Chemokine CXCL13 as a New Systemic Biomarker for B-Cell Involvement in Acute T Cell-Mediated Kidney Allograft Rejection

Proteomic Profiles of Maternal Plasma Extracellular Vesicles for Prediction of Preeclampsia

PROBLEM

Preeclampsia is a heterogeneous syndrome of diverse etiologies and molecular pathways leading to distinct clinical subtypes. Herein, we aimed to characterize the extracellular vesicle (EV)-associated and soluble fractions of the maternal plasma proteome in patients with preeclampsia and to assess their value for disease prediction.

METHOD OF STUDY

This case-control study included 24 women with term preeclampsia, 23 women with preterm preeclampsia, and 94 healthy pregnant controls. Blood samples were collected from cases on average 7 weeks before the diagnosis of preeclampsia and were matched to control samples. Soluble and EV fractions were separated from maternal plasma; EVs were confirmed by cryo-EM, NanoSight, and flow cytometry; and 82 proteins were analyzed with bead-based, multiplexed immunoassays. Quantile regression analysis and random forest models were implemented to evaluate protein concentration differences and their predictive accuracy. Preeclampsia subgroups defined by molecular profiles were identified by hierarchical cluster analysis. Significance was set at p < 0.05 or false discovery rate-adjusted q < 0.1.

RESULTS

In preterm preeclampsia, PlGF, PTX3, and VEGFR-1 displayed differential abundance in both soluble and EV fractions, whereas angiogenin, CD40L, endoglin, galectin-1, IL-27, CCL19, and TIMP1 were changed only in the soluble fraction (q < 0.1). The direction of changes in the EV fraction was consistent with that in the soluble fraction for nine proteins. In term preeclampsia, CCL3 had increased abundance in both fractions (q < 0.1). The combined EV and soluble fraction proteomic profiles predicted preterm and term preeclampsia with an AUC of 78% (95% CI, 66%-90%) and 68% (95% CI, 56%-80%), respectively. Three clusters of preeclampsia featuring distinct clinical characteristics and placental pathology were identified based on combined protein data.

CONCLUSIONS

Our findings reveal distinct alterations of the maternal EV-associated and soluble plasma proteome in preterm and term preeclampsia and identify molecular subgroups of patients with distinct clinical and placental histopathologic features.

Case report: Bruton tyrosine kinase inhibitor as therapy for chronic lymphocytic leukemia infiltrating a kidney allograft

The burden of chronic lymphocytic leukemia (CLL) in the prognosis of solid organ transplant (SOT) recipients seems non-negligible. Whether transplanting a patient with previous CLL is safe or what is the optimal monitoring and treatment management after transplantation is still unclear and only based on few case series and reports. Therefore, we aimed to contribute to this understanding by reporting the first documented case of a clinically significant CLL with biopsy-proven infiltration of the kidney allograft and its successful management with a Bruton tyrosine kinase inhibitor (BTKi). We then reviewed the related literature, with a focus on CLL and kidney transplantation. Our main message is that BTKi may represent a safe and effective intervention to prevent the hazardous patient and graft outcomes of CLL in SOT patients.

Significance of Perivascular Aggregates in Kidney Allografts: Evaluation of 1-Year Protocol Biopsies Using Recent Banff Classification

BACKGROUND

Perivascular aggregates (PVAs) often occur in kidney allografts; however, their significance needs to be re-evaluated in light of changes in the concept and criteria of allograft rejection.

METHODS

We reviewed 1-year protocol biopsies in 258 patients with kidney transplants to identify PVAs and concurrent pathology based on the Banff 2017 classification, including revised criteria for chronic active T-cell mediated rejection (CA-TCMR). We investigated the incidence of PVA, concurrent allograft lesions, diagnosis, and graft survival. No prisoners were used in this study, and no participants were coerced or paid.

RESULTS

We identified PVA in 81 biopsies (31.4%). The incidence of previous rejection (32.1% vs 12.4%, P= .0003) and total inflammation (1.3 ± 0.8 vs 0.6 ± 0.8, P < .0001), inflammation (0.7 ± 0.8 vs 0.2 ± 0.5, P < .0001), inflammation in the area of interstitial fibrosis and tubular atrophy (1.3 ± 1.2 vs 0.7 ± 0.9, P < .0001), tubulitis (1.4 ± 1.1 vs 0.6 ± 0.9, P < .0001), and interstitial fibrosis scores (1.2 ± 0.9 vs 0.9 ± 0.9, P= .01) were higher in PVA-positive compared with patients with PVA-negative. Diagnoses in the PVA-positive group revealed no rejection in 49.4%, CA-TCMR in 21.0%, borderline changes in 18.5%, and acute TCMR in 6.2%. CA-TCMR was more frequent in patients with PVA-positive (21.0% vs 4.0%, P < .0001). Graft survival was similar in both groups among all patients, no-rejection, any type of rejection, and CA-TCMR subgroups.

CONCLUSIONS

PVAs occur heterogeneously and are associated with previous rejection or concurrent CA-TCMR. The prognostic significance of PVAs in kidney transplantation is inconclusive, and further investigations are needed.

The dynamic changes of monocytes and cytokines during wound healing post-burn injury

BACKGROUND

Burn injury is a sudden and traumatic injury that affects a large part of the population worldwide, who are placed at high risk of developing hypertrophic scars (HTS). HTS are a fibrotic scar resulting in painful contracted and raised scarring, affecting mobility in joints and work life, as well as cosmetically. The aim of this research was to enhance our understanding of the systematic response of monocytes and cytokines in wound healing after burn injury, in order to develop novel approaches to prevention and treatment of HTS.

METHODS

Twenty-seven burn patients and thirteen healthy individuals were recruited in this study. Burn patients were stratified by burn total body surface area (TBSA). Peripheral blood samples were taken post-burn injury. Serum and peripheral blood mononuclear cells (PBMCs) were separated from the blood samples. This research investigated cytokines IL-6, IL-8, IL1RA, IL-10, and chemokine pathways SDF-1/CXCR4, MCP-1/CCR2, RANTES/CCR5 during the wound healing process in burn patients with varying severity of injuries by using enzyme-linked immunosorbent assays. PBMCs were stained for monocytes and the chemokine receptors by flow cytometry. Statistical analysis was done by one-way ANOVA with a Tukey correction, and regression analysis was performed using Pearson's Correlation analysis.

RESULTS

The CD14⁺CD16^- monocyte subpopulation is larger in patients who developed HTS at 4-7 days. The CD14⁺CD16⁺ monocyte subpopulation is smaller in the first week of injury, where it is similar after 8 days. Burn injury increased CXCR4, CCR2, and CCR5 expressions in CD14⁺ CD16⁺ monocytes. Increases in MCP-1 at 0-3 days after burn injury was positively correlated with burn severity. IL-6, IL-8, RANTES, and MCP-1 significantly increased with increasing burn severity.

CONCLUSIONS

Monocytes and their chemokine receptors, as well as systemic levels of cytokines in wound healing of burn patients and scar development will require ongoing assessment to enhance our understanding of the abnormal wound healing after burn injury.

Renal Tissue Expression of BAFF and BAFF Receptors Is Associated with Proliferative Lupus Nephritis

Background: The B-cell activating factor (BAFF) controls the maturation and survival of B cells. An imbalance in this cytokine has been associated with systemic autoimmunity in SLE and lupus nephritis (LN). However, few investigations have evaluated the tissular expression of BAFF in LN. This study aimed to associate BAFF system expression at the tissular level with the proliferative LN classes. Methods: The analysis included eighteen kidney tissues, with sixteen LN (class III = 5, class IV = 6, class III/IV+V = 4, and class V = 1), and two controls. The tissular expression was evaluated with an immunochemistry assay. A Cytation5 imaging reader and ImageJ software were used to analyze the quantitative expression. A p-value < 0.05 was considered significant. Results: The expressions of BAFF, A proliferation-inducing ligand (APRIL), and their receptors were observed in glomerular, tubular, and interstitial zones, with BAFF being the most strongly expressed in the overall analysis. BAFF-Receptor (BR3), transmembrane activator and CALM interactor (TACI), and B-Cell maturation antigen (BCMA) displayed higher expressions in LN class IV in all zones analyzed (p < 0.05). Additionally, a positive correlation was found between APRIL, TACI, and BCMA at the glomerular level; BCMA and APRIL in the interstitial zone; and BR3, TACI, and BCMA in the tubule (p < 0.05). Conclusions: The expression of BAFF and BAFF receptors is mainly associated with LN class IV, emphasizing the participation of these receptors as an essential pathogenic factor in kidney involvement in SLE patients.

N6-methyladenosine regulators-related immune genes enable predict graft loss and discriminate T-cell mediate rejection in kidney transplantation biopsies for cause

Objective

The role of m6A modification in kidney transplant-associated immunity, especially in alloimmunity, still remains unknown. This study aims to explore the potential value of m6A-related immune genes in predicting graft loss and diagnosing T cell mediated rejection (TCMR), as well as the possible role they play in renal graft dysfunction.

Methods

Renal transplant-related cohorts and transcript expression data were obtained from the GEO database. First, we conducted correlation analysis in the discovery cohort to identify the m6A-related immune genes. Then, lasso regression and random forest were used respectively to build prediction models in the prognosis and diagnosis cohort, to predict graft loss and discriminate TCMR in dysfunctional renal grafts. Connectivity map (CMap) analysis was applied to identify potential therapeutic compounds for TCMR.

Results

The prognostic prediction model effectively predicts the prognosis and survival of renal grafts with clinical indications (P< 0.001) and applies to both rejection and non-rejection situations. The diagnostic prediction model discriminates TCMR in dysfunctional renal grafts with high accuracy (area under curve = 0.891). Meanwhile, the classifier score of the diagnostic model, as a continuity index, is positively correlated with the severity of main pathological injuries of TCMR. Furthermore, it is found that METTL3, FTO, WATP, and RBM15 are likely to play a pivotal part in the regulation of immune response in TCMR. By CMap analysis, several small molecular compounds are found to be able to reverse TCMR including fenoldopam, dextromethorphan, and so on.

Conclusions

Together, our findings explore the value of m6A-related immune genes in predicting the prognosis of renal grafts and diagnosis of TCMR.

Diagnostic Biomarkers and Immune Infiltration in Patients With T Cell-Mediated Rejection After Kidney Transplantation

T cell-mediated rejection (TCMR) is an important rejection type in kidney transplantation, characterized by T cells and macrophages infiltration. The application of bioinformatic analysis in genomic research has been widely used. In the present study, Microarray data was analyzed to identify the potential diagnostic markers of TCMR in kidney transplantation. Cell-type identification by estimating relative subsets of RNA transcript (CIBERSORT) was performed to determine the distribution of immune cell infiltration in the pathology. Totally 129 upregulated differently expressed genes (DEGs) and 378 downregulated DEGs were identified. The GO and KEGG results demonstrated that DEGs were mainly associated with pathways and diseases involved in immune response. The intersection of the two algorithms (PPI network and LASSO) contains three overlapping genes (CXCR6, CXCL13 and FCGR1A). After verification in GSE69677, only CXCR6 and CXCL13 were selected. Immune cells Infiltration analysis demonstrated that CXCR6 and CXCL13 were positively correlated with gamma delta T cells (p < 0.001), CD4⁺ memory activated T cells (p < 0.001), CD8⁺ T cells (p < 0.001) and M1 macrophages (p = 0.006), and negatively correlated with M2 macrophages (p < 0.001) and regulatory T cells (p < 0.001). Immunohistochemical staining and image analysis confirmed the overexpression of CXCR6 and CXCL13 in human allograft TCMR samples. CXCR6 and CXCL13 could be diagnostic biomarkers of TCMR and potential targets for immunotherapy in patients with TCMR.

An Antibody-Aptamer-Hybrid Lateral Flow Assay for Detection of CXCL9 in Antibody-Mediated Rejection after Kidney Transplantation

Chronic antibody-mediated rejection (AMR) is a key limiting factor for the clinical outcome of a kidney transplantation (Ktx), where early diagnosis and therapeutic intervention is needed. This study describes the identification of the biomarker CXC-motif chemokine ligand (CXCL) 9 as an indicator for AMR and presents a new aptamer-antibody-hybrid lateral flow assay (hybrid-LFA) for detection in urine. Biomarker evaluation included two independent cohorts of kidney transplant recipients (KTRs) from a protocol biopsy program and used subgroup comparisons according to BANFF-classifications. Plasma, urine and biopsy lysate samples were analyzed with a Luminex-based multiplex assay. The CXCL9-specific hybrid-LFA was developed based upon a specific rat antibody immobilized on a nitrocellulose-membrane and the coupling of a CXCL9-binding aptamer to gold nanoparticles. LFA performance was assessed according to receiver operating characteristic (ROC) analysis. Among 15 high-scored biomarkers according to a neural network analysis, significantly higher levels of CXCL9 were found in plasma and urine and biopsy lysates of KTRs with biopsy-proven AMR. The newly developed hybrid-LFA reached a sensitivity and specificity of 71% and an AUC of 0.79 for CXCL9. This point-of-care-test (POCT) improves early diagnosis-making in AMR after Ktx, especially in KTRs with undetermined status of donor-specific HLA-antibodies.

Use of Rituximab for persistent EBV DNAemia, and Its effect on donor-specific antibody development in pediatric renal transplant recipients: A case series

INTRODUCTION

Persistent EBV DNAemia (PEBV) is associated with late-onset PTLD. The efficacy of rituximab in PEBV is not conclusive. We monitored PEBV and DSA in pediatric kidney transplant patients with or without rituximab.

METHODS

13 PEBV patients received standard treatment with immunosuppression reduction and valganciclovir, with or without IVIG; 5/13 were further treated with rituximab.

RESULTS

All Rituximab-treated and 6/7 No-Rituximab patients were EBV seronegative at transplant and seroconverted post-transplant. Peak EBV PCR levels were lower in No-Rituximab than Rituximab patients and all No-Rituximab patients cleared PEBV after standard treatment. Additional 1-2 doses of rituximab reduced EBV PCR levels in all 5 Rituximab patients, 3 cleared PEBV. One No-Rituximab patient developed localized PLTD. None of Rituximab patients developed de novo DSA, while 4/8 No-Rituximab patients did: 2/4 had ABMR. 1/5 Rituximab and 5/8 No-Rituximab patients had acute rejection. There was no change in eGFR between pre-EBV DNAemia and follow-up in Rituximab patients, while reduction in No-Rituximab patients was found. There was no difference in graft and patient survival.

CONCLUSIONS

While early intervention with rituximab in pediatric patients with PEBV may reduce viral load and PTLD, we observed a slower development of de novo DSA, and rejection and maintenance of eGFR.

CXCL13 Is an Indicator of Germinal Center Activity and Alloantibody Formation Following Transplantation

Supplemental Digital Content is available in the text.

Donor-specific antibodies (DSA) are a recognized cause of allograft injury, yet biomarkers that indicate their development posttransplant or guide management are not available. CXCL13 (chemokine [C-X-C motif] ligand 1) is a chemoattractant produced within secondary lymphoid organs necessary for germinal center (GC) and alloantibody formation. Perturbations in serum CXCL13 levels have been associated with humoral immune activity. Therefore, CXCL13 may correlate with the formation of HLA antibodies following transplantation.

The significance of metalloproteinase 3 (MMP-3), chemokine CXC ligand 13 (CXCL-13) and complement component C5a in different stages of ANCA associated vasculitis

The aim of the study was to evaluate the significance of metalloproteinase 3 (MMP-3), chemokine CXC ligand 13 (CXCL-13) and complement component 5a (C5a) in different stages of ANCA associated vasculitis (AAV). 89 adults were included into the study. 28 patients with active AAV (Birmingham Vasculitis Activity Score, BVAS > 3) formed the Active Group. 24 individuals who were in remission after 6 months of induction therapy formed the Short R Group, while 34 patients with longitudinal remission formed the Long R Group. 28 patients without autoimmune diseases similar in terms of age, gender and stage of kidney disease formed the Control Group. Receiver operating characteristic curve analysis (ROC) was used to evaluate MMP-3, CXCL-13 and C5a as markers of the different phases of vasculitis. In ROC analysis, MMP-3, CXCL-13 and C5a presented a good ability in distinguishing active vasculitis (Active Group) from the Control Group (AUC > 0.8), whereas only CXCL-13 displayed potential ability in distinguishing active vasculitis (Active Group) from long term remission (Long R Group, AUC = 0.683). MMP-3 significantly and positively correlated with serum creatinine concentration (r = 0.51, p = 0.011; r = 0.44, p = 0.009; r =  −0.66, p < 0.001) and negatively with eGFR (r =  −0.5, p = 0.012; r =  −0.35, p = 0.039; r =  −0.63, p < 0.001) in the Short R, Long R and Control Groups. MMP-3, CXCL-13, C5a can be potential markers in differentiating an active phase of vasculitis from other pathologies. However they can be treated as complementary to the well-known markers. CXCL-13 seems to be a potential marker in distinguishing active vasculitis from long term remission. MMP-3 level can be related to kidney function expressed by eGFR, therefore its elevation should be interpreted with caution in patients with kidney failure.

Prediction of acute renal allograft rejection by combined HLA-G 14-bp insertion/deletion genotype analysis and detection of kidney injury molecule-1 and osteopontin in the peripheral blood

INTRODUCTION

Acute renal rejection usually fails to be diagnosed before the increase in the serum creatinine levels, and the resultant damage to the renal tissues occur in varying degrees. We hypothesized that the combined detection of human leucocyte antigen-G (HLA-G) 14-bp insertion/deletion genotypes and kidney injury molecule-1 (KIM-1) and osteopontin (OPN) levels in serum might facilitate the prediction of acute renal allograft rejections in kidney transplant recipients.

METHODS

HLA-G 14-bp insertion/deletion genotypes and the serum KIM-1 and OPN levels of 77 kidney transplant recipients were determined and compared before operation and on days 1, 4, and 7 after the operation (32 in acute rejection [AR] group and 45 in stable allograft function [STA] group). These 3 indicators were combined to establish a model for the early prediction of AR.

RESULTS

The KIM-1 levels in the serum of patients were significantly higher in the AR group than in the STA group. The area under the receiver operator characteristics (ROC) curve (AUC) of KIM-1 for the prediction of rejection was maximized on the1st day after operation, with a sensitivity of 84.4% and a specificity of 86.7%. The OPN levels in the serum of patients were significantly higher in the AR group than in the STA group only before operation and on the 7th day after operation. The AUC of OPN for the prediction of rejection was maximized on 7th day after operation, with a sensitivity of 68.8% and a specificity of 88.9%. The HLA-G + 14-bp allele frequency was also significantly higher in the AR group than in the STA group. The results of these three indicators were converted into a qualitative method. If any two of the three indicators show as positive, it was diagnosed as acute rejection, and it has the highest ability to predict acute rejection with a sensitivity and specificity of 84.38% and 91.11%, respectively.

CONCLUSIONS

The HLA-G 14-bp insertion/deletion genotype and KIM-1 and OPN levels in the patients' serum were significantly different between the AR and STA groups. The power of predicting acute renal allograft rejection could be improved by combined these three biomarkers.

Ischemia Reperfusion Injury Triggers CXCL13 Release and B-Cell Recruitment After Allogenic Kidney Transplantation

Ischemia reperfusion injury (IRI) is linked with inflammation in kidney transplantation (ktx). The chemokine CXCL13, also known as B lymphocyte chemoattractant, mediates recruitment of B cells within follicles of lymphoid tissues and has recently been identified as a biomarker for acute kidney allograft rejection. The goal of this study was to explore whether IRI contributes to the up-regulation of CXCL13 levels in ktx. It is demonstrated that systemic levels of CXCL13 were increased in mouse models of uni- and bilateral renal IRI, which correlated with the duration of IRI. Moreover, in unilateral renal IRI CXCL13 expression in ischemic kidneys was up-regulated. Immunohistochemical studies revealed infiltration of CD22+ B-cells and, single-cell RNA sequencing analysis a higher number of cells expressing the CXCL13 receptor CXCR5, in ischemic kidneys 7 days post IRI, respectively. The potential relevance of these findings was also evaluated in a mouse model of ktx. Increased levels of serum CXCL13 correlated with the lengths of cold ischemia times and were further enhanced in allogenic compared to isogenic kidney transplants. Taken together, these findings indicate that IRI is associated with increased systemic levels of CXCL13 in renal IRI and ktx.

Recent Advances on Biomarkers of Early and Late Kidney Graft Dysfunction

New biomarkers of early and late graft dysfunction are needed in renal transplant to improve management of complications and prolong graft survival. A wide range of potential diagnostic and prognostic biomarkers, measured in different biological fluids (serum, plasma, urine) and in renal tissues, have been proposed for post-transplant delayed graft function (DGF), acute rejection (AR), and chronic allograft dysfunction (CAD). This review investigates old and new potential biomarkers for each of these clinical domains, seeking to underline their limits and strengths. OMICs technology has allowed identifying many candidate biomarkers, providing diagnostic and prognostic information at very early stages of pathological processes, such as AR. Donor-derived cell-free DNA (ddcfDNA) and extracellular vesicles (EVs) are further promising tools. Although most of these biomarkers still need to be validated in multiple independent cohorts and standardized, they are paving the way for substantial advances, such as the possibility of accurately predicting risk of DGF before graft is implanted, of making a “molecular” diagnosis of subclinical rejection even before histological lesions develop, or of dissecting etiology of CAD. Identification of “immunoquiescent” or even tolerant patients to guide minimization of immunosuppressive therapy is another area of active research. The parallel progress in imaging techniques, bioinformatics, and artificial intelligence (AI) is helping to fully exploit the wealth of information provided by biomarkers, leading to improved disease nosology of old entities such as transplant glomerulopathy. Prospective studies are needed to assess whether introduction of these new sets of biomarkers into clinical practice could actually reduce the need for renal biopsy, integrate traditional tools, and ultimately improve graft survival compared to current management.

Kidney Inflammation, Injury and Regeneration

Damage to kidney cells can occur due to a variety of ischemic and toxic insults and leads to inflammation and cell death, which can result in acute kidney injury (AKI) [...].

Graph-based description of tertiary lymphoid organs at single-cell level

Our aim is to complement observer-dependent approaches of immune cell evaluation in microscopy images with reproducible measures for spatial composition of lymphocytic infiltrates. Analyzing such patterns of inflammation is becoming increasingly important for therapeutic decisions, for example in transplantation medicine or cancer immunology. We developed a graph-based assessment of lymphocyte clustering in full whole slide images. Based on cell coordinates detected in the full image, a Delaunay triangulation and distance criteria are used to build neighborhood graphs. The composition of nodes and edges are used for classification, e.g. using a support vector machine. We describe the variability of these infiltrates on CD3/CD20 duplex staining in renal biopsies of long-term functioning allografts, in breast cancer cases, and in lung tissue of cystic fibrosis patients. The assessment includes automated cell detection, identification of regions of interest, and classification of lymphocytic clusters according to their degree of organization. We propose a neighborhood feature which considers the occurrence of edges with a certain type in the graph to distinguish between phenotypically different immune infiltrates. Our work addresses a medical need and provides a scalable framework that can be easily adjusted to the requirements of different research questions.