| 1. |
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| 2. |
- Bentinger, Magnus, et al.
(författare)
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Influence of liver-X-receptor on tissue cholesterol, coenzyme Q and dolichol content
- 2012
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Ingår i: Molecular membrane biology. - : Informa UK Limited. - 0968-7688 .- 1464-5203. ; 29:7, s. 299-308
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Tidskriftsartikel (refereegranskat)abstract
- The organ content of the mevalonate pathway lipids was investigated in liver-X-receptor (LXR) alpha, beta and double knockout mice. An extensive or moderate increase of total cholesterol in the double KO mice was found in all organs elicited by the increase of the esterified form. In LXR alpha and double KO mice, coenzyme Q (CoQ) was decreased in liver and increased in spleen, thymus and lung, while dolichol was increased in all organs investigated. This effect was confirmed using LXR-agonist GW 3965. Analysis of CoQ distribution in organelles showed that the modifications are present in all cellular compartments and that the increase of the lipid in mitochondria was the result of a net increase of CoQ without changing the number of mitochondria. It appears that LXR influences not only cellular cholesterol homeostasis but also the metabolism of CoQ and dolichol, in an indirect manner.
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| 3. |
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| 4. |
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| 5. |
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| 6. |
- Catrina, Sergiu-Bogdan
(författare)
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Regulators of angiogenesis in diabetes and tumors
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Angiogenesis is tightly regulated in order to provide adequate supply of nutrients and oxygen for normal cellular function. Tissue oxygenation represents a balance between the requirement for oxygen to maintain the cellular energy level and the potential risk of cellular oxidative damage. The master regulator of oxygen homeostasis is Hypoxia inducible factor-1 (HIF-1). Our basic hypothesis was therefore that HIF modulation might be relevant for diseases characterised by dysregulated angiogenesis, such as diabetes mellitus and tumors. Chronic complications of diabetes are a major health problem, and a better understanding of their pathogenic mechanisms could offer a more rational therapy. Both hyperglycemia and hypoxia play important roles in the pathogenesis of diabetes complications and we propose that the interplay between these two factors is essential in determining the devellopement of chronic complications of diabetes. We demonstrated that high concentrations of glucose interfere with hypoxia-dependent stabilization of HIF-1alpha against proteasomal degradation in both primary human dermal fibroblasts and microvascular endothelial cells. The destabilizing effect of glucose was partially independent of prolyl hydroxylases (PHD). Hyperglycemia also inhibited transactivation and function of HIF-1 as demonstrated by a HRE (hypoxia responsive elements) reporter gene assay. In agreement with our in vitro observations we detect lower expression of HIF-1 alpha in diabetic wounds then in venous ulcers that share the same hypoxic environment but not the chronic exposure to hyperglycemia. Based on these findings we further investigated the potential therapeutic effect of HIF-1 alpha up-regulation in diabetic woundsby using DMOG, a chemical inducer of HIF-1 alpha which showed virtually no toxic effect on primary dermal fibroblasts in vitro. Local treatment with DMOG normalized the healing rate of experimental wounds in db/db mice suggesting that HIF-1 alpha modulation is a promising therapeutical approach for diabetic wounds. Dysregulated angiogenesis is also a hallmark of tumor diseases. Kaposi s sarcoma (KS) is a highly vascularised tumor, which depends strictly on angiogenetic stimuli. We have therefore investigated the HIF pathway in KS and its relation to the insulin like growth factor (IGF) system, known as a major factor in pathophysiology of different tumors. We demonstrated that KS cells express both HIF-1alpha and HIF-2 alpha even in normoxia and that IGF-I induced their expression, showing for the first time that a growth factor is able to induce accumulation of both HIFalpha congeners. HIF accumulation was followed by functional activation as demonstrated by a HRE reporter gene assay and by induction of HIF target genes (ex. VEGF). IGF-I induced accumulation of both HIF-1 alpha and HIF-2 alpha at a posttranscriptional level as demonstrated by qRT-PCR and cycloheximide chasing experiment and we suggest that IGF-I increased the translation of the alpha subunits. The clinical relevance of our findings was confirmed by the identification of high levels of both HIF isofoms in tumor cells in biopsies from patients with AIDS-related KS. It was further demonstrated that IGF-I and IGF-II are potent growth factors for KS cells and have an additive effect with VEGF. IGF-I receptor (IGF-IR) was identified as the receptor mediating the IGFs effect and we described an autocrine loop in KS cells in which IGF-II is the endogenous ligand for IGF-IR. Finally, it was demonstrated that blocking the IGF-IR with picropodophyllin, a recently described selective IGF-IR tyrosine phosphorylation inhibitor, induced apoptosis and decreased HIF accumulation and function in KS cells, suggesting a potential future therapeutic approach. In conclusion, HIF is an important factor both in chronic complications of diabetes and in vascular tumor KS. We have highlighted that glucose and IGF-I regulate HIF by other mechanisms than the classic hypoxic regulation. Finally it was demonstrated that modulation of HIF can be a successful approach for treatment of both diabetic wounds and KS.
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| 7. |
- Chang, Ya-Ting, et al.
(författare)
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Perlecan heparan sulfate deficiency impairs pulmonary vascular development and attenuates hypoxic pulmonary hypertension
- 2015
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Ingår i: Cardiovascular Research. - : Oxford University Press (OUP). - 0008-6363 .- 1755-3245. ; 107:1, s. 20-31
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Tidskriftsartikel (refereegranskat)abstract
- Aims Excessive vascular cell proliferation is an important component of pulmonary hypertension (PH). Perlecan is the major heparan sulfate (HS) proteoglycan in the vascular extracellular matrix. It binds growth factors, including FGF2, and either restricts or promotes cell proliferation. In this study, we have explored the effects of perlecan HS deficiency on pulmonary vascular development and in hypoxia-induced PH. Methods and results In normoxia, Hspg2(Delta 3/Delta 3) mice, deficient in perlecan HS, had reduced pericytes and muscularization of intra-acinar vessels. Pulmonary angiography revealed a peripheral perfusion defect. Despite these abnormalities, right ventricular systolic pressure (RVSP) and myocardial mass remained normal. After 4 weeks of hypoxia, increases in the proportion of muscularized vessels, RVSP, and right ventricular hypertrophy were significantly less in Hspg2(Delta 3/Delta 3) compared with wild type. The early phase of hypoxia induced a significantly lower increase in fibroblast growth factor receptor-1 (FGFR1) protein level and receptor phosphorylation, and reduced pulmonary artery smooth muscle cell (PASMC) proliferation in Hspg2(Delta 3/Delta 3). At 4 weeks, FGF2 mRNA and protein were also significantly reduced in Hspg2(Delta 3/Delta 3) lungs. Ligand and carbohydrate engagement assay showed that perlecan HS is required for HS-FGF2-FGFR1 ternary complex formation. In vitro, proliferation assays showed that PASMC proliferation is reduced by selective FGFR1 inhibition. PASMC adhesion to fibronectin was higher in Hspg2(Delta 3/Delta 3) compared with wild type. Conclusions Perlecan HS chains are important for normal vascular arborization and recruitment of pericytes to pulmonary vessels. Perlecan HS deficiency also attenuates hypoxia-induced PH, where the underlying mechanisms involve impaired FGF2/FGFR1 interaction, inhibition of PASMC growth, and altered cell-matrix interactions.
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| 8. |
- Dalin, Frida, 1984-, et al.
(författare)
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Clinical and immunological characteristics of Autoimmune Addison's disease : a nationwide Swedish multicenter study
- 2017
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : Oxford University Press. - 0021-972X .- 1945-7197. ; 102:2, s. 379-389
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Tidskriftsartikel (refereegranskat)abstract
- CONTEXT: Studies on clinical and immunological features of Autoimmune Addison's disease (AAD) are needed to understand the disease burden and increased mortality.OBJECTIVE: To provide upgraded data on autoimmune comorbidities, replacement therapy, autoantibody profiles and cardiovascular risk factors.DESIGN, SETTING AND PARTICIPANTS: Cross sectional, population-based study. 660 AAD patients were included utilizing the Swedish Addison Registry (SAR) 2008-2014. When analyzing cardiovascular risk factors, 3,594 individuals from the population-based survey in Northern Sweden, MONICA (MONItoring of Trends and Determinants of CArdiovascular Disease), served as controls.MAIN OUTCOME MEASURE: Prevalence of autoimmune comorbidities and cardiovascular risk factors. Autoantibodies against 13 autoantigens were determined.RESULTS: Sixty percent of the SAR cohort consisted of females. Mean age at diagnosis was significantly higher for females than for males (36.8 vs. 31.1 years). The proportion of 21-hydroxylase autoantibody positive patients was 83% and 62% of patients had one or more associated autoimmune diseases, more frequently coexisting in females (p<0.0001). AAD patients had lower BMI (p<0.0001) and prevalence of hypertension (p=0.027) compared with controls. Conventional hydrocortisone tablets were used by 89% of patients; with the mean dose 28.1±8.5 mg/day. The mean hydrocortisone equivalent dose normalized to body surface was 14.8±4.4 mg/m(2)/day. Higher hydrocortisone equivalent dose was associated with higher incidence of hypertension (p=0.046).CONCLUSIONS: Careful monitoring of AAD patients is warranted to detect associated autoimmune diseases. Contemporary Swedish AAD patients do not have increased prevalence of overweight, hypertension, T2DM or hyperlipidemia. However, high glucocorticoid replacement doses may be a risk factor for hypertension.
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| 9. |
- dos Santos, Klinsmann Carolo, et al.
(författare)
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The impact of macronutrient composition on metabolic regulation : An Islet-Centric view
- 2022
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Ingår i: Acta Physiologica. - : Wiley. - 1748-1708 .- 1748-1716. ; 236:4
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Tidskriftsartikel (refereegranskat)abstract
- Aim: The influence of dietary carbohydrates and fats on weight gain is inconclusively understood. We studied the acute impact of these nutrients on the overall metabolic state utilizing the insulin:glucagon ratio (IGR). Methods: Following in vitro glucose and palmitate treatment, insulin and glucagon secretion from islets isolated from C57Bl/6J mice was measured. Our human in vivo study included 21 normoglycaemia (mean age 51.9 ± 16.5 years, BMI 23.9 ± 3.5 kg/m2, and HbA1c 36.9 ± 3.3 mmol/mol) and 20 type 2 diabetes (T2D) diagnosed individuals (duration 12 ± 7 years, mean age 63.6 ± 4.5 years, BMI 29.1 ± 2.4 kg/m2, and HbA1c 52.3 ± 9.5 mmol/mol). Individuals consumed a carbohydrate-rich or fat-rich meal (600 kcal) in a cross-over design. Plasma insulin and glucagon levels were measured at −30, −5, and 0 min, and every 30 min until 240 min after meal ingestion. Results: The IGR measured from mouse islets was determined solely by glucose levels. The palmitate-stimulated hormone secretion was largely glucose independent in the analysed mouse islets. The acute meal tolerance test demonstrated that insulin and glucagon secretion is dependent on glycaemic status and meal composition, whereas the IGR was dependent upon meal composition. The relative reduction in IGR elicited by the fat-rich meal was more pronounced in obese individuals. This effect was blunted in T2D individuals with elevated HbA1c levels. Conclusion: The metabolic state in normoglycaemic individuals and T2D-diagnosed individuals is regulated by glucose. We demonstrate that consumption of a low carbohydrate diet, eliciting a catabolic state, may be beneficial for weight loss, particularly in obese individuals.
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| 10. |
- Elksnis, Andris, 1993-
(författare)
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Pharmaceutical Protection of Beta-Cells in Diabetes : Using Tyrosine Kinase Inhibition and NOX4 Inhibitors
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Diabetes mellitus is a complex and heterogenous disease, with loss of beta-cell function and mass being a characteristic of not only type 1 diabetes (T1D), but also type 2 diabetes (T2D). In T1D, inappropriate inflammatory signaling is thought to participate in the autoimmune suppression and destruction of beta-cells. In T2D progressive insulin resistance with resulting glucolipotoxicity, increased inflammation and oxidative stress, drives islet amyloid formation and subsequent beta-cell exhaustion and failure. Even under best managed care, disease progression and eventual complications are unavoidable. New interventions that aim to improve beta-cell survival are highly needed. This thesis investigates two such possible interventions: the tyrosine kinase inhibitor Imatinib, and selective NADPH-oxidase inhibition.Imatinib mesylate, used in treatment of chronic myeloid leukemia and other malignancies, was soon after its introduction reported to possess anti-diabetic properties in both T1D and T2D patients undergoing treatment. Imatinib has been shown to prevent and reverse diabetes in NOD mice and improve glucose tolerance in high fat diet treated rats. In paper I, we aimed to characterize the mechanisms by which imatinib protects beta-cells. We found that imatinib inhibits complex I and II of the respiratory chain, leading to improved beta-cell survival through AMPK activation, reduced amyloid formation and protection against TXNIP upregulation.Oxidative stress may play a pivotal role in the development of beta-cell dysfunction and failure in T2D. The NADPH-oxidases are a family of 7 enzymes (NOX1-5 and DUOX 1-2), that produce reactive oxygen species that are important in various physiological processes but may, if excessively activated, also be a source for oxidative stress in T2D. In paper II, we evaluate novel selective NOX inhibitors as protective agents against in vitro induced human beta-cell stress. Selective NOX4 inhibition protected beta-cells against both cytokines and high-glucose + palmitate. In paper III we found that NOX4 inhibition increased mitochondrial membrane potential, mitochondrial reactive oxygen species and ATP/ADP ratio in a human beta-cell line, and this was paralleled with protection against human islet cell death when challenged with high-glucose and palmitate. Finally, in paper IV, we attempt to apply these findings in vivo, by transplanting athymic diabetic mice with human islets and treating them with a NOX4 inhibitor over a period of 4 weeks. Treated mice achieved lower blood glucose levels and water consumption throughout the treatment period, and apoptotic rates of insulin-positive human cells, measured as co-localization of insulin and cleaved caspase-3, were greatly reduced.
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| 11. |
- Eriksson, Daniel, et al.
(författare)
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Cytokine Autoantibody Screening in the Swedish Addison Registry Identifies Patients With Undiagnosed APS1
- 2018
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Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 103:1, s. 179-186
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Tidskriftsartikel (refereegranskat)abstract
- Context: Autoimmune polyendocrine syndrome type 1 (APS1) is a monogenic disorder that features autoimmune Addison disease as a major component. Although APS1 accounts for only a small fraction of all patients with Addison disease, early identification of these individuals is vital to prevent the potentially lethal complications of APS1.Objective: To determine whether available serological and genetic markers are valuable screening tools for the identification of APS1 among patients diagnosed with Addison disease.Design: We systematically screened 677 patients with Addison disease enrolled in the Swedish Addison Registry for autoantibodies against interleukin-22 and interferon-α4. Autoantibody-positive patients were investigated for clinical manifestations of APS1, additional APS1-specific autoantibodies, and DNA sequence and copy number variations of AIRE.Results: In total, 17 patients (2.5%) displayed autoantibodies against interleukin-22 and/or interferon-α4, of which nine were known APS1 cases. Four patients previously undiagnosed with APS1 fulfilled clinical, genetic, and serological criteria. Hence, we identified four patients with undiagnosed APS1 with this screening procedure.Conclusion: We propose that patients with Addison disease should be routinely screened for cytokine autoantibodies. Clinical or serological support for APS1 should warrant DNA sequencing and copy number analysis of AIRE to enable early diagnosis and prevention of lethal complications.
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| 12. |
- Falhammar, Henrik, et al.
(författare)
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Riedel's thyroiditis : clinical presentation, treatment and outcomes
- 2018
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Ingår i: Endocrine. - : Humana Press. - 1355-008X .- 1559-0100. ; 60:1, s. 185-192
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Riedel´s thyroiditis (RT) is a rare inflammatory disease of the thyroid gland, causing compression and fibrosis of adjacent tissues. Typically the goiter is hard and firm. Hoarseness, dyspnea, and dysphagia may be present.METHODS: We retrospectively reviewed all patients known by us with RT in addition to all patients with appropriate ICD-10 codes evaluated at the Karolinska University Hospital 2003-2015. Clinical, biochemical, and histological data of patients with RT were recorded in detail. Histological preparations were re-examined when available.RESULTS: RT was diagnosed in six patients. Five were females and the median age at first presentation was 50 years (25-81 years). Median follow-up time was 3.75 years (1-22 years). At diagnosis five had hypothyroidism. Four had extrathyroidal manifestations, and one of these had also distant fibrosis. One patient had a clear IgG4/IgG ratio over 40%. One patient was treated with tracheostomy, one with isthmectomy and one with total thyroidectomy. Four had been treated with glucocorticoids, four with tamoxifen, and two with both drugs. One had also been treated with mycophenolate mofetil combined with Rituximab. At the end of follow-up four was doing fine, one had recurrent episodes of inflammation and one had died of possible complications to RT.CONCLUSION: It is important to recognize RT and give adequate treatment. Steroids are still the mainstay of therapy but other medications against fibrosclerosis can be considered. Wakefulness of other fibrosing manifestations is essential. Immunohistochemistry can show whether IgG-4 plasma cells are increased which could lead to fibrosis in other organs.
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| 13. |
- Keindl, Magdalena, et al.
(författare)
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Increased Plasma Soluble Interleukin-2 Receptor Alpha Levels in Patients With Long-Term Type 1 Diabetes With Vascular Complications Associated With IL2RA and PTPN2 Gene Polymorphisms
- 2020
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Ingår i: Frontiers in Endocrinology. - : Frontiers Media S.A.. - 1664-2392. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Type 1 diabetes (T1D) is largely considered an autoimmune disease leading to the destruction of insulin-producing pancreatic beta cells. Further, patients with T1D have 3-4-fold increased risk of developing micro- and macrovascular complications. However, the contribution of immune-related factors contributing to these diabetes complications are poorly understood. Individuals with long-term T1D who do not progress to vascular complications offer a great potential to evaluate end-organ protection. The aim of the present study was to investigate the association of inflammatory protein levels with vascular complications (retinopathy, nephropathy, cardiovascular disease) in individuals with long-term T1D compared to individuals who rapidly progressed to complications. We studied a panel of inflammatory markers in plasma of patients with long-term T1D with (n = 81 and 26) and without (n = 313 and 25) vascular complications from two cross-sectional Scandinavian cohorts (PROLONG and DIALONG) using Luminex technology. A subset of PROLONG individuals (n = 61) was screened for circulating immune cells using multicolor flow cytometry. We found that elevated plasma levels of soluble interleukin-2 receptor alpha (sIL-2R) were positively associated with the complication phenotype. Risk carriers of polymorphisms in the IL2RA and PTPN2 gene region had elevated plasma levels of sIL-2R. In addition, cell surface marker analysis revealed a shift from naive to effector T cells in T1D individuals with vascular complications as compared to those without. In contrast, no difference between the groups was observed either in IL-2R cell surface expression or in regulatory T cell population size. In conclusion, our data indicates that IL2RA and PTPN2 gene variants might increase the risk of developing vascular complications in people with T1D, by affecting sIL-2R plasma levels and potentially lowering T cell responsiveness. Thus, elevated sIL-2R plasma levels may serve as a biomarker in monitoring the risk for developing diabetic complications and thereby improve patient care.
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| 14. |
- Li, Dongqing, et al.
(författare)
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MicroRNA-132 enhances transition from inflammation to proliferation during wound healing.
- 2015
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Ingår i: Journal of Clinical Investigation. - 0021-9738 .- 1558-8238. ; 125:8, s. 3008-26
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Tidskriftsartikel (refereegranskat)abstract
- Wound healing is a complex process that is characterized by an initial inflammatory phase followed by a proliferative phase. This transition is a critical regulatory point; however, the factors that mediate this process are not fully understood. Here, we evaluated microRNAs (miRs) in skin wound healing and characterized the dynamic change of the miRNome in human skin wounds. miR-132 was highly upregulated during the inflammatory phase of wound repair, predominantly expressed in epidermal keratinocytes, and peaked in the subsequent proliferative phase. TGF-β1 and TGF-β2 induced miR-132 expression in keratinocytes, and transcriptome analysis of these cells revealed that miR-132 regulates a large number of immune response- and cell cycle-related genes. In keratinocytes, miR-132 decreased the production of chemokines and the capability to attract leukocytes by suppressing the NF-κB pathway. Conversely, miR-132 increased activity of the STAT3 and ERK pathways, thereby promoting keratinocyte growth. Silencing of the miR-132 target heparin-binding EGF-like growth factor (HB-EGF) phenocopied miR-132 overexpression in keratinocytes. Using mouse and human ex vivo wound models, we found that miR-132 blockade delayed healing, which was accompanied by severe inflammation and deficient keratinocyte proliferation. Together, our results indicate that miR-132 is a critical regulator of skin wound healing that facilitates the transition from the inflammatory to the proliferative phase.
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| 15. |
- Li, Dongqing, et al.
(författare)
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miR-19a/b and miR-20a promote wound healing by regulating the inflammatory response of keratinocytes
- 2021
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Ingår i: Journal of Investigative Dermatology. - : Elsevier. - 0022-202X .- 1523-1747. ; 141:3, s. 659-671
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Tidskriftsartikel (refereegranskat)abstract
- Persistent and impaired inflammation impedes tissue healing and is characteristic of chronic wounds. A better understanding of the mechanisms controlling wound inflammation is needed. Here we show that in human wound-edge keratinocytes, the expression of miR-17, miR-18a, miR-19a, miR-19b, and miR-20a, which all belong to the miR-17∼92 cluster, is upregulated during wound repair. However, their levels are lower in chronic ulcers than acute wounds at the proliferative phase. Conditional knockout of miR-17∼92 in keratinocytes as well as injection of miR-19a/b and miR-20a antisense inhibitors into wound-edges enhanced inflammation and delayed wound closure in mice. In contrast, conditional overexpression of the miR-17∼92 cluster or miR-19b alone in mice keratinocytes accelerated wound closure in vivo. Mechanistically, miR-19a/b and miR-20a decreased TLR3-mediated NF-κB activation by targeting SHCBP1 and SEMA7A, respectively, reducing the production of inflammatory chemokines/cytokines by keratinocytes. Thus, as crucial regulators of wound inflammation, lack of miR-19a/b and miR-20a may contribute to sustained inflammation and impaired healing in chronic wounds. In line with this, we show that a combinatory treatment with miR-19b and miR-20a improved wound healing in a mouse model of type 2 diabetes.
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| 16. |
- Li, Xi, et al.
(författare)
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MicroRNA-132 with Therapeutic Potential in Chronic Wounds.
- 2017
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Ingår i: Journal of Investigative Dermatology. - : Elsevier BV. - 0022-202X .- 1523-1747. ; 137:12, s. 2630-2638
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Tidskriftsartikel (refereegranskat)abstract
- Chronic wounds represent a major and rising health and economic burden worldwide. There is a continued search toward more effective wound therapy. We found significantly reduced microRNA-132 (miR-132) expression in human diabetic ulcers compared with normal skin wounds and also in skin wounds of leptin receptor-deficient (db/db) diabetic mice compared with wild-type mice. Local replenishment of miR-132 in the wounds of db/db mice accelerated wound closure effectively, which was accompanied by increased proliferation of wound edge keratinocytes and reduced inflammation. The pro-healing effect of miR-132 was further supported by global transcriptome analysis, which showed that several inflammation-related signaling pathways (e.g., NF-κB, NOD-like receptor, toll-like receptor, and tumor necrosis factor signaling pathways) were the top ones regulated by miR-132 in vivo. Moreover, we topically applied liposome-formulated miR-132 mimics mixed with pluronic F-127 gel on human ex vivo skin wounds, which promoted re-epithelialization. Together, our study showed the therapeutic potential of miR-132 in chronic wounds, which warrants further evaluation in controlled clinical trials.
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| 17. |
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| 18. |
- Wang, Sailan, et al.
(författare)
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Rare coding variants in NOX4 link high ROS levels to psoriatic arthritis mutilans
- 2024
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Ingår i: EMBO Molecular Medicine. - : EMBO Press. - 1757-4676 .- 1757-4684. ; 16:3, s. 596-615
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Tidskriftsartikel (refereegranskat)abstract
- Psoriatic arthritis mutilans (PAM) is the rarest and most severe form of psoriatic arthritis, characterized by erosions of the small joints and osteolysis leading to joint disruption. Despite its severity, the underlying mechanisms are unknown, and no susceptibility genes have hitherto been identified. We aimed to investigate the genetic basis of PAM by performing massive parallel sequencing in sixty-one patients from the PAM Nordic cohort. We found rare variants in the NADPH oxidase 4 (NOX4) in four patients. In silico predictions show that the identified variants are potentially damaging. NOXs are the only enzymes producing reactive oxygen species (ROS). NOX4 is specifically involved in the differentiation of osteoclasts, the cells implicated in bone resorption. Functional follow-up studies using cell culture, zebrafish models, and measurement of ROS in patients uncovered that these NOX4 variants increase ROS levels both in vitro and in vivo. We propose NOX4 as the first candidate susceptibility gene for PAM. Our study links high levels of ROS caused by NOX4 variants to the development of PAM, offering a potential therapeutic target.
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| 19. |
- Yang, Jiangning, et al.
(författare)
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Hypoxic erythrocytes mediate cardioprotection through activation of soluble guanylate cyclase and release of cyclic GMP
- 2023
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Ingår i: Journal of Clinical Investigation. - : American Society For Clinical Investigation. - 0021-9738 .- 1558-8238. ; 133:17
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Tidskriftsartikel (refereegranskat)abstract
- Red blood cells (RBCs) mediate cardioprotection via nitric oxide-like bioactivity, but the signaling and the identity of any mediator released by the RBCs remains unknown. We investigated whether RBCs exposed to hypoxia release a cardioprotective mediator and explored the nature of this mediator. Perfusion of isolated hearts subjected to ischemia-reperfusion with extracellular supernatant from mouse RBCs exposed to hypoxia resulted in improved postischemic cardiac function and reduced infarct size. Hypoxia increased extracellular export of cyclic guanosine monophosphate (cGMP) from mouse RBCs, and exogenous cGMP mimicked the cardioprotection induced by the supernatant. The protection induced by hypoxic RBCs was dependent on RBC-soluble guanylate cyclase and cGMP transport and was sensitive to phosphodiesterase 5 and activated cardiomyocyte protein kinase G. Oral administration of nitrate to mice to increase nitric oxide bioactivity further enhanced the cardioprotective effect of hypoxic RBCs. In a placebo-controlled clinical trial, a clear cardioprotective, soluble guanylate cyclase-dependent effect was induced by RBCs collected from patients randomized to 5 weeks nitrate-rich diet. It is concluded that RBCs generate and export cGMP as a response to hypoxia, mediating cardioprotection via a paracrine effect. This effect can be further augmented by a simple dietary intervention, suggesting preventive and therapeutic opportunities in ischemic heart disease.
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| 20. |
- Zheng, Xiaowei, et al.
(författare)
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Repression of hypoxia-inducible factor-1 contributes to increased mitochondrial reactive oxygen species production in diabetes
- 2022
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Ingår i: eLIFE. - : eLife Sciences Publications Ltd. - 2050-084X. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Background: Excessive production of mitochondrial reactive oxygen species (ROS) is a central mechanism for the development of diabetes complications. Recently, hypoxia has been identified to play an additional pathogenic role in diabetes. In this study, we hypothesized that ROS overproduction was secondary to the impaired responses to hypoxia due to the inhibition of hypoxia-inducible factor-1 (HIF-1) by hyperglycemia. Methods: The ROS levels were analyzed in the blood of healthy subjects and individuals with type 1 diabetes after exposure to hypoxia. The relation between HIF-1, glucose levels, ROS production and its functional consequences were analyzed in renal mIMCD-3 cells and in kidneys of mouse models of diabetes. Results: Exposure to hypoxia increased circulating ROS in subjects with diabetes, but not in subjects without diabetes. High glucose concentrations repressed HIF-1 both in hypoxic cells and in kidneys of animals with diabetes, through a HIF prolyl-hydroxylase (PHD)-dependent mechanism. The impaired HIF-1 signaling contributed to excess production of mitochondrial ROS through increased mitochondrial respiration that was mediated by Pyruvate dehydrogenase kinase 1 (PDK1). The restoration of HIF-1 function attenuated ROS overproduction despite persistent hyperglycemia, and conferred protection against apoptosis and renal injury in diabetes. Conclusions: We conclude that the repression of HIF-1 plays a central role in mitochondrial ROS overproduction in diabetes and is a potential therapeutic target for diabetic complications. These findings are timely since the first PHD inhibitor that can activate HIF-1 has been newly approved for clinical use. Funding: This work was supported by grants from the Swedish Research Council, Stockholm County Research Council, Stockholm Regional Research Foundation, Bert von Kantzows Foundation, Swedish Society of Medicine, Kung Gustaf V:s och Drottning Victorias Frimurarestifelse, Karolinska Institute's Research Foundations, Strategic Research Programme in Diabetes, and Erling-Persson Family Foundation for S-B.C.; grants from the Swedish Research Council and Swedish Heart and Lung Foundation for T.A.S.; and ERC consolidator grant for M.M.
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