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The clinical and molecular significance of different types of C4d staining in renal allografts

ABSTRACT: We investigated the clinical and molecular significance of minimal peritubular capillary (PTC) and isolated glomerular C4d+ staining using microarrays. Immunohistochemistry for C4d was performed on paraffin-embedded sections. Of the 255 biopsies analyzed, 51% were C4d negative, 4% were minimal, 15% focal or diffuse PTC C4d+, and 31% isolated glomerular C4d+. Minimal and focal/ diffuse PTC C4d+ staining were associated with a higher frequency of donor-specific anti-HLA antibodies (DSA) (67% vs. 82% vs. 25%), antibody mediated rejection (AMR) (66% vs. 89% vs. 19%) and mean glomerulitis (0.88 vs. 0.65 vs. 0.25, p=0.003), interstitial inflammation (1.25 vs. 1.41 vs. 0.79; p=0.003) and peritubular capillaritis scores (1.5 vs. 1.5 vs. 0.34; p < 0.001), compared to the C4d negative group, respectively. There were no differences in the DSA frequency, AMR rate, and Banff scores between isolated glomerular C4d+ and negative patients. While both minimal and focal/diffuse C4d+ biopsies showed increased expression of genes related to the immune response, and interferon-gamma and rejection induced, cytotoxic T cell and constitutive macrophage-associated pathogenesis based transcripts, there was no activation of immune-response related genes in isolated glomerular C4d+ biopsies. In summary, minimal PTC C4d+ staining but not isolated glomerular C4d+ staining is associated with AMR.

ORGANISM(S): Homo sapiens

PROVIDER: GSE38262 | GEO | 2012/05/29

SECONDARY ACCESSION(S): PRJNA167638

REPOSITORIES: GEO

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Project description:The presence of Donor-Specific anti-HLA Antibodies (DSA) is associated with an increased risk of both acute and chronic antibody-mediated rejection (AMR) in kidney allografts. AMR has remained challenging in kidney transplantation and is the major cause of late allograft loss. However, not all patients with DSA develop AMR, leading to the question of whether this represents accommodation, if other protective mechanisms exist or if this is actually a state of pre-rejection. Clinical and histological features, and gene expression profiles of kidney biopsy and blood samples of donor-specific antibody (DSA)+ patients without rejection were compared to antibody-mediated rejection (AMR) patients to elucidate the mechanisms involved in prevention of AMR. Of the 71 DSA+ patients, 46 had diagnosis of AMR and 25 did not show rejection. 50 DSA- patients without rejection were used as control. A subgroup of patients with available biopsy (n=61) and blood samples (n=54) were analyzed by microarrays. Both, DSA+/AMR+ and DSA+/AMR- biopsies showed increased expression of gene transcripts associated with cytotoxic T, natural killer cells, macrophages, interferon-gamma and rejection compared to DSA- biopsies. Regulatory T cell transcripts were up-regulated in DSA+/AMR+ and B cell transcripts in DSA+/AMR- biopsies. Whole blood gene expression analysis showed increased immune activity in only DSA+/AMR+ patients. There were no differentially expressed tolerant genes studied (n=14) in the blood or biopsy specimens of DSA+/AMR- patients. During a median 36 months follow-up, 4 DSA+/AMR- patients developed AMR, 12 continued to have DSAs but 9 lost DSAs. Gene expression profiles did not predict the development of AMR or persistence of DSAs. These results indicate increased immune activity in DSA+/AMR- biopsies despite lack of histologic findings of rejection. All clinically indicated kidney transplant biopsies performed at our institution after January 2009 were reviewed and 263 patients with anti-HLA antibody testing at the time of biopsy were identified. There were 71 DSA+ and 192 DSA- patients (Figure 1). Of the 71 DSA+ patients, 46 had biopsy diagnosis of acute AMR (n=9) or chronic AMR (n=37), and 25 had normal histopathology or minimal non-specific interstitial fibrosis/tubular atrophy (IFTA). Of the 192 DSA- patients, 50 patients with normal histology and/or mild non-specific IFTA were used as a control group. Clinical and histopathological findings of these 3 groups (DSA+/AMR+, DSA+/AMR- and DSA-) were analyzed. A subgroup of patients who were enrolled in the Institutional Review Board-approved âImmune Monitoring Studyâ who had clinically indicated biopsy (n=61) and whole blood samples (n=54) stored were used for genomic analysis. Twenty-eight biopsy and blood samples from DSA+/AMR+ patients, 13 biopsy and 14 blood samples from DSA+/AMR- patients, and 20 biopsy and 12 blood samples from DSA- patients, were available for microarray analysis.

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The clinical and molecular significance of different types of C4d staining in renal allografts

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