Glomerular endothelium exhibits enhanced expression of costimulatory adhesion molecules, CD80 and CD86, by warm ischemia/reperfusion injury in rats

Lupus Nephritis: Immune Cells and the Kidney Microenvironment

Lupus nephritis (LN) is the most common major organ manifestation of the autoimmune disease SLE (lupus), with 10% of those afflicted progressing to ESKD. The kidney in LN is characterized by a significant immune infiltrate and proinflammatory cytokine milieu that affects intrinsic renal cells and is, in part, responsible for the tissue damage observed in LN. It is now increasingly appreciated that LN is not due to unidirectional immune cell activation with subsequent kidney damage. Rather, the kidney microenvironment influences the recruitment, survival, differentiation, and activation of immune cells, which, in turn, modify kidney cell function. This review covers how the biochemical environment of the kidney ( i.e ., low oxygen tension and hypertonicity) and unique kidney cell types affect the intrarenal immune cells in LN. The pathways used by intrinsic renal cells to interact with immune cells, such as antigen presentation and cytokine production, are discussed in detail. An understanding of these mechanisms can lead to the design of more kidney-targeted treatments and the avoidance of systemic immunosuppressive effects and may represent the next frontier of LN therapies.

Blood endothelium transition and phenotypic plasticity: A key regulator of integrity/permeability in response to ischemia

In the human body, the 1013 blood endothelial cells (ECs) which cover a surface of 500-700 m2 (Mai et al., 2013) are key players of tissue homeostasis, remodeling and regeneration. Blood vessel ECs play a major role in the regulation of metabolic and gaz exchanges, cell trafficking, blood coagulation, vascular tone, blood flow and fluid extravasation (also referred to as blood vascular permeability). ECs are heterogeneous in various capillary beds and have the exquisite capacity to cope with environmental changes by regulating their gene expression. Ischemia has major detrimental effects on the endothelium and ischemia-induced regulation of vascular integrity is of paramount importance for human health, as small amounts of fluid accumulation in the interstitium may be responsible for major effects on organ functions and patients outcome. In this review, we will here focus on the stimuli and the molecular mechanisms that control blood endothelium maintenance and phenotypic plasticity/transition involved in controlling blood capillary leakage that might open new avenues for therapeutic applications.

Angiotensin1-7 Protects Against Renal Ischemia-Reperfusion Injury via Regulating the Expression of NRF2 and microRNAs in Fisher 344 Rats

Ischemia/reperfusion (I/R) is considered the primary cause of acute kidney injury and is higher among older individuals. While ischemic episodes are hard to predict and prevent, detrimental ischemic effects could be mitigated by exogenous intervention. This study aims to identify the protective role of angiotensin (ANG)1-7 against I/R-induced renal injury in adult vs. aged rats. Adult and aged male Fisher 344 rats were subjected to 40-minute bilateral renal ischemia followed by 28-days reperfusion. ANG1-7 was administered intraperitoneally in ischemic rats for 28 days without or with Mas receptor antagonist A779. I/R increased blood pressure, plasma creatinine, urinary 8-isoprostane, and renal infiltration of pro and anti-inflammatory macrophages and reduced glomerular filtration rate in both adult and aged rats compared to shams. In addition to causing glomerular sclerosis and tubular damage, I/R increased the expression of pathogenic microRNAs (miRNAs): miR-20a-5p, miR-21-5p, miR-24-3p, and miR-194-5p in both the age groups. ANG1-7 treatment of ischemic rats mitigated oxidative stress and renal inflammation, restored renal structure and function, and reduced high blood pressure. Also, ANG1-7 suppressed the expression of pathogenic miRNAs. In addition, ANG1-7 treatment of I/R rats increased the expression of redox-sensitive transcription factor NRF2 and phase II antioxidant enzymes. The beneficial effects of ANG1-7 were sensitive to A779. Collectively, these data suggest that ANG1-7 associated with NRF2 activation could alleviate post-I/R-induced kidney injury and therefore serve as a potential therapeutic compound to protect against biochemical and morphological pathologies of I/R in both adults and aged populations.

Endothelial Cells Activated by Extracellular Histones Promote Foxp3+ Suppressive Treg Cells In Vitro

Histones are widely recognized as pro-inflammatory mediators upon their release from the nucleus into the extracellular space. However, their impact on endothelial cell immunogenicity is unknown. Endothelial cells, Human Microvascular Endothelial cells 1 (HMEC1), have been exposed to recombinant histones in order to study their effect on the endothelial phenotype. We then studied the differentiation of CD4⁺-T lymphocytes subpopulations after three days of interaction with endothelial cells in vitro and observed that histone-treated endothelial cells differentiate a suppressive FoxP3⁺ T regulator subpopulation that expressed Human Leucocyte Antigen DR (HLA-DR) and Cytotoxic T-Lymphocyte-Associated protein 4 (CTLA4). Toll-Like Receptor 4 (TLR4) inhibition significantly decreased the expansion of these Treg cells. Moreover, blockade of Interleukin (IL)-6 and Intercellular Adhesion Molecule (ICAM)-1 in cocultures significantly decreased the expansion of Tregs, suggesting an IL-6 and ICAM-1 dependent pathway. Thus, beyond their inflammatory effects, extracellular histones may induce an increase of immunosuppressive Treg population via their action on endothelial cells. Further studies are needed to evaluate the impact on immunosuppression of an increase of peripheral suppressive Treg via endothelial cell activation by histones in vivo.

Endothelial cells: potential novel regulators of renal inflammation

Substantial evidence has supported the role of endothelial cell (EC) activation and dysfunction in the development of hypertension, chronic kidney disease (CKD), and lupus nephritis (LN). In both humans and experimental models of hypertension, CKD, and LN, ECs become activated and release potent mediators of inflammation including cytokines, chemokines, and reactive oxygen species that cause EC dysfunction, tissue damage, and fibrosis. Factors that activate the endothelium include inflammatory cytokines, mechanical stretch, and pathological shear stress. These signals can activate the endothelium to promote upregulation of adhesion molecules, such as intercellular adhesion molecule-1 and vascular cell adhesion molecule-1, which promote leukocyte adhesion and migration to the activated endothelium. More importantly, it is now recognized that some of these signals may in turn promote endothelial antigen presentation through major histocompatibility complex II. In this review, we will consider in-depth mechanisms of endothelial activation and the novel mechanism of endothelial antigen presentation. Moreover, we will discuss these proinflammatory events in renal pathologies and consider possible new therapeutic approaches to limit the untoward effects of endothelial inflammation in hypertension, CKD, and LN.

Dual and Opposite Costimulatory Targeting with a Novel Human Fusion Recombinant Protein Effectively Prevents Renal Warm Ischemia Reperfusion Injury and Allograft Rejection in Murine Models

Many studies have shown both the CD28-D80/86 costimulatory pathway and the PD-1-PD-L1/L2 coinhibitory pathway to be important signals in modulating or decreasing the inflammatory profile in ischemia-reperfusion injury (IRI) or in a solid organ transplant setting. The importance of these two opposing pathways and their potential synergistic effect led our group to design a human fusion recombinant protein with CTLA4 and PD-L2 domains named HYBRI. The objective of our study was to determine the HYBRI binding to the postulated ligands of CTLA4 (CD80) and PD-L2 (PD-1) using the Surface Plasmon Resonance technique and to evaluate the in vivo HYBRI effects on two representative kidney inflammatory models-rat renal IRI and allogeneic kidney transplant. The Surface Plasmon Resonance assay demonstrated the avidity and binding of HYBRI to its targets. HYBRI treatment in the models exerted a high functional and morphological improvement. HYBRI produced a significant amelioration of renal function on day one and two after bilateral warm ischemia and on days seven and nine after transplant, clearly prolonging the animal survival in a life-sustaining renal allograft model. In both models, a significant reduction in histological damage and CD3 and CD68 infiltrating cells was observed. HYBRI decreased the circulating inflammatory cytokines and enriched the FoxP3 peripheral circulating, apart from reducing renal inflammation. In conclusion, the dual and opposite costimulatory targeting with that novel protein offers a good microenvironment profile to protect the ischemic process in the kidney and to prevent the kidney rejection, increasing the animal's chances of survival. HYBRI largely prevents the progression of inflammation in these rat models.

Markers of Endothelial Cells in Normal and Pathological Conditions

Endothelial cells (ECs) line the blood vessels and lymphatic vessels, as well as heart chambers, forming the border between the tissues, on the one hand, and blood or lymph, on the other. Such a strategic position of the endothelium determines its most important functional role in the regulation of vascular tone, hemostasis, and inflammatory processes. The damaged endothelium can be both a cause and a consequence of many diseases. The state of the endothelium is indicated by the phenotype of these cells, represented mainly by (trans)membrane markers (surface antigens). This review defines endothelial markers, provides a list of them, and considers the mechanisms of their expression and the role of the endothelium in certain pathological conditions.

Treg expansion with trichostatin A ameliorates kidney ischemia/reperfusion injury in mice by suppressing the expression of costimulatory molecules

Innate immune reactions are believed to be associated with ischemia/reperfusion injury (IRI), and IRI might be treatable by expanding regulatory T cells (Tregs), which can suppress the excessive responses of the immune system. Organ IRI is known to be closely involved in the expression of costimulatory molecules. The present study aimed to assess whether Tregs endogenously expanded by the administration of trichostatin A (TsA), a histone deacetylase inhibitor, could reduce renal IRI and to clarify their association with the expression of costimulatory molecules in a murine model. In this study, the wild-type mice used for an IRI model were randomly divided into the following four treatment groups: TsA group, DMSO group (control), DMSO+PC61 group, and TsA + PC61 group. Renal injury in the early phase after IRI was ameliorated in the TsA group (increased Tregs) when compared with the other groups. After renal IRI, both the mRNA and the protein levels of anti-inflammatory cytokines, IL-10 and TGF-β in the kidney and spleen were significantly higher in the TsA group than in the other groups, whereas the IL-6 levels were significantly lower in the TsA group than in the other groups. These results were offset by the administration of PC61, supporting that the renoprotective effect of TsA in this study is Treg dependent. mRNA expression levels of CD80, CD86, and ICAM-1 were lower in the TsA group, consistent with Treg control of injury through costimulatory molecules. Our findings suggest that endogenously expanded Tregs coordinate postischemic immune responses and decrease the expression of costimulatory molecules after renal IRI, and thus, they might ameliorate renal IRI. TsA administration for expanding Tregs is a promising therapeutic strategy for renal IRI.

Immune Consequences of Endothelial Cells' Activation and Dysfunction During Sepsis

The vascular endothelium provides a direct interface between circulating blood cells and parenchymal cells. Thus, it has a key role in vasomotor tone regulation, primary hemostasis, vascular barrier, and immunity. In the case of systemic inflammation, endothelial cell (EC) activation initiates a powerful innate immune response to eliminate the pathogen. In some specific conditions, ECs may also contribute to the activation of adaptive immunity and the recruitment of antigen-specific lymphocytes. However, the loss of EC functions or an exaggerated activation of ECs during sepsis can lead to multiorgan failure.

Epithelial CD80 promotes immune surveillance of colonic preneoplastic lesions and its expression is increased by oxidative stress through STAT3 in colon cancer cells

BACKGROUND

One of the most potent costimulatory molecules involved in the recognition and killing of tumor cells is CD80. However, its role and the molecular mechanisms regulating its expression in sporadic colorectal carcinogenesis remain elusive. Here, we provide evidence for CD80 overexpression in human colon epithelial cells derived from preneoplastic mucosa.

METHODS

Expression of CD80 on colonic epithelial cells isolated from normal human colonic mucosa, preneoplastic and neoplastic specimens was assessed by flow cytometry. WT and CD80KO mice received azoxymethane to induce colon preneoplastic lesions and sacrificed to perform histology, flow cytometry analysis and immunohistochemistry of colonic mucosa. Some WT mice were treated with a monoclonal anti-CD80 antibody following AOM administration. Primary colon epithelial cells and CT26 cell line were used to quantify the expression of CD80 in response to pro-oxidant stimuli. Specific pharmacological inhibitors and siRNA silencing were used to inhibit MAPK pathways and STAT3.

RESULTS

CD80 expression was significantly increased in colon epithelial cells of human preneoplastic lesions. In the AOM model, CD80 impairment by administration of neutralizing antibodies or use of CD80 knockout mice enhanced dysplasia development. In vitro, CD80 upregulation was induced by oxidative stress in colon cancer cells and primary colon epithelial cells. In addition, reactive oxygen species could induce CD80 expression via the JNK and p38 MAPK pathways, that activated STAT3 transcription factor in colon cancer epithelial cells.

CONCLUSION

This study provide evidence for a major role of CD80 in orchestrating immune surveillance of colon preneoplastic lesions and might help to develop novel approaches that exploit anti-tumor immunity to prevent and control colon cancer.

Markers and Biomarkers of Endothelium: When Something Is Rotten in the State

Endothelium is a community of endothelial cells (ECs), which line the blood and lymphatic vessels, thus forming an interface between the tissues and the blood or lympha. This strategic position of endothelium infers its indispensable functional role in controlling vasoregulation, haemostasis, and inflammation. The state of endothelium is simultaneously the cause and effect of many diseases, and this is coupled with modifications of endothelial phenotype represented by markers and with biochemical profile of blood represented by biomarkers. In this paper, we briefly review data on the functional role of endothelium, give definitions of endothelial markers and biomarkers, touch on the methodological approaches for revealing biomarkers, present an implicit role of endothelium in some toxicological mechanistic studies, and survey the role of reactive oxygen species (ROS) in modulation of endothelial status.

Endothelial Dysfunction and Inflammation: Immunity in Rheumatoid Arthritis

Inflammation, as a feature of rheumatoid arthritis (RA), leads to the activation of endothelial cells (ECs). Activated ECs induce atherosclerosis through an increased expression of leukocyte adhesion molecules. Endothelial dysfunction (ED) is recognized as a failure of endothelial repair mechanisms. It is also an early preclinical marker of atherosclerosis and is commonly found in RA patients. RA is now established as an independent cardiovascular risk factor, while mechanistic determinants of ED in RA are still poorly understood. An expanding body of study has shown that EC at a site of RA is both active participant and regulator of inflammatory process. Over the last decade, a role for endothelial dysfunction in RA associated with cardiovascular disease (CVD) has been hypothesized. At the same time, several maintenance drugs targeting this phenomenon have been tested, which has promising results. Assessment of endothelial function may be a useful tool to identify and monitor RA patients.

An evolving new paradigm: endothelial cells--conditional innate immune cells

Endothelial cells (ECs) are a heterogeneous population that fulfills many physiological processes. ECs also actively participate in both innate and adaptive immune responses. ECs are one of the first cell types to detect foreign pathogens and endogenous metabolite-related danger signals in the bloodstream, in which ECs function as danger signal sensors. Treatment with lipopolysaccharide activates ECs, causing the production of pro-inflammatory cytokines and chemokines, which amplify the immune response by recruiting immune cells. Thus, ECs function as immune/inflammation effectors and immune cell mobilizers. ECs also induce cytokine production by immune cells, in which ECs function as immune regulators either by activating or suppressing immune cell function. In addition, under certain conditions, ECs can serve as antigen presenting cells (antigen presenters) by expressing both MHC I and II molecules and presenting endothelial antigens to T cells. These facts along with the new concept of endothelial plasticity suggest that ECs are dynamic cells that respond to extracellular environmental changes and play a meaningful role in immune system function. Based on these novel EC functions, we propose a new paradigm that ECs are conditional innate immune cells. This paradigm provides a novel insight into the functions of ECs in inflammatory/immune pathologies.

Effect of ischemia preconditioning on renal ischemia/reperfusion injury in rats

OBJECTIVE

To study the effect of ischemia preconditioning (IP) on renal ischemia/reperfusion (I/R)-associated functional injury and expression of renal adhesion molecules in rats.

MATERIALS AND METHODS

The ischemia preconditioning plan adopted in this experiment involved renal warm ischemia for 6 min. and blood flow for 4 min., repeated four times. The Wistar rat kidneys used for warm ischemia preconditioning were subjected to 60 min of renal warm ischemia followed by reperfusion. The rat kidneys with ischemia/reperfusion were compared with the ischemia preconditioning group to observe rat renal function and changes in the expression of renal adhesion molecules ICAM-1, P-Selectin, and E-Selectin.

RESULTS

The expression of rat renal adhesion molecules (ICAM-1, P-Selectin, and E-Selectin) with ischemia preconditioning was significantly lower than that of the ischemia/reperfusion group. Serum creatinine was significantly lower than that in the ischemia/reperfusion group after 48 hours.

CONCLUSIONS

Ischemia preconditioning has a protective effect on renal function. Reduced expression of renal adhesion molecules is likely a mechanism involved in the observed protection.

B7-1 expression regulates the hypoxia-driven cytoskeleton rearrangement in glomerular podocytes

Chronic hypoxia has been recognized as a common mechanism driving the progression of many glomerular diseases. Glomerular cells, although susceptible to hypoxic injuries, are less studied to unravel the hypoxia-related influences. In the present study, we showed that both lipopolysaccharide (LPS) and hypoxia induced B7-1 and hypoxia-inducible factor (HIF)-1α expression in podocytes. B7-1, an essential player in the regulation of podocyte stress fibers, interacted directly with the NH(2)-terminal oxygenation domain of HIF-1α protein and, therefore, might interfere with the HIF-related oxidative events. The suggestion was supported by the changes in the expression of inducible nitric oxide synthase and nitric oxide. The orderly arranged stress fibers in differentiated podocytes were disrupted by either LPS or hypoxic stimulation, and the disruption could be rescued if they were brought back to normal oxygen tension. Cell motility increased with the stimulation by LPS and hypoxia, most probably mediated by the induction of B7-1 and HIF-1α, respectively. We generated a B7-1 knockdown podocyte cell line using the lentiviral small interfering RNA system. The LPS- and hypoxia-induced stress fiber disruption was largely prevented in the B7-1 knockdown podocytes. The increased cell motility by LPS and hypoxia stimulations was also ameliorated in the B7-knockdown podocytes. In summary, we found that both B7-1 and HIF were upregulated by LPS and hypoxic stimulations in podocytes and they interacted with each other. Hypoxia disrupted the abundant stress fibers and increased cell motility. These hypoxia-induced changes were prevented in B7-knockdown podocytes, and they highlighted the importance of B7-1 expression in the hypoxia-related podocyte injuries.

The osteoclast-associated receptor (OSCAR) is a novel receptor regulated by oxidized low-density lipoprotein in human endothelial cells

Cross talks between the vascular and immune system play a critical role in vascular diseases, in particular in atherosclerosis. The osteoclast-associated receptor (OSCAR) is a regulator of osteoclast differentiation and dendritic cell maturation. Whether OSCAR plays a role in vascular biology and has an impact on atherogenic processes provoked by proinflammatory stimuli is yet unknown. We identified OSCAR on the surface of human primary endothelial cells. Stimulation of endothelial cells with oxidized low-density lipoprotein (oxLDL) caused a time- and dose-dependent induction of OSCAR, which was lectin-like oxidized LDL receptor 1 and Ca(2+) dependent. OSCAR was transcriptionally regulated by oxLDL as shown by OSCAR promoter analysis. Specific inhibition of the nuclear factor of activated T cells (NFAT) pathway prevented the oxLDL-mediated increase of endothelial OSCAR expression. As assessed by EMSA, oxLDL induced binding of NFATc1 to the OSCAR promoter. Notably, in vivo-modified LDL from patients with diabetes mellitus stimulated OSCAR mRNA expression in human endothelial cells. Furthermore, apolipoprotein E knockout mice fed a high-fat diet showed an enhanced aortic OSCAR expression associated with increased expression of NFATc1. In summary, OSCAR is expressed in vascular endothelial cells and is regulated by oxLDL involving NFATc1. Our data suggest that OSCAR, originally described in bone as immunological mediator and regulator of osteoclast differentiation, may be involved in cell activation and inflammation during atherosclerosis.

CD4+CD25+Foxp3+ regulatory T cells protect the proinflammatory activation of human umbilical vein endothelial cells

OBJECTIVE

To investigate the role of CD4(+)CD25(+)forkhead box P 3 (Foxp3)(+) T-regulatory cells (Tregs) in protecting the activation and function of human umbilical vein endothelial cells (HUVECs) induced by proinflammatory stimulus and the mechanisms of it.

METHODS AND RESULTS

ECs play a major role in atherogenic initiation, changing their quiescence into activated phenotypes to support every phase of the inflammatory process. HUVECs were incubated alone, with Tregs or CD4(+)CD25(-) T cells in the presence of anti-CD3 monoclonal antibodies for 48 hours, and then were stimulated with or without oxidized low-density lipoprotein/lipopolysaccharide for an additional 24 hours. Tregs are able to induce alternative expression of immune phenotypic markers of activated HUVECs by down modulating CD86 and to inhibit the adhesion molecule, such as vascular cell adhesion molecule-1 (VCAM-1) and proinflammatory cytokine (eg, monocyte chemoattractant protein-1 and interleukin 6), response of HUVECs to oxidized low-density lipoprotein/lipopolysaccharide. Moreover, Tregs downregulate proinflammatory factor nuclear factor-κB activation and induce resistance to suppression of anti-inflammatory factor Kruppellike factor 2 in HUVECs induced by a proinflammatory stimulus. Mechanism studies reveal that Treg-mediated suppression of HUVEC proinflammatory cytokines and adhesion molecule expression impaired by oxidized low-density lipoprotein/lipopolysaccharide require cell contact by cytotoxic T-lymphocyte antigen-4 and CD86 and by soluble factors (mainly interleukin 10 and transforming growth factor [TGF]-β).

CONCLUSIONS

Tregs may exert their protective effects against atherogenesis in part through inducing an immune-inhibitory phenotype of ECs involving cytotoxic T-lymphocyte antigen-4-dependent cell-to-cell contact and also requiring soluble factors (mainly interleukin 10 and TGF-β).

Leukocyte recruitment and ischemic brain injury

Leukocytes are recruited into the cerebral microcirculation following an ischemic insult. The leukocyte-endothelial cell adhesion manifested within a few hours after ischemia (followed by reperfusion, I/R) largely reflects an infiltration of neutrophils, while other leukocyte populations appear to dominate the adhesive interactions with the vessel wall at 24 h of reperfusion. The influx of rolling and adherent leukocytes is accompanied by the recruitment of adherent platelets, which likely enhances the cytotoxic potential of the leukocytes to which they are attached. The recruitment of leukocytes and platelets in the postischemic brain is mediated by specific adhesion glycoproteins expressed by the activated blood cells and on cerebral microvascular endothelial cells. This process is also modulated by different signaling pathways (e.g., CD40/CD40L, Notch) and cytokines (e.g., RANTES) that are activated/released following I/R. Some of the known risk factors for cardiovascular disease, including hypercholesterolemia and obesity appear to exacerbate the leukocyte and platelet recruitment elicited by brain I/R. Although lymphocyte-endothelial cell and -platelet interactions in the postischemic cerebral microcirculation have not been evaluated to date, recent evidence in experimental animals implicate both CD4+ and CD8+ T-lymphocytes in the cerebral microvascular dysfunction, inflammation, and tissue injury associated with brain I/R. Evidence implicating regulatory T-cells as cerebroprotective modulators of the inflammatory and tissue injury responses to brain I/R support a continued focus on leukocytes as a target for therapeutic intervention in ischemic stroke.

VASCULAR INFLAMMATION AND ATHEROGENESIS ARE ACTIVATED VIA RECEPTORS FOR PAMPs AND SUPPRESSED BY REGULATORY T CELLS

Despite significant advances in identifying the risk factors and elucidating atherosclerotic pathology, atherosclerosis remains the leading cause of morbidity and mortality in industrialized society. These risk factors independently or synergistically lead to chronic vascular inflammation, which is an essential requirement for the progression of atherosclerosis in patients. However, the mechanisms underlying the pathogenic link between the risk factors and atherosclerotic inflammation remain poorly defined. Significant progress has been made in two major areas, which are determination of the roles of the receptors for pathogen-associated molecular patterns (PAMPs) in initiation of vascular inflammation and atherosclerosis, and characterization of the roles of regulatory T cells in suppression of vascular inflammation and atherosclerosis. In this review, we focus on three related issues: (1) examining the recent progress in endothelial cell pathology, inflammation and their roles in atherosclerosis; (2) analyzing the roles of the receptors for pathogen-associated molecular patterns (PAMPs) in initiation of vascular inflammation and atherosclerosis; and (3) analyzing the advances in our understanding of suppression of vascular inflammation and atherosclerosis by regulatory T cells. Continuous improvement of our understanding of the risk factors involved in initiation and promotion of artherogenesis, will lead to the development of novel therapeutics for ischemic stroke and cardiovascular diseases.

Chondrogenic differentiation alters the immunosuppressive property of bone marrow-derived mesenchymal stem cells, and the effect is partially due to the upregulated expression of B7 molecules

To investigate the immunosuppressive properties of MSCs, in the present study we examined the immunogenicity of undifferentiated and trilineage-differentiated (chondrocytes, osteoblasts, and adipocytes) rat bone marrow-derived MSCs under xenogeneic conditions. After chondrogenic differentiation, rat bone marrow-derived MSCs stimulated human dendritic cells (hDCs) derived from peripheral blood monocytes, leading to eight- and fourfold higher lymphocyte proliferation and cytotoxicity than that of undifferentiated MSCs. The chondrogenic-differentiated MSCs were chemotactic to hDCs in Dunn chamber chemotaxis system and were rosetted by hDCs in rosette assays. Flow cytometry analysis revealed that chondrogenic-differentiated MSCs had promoted hDC maturation, causing higher CD83 expression in hDCs, whereas undifferentiated MSCs and osteogenic- and adipogenic-differentiated MSCs showed an inhibitory effect on hDC maturation. The costimulatory B7 molecules were upregulated only in the chondrogenic-differentiated MSCs. After blocking B7 molecules with specific monoclonal antibodies in the chondrogenic-differentiated MSCs, CD83 expression of cocultured hDCs was greatly reduced. In conclusion, chondrogenic differentiation may increase the immunogenicity of MSCs, leading to stimulation of dendritic cells. The upregulated expression of B7 molecules on the chondrogenic-differentiated MSCs may be partially responsible for this event.

Effects of a phenolic compound, resveratrol, on the renal function and costimulatory adhesion molecule CD86 expression in rat kidneys with ischemia/reperfusion injury

Recent studies have suggested that an ischemia/reperfusion (I/R) injury enhances the expression of costimulatory adhesion molecules on the vascular endothelium. In the present study, we investigated the protective effects of resveratrol, a phenolic product, on the renal function and expression of CD86 in rat kidneys with I/R injury. Wistar rats were divided into four groups; 1) an I/R group with right nephrectomy and 1-hour clamping of the left renal pedicle; 2) a vehicle group, I/R plus 10% ethanol (0.1 ml/kg/day) administered by intra-peritoneal injection from day -1 through to 7; 3) a resveratrol group, I/R plus 4 mg/kg/day of resveratrol; and 4) a sham group. Blood samples were obtained via the tail vein at 1 day before, and 1, 3, and 7 days after the operation (day 0) for the measurement of serum creatinine (Scr) levels. The expression of CD86 protein was analyzed by immunofluorescence staining, and the level of CD86 messenger RNA (mRNA) was evaluated quantitatively by a real-time reverse transcription-polymerase chain reaction (RT-PCR) in the renal cortex at day 3. Scr levels of the resveratrol group were significantly lower than those of the I/R and vehicle groups on days 1 and 3 after the operation. From the immunohistochemical study, the expression of CD86 in the glomerular endothelium and peritubular vessels was found to be attenuated in the resveratrol group compared with the I/R or vehicle group. In the resveratrol group, the CD86 mRNA level was significantly lower than that in the I/R or vehicle group, and it was significantly decreased by about one fifth of that in the sham group. Our results suggest that resveratrol markedly reduces renal dysfunction and attenuates the mRNA and protein expression of CD86 following I/R injury.

Induction of B7-1 in podocytes is associated with nephrotic syndrome

Kidney podocytes and their slit diaphragms form the final barrier to urinary protein loss. This explains why podocyte injury is typically associated with nephrotic syndrome. The present study uncovered an unanticipated novel role for costimulatory molecule B7-1 in podocytes as an inducible modifier of glomerular permselectivity. B7-1 in podocytes was found in genetic, drug-induced, immune-mediated, and bacterial toxin-induced experimental kidney diseases with nephrotic syndrome. The clinical significance of our results is underscored by the observation that podocyte expression of B7-1 correlated with the severity of human lupus nephritis. In vivo, exposure to low-dose LPS rapidly upregulates B7-1 in podocytes of WT and SCID mice, leading to nephrotic-range proteinuria. Mice lacking B7-1 are protected from LPS-induced nephrotic syndrome, suggesting a link between podocyte B7-1 expression and proteinuria. LPS signaling through toll-like receptor-4 reorganized the podocyte actin cytoskeleton in vitro, and activation of B7-1 in cultured podocytes led to reorganization of vital slit diaphragm proteins. In summary, upregulation of B7-1 in podocytes may contribute to the pathogenesis of proteinuria by disrupting the glomerular filter and provides a novel molecular target to tackle proteinuric kidney diseases. Our findings suggest a novel function for B7-1 in danger signaling by nonimmune cells.

Induction of B7-1 in podocytes is associated with nephrotic syndrome

Kidney podocytes and their slit diaphragms form the final barrier to urinary protein loss. This explains why podocyte injury is typically associated with nephrotic syndrome. The present study uncovered an unanticipated novel role for costimulatory molecule B7-1 in podocytes as an inducible modifier of glomerular permselectivity. B7-1 in podocytes was found in genetic, drug-induced, immune-mediated, and bacterial toxin-induced experimental kidney diseases with nephrotic syndrome. The clinical significance of our results is underscored by the observation that podocyte expression of B7-1 correlated with the severity of human lupus nephritis. In vivo, exposure to low-dose LPS rapidly upregulates B7-1 in podocytes of WT and SCID mice, leading to nephrotic-range proteinuria. Mice lacking B7-1 are protected from LPS-induced nephrotic syndrome, suggesting a link between podocyte B7-1 expression and proteinuria. LPS signaling through toll-like receptor-4 reorganized the podocyte actin cytoskeleton in vitro, and activation of B7-1 in cultured podocytes led to reorganization of vital slit diaphragm proteins. In summary, upregulation of B7-1 in podocytes may contribute to the pathogenesis of proteinuria by disrupting the glomerular filter and provides a novel molecular target to tackle proteinuric kidney diseases. Our findings suggest a novel function for B7-1 in danger signaling by nonimmune cells.

Effect of tetramethylpyrazine on P-selectin and hepatic/renal ischemia and reperfusion injury in rats

AIM: To investigate the effect of tetramethylpyrazine on hepatic/renal ischemia and reperfusion injury in rats.

METHODS: Hepatic/renal function, histopathological changes, and hepatic/renal P-selectin expression were studied with biochemical measurement and immunohistochemistry in hepatic/renal ischemia and reperfusion injury in rat models.

RESULTS: Hepatic/renal insufficiency and histopathological damage were much less in the tetramethylpyrazine-treated group than those in the saline-treated groups. Hepatic/renal P-selectin expression was down regulated in the tetramethylpyrazine-treated group.

CONCLUSION: P-selectin might mediate neutrophil infiltration and contribute to hepatic/renal ischemia and reperfusion injury. Tetramethylpyrazine might prevent hepatic/renal damage induced by ischemia and reperfusion injury through inhibition of P-selectin.