Donor-specific antibodies, glomerulitis, and human leukocyte antigen B eplet mismatch are risk factors for peritubular capillary C4d deposition in renal allografts / 中华医学杂志(英文版)

BACKGROUND@#The complement system plays an important role in the immune response to transplantation, and the diagnostic significance of peritubular capillary (PTC) C4d deposition (C4d+) in grafts is controversial. The study aimed to fully investigate the risk factors for PTC C4d+ and analyze its significance in biopsy pathology of kidney transplantation.@*METHODS@#This retrospective study included 124 cases of kidney transplant with graft biopsy and donor-specific antibody (DSA) testing from January 2017 to December 2019 in a single center. The effects of recipient pathological indicators, eplet mismatch (MM), and DSAs on PTC C4d+ were examined using univariate and multivariate logistic regression analyses.@*RESULTS@#In total, 35/124 (28%) were PTC C4d+, including 21 with antibody-mediated rejection (AMR), eight with renal tubular injury, three with T cell-mediated rejection, one with glomerular disease, and two others. Univariate analysis revealed that DSAs (P < 0.001), glomerulitis (P < 0.001), peritubular capillaritis (P < 0.001), and human leukocyte antigen (HLA) B eplet MM (P = 0.010) were the influencing factors of PTC C4d+. According to multivariate analysis, DSAs (odds ratio [OR]: 9.608, 95% confidence interval [CI]: 2.742-33.668, P < 0.001), glomerulitis (OR: 3.581, 95%CI: 1.246-10.289, P = 0.018), and HLA B eplet MM (OR: 1.166, 95%CI: 1.005-1.353, P = 0.042) were the independent risk factors for PTC C4d+. In receiver operating characteristic curve analysis, the area under the curve was increased to 0.831 for predicting PTC C4d+ when considering glomerulitis, DSAs, and HLA B eplet MM. The proportions of HLA I DSAs and PTC C4d+ in active antibody-mediated rejection were 12/17 and 15/17, respectively; the proportions of HLA class II DSAs and PTC C4d+ in chronic AMR were 8/12 and 7/12, respectively. Furthermore, the higher the PTC C4d+ score was, the more serious the urinary occult blood and proteinuria of recipients at the time of biopsy.@*CONCLUSIONS@#PTC C4d+ was mainly observed in AMR cases. DSAs, glomerulitis, and HLA B eplet MM are the independent risk factors for PTC C4d+.

Investigation of MHC gamma block C4A and C4B polymorphisms in unrelated hematopoietic stem cell transplantation

ABSTRACT Background: Immunological life-threatening complications frequently occur in post-hematopoietic stem cell transplantation (HSCT), despite matching recipient and donor (R/D) pairs for classical human leukocyte antigens (HLA). Studies have shown that R/D non-HLA disparities within the major histocompatibility complex (MHC) are associated with adverse effects post-HSCT. Methods: We investigated the impact of mismatches of single-nucleotide polymorphisms (SNPs) in C4A/C4B genes, for showing the highest diversity in the MHC gamma block, on 238 patients who underwent HLA 10/10 unrelated donor (URD) HSCT. The endpoints were acute graft-versus-host disease (aGVHD), chronic graft-versus-host disease (cGVHD) and mortality. One hundred and twenty-nine R/D pairs had 23 C4-SNPs typed by PCR-SSP (Gamma-Type™v.1.0), and 109 R/D pairs had these 23 SNPs identified by next-generation sequencing (NGS) using the Illumina platform. Results: The percentage of patients who received HSC from HLA 10/10 donors with 1-7 mismatches was 42.9%. The R/D pairs were considered C4 mismatched when bearing at least one disparity. These mismatches were not found to be risk factors for aGVHD, cGVHD or mortality after unrelated HSCT when SNPs were analyzed together (matched or mm ≥ 1), independently or according to the percentage of incompatibilities (full match for 23 SNPs; 1-3 mm and >3 mm). An exception was the association between 1-3 mismatches at the composite of SNPs C13193/T14952/T19588 with the development of aGVHD (P = 0.012) and with grades III-IV of this disease (P = 0.004). Conclusion: Our data are not consistent with the hypothesis that disparities in C4A/C4B SNPs increase the risks of post-HSCT adverse effects for the endpoints investigated in this study.

Impact of C4, C4A and C4B gene copy number variation in the susceptibility, phenotype and progression of systemic lupus erythematosus

Abstract Background Complement component 4 (C4) gene copy number (GCN) affects the susceptibility to systemic lupus erythematosus (SLE) in different populations, however the possible phenotype significance remains to be determined. This study aimed to associate C4A , C4B and total C4 GCN and SLE, focusing on the clinical phenotype and disease progression. Methods C4 , C4A and C4B GCN were determined by real-time PCR in 427 SLE patients and 301 healthy controls, which underwent a detailed clinical evaluation according to a pre-established protocol. Results The risk of developing SLE was 2.62 times higher in subjects with low total C4 GCN (< 4 copies, OR = 2.62, CI = 1.77 to 3.87, p < 0.001) and 3.59 times higher in subjects with low C4A GCN (< 2 copies; OR = 3.59, CI = 2.15 to 5.99, p < 0.001) compared to those subjects with normal or high GCN of total C4 (≥4) and C4A (≥2), respectively. An increased risk was also observed regarding low C4B GCN, albeit to a lesser degree (OR = 1.46, CI = 1.03 to 2.08, p = 0.03). Furthermore, subjects with low C4A GCN had higher permanent disease damage as assessed by the Systemic Lupus International Collaborating Clinics - Damage Index (SLICC-DI; median = 1.5, 95% CI = 1.2-1.9) than patients with normal or high copy number of C4A (median = 1.0, 95% CI = 0.8-1.1; p = 0.004). There was a negative association between low C4A GCN and serositis ( p = 0.02) as well as between low C4B GCN and arthritis ( p = 0.02). Conclusions This study confirms the association between low C4 GCN and SLE susceptibility, and originally demonstrates an association between low C4A GCN and disease severity.

Complement System and C4d expression in cases of Membranous nephropathy / Sistema complemento e expressão de C4d em casos de Glomerulopatia Membranosa

Abstract Introduction: Membranous nephropathy (MN) is one of the major causes of nephrotic syndrome. The complement system plays a key role in the pathophysiology of MN. Objectives: To identify the complement pathway possibly activated in MN cases and correlate the presence of C4d with more severe clinical and histological markers. Methods: Sixty nine cases from renal biopsy with membranous nephropathy were investigated. The presence of C1q was analyzed by direct immunofluorescence; and expression of C4d by immunohistochemistry. Clinical and epidemiological data were obtained upon biopsy request. Results: The presence of focal segmental glomerulosclerosis, global glomerulosclerosis, vascular lesions and tubulointerstitial fibrosis were collected by anatomopathological report. C4d(+) was found in 58 (84%), and C1q(+) was found in 12 (17%) of the cases. Twelve patients had C4d(+)/C1q(+), 46 had C4d(+)/C1q(-), and 11 patients had C4d(-)/C1q(-), probably indicating the activation of the classical, lectin and alternative pathways, respectively. Conclusion: C4d was associated with increased interstitial fibrosis, but not with clinical markers of poor prognosis. Through the deposition of C4d and C1q we demonstrated that all complement pathways may be involved in MN, highlighting the lectin pathway. The presence of C4d has been associated with severe tubulointerstitial lesions, but not with clinical markers, or can be taken as a universal marker of all cases of MN.

Resumo Introdução: A Glomerulopatia membranosa (GM) é uma das principais causas da síndrome nefrótica. O sistema do complemento desempenha um papel chave na fisiopatologia do GM. Objetivos: Identificar a via do complemento possivelmente ativada nos casos de GM e correlacionar a presença de C4d com marcadores clínicos e histológicos mais graves. Métodos: Foram investigados 69 casos de biópsia renal com GM. A presença de C1q foi analisada por imunofluorescência direta e a expressão de C4d por imunohistoquímica. Dados clínicos e epidemiológicos foram obtidos mediante solicitação de biópsia renal. Resultados: A presença de glomerulosclerose segmentar focal, glomeruloesclerose global, lesões vasculares e fibrose tubulointersticial foi coletada por relato anatomopatológico. C4d (+) foi encontrado em 58 (84%), e C1q (+) foi encontrado em 12 (17%) casos. Doze pacientes tinham C4d (+)/C1q (+), 46 tinham C4d (+)/C1q (-) e 11 pacientes tinham C4d (-)/C1q (-), indicando provavelmente a ativação da via clássica, da lectina e da alternativa, respectivamente. Conclusão: O C4d foi associado ao aumento da fibrose intersticial, mas não com marcador clínico de mau prognóstico. Através da deposição de C4d e C1q, demonstrou-se que todas as vias do complemento podem estar envolvidas em GM, destacando a via da lectina. A presença de C4d tem sido associada a lesões tubulointersticiais graves, mas não com marcadores clínicos, ou pode ser tomada como um marcador universal de todos os casos de GM.

Pathologic Updates on Antibody Mediated Rejection in Renal Transplantation / 대한이식학회지

Progress in the field of antibody mediated rejection (ABMR) in kidney transplantation has shown a rapid increase during the past two decades. New pathologic entities have emerged and replace old concepts and diagnostic terms. According to newly acknowledged facts discovered by clinicians, researchers, and pathologists all over the world, an updated classification, rather than Banff 07, is needed. In order to improve the diagnostic accuracy for ABMR in clinicians as well as pathologists, recognition and awareness of various conditions such as C4d-negative ABMR, subclinical ABMR, de novo donor specific antibody, microcirculation inflammation, isolated vascular lesion, antibody-mediated transplant arteriopathy, etc. are essentially important.

Significance of MICA antibody monitoring in management of acute and chronic rejection after renal transplantation / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the association of major histocompatibility complex class I chain related gene A (MICA) antibodies with acute rejection (AR), chronic rejection (CR) and renal function after renal transplantation.</p><p><b>METHODS</b>Serum MICA antibodies were detected with ELISA before and after transplantation with also examinations of panel reactive antibodies (PRA), serum creatinine, urine, graft ultrasound, lymphocyte subsets and the pathology of graft biopsy. The study was carried out in two parts to monitor MICA antibodies in acute and chronic rejections after renal transplantation.</p><p><b>RESULTS</b>In the first part of the study 18 of the 41 recipients experienced episodes of acute rejection, and the incidence rate was markedly higher in MICA(+) group than in MICA(-) group (P<0.05). Compared with the recipients with stable renal functions, the patients with acute graft rejection showed a significantly higher positivity rate of MICA antibodies. Postoperative MICA antibody monitoring showed that MICA antibody level increased gradually 2-3 days after the occurrence of acute rejection; anti-rejection treatment lowered serum creatinine to a normal level but MICA antibodies remained positive. In the second part, 21 of 40 patients had chronic graft rejection and showed significantly higher positivity rate of MICA than the patients with stable renal functions (P<0.05). In patients with chronic rejections, the serum creatinine levels were significantly higher in MICA(+) than in MICA(-) cases (P<0.05). Graft biopsy of all MICA(+) cases showed C4d deposition.</p><p><b>CONCLUSION</b>The status of MICA antibodies can predict the occurrence and treatment outcomes of acute rejection, and also as one of the major causes of chronic graft rejection, they affect the long-term survival of the renal grafts.</p>

Pesquisa de fração c4d e imunoglobulina para tratamento da rejeição aguda mediada por anticorpos no transplante renal / Search of c4d fraction and immunoglobulin for treatment of acute rejection mediated by antibodies in the Kidney transplantation

A rejeição aguda mediada por anticorpos, diagnosticada pela deposição de C4d na biópsia do enxerto, é uma complicação grave do transplante renal, com taxas históricas de perda do órgão transplantado da ordem de 30% -50%. Ainda que não existam ensaios clínicos adequadamente conduzidos para avaliar o papel da imunoglobulina no tratamento da RMA, a evidência proveniente de séries de casos publicadas por centros especializados aponta para uma taxa de preservação do enxerto em um ano de até cerca de 90% em com o uso da imunoglobulina humana intravenosa, sobretudo quando associada à plasmaférese, resultado esse muito superior ao controle histórico sem uso de imunoglobulina. Diante disso, recomenda-se a inclusão da imunoglobulina humana intravenosa no CEAF para o tratamento da rejeição aguda mediada por anticorpos comprovada por biópsia (presença de depósitos de C4d) pós-transplante renal, refratária a corticoide e OKT3. Não há evidências suficientes para recomendar um regime preferencial de administração de imunoglobulina em relação aos demais. Recomenda-se o regime mais estudado, constituído de imunoglobulina humana 500 mg/Kg/dia por até sete dias, quando utilizada isoladamente, ou 500 mg/Kg/dia em dias alternados, quando associada à plasmaférese. Recomendação da CONITEC: Os membros da CONITEC presentes na 7ª reunião ordinária do dia 02/08/2012 recomendaram a incorporação da pesquisa de fração C4d e da imunoglobulina para o tratamento da rejeição aguda mediada por anticorpos no transplante renal, conforme PCDT a ser elaborado pelo Ministério da Saúde. A Portaria SCTIE/MS Nº 36, de 27 de setembro de 2012 - Torna pública a decisão de incorporar a imunoglobulina para tratamento da rejeição aguda mediada por anticorpos no transplante renal e o exame de pesquisa da fração C4d no Sistema Único de Saúde.

Expression of MMP-2 and TIMP-1 in renal tissues of patients with chronic active antibody-mediated renal graft rejection / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the expressions of matrix metalloprotein-2 (MMP-2) and tissue inhibitor of metallopeptidase inhibitor-1 (TIMP-1) in the renal allografts of patients with chronic active antibody-mediated rejection (ABMR), and explore their role in the pathogenesis of ABMR.</p><p><b>METHODS</b>Immunohistochemistry and computer-assisted image analysis were used to detect the expression of MMP-2 and TIMP-1 in the renal allografts of 46 patients with interstitial fibrosis and tubular atrophy (IF/TA), with 15 normal renal tissue specimens as the control. The association of MMP-2 and TIMP-1 with the pathological grade of IF/TA in ABMR was analyzed.</p><p><b>RESULTS</b>The expressions of MMP-2 and TIMP-1 significantly increased in the renal tissues of the patients as compared with the normal renal tissues (P<0.05). MMP-2 expression tended to decrease, while TIMP-1 and serum creatinine increased with the pathological grades of IF/TA (P<0.05). In IF/TA group, the expression of TIMP-1 was positively correlated to serum creatinine level (r=0.718, P=0.00<0.05).</p><p><b>CONCLUSION</b>Abnormal expressions of MMP-2 and TIMP-1 can promote the development of renal fibrosis in chronic ABMR.</p>

Proteasome-Inhibitor-Based Primary Therapy for Antibody-Mediated Rejection in a Renal Transplant Recipient / 대한내과학회지

Donor-specific anti-human leukocyte antigen antibodies (DSA) following kidney transplantation predict the evolution of humoral rejection and reduced graft survival. Rapid, complete elimination of DSA during antibody-mediated rejection (AMR) is rarely achieved with traditional antihumoral therapies. We report the case of a 39-year-old female who was admitted for increasing azotemia and diagnosed with AMR based on diffusely positive histological changes on C4d immunostaining. In this case, bortezomib reversed the histological changes and induced a reduction in DSA. Proteasome-inhibitor-based combination therapy is a potential means for rapid DSA elimination in antibody-mediated rejection in renal transplant recipients.

Proteasome-Inhibitor-Based Primary Therapy for Antibody-Mediated Rejection in a Renal Transplant Recipient / 대한내과학회지

Donor-specific anti-human leukocyte antigen antibodies (DSA) following kidney transplantation predict the evolution of humoral rejection and reduced graft survival. Rapid, complete elimination of DSA during antibody-mediated rejection (AMR) is rarely achieved with traditional antihumoral therapies. We report the case of a 39-year-old female who was admitted for increasing azotemia and diagnosed with AMR based on diffusely positive histological changes on C4d immunostaining. In this case, bortezomib reversed the histological changes and induced a reduction in DSA. Proteasome-inhibitor-based combination therapy is a potential means for rapid DSA elimination in antibody-mediated rejection in renal transplant recipients.

Interactions of complement proteins C1q and factor H with lipid A and Escherichia coli: further evidence that factor H regulates the classical complement pathway

Proteins of the complement system are known to interact with many charged substances. We recently characterized binding of C1q and factor H to immobilized and liposomal anionic phospholipids. Factor H inhibited C1q binding to anionic phospholipids, suggesting a role for factor H in regulating activation of the complement classical pathway by anionic phospholipids. To extend this finding, we examined interactions of C1q and factor H with lipid A, a well-characterized activator of the classical pathway. We report that C1q and factor H both bind to immobilized lipid A, lipid A liposomes and intact Escherichia coli TG1. Factor H competes with C1q for binding to these targets. Furthermore, increasing the factor H: C1q molar ratio in serum diminished C4b fixation, indicating that factor H diminishes classical pathway activation. The recombinant forms of the Cterminal, globular heads of C1q A, B and C chains bound to lipid A and E. coli in a manner qualitatively similar to native C1q, confirming that C1q interacts with these targets via its globular head region. These observations reinforce our proposal that factor H has an additional complement regulatory role of down-regulating classical pathway activation in response to certain targets. This is distinct from its role as an alternative pathway down-regulator. We suggest that under physiological conditions, factor H may serve as a downregulator of bacterially-driven inflammatory responses, thereby fine-tuning and balancing the inflammatory response in infections with Gram-negative bacteria.

A Case of BK Virus Nephropathy with Strong C4d Deposition in a Renal Allograft Recipient / 대한신장학회지

C4d deposition in peritubular capillaries in renal allograft biopsies is a significant marker for diagnosis of antibody-mediated rejection. However, it is unclear whether C4d deposition could be derived from BK virus infection. We present a case of BK virus nephropathy with strong C4d deposition 10 months after kidney transplantation. The diagnosis of BK virus nephropathy was missed out, whereas strong C4d deposition was noted in the first biopsy and therefore anti-rejection therapy was started. The deterioration of renal function led to a evaluate the possibility of BK virus nephropathy with second graft biopsy and further studies of BK virus replication status. Second graft biopsy revealed BK virus nephropathy without rejection. Finally, discontinuation of immunosuppressants and addition of anti-viral therapy for BK virus resulted in recovery of renal function, despite development of pancytopenia and subsequent fungal infection after leflunomide therapy. As in this case, initial focal pathologic changes from BK virus nephropathy could be overlooked by light microscopy. In addition, even though C4d positivity in peritubular capillaries is a good marker for diagnosis of antibody-mediated rejection, the meticulous examinations of the localization of C4d is needed, considering BK virus activates complement pathways and therefore leads to deposition of C4d mainly in tubular basement membrane. Based on our case of BK virus nephropathy with strong C4d deposition, we suggest that C4d deposition could be derived from BK virus nephropathy and therefore, it should be differentiated from acute antibody- mediated rejection in a renal allograft recipient.

Intravenous Immunoglobulin Treatment in a Kidney Transplant Patient with Chronic Antibody-Mediated Rejection / 대한신장학회지

A 66-year-old male was admitted for increasing azotemia. He was diagnosed with chronic antibody- mediated rejection and had received a livingdonor renal transplant from his 32-year-old son prior to his admission. The peritubular capillaries of his kidney were diffusely positive on C4d immunostaining. It is known that there is an agreement between C4d staining and serological and histopathological data during rejection that is thought to have a humoral component. The role of alloantibodies in chronic renal allograft deterioration and the corresponding morphologic changes have been increasingly recognized during the recent years. However the treatment guidelines for chronic antibody-mediated rejection have not yet been established. Intravenous immunoglobulin (IVIG) has been shown to decrease the titers of anti-HLA antibodies in highly sensitized patients awaiting transplant. There are also numerous proposed mechanisms regarding how IVIG exerts its immunomodulatory action. As we have experienced chronic antibody-mediated rejection and how IVIG treatment improves renal function, we recognize that IVIG has the potential to be used for treating certain subgroups of chronic allograft nephropathy patients with positive C4d staining and anti-HLA antibodies.

Diagnosis of acute humoral rejection using immunofluorescence in renal allograft biopsies- one step towards better understanding!

Immunofluorescence (IF) studies are important diagnostic tool in understanding pathogenesis involved in graft injury. Acute humoral rejection (AHR) associated with circulating donor-specific cytotoxic antibodies, is a poor prognosticator for graft survival. It can be diagnosed by staining for C4d antibody using indirect IF technique. C4d staining required to diagnose AHR was made mandatory for reporting renal allograft biopsies in 7th Banff conference. We present 2 years experience of IF studies using C4d polyclonal antibody on 546 renal allograft biopsies belonging to two groups of patients; 464 from group A (tolerance induction protocol) and 82 from group B (controls). We observed C4d focal positivity in 4 (0.9%) biopsies from group A and 4 (4.9%) from group B. We conclude that it is advisable to collect simultaneous core biopsy samples for IF studies and light microscopy to give better definition of allograft injury and thereby support in clinical management.

Activation of Intrarenal Complement System in Mouse Model for Chronic Cyclosporine Nephrotoxicity

PURPOSE: Local activation of the complement system plays a role in target organ damage. The aim of our study was to investigate the influence of cyclosporine (CsA)- induced renal injury on the complement system in the kidney. MATERIALS AND METHODS: Mice fed a low salt (0.01%) diet were treated with vehicle (VH, olive oil, 1mL/kg/day) or CsA (30mg/kg/day) for one or four weeks. Induction of chronic CsA nephrotoxicity was evaluated with renal function and histomorphology. Activation of the complement system was assessed through analysis of the expression of C3, C4d, and membrane attack complex (MAC), and the regulatory proteins, CD46 and CD55. CsA treatment induced renal dysfunction and typical morphology (tubulointerstitial inflammation and fibrosis) at four weeks. RESULTS: CsA-induced renal injury was associated with increased the expression of C3, C4d, and MAC (C9 and upregulation of complement regulatory proteins (CD 46 and CD55). Immunohistochemistry revealed that the activated complement components were mainly confined to the injured tubulointerstitium. CONCLUSION: CsA-induced renal injury is associated with activation of the intrarenal complement system.

Significance of C4d deposition in the follicular lymphoma / 中华血液学杂志

<p><b>OBJECTIVE</b>To explore the significance of C4d deposition in follicular lymphoma (FL).</p><p><b>METHODS</b>The deposition of C4d was detected in samples from 133 cases of lymphoma by immunohistochemistry and FL was studied by the double stainings of CD35/C4d, CD21/C4d and Bcl-2/C4d,respectively.</p><p><b>RESULTS</b>Among the 26 FL tissues, irregular C4d deposition was seen in 19 tumor tissues. Double staining for CD35, CD21 or Bcl-2 showed the C4d deposition was around the follicular dendritic cells (FDC). There was no significant difference between the positive rate of C4d and the degree of lymphoma. No deposition was found in the diffuse areas of FL and other type lymphomas.</p><p><b>CONCLUSION</b>C4d deposition around the follicular dendritic cell in the neoplastic follicles is a specific indicator of follicular lymphoma.</p>

Peritubular Capillary C4d Deposition in Chronic Allograft Dysfunction

Peritubular capillary (PTC) C4d staining represents a marker for acute humoral rejection, however, the impact of positive staining on chronic allograft dysfunction has received little attention. Ninety-three renal allograft biopsies from 93 patients were selected from a total of 174 renal allograft biopsies, which were obtained 6 months or more after transplantation (median: 89 months). Fresh frozen renal tissue was stained with monoclonal antibody against C4d. Sixteen of 93 biopsies showed C4d staining in PTC. C4d staining was positive in 40% of acute rejection cases (n=15) and 21% of chronic rejection cases (n=24). When the samples were divided according to C4d positivity, the C4d (+) group had a higher proportion of acute rejection than the C4d (-) group. However, no significant difference was observed between the two groups in terms of the prevalence of chronic rejection. Degrees of histological injury including tubulitis, interstitial inflammation and interstitial fibrosis were not significantly different between C4d (+) and C4d (-) groups. However, the 2-year graft survival rate after biopsy was lower in the C4d (+) group than in the C4d (-) group (24.8% versus 59.0%, p=0.1255). C4d staining in PTC is associated with late acute rejection, but not with chronic rejection based on conventional morphologic criteria in patients with chronic allograft dysfunction.