mitohormesis”, but its specific characteristics and detailed regulatory mechanism have not been elucidated to date. In this review, we discuss the function of UPRmt in adipose atrophy (lipoatrophy), whole-body metabolism, and lifespan based on the concept of mitohormesis.

Role of Mechanistic Target of Rapamycin and Autophagy in Alcohol-Induced Adipose Atrophy and Liver Injury

Chronic alcohol consumption induces adipose tissue atrophy. However, the mechanisms for how alcohol induces lipodystrophy and its impact on liver steatosis and injury are not fully elucidated. Autophagy is a highly conserved lysosomal degradation pathway, which regulates cellular homeostasis. Mice with autophagy deficiency in adipose tissue have impaired adipogenesis. However, whether autophagy plays a role in alcohol-induced adipose atrophy and how altered adipocyte autophagy contributes to alcohol-induced liver injury remain unclear. To determine the role of adipose autophagy and mechanistic target of rapamycin (mTOR) in alcohol-induced adipose and liver pathogenesis, we generated adipocyte-specific Atg5 knockout (KO), adipocyte-specific mTOR KO, adipocyte-specific Raptor KO, and adipocyte-specific tuberous sclerosis complex 1 KO mice by crossing floxed mice with Adipoq-Cre. The KO mice and their matched wild-type mice were challenged with chronic-plus-binge alcohol mouse model. Chronic-plus-binge alcohol induced adipose atrophy with increased autophagy and decreased Akt/mTOR signaling in epididymal adipose tissue in wild-type mice. Adipocyte-specific Raptor KO mice experienced exacerbated alcohol-induced steatosis, but neither adipocyte-specific mTOR nor adipocyte-specific tuberous sclerosis complex 1 KO mice exhibited similar detrimental effects. Adipocyte-specific Atg5 KO mice had increased circulating levels of fibroblast growth factor 21 and adiponectin and were resistant to alcohol-induced adipose atrophy and liver injury. In conclusion, autophagy deficiency in adipose tissue leads to reduced sensitivity to alcohol-induced adipose atrophy, which ameliorates alcohol-induced liver injury in mice.