Renal glomerular fibrosis in two pigs

Additional Value of Second Harmonic Generation Microscopy in the Diagnosis of Feline Collagen Type III Glomerulopathy

A 1.5-year-old neutered female Domestic Shorthair cat was euthanized after the diagnosis of end-stage protein-losing nephropathy associated with the onset of nephrotic syndrome. At necropsy, both kidneys were diffusely pale and swollen with a granular cortex. Histologically, glomeruli had diffuse global mesangial and capillary wall expansion by homogeneous pale eosinophilic material. This material was Congo red negative, blue with Masson's trichrome stain, weakly positive with periodic acid-Schiff stain, bright red with Picrosirius red and birefringent under polarized light. Transmission electron microscopy and second harmonic generation (SHG) microscopy revealed mesangial and subendothelial collagen fibril deposition. Type III collagen deposition was confirmed by immunohistochemistry. This study provides an original and complete description of feline collagen type III glomerulopathy and emphasizes the possibility of directly diagnosing glomerular collagen deposition on unstained slides through SHG microscopy.

Diagnosis of Collagen Type III Glomerulopathy Using Picrosirius Red and PASH/Masson's Trichrome Stain

Canine collagen type III glomerulopathy (Col3GP) is a rare juvenile nephropathy in which irregular type III collagen fibrils and fibronectin accumulate in glomerular capillary walls and the mesangium. Necropsy findings were reviewed from 5 puppies diagnosed with Col3GP at 6 to 18 weeks of age. Histologically, with hematoxylin and eosin stain, the glomerular capillary walls and mesangium were diffusely and globally expanded by homogeneous pale eosinophilic material. Ultrastructurally, the subendothelial zone and mesangium were expanded by fibronectin and cross-banded collagen type III fibrils, diagnostic of Col3GP. Two additional stains were employed to identify the material within glomeruli as fibrillar collagen using light microscopy. In all 5 cases, the material was red with picrosirius red and birefringent under polarized light, and was blue with periodic acid-Schiff/hematoxylin/trichrome (PASH/TRI), thereby identifying it as fibrillar collagen. Based on these unique staining characteristics with picrosirius red and PASH/TRI, Col3GP may be reliably diagnosed with light microscopy alone.

Collagenofibrotic Glomerulonephropathy in a Cynomolgus Macaque (Macaca fascicularis)

Collagenofibrotic glomerulonephropathy (CFGN) is characterized by the deposition of type III collagen within the mesangial matrix and the absence of mesangial cell proliferation. A case of CFGN in a 2.7-year-old female cynomolgus macaque was investigated in the present study. Clinically, the animal was shown to have severe systemic edema along with hypoproteinemia. At necropsy, the kidneys were swollen and pale. The glomerular lesions were characterized by massive diffuse and global accumulation of fibrous materials in the mesangial areas. Neither mesangial cell proliferation nor changes in other organs were found. The fibrous materials were confirmed by the results of immunohistochemical and electron microscopic findings to consist mainly of randomly arranged, curve-shaped, twisted, and entwined type III collagen. This is the first case report of CFGN in nonhuman primates to date.

Glomerular Collagen V Codeposition and Hepatic Perisinusoidal Collagen III Accumulation in Canine Collagen Type III Glomerulopathy

Collagen type III glomerulopathy, also known as collagenofibrotic glomerulopathy, is a rare renal disease of unknown pathogenesis. The disease occurs in humans and animals and is characterized by massive glomerular accumulations of collagen type III. In the present study, we describe a Drever dog litter affected by an early onset variant of this glomerular disease, where 4 of 9 puppies developed renal failure within 50 days of age. Necropsy specimens of kidney from the 4 affected cases were studied by light microscopy, electron microscopy, and immunohistochemistry, and characteristic lesions compatible with a diagnosis of collagen type III glomerulopathy were found. In addition, 2 cases showed atypical epithelium in the collecting ducts of the medulla, so-called adenomatoid change. Immunohistochemistry of renal specimens from collagen type III glomerulopathy-affected dogs ( n = 10) originating from two different dog strains, the Drever dogs and a mixed-breed strain, demonstrated that the deposited glomerular collagen is composed of a mixture of collagen III and collagen V. The distribution of the collagen V corresponded to the localization of collagen III; however, differences in staining intensity showed that collagen type III is the dominating component. Immunohistochemistry for collagen III ( n = 9) and a transmission electron microscopic study ( n = 1) showed hepatic perisinusoidal collagen type III deposition in affected cases from both dog strains. This is the first report documenting glomerular accumulations of collagen type V and perisinusoidal liver collagen III deposition in canine collagen type III glomerulopathy.

A clinical study of canine collagen type III glomerulopathy

BACKGROUND

Collagen type III glomerulopathy (Col3GP), also known as collagenofibrotic glomerulonephropathy, is a rare renal disease with unknown pathogenesis that occurs in animals and humans. We recently described a naturally occurring canine autosomal recessive model of Col3GP, and the aim of the present work was to study the clinical features of canine Col3GP and compare with the human phenotype. In humans two different clinical syndromes with different age at onset (child- or adulthood) have been observed. In children a more aggressive course with familial occurrence is described, characterized by progressively increasing proteinuria, nephrotic syndrome, hypertension and chronic renal failure. A markedly increased serum level of the aminoterminal propeptide of type III procollagen (PIIINP) is considered a useful marker for the disease. Since Col3GP and concurrent hypocomplementemia have been observed in humans, we also aimed to investigate if hypocomplementemia was present in Col3GP affected dogs. A litter consisting of seven puppies, four Col3GP affected and three healthy unaffected, was observed from the day of birth until the affected puppies developed a mild or moderate renal azotemia.

RESULTS

During the period of observation growth retardation, increasing blood pressure, progressive proteinuria, azotemia, hypoalbuminemia, hypercholesterolemia and increased serum PIIINP were observed in all the affected dogs. Hypocomplementemia was not detected. Affected dogs were euthanized between 109 and 144 days of age, and pathological examinations revealed ascites and massive glomerular accumulations of collagen type III, consistent with Col3GP.

CONCLUSIONS

Dogs with Col3GP develop juvenile chronic renal failure, preceded by nephrotic syndrome, elevated serum PIIINP and hypertension, thus have similar clinical features as the juvenile Col3GP in humans. Further studies of this naturally occurring canine phenotype may provide more information on the pathogenesis and genetics of Col3GP in both animals and humans.

A canine autosomal recessive model of collagen type III glomerulopathy

Collagen type III glomerulopathy (Col3GP) is a rare renal disease characterized by massive glomerular accumulations of collagen type III. The disease occurs in both humans and animals, and has been presumed to be heritable with an autosomal recessive inheritance pattern. The pathogenesis is unknown. We describe herein a condition of canine autosomal recessive Col3GP. This spontaneously occurring canine disease was incidentally diagnosed in six mongrel dogs. We then established and studied a pedigree segregating the disease to confirm the genetic nature and inheritance of canine Col3GP. Twenty-nine percent of offspring (14/48) were affected, strongly supporting a simple autosomal recessive inheritance pattern. Kidney specimens were studied by light microscopy, electron microscopy (EM), immunohistochemistry and in situ hybridization. Characteristic findings of Col3GP previously reported in both humans and animals were demonstrated, including massive glomerular collagen type III deposition, and evidence of local mesangial collagen type III synthesis was found. We propose that canine Col3GP may serve as an animal model of human Col3GP. Our initial studies, using simple segregation analysis, showed that the Col3A1 gene was not involved in the disease. This is the first animal model of Col3GP, and further studies of this phenotype in dogs may have the potential to provide information on the pathogenesis and genetics of the disease in both animals and humans, and may thus contribute to the development of treatment regimes.

Collagenofibrotic Glomerulonephropathy with Fibronectin Deposition in a Dog

We report herein a case of collagenofibrotic glomerulonephropathy in a 3-year-old Shiba Inu with severe proteinuria. Histologically, renal glomeruli were enlarged with massive deposition of a homogeneous eosinophilic substance within the mesangium and capillary walls. The deposits reacted weakly with periodic acid-Schiff, stained deep blue with Masson's trichrome, and were positive by immunofluorescence for type III collagen and fibronectin. Ultrastructurally, the deposits consisted of fibrils and amorphous material in the mesangial matrix and beneath the glomerular capillary endothelium. The fibrils had transverse bands analogous to those of collagen fibrils. Electron microscopy also revealed focal detachment of podocytes and foot process effacement in glomerular tufts, which suggested that podocyte injury had contributed to the development of proteinuria in this dog. The current case resembles collagenofibrotic glomerulonephropathy (CFGN) in humans in histopathologic, immunofluorescence, and electron microscopic findings. This is the first report of CFGN in a nonhuman species with glomerular deposition of fibronectin and type III collagen.

Renal glomerular fibrosis in a cat

Renal glomerular fibrosis was observed in a 1-year-old spayed female Japanese domestic cat that showed clinically advanced renal failure. In the glomeruli, increased homogeneous materials were stained strongly with aniline blue by Masson's trichrome and positive for anti-type III collagen antibody by immunohistochemical staining, causing mesangial sclerosis and capillary collapse. By electron microscopy, randomly arranged fibrils were observed in the expanded subendothelial and mesangial areas, and the fibrils showed periodicity characteristic of collagen fibers in longitudinal sections. These findings of glomerular lesions closely resemble those of human "collagenofibrotic glomerulonephropathy," which has recently been described as a new type of glomerulonephropathy.