Molecular mechanisms of tissue injury induced by crystalline particles of different sizes and shapes

Honarpisheh, Mohammad Mohsen (2020): Molecular mechanisms of tissue injury induced by crystalline particles of different sizes and shapes. Dissertation, LMU München: Medizinische Fakultät

Abstract

Various crystals or crystalline particles are associated with clinical complications. The formation of crystalline particles within the wrong place of the body can result in cell injury and organ failure. For example, monosodium urate (MSU) deposition within joints cause gouty arthritis, deposition of CaOx in renal tubular compartment results in kidney injury, silica dust inhalation is associated with silicosis, and cholesterol promotes plaque and atherosclerosis progression. It is well-known that crystals can induce inflammation through activation of the NLR family, pyrin domain containing 3 (NLRP3), and inflammasome formation, which trigger interleukin 1 beta (IL-1β) and interleukin 18 (IL18) secretion. It has been shown that silica particles trigger apoptosis in macrophages. Although, our group showed that crystals cause necroptosis driven by receptor-interacting protein kinase 1 (RIPK1), receptor-interacting protein kinase 3 (RIPK3), and mixed lineage kinase domain-like pseudokinase (MLKL) proteins. In this study, four different metabolic crystals, including calcium oxalate (CaOx), MSU, calcium pyrophosphate dihydrate (CPPD), and cystine were used to show the cytotoxic effects on cells and organs. However, two main questions remained unclear; 1. Do environmental crystal particles induce necroptosis? And 2. Is another cell death pathway involved in crystal-induced cell death? To answer the first question, different crystal or crystalline particles such as silica, titanium dioxide (TiO2), cholesterol, and calcium phosphate (CaP) as environmental and MSU, CaOx, cholesterol, and CaP as metabolic crystalline particles were selected. Firstly, the expression level of regulated necrosis-related genes in different models was determined. We observed that Ripk3 and Mlkl were highly upregulated in acute and chronic oxalate nephropathy as well as acute and chronic ischemia-reperfusion injury as expected. Next, in a series of in-vitro and in-vivo experiments, the involvement of necroptosis was evaluated in response to environmental and metabolic crystalline particles. Pharmacological inhibition of Ripk1, Ripk3, and Mlkl prevented necroptosis cell death. In line with this finding using Mlkl-deficient primary renal tubular cells as well as siRNA against Ripk3 can reduce cell death and confirm the previous results. To check whether phagocytosis of crystals is required for inducing necroptotic cell death, we blocked phagocytosis using CytD. Interestingly, we saw that inhibiting phagocytosis significantly decreased cell death in response to crystals. However, targeting necroptosis did not result in a complete protection crystal-induced cell death. Therefore, we speculated that another cell death pathway involved. Previous studies showed a potential role for the MPT cell death pathway. Therefore, we hypothesized that the MPT pathway could play a role in crystal induce cytotoxicity. Indeed, the data confirm that MPT is involved in crystal particle-induced cell death. Taken together, our findings indicate that necroptosis and MPT-RN play an important role in crystal- or crystalline particle-induced cell death in-vitro as well as acute oxalate nephropathy in-vivo. These findings could be useful in developing new therapies for crystal- or crystalline particle-related diseases.

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Themengebiete: 600 Technik, Medizin, angewandte Wissenschaften ; 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin und Gesundheit
• Fakultäten: Medizinische Fakultät
• Sprache der Hochschulschrift: Englisch
• Datum der mündlichen Prüfung: 16. Oktober 2020
• 1. Bericht­erstatter:in: Anders, Hans-Joachim