| 1. |
- Bivik, Cecilia, 1978-
(författare)
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Regulation of UV induced apoptosis in human melanocytes
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Malignant melanoma arises from the pigment producing melanocytes in epidermis and is the most aggressive type of skin cancer. The incidence of malignant melanoma is increasing faster than any other type of cancer in white population worldwide, with a doubling rate every 10-20 years. So far, the only identified external risk factor for malignant melanoma is UV exposure. Elimination of photodamaged cells by apoptosis (programmed cell death) is essential to prevent tumor formation. Melanocytes are considered relatively resistant to apoptosis, however, the regulation of apoptosis in melanocytes is still unknown.The aim of this thesis was to investigate the apoptotic process following ultraviolet (UV) irradiation in primary cultures of human melanocytes. Focus was on regulation of mitochondrial stability by Bcl-2 family proteins and the possible participation of lysosomal proteases, cathepsins. UV irradiation activated the mitochondrial pathway of apoptosis, leading to cytochrome c release, caspase activation, and nuclear fragmentation. No change in protein expression of Bax and Bcl-2 was observed in response to UV. Instead, translocation of the Bcl-2 family proteins from cytosol to mitochondia was important in the regulation of survival and death of melanocytes. The findings further demonstrated permeabilization of the lysosomal membrane to occur early in the apoptotic process, resulting in cathepsin release into the cytosol. The cathepsins were potent pro-apoptotic mediators and triggered apoptosis upstream of Bax translocation and mitochondrial membrane permeabilization. In response to both heat and UV irradiation, there was a marked increase in expression of stress-induced heat shock protein 70 (Hsp70), which inhibited apoptosis by binding lysosomal and mitochondrial membranes and counteracting the release of cathepsins and cytochrome c. Furthermore, UV irradiation activated c-jun N-terminal kinase (JNK), which triggered apoptosis upstream of cathepsins release from the lysosomes. In addition, JNK mediated apoptosis through phosphorylation of pro-apoptotic Bim, which was released from anti-apoptotic Mcl-1, by UV induced Mcl-1 depletion.This thesis illustrates that permeabilization of mitochondria and lysosomes and release of their constituents to the cytosol participates in UV induced apoptosis signaling in human melanocytes in vitro. The process is regulated by a complex network of pro- and anti-apoptotic proteins, exerting their effects through intracellular translocation and alteration of protein expression.
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| 2. |
- Ekman, Anna-Karin, et al.
(författare)
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Overexpression of Psoriasin (S100A7) Contributes to Dysregulated Differentiation in Psoriasis.
- 2017
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Ingår i: Acta Dermato-Venereologica. - : Society for the Publication of Acta Dermato - Venereologica. - 0001-5555 .- 1651-2057. ; 97:4, s. 441-448
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Tidskriftsartikel (refereegranskat)abstract
- Psoriasin, which is highly expressed in psoriasis, is encoded by a gene located within the epidermal differentiation complex. The aim of this study was to investigate the effect of endogenous psoriasin on disturbed keratinocyte differentiation in psoriasis. Immunohistochemical staining revealed a gradient of psoriasin expression in the psoriatic epidermis with highest expression in the suprabasal, differentiated layers. Induction of keratinocyte differentiation caused concurrent expression of psoriasin and the differentiation marker involucrin. The differentiation-induced psoriasin expression was found to be mediated by the protein kinase C pathway. The downregulation of psoriasin expression by small interfering RNA revealed that psoriasin mediates the expression of involucrin, desmoglein 1, transglutaminase 1 and CD24 in normal differentiation. The lentivirus-mediated overexpression of psoriasin, mimicking the psoriatic milieu, gave rise to an altered regulation of differentiation genes and an expression pattern reminiscent of that in psoriatic epidermis. These findings suggest that psoriasin contributes to the dysregulated differentiation process in the psoriasis epidermis.
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| 3. |
- Sigurdardottir, Gunnthorunn, 1975-
(författare)
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Studies of the Systemic Inflammation in Psoriasis
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Psoriasis is a common immune-mediated disease, where an increased prevalence of extra cutaneous diseases and mortality is observed. Common inflammatory mechanisms are implicated. The general aim of this thesis was to investigate markers of inflammation and cardiovascular disease in psoriasis, now considered a systemic disease, assumed to reflect the systemic inflammation.In Study I, Th1-, Th2- and Th17-associated chemokines were elevated in the blood of psoriasis patients in comparison to controls and, in Study II, six markers of cardiovascular risk were demonstrated to be systemically elevated. After adjustment for body mass index and waist: hip ratio in Study II, only one marker, the total plasminogen activator inhibitor-1, showed sustained elevated levels. The levels of the chemokines and the cardiovascular markers were unaffected after treatment with narrowband UVB therapy (NB-UVB), despite a significant improvement in skin lesions, indicating more local than systemic effects of NBUVB. This was further strengthened by the fact that the response to in-vitro stimulation in the peripheral blood mononuclear cells (PBMCs) of psoriasis patients before and after NB-UVB treatment was unaffected. In Study I, CCL20 was shown to correlate to the psoriasis area severity index (PASI), but this correlation was lost after phototherapy, suggesting sources of CCL20 other than the skin. Conversely, systemic treatment with TNF-α inhibition in Study II alleviated the elevated systemic levels of the cardiovascular risk markers. In Study III, the levels of 17 potential biomarkers, with the emphasis on endothelial and adipocyte dysfunction, soluble receptors and the innate mechanisms were studied. Endocan-1, CXCL16, and sVEGFR1, were found to be systemically decreased in psoriasis patients at baseline. Endocan-1 showed a negative correlation to the PASI. In contrast to the results in Studies I and II, NB-UVB therapy affected the systemic levels of investigated markers; Endocan-1 and CXCL16 were restored to normal levels, while sVEGF1, FABP3, FABP4 and sIL-1R1 showed a significant reduction following NB-UVB. In Study IV, the focus was on the contribution of innate immune mechanisms and the effects of the cytokines IL-17 and TNF-α on systemic inflammation. In keratinocytes, the gene and protein expression of inflammasome components was increased upon exposure to IL-17 and TNF-α. Systemically, the constitutive expression of the inflammasome components NLRP1, NLRP3 and AIM2 was detected in neutrophils, classical monocytes, CD4+ lymphocytes and B-cell subsets from psoriasis patients. Upon exposure to IL-17 and TNF-α, increased systemic caspase-1 levels were detected, confirming systemic inflammasome activity.In conclusion, these studies support the hypothesis that there is a systemic inflammation in psoriasis to which both innate and adaptive immune mechanisms contribute. The systemic inflammation may be explained, to some extent, but not completely, by body weight and fat distribution. The different effects of NB-UVB therapy on the systemic levels of the investigated markers may reflect their different roles in psoriasis, but the ameliorating effects of the TNF-α inhibitor on the elevated cardiovascular markers suggests that systemic treatment should be evaluated in psoriasis patients with signs of a systemic inflammatory burden.
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| 4. |
- Verma, Deepti, 1969-, et al.
(författare)
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Enhanced Inflammasome Activity in Patients with Psoriasis Promotes Systemic Inflammation
- 2021
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Ingår i: Journal of Investigative Dermatology. - : Elsevier. - 0022-202X .- 1523-1747. ; 141:3, s. 586-595.e5
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Tidskriftsartikel (refereegranskat)abstract
- Psoriasis is linked to systemic inflammation and cardiovascular comorbidities, but studies of the underlying cellular mechanisms are lacking. The NLRP3 inflammasome is genetically associated with psoriasis, and its activation is increasingly linked with cardiovascular disease. In this study, we show that patients with psoriasis exhibited higher plasma levels of inflammasome-generated IL-1ß and IL-18, without any correlation to skin lesion severity. Increased constitutive expression of the inflammasome sensors NLRP3, NLRP1, and AIM2 was found in peripheral blood cells of the patients and also of those with mild disease, and this was accompanied by an increased caspase-1 reactivity in the myeloid blood subsets. TNF-a was found to activate selectively the NLRP3 inflammasome without the requirement for a priming signal. TNF-a was found to signal through the TNFR?caspase-8?caspase-1 alternative inflammasome pathway, which proceeds independently of pyroptosis. Patients who received anti-TNF therapy had normalized plasma IL-1ß and IL-18 levels as well as normalized caspase-1 reactivity. This was in contrast to the patients treated with methotrexate who exhibited persistent, increased caspase-1 reactivity. Thus, we show that the TNF-a-mediated activation of NLRP3 inflammasomes in patients with psoriasis may contribute to systemic inflammation. Anti-TNF therapy normalized inflammasome function, suggesting a mechanism for the cardiovascular risk?reducing effect.
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