Primary focal segmental glomerulosclerosis

1. E Nithin Paul1, Suchitha Satish1, Kiran Krishnamurthy Kelur2, Manjunath Sanjeev Shetty2
1 Department of Pathology, JSS Medical College, JSS Academy of Higher Education and
Research, Mysore, Karnataka, India
2 Department of Nephrology, JSS Medical College, JSS Academy of Higher Education and
Research, Mysore, Karnataka, India
AUTHORS

2. INTRODUCTION

3. Primary focal segmental glomerulosclerosis (FSGS) is a leading cause of nephrotic
syndrome in all age groups
IT has a high risk of progression to end stage renal disease (ESRD).
It is characterized histologically by the presence of mesangial sclerosis, obliteration of
glomerular capillaries with adhesions along with epithelial cell hypertrophy and
hyperplasia
Minimal change nephrotic syndrome (MCNS), a major cause of nephrotic syndrome in
adults and children
In contrast, it displays no abnormalities of the glomeruli when observed using light
microscopy.

4. The similar clinical presentation in MCNS and FSGS, the diagnosis of MCNS versus
primary FSGS relies exclusively on the histological findings in the biopsy
The distinction between the entities is usually made by the presence or absence of
sclerotic lesions in glomerular tuft
The distinction is difficult, particularly when biopsies are small and diagnostic segmental
lesions are not adequately sampled or when the glomerular injury is in an early pre-
sclerotic stage.
This differentiation has profound implications for treatment and prognosis

5. In the initial stages of glomerular injury, parietal epithelial cells (PECs) can become
activated and express CD44 de novo.
CD44 can be present within FSGS lesions and on Bowman's capsule, often in the
proximity of adhesion and plays a role in matrix deposition
CD44 is the main receptor for osteopontin and hyaluronic acid and is involved in cell
adhesion, matrix interaction, and migration.
Accordingly, CD44 is considered a marker of activated PECs that may distinguish
FSGS from minimal change disease.
By immuno-histological detection of CD44, even small FSGS lesions can be detected
which might otherwise be missed on histological sections

6. MATERIALS AND METHODS

7. The present study included 30 patients each of biopsy proven MCNS and FSGS.
 Patients with histological and immunofluorescent diagnoses of MCNS and primary
FSGS with a minimum of eight glomeruli for light microscopy and five for
immunofluorescence were included in the study.
Biopsies of primary FSGS with glomerulosclerosis and tubulo-interstitial damage (both
more than 25%) were excluded from the study.
Data was collected as per case-report forms. Variables of interest were measured at a
fixed point of time.

8. Table 1: Demographic, clinical, laboratory and histopathological parameters

9. For light microscopy, step serial sections from the renal core were stained and studied
using hematoxylin and eosin (H&E), periodic acid Schiff (PAS), Masson trichrome (MTS),
and Jones methenamine silver (JMS) stains.
 The histopathological parameters include the total number of glomeruli, number of
globally sclerotic glomeruli, number of segmentally sclerotic glomeruli, the presence of
podocyte hypercellularity, and mesangial hypercellularity were recorded.
The total percentage cortical area with tubular atrophy and interstitial fibrosis along with
arterial changes were documented.
For Immunofluorescence, 2-3-μ thin sections were cut and stained with fluorescein-
isothiocyanate conjugated [FITC] antibodies to immunoglobulins G, A, M, C3, C1q,
kappa, and lambda light chains and viewed under an immunofluorescent microscope -
Olympus BX 41.

10. The study protocol was approved by the Ethics Committee of JSS Medical College and
Hospital, JSS Academy of Higher Education and Research, India
(JSS/MC/PG/4623/2018-19).
The statistical analyses were performed using a statistical package for social sciences
IBM SPSS© version 23 (SPSS Inc, Chicago, IL, USA).
Continuous data were expressed as mean values ± standard deviation and categorical
variables as a percentage.
Comparisons between groups were performed with student's t-test for continuous data
and the Chi-square test (χ2) for categorical data.
Associated P values were reported for each of the baseline predictors. P < 0.05 was
considered statistically significant.

11. Immunohistochemistry (IHC) was performed on 3 μm thick sections on poly-l-lysine
coated slides.
 Sections were then incubated with anti-CD44 antibody (Mouse anti-human anti-CD44
Std./HCAM Monoclonal Antibody Ref: PM380AA (Clone: BC8), Biocare, Lot no: 052420)
for 30 minutes at room temperature followed by secondary antibody (MACH 1 Detection
kit, M1U539G Biocare) for 30 minutes.
 Sections from tonsil were taken as a positive control, whereas sections treated with the
tris-buffer solution instead of the primary antibody were used as a negative control.
In each biopsy, all glomeruli, except for those with global sclerosis, were evaluated
individually for the number of CD44-positive epithelial cells in an anatomical PEC
location.
CD44 staining in PECs or in VECs was scored positive when at least one cell showed
brown membrane positivity for CD44. Patients were classified into two groups according
to the presence or absence of CD44 staining.