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Heart and Kidney Pathology in Different Combinations of FcγR-deficient Mice
60
ESVP/ECVP Proceedings 2012
148:1, 2013
Miscellaneous Oral Presentations ULTRASTRUCTURAL MITOCHONDRIAL ALTERATIONS IN EQUINE MYOPATHIES OF UNKNOWN ORIGIN K. Van Driessche, R. Ducatelle, K. Chiers, R. Van Coster and H. van der Kolk Department of Veterinary Pathology, Ghent University, Belgium Introduction: The purpose of this study was to examine mitochondrial ultrastructure in cases of equine myopathy. Aberrant mitochondrial structure was found in several patients of various breeds and age diagnosed with myopathy of unknown origin. Materials and Methods: Muscle biopsy samples were taken from patients diagnosed with myopathy of unknown aetiology and clinically healthy horses. A Bergstr€om needle was introduced in the vastus lateralis of the musculus quadriceps femoris. The muscle samples were taken from live animals or within 15 min of death. The samples were fixed in paraformaldehyde (1%) and glutaraldehyde (2.5%) in cacodylate buffer and embedded in epoxy resin medium for transmission electron microscopy. Vastus lateralis samples from all horses were also snap frozen and kept at -80 C. Results: Ultrastructural examination revealed various mitochondrial changes. In five patients the mitochondria had a remarkably different morphology in comparison with the control group, varying from long and slender mitochondria with an onion-shaped appearance on transverse section to extremely large mitochondria with excessively branched cristae. Conclusions: Very little is known about aberrant mitochondrial ultrastructure in veterinary medicine, especially in horses. This study has provided several case reports of mitochondrial ultrastructural changes in horses diagnosed with myopathy of unknown origin. Further biochemical studies will be performed on muscle biopsies from these patients.
ASSESSMENT OF COLONY FORMING CAPACITY OF THE CANINE HAIR FOLLICLE UNDER TWO DIFFERENT CULTURE CONDITIONS D.J. Wiener, M. Suter and M.M. Welle Institute for Animal Pathology, Vetsuisse-Faculty, University of Bern, Switzerland Introduction: Hair growth is dependent on the coordination of the phases of the hair cycle and a functional stem cell (SC) compartment. We assess the growth and differentiation potential of colonies derived from different anatomical locations of the hair follicle (HF) to define the location of follicular SCs in dogs. Materials and Methods: The colony forming capacity of the different HF locations (upper isthmus, lower isthmus, inferior portion) was assessed by microdissection of HFs. The proliferating or differentiating capacity of the colonies was assessed by immunofluorescence labelling for Ki67, a marker for cell proliferation, and for involucrin, a marker for differentiation. The experiments were conducted in two different media (cFAD, CELLnTEC 09) selected for their ability to promote SCs. Results: Colonies derived from the inferior portion exceeded the colonies derived from the isthmus parts in number and size. However, the colonies derived from the inferior portion were mainly involucrin positive, representing transient amplifying cells, while the colonies grown from isthmus cells consisted mainly of proliferating SCs. The CELLnTEC medium was superior to the cFAD medium in regard to the promotion of SC colonies. Conclusions: The colonies derived from the isthmus consisted mainly of proliferating SCs, while transient amplifying cells were derived from the inferior portion. To enhance growth of proliferating SCs, the medium from CELLnTEC was better adapted than cFAD medium.
HEART AND KIDNEY PATHOLOGY IN DIFFERENT COMBINATIONS OF FCgR-DEFICIENT MICE D. Salvatori *, W. Bergmann y, G. Grinwis y and S.J. Verbeek* *Leiden University Medical Center and yVeterinary Faculty, Utrecht, The Netherlands Introduction: The receptor family for the Fc part of immunoglobulin G (FcgR) consists of three activating receptors, FcgRI, FcgRIII and FcgRIV, counterbalanced by one inhibiting receptor, FcgRIIb. Mice deficient for FcgRIIb on mixed 129/C57BL/6 background are susceptible to the development of a lupus-like disease. Lupus arises as a consequence of the loss of immunological tolerance resulting in the production of antinuclear (auto) antibodies (ANA), which trigger chronic inflammation. Materials and Methods: To understand the contribution of the different activating FcgRs to the development of lupus we analyzed the phenotype of FcgRII-/- , FcgRII-/- RIII-/-, RII-/- FcgRIII-/- RI-/and FcgR-/- mouse lines. Results: All mice deficient for FcgRIIb developed a high incidence of high ANA titres with age. However, FcgRII-/- and FcgRIII-/RII-/- RI-/- mice developed proliferative lupus nephritis, systemic vasculitis, myocarditis, severe valvulopathies and severe lymphoid hyperplasia in secondary lymphoid organs, while the FcgRII-/- RIII-/line developed milder lesions without increased mortality. Conclusions: The hyperactive phenotype of FcgRIIB knock-out (KO) mice confirms its important role in the negative regulation of activating Fc receptors on effector cells. The severe phenotype of the triple KO suggests that the role of the activating FcgR is redundant and that the presence of a single activating FcgR, FcgRIV, is sufficient to drive immune complex-mediated chronic inflammation, resulting in increased mortality.
ESVP/ECVP Proceedings 2012
148:1, 2013
Miscellaneous Oral Presentations ULTRASTRUCTURAL MITOCHONDRIAL ALTERATIONS IN EQUINE MYOPATHIES OF UNKNOWN ORIGIN K. Van Driessche, R. Ducatelle, K. Chiers, R. Van Coster and H. van der Kolk Department of Veterinary Pathology, Ghent University, Belgium Introduction: The purpose of this study was to examine mitochondrial ultrastructure in cases of equine myopathy. Aberrant mitochondrial structure was found in several patients of various breeds and age diagnosed with myopathy of unknown origin. Materials and Methods: Muscle biopsy samples were taken from patients diagnosed with myopathy of unknown aetiology and clinically healthy horses. A Bergstr€om needle was introduced in the vastus lateralis of the musculus quadriceps femoris. The muscle samples were taken from live animals or within 15 min of death. The samples were fixed in paraformaldehyde (1%) and glutaraldehyde (2.5%) in cacodylate buffer and embedded in epoxy resin medium for transmission electron microscopy. Vastus lateralis samples from all horses were also snap frozen and kept at -80 C. Results: Ultrastructural examination revealed various mitochondrial changes. In five patients the mitochondria had a remarkably different morphology in comparison with the control group, varying from long and slender mitochondria with an onion-shaped appearance on transverse section to extremely large mitochondria with excessively branched cristae. Conclusions: Very little is known about aberrant mitochondrial ultrastructure in veterinary medicine, especially in horses. This study has provided several case reports of mitochondrial ultrastructural changes in horses diagnosed with myopathy of unknown origin. Further biochemical studies will be performed on muscle biopsies from these patients.
ASSESSMENT OF COLONY FORMING CAPACITY OF THE CANINE HAIR FOLLICLE UNDER TWO DIFFERENT CULTURE CONDITIONS D.J. Wiener, M. Suter and M.M. Welle Institute for Animal Pathology, Vetsuisse-Faculty, University of Bern, Switzerland Introduction: Hair growth is dependent on the coordination of the phases of the hair cycle and a functional stem cell (SC) compartment. We assess the growth and differentiation potential of colonies derived from different anatomical locations of the hair follicle (HF) to define the location of follicular SCs in dogs. Materials and Methods: The colony forming capacity of the different HF locations (upper isthmus, lower isthmus, inferior portion) was assessed by microdissection of HFs. The proliferating or differentiating capacity of the colonies was assessed by immunofluorescence labelling for Ki67, a marker for cell proliferation, and for involucrin, a marker for differentiation. The experiments were conducted in two different media (cFAD, CELLnTEC 09) selected for their ability to promote SCs. Results: Colonies derived from the inferior portion exceeded the colonies derived from the isthmus parts in number and size. However, the colonies derived from the inferior portion were mainly involucrin positive, representing transient amplifying cells, while the colonies grown from isthmus cells consisted mainly of proliferating SCs. The CELLnTEC medium was superior to the cFAD medium in regard to the promotion of SC colonies. Conclusions: The colonies derived from the isthmus consisted mainly of proliferating SCs, while transient amplifying cells were derived from the inferior portion. To enhance growth of proliferating SCs, the medium from CELLnTEC was better adapted than cFAD medium.
HEART AND KIDNEY PATHOLOGY IN DIFFERENT COMBINATIONS OF FCgR-DEFICIENT MICE D. Salvatori *, W. Bergmann y, G. Grinwis y and S.J. Verbeek* *Leiden University Medical Center and yVeterinary Faculty, Utrecht, The Netherlands Introduction: The receptor family for the Fc part of immunoglobulin G (FcgR) consists of three activating receptors, FcgRI, FcgRIII and FcgRIV, counterbalanced by one inhibiting receptor, FcgRIIb. Mice deficient for FcgRIIb on mixed 129/C57BL/6 background are susceptible to the development of a lupus-like disease. Lupus arises as a consequence of the loss of immunological tolerance resulting in the production of antinuclear (auto) antibodies (ANA), which trigger chronic inflammation. Materials and Methods: To understand the contribution of the different activating FcgRs to the development of lupus we analyzed the phenotype of FcgRII-/- , FcgRII-/- RIII-/-, RII-/- FcgRIII-/- RI-/and FcgR-/- mouse lines. Results: All mice deficient for FcgRIIb developed a high incidence of high ANA titres with age. However, FcgRII-/- and FcgRIII-/RII-/- RI-/- mice developed proliferative lupus nephritis, systemic vasculitis, myocarditis, severe valvulopathies and severe lymphoid hyperplasia in secondary lymphoid organs, while the FcgRII-/- RIII-/line developed milder lesions without increased mortality. Conclusions: The hyperactive phenotype of FcgRIIB knock-out (KO) mice confirms its important role in the negative regulation of activating Fc receptors on effector cells. The severe phenotype of the triple KO suggests that the role of the activating FcgR is redundant and that the presence of a single activating FcgR, FcgRIV, is sufficient to drive immune complex-mediated chronic inflammation, resulting in increased mortality.