THSD7A-positive membranous nephropathy after kidney transplantation: A case report

Membranous nephropathy (MN) is a common cause of nephrotic syndrome after kidney transplantation (KT); however, scarce is known regarding post-KT thrombospondin type-1 domain-containing 7A (THSD7A)-positive MN. Herein, we report on a 72-year-old woman with end-stage kidney disease due to chronic interstitial nephritis (1996). In February 2020, she received a second deceased-donor KT, achieving optimal kidney function but presenting early post-KT proteinuria, reaching up to 1800mg/24h six months after transplantation, controlled with renin-angiotensin-aldosterone system (RAAS) blockade. In July 2021, a kidney allograft biopsy revealed features consistent with MN. Immunohistochemical stains showed diffuse and granular THSD7A and C4d deposition in glomerular capillary walls and negative PLA2R and IgG4 staining. No anti-THSD7A antibodies were detected in the serum. The pre-implantation biopsy showed no MN-associated lesions and negative THSD7A staining. Secondary triggers such as malignancy were discarded. The present report illustrates a THSD7A-positive MN in a KT recipient. Despite lacking native kidney biopsy and early presentation, a recurrent MN seemed unprovable due to documented native kidney disease and a long time span between native kidney disease and MN diagnosis. We, therefore, presumed primary de novo disease. Two years after KT, kidney function remains stable, and the patient has reached complete remission of proteinuria.

Evolution of kidney allograft loss causes over 40 years (1979-2019)

INTRODUCTION

The improvement of kidney allograft recipient and graft survival showed a decrease over the last 40 years. Long-term graft loss rate remained stable during a 25-year time span. Knowing the changing causes and the risk factors associated with graft loss requires special attention. The present study aimed to assess the causes of graft loss and kidney allograft recipient death. Also, we aimed to compare two different periods (1979-1999 and 2000-2019) to identify changes in the characteristics of the failed allografts and recipient and donors profile.

METHODS AND PATIENTS

We performed a single-center cohort study. We included all the kidney transplant recipients at the Hospital del Mar (Barcelona) between May 1979 and December 2019. Graft loss was defined as recipient death with functioning graft and as loss of graft function (return to dialysis or retransplantation). We assessed the causes of graft loss using clinical and histological information. We also analyzed the results of the two different transplant periods (1979-1999 and 2000-2019).

RESULTS

Between 1979 and 2019, 1522 transplants were performed. The median follow-up time was 56 (IQR 8-123) months. During follow-up, 722 (47.5%) grafts were lost: 483 (66.9%) due to graft failure and 239 (33.1%) due to death with functioning graft. The main causes of death were cardiovascular (25.1%), neoplasms (25.1%), and infectious diseases (21.8%). These causes were stable between the two periods of time. Only the unknown cause of death has decreased in the last period. The main cause of graft failure (loss of graft function) was the allograft chronic dysfunction (75%). When histologic information was available, antibody-mediated rejection (ABMR) and interstitial fibrosis/tubular atrophy (IF/TA) were the most frequent specific causes (15.9% and 12.6%). Of the graft failures, 213 (29.5%) were early (<1 year of transplantation). Vascular thrombosis was the main cause of early graft failure in the second period (2000-2019) (46.7%) and T-cell-mediated rejection (TCMR) was the main cause (31.3%) in the first period (1979-1999). The causes of late graft loss were similar between the two periods.

CONCLUSIONS

The causes of kidney allograft recipient death are still due to cardiovascular and malignant diseases. Vascular thrombosis has emerged as a frequent cause of early graft loss in the most recent years. The evaluation of the causes of graft loss is necessary to improve kidney transplantation outcomes.

Microvascular inflammation in the absence of human leukocyte antigen-donor-specific antibody and C4d: An orphan category in Banff classification with cytotoxic T and natural killer cell infiltration

Isolated microvascular inflammation (iMVI) without HLA donor-specific antibodies or C4d deposition in peritubular capillaries remains an enigmatic phenotype that cannot be categorized as antibody-mediated rejection (ABMR) in recent Banff classifications. We included 221 kidney transplant recipients with biopsies with ABMR (n = 73), iMVI (n = 32), and normal (n = 116) diagnoses. We compared peripheral blood leukocyte distribution by flow cytometry and inflammatory infiltrates in kidney transplant biopsies among groups. Flow cytometry showed fewer lymphocytes and total, CD4+, and CD8+ peripheral T cells in iMVI compared with ABMR and normal cases. ABMR and iMVI had fewer total natural Killer (NK) cells but more NKG2A+ NK cells. Immunohistochemistry indicated that ABMR and iMVI had greater CD3+ and CD68+ glomerular infiltration than normal biopsies, whereas CD8+ and TIA1+ cells showed only increased iMVI, suggesting they are cytotoxic T cells. Peritubular capillaries displayed more CD3+, CD56+, TIA1+, and CD68+ cells in both ABMR and iMVI. In contrast, iMVI had less plasma cell infiltration in peritubular capillaries and interstitial aggregates than ABMR. iMVI displayed decreased circulating T and NK cells mirrored by T cell and NK cell infiltration in the renal allograft, similar to ABMR. However, the lesser plasma cell infiltration in iMVI may suggest an antibody-independent underlying stimulus.

Phosphorylation of S6RP in peritubular capillaries of kidney grafts and circulating HLA donor-specific antibodies

Antibody-mediated rejection (ABMR) caused by donor-specific HLA-antibodies (DSA) is a mediator of allograft loss after kidney transplantation (KT). DSA can activate microvascular endothelium damage through the mTOR pathway. In this study we assessed the mTOR pathway activation by DSA in KT with ABMR (ABMR + DSA+) compared to controls (ABMR−DSA−), biopsies with ABMR changes without DSA (ABMR + DSA−) and DSA without ABMR changes (ABMR−DSA+), and the potential modulation by mTOR inhibitors (mTORi). We evaluated 97 biopsies: 31 ABMR + DSA+, 33 controls ABMR-DSA−, 16 ABMR + DSA−, and 17 ABMR-DSA+ cases. Regarding immunosuppression of full ABMR + DSA+ and controls, 21 biopsies were performed under mTORi treatment (11 of them ABMR + DSA+ cases) and 43 without mTORi (20 of them ABMR + DSA+) so as to explore its effect on the mTOR pathway. Biopsies were stained for C4d, Ki67, and phosphorylated (p) S6RP, ERK, and mTOR by immunohistochemistry. Labeling was graded according to peritubular capillary staining. ABMR biopsies showed significantly higher C4d, p-S6RP, and Ki67 staining in peritubular capillaries (PTC) compared to controls, and light differences in p-ERK or p-mTOR. mTORi treatment did not modify p-S6RP, p-mTOR, and p-ERK staining. Diffuse p-S6RP in PTC in the biopsies significantly associated with circulating HLA-DSA independently of graft rejection, and with worse death-censored graft survival. These findings suggest that activation of endothelium through the mTOR pathway evidence different mechanisms of damage in ABMR + DSA+ and ABMR + DSA− despite similar histological injury.

Influence of sex on cardiovascular outcomes in RBM20 variant carriers

Background

Variants in the RBM20 gene cause dilated cardiomyopathy and may be associated with a poor prognosis.

Objectives

To determine disease penetrance, the risk of adverse events and the influence of sex on outcomes in RBM20 variant carriers.

Methods

Consecutive probands and relatives carrying pathogenic or likely pathogenic RBM20 variants were retrospectively recruited from 12 cardiomyopathy units. The primary endpoint was a composite of malignant ventricular arrhythmia (MVA) and end-stage heart failure (ESHF). MVA and ESHF endpoints were also analysed separately and males and females compared.

Results

Longitudinal follow-up data were available for 163 RBM20 variant carriers (82 male, median age 36.5 years, median follow-up 77.6 months). 10/163 had an MVA event at baseline. 30/153 without baseline MVA (19.6%) reached the primary endpoint with a trend towards worse outcomes in males (p=0.08). 16/153 (10.5%) had new MVA with no difference between males and females (p=0.92). 20/163 (12.2%) developed ESHF (17 males and 3 females; p&lt;0.001).

By the end of follow-up, 114 patients (70%) had either left ventricular systolic dysfunction (LVSD) or had experienced MVA. 22 patients received a first diagnosis of LVSD during follow-up. Disease penetrance in individuals over 40 years of age was 78.5% by last evaluation.

Eleven patients that reached the MVA endpoint had a left ventricular ejection fraction (LVEF) available within 6 months of the event. Median [IQR] contemporary LVEF was 30% [23.75, 40%]. 5/11 patients had a contemporary LVEF &gt;35%. 1/11 had a contemporary LVEF &gt;45% (a female, 1st degree relative presenting with sustained ventricular tachycardia and an LVEF of 65%).

Conclusions

RBM20 variants are highly penetrant. The risk of MVA in male and female RBM20 variant carriers is similar but male sex is strongly associated with ESHF. MVA events occur in patients with LVEF &gt;35%.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): British Heart Foundation Clinical Research Training Fellowship

FC 109: Microvascular Inflammation in Kidney Transplant Biopsies in the Absence of HLA-DSA Displays Intense Cytotoxic T-Cell and NK Cell but not Plasma Cell Infiltration

BACKGROUND AND AIMS

Microvascular inflammation (MVI) without evidence of HLA-donor-specific antibodies (HLA-DSA) or C4d+ deposition remains an enigmatic phenotype, which cannot be classified as antibody-mediated rejection (ABMR) according to recent Banff classifications. We aimed to compare peripheral blood lymphocyte (PBL) distribution and infiltrating immune cells in kidney transplant (KT) biopsies presenting MVI (g + ptc ≥ 2) without C4d+ and HLA-DSA, ABMR and normal histology to explore the role of immune cells in these entities.

METHODS

A total of 221 allograft biopsies with ABMR (n = 73), MVI (n = 32) and normal (n = 116) diagnoses were analysed.

RESULTS

MVI patients showed a decrease in the absolute number of T-cells compared with ABMR and normal cases (P = 0.020 and P = 0.006) due to a significant decrease of CD4+ T-cells compared to normal cases (P = 0.013) and a reduction of CD8+ T-cells compared with ABMR (P = 0.029). ABMR and MVI presented a lower absolute number of circulating Natural Killer (NK) cells than normal cases. Immunohistochemistry assessment was performed in 22 ABMR, 13 MVI and 16 normal cases. Glomeruli in ABMR and MVI had more T-cells and CD68+ infiltration than normal biopsies, although TIA1+ was only increased in MVI (P &lt; 0.001), suggesting increased T-cell cytotoxic capacity. Peritubular capillaries displayed more circulating T-cells, CD56+ TIA1+ and CD68+ in ABMR and MVI groups. Contrarily, MVI cases showed mild circulating plasma cell infiltration (CD138+) in peritubular capillaries (P = 0.059) and interstitial aggregates (P = 0.024) compared with ABMR (Figure 1).

CONCLUSION

In conclusion, MVI without HLA-DSA and C4d+ displays decreased circulating T-cell and NK cells, and intense T-cell and NK cell cytotoxic infiltration in the allograft, similar to ABMR. However, the deficiency of plasma cell infiltration in MVI suggests a different underlying stimulus from ABMR.

Podocytopathy in patients with monoclonal gammopathy: three patients and literature review

BACKGROUND

Renal manifestations of monoclonal gammopathies are of increasing interest among nephrologists. Typical manifestations include light chain cast nephropathy, amyloidosis or renal damage mediated by monoclonal immunoglobulin deposition. Podocytopathies in the setting of an underlying monoclonal gammopathy constitute a rare manifestation of these diseases and, although being described in the literature, remain a challenge since most data derive from case reports.

METHODS

A retrospective review of the clinical data of Hospital del Mar and Hospital Vall d'Hebron was performed to identify patients with minimal change disease (MCD) or focal and segmental glomerulosclerosis (FSGS) in the setting of neoplasms that produce monoclonal (M) protein. Additionally, a literature review on this topic was performed. This study aims to describe the clinical characteristics and outcomes of these patients.

RESULTS

Three patients were identified to have podocytopathy and monoclonal gammopathy between the years 2013 and 2020. All three were males and  >65 years of age. Two patients were diagnosed with MCD and one patient was diagnosed with FSGS. All patients underwent a kidney biopsy and light and electron microscopic studies were performed. The underlying causes of monoclonal gammopathy were multiple myeloma in two cases and Waldeström macroglobulinemia in one case. Two patients developed nephrotic syndrome during the follow-up. All patients were under active hematological treatment. One patient presented a complete remission of proteinuria whereas the other two presented a partial remission.

CONCLUSIONS

Podocytopathies may infrequently be found in patients with monoclonal gammopathies. Patients with overt glomerular proteinuria and hematological disorders with M protein should undergo a kidney biopsy for prompt diagnosis and to specify a prognosis. In addition, further study on this matter must be done to understand the pathophysiology and treat these patients appropriately.

Redefining the Role of ADAM17 in Renal Proximal Tubular Cells and Its Implications in an Obese Mouse Model of Pre-Diabetes

Acute and chronic kidney lesions induce an increase in A Disintegrin And Metalloproteinase domain 17 (ADAM17) that cleaves several transmembrane proteins related to inflammatory and fibrotic pathways. Our group has demonstrated that renal ADAM17 is upregulated in diabetic mice and its inhibition decreases renal inflammation and fibrosis. The purpose of the present study was to analyze how Adam17 deletion in proximal tubules affects different renal structures in an obese mice model. Tubular Adam17 knockout male mice and their controls were fed a high-fat diet (HFD) for 22 weeks. Glucose tolerance, urinary albumin-to-creatinine ratio, renal histology, and pro-inflammatory and pro-fibrotic markers were evaluated. Results showed that wild-type mice fed an HFD became obese with glucose intolerance and renal histological alterations mimicking a pre-diabetic condition; consequently, greater glomerular size and mesangial expansion were observed. Adam17 tubular deletion improved glucose tolerance and protected animals against glomerular injury and prevented podocyte loss in HFD mice. In addition, HFD mice showed more glomerular macrophages and collagen accumulation, which was prevented by Adam17 deletion. Galectin-3 expression increased in the proximal tubules and glomeruli of HFD mice and ameliorated with Adam17 deletion. In conclusion, Adam17 in proximal tubules influences glucose tolerance and participates in the kidney injury in an obese pre-diabetic murine model. The role of ADAM17 in the tubule impacts on glomerular inflammation and fibrosis.

Non-HLA Antibodies and Epitope Mismatches in Kidney Transplant Recipients With Histological Antibody-Mediated Rejection

Background

Correlation between antibody-mediated rejection (ABMR) and circulating HLA donor-specific antibodies (HLA-DSA) is strong but imperfect in kidney transplant (KT) recipients, raising the possibility of undetected HLA-DSA or non-HLA antibodies contributing to ABMR. Detailed evaluation of the degree of HLA matching together with the identification of non-HLA antibodies in KT may help to decipher the antibody involved.

Methods

We retrospectively assessed patients with transplant biopsies scored following Banff'15 classification. Pre- and post-transplant serum samples were checked for HLA and non-HLA antibodies [MICA-Ab, angiotensin-II type-1-receptor (AT1R)-Ab, endothelin-1 type-A-receptor (ETAR)-Ab and crossmatches with primary aortic endothelial cells (EC-XM)]. We also analyzed HLA epitope mismatches (HLA-EM) between donors and recipients to explore their role in ABMR histology (ABMRh) with and without HLA-DSA.

Results

One-hundred eighteen patients with normal histology (n = 19), ABMRh (n = 52) or IFTA (n = 47) were studied. ABMRh patients were HLA-DSApos (n = 38, 73%) or HLA-DSAneg (n = 14, 27%). Pre-transplant HLA-DSA and AT1R-Ab were more frequent in ABMRh compared with IFTA and normal histology cases (p = 0.006 and 0.003), without differences in other non-HLA antibodies. Only three ABMRhDSAneg cases showed non-HLA antibodies. ABMRhDSAneg and ABMRhDSApos cases showed similar biopsy changes and graft-survival. Both total class II and DRB1 HLA-EM were associated with ABMRhDSApos but not with ABMRhDSAneg. Multivariate analysis showed that pre-transplant HLA-DSA (OR: 3.69 [1.31-10.37], p = 0.013) and AT1R-Ab (OR: 5.47 [1.78-16.76], p = 0.003) were independent predictors of ABMRhDSApos.

Conclusions

In conclusion, pre-transplant AT1R-Ab is frequently found in ABMRhDSApos patients. However, AT1R-Ab, MICA-Ab, ETAR-Ab or EC-XM+ are rarely found among ABMRhDSAneg patients. Pre-transplant AT1R-Ab may act synergistically with preformed or de novo HLA-DSA to produce ABMRhDSApos but not ABMRhDSAneg. HLA epitope mismatch associates with ABMRhDSApos compared with ABMRhDSAneg, suggesting factors other than HLA are responsible for the damage.

FC 128NON-HLA ANTIBODIES AND EPLET MISMATCHES IN KIDNEY TRANSPLANT RECIPIENTS WITH A HISTOLOGICAL PICTURE OF ANTIBODY-MEDIATED REJECTION WITH AND WITHOUT HLA DONOR-SPECIFIC ANTIBODIES

Background and Aims

Correlation between antibody-mediated rejection (ABMR) and HLA donor-specific antibodies (DSA) is strong but imperfect in kidney transplant (KT) recipients, raising the possibility of other detrimental antibodies contributing to ABMR. The role of non-HLA antibodies on outcomes is not well known.

Method

We retrospectively assessed KT biopsies scored according to Banff’15 classification. Pre- and post-KT serum samples were checked for HLA and non-HLA antibodies (MICA-Ab, angiotensin II type 1 receptor (AT1R)-Ab, endothelin-1 type A receptor (ETAR)-Ab and crossmatches with primary aortic endothelial cells (EC-XM)). We also analyzed HLA epitope mismatches between donors and recipients.

Results

One-hundred eighteen patients with normal (n=19), ABMR histology (n=52) or IFTA (n=47) in their biopsy were studied. Graft survival was worse in ABMR patients (p=0.003). Pre-KT HLA-DSA were more frequent in ABMR cases (p=0.006). At biopsy, 73% ABMR patients had HLA-DSA (p&lt;0.001). Pre-KT AT1R-Ab were more frequent in ABMR compared with IFTA and normal cases (p=0.003), without differences in other non-HLA antibodies. Fourteen patients with histological ABMR (27%) had no detectable HLA-DSA post-KT and only 3 had non-HLA Ab. However, these ABMR-DSA- cases showed similar biopsy changes and graft survival compared with ABMR-DSA+. Pre- or post-KT non-HLA antibodies other than AT1R-Ab were detected similarly in ABMR and in normal or IFTA cases. Both total class II and DRB1 epitope mismatches were associated with postransplant DSA and ABMR-DSA+. Multivariate analysis showed that both pre-KT HLA-DSA and AT1R-Ab (DSA: OR: 3.39 [1.20-9.59], p=0.021; AT1R-Ab: OR: 5.31 [1.75-16.10], p=0.003) were strong independent predictors of postransplant ABMR-DSA+ (Table 1).

Conclusion

Despite highly prevalent HLA-DSA before and after transplantation in KT with histological ABMR, 27% of cases did not show circulating HLA-DSA. Pre-KT AT1R-Ab associated with ABMR-DSA+, but not MICA-Ab, ETAR-Ab or EC-XM+. Any of them associated significantly with ABMR-DSA-. Epitope mismatch predicted both postransplant DRB-DSA and ABMR-DSA+. Detection of pre-KT HLA-DSA and/or AT1R-Ab, together with HLA epitope mismatch assessment, are valuable tools for better DSA and ABMR prediction in KT patients.

Activation of final complement components after kidney transplantation as a marker of delayed graft function severity

Background

Ischaemia-reperfusion (I/R) damage is a relevant cause of delayed graft function (DGF). Complement activation is involved in experimental I/R injury, but few data are available from kidney transplant (KT) patients. We studied the dynamics of membrane attack complex (C5b-9) as a soluble fraction (SC5b-9) and the histological deposit pattern of C3b, complement Factor H (FH) and C5b-9 in DGF patients.

Methods

We evaluated SC5b-9 levels in 59 recipients: 38 with immediate graft function and 21 with DGF. The SC5b-9 was measured at admission for KT and 7 days after KT. DGF-kidney biopsies (n = 12) and a control group of 1-year protocol biopsies without tissue damage (n = 4) were stained for C5b-9, C3b and FH.

Results

SC5b-9 increased significantly in DGF patients (Day 0: 6621 ± 2202 mAU/L versus Day 7: 9626 ± 4142  mAU/L; P = 0.006), while it remained stable in non-DGF patients. Days 0-7 increase >5% was the better cut-off associated with DGF versus non-DGF patient discrimination (sensitivity = 81%). In addition, SC5b-9 increase was related to DGF duration and worse graft function, and independently associated with DGF occurrence. SC5b-9, C3b and FH stains were observed in tubular epithelial cells basal membrane. DGF-kidney biopsies showed a more frequently high-intensity stain, a higher number of tubules with positive stain and larger perimeter of tubules with positive stains for SC5b-9, C3b and FH than control patients.

Conclusions

Both SC5b-9 levels and SC5b-9, C3b and FH deposits in tubular epithelial cells basal membrane are highly expressed in patients experiencing DGF. SC5b-9 levels increase could be useful as a marker of DGF severity.

P0185ROLE OF THE COMPLEMENT SYSTEM IN PROLIFERATIVE LUPUS NEPHRITIS

Background and Aims

Lupus Nephritis (LN) is a serious complication in patients with Systemic Lupus Erythematosus (SLE) which confers a worse prognosis in patients that develop this condition. It is well known that histological lesions correlate poorly with the prognosis of the disease, but little is known about the role of complement proteins deposition in kidney tissue. The aim of this study was to evaluate the effect on renal manifestations of the deposition in renal tissue of C3, as a marker of alternative pathway, C4 as a marker of the classical pathway and C1q representing the lectin pathway.

Method

A retrospective observational study was performed, including native kidney biopsies with a diagnosis of lupus proliferative nephritis (class III/IV) (ISN/RPS 2003). Direct immunofluorescence microscopy was performed in -80ºC frozen sections to evaluate IgA, IgG, IgM, C4d, C1q and C3, and LES activity and chronicity scores were calculated according to NIH disease activity scoring system. The intensity of staining was graded as 0 (no staining), +1 (stainvisible at 40X magnification), +2 (at 20X), +3 (at X10), and +4 (at 2-4X). For statistical purpose we considered weak staining: 0, +1, +2 and strong staining: +3, +4. Patient´s files were retrospectively reviewed and clinical and analytical data were collected using a standardized form.

Results

64 native kidney biopsies from 56 patients with a diagnosis of lupus proliferative nephritis were included, basal characteristics are described in attached Table. Activity index was significantly higher in biopsies showing strong intensity C3 staining compared to biopsies showing weak intensity C3 staining [(n=25) 10±1 vs (n=13) 5±1; p=0.002 respectively], alb/creat was significantly higher in patients in whom biopsy showed strong intensity C3 staining, compared to biopsies showing weak intensity C3 staining [(n=10) 1964.4±585.2 mg/gr vs (n=6) 823.6±58 mg/gr; p&lt;0.001, respectively], prot/creat was significantly higher in biopsies that showed strong C3 staining intensity [(n=27) 2302.5±325 mg/gr vs (n=12) 1287.7±235 mg/gr, p&lt;0.005, respectively], haematuria at NL diagnosis was more frequently in patients whose biopsy showed strong intensity C3 staining (n=21, 80.8%), compared to biopsies showing weak intensity C3 staining (n=5, 19.5%, p&lt;0.001); most of the patients without haematuria at diagnosis showed a weak intensity C3 staining or not C3 staining (n=13, 62%). Endocapillary proliferation was significantly higher in biopsies showing strong intensity C3 staining (90.9% vs 9.1%, p&lt;0.001).Time to proteinuria response is higher in patients showing strong intensity C4d stainingcompared with biopsies showing weak intensity C4d staining (15.2±2.4 vs 6.4±1.8 months; p=0.001), time to haematuria response is higher inbiopsies showing strong intensity C4d staining (19.5±5.5 vs 7.5±2.3 months, p=0.003). Time to proteinuria response is higher in patients showing strong intensity C1q stainingcompared to biopsies showing weak intensity C1q staining (14.0±9 vs 3.3±2.6 months, p &lt;0.001).

Conclusion

Our results suggest that complement system is activated in kidney tissue of proliferative LN patients; C3 staining is associated with clinical, analytical and histological data related to acute lupus activity, whereas C4d and C1q staining are related with long-term outcomes like treatment response. Further studies are needed to elucidate the role of complement system in LN.

P1602MICROVASCULAR INFLAMMATION WITHOUT DSA OR C4D: AN ORPHAN CATEGORY IN BANFF CLASSIFICATION WITH INTENSE CAPILLARITIS AND CYTOTOXIC T-CELL INFILTRATION

Background and Aims

Antibody-mediated rejection (ABMR) associated with donor-specific HLA antibodies (DSA) is the leading cause of late allograft failure after kidney transplantation. Microvascular inflammation (MVI) without detectable circulating DSA or C4d + cannot be classified as ABMR according to Banff-2017. The involvement of intragraft lymphocyte subsets in the development of humoral damage in kidney transplantation (KT) is relevant. We aimed to analyze lymphocyte subset distribution in kidney transplant biopsies (KTBx) with ABMR compared with MVI and with normal KTBx.

Method

KTBx with ABMR, MVI (g+ptc≥2, without DSA) or normal findings were included. DSA were identified with Luminex single antigen assays. Intragraft lymphocyte subsets’ characterization was performed by immunohistochemistry: T-lymphocytes (CD3, CD4, CD8, Foxp3), B-lymphocytes / plasmatic cells (CD20, CD138), NK cells (CD56), macrophages / monocytes (CD68), cytotoxic cells (TIA1) and activated cells (PD1) were evaluated.

Results

We analyzed 34 KTBx: 21 ABMR, 5 MVI and 8 KTBx with normal findings. KT with ABMR and MVI had more proteinuria at the time of the biopsy compared with the normal group (575 mg/24h and 964 mg/24h vs 147 mg/24h, p=0.002 and p=0.005 respectively). DSA were more frequently detected in patients with ABMR (95.2% vs 0% and 37.5%, p&lt;0.001 and p=0.003 respectively). KTBx with ABMR and MVI had increased cytotoxic T-cell infiltration apparently corresponding to NK cells in peritubular capillaries (ptc) compared to normal group. Moreover, both groups showed a greater number of macrophages and monocytes in glomeruli. KT with MVI but not with ABMR had a significantly increased activated cell infiltration (PD1+) in ptc compared to the normal group, and showed an increased cytotoxic T-cell infiltration in glomeruli compared to ABMR and normal groups.

Conclusion

ABMR and MVI have an increased infiltration of NK cells with cytotoxic activity in ptc that differs from the normal group. However, KT with MVI show greater infiltration of activated cells in ptc and cytotoxic T-cell in glomeruli compared to ABMR suggesting the possibility of different activation pathways.

P1601COMPLEMENT MEMBRANE ATTACK COMPLEX DURING THE FIRST WEEK AFTER KIDNEY TRANSPLANTATION AS SEVERITY BIOMARKER TO DELAYED GRAFT FUNCTION

Background and Aims

Ischemia-reperfusion (I/R) damage is a relevant cause of delayed graft function (DGF). Complement activation is involved in experimental I/R injury, but few data are available about the expression of the complement cascade final component -membrane attack complex (MAC)- and I/R injury in KT patients. We studied the dynamics of membrane attack complex (MAC) as plasma fraction (pMAC) and the histological deposit pattern of C3b, complement factor H (FH) and MAC in DGF patients.

Method

We evaluated pMAC levels in 59 recipients, 38 with immediate graft function and 21 without serum creatinine decreased at day 7 (DGF). pMAC was measured at admission for KT (day 0) and 7 days after KT (day 7). Sandwich ELISAs were used to measure MAC. Additionally, we performed imunohistoquimical stained for MAC, C3b and kidney biopsies (KB) with DGF (n=12) and a control group of one-year protocol biopsies without damage (n=4)

Results

Patients in the DGF group were older, more frequently diabetics and received kidneys from older donors and more frequently controlled cardio-circulatory death type.

Day0 and day7 post-KT pMAC levels were similar in non-DGF patients 5902±3049 mAu/L vs 6178±2882 mAu/L; p=0.686). However, patients with DGF showed a significant increase of pMAC levels between day0 and day7 (6621±2202 mAu/L vs 9625±4142 mAu/L; p=0.006. Figure 1

Percentage pMAC levels increase (Δ0-7 pMAC%) discriminative assessment analyzed by ROC curve showed a good discriminative value for DGF with an AUC of 0.78; p&lt;0.001 (sensitivity 81%, specificity 66% by cut-off point of 5%). In patients with DGF longer than ten days, we found more frequently patients with a Δ0-7 pMAC &gt;5% (83% vs 17% Δ0-7 pMAC &lt;5% ; p=0.003).Patients with DGF showed renal function at 3 and 6 months, but worse renal function 1 year after KT (serum creatinine 1.78±0.61 vs 1.35±0.30 mg/dl in non-DGF patients). DGF patients with Δ0-7 pMAC &gt;5% displayed worse renal function 1 and 2 year after KT compared to DGF patients with Δ0-7 pMAC &lt;5%.

MAC, C3b and FH stains were observed in tubular epithelial cells basal membrane. DGF-kidney biopsies showed more frequently high-intensity stain for MAC and FH than controls, without differences to C3b stain. DGF-kidney biopsies also showed a higher number of tubules with positive stain and larger perimeter of tubules with positive stains for MAC, C3b and FH than the controls. Figure 2.

Among the 12 patients with DGF-biopsies, three (25%) never recovered renal function, all of them presented Δ0-7 pMAC &gt;5% and intense, diffuse and positive staining in more than 50% of tubular perimeter for MAC, FH and C3b

Conclusion

Complement activation during peritrasplant period could be related with the severity of graft injury and the presence of DGF. Therefore, the determination of MAC levels could be useful to identify patients with possible complement dependent graft injury that might benefit from complement inhibitor therapies

Risk Factors Associated with Major Complications after Ultrasound-Guided Percutaneous Renal Biopsy of Native Kidneys

INTRODUCTION

Percutaneous renal biopsy (PRB) of native kidneys is an important tool for diagnosis and management of renal disease. In this study, we analyzed the success, safety, and risk complications of PRB in our center.

METHODS

A retrospective review of ultrasound-guided PRB done at our institution from January 1998 to December 2017 was performed. Clinical and laboratory data were collected for 661 PRBs. Statistical analysis was performed using the Mann-Whitney U test for continuous variable and chi-square test for categorical variables. Multivariate analysis using logistic regression was performed to assess factors associated with increased risk of complications after PRB.

RESULTS

The median age was 56 (42-68) years old, the majority were male (64%) and white (82%). Ten glomeruli were present in 63.5% of PRBs. Overall, the rate of complications was 16.6%, where 15.1% of them were minor complications and 1.5% were major complications. Perinephritic hematoma accounted for the minor complication that occurred most frequently, whereas the need of a blood transfusion was the prevalent for major complications. By multivariate analysis, increased activated partial thromboplastin time (aPTT; OR 1.11, 95% CI 1.035-1.180) and prebiopsy lower hemoglobin (Hgb; OR 1.61, 95% CI 1.086-2.304) were identified as independent risk factors for major complications. In addition, older patients (OR 1.057, 95% CI 1.001-1.117) were identified as an independent risk factor for blood transfusion requirement.

CONCLUSION

The current risk of complications after native PRB is low. Major complications are most common in case of increased aPTT and decreased Hgb baseline level.

Podocyte and tubular involvement in AngioJet-induced kidney injury

The AngioJet technique combines localized thrombolysis and percutaneous mechanical thrombectomy (PMT). However, PMT may cause acute kidney injury (AKI), which has been ascribed to severe mechanical haemolysis, although no renal biopsies have been reported. We now report the first renal biopsy in a patient with AKI following PMT. There is histological evidence of haemoglobin (Hb)-induced tubular injury and podocyte stress characterized by intracellular Hb and staining for ferritin and hemo-oxygenase-1, suggestive of an adaptive response to oxidative stress. This confirms that Hb is involved in kidney cell injury and supports the existence of several different kidney cellular targets.

A Myxoid Fibrotic Reaction Pattern is Associated with Metastatic Risk in Cutaneous Squamous Cell Carcinoma

Although desmoplasia has been associated with poor prognoses in cutaneous squamous cell carcinoma, little attention has been paid to the patterns of fibrosis. This study aimed to examine the different stromal fibrotic patterns as markers of metastatic risk. We performed a multicenter retrospective study that included 102 cutaneous squamous cell carcinomas (52 non-metastatic and 50 metastatic carcinomas). Clinical and histopathological data were registered. The fibrotic reaction pattern was classified as mature, intermediate or immature depending on the presence of keloid-like collagen and myxoid stroma. The immature pattern (areas characterized by myxoid changes with no inflammation) was observed in 18 samples and its presence was significantly associated with immunosuppression, budding, desmoplasia, perineural invasion, anatomic level, tumoural depth and metastatic risk in the multivariate analysis. Our findings suggest that the presence of an immature myxoid fibrotic pattern, which can be easily identified by routine hematoxylin-eosin staining, is strongly associated with metastatic risk.

The Polycomb proteins RING1B and EZH2 repress the tumoral pro-inflammatory function in metastasizing primary cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common malignancy in humans and approximately 5% metastasize, usually to regional lymph nodes. Epigenetic regulation of gene expression may allow tumoral cells to acquire new functions in order to escape from the primary tumor. The aim of this study was to investigate the expression and function of proteins of the Polycomb family of epigenetic regulators in the metastatic process of cSCC. A higher expression of RING1B and EZH2 was detected by immunohistochemistry in a series of primary cSCC tumors that metastasized (MSCCs) when compared with non-metastasizing cSCCs (non-MSCCs). Stable downregulation of RING1B and EZH2 in cSCC cells results in enhanced expression of inflammatory cytokines and activation of the NF-κB signaling pathway. Accordingly, non-MSCCs display higher levels of membranous pS176-inhibitor of NF-kB kinase, and their stroma is enriched in neutrophils and eosinophils when compared with MSCCs. In vitro, hematopoietic cells exhibit a substantial migratory response to supernatants from Polycomb-depleted cSCC cells. Altogether, these data indicate that RING1B and EZH2 repress the innate inflammatory cSCC function and impair tumor immunosurveillance and suggest that patients with high-risk cSCCs could benefit from clinical therapies addressed to harness the immune response.

Sex dimorphism in ANGII-mediated crosstalk between ACE2 and ACE in diabetic nephropathy

Angiotensin-converting enzyme (ACE) and ACE2 play a critical role in the renin-angiotensin system (RAS) by altering angiotensin II (ANGII) levels, thus governing its deleterious effects. Both enzymes are altered by sex and diabetes, and play an important role in the development of diabetic nephropathy (DN). Importantly, previous evidence in diabetic and ACE2-deficient (ACE2KO) males suggest a sex-dependent crosstalk between renal ACE and ACE2. In the present work, we aimed to study the sex-specific susceptibility to diabetes and direct infusion of ANGII in kidney disease progression, with a special focus on its link to ACE2 and ACE. In our mouse model, ANGII promoted hypertension, albuminuria, reduced glomerular filtration, and glomerular histological alterations. ANGII adverse effects were accentuated by diabetes and ACE2 deficiency, in a sex-dependent fashion: ACE2 deficiency accentuated ANGII-induced hypertension, albuminuria, and glomerular hypertrophy in diabetic females, whereas in diabetic males exacerbated ANGII-mediated glomerular hypertrophy, mesangial expansion, and podocyte loss. At the molecular level, ANGII downregulated renal ACE gene and enzymatic activity levels, as well as renin gene expression in ACE2KO mice. Interestingly, male sex and diabetes accentuated this effect. Here we show sex dimorphism in the severity of diabetes- and ANGII-related renal lesions, and demonstrate that ACE2- and ACE-related compensatory mechanisms are sex-specific. Supporting our previous findings, the modulation and ANGII-mediated crosstalk between ACE2 and ACE in DN progression was more evident in males. This work increases the understanding of the sex-specific role of ACE2 and ACE in DN, reinforcing the necessity of more personalized treatments targeting RAS.

Impact of persistent and cleared preformed HLA DSA on kidney transplant outcomes

Preformed HLA donor-specific antibodies (DSA) only detected with Luminex have been associated with increased risk of antibody-mediated rejection (ABMR) and graft failure after kidney transplantation (KT). Their evolution after KT may modify this risk. We analyzed postransplant evolution of preformed DSA identified retrospectively and their impact on outcomes of 370 KT performed 2006-2014. Antibodies were monitored prospectively at 1-3-5 years after KT and if any dysfunction. Early acute ABMR was more frequent among patients with preformed DSA class-I or I + II than isolated class-II (29.4% vs 4.5%, p = 0.02). One year post-KT, 20 of 34 patients with functioning KT had persistent DSA. Preformed DSA class-II persisted more frequently than class-I/I + II (66.7% vs 33.3%; p = 0.031). The only risk factor independently associated with persistence was pretransplant MFI. Patients with de novo DSA had the highest risk of ABMR (HR 22.2 [CI 6.1-81.2]). Although recipients with persisting preformed DSA had significantly increased ABMR risk (HR 14.7 [CI 6.5-33.0]), those with cleared preformed DSA also had a higher risk than those without DSA (HR 7.01 [CI 2.2-21.8]). Preformed DSA are a very important risk factor for ABMR and graft loss. Patients who clear preformed DSA still show an increased risk of ABMR and graft loss after KT.

Mucormycosis: an unusual cause of gastric perforation and severe bleeding in immunocompetent patients

Mucormycosis is a rare and often fatal opportunistic infection that especially occurs in immunocompromised patients. Primary gastrointestinal infection is uncommon and accounts for only approximately 7% of all cases of mucormycosis but it is associated with an 85% mortality rate due to perforation and massive bleeding. Very few cases of gastrointestinal mucormycosis in an immunocompetent host have been reported. We describe a case of gastric necrosis and massive bleeding due to fulminant invasive mucormycosis.

CD274 (PDL1) and JAK2 genomic amplifications in pulmonary squamous-cell and adenocarcinoma patients

AIMS

CD274 (PDL1) and JAK2 (9p24.1) gene amplifications have been recently described in pulmonary carcinomas in association with programmed death-ligand 1 (PD-L1) expression. Furthermore, PTEN loss has been explored preclinically in relation to PD-L1 expression. Our aim was to determine whether these genomic alterations affect PD-L1 expression levels in non-small-cell lung cancer.

METHODS AND RESULTS

PD-L1 and PTEN expression determined by immunohistochemistry (IHC), and CD274, JAK2 and PTEN copy number alterations (CNAs) determined by fluorescence in-situ hybridisation, were studied in 171 pulmonary carcinoma specimens. PD-L1 expression was positive in 40 cases (23.3%), and CD274 amplification was present in 14 tumours (8.8%). Concordance between both events was found in 12 of 14 amplified cases (P = 0.0001). We found nine JAK2-amplified cases (5.7%), seven with PD-L1 expression (P = 0.0006). Moreover, six of the seven cases had JAK2 and CD274 coamplification (9p24.1 genomic amplification). Remarkably, the average PD-L1 IHC score was higher in these amplified cases (230 versus 80; P = 0.001). Non-statistical associations were observed between PD-L1 expression and PTEN loss and PTEN deletions.

CONCLUSIONS

We describe a subset of patients (8.2%) who had 9p24.1 amplifications resulting in high expression of PD-L1. Our results provide evidence for genomic up-regulation of PD-L1 expression in non-small-cell lung cancer.

Impact of anthropometric features on the applicability and accuracy of FibroScan® (M and XL) in overweight/obese patients

BACKGROUND AND AIM

Transient elastography is the reference method for liver stiffness measurement (LSM) in the general population, having lower applicability in obese patients. We evaluated the applicability and diagnostic accuracy of the M and XL probes in overweight/obese patients to establish the most appropriate approach.

METHODS

From May 2013 to March 2015, we evaluated patients with a body mass index (BMI) ≥ 28 kg/m² . We constructed an algorithm with variables independently related to unreliable LSM with the M probe.

RESULTS

A total of 1084 patients were evaluated. M and XL probe applicability was 88.8% and 98%, respectively. Waist circumference (WC) (OR; 95% CI; P) (0.97; 0.94-0.99; P < 0.001) and skin-capsule distance (SCD) (0.83; 0.79-0.87; P < 0.001) were independently related to unreliable LSM (M probe). The SCD was > 25 mm in 5.5% of individuals with a BMI ≤ 35 kg/m² and a WC ≤ 117 cm, with LSM (M probe) applicability rising to 94.3%. In contrast, 36.9% of patients with a BMI > 35 kg/m² and/or a WC > 117 cm presented an SCD > 25 mm, with M probe applicability being 73.1%. The diagnostic accuracy (area under the receiver operator characteristic) using the M probe to identify significant steatosis (0.76), fibrosis (0.89), and cirrhosis (0.96) was very high in patients with a BMI ≤ 35 kg/m² and a WC ≤ 117 cm.

CONCLUSIONS

The applicability and accuracy of the FibroScan^® M probe to identify fibrosis and steatosis was excellent in overweight and obesity grade I (BMI ≤ 35 kg/m² ) with a WC ≤ 117 cm. The XL probe increased the applicability of transient elastography in obesity grade II-III (BMI > 35 kg/m² ).

ROS1 copy number alterations are frequent in non-small cell lung cancer

Objectives

We aimed to determine the prevalence and partners of ROS1 rearrangements, to explore the correlation between FISH and IHC assays, and to investigate clinical implications of ROS1 copy number alterations (CNAs).

Methods

A total of 314 NSCLC patients were screened using ROS1 FISH break-apart probes. Of these, 47 surgical tumors were included in TMAs to analyze ROS1 heterogeneity assessed either by FISH and IHC, and chromosome 6 aneusomy. To characterize ROS1 partners, probes for CD74, EZR, SLC34A2 and SDC3 genes were developed. ROS1 positive FISH cases were screened also by IHC.

Results

Five patients were ROS1 positive (1.8%). We identified two known fusion partners in three patients: CD74 and SLC34A2. Four out of five ROS1 rearranged patients were female, never smokers and with adenocarcinoma histology. Rearranged cases were also positive by IHC as well. According to ROS1 CNAs, we found a prevalence of 37.8% gains/amplifications and 25.1% deletions.

Conclusions

This study point out the high prevalence of ROS1 CNAs in a large series of NSCLC. ROS1 gains, amplifications and deletions, most of them due to chromosome 6 polysomy or monosomy, were heterogeneous within a tumor and had no impact on overall survival.

Renal graft survival according to Banff 2013 classification in indication biopsies

INTRODUCTION

The impact of acute rejection in kidney graft survival is well known, but the prognosis of other diagnoses is uncertain. We evaluated the frequency and impact on graft survival of different diagnostic categories according to the Banff 2013 classification in a cohort of renal transplant recipients.

MATERIAL AND METHODS

Retrospective study of 495 renal biopsies by indication in 322 patients from 1990-2014. Two independent observers reviewed the histological reports, reclassifying according to the Banff 2013 classification.

RESULTS

Of 495 biopsies, 28 (5.7%) were not diagnostic. Of the remaining 467, 10.3% were «normal» (category 1), 19.6% antibody-mediated changes (category 2), 5.9% «borderline» changes (category 3), 8.7% T-cell-mediated rejection (category 4), 23.4% interstitial fibrosis/tubular atrophy (IFTA) (category 5) and 26.5% with other diagnoses (category 6). As time after transplantation increases, diagnoses of categories 1, 3 and 4 decrease, while categories 5 and 2 increase. Worse graft survival with category 2 diagnosis was observed (45% at 7.5 years, HR 4.29 graft loss [95% CI, 2.39-7.73]; P≤.001, compared to category 1). Grafts with «unfavourable histology» (chronic antibody-mediated rejection, moderate-severe IFTA) presented worse survival that grafts with «favourable histology» (normal, acute tubular necrosis, mild IFTA).

CONCLUSIONS

The Banff 2013 classification facilitates a histological diagnosis in 95% of indication biopsies. While diagnostic category 6 is the most common, a change in the predominant histopathology was observed according to time elapsed since transplantation. Antibody-mediated changes are associated with worse graft survival.

Predictive factors for non-diabetic nephropathy in diabetic patients. The utility of renal biopsy

BACKGROUND AND OBJECTIVES

Diabetic renal lesions can only be diagnosed by kidney biopsy. These biopsies have a high prevalence of non-diabetic lesions. The aims of the study were to determine the predictability of non-diabetic nephropathy (NDN) in diabetics and study differences in survival and renal prognosis. In addition, we evaluated histological lesions and the effect of proteinuria on survival and renal prognosis in patients with diabetic nephropathy (DN).

MATERIAL AND METHODS

A descriptive, retrospective study of kidney biopsies of diabetics between 1990 and 2013 in our centre.

RESULTS

110 patients were included in the study: 87 men (79%), mean age 62 years (50-74), mean serum creatinine 2.6mg/dl (0.9-4.3) and proteinuria 3.5g/24hours (0.5-6.5). 61.8% showed NDN, 34.5% showed DN and 3,6% showed DN+NDN. The most common NDN was IgA nephropathy (13,2%). In the multivariate analysis, creatinine (OR: 1.48, 1.011-2.172, p=0.044), proteinuria/24hours (OR: 0.813, 0.679-0.974, p=0.025), duration of diabetes (OR: 0.992, 0.987-0.998, p=0.004), age (OR: 1.068, 95% CI: 1.010-1.129, p=0.022), and diabetic retinopathy (OR: 0.23, 0.066-0.808, p=0.022) were independently associated with NDN. We did not find any differences in survival or renal prognosis. Concerning patients with DN, increased nodular mesangial expansion (p=0.02) and worse renal prognosis (p=0.004) were observed in nephrotic proteinuria as compared to non-nephrotic proteinuria. We did not find differences in patient survival.

CONCLUSIONS

The most common cause of NDN was IgA nephropathy. Higher creatinine levels, shorter duration of diabetes, absence of diabetic retinopathy, lower proteinuria, and older age were risk factors for NDN. Patients with DN and nephrotic-range proteinuria had worse renal prognosis.

Current and Future Research Methods in Strategic Management

Early work in strategic management emphasized single case studies, followed by research on corporate diversification strategy, firm heterogeneity, strategic groups, and generic business strategies. Intermediate work added the foci of environmental determinants and strategic choice, often using secondary data from large, multi-industry firm samples. Recently, the most prominent new theoretical paradigm is the resource-based view of the firm, using smaller sample studies. Future research is likely to integrate and contrast multiple theories and to develop more fine-grained and complex models. Quantitative research will emphasize longitudinal data, dynamic analysis, and greater focus on specific strategic decisions/actions. Future research will use more specialized tools such as panel data analysis, dynamic models of partial adjustment, logistic and Poisson regression analyses, event history analysis, network analysis, and structural equation modeling. Nontraditional research designs will also gain popularity, such as combined qualitative/quantitative data approaches and comparison of outliers.

Impact of the Banff 2013 classification on the diagnosis of suspicious versus conclusive late antibody-mediated rejection in allografts without acute dysfunction

BACKGROUND

The Banff classification is used worldwide to characterize pathological findings in renal allograft biopsies. During the 11th Banff meeting, relevant changes were introduced in the diagnostic criteria for Category 2 antibody-mediated rejection (ABMR). Here, we assess the effect of these changes on the diagnosis of late chronic ABMR.

METHODS

Seventy-three indication renal graft biopsies (chronic dysfunction, proteinuria and/or the presence of de novo donor-specific antibodies) from 68 kidney transplant recipients initially classified following the Banff 2009 criteria were reviewed and reclassified as per the new Banff 2013 criteria.

RESULTS

The diagnostic category changed in 18% of the study biopsies with Banff 2013. The reclassification mainly involved Category 2 cases, from which 23.5% of the biopsies from older patients with worse graft function were overlooked by Banff 2009. ABMR was ruled out in 13% of cases under the Banff 2009 criteria. A significant number of the study samples were conclusively diagnosed as ABMR (40% as per Banff 2009 and 74% as per Banff 2013; P = 0.006), because of the inclusion of microvascular inflammation and the acceptance of some ultrastructural diagnostic criteria. However, when following the criteria of the new classification, samples with histological signs of chronic ABMR, in which human leucocyte antigen donor-specific antibodies are not detected or ultrastructural studies are not performed, may be inadequately characterized.

CONCLUSIONS

The Banff 2013 classification helps in making a diagnosis of late ABMR, identifying cases, decreasing the percentage of suspected ABMR and making more conclusive diagnoses.