CXCR3 and CCR5 positive T-cell recruitment in acute human renal allograft rejection

CD4+CD25+ T regulatory cells in renal transplantation

The immune response to an allograft activates lymphocytes with the capacity to cause rejection. Activation of CD4+CD25+Foxp3+T regulatory cells (Treg) can down-regulate allograft rejection and can induce immune tolerance to the allograft. Treg represent <10% of peripheral CD4+T cells and do not markedly increase in tolerant hosts. CD4+CD25+Foxp3+T cells include both resting and activated Treg that can be distinguished by several markers, many of which are also expressed by effector T cells. More detailed characterization of Treg to identify increased activated antigen-specific Treg may allow reduction of non-specific immunosuppression. Natural thymus derived resting Treg (tTreg) are CD4+CD25+Foxp3+T cells and only partially inhibit alloantigen presenting cell activation of effector cells. Cytokines produced by activated effector cells activate these tTreg to more potent alloantigen-activated Treg that may promote a state of operational tolerance. Activated Treg can be distinguished by several molecules they are induced to express, or whose expression they have suppressed. These include CD45RA/RO, cytokine receptors, chemokine receptors that alter pathways of migration and transcription factors, cytokines and suppression mediating molecules. As the total Treg population does not increase in operational tolerance, it is the activated Treg which may be the most informative to monitor. Here we review the methods used to monitor peripheral Treg, the effect of immunosuppressive regimens on Treg, and correlations with clinical outcomes such as graft survival and rejection. Experimental therapies involving ex vivo Treg expansion and administration in renal transplantation are not reviewed.

Chronic Inflammatory Placental Disorders Associated With Recurrent Adverse Pregnancy Outcome

Chronic inflammatory placental disorders are a group of rare but devastating gestational syndromes associated with adverse pregnancy outcome. This review focuses on three related conditions: villitis of unknown etiology (VUE), chronic histiocytic intervillositis (CHI) and massive perivillous fibrin deposition (MPFD). The hallmark of these disorders is infiltration of the placental architecture by maternal immune cells and disruption of the intervillous space, where gas exchange between the mother and fetus occurs. Currently, they can only be detected through histopathological examination of the placenta after a pregnancy has ended. All three are associated with a significant risk of recurrence in subsequent pregnancies. Villitis of unknown etiology is characterised by a destructive infiltrate of maternal CD8+ T lymphocytes invading into the chorionic villi, combined with activation of fetal villous macrophages. The diagnosis can only be made when an infectious aetiology has been excluded. VUE becomes more common as pregnancy progresses and is frequently seen with normal pregnancy outcome. However, severe early-onset villitis is usually associated with fetal growth restriction and recurrent pregnancy loss. Chronic histiocytic intervillositis is characterised by excessive accumulation of maternal CD68+ histiocytes in the intervillous space. It is associated with a wide spectrum of adverse pregnancy outcomes including high rates of first-trimester miscarriage, severe fetal growth restriction and late intrauterine fetal death. Intervillous histiocytes can also accumulate due to infection, including SARS-CoV-2, although this infection-induced intervillositis does not appear to recur. As with VUE, the diagnosis of CHI requires exclusion of an infectious cause. Women with recurrent CHI and their families are predisposed to autoimmune diseases, suggesting CHI may have an alloimmune pathology. This observation has driven attempts to prevent CHI with a wide range of maternal immunosuppression. Massive perivillous fibrin deposition is diagnosed when >25% of the intervillous space is occupied by fibrin, and is associated with fetal growth restriction and late intrauterine fetal death. Although not an inflammatory disorder per se, MPFD is frequently seen in association with both VUE and CHI. This review summarises current understanding of the prevalence, diagnostic features, clinical consequences, immune pathology and potential prophylaxis against recurrence in these three chronic inflammatory placental syndromes.

A study of the mechanisms responsible for the action of new immunosuppressants and their effects on rat small intestinal transplantation

In a series of studies, using an identical rat intestinal transplantation model, we evaluated the effects of several drugs. FK-506 caused a significant attenuation in the proliferation of allogeneic CD4+ T cells and IFN-γ secreting effector functions. FYT720 resulted in a marked reduction in the numbers of lymphocytes, associated with a reduction of T cell recruitment, in grafts. An anti-MAdCAM antibody was next reported to significantly down-regulate CD4+ T cell infiltration in intestinal grafts by blocking the adhesion molecule, and could be useful as an induction therapy. Concerning TAK-779, this CCR5 and CXCR3 antagonist diminished the number of graft-infiltrating cells by suppressing the expression of their receptors in the graft. As a result, it reduced the total number of recipient T cells involved in graft rejection. As the next step, we focused on the participation of monocytes/ macrophages in this field. PQA-18 has been the focus of a novel immunosuppressant that attenuates not only the production of various cytokines, such as IL-2 & TNF-α, on T cells, but the differentiation of macrophages by inhibiting PAK2 as well. In this report, we summarize our previous studies not only regarding the above drugs, but on an anti-complement drug and a JAK inhibitor as well.

A Combined microRNA and Chemokine Profile in Urine to Identify Rejection After Kidney Transplantation

Supplemental Digital Content is available in the text.

There is an unmet need for noninvasive tools for diagnosis of rejection after kidney transplantation. The aim of this study was to determine the discriminative value of a combined cellular and molecular biomarker platform in urine for the detection of rejection.

T helper cell trafficking in autoimmune kidney diseases

CD4⁺ T cells are key drivers of autoimmune diseases, including crescentic GN. Many effector mechanisms employed by T cells to mediate renal damage and repair, such as local cytokine production, depend on their presence at the site of inflammation. Therefore, the mechanisms regulating the renal CD4⁺ T cell infiltrate are of central importance. From a conceptual point of view, there are four distinct factors that can regulate the abundance of T cells in the kidney: (1) T cell infiltration, (2) T cell proliferation, (3) T cell death and (4) T cell retention/egress. While a substantial amount of data on the recruitment of T cells to the kidneys in crescentic GN have accumulated over the last decade, the roles of T cell proliferation and death in the kidney in crescentic GN is less well characterized. However, the findings from the data available so far do not indicate a major role of these processes. More importantly, the molecular mechanisms underlying both egress and retention of T cells from/in peripheral tissues, such as the kidney, are unknown. Here, we review the current knowledge of mechanisms and functions of T cell migration in renal autoimmune diseases with a special focus on chemokines and their receptors.

Inactivation of the PD-1-Dependent Immunoregulation in Mice Exacerbates Contact Hypersensitivity Resembling Immune-Related Adverse Events

Blockade of PD-1, an indispensable physiological immunoregulatory mechanism, enhances immune activities and is widely used in the immunotherapy of cancer. This treatment often accompanies inflammatory complication called immune-related adverse events (irAE), most frequently in the skin. To analyze how skin inflammation develops by the blockade of PD-1-dependent immunoregulation, we studied the exacerbation of oxazolone-induced contact hypersensitivity by PD-L1 blockade. The inactivation of PD-1 signaling enhanced swelling of the skin with massive CD8⁺ T cell infiltration. Among PD-1-expressing cells, T cells were the predominant targets of anti-PD-L1 mAb treatment since PD-L1 blockade did not affect skin inflammation in RAG2^-/- mice. PD-L1 blockade during immunization with oxazolone significantly promoted the development of hapten-reactive T cells in the draining lymph nodes. The enhancement of local CD8⁺ T cell-dominant immune responses by PD-L1 blockade was correlated with the upregulation of CXCL9 and CXCL10. Challenges with a low dose of oxazolone did not demonstrate any significant dermatitis; however, the influence of PD-L1 blockade on T cell immunity was strong enough to cause the emergence of notable dermatitis in this suboptimal dosing, suggesting its relevance to dermal irAE development. In the low-dose setting, the blockade of CXCR3, receptor of CXCL9/10, prevented the induction of T cell-dominant inflammation by anti-PD-L1 mAb. This experimental approach reproduced CD8⁺ T cell-dominant form of cutaneous inflammation by the blockade of PD-L1 that has been observed in dermal irAE in human patients.

Single cell transcriptomics of mouse kidney transplants reveals a myeloid cell pathway for transplant rejection

Myeloid cells are increasingly recognized as major players in transplant rejection. Here, we used a murine kidney transplantation model and single cell transcriptomics to dissect the contribution of myeloid cell subsets and their potential signaling pathways to kidney transplant rejection. Using a variety of bioinformatic techniques, including machine learning, we demonstrate that kidney allograft–infiltrating myeloid cells followed a trajectory of differentiation from monocytes to proinflammatory macrophages, and they exhibited distinct interactions with kidney allograft parenchymal cells. While this process correlated with a unique pattern of myeloid cell transcripts, a top gene identified was Axl, a member of the receptor tyrosine kinase family Tyro3/Axl/Mertk (TAM). Using kidney transplant recipients with Axl gene deficiency, we further demonstrate that Axl augmented intragraft differentiation of proinflammatory macrophages, likely via its effect on the transcription factor Cebpb. This, in turn, promoted intragraft recruitment, differentiation, and proliferation of donor-specific T cells, and it enhanced early allograft inflammation evidenced by histology. We conclude that myeloid cell Axl expression identified by single cell transcriptomics of kidney allografts in our study plays a major role in promoting intragraft myeloid cell and T cell differentiation, and it presents a potentially novel therapeutic target for controlling kidney allograft rejection and improving kidney allograft survival.

In a murine model of allogeneic kidney transplantation, single-cell transcriptomics identifies that myeloid cell Axl expression promotes allograft rejection by inducing inflammatory macrophage differentiation.

Diagnostic yield of 18 F-FDG PET/CT imaging and urinary CXCL9/creatinine levels in kidney allograft subclinical rejection

Subclinical kidney allograft acute rejection (SCR) corresponds to "the unexpected histological evidence of acute rejection in a stable patient." SCR detection relies on surveillance biopsy. Noninvasive approaches may help avoid biopsy-associated complications. From November 2015 to January 2018, we prospectively performed positron emission tomography/computed tomography (PET/CT) after injection of F¹⁸ -fluorodeoxyglucose (¹⁸ F-FDG) in adult kidney transplant recipients with surveillance biopsy at ~3 months posttransplantation. The Banff-2017 classification was used. The ratio of the mean standard uptake value (mSUVR) between kidney cortex and psoas muscle was measured. Urinary levels of CXCL-9 were concomitantly quantified. Our 92-patient cohort was categorized upon histology: normal (n = 70), borderline (n = 16), and SCR (n = 6). No clinical or biological difference was observed between groups. The mSUVR reached 1.87 ± 0.55, 1.94 ± 0.35, and 2.41 ± 0.54 in normal, borderline, and SCR groups, respectively. A significant difference in mSUVR was found among groups. Furthermore, mSUVR was significantly higher in the SCR vs normal group. The area under the receiver operating characteristic curve (AUC) was 0.79, with 83% sensitivity using an mSUVR threshold of 2.4. The AUC of urinary CXCL-9/creatinine ratios comparatively reached 0.79. The mSUVR positively correlated with ti and acute composite Banff scores. ¹⁸ F-FDG-PET/CT helps noninvasively exclude SCR, with a negative predictive value of 98%. External validations are required.

Identification of potential key protein interaction networks of BK virus nephropathy in patients receiving kidney transplantation

We aim to identify the key protein interaction networks and implicated pathways of BK virus nephropathy (BKVN) via bioinformatic methods. The microarray data GSE75693 of 30 patients with stable kidney transplantation and 15 with BKVN were downloaded and analyzed by using the limma package to identify differentially expressed genes (DEGs). Then the gene ontology (GO) functional enrichment analysis and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were done to investigate the molecular function (MF), biological process (BP), cellular components (CC) and pathways of DEGs. Finally, protein-protein interactions (PPIs) were constructed, and the hub proteins were  identified. As a result, 249 up-regulated genes and 253 down-regulated genes of BKVN patients were selected based on criteria of P > 0.01 and fold change >2.0. GO and KEGG showed that DEGs were mainly located in nucleus and cytosol, and were implicated in the immune responses. In the PPI analysis, 26 up-regulated and 8 down-regulated proteins composed the pivotal interaction network. CXCL10, EGF and STAT1 were identified as hub proteins in BKVN. In conclusion, CXCL10, EGF and STAT1 may induce kidney injuries by promoting inflammation and prohibiting reparation of tissue damage in BKVN.

Chronic inflammatory lesions of the placenta are associated with an up-regulation of amniotic fluid CXCR3: A marker of allograft rejection

OBJECTIVE

The objective of this study is to determine whether the amniotic fluid (AF) concentration of soluble CXCR3 and its ligands CXCL9 and CXCL10 changes in patients whose placentas show evidence of chronic chorioamnionitis or other placental lesions consistent with maternal anti-fetal rejection.

METHODS

This retrospective case-control study included 425 women with (1) preterm delivery (n=92); (2) term in labor (n=68); and (3) term not in labor (n=265). Amniotic fluid CXCR3, CXCL9 and CXCL10 concentrations were determined by ELISA.

RESULTS

(1) Amniotic fluid concentrations of CXCR3 and its ligands CXCL9 and CXCL10 are higher in patients with preterm labor and maternal anti-fetal rejection lesions than in those without these lesions [CXCR3: preterm labor and delivery with maternal anti-fetal rejection placental lesions (median, 17.24 ng/mL; IQR, 6.79-26.68) vs. preterm labor and delivery without these placental lesions (median 8.79 ng/mL; IQR, 4.98-14.7; P=0.028)]; (2) patients with preterm labor and chronic chorioamnionitis had higher AF concentrations of CXCL9 and CXCL10, but not CXCR3, than those without this lesion [CXCR3: preterm labor with chronic chorioamnionitis (median, 17.02 ng/mL; IQR, 5.57-26.68) vs. preterm labor without chronic chorioamnionitis (median, 10.37 ng/mL; IQR 5.01-17.81; P=0.283)]; (3) patients with preterm labor had a significantly higher AF concentration of CXCR3 than those in labor at term regardless of the presence or absence of placental lesions.

CONCLUSION

Our findings support a role for maternal anti-fetal rejection in a subset of patients with preterm labor.

CXCL10 and IL-6: Markers of two different forms of intra-amniotic inflammation in preterm labor

Problem

To determine whether amniotic fluid (AF) CXCL10 concentration is associated with histologic chronic chorioamnionitis in patients with preterm labor (PTL) and preterm prelabor rupture of the membranes (PROM).

Method of Study

This study included 168 women who had an episode of PTL or preterm PROM. AF interleukin (IL)‐6 and CXCL10 concentrations were determined by immunoassay.

Results

(i) Increased AF CXCL10 concentration was associated with chronic (OR: 4.8; 95% CI: 1.7‐14), but not acute chorioamnionitis; (ii) increased AF IL‐6 concentration was associated with acute (OR: 4.2; 95% CI: 1.3‐13.7) but not chronic chorioamnionitis; and (iii) an increase in AF CXCL10 concentration was associated with placental lesions consistent with maternal anti‐fetal rejection (OR: 3.7; 95% CI: 1.3‐10.4). (iv) All patients with elevated AF CXCL10 and IL‐6 delivered preterm.

Conclusion

Increased AF CXCL10 concentration is associated with chronic chorioamnionitis or maternal anti‐fetal rejection, whereas increased AF IL‐6 concentration is associated with acute histologic chorioamnionitis.

Salt suppresses IFNγ inducible chemokines through the IFNγ-JAK1-STAT1 signaling pathway in proximal tubular cells

The mechanisms of immunoactivation by salt are now becoming clearer. However, those of immunosuppression remain unknown. Since clinical evidence indicates that salt protects proximal tubules from injury, we investigated mechanisms responsible for salt causing immunosuppression in proximal tubules. We focused on cytokine-related gene expression profiles in kidneys of mice fed a high salt diet using microarray analysis and found that both an interferon gamma (IFNγ) inducible chemokine, chemokine (C-X-C motif) ligand 9 (CXCL9), and receptor, CXCR3, were suppressed. We further revealed that a high salt concentration suppressed IFNγ inducible chemokines in HK2 proximal tubular cells. Finally, we demonstrated that a high salt concentration decreased IFNGR1 expression in the basolateral membrane of HK2 cells, leading to decreased phosphorylation of activation sites of Janus kinase 1 (JAK1) and Signal Transducers and Activator of Transcription 1 (STAT1), activators of chemokines. JAK inhibitor canceled the effect of a high salt concentration on STAT1 and chemokines, indicating that the JAK1-STAT1 signaling pathway is essential for this mechanism. In conclusion, a high salt concentration suppresses IFNγ-JAK1-STAT1 signaling pathways and chemokine expressions in proximal tubules. This finding may explain how salt ameliorates proximal tubular injury and offer a new insight into the linkage between salt and immunity.

Infiltrating T cells promote renal cell carcinoma (RCC) progression via altering the estrogen receptor β-DAB2IP signals

Previous studies indicated the T cells, one of the most common types of immune cells existing in the microenvironment of renal cell carcinoma (RCC), may influence the progression of RCC. The potential linkage of T cells and the estrogen receptor beta (ERβ), a key player to impact RCC progression, however, remains unclear. Our results demonstrate that RCC cells can recruit more T cells than non-malignant kidney cells. Using an in vitro matrigel invasion system, we found infiltrating T cells could promote RCC cells invasion via increasing ERβ expression and transcriptional activity. Mechanism dissection suggested that co-culturing T cells with RCC cells released more T cell attraction factors, including IFN-γ, CCL3 and CCL5, suggesting a positive regulatory feed-back mechanism. Meanwhile, infiltrating T cells may also promote RCC cell invasion via increased ERβ and decreased DAB2IP expressions, and knocking down DAB2IP can then reverse the T cells-promoted RCC cell invasion. Together, our results suggest that infiltrating T cells may promote RCC cell invasion via increasing the RCC cell ERβ expression to inhibit the tumor suppressor DAB2IP signals. Further mechanism dissection showed that co-culturing T cells with RCC cells could produce more IGF-1 and FGF-7, which may enhance the ERβ transcriptional activity. The newly identified relationship between infiltrating T cells/ERβ/DAB2IP signals may provide a novel therapeutic target in the development of agents against RCC.

Microfluidic mazes to characterize T-cell exploration patterns following activation in vitro

The migration of T-cell subsets within peripheral tissues is characteristic of inflammation and immunoregulation. In general, the lymphocyte migratory response is assumed directional and guided by local gradients of chemoattractants and/or chemorepellents. However, little is known about how cells explore their tissue environment, and whether lymphocyte activation may influence speed and exploratory patterns of migration. To probe migration patterns by T-cells we designed a microfluidic maze device that replicates critical features of a tissue-like microenvironment. We quantified the migration patterns of unstimulated and mitogen-activated human T-cells at single cell resolution and found significant differences in exploration within microfluidic mazes. While unstimulated lymphocytes migrated in a directed manner, activated T-cells migrated through large areas of the mazes in an exploratory pattern in response to the chemoattractants RANTES (CCL5) and IP-10 (CXCL10). The analysis of migration enabled by the microfluidic devices help develop new methods for determining how human circulating T-cells function in vivo to seek out antigens in health and disease states.

Non-invasive approaches in the diagnosis of acute rejection in kidney transplant recipients, part II: omics analyses of urine and blood samples

Kidney transplantation (KTx) represents the best available treatment for patients with end-stage renal disease. Still, the full benefits of KTx are undermined by acute rejection (AR). The diagnosis of AR ultimately relies on transplant needle biopsy. However, such an invasive procedure is associated with a significant risk of complications and is limited by sampling error and interobserver variability. In the present review, we summarize the current literature about non-invasive approaches for the diagnosis of AR in kidney transplant recipients (KTRs), including in vivo imaging, gene-expression profiling and omics analyses of blood and urine samples. Most imaging techniques, such as contrast-enhanced ultrasound and magnetic resonance, exploit the fact that blood flow is significantly lowered in case of AR-induced inflammation. In addition, AR-associated recruitment of activated leucocytes may be detectable by 18F-fluorodeoxyglucose positron emission tomography. In parallel, urine biomarkers, including CXCL9/CXCL10 or a three-gene signature of CD3ε, CXCL10 and 18S RNA levels, have been identified. None of these approaches has yet been adopted in the clinical follow-up of KTRs, but standardization of analysis procedures may help assess reproducibility and comparative diagnostic yield in large, prospective, multicentre trials.

Netrin-1 Augments Chemokinesis in CD4+ T Cells In Vitro and Elicits a Proinflammatory Response In Vivo

Netrin-1 is a neuronal guidance cue that regulates cellular activation, migration, and cytoskeleton rearrangement in multiple cell types. It is a chemotropic protein that is expressed within tissues and elicits both attractive and repulsive migratory responses. Netrin-1 has recently been found to modulate the immune response via the inhibition of neutrophil and macrophage migration. However, the ability of Netrin-1 to interact with lymphocytes and its in-depth effects on leukocyte migration are poorly understood. In this study, we profiled the mRNA and protein expression of known Netrin-1 receptors on human CD4(+) T cells. Neogenin, uncoordinated-5 (UNC5)A, and UNC5B were expressed at low levels in unstimulated cells, but they increased following mitogen-dependent activation. By immunofluorescence, we observed a cytoplasmic staining pattern of neogenin and UNC5A/B that also increased following activation. Using a novel microfluidic assay, we found that Netrin-1 stimulated bidirectional migration and enhanced the size of migratory subpopulations of mitogen-activated CD4(+) T cells, but it had no demonstrable effects on the migration of purified CD4(+)CD25(+)CD127(dim) T regulatory cells. Furthermore, using a short hairpin RNA knockdown approach, we observed that the promigratory effects of Netrin-1 on T effectors is dependent on its interactions with neogenin. In the humanized SCID mouse, local injection of Netrin-1 into skin enhanced inflammation and the number of neogenin-expressing CD3(+) T cell infiltrates. Neogenin was also observed on CD3(+) T cell infiltrates within human cardiac allograft biopsies with evidence of rejection. Collectively, our findings demonstrate that Netrin-1/neogenin interactions augment CD4(+) T cell chemokinesis and promote cellular infiltration in association with acute inflammation in vivo.

Serum levels of CXCR3 ligands predict T cell-mediated acute rejection after kidney transplantation

The early diagnosis of acute rejection is crucial for graft survival after kidney transplantation. The interferon-γ (IFNγ)-CXCR3-chemokine-dependent inflammatory loop plays a pivotal role in the recruitment of T lymphocytes during acute rejection. Previously published studies have typically focused on the CXCR3 receptor rather than on its ligands. In the present study, we used Luminex assays to detect the levels of CXCR3 ligands, monokine induced by IFNγ (MIG), IFN-induced protein 10 (IP-10) and IFN-induced T‑cell chemoattractant (I-TAC), in the serum of renal allograft recipients. According to a renal biopsy performed one month after kidney transplantation, 32 recipients were diagnosed with T cell-mediated acute rejection and 38 patients were evaluated as stable. Serum was collected after the diagnosis of acute rejection or one month after transplantation. The concentrations of MIG (median, 4,271 pg/ml), IP-10 (median, 686.7 pg/ml) and I-TAC (median, 44.32 pg/ml) in the serum during an acute rejection episode were significantly higher compared with those of the stable patients (MIG, P=0.0002; IP-10, P=0.0001; I-TAC, P=0.0103; vs. the stable function group, P<0.05). Based on the receiver-operating characteristic (ROC) curve, the joint detection of MIG, IP-10 and I-TAC in the serum using Luminex analysis may constitute a non-invasive and efficient method for the early prediction of T cell-mediated acute rejection following kidney transplantation.

Multicenter validation of urinary CXCL9 as a risk-stratifying biomarker for kidney transplant injury

Noninvasive biomarkers are needed to assess immune risk and ultimately guide therapeutic decision-making following kidney transplantation. A requisite step toward these goals is validation of markers that diagnose and/or predict relevant transplant endpoints. The Clinical Trials in Organ Transplantation-01 protocol is a multicenter observational study of biomarkers in 280 adult and pediatric first kidney transplant recipients. We compared and validated urinary mRNAs and proteins as biomarkers to diagnose biopsy-proven acute rejection (AR) and stratify patients into groups based on risk for developing AR or progressive renal dysfunction. Among markers tested for diagnosing AR, urinary CXCL9 mRNA (odds ratio [OR] 2.77, positive predictive value [PPV] 61.5%, negative predictive value [NPV] 83%) and CXCL9 protein (OR 3.40, PPV 67.6%, NPV 92%) were the most robust. Low urinary CXCL9 protein in 6-month posttransplant urines obtained from stable allograft recipients classified individuals least likely to develop future AR or a decrement in estimated glomerular filtration rate between 6 and 24 months (92.5-99.3% NPV). Our results support using urinary CXCL9 for clinical decision-making following kidney transplantation. In the context of acute dysfunction, low values can rule out infectious/immunological causes of injury. Absent urinary CXCL9 at 6 months posttransplant defines a subgroup at low risk for incipient immune injury.

Maternal floor infarction/massive perivillous fibrin deposition: a manifestation of maternal antifetal rejection?

OBJECTIVE

Massive perivillous fibrin deposition (MPFD) and maternal floor infarction (MFI) are related placental lesions often associated with fetal death and fetal growth restriction. A tendency to recur in subsequent pregnancies has been reported. This study was conducted to determine whether this complication of pregnancy could reflect maternal antifetal rejection.

METHODS

Pregnancies with MPFD were identified (n = 10). Controls consisted of women with uncomplicated pregnancies who delivered at term without MPFD (n = 175). Second-trimester maternal plasma was analyzed for panel-reactive anti-HLA class I and class II antibodies. The prevalence of chronic chorioamnionitis, villitis of unknown etiology, and plasma cell deciduitis was compared between cases and controls. Immunohistochemistry was performed on available umbilical vein segments from cases with MPFD (n = 4) to determine whether there was evidence of complement activation (C4d deposition). Specific maternal HLA-antibody and fetal HLA-antigen status were also determined in paired specimens (n = 6). Plasma CXCL-10 concentrations were measured in longitudinal samples of cases (n = 28 specimens) and controls (n = 749 specimens) by ELISA. Linear mixed-effects models were used to test for differences in plasma CXCL-10 concentration.

RESULTS

(i) The prevalence of plasma cell deciduitis in the placenta was significantly higher in cases with MPFD than in those with uncomplicated term deliveries (40% versus 8.6%, P = 0.01), (ii) patients with MPFD had a significantly higher frequency of maternal anti-HLA class I positivity during the second trimester than those with uncomplicated term deliveries (80% versus 36%, P = 0.01); (iii) strongly positive C4d deposition was observed on umbilical vein endothelium in cases of MPFD, (iv) a specific maternal antibody against fetal HLA antigen class I or II was identified in all cases of MPFD; and 5) the mean maternal plasma concentration of CXCL-10 was higher in patients with evidence of MPFD than in those without evidence of MFPD (P < 0.001).

CONCLUSION

A subset of patients with MPFD has evidence of maternal antifetal rejection.

Study of CC chemokine receptor 5 in renal allograft rejection

Allospecific recruitment of T cells is primary to the pathogenesis of renal transplant rejection. Chemokines and their receptors inducing a Th1 cytokine response play a central role in this recruitment. Renal allograft biopsies of 28 patients with acute cellular rejection and 10 protocol biopsies (controls) were examined in accordance with Banff grading 2007 schema. Immunohistochemistry for CD3 and CC chemokine receptor 5 (CCR5) in sequential sections was performed and quantitatively assessed in the glomeruli, tubules, and interstitium. Histopathologic and clinical correlations were carried out. CD3- and CCR5-positive cells were observed in significantly higher numbers in rejection cases than in controls (P = 0.010). A larger proportion of CCR5-positive cells were noted in the foci of tubulitis compared to the interstitial infiltrates and glomeruli in all cases, and it correlated with the grade of cellular rejection (P = 0.010). A greater number of CCR5-positive cells were seen in early rejection (<6 months posttransplant) compared to late rejection. No clinical correlation with serum creatinine levels was found. CCR5-positive cells represent the alloaggressive subset of T cells in ACR, and their numbers correlate with rejection severity. CCR5 may be used as a marker of early acute rejection and may be an important target for future antirejection therapies.

Differential effects of activated human renal epithelial cells on T-cell migration

BACKGROUND

Renal tubular epithelial cells (TECs) are one of the main targets of inflammatory insults during interstitial nephritis and kidney transplant rejection. While Th1 cells are know to be essential in the pathogenesis of rejection, the role of Th17 is still under debate. We hypothesize that TECs modulate the outcome of rejection process by production of distinct chemokines and cytokines that determine the attraction of different T-cell subsets. Therefore, we studied differential effects of activated human renal epithelial cells on T-cell migration.

METHODS

Human primary TECs were stimulated by IFN-γ and TNF-α in vitro. Chemokines and cytokines produced by activated TECs were measured using Luminex or ELISA. Chemotaxis assay was performed using activated peripheral blood mononuclear cells composed of CD4+CXCR3+ and CD4+CCR6+ T cells migrating towards stimulated and unstimulated TECs.

RESULTS

While activated TECs secreted abundant amounts of the pro-inflammatory cytokines IL-6 and IL-8, the T helper cell differentiation cytokines IL-1β, IL-12p70, IL-23 or TGF-β1 were not produced. The production of Th1 chemokines CXCL9, CXCL10 and CCL5 were significantly upregulated after TEC stimulation. In contrast, Th17 chemokine CCL20 could not be detected. Finally, activated TECs attracted significantly higher numbers of CD4+CXCR3+ T cells as compared to unstimulated TECs. No migration of CD4+CCR6+ T cells could be observed.

CONCLUSION

Activated primary renal tubular epithelial cells do not attract Th17 cells nor produce cytokines promoting Th17 cell differentiation in our experimental system mimicking the proinflammatory microenvironment of rejection.

CXCR3 deficiency prolongs Th1-type contact hypersensitivity

Sensitization and challenge using dinitrofluorobenzene (DNFB) induce contact hypersensitivity (CHS) with Th1 cell infiltration, whereas those using FITC generate CHS with Th2 cell infiltration. In this study, we attempted to determine the role of CXCR3, a chemokine receptor, in Th1- and Th2-type CHS induced by DNFB or FITC using CXCR3-deficient (CXCR3(-/-)) mice. Ear swelling was prolonged after DNFB challenge in CXCR3(-/-) mice, which was accompanied by increased Th1 cytokines and decreased TGF-β and IL-10 expression at a late time point of CHS, whereas there was no significant difference between wild-type and CXCR3(-/-) mice in FITC-induced CHS. In Th1-type CHS, the number of regulatory T cells (Tregs) was decreased in the challenged ear of CXCR3(-/-) mice compared with that of wild-type mice, suggesting that CXCR3 would be important in migration of Tregs into the site of inflammation. Moreover, we examined the characteristics of CXCR3(+) Tregs both in vitro and in vivo, revealing that CXCR3(+) Tregs expressed high levels of TGF-β and IL-10 as well as IFN-γ compared with CXCR3(-) Tregs. When CXCR3(-/-) mice were injected with CXCR3(+) Tregs, the prolonged ear swelling induced by DNFB was normalized. Taken together, our results suggest that CXCR3(+) Tregs play a key role for quenching Th1-type CHS.

Recruitment of Th1 effector cells in human tuberculosis: hierarchy of chemokine receptor(s) and their ligands

Selective recruitment of IFN-γ biased Th1 effector cells at the pathologic site(s) determines the local immunity of tuberculosis (TB). We observed the enrichment of CXCR3, CCR5 and CD11a(high) T cells in the peripheral blood, pleural fluid and bronchoalveolar lavage of TB pleural effusion (TB-PE) and miliary tuberculosis (MTB) patients respectively. CXCR3(+)CCR5(+) T cells were significantly high at the local disease site(s) in both the forms of TB and their frequency was highest among activated lymphocytes in TB-PE. Interestingly, all CCR5(+) cells were invariably positive for CXCR3 but all CXCR3(+) cells did not co-express CCR5 in pleural fluid whereas the situation was reverse in bronchoalveolar lavage. These CXCR3(+)CCR5(+) cells dominantly produced IFN-γ in response to Mycobacterium tuberculosis antigen. In vitro chemotaxis assay indicates dominant role of RANTES and IP-10 in the selective recruitment of CXCR3(+)CCR5(+)cells at the tubercular pathologic sites.

Interleukin-33 in the human placenta

OBJECTIVE

Interleukin-33 (IL-33) is the newest member of the IL-1 cytokine family, a group of key regulators of inflammation. The purpose of this study was to determine whether IL-33 is expressed in the human placenta and to investigate its expression in the context of acute and chronic chorioamnionitis.

METHODS

Placental tissues were obtained from five groups of patients: 1) normal pregnancy at term without labor (n = 10); 2) normal pregnancy at term in labor (n = 10); 3) preterm labor without inflammation (n = 10); 4) preterm labor with acute chorioamnionitis and funisitis (n = 10); and 5) preterm labor with chronic chorioamnionitis (n = 10). Immunostaining was performed to determine IL-33 protein expression patterns in the placental disk, chorioamniotic membranes, and umbilical cord. mRNA expression of IL-33 and its receptor IL1RL1 (ST2) was measured in primary amnion epithelial and mesenchymal cells (AECs and AMCs, n = 4) and human umbilical vein endothelial cells (HUVECs, n = 4) treated with IL-1β (1 and 10 ng/ml) and CXCL10 (0.5 and 1 or 5 ng/ml).

RESULTS

1) Nuclear IL-33 expression was found in endothelial and smooth muscle cells in the placenta, chorioamniotic membranes, and umbilical cord; 2) IL-33 was detected in the nucleus of CD14+ macrophages in the chorioamniotic membranes, chorionic plate, and umbilical cord, and in the cytoplasm of myofibroblasts in the Wharton's jelly; 3) acute (but not chronic) chorioamnionitis was associated with the presence of IL-33+ macrophages in the chorioamniotic membranes and umbilical cord; 4) expression of IL-33 or IL1RL1 (ST2) mRNA in AECs was undetectable; 5) IL-33 mRNA expression increased in AMCs and HUVECs after IL-1β treatment but did not change with CXCL10 treatment; and 6) IL1RL1 (ST2) expression decreased in AMCs and increased in HUVECs after IL-1β but not CXCL10 treatment.

CONCLUSIONS

IL-33 is expressed in the nucleus of placental endothelial cells, CD14+ macrophages, and myofibroblasts in the Wharton's jelly. IL-1β can induce the expression of IL-33 and its receptor. Protein expression of IL-33 is detectable in macrophages of the chorioamniotic membranes in acute (but not chronic) chorioamnionitis.

Peripherally circulating CD4⁺ FOXP3⁺ CXCR3⁺ T regulatory cells correlate with renal allograft function

Peripheral immunoregulation depends on T regulatory cell trafficking into the allograft to modulate the local alloresponse. Little is known about the relevance of trafficking receptors for Tregs after solid organ transplantation in humans. In this study, expression of the peripheral chemokine receptors CXCR3 and CCR5 on CD4⁺ FOXP3⁺ Treg cells was analysed and correlated with allograft function in renal transplant recipients. Flow cytometry analysis of peripheral blood mononuclear cells of 54 renal transplant recipients receiving a calcineurin inhibitor-based immunosuppression was performed for CD4, CD25, FOXP3, CXCR3 and CCR5 within the first 18 months post-transplantation. Correlation analysis of chemokine receptor expression and glomerular filtration rate as calculated by MDRD (eGFR) was performed. Expression of the peripheral homing receptors CXCR3 (r = 0.44, P < 0.05) and CCR5 (r = 0.45, P < 0.05) on FOXP3⁺ Tregs correlated with renal allograft function (eGFR) in patients receiving tacrolimus (n = 28), but not cyclosporine A (CsA) (n = 26). CsA but not tacrolimus reduced surface expression of CXCR3 on FOXP3⁺ Tregs in renal transplant recipients as correlated to trough levels (r = -0.42, P < 0.05). In contrast to CD4⁺ CXCR3⁺ CD25(lo) T cells, flow-sorted CD4⁺ CXCR3⁺ CD25(hi) Tregs isolated from healthy individuals did not produce IFNγ or IL-17 ex vivo and expressed high levels of GARP mRNA both at baseline as well as after TCR activation indicating functional regulatory activity. Expression of the peripheral trafficking receptors CXCR3 and CCR5 on FOXP3⁺ Tregs is associated with renal allograft function. These results suggest that Treg trafficking may also depend on the interaction of CXCR3 or CCR5 and their respective ligands.

Cyclosporin but not everolimus inhibits chemokine receptor expression on CD4+ T cell subsets circulating in the peripheral blood of renal transplant recipients

The peripheral chemokine receptors chemokine receptor 3 (CXCR3) and CC chemokine receptor 5 (CCR5) have been reported to be associated with allograft rejection. The impact of the expression of immunosuppressive drugs on peripherally circulating CD4(+) T cell subsets after renal transplantation is unknown. Expression of CXCR3 and CCR5 was investigated by flow cytometry in 20 renal allograft recipients participating in a prospective, randomized trial (NCT00514514). Initial immunosuppression consisted of basiliximab, cyclosporin A (CsA), mycophenolate sodium and corticosteroids. After 3 months, patients were treated either with CsA, mycophenolate sodium (MPA) plus corticosteroids (n = 6), CsA and everolimus plus corticosteroids (n =8) or CsA-free (CsA(free)) receiving everolimus, MPA and corticosteroids (n = 6). After initial reduction of CD4(+) forkhead box protein 3 (FoxP3)(+) and CD4(+) CD25(hi) FoxP3(+) regulatory T cells (T(regs)) (P < 0.05; P < 0.01), 3-month post-transplant percentages of T(regs) were reconstituted in CsA(free) and CsA(lo) arms compared to CsA(reg) 12 months post transplant. Expression of CCR5 and CXCR3 on CD4(+) FoxP3(+) and CD4(+) FoxP3(-) T cells 12 months post transplant was increased in CsA(free) versus CsA(reg). Increase in CCR5(+) CXCR3(+) co-expressing CD4(+) FoxP3(-) cells between 3 and 12 months correlated negatively with the glomerular filtration rate (GFR) slope/year [modification of diet in renal disease (MDRD); r = -0.59, P < 0.01]. CsA, but not everolimus, inhibits both T(reg) development and expression of CXCR3 and CCR5 on CD4(+) T cell subsets. Increase in CCR5(+) CXCR3(+) co-expressing CD4(+) FoxP3(-) T cells is associated with early loss in allograft function.

Characteristics of alloreactive T cells measured before renal transplantation

Several assays to measure pre-existing allospecific T cell immunity in renal transplant candidates have been developed in the past years. In 46 patients, we used flow cytometry-based mixed lymphocyte culture to measure the precursor frequency and phenotype of alloreactive T cells before renal transplantation, using donor-specific or third-party cells for allostimulation. Allostimulation induced up-regulation of co-stimulatory molecules, chemokine receptors relevant for migration of T cells into the graft and effector proteins. Recipients prone for acute rejection had a higher precursor frequency of alloreactive CD8(+) T cells and a lower percentage of interleukin (IL)-7Rα expressing alloreactive CD8(+) T cells than non-rejectors. These data point to quantitative and qualitative differences between T cells of patients who will experience acute cellular rejection episodes from those who will not.

Midtrimester amniotic fluid concentrations of interleukin-6 and interferon-gamma-inducible protein-10: evidence for heterogeneity of intra-amniotic inflammation and associations with spontaneous early (<32 weeks) and late (>32 weeks) preterm delivery

INTRODUCTION

Intra-amniotic inflammation is traditionally defined as an elevation of amniotic fluid interleukin (IL)-6. Previous case control studies have suggested an association between an elevated midtrimester amniotic fluid IL-6 and preterm delivery, although such an association has been recently challenged. Intra-amniotic inflammation can also be defined by an elevation of the T-cell chemokine, Interferon-gamma-inducible protein (IP)-10. An elevation in amniotic fluid IP-10 has been associated with chronic chorioamnionitis, a lesion frequently found in late spontaneous preterm birth and fetal death. In contrast, an elevation in amniotic fluid IL-6 is typically associated with acute chorioamnionitis and funisitis. This study was conducted to examine the relationship between an elevation in amniotic fluid IL-6 in the midtrimester and preterm delivery at or before 32 weeks of gestation, and the amniotic fluid concentration of IP-10 and preterm delivery after 32 weeks of gestation.

MATERIALS AND METHODS

This cohort study included 847 consecutive women undergoing genetic midtrimester amniocentesis; in 796 cases, amniotic fluid and pregnancy outcome was available for study after exclusion of abnormal karyotype and/or fetal congenital anomalies. Spontaneous preterm delivery was defined as early (≤32 weeks) or late (after 32 completed weeks of pregnancy). The amniotic fluid and maternal blood concentrations of IL-6 and IP-10 were measured by specific immunoassays.

RESULTS

1) The prevalence of preterm delivery was 8.3% (66/796), while those of early and late spontaneous preterm delivery were 1.5% (n=12), and 4.5% (n=36), respectively; 2) patients who had a spontaneous preterm delivery after 32 weeks of gestation had a higher median amniotic fluid IP-10 concentration than those who delivered at term [median 713 pg/mL, inter-quartile range (IQR) 509-1427 pg/mL vs. median 589 pg/mL, IQR 402-953 pg/mL; P=0.006] and an elevation of amniotic fluid IP-10 concentration above 502 pg/mL (derived from an ROC curve) was associated with late spontaneous preterm delivery [odds ratio 3.9 (95% CI 1.6-9.9)]; 3) patients who had a spontaneous preterm delivery ≤32 weeks of gestation had a higher median amniotic fluid IL-6 concentration than those who delivered at term [median 2052 pg/mL, IQR 435-3015 pg/mL vs. median 414 pg/mL, IQR 209-930 pg/mL; P=0.006], and an elevated amniotic fluid IL-6 concentration above 1740 pg/mL (derived from an ROC curve) was associated with early spontaneous preterm delivery [odds ratio 9.5 (95% CI 2.9-31.1)]; 4) subclinical intra-amniotic inflammation, defined as an elevation of IL-6 (≥2.9 ng/mL) or IP-10 (≥2.2 ng/mL) concentration above the 95th percentile of patients who had uncomplicated term delivery (n=652 for IL-6 and n=633 for IP-10), was observed in 6.3% (50/796) and 5.8% (45/770) of cases, respectively. Although each type of inflammation is a risk factor for spontaneous preterm delivery, many patients had a term delivery without complication; 5) the amniotic fluid in the midtrimester did not contain microorganisms detectable with cultivation techniques.

CONCLUSIONS

INTRA-amniotic inflammation is heterogeneous. Some patients have elevated amniotic fluid concentrations of IL-6, and are at risk for spontaneous preterm delivery before 32 weeks of gestation, while others have an elevated IP-10 (a chemotactic T-cell chemokine) and such patients are at risk for spontaneous preterm delivery after 32 weeks of gestation. A fraction of patients have subclinical intra-amniotic inflammation and deliver at term. The clinical significance of this condition remains to be determined.

Kinetics of T-lymphocyte subsets and posttransplant opportunistic infections in heart and kidney transplant recipients

BACKGROUND

The potential use of T-lymphocyte measurements as infection risk markers after solid organ transplant has not been fully investigated. We analyzed the kinetics of T-lymphocyte subsets within the first 8 months posttransplant and their correlation with opportunistic infections (OIs) in solid organ transplant recipients.

METHODS

Serial measurement of CD4 and CD8 T cells was performed retrospectively in 48 heart transplant recipients (HTR) and 42 kidney transplant recipients (KTR). Generalized estimating equation models were used to analyze longitudinal data separately for HTR and KTR.

RESULTS

An initial CD4 T-cell drop (at months 1 and 2, in HTR and KTR, respectively) coincided with the peak of OIs. HTR with a low nadir CD4 T-cell count (≤ 200/μL) showed poor CD4 T-cell recovery (175 ± 277 cells/μL at baseline vs 242 ± 99 cells/μL at month 8) and their CD8 T cells increased from 153 ± 194 cells/μL at baseline to 601 ± 399 cells/μL at month 8. KTR with a low nadir CD4 T-cell count (≤ 200/μL) showed a modest CD4 T-cell recovery (138 ± 46 cells/μL at baseline vs. 440 ± 448 cells/μL at month 8), and their CD8 T cells increased from 90 ± 41 cells/μL at baseline to 450 ± 242 cells/μL at month 8. HTR developing OIs had lower CD4 (P<0.001) and CD8 T cells (P=0.001) than those without infections, whereas in KTR the risk for OIs seemed restricted to patients with low CD8 T cells. HTR with OIs had a low CD4/CD8 T-cell ratio, whereas KTR had a high CD4/CD8 T-cell ratio.

CONCLUSIONS

Determination of T-lymphocyte subsets is a simple and effective parameter to identify patients at risk of developing OIs.

Subsets of human CD4(+) regulatory T cells express the peripheral homing receptor CXCR3

Regulatory T cells (Tregs) migrate into peripheral sites of inflammation such as allografts undergoing rejection, where they serve to suppress the immune response. In this study, we find that ∼30-40% of human CD25(hi) FOXP3(+) CD4(+) Tregs express the peripheral CXC chemokine receptor 3 (CXCR3) and that this subset has potent immunoregulatory properties. Consistently, we observed that proliferative responses as well as IFN-γ production were significantly higher using CXCR3-depleted versus undepleted responders in the mixed lymphocyte reaction, as well as following mitogen-dependent activation of T cells. Using microfluidics, we also found that CXCR3 was functional on CXCR3(pos) Tregs, in as much as chemotaxis and directional persistence towards interferon-γ-inducible protein of 10 kDa (IP-10) was significantly greater for CXCR3(pos) than CXCR3(neg) Tregs. Following activation, CXCR3-expressing CD4(+) Tregs were maintained in vitro in cell culture in the presence of the mammalian target of rapamycin (mTOR) inhibitor rapamycin, and we detected higher numbers of circulating CXCR3(+) FOXP3(+) T cells in adult and pediatric recipients of renal transplants who were treated with mTOR-inhibitor immunosuppressive therapy. Collectively, these results demonstrate that the peripheral homing receptor CXCR3 is expressed on subset(s) of circulating human Tregs and suggest a role for CXCR3 in their recruitment into peripheral sites of inflammation.

Human cytomegalovirus IE1 protein elicits a type II interferon-like host cell response that depends on activated STAT1 but not interferon-γ

Human cytomegalovirus (hCMV) is a highly prevalent pathogen that, upon primary infection, establishes life-long persistence in all infected individuals. Acute hCMV infections cause a variety of diseases in humans with developmental or acquired immune deficits. In addition, persistent hCMV infection may contribute to various chronic disease conditions even in immunologically normal people. The pathogenesis of hCMV disease has been frequently linked to inflammatory host immune responses triggered by virus-infected cells. Moreover, hCMV infection activates numerous host genes many of which encode pro-inflammatory proteins. However, little is known about the relative contributions of individual viral gene products to these changes in cellular transcription. We systematically analyzed the effects of the hCMV 72-kDa immediate-early 1 (IE1) protein, a major transcriptional activator and antagonist of type I interferon (IFN) signaling, on the human transcriptome. Following expression under conditions closely mimicking the situation during productive infection, IE1 elicits a global type II IFN-like host cell response. This response is dominated by the selective up-regulation of immune stimulatory genes normally controlled by IFN-γ and includes the synthesis and secretion of pro-inflammatory chemokines. IE1-mediated induction of IFN-stimulated genes strictly depends on tyrosine-phosphorylated signal transducer and activator of transcription 1 (STAT1) and correlates with the nuclear accumulation and sequence-specific binding of STAT1 to IFN-γ-responsive promoters. However, neither synthesis nor secretion of IFN-γ or other IFNs seems to be required for the IE1-dependent effects on cellular gene expression. Our results demonstrate that a single hCMV protein can trigger a pro-inflammatory host transcriptional response via an unexpected STAT1-dependent but IFN-independent mechanism and identify IE1 as a candidate determinant of hCMV pathogenicity.

Chemokines and their receptors in human renal allotransplantation

BACKGROUND

Chemokines and their receptors play a critical role in leukocyte trafficking, and inhibition of select chemokines has been shown to attenuate kidney disease and allograft rejection in animal models. Therefore, we evaluated chemokine and chemokine receptor transcripts in human renal allograft biopsies, correlating transcript levels with clinical course and immunohistochemical analysis to relate chemokine expression to relevant clinical human disease phenotypes.

METHODS

Renal biopsies were grouped as postreperfusion (n=10), stable function (n=10), subclinical (n=10) or acute rejection (n=17), or calcineurin inhibitor nephrotoxicity (n=9) based on clinical presentation and histopathologic assessment. Using quantitative real-time polymerase chain reaction analysis, chemokine transcripts were assessed relative to transcript levels in preprocurement biopsies from live donor kidneys (n=15).

RESULTS

Transcripts from several inflammatory chemokines (CCL3, CCL5, CXCL9, CXCL10, and CXCL11) and chemokine receptors (CCR5, CCR7, and CXCR3) were significantly increased in allografts with subclinical and clinical acute rejection, indicating a strong polarization toward a T-helper 1 effector phenotype during rejection. These transcripts also distinguished acutely rejecting allografts from allografts with nonrejection causes of renal dysfunction. Biopsies from patients with stable function without histologic evidence of rejection had increased chemokine transcript levels that were qualitatively similar but quantitatively reduced compared with rejecting allografts.

CONCLUSIONS

This comprehensive evaluation of chemokines and their receptors in human renal transplantation defines associations between chemokine expression and clinical phenotypes, may have diagnostic utility, and highlights relevant pathways for therapeutic intervention.

CXCL10 and CXCL13 Expression were highly up-regulated in peripheral blood mononuclear cells in acute rejection and poor response to anti-rejection therapy

BACKGROUND

Acute rejection is still one of the main complications which enhances the cost and the risk to renal graft failure. Chemokines, interacting with respective receptors, can recruit leukocytes into grafts and mediate allograft rejection. In this study, we aimed to analyze gene expression of chemokines including CCL5/RANTES, CXCL10/IP-10, CXCL13/BCA-1, and receptors of CCR5, CXCR3, CXCR5 in peripheral blood mononuclear cells (PBMCs) during acute renal allograft rejection

METHODS

Gene expression of all these chemokines and receptors in PBMCs were analyzed by real-time PCR from 14 stable recipients, 32 biopsy-proven acute rejection (AR), and 5 acute tubular necrosis (ATN).

RESULTS

Gene expression of CCL5, CXCL10, CXCL13, and CCR5 were up-regulated both in AR and ATN group compared to stable recipients (fold change>2, P<0.05). Serum creatinine recovered to baseline level after anti-rejection therapy was defined as AR-sensitive and creatinine maintained above 200 μmol/L as AR-resistant. Expression of CXCL10 and CXCL13 were 5.98-, 2.94-, and 20.5, 10.8-fold change in AR-resistant and AR-sensitive compared to stable recipients, respectively. The expression of CXCL10 and CXCL13 was a twofold change in AR-resistant compared to AR-sensitive recipients (P<0.05). Five out of ten AR-resistant recipients lost graft function in the follow-up.

CONCLUSION

CXCL10 and CXCL13 expression were highly up-regulated in PBMCs in acute renal allograft rejection, especially in poor response to anti-rejection therapy and detrimental prognosis.

The frequency, clinical significance, and pathological features of chronic chorioamnionitis: a lesion associated with spontaneous preterm birth

Acute chorioamnionitis is a well-established lesion of the placenta in cases with intra-amniotic infection. In contrast, the clinicopathological significance of chronic chorioamnionitis is unclear. This study was conducted to determine the frequency and severity of chronic chorioamnionitis in normal pregnancy and in various pregnancy complications. Placentas from the following patient groups were studied: (1) term not in labor (n=100), (2) term in labor (n=100), (3) preterm labor (n=100), (4) preterm prelabor rupture of membranes (n=100), (5) preeclampsia at term (n=100), (6) preterm preeclampsia (n=100), and (7) small-for-gestational-age at term (n=100). Amniotic fluid CXCL10 concentration was measured in 64 patients. CXCL9, CXCL10, and CXCL11 mRNA expressions in the chorioamniotic membranes were assessed using real-time quantitative reverse transcription-PCR. The frequency of chronic chorioamnionitis in the preterm labor group and the preterm prelabor rupture of membranes group was 34 and 39%, respectively, which was higher than that of normal-term placentas (term not in labor, 19%; term in labor, 8%; P<0.05 each). The frequency of chronic chorioamnionitis in the preeclampsia at term group, preterm preeclampsia group, and small-for-gestational-age group was 23, 16, and 13%, respectively. Concomitant villitis of unknown etiology was found in 38 and 36% of preterm labor cases and preterm prelabor rupture of membranes cases with chronic chorioamnionitis, respectively. Interestingly, the median gestational age of preterm chronic chorioamnionitis cases was higher than that of acute chorioamnionitis cases (P<0.05). The median amniotic fluid CXCL10 concentration was higher in cases with chronic chorioamnionitis than in those without, in both the preterm labor group and preterm prelabor rupture of membranes group (P<0.05 and P<0.01, respectively). CXCL9, CXCL10, and CXCL11 mRNA expression in the chorioamniotic membranes was also higher in cases with chronic chorioamnionitis than in those without chronic chorioamnionitis (P<0.05). We propose that chronic chorioamnionitis defines a common placental pathological lesion among the preterm labor and preterm prelabor rupture of membranes groups, especially in cases of late preterm birth. Its association with villitis of unknown etiology and the chemokine profile in amniotic fluid suggests an immunological origin, akin to transplantation rejection and graft-versus-host disease in the chorioamniotic membranes.

The role of CCR5 in HCV infection

Efficient recruitment and activation of immuno-competent cells is crucial for an effective immune response to hepatitis C virus (HCV) infection. Chemokines and chemokine receptors have been shown to be critically involved in these processes.

The CCR5 chemokine receptor is expressed on several cells of the immune system and has been suggested to influence the susceptibility to HCV infection as well as natural course and progression of hepatitis C. However, these reports are still controversial.

This review will summarize and discuss the available data regarding the potential role of CCR5 and its ligands in hepatitis C.

The chemokine receptor CXCR7 is expressed on lymphatic endothelial cells during renal allograft rejection

CXCR7 is an atypical receptor for the chemokines CXCL11 and CXCL12, which were found to be involved in animal models of allograft injury. We studied the expression of CXCR7 and its ligands in human kidneys by first quantifying the mRNA in 53 renal allograft biopsies. Receptor and ligand mRNAs were expressed in renal allografts, with a significant induction of CXCL11 and CXCL12 in biopsies showing borderline lesions and acute rejection. Immunohistochemical analysis for CXCR7 was performed in a series of 64 indication and 24 protocol biopsies. The indication biopsies included 46 acute rejections, 6 with interstitial fibrosis and tubular atrophy, and 12 pretransplant biopsies as controls. In control biopsies, CXCR7 protein was found on smooth muscle and on endothelial cells of a small number of peritubular vessels. The number of CXCR7-positive vessels was increased in acute rejection and, using double immunofluorescence labeling, a subset of these CXCR7-positive endothelial cells were identified as lymphatic vessels. Both CXCR7-positive blood and lymphatic vessels increased during allograft rejection. We found that CXCR7 is present in both blood and lymphatic endothelial cells in human renal allografts. Whether its presence modulates the formation of chemokine gradients and the recruitment of inflammatory cells will require further experimental studies.

CXCR3 mediates renal Th1 and Th17 immune response in murine lupus nephritis

Infiltration of T cells into the kidney is a typical feature of human and experimental lupus nephritis that contributes to renal tissue injury. The chemokine receptor CXCR3 is highly expressed on Th1 cells and is supposed to be crucial for their trafficking into inflamed tissues. In this study, we explored the functional role of CXCR3 using the MRL/MpJ-Fas(lpr) (MRL/lpr) mouse model of systemic lupus erythematosus that closely resembles the human disease. CXCR3(-/-) mice were generated and backcrossed into the MRL/lpr background. Analysis of 20-wk-old CXCR3(-/-) MRL/lpr mice showed amelioration of nephritis with reduced glomerular tissue damage and decreased albuminuria and T cell recruitment. Most importantly, not only the numbers of renal IFN-gamma-producing Th1 cells, but also of IL-17-producing Th17 cells were significantly reduced. Unlike in inflamed kidneys, there was no reduction in the numbers of IFN-gamma- or IL-17-producing T cells in spleens, lymph nodes, or the small intestine of MRL/lpr CXCR3(-/-) mice. This observation suggests impaired trafficking of effector T cells to injured target organs, rather than the inability of CXCR3(-/-) mice to mount efficient Th1 and Th17 immune responses. These findings show a crucial role for CXCR3 in the development of experimental lupus nephritis by directing pathogenic effector T cells into the kidney. For the first time, we demonstrate a beneficial effect of CXCR3 deficiency through attenuation of both the Th1 and the newly defined Th17 immune response. Our data therefore identify the chemokine receptor CXCR3 as a promising therapeutic target in lupus nephritis.

Urinary CXCL9 and CXCL10 levels correlate with the extent of subclinical tubulitis

Subclinical tubulitis has been associated with the later development of interstitial fibrosis and tubular atrophy (IF/TA), leading to diminished allograft survival. The aim of this study was to investigate how concentrations of urinary CXC-receptor 3 (CXCR3) chemokines (i.e. CXCL4/9/10/11) and CCL2 relate to the extent of subclinical tubulitis. Using ELISA, urinary CXCR3 chemokines, CCL2 and tubular injury markers (i.e. urinary NGAL and alpha1-microglobulin [alpha1 m]) were measured in patients with stable estimated GFR >or=40 mL/min exhibiting normal tubular histology (n = 24), subclinical borderline tubulitis (n = 18) or subclinical tubulitis Ia/Ib (n = 22), as well as in patients with clinical tubulitis Ia/Ib (n = 17) or IF/TA (n = 10). CXCL9 and CXCL10 were significantly higher in subclinical tubulitis Ia/Ib than in subclinical borderline tubulitis (p <or= 0.03) and normal tubular histology (p <or= 0.0002). By contrast, NGAL, alpha1-m, CXCL4, CXCL11 and CCL2 were not or only marginally distinctive across these patient groups. All urinary chemokines and tubular injury markers were higher in clinical tubulitis Ia/Ib than in normal tubular histology (p <or= 0.002), but only tubular injury markers were elevated in IF/TA. These results demonstrate a correlation of urinary CXCL9 and CXCL10 levels with the extent of subclinical tubulitis suggesting potential as noninvasive screening biomarkers.

Villitis of unknown etiology is associated with a distinct pattern of chemokine up-regulation in the feto-maternal and placental compartments: implications for conjoint maternal allograft rejection and maternal anti-fetal graft-versus-host disease

The co-presence of histoincompatible fetal and maternal cells is a characteristic of human placental inflammation. Villitis of unknown etiology (VUE), a destructive inflammatory lesion of villous placenta, is characterized by participation of Hofbauer cells (placental macrophages) and maternal T cells. In contrast to acute chorioamnionitis of infection-related origin, the fundamental immunopathology of VUE is unknown. This study was performed to investigate the placental transcriptome of VUE and to determine whether VUE is associated with systemic maternal and/or fetal inflammatory response(s). Comparison of the transcriptome between term placentas without and with VUE revealed differential expression of 206 genes associated with pathways related to immune response. The mRNA expression of a subset of chemokines and their receptors (CXCL9, CXCL10, CXCL11, CXCL13, CCL4, CCL5, CXCR3, CCR5) was higher in VUE placentas than in normal placentas (p < 0.05). Analysis of blood cell mRNA showed a higher expression of CXCL9 and CXCL13 in the mother, and CXCL11 and CXCL13 in the fetus of VUE cases (p < 0.05). The median concentrations of CXCL9, CXCL10, and CXCL11 in maternal and fetal plasma were higher in VUE (p < 0.05). Comparison of preterm cases without and with acute chorioamnionitis revealed elevated CXCL9, CXCL10, CXCL11, and CXCL13 concentrations in fetal plasma (p < 0.05), but not in maternal plasma with chorioamnionitis. We report for the first time the placental transcriptome of VUE. A systemic derangement of CXC chemokines in maternal and fetal circulation distinguishes VUE from acute chorioamnionitis. We propose that VUE be a unique state combining maternal allograft rejection and maternal antifetal graft-vs-host disease mechanisms.

Endothelial cells in allograft rejection

In organ transplantation, blood borne cells and macromolecules (e.g., antibodies) of the host immune system are brought into direct contact with the endothelial cell lining of graft vessels. In this location, graft endothelial cells play several roles in allograft rejection, including the initiation of rejection responses by presentation of alloantigen to circulating T cells; the development of inflammation and thrombosis; and as targets of injury and agents of repair.

Endothelial cells in allograft rejection

In organ transplantation, blood borne cells and macromolecules (e.g., antibodies) of the host immune system are brought into direct contact with the endothelial cell lining of graft vessels. In this location, graft endothelial cells play several roles in allograft rejection, including the initiation of rejection responses by presentation of alloantigen to circulating T cells; the development of inflammation and thrombosis; and as targets of injury and agents of repair.

Differential regulation of chemokine CCL5 expression in monocytes/macrophages and renal cells by Y-box protein-1

The Y-box protein-1 (YB-1) belongs to the family of cold shock proteins that have pleiotropic functions such as gene transcription, RNA splicing, and mRNA translation. YB-1 has a critical role in atherogenesis due to its regulatory effects on chemokine CCL5 (RANTES) gene transcription in vascular smooth muscle cells. Since CCL5 is a key mediator of kidney transplant rejection, we determined whether YB-1 is involved in allograft rejection by manipulating its expression. In human kidney biopsies, YB-1 transcripts were amplified 17-fold in acute and 21-fold in chronic allograft rejection with a close correlation between CCL5 and YB-1 mRNA expression in both conditions. Among three possible YB-1 binding sites in the CCL5 promoter, a critical element was mapped at -28/-10 bps. This site allowed up-regulation of CCL5 transcription in monocytic THP-1 and HUT78 T-cells and in human primary monocytes; however, it repressed transcription in differentiated macrophages. Conversely, YB-1 knockdown led to decreased CCL5 transcription and secretion in monocytic cells. We show that YB-1 is a cell-type specific regulator of CCL5 expression in infiltrating T-cells and monocytes/macrophages and acts as an adaptive controller of inflammation during kidney allograft rejection.