COX-2-mediated inflammation in fat is crucial for obesity-linked insulin resistance and fatty liver

The aim was to examine the role of cyclooxygenase (COX)-2-mediated inflammation in the development of obese linked insulin resistance and fatty liver. The rats were fed separately regular diet (CONT), high-fat diet (HFD) ad libitum, or energy restrictedly for 12 weeks. Rats fed HFD ad libitum were further divided into three subgroups co-treated with vehicle (HFa), or a selective COX-2 inhibitor celecoxib (HFa-Cel) or mesulid (HFa-Mes). Euglycemic hyperinsulinemic clamp (EHC) experiment was performed at the end of study. Another set of rats with similar grouping was further divided into those with a 4, 8, or 12-week intervention period for hepatic sampling. Body weight was increased significantly and similarly in HFa, HFa-Cel, and HFa-Mes. Time-dependent increases in plasma insulin, glucose, 8-isoprostanes, leptin levels, homeostasis model assessment of insulin resistance (HOMA-IR) and hepatic triglyceride contents shown in HFa were significantly reversed in HFa-Cel and HFa-Mes. During EHC period, the reduction in stimulation of whole body glucose uptake, suppression of hepatic glucose production and metabolic clearance rate of insulin shown in HFa were significantly reversed in HFa-Cel and HFa-Mes. The enhanced COX-2 and tumor necrosis factor-alpha (TNF-alpha) but attenuated PPAR-gamma and C/EBP-alpha mRNA expressions in epididymal fat shown in HFa were significantly reversed in HFa-Cel and HFa-Mes. The increases in average cell size of adipocytes and CD68 positive cells shown in HFa were also significantly reversed in HFa-Cel and HFa-Mes. Our findings suggest that COX-2 activation in fat inflammation is important in the development of insulin resistance and fatty liver in high fat induced obese rats.

Alpha 1-antitrypsin deficiency-associated panniculitis: case report and review of the literature

Alpha 1-antitrypsin is the primary serum proteinase inhibitor. Alpha 1-antitrypsin deficiency, especially the ZZ genotype, has been linked mainly to emphysema and cirrhosis; it is also associated with paniculitis. A case of alpha 1-AT-associated panniculitis was documented in a 13-year-old girl in whom a deficiency of the enzyme was known to be present from infancy. This is unusual, since alpha 1-AT panniculitis previously was described in older patients without prior knowledge of the duration of the deficiency. Our patient developed erythematous, subcutaneous nodules subsequent to trauma, which later developed into deep, painless ulcers. We report this case so that the condition may be suspected in patients with panniculitis. The diagnosis may be confirmed by measuring quantitative alpha 1-AT serum levels and by enzyme genotyping. The treatment of choice is dapsone.

SIRT3 (Sirtuin-3) Prevents Ang II (Angiotensin II)-Induced Macrophage Metabolic Switch Improving Perivascular Adipose Tissue Function

OBJECTIVE

Infiltrated macrophages actively promote perivascular adipose tissue remodeling and represent a dominant population in the perivascular adipose tissue microenvironment of hypertensive mice. However, the role of macrophages in initiating metabolic inflammation remains uncertain. SIRT3 (sirtuin-3), a NAD-dependent deacetylase, is sensitive to metabolic status and mediates adaptation responses. In this study, we investigated the role of SIRT3-mediated metabolic shift in regulating NLRP3 (Nod-like receptor family pyrin domain-containing 3) inflammasome activation. Approach and Results: Here, we report that Ang II (angiotensin II) accelerates perivascular adipose tissue inflammation and fibrosis, accompanied by NLRP3 inflammasome activation and IL (interleukin)-1β secretion in myeloid SIRT3 knockout (SIRT3-/-) mice. This effect is associated with adipose tissue mitochondrial dysfunction. In vitro studies indicate that the deletion of SIRT3 in bone marrow-derived macrophages induces IL-1β production by shifting the metabolic phenotype from oxidative phosphorylation to glycolysis. Mechanistically, SIRT3 deacetylates and activates PDHA1 (pyruvate dehydrogenase E1 alpha) at lysine 83, and the loss of SIRT3 leads to PDH activity decrease and lactate accumulation. Knocking down LDHA (lactate dehydrogenase A) or using carnosine, a buffer against lactic acid, attenuates IL-1β secretion. Furthermore, the blockade of IL-1β from macrophages into brown adipocytes restores thermogenic markers and mitochondrial oxygen consumption. Moreover, NLRP3 knockout (NLRP3-/-) mice exhibited reduced IL-1β production while rescuing the mitochondrial function of brown adipocytes and alleviating perivascular adipose tissue fibrosis.

CONCLUSIONS

SIRT3 represents a potential therapeutic target to attenuate NLRP3-related inflammation. Pharmacological targeting of glycolytic metabolism may represent an effective therapeutic approach.

Characterization of Eicosanoids Produced by Adipocyte Lipolysis: IMPLICATION OF CYCLOOXYGENASE-2 IN ADIPOSE INFLAMMATION

Excessive adipocyte lipolysis generates lipid mediators and triggers inflammation in adipose tissue. However, the specific roles of lipolysis-generated mediators in adipose inflammation remain to be elucidated. In the present study, cultured 3T3-L1 adipocytes were treated with isoproterenol to activate lipolysis and the fatty acyl lipidome of released lipids was determined by using LC-MS/MS. We observed that β-adrenergic activation elevated levels of approximately fifty lipid species, including metabolites of cyclooxygenases, lipoxygenases, epoxygenases, and other sources. Moreover, we found that β-adrenergic activation induced cyclooxygenase 2 (COX-2), not COX-1, expression in a manner that depended on activation of hormone-sensitive lipase (HSL) in cultured adipocytes and in the epididymal white adipose tissue (EWAT) of C57BL/6 mice. We found that lipolysis activates the JNK/NFκB signaling pathway and inhibition of the JNK/NFκB axis abrogated the lipolysis-stimulated COX-2 expression. In addition, pharmacological inhibition of COX-2 activity diminished levels of COX-2 metabolites during lipolytic activation. Inhibition of COX-2 abrogated the induction of CCL2/MCP-1 expression by β-adrenergic activation and prevented recruitment of macrophage/monocyte to adipose tissue. Collectively, our data indicate that excessive adipocyte lipolysis activates the JNK/NFκB pathway leading to the up-regulation of COX-2 expression and recruitment of inflammatory macrophages.

High expression of Dicer reveals a negative prognostic influence in certain subtypes of primary cutaneous T cell lymphomas

BACKGROUND

Aberrant expression of microRNAs (miRNAs) has been implicated in oncogenesis of various tumors and primary cutaneous T cell lymphomas. Dicer, a ribonuclease III-like enzyme is essential for miRNA processing.

OBJECTIVE

We initiated a retrospective study to characterize the alterations in the expression profile of Dicer in patients with primary cutaneous T cell lymphomas (CTCL).

METHODS

A total of 50 consecutive patients with primary CTCL were studied, with the majority having mycosis fungoides (n=34). Five patients had primary cutaneous CD 30+ anaplastic large cell lymphoma, four patients each had lymphomatoid papulosis and primary cutaneous CD4-positive small/medium T-cell lymphoma, one primary cutaneous γδ T cell lymphoma, one Sézary syndrome and another subcutaneous panniculitis-like T cell lymphoma of αβ-phenotype. Immunohistochemistry was performed on paraffin sections using a commercially available antibody against Dicer. Intensity of expression was correlated with clinical parameters including disease specific survival (DSS) and time to progression (TTP).

RESULTS

After a median follow-up of 74 months (range: 1-271), 12/50 patients (24%) have died. Univariate and multivariate analysis for disease-specific survival showed Dicer expression and stage as a negative predictive factor in the sole group of MF patients (n=34) as well as in the heterogeneous group of patients (n=50), but not gender, histological subtype, primary localization of disease, age and recurrence of lymphoma (p>0.05).

CONCLUSION

Our data suggest Dicer expression as a possible molecular marker in patients with MF and apparently indicate that miRNA(s) might be of clinical relevance in CTCL.

High-Fat Diet-Induced Adipose Tissue and Liver Inflammation and Steatosis in Mice Are Reduced by Inhibiting Sialidases

High-fat diet (HFD)-induced inflammation and steatosis of adipose tissue and liver are associated with a variety of serious health risks. Sialic acids are found as the distal terminal sugar on glycoproteins, which are removed by sialidases (neuraminidases). In humans and mice, pulmonary fibrosis is associated with up-regulation of sialidases, and injections of sialidase inhibitors attenuate bleomycin-induced pulmonary fibrosis. Sialidase levels are altered in obese rodents and humans. This report shows that for mice on an HFD, injections of the sialidase inhibitor N-acetyl-2,3-dehydro-2-deoxyneuraminic acid inhibit weight gain, reduce steatosis, and decrease adipose tissue and liver inflammation. Compared with control, mice lacking the sialidase neuraminidase 3 have reduced HFD-induced adipose tissue and liver inflammation. These data suggest that sialidases promote adipose and liver inflammation in response to a high-fat diet.

Clinical analysis of 10 cases with subcutaneous panniculitis-like T-cell lymphoma and tissue AURKA expression

BACKGROUND

Due to its rarity, subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is often misdiagnosed as benign panniculitis, and there are no standardized treatment guidelines for SPTCL. Aurora kinase A (AURKA) plays a regulatory role in both mitosis and meiosis. Cells treated with an AURKA inhibitor showed severe mitotic delay, which triggered apoptosis.

MATERIALS AND METHODS

Ten cases of SPTCL were collected in this study, and immunohistochemistry was performed to detect AURKA expression in the skin tissues of these cases. Control groups were set as follows: 1) 10 cases of inflammatory panniculitis; 2) 9 healthy individuals. Fisher's exact test was used to compare the positive rates of AURKA among various groups.

RESULTS

An average onset age of 27.3 years was found in 10 SPTCL cases. Clinically, these patients primarily presented with multiple subcutaneous nodules on the trunk and lower extremities, accompanied by intermittent high fever. One case showed lymph node metastasis, while no other distant organ metastasis being observed in any case. Pathologically, there was an infiltration of a large number of atypical lymphocytes within the fat lobules, characterized as a cytotoxic type. AURKA stanning was positive in 6 out of 10 SPTCL cases, while no positive cases were found in the control groups.

CONCLUSION

1) SPTCL predominantly affects young individuals and can be identified by nodular erythema on the trunk, intermittent high fever, and infiltration of atypical cytotoxic lymphocytes within fat lobules. 2) For early-stage cases without metastasis, monotherapy with glucocorticoids or immunosuppressants such as cyclosporine can be considered. 3) High expression of AURKA in SPTCL tissues suggests that AURKA could be a potential biomarker for disease diagnosis, providing a theoretical basis for further targeted therapy.

Subcutaneous fat necrosis associated with pancreatitis: histochemical and electron microscopic findings

Subcutaneous fat necrosis associated with pancreatitis has been postulated to be due to the effects of circulating pancreatic lipase. We report positive intracellular staining of adipocytes with a monoclonal antibody to pancreatic lipase in a lesion of subcutaneous pancreatic fat necrosis, and confirm the role of pancreatic lipase in the pathogenesis of this syndrome.

[Panniculitis associated with severe alpha 1-antitrypsin deficiency]

Genetically determined deficiency of alpha-1-antitrypsin, the primary serum protease inhibitor, can result in pulmonary emphysema or liver cirrhosis, and panniculitis may be an early symptom. A case of recurring panniculitis in a 29 year-old woman is described, which led to the diagnosis of severe alpha-1-antitrypsin deficiency (Pi ZZ). Serum alpha-1-antitrypsin levels should be measured in patients presenting with panniculitis.