Systemic lupus erythematosus (SLE) in Mice Histology/Histopathology Methods
Processing of Tissues
Kidneys are cut in half longitudinally and embedded in paraffin. If two kidneys are present from a single animal, one is cut longitudinally and one is cut in cross section, then both are embedded in a single block. Sections are cut and stained with H&E. An additional section may be stained for PAS.
Evaluation of Tissues
Kidneys were scored according to the following system, developed by Chan, Madaio, and Shlomchik [1] and modified by Bendele to suit the current lesion severity in this study. The percentage of glomeruli with crescents was also estimated, and protein casts were counted. Scores were determined based on these counts and measurements as follows:
Glomerulus Score and Measurement
The diameters of twenty representative glomeruli are measured for each kidney, and a mean is determined. A score is assigned based on that mean as follows:
- 0 = Normal, mean glomerular diameters is 65 µm or less
- 0.5 = Very minimal, mean glomerular diameter is 66 to 70 µm
- 1 = Focal or multifocal, minimal to mild, early proliferative, mean glomerular diameter is 71 to 80 µm
- 2 = Multifocal mild to moderate or mild diffuse proliferative, mean glomerular diameter is 81 to 90 µm
- 3 = Diffuse moderate proliferative with or without multifocal severe areas, mean glomerular diameter is 91 to 100 µm
- 4 = Marked diffuse proliferative, mean glomerular diameter is 101 to 110 µm
- 5 = Severe diffuse proliferative, mean glomerular diameter is >110 µm
Crescent Score and Percent
The percentage of glomeruli with crescents is estimated, and a score assigned as follows:
- 0 = No crescents
- 0.5 = Single glomerulus with crescent (1%)
- 1 = 2 to 4% of glomeruli have crescents
- 2 = 5 to 10% of glomeruli have crescents
- 3 = 11 to 25% of glomeruli have crescents
- 4 = 26 to 50% of glomeruli have crescents
- 5 = >50% of glomeruli have crescents
Protein Cast Severity (Cortical Tubules) Score
The number of tubules with protein casts is estimated (use comparable areas in both kidneys since one is cross and the other is longitudinal section), and a score assigned as follows:
- 0 = Normal tubules
- 0.5 = Very minimal: affects 1 to 2% of cortex
- 1 = Minimal: 3 to 10% of cortex
- 2 = Mild: Multifocal tubules with protein casts, affects 11 to 25% of cortex
- 3 = Moderate: Multifocal tubules with protein casts , affects 26 to 50% of cortex
- 4 = Marked: Multifocal tubules with protein casts, affects 51 to 75% of cortex
- 5 = Severe: Diffuse tubules with protein casts, affects greater than 75% of cortex
Interstitial Nephritis (Inflammation not obviously associated with vessels)
- 0 = Normal
- 0.5 = Very Minimal: Small focal area of MNC in pelvis only
- 1 = Minimal: Occasional small focal, accumulations of MNC. Affects less than 10% of total interstitium and generally localized around pelvis
- 2 = Mild: Multifocal small to larger infiltrates distributed around pelvis and cortex, affecting 10 to 25% of cortex area
- 3 = Moderate: Multifocal small to extensive infiltrates in pelvis and cortex, affecting 26 to 50% of cortex area
- 4 = Marked: Multifocal to diffuse infiltration, affects 51 to 75% of pelvis and cortex area
- 5 = Severe: Diffuse infiltration, affects 76 to 100% of pelvis and cortex area
Vasculitis
- 0 = Normal
- 0.5 = Very Minimal: One vessel with minimal perivascular infiltrate
- 1 = Minimal: Small but definite perivascular infiltrates (1 to 2)
- 2 = Mild: Multifocal (3 to 4) foci of perivascular infiltrate, no necrosis
- 3 = Moderate: Multifocal (5 to 6) foci of perivascular infiltrate, more extensive, may have some necrosis of vessel wall
- 4 = Marked: Multifocal (7 to 8) foci of perivascular infiltrate, extensive and may have some necrosis of vessel wall
- 5 = Severe: Multifocal (>8) foci of perivascular infiltrate, extensive with necrosis
Summed Score
A sum of the five histopathology scores is also calculated for each joint.
If PAS sections are evaluated, they are scored as follows, but not included in the summed score:
PAS score
- 0 = Normal glomerular Pas staining
- 0.5 = 1 to 5% of glomeruli have mild increase in staining with minimal if any increase in the rest
- 1 = 6 to 10% of glomeruli have moderate increase in PAS staining, the rest have minimal to mild increase
- 2 = 11 to 25% of glomeruli have marked increase in PAS staining, the rest have minimal to moderate increase
- 3 = 26 to 50% of glomeruli have marked to severe increase in PAS staining, the rest have minimal to moderate increase
- 4 = 51 to 75% of glomeruli have severe increase in PAS staining, the rest have mild to marked increase
- 5 = >75% of glomeruli have severe increase in PAS staining, the rest have mild to marked increase
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