Therapeutic opportunities of alpha-1-microglobulin A study in placenta, blood, skin and eye

Sammanfattning: This thesis describes functional studies of the human protein alpha-1-microglobulin (A1M), with the aim of exploring its usefulness as a therapeutic agent in diseases where oxidative stress is a prominent feature. A1M is a 26 kDa plasma and tissue protein with reductase activity and radical- and heme-binding antioxidative functions. The research focus in this thesis has been to study the in vivo protective mechanisms against oxidative stress in tissue of placenta, blood, skin and eye. Oxidative stress in the tissues were induced by disease, surgery, culturing or addition of pro-oxidants. Damage by oxidative stress in the tissues with or without addition of A1M was analyzed by biochemical methods and electron microscopy. The results show that A1M inhibits trophoblast barrier leakage, morphological damage and gene-upregulation related to oxidative stress in placenta tissue suffering from hemoglobin-induced oxidative stress, while simultaneously stimulating upregulation of genes related to extracellular matrix re-building. Skin explants, keratinocyte cultures, and purified collagen showed similar damage when exposed to heme and reactive oxygen species. Also in the skin, the damage was inhibited by A1M and signs of repair observed. In the vitreous of eyes from patients with rhegmatogenous retinal detachment, a significant correlation between oxidative stress, A1M-concentrations and disease severity parameters was shown. A newly described retina culture method, with improved biomechanical tissue support, displayed a reduced oxidative stress and optimal mitochondrial structure. Finally, A1M was shown to inhibit and repair oxidation of low density lipoprotein of blood by the neutrophil enzyme myeloperoxidase, an early event of atherosclerosis. The results suggest that the inhibition mechanism involves binding and degradation of the essential heme-group of myeloperoxidase by A1M. Taken together, the results suggest that A1M has a potential as a therapeutic agent in some diseases associated with pathological oxidative stress.