Impaired Synthesis of Erythropoietin, Glutamine Synthetase and Metallothionein in the Skin of NOD/SCID/[gamma] c null and Foxn1 nu/nu Mice with Misbalanced Production of MHC Class II Complex

Issue Title: Special Issue in honor of Professor Armen Galoyan. Guest Editor: Abel Lajtha Most skin pathologies are characterized by unbalanced synthesis of major histocompatability complex II (MHC-II) proteins. Healthy skin keratinocytes simultaneously produce large amounts of MHC-II and regeneration-supporting proteins, e.g. erythropoietin (EPO), EPO receptor (EPOR), glutamine synthetase (GS) and metallothionein (MT). To investigate the level of regeneration-supporting proteins in the skin during misbalanced production of MHC-II, skin sections from nonobese diabetic/severe combined immunodeficient (NOD/SCID)/γ ^sub c^ ^sup null^ and or Foxn1 nu/nu mice which are a priory known to under- and over-express MHC II, respectively, were used. Double immunofluorescence analysis of NOD/SCID/γ ^sub c^ ^sup null^ skin sections showed striking decrease in expression of MHC-II, EPO, GS and MT. In Foxn1 nu/nu mouse skin, GS was strongly expressed in epidermis and in hair follicles (HF), which lacked EPO. In nude mouse skin EPO and MHC-II were over-expressed in dermal fibroblasts and they were completely absent from cortex, channel, medulla and keratinocytes surrounding the HF, suggest a role for EPO in health and pathology of hair follicle. The level of expression of EPO and GS in both mutant mice was confirmed by results of Western blot analyses. Strong immunoresponsiveness of EPOR in the hair channels of NOD/SCID/γ ^sub c^ ^sup null^ mouse skin suggests increased requirements of skin cells for EPO and possible benefits of exogenous EPO application during disorders of immune system accompanied by loss MHC-II in skin cells.[PUBLICATION ABSTRACT]