REPORT FOR PATHOLOGICAL SOCIETY SMALL GRANT SCHEME
AWARD: GRANT REFERENCE NO. SGS 2011/010/08
Title: Role of Monocytes in the Pathogenesis of Transplant Glomerulitis
Name & Address: Ibrahim Batal, Department of Pathology
75 Francis Street, Brigham and Women's Hospital, Boston, MA 02115
Background: Transplant glomerulitis (TGI) is a relatively common allograft
lesion characterized by glomerular inflammation. TGI is capable of progressing
to chronic transplant glomerulopathy and allograft failure [1]. Although its
pathogenesis remains poorly understood, the association between the number
of intraglomerular monocytes and poor allograft survival suggests a pivotal
role of monocytes in the pathogenesis of TGI [2, 3].
Original Aims (copied from original application):
To utilize concurrent blood and tissue samples to characterize the role of
monocytes in TGI.
Results: (1) Biopsies were histologically scored according to the Banff 97
criteria for renal allograft pathology [4]. To facilitate comparison, samples
were classified into 3 groups: 1) TGI, 2) inflamed without TGI (inflamed
biopsies), and 3) no inflammation and no TGI (noninflamed biopsies).
(2) Peripheral blood was collected from renal transplant recipients at the day
of biopsy. Mononuclear cells were isolated and incubated without stimulation
for 48 hours. Cytokines were measured from the supernatant by using a 21plex cytokine Milliplex panel. In addition to the transplant cohort, blood was
collected from 9 healthy subjects serving as controls for cytokine secretion
under steady state.
Peripheral blood mononuclear cells (PBMCs) cultured from patients with TGI
produced significantly increased levels of IL-6 and IL-1β (which are largely
monocyte-derived cytokines) compared to healthy subjects and to patients
with noninflamed biopsies and a trend toward higher levels of IL-6 and IL-1β
compared to patients with inflamed biopsies (Table 1).
(3) The percentage of inflamed glomeruli showed significant correlation with
IL-6 and IL-1β levels (Table 2). Furthermore, the average number of
glomerular monocytes, but not lymphocytes, had significant association with
IL-6 and IL-1β levels (Table 2).
(4) Finally, using electron microscopy, TGI showed more severe signs of
acute and chronic endothelial injury when compared to inflamed and
noninflamed biopsies.
Conclusions: Glomerular inflammation correlates with endothelial injury,
monocyte influx, and IL-6 and IL-1β secretion by circulating immune cells.
How Closely Have the Original Aims been Met: We have met the aim
described in the original proposal with regard to the cytokines environment in
the peripheral blood. We showed that cytokines elevated in TGI samples are
largely monocytes derived (IL-6 and IL-1β), which correlated significantly with
the average number of intraglomerular monocytes.
Table 1: Cytokine levels (pg/ml) secreted by peripheral blood mononuclear
cells in kidney transplant patients and non-transplant healthy subjects
Healthy subjects Noninflamed
Inflamed
TGI
(n=9)
(n=21)
(n=21)
(n=17)
IL-6 1
27 (21, 48)
51 (19,125)
440 (86, 4813)
716 (226,
11684)
IL-1β 2
6 (3, 10)
8 (4, 21)
30 (8, 237)
77 (29, 960)
P values are for Kruskal Wallis tests comparing all groups; the detailed P values below are
the results of pair wise comparisons using Mann Whitney tests
1 IL-6: P<0.001 (TGI vs. noninflamed or healthy subjects), P < 0.003 inflamed vs.
noninflamed or healthy subjects), P=0.17 (TGI vs. inflamed)
2 IL-1β: P<0.001 (TGI vs. noninflamed and healthy subjects), P < 0.01 (inflamed vs.
noninflamed and healthy subjects), and P=0.13 (TGI vs. inflamed)
Table 2: Associations between log IL-6 and IL-1β levels secreted by peripheral
blood mononuclear cells in kidney transplant patients and glomerular
inflammation
Cytokines
Crude B
Crude p-value
Association with the percentage of inflamed glomeruli
0.003
Log IL-6
0.016
0.002
Log IL-1β
0.014
Association with the average number of intraglomerular CD68+ leukocytes
0.013
Log IL-6
0.123
0.003
Log IL-1β
0.129
Association with the average number of intraglomerular CD3+ leukocytes
Log IL-6
0.087
0.456
Log IL-1β
0.080
0.438
References;
1.
Batal, I., et al., A critical appraisal of methods to grade transplant
glomerulitis in renal allograft biopsies. Am J Transplant, 2010. 10(11): p.
2442-52.
2.
Tinckam, K.J., O. Djurdjev, and A.B. Magil, Glomerular monocytes predict
worse outcomes after acute renal allograft rejection independent of C4d
status. Kidney Int, 2005. 68(4): p. 1866-74.
3.
Papadimitriou, J.C., et al., Glomerular inflammation in renal allografts
biopsies after the first year: cell types and relationship with antibodymediated rejection and graft outcome. Transplantation, 2010. 90(12): p. 147885.
4.
Racusen, L.C., et al., The Banff 97 working classification of renal allograft
pathology. Kidney Int, 1999. 55(2): p. 713-23.
P
values
0.003
0.048