| 1. |
- Fallah, Mahsa, 1986-
(författare)
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Plasminogen : a pleiotropic inflammatory regulator in radiation-induced wound formation and wound repair
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The plasminogen activator (PA) system plays important roles in many physiological and pathological processes, including inflammation and wound healing. Plasmin, the central component of the PA system, is a broad-spectrum serine protease that is derived from its inactive precursor form, plasminogen. The first aim of this thesis was to study the role of plasminogen in the formation of radiation-induced wounds, which are an inflammatory side effect of radiotherapy. The second aim was to investigate the molecular mechanisms behind the potentiating effect of plasminogen in the healing of radiation-induced wounds. The third aim was to explore the therapeutic potential of plasminogen in the healing of radiation-induced wounds.Radiation therapy in cancer patients is often limited by side effects such as radiation-induced skin damage (radiodermatitis). The mechanisms behind the formation of radiodermatitis are not fully elucidated, and there are no effective preventive therapies for clinical use. In this study, we show that irradiation of skin in WT (wild-type) mice induces plasminogen accumulation, which is followed by activation of TGF-β (transforming growth factor-beta) signaling and the development of inflammation that leads to skin damage. However, plasminogen-deficient mice and mice lacking PAs were mostly resistant to radiodermatitis. Moreover, treatment with a plasminogen inhibitor, tranexamic acid, decreases radiodermatitis in WT mice and prevented radiodermatitis in heterozygous mice. Thus, plasmin is required for the formation of radiodermatitis, and inhibition of plasminogen activation might be a novel treatment strategy to reduce or prevent radiodermatitis in patients undergoing radiotherapy.Wound healing consists of partially overlapping inflammatory, proliferation, and tissue remodeling phases, and failure to terminate inflammation leads to the formation of chronic wounds. Previous studies by our group have shown that plasminogen is transported to acute wounds by inflammatory cells where it potentiates inflammation and enhances wound healing. Here, we report that plasminogen-deficient mice, which have delayed wound healing, have extensive fibrin and neutrophil depositions in the wounded area long after re-epithelialization, indicating inefficient debridement and chronic inflammation. The delayed formation of granulation tissue suggests that fibroblast function is also impaired in the absence of plasminogen. Therefore, in addition to its role in the activation of inflammation, plasminogen is also crucial for the resolution of inflammation and the activation of the proliferation phase. Importantly, supplementation of plasminogen-deficient mice with human plasminogen leads to a restored healing capacity that is comparable to that in WT mice. Therefore, plasminogen might be an important future therapeutic agent for treatment of wounds.In radiation-induced wounds, inflammation often cannot resolve and the wounds become chronic and fibrotic. Currently, there is no gold standard for the treatment of radiation-induced wounds. In this study, we have shown that radiation-induced wounds treated with plasminogen healed faster than placebo-treated wounds, had diminished inflammation and granulation tissue formation, and had enhanced re-epithelialization and collagen maturation. Transcriptome analysis showed that plasminogen has a pleiotropic effect on gene expression during wound healing, influencing the expression of 33 genes out of the 84 genes studied. In particular, plasminogen decreased the expression of 11 pro-inflammatory genes early in the healing process. Later, plasminogen decreased WNT (Wingless/Integrated) and TGF-β signaling, as well as the expression of 5 growth factors and 13 factors involved in granulation tissue formation. From the genes downregulated by plasminogen, 19 genes are known to be involved in fibrosis. These results show that in radiation-induced wounds with excessive inflammation and tissue formation plasminogen is able to direct the healing process to a normal outcome without the risk for developing fibrosis. This makes plasminogen an attractive drug candidate for treating radiodermatitis in cancer patients. Taken together, our results indicate that plasminogen is a pleiotropic inflammatory regulator involved in radiation-induced wound formation as well as in wound repair.
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| 2. |
- Hansson, Annika, 1979-
(författare)
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The effects of plasminogen deficiency on the healing of tympanic membrane perforations
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The healing of tympanic membrane (TM) perforations is a complex wound healing process including inflammation, migration of keratinocytes and tissue remodelling. Most TM perforations in human heal spontaneously, however some perforations become chronic, and the reason to why is still largely unknown. In cutaneous wound healing plasminogen (plg) has been shown to play an important role. Plg is converted into the protease plasmin regulated by two plasminogen activators (PA), urokinase type PA (uPA) and tissue-type PA (tPA). The aim of the present thesis was to evaluate the role of plg in healing of TM perforations, both in vivo and in vitro. The main objectives were to determine the healing capacity of the TM, the involvement of keratinocytes, fibrin(ogen) and inflammatory cells in the healing process. The studies were performed in plg deficient and uPA deficient mice, with littermate wild type (wt) mice as controls It was shown that myringotomies of the TMs in plg deficient mice still remained open 143 days following a perforation. The wound area was characterized by an abundant recruitment and accumulation of inflammatory cells; mainly macrophages and neutrophils, an arrested keratinocyte migration and a fibrin deposition covering the surface of the TM. The TM perforations in the wt mice all healed within 11 days. Interestingly, the myringotomies of the plg deficient mice could be closed by reconstitution with systemic injections of plg, whereas injections of PBS had no affect on the healing. To characterize mechanisms involved in the development of persistent TM perforations in plg deficient mice after a myringotomy the early inflammatory response during the first 48 hours was studied. The recruitment and accumulation of inflammatory cells in the perforated TMs was found to be similar between the plg deficient and the wt mice. Myringotomized TMs in uPA deficient mice healed similar to perforations of wt controls. Neither did the keratinocyte migration nor the occurrence of inflammatory cells differ between these genotypes. In the in vitro experiments TMs from plg deficient and wt mice, were dissected out, perforated and cultured in absence or surplus of plg. A decrease in perforation size was seen in all groups regardless of genotype or amount of plg in the medium. In conclusion, the present studies show: • Plg is essential for the healing of TM perforations in mice. • The altered healing process after a myringotomy in plg deficient mice involves a disturbed keratinocyte migration, a massive deposition of fibrin and an abundant accumulation of inflammatory cells in the wound area. • Plasminogen deficiency does not alter the early inflammatory response, following a myringotomy. • Deficiency of uPA does not influence the healing of TM perforations. • During in vitro conditions healing of TM perforations is initiated irrespectively of genotype of the explant (plg deficient or wt) or supply of plg. The increased knowledge of the involvement of plg in the healing of TM perforations may open therapeutical possibilities in the treatment of chronic TM perforations in humans.
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| 3. |
- Guo, Yongzhi, 1972-
(författare)
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Plasmin : a potent pro-inflammatory factor
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Plasmin, the central molecule of the plasminogen activator system, is a broad-spectrum serine protease. Plasmin is important for the degradation of fibrin and other components of the extracellular matrix (ECM) during a number of physiological and pathological processes. The aim of this thesis was to elucidate the functional roles of plasmin during pathological inflammation and infection in autoimmune and non-autoimmune diseases. For this purpose, mouse models of rheumatoid arthritis (RA), bacterial arthritis, infection, and sepsis have been used. Previous studies from our laboratory have shown that plasminogen-deficient mice are resistant to the development of collagen type II-induced arthritis (CIA). In contrast, others have shown that plasmin plays a protective role in antigen-induced arthritis (AIA). To investigate the contrasting roles of plasminogen deficiency in models of CIA and AIA, a new animal model of arthritis called local injection-induced arthritis (LIA) was developed. In this model, we replaced methylated bovine serum albumin, which is normally used as an immunogen in the AIA model, with collagen type II (CII) to induce arthritis. When wild-type and plasminogen-deficient mice were injected intra-articularly with CII or 0.9% NaCl following CIA induction, plasminogen-deficient mice developed typical CIA, but the disease was less severe than in wild-type mice and was restricted to the injected joints. When the AIA model was used, plasminogen-deficient mice developed a much more severe arthritis than the wild-type mice. These results indicate that both the antigen and joint trauma caused by the local injection are critical to explaining the contrasting roles of plasminogen deficiency in CIA and AIA. This indicates that CIA and AIA have distinct pathogenic mechanisms and plasmin plays contrasting roles in different types of arthritis models. To study the functional roles of plasmin in the host inflammatory response during infectious arthritis, a Staphylococcus aureus-induced bacterial arthritis model was established. When wild-type mice were injected intra-articularly with 1 × 106 colony-forming units (CFU) of S. aureus per joint, all the bacteria were completely eliminated from the injected joints in 28 days. However, in the plasminogen-deficient mice, the S. aureus counts were 27-fold higher at day 28 than at day 0. When human plasminogen was given to the plasminogen-deficient mice daily for 7 days, the bacterial clearance was greatly improved and the necrotic tissue in the joint cavity was also completely eliminated. Supplementation of plasminogen-deficient mice with plasminogen also restored the expression level of interleukin-6 (IL-6) in the arthritic joints. In summary, plasmin has protective roles during S. aureus-induced arthritis by enhancing cytokine expression, removing necrotic tissue, and mediating bacterial killing and inflammatory cell activation. The functional roles of plasmin during infection and sepsis were also studied in mice. Infection was induced by injecting 1 × 107 CFU of S. aureus intravenously and the sepsis model was induced by injecting 1.6 × 108 CFU of S. aureus. In the infection model, the wild-type mice had a 25-day survival rate of 86.7%, as compared to 50% in the plasminogen-deficient group. However, when sepsis was induced, the average survival for plasminogen-deficient mice was 3 days longer than for wild-type mice. Twenty-four hours after the induction of sepsis, the serum levels of IL-6 and IL-10 as well as the bacterial counts in all organs investigated were significantly higher in wild-type mice than in plasminogen-deficient mice. In wild-type mice, blockade of IL-6 by intravenous injection of anti-IL-6 antibodies significantly prolonged the onset of mortality and improved the survival rate during sepsis. These data indicate that plasmin plays different roles during infection and sepsis. Furthermore, plasmin appears to be involved in the regulation of inflammatory cytokine expression during sepsis. Taken together, our data indicate that plasmin plays multifunctional pro-inflammatory roles in different autoimmune and non-autoimmune diseases. The pro-inflammatory roles of plasmin include activation of inflammatory cells, regulation of cytokine expression, and enhancement of the bacterial killing ability of the host.
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| 4. |
- Wahlberg, Patrik, 1974-
(författare)
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Matrix degrading proteases in the ovary : expression and function
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Extracellular matrix degrading proteases from the plasminogen (plg) activator (PA) and the matrix metalloproteinase (MMP) systems have been implicated as important mediators of ovulation and corpus luteum (CL) formation and regression. The aim of this thesis was to investigate the expression and regulation of PAs and MMPs in the ovary and to examine their functional roles for CL formation and function. The expression of membrane-type MMP-1 (MT1-MMP) and its substrate gelatinase A (MMP-2) mRNAs was studied during pregnant mare serum gonadotropin (PMSG)/human chorionic gonadotropin (hCG)-induced ovulation in immature rats. These proteases were coordinately regulated so that both were highly expressed in the theca cells of large preovulatory follicles. This suggests that MT1-MMP activates gelatinase A in preovulatory follicles to degrade the follicular wall during ovulation. In pseudopregnant (psp) rats, MT1-MMP mRNA was expressed in the CL throughout the luteal phase. Tissue inhibitor of metalloproteases type-1 (TIMP-1) mRNA was expressed during CL formation and regression. MMP-2 and collagenase-3 mRNAs were expressed during CL formation and regression, respectively. When the luteal phase was artificially prolonged or shortened, TIMP-1 and collagenase-3 mRNAs were induced only after the serum progesterone levels had decreased, indicating a close association with luteolysis in the rat. In psp mice, the expression of mRNAs coding for both PAs, seven MMPs, and five protease inhibitors was studied. Most of the studied molecules were coordinately expressed during formation or regression of the CL. However, uPA, MT1-MMP, and TIMP-3 mRNAs were expressed throughout the luteal phase. The role of uPA was examined in psp uPA deficient mice. These mice displayed no abnormalities in luteal function or vascularity. The role of uPA is thus either not essential or can be compensated by other proteases in the absence of uPA. In order to control the timing of the CL formation, a mouse model for PMSG/hCG-induced CL formation was developed. Five different protocols were evaluated. One of them provided CL that were stable for six days. In that protocol the mice were treated with prolactin (PRL), twice daily from day 2 of CL life onward. The expression of the steroid acute regulatory protein (StAR) mRNA in the psp CL was also characterized to assess its use as a molecular marker for CL development and regression. It was highly expressed in the forming and functional CL and downregulated at a late stage of CL regression. The functional role of plg and MMPs for CL formation and function was investigated in plg deficient mice treated with the MMP inhibitor galardin (GM6001). Both psp mice and PMSG/hCG +PRL-induced CL formation were used. Several molecular markers for CL development and regression were used to evaluate the health status of the CL. Our data showed that healthy and vascularized CL formed even in plg deficient mice treated with the inhibitor. However, serum progesterone levels were significantly reduced in these mice, an effect that was mainly attributable to the plg deficiency. In conclusion, neither plg nor MMPs, alone or in combination, seem to be essential for the development of a functional CL.
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