Over-expression of AIF-1 in liver allografts and peripheral blood correlates with acute rejection after transplantation in rats

Over-Expression of Allograft Inflammatory Factor-1 (AIF-1) in Patients with Rheumatoid Arthritis

Allograft inflammatory factor-1 (AIF-1) is a cytoplasmic protein that is encoded by the AIF1 gene. The main functions of AIF-1 are the activation of macrophages and enhancing the production of pro-inflammatory cytokines. To date, three different AIF-1 isoforms have been identified. In this study, we examined the expression of AIF-1 isoforms on the level of mRNA, and we compared the percentage of AIF-1-positive white blood cells (WBCs) in blood and AIF-1/CD68 cells in the synovial membranes in patients with rheumatoid arthritis (RA) and osteoarthritis (OA). We examined 15 patients with RA and 15 patients with OA who had previously undergone knee arthroplasty. Peripheral blood and synovial membranes (SMs) were collected from these patients during knee arthroplasty. We identified three AIF-1 mRNA expression variants in peripheral mononuclear cells (PBMCs) and SMs from patients in both groups. Spearman’s rank correlation coefficient tests showed strong, positive, and significant correlations between the three AIF-1 mRNA expression variants in PBMCs and/or SMs in patients with RA and OA. There were no statistically significant correlations for any of the AIF-1 mRNA expression variants between PBMCs and SMs in patients with RA and OA. We observed a statistically significant increased percentage of AIF-1-positive cells in patients with RA in comparison to patients with OA. The percentage of AIF-1-positive cells in the blood of patients with RA and OA was 1.35 ± 0.81% and 0.71 ± 0.25% (p < 0.01), respectively, whereas the percentage of AIF-1/CD68-positive WBC cells in the SMs was 24.05 ± 7.17% and 4.78 ± 1.52% (p < 0.001), respectively. In conclusion, three AIF-1 mRNA expression variants occurred in PBMCs and SM cells in patients with RA and OA. The AIF-1 mRNA expression levels of the variants correlated with each other in PBMCs and SM cells, but there were no statistically significant correlations for AIF-1 mRNA expression variants between PBMCs and SM cells in patients with RA and OA. Both in the blood and SMs, we observed an increased percentage of AIF-1-positive cells in patients with RA in comparison to patients with OA. The above results suggested that AIF-1 was the cytokine involved in the pathogenesis of RA. The precise knowledge of the role of AIF-1 in RA pathogenesis and the development of inflammatory response requires further investigations.

AIF1 was identified as an up-regulated gene contributing to CSFV Shimen infection in porcine alveolar macrophage 3D4/21 cells

Classical swine fever (CSF) is a disease that is characterized by diffuse hemorrhaging, high fever, and high mortality rates. The pro-inflammatory characteristics of allograft inflammatory factor 1 (AIF1) have been well documented; however, insufficient attention has been given to porcine AIF1. In the present study, AIF1 was identified as a key player contributing to CSFV Shimen infection in porcine alveolar macrophage (PAM) 3D4/21 cell line. Our evaluation showed that AIF1 mRNA and protein are expressed at a time-dependent high level in CSFV Shimen-infected PAM 3D4/21 cells. The transcription and translation of IL6 were also significantly upregulated in infected PAM 3D4/21 cells. By utilizing overexpression RNAs approach, we showed that the cellular AIF1 induced an increased IL6 in PAM 3D4/21 cells. Furthermore, silencing of AIF1 suppressed CSFV Shimen-induced IL6 production in PAM 3D4/21 cells and also inhibited CSFV replication, whereas overexpression of recombinant AIF1 was beneficial for the replication of CSFV Shimen and promoting IL6 production in CSFV Shimen-infected PAM 3D4/21 cells. It is suggested CSFV Shimen induced IL6 in PAM 3D4/21 cells via AIF1 activation, which help clarify the AIF1-related inflammatory processes that occur on CSFV Shimen infected macrophages.

Extracellular allograft inflammatory factor-1 (AIF-1) potentiates Th1 cell differentiation and inhibits Treg response in human peripheral blood mononuclear cells from normal subjects

We identified the presence of AIF-1 (allograft inflammatory factor-1) in human peripheral blood mononuclear cells (PBMCs) from normal subjects by immunocytological methods. After isolation of different types of mononuclear cells by FACS (Fluorescence-activated cell sorting) with >95% purity, we studied the transcript levels of AIF-1 using qPCR. We observed the following order of AIF-1 mRNA expression in mononuclear cells: T-lymphocytes ˃ Monocytes ˃ B-lymphocytes ˃ NK. After T cell expansion of isolated PBMCs using anti-CD3-CD28 magnetic beads (Dynabeads®), AIF-1 increased intracellularly in the presence of brefeldin A; this finding, along with an increase in the medium in the absence of the drug, suggests that AIF-1 is processed in the Golgi apparatus and may be secreted extracellularly. In another set of experiments, interleukin-12 and anti-interleukin-4 were added to PBMCs during T cell expansion to promote Th1 polarization and to inhibit Th2 differentiation. In this case, the presence of 6 nM of rhAIF-1 (recombinant human AIF-1) increased the mRNA expression of interferon-ϒ and interleukin-2. In the same set of experiments, the incubation of PBMCs with rhAIF-1 (6 nM) promoted the decrease of mRNA expression of IL-10 and TGF-β, along with the decrease of CD25 and Foxp3 proteins. Furthermore, extracellular rhAIF-1 (6 nM) increased the survival of naive and effector T cells during Th1 polarization by inhibition of apoptosis, without causing changes in cell cycle rate and in retinoblastoma-cyclin-dependent kinase (Rb-CDK) activation. Taken together, rhAIF-1 treatment of PBMCs potentiates Th1 response and inhibits functionally suppressive CD25 + Foxp3 + Treg, which suggests an important immunomodulatory role in governing T cell response.

Stimulator of interferon genes (STING) activation exacerbates experimental colitis in mice

Detection of cytoplasmic DNA by the host’s innate immune system is essential for microbial and endogenous pathogen recognition. In mammalian cells, an important sensor is the stimulator of interferon genes (STING) protein, which upon activation by bacterially-derived cyclic dinucleotides (cDNs) or cytosolic dsDNA (dsDNA), triggers type I interferons and pro-inflammatory cytokine production. Given the abundance of bacterially-derived cDNs in the gut, we determined whether STING deletion, or stimulation, acts to modulate the severity of intestinal inflammation in the dextran sodium sulphate (DSS) model of colitis. DSS was administered to Tmem173^gt (STING-mutant) mice and to wild-type mice co-treated with DSS and a STING agonist. Colitis severity was markedly reduced in the DSS-treated Tmem173^gt mice and greatly exacerbated in wild-type mice co-treated with the STING agonist. STING expression levels were also assessed in colonic tissues, murine bone marrow derived macrophages (BMDMs), and human THP-1 cells. M1 and M2 polarized THP-1 and murine BMDMs were also stimulated with STING agonists and ligands to assess their responses. STING expression was increased in both murine and human M1 polarized macrophages and a STING agonist repolarized M2 macrophages towards an M1-like subtype. Our results suggest that STING is involved in the host’s response to acutely-induced colitis.

Expression of Allograft Inflammatory Factor-1 (AIF-1) in Hepatocellular Carcinoma

Background

Allograft inflammatory factor-1 (AIF-1) is a cytoplasmic protein cloned from activated macrophages in human and rat allografts. AIF-1 has been identified as a modulator of inflammatory response, and recently published studies have shown its increased expression in carcinogenesis. However, there are still limited data on the potential functional role of AIF-1 in hepatocellular carcinoma (HCC).

Material/Methods

We evaluated the expression of AIF-1 in 104 cases of paired HCC and adjacent non-cancerous liver tissues using immunohistochemistry, Western blotting, and qPCR analysis, and sought to determine whether its expression was correlated with clinicopathological features. In vitro assays, including cell proliferation and migration assays, were used to study the effects of AIF-1 knockdown in L02 human hepatocyte, and Huh7 and SMMC7721 liver cancer cell lines.

Results

Expression of AIF-1 was increased in HCC compared to adjacent normal liver tissues and was positively correlated with median tumor size (p=0.046), number of tumor deposits (p=0.009), the Barcelona Clinic Liver Cancer (BCLC) stage (p=0.004), and portal vein tumor thrombus (PVTT) (p<0.001). Huh7 and SMMC7721 human HCC cells demonstrated upregulated AIF-1 expression compared to normal hepatocytes. Small interfering RNA (siRNA)-mediated silencing of AIF-1 expression resulted in a reduction in cell proliferation and migration in human HCC cells.

Conclusions

These findings suggest AIF-1 may have roles as a diagnostic or prognostic biomarker and a promising therapeutic target in HCC.

Functional Identification of Allograft Inflammatory Factor 1-Like Gene in Luning Chicken

Allograft inflammatory factor-1 (AIF-1) is an inflammation-related protein mainly produced by immune cells, such as monocyte/macrophages and activated T lymphocytes. It is essential for the survival and proinflammatory activity of immune cells. However, the function of AIF-1 in chicken still has not been defined. In the present study, AIF-1-like (AIF1L) gene was identified in Luning chicken. Bioinformatics analysis revealed that the molecular weight of the chicken AIF-1 protein was 16290.8 Da. AIF1L contained a Ca²⁺ binding EF hand and could interact with actin filament. Its transcript was found in all tested tissues including spleen, brain, heart, kidney, liver, thymus, bursa of Fabricius, lung, and a relative low-level expression was detected in leg muscle. Furthermore, AIF1L expression in peripheral blood lymphocyte was depressed in a dose-dependent manner with cadmium exposure and peripheral blood lymphocyte viability decrease displayed a similar pattern with AIF1L expression. The results indicated that newly identified chicken AIF1L might be associated with lymphocyte viability.

Identification of hub genes related to silicone-induced immune response in rats

Silicone implants are used widely in the field of plastic surgery and are used in a large population. However, their safety profile, especially the silicone-induced immune response, has been a major concern for plastic surgeons for decades. It has been hypothesized that there is a cause and effect relation between silicone and immunity, but this is controversial. The objective of the present study was to determine the hub genes and key pathways related to silicone implant–induced immune responses in a rat model. In addition to cluster and enrichment analyses, we used weighted gene co-expression network analysis (WGCNA) to examine the gene expression profiles in a systematic context. A total five genes (Fes, Aif1, Gata3, Tlr6, Tlr2) were identified as hub genes that are most likely related to the silicone-induced immune response, four of which (Aif1, Gata3, Tlr6, Tlr2) have been associated with autoimmunity as target genes or disease markers. The Toll-like receptor signaling pathway (p < 0.01, fold enrichment: 7.01) and systemic lupus erythematosus signaling pathway (p < 0.05, fold enrichment: 5.01), which are considered strongly associated with autoimmunity, were significantly enriched in the silicone-implanted skin samples. The results indicate that silicone implants might trigger the localized immune response, as various immune reaction genes were detected after silicone implantation. The identified five hub genes will hopefully serve as novel therapeutic targets for silicone-related complications and the associated autoimmune diseases.

Allograft inflammatory factor-1 in the pathogenesis of bleomycin-induced acute lung injury

Allograft inflammatory factor-1 (AIF-1) is a protein expressed by macrophages infiltrating the area around the coronary arteries of rats with an ectopic cardiac allograft. Some studies have shown that expression of AIF-1 increased in a mouse model of trinitrobenzene sulfonic acid-induced acute colitis and in acute cellular rejection of human cardiac allografts. These results suggest that AIF-1 is related to acute inflammation. The current study used bleomycin-induced acute lung injury to analyze the expression of AIF-1 and to examine its function in acute lung injury. Results showed that AIF-1 was significantly expressed in lung macrophages and increased in bronchoalveolar lavage fluid from mice with bleomycin-induced acute lung injury in comparison to control mice. Recombinant AIF-1 increased the production of IL-6 and TNF-α from RAW264.7 (a mouse macrophage cell line) and primary lung fibroblasts, and it also increased the production of KC (CXCL1) from lung fibroblasts. These results suggest that AIF-1 plays an important role in the mechanism underlying acute lung injury.

Daintain/AIF-1 accelerates the activation of insulin-like growth factor-1 receptor signaling pathway in HepG2 cells

Daintain/allograft inflammatory factor-1 (AIF-1), as a novel inflammatory factor, has been reported to accelerate the proliferation and migration of breast cancer cells. However, the effect of daintain/AIF-1 on hepatocarcinogenesis remains unclear. In order to explore the effect of daintain/AIF-1 on the progression of hepatocellular carcinoma (HCC), enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR) were performed to examine the secretion and gene expression of (IGF)-1, IGF-2 and IGFBP-3. The expression of IGF-1R and its downstream targets was evaluated by western blotting. In addition, the proliferation and cell-cycle progression of HepG2 cells was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenylterazolium bromide (MTT) and flow cytometric analysis. The results showed that HepG2 cells subjected to daintain/AIF-1 treatment revealed an obvious increase in the secretion of IGF-1 and IGF-2, and a reduction in the secretion of IGFBP-3. Moreover, daintain/AIF-1 accelerated the activation of IGF-1-induced IGF-1R and its downstream AKT signaling pathway, and subsequently promoted the activation of cyclin D1 pathway, thus accelerating the progression of the cell cycle and eventually promoting the proliferation of HepG2 cells. In conclusion, daintain/AIF-1 promoted the proliferation of HepG2 cells by accelerating the activation of IGF-1R and its downstream signaling pathway, which confirms that daintain/AIF-1 plays a crucial role in the development of HCC.

Genetic inactivation of the allograft inflammatory factor-1 locus

Allograft inflammatory factor-1 (Aif-1) is a 17 kDa EF hand motif-bearing protein expressed primarily in developing spermatids and cells of monocyte/macrophage lineage. Increased Aif-1 expression has been identified in clinically important conditions, including rheumatoid arthritis, systemic sclerosis, endometriosis, and transplant-associated arteriosclerosis. Largely similar gene products arising from the same locus are known as ionized Ca(2+) binding adapter-1 (Iba1), microglial response factor-1 (MRF1), and daintain; Iba1 in particular has emerged as a histologic marker of microglia and their activation in pathologic CNS conditions, including the response to facial nerve axotomy and stroke, uveitis, and experimental autoimmune neuritis and encephalomyelitis. Nevertheless, how aif-1 gene products affect cellular function is only partly understood, and the physiologic significance of these products for male fertility, immune system development, and inflammation has not been described. To permit such investigations, we generated a mouse line with targeted deletion of the coding regions of the aif-1 gene. Here we report that mice lacking Aif-1 breed well and show normal post-natal growth, but show resistance to disease in a model of collagen-induced arthritis. We anticipate that these mice will be useful for studies of Aif-1 function in a variety of immune and inflammatory disease models.

Daintain/AIF-1 promotes breast cancer cell migration by up-regulated TNF-α via activate p38 MAPK signaling pathway

Tumor-associated macrophages can release a vast diversity of growth factors, proteolytic enzymes, cytokines, and inflammatory mediators. Many of these factors are key agents in cancer metastasis. Daintain/AIF-1 is a macrophage-derived inflammatory cytokine which defined a distinct subset of tumor-associated activated macrophages/microglial cells. Previous study demonstrated that daintain/AIF-1 could promote breast cancer proliferation through activating NF-κB/cyclin D1 pathway and facilitate tumor growth. However, the effect of Daintain/AIF-1 on cell migration and cancer metastasis has never been reported. Herein, we used a mimic tumor microenvironment by incubating breast cancer cell lines, MDA-MB-231 and MCF-7 cells, with macrophage-conditioned medium with or without purified daintain/AIF-1 polypeptide to evaluate cell migration. Results indicated that daintain/AIF-1 enhanced the migration of MDA-MB-231 and MCF-7 cells in the manner of TNF-α up-regulation. Further study found that daintain/AIF-1 activates p38 MAPK signaling pathway contributing to up-regulation of TNF-α in MDA-MB-231 and MCF-7 cells. Therefore, this novel daintain/AIF-1-p38-TNF-α pathway and insight into daintain/AIF-1 might have potential benefits in the control of tumor metastasis during cancer therapy.

B-cell immunity in the context of T-cell tolerance after combined kidney and bone marrow transplantation in humans

Five patients with end-stage kidney disease received combined kidney and bone marrow transplants from HLA haploidentical donors following nonmyeloablative conditioning to induce renal allograft tolerance. Immunosuppressive therapy was successfully discontinued in four patients with subsequent follow-up of 3 to more than 6 years. This allograft acceptance was accompanied by specific T-cell unresponsiveness to donor antigens. However, two of these four patients showed evidence of de novo antibodies reactive to donor antigens between 1 and 2 years posttransplant. These humoral responses were characterized by the presence of donor HLA-specific antibodies in the serum with or without the deposition of the complement molecule C4d in the graft. Immunofluorescence staining, ELISA assays and antibody profiling using protein microarrays demonstrated the co-development of auto- and alloantibodies in these two patients. These responses were preceded by elevated serum BAFF levels and coincided with B-cell reconstitution as revealed by a high frequency of transitional B cells in the periphery. To date, these B cell responses have not been associated with evidence of humoral rejection and their clinical significance is still unclear. Overall, our findings showed the development of B-cell allo- and autoimmunity in patients with T-cell tolerance to the donor graft.

Gene expression profiling of acute cellular rejection in rat liver transplantation using DNA microarrays

Acute cellular rejection (ACR) is still a major problem in organ transplantation, and its genetic and molecular mechanisms remain poorly understood. We used DNA microarrays to investigate the gene expression profiles in ACR. We hypothesized that changes of gene expression in grafts could also be detected in peripheral blood leukocytes. We first compared the gene expression profiles in liver isografts (Lewis to Lewis) and allografts (Dark Agouti to Lewis) harvested from rats at days 1, 3, 5, and 7 after transplantation. Hierarchical clustering analysis indicated that gene expression started to change on day 3, and 89 differentially expressed genes were extracted from allografts in comparison with isografts at day 3. Most of the up-regulated genes were associated with graft-infiltrating leukocytes. We then confirmed the similarity of gene expression changes in peripheral leukocytes by quantitative real-time polymerase chain reaction. We also investigated the gene expression changes in other inflammatory and liver dysfunction models. Two interferon-gamma inducible genes, interferon regulatory factor 1 and guanylate nucleotide binding protein 2, were overexpressed in both the peripheral leukocytes and liver graft during ACR. Although further studies are necessary, these 2 genes in peripheral leukocytes could be potentially useful markers for rejection or immunosuppression.

Recruitment of host progenitor cells in rat liver transplants

Despite major histocompatibility complex incompatibility, liver transplants from Lewis rats to dark agouti (DA) rats survive indefinitely without immunosuppression, and the studies we report sought the mechanism(s) responsible for this. At 1 year, most of the liver reacted positively to host anti-DA antibody. When small (50%) grafts were transplanted, recruitment was more rapid because most of the organ assumed the host phenotype at 3 months. After transplantation, the Y chromosome was detected in the hepatocytes of XX to XY grafts by both in situ hybridization and polymerase chain reaction. Further, livers from transgenic Lewis rats carrying strong green fluorescent protein (GFP) markers lost the marker with time after transplantation to DA, GFP-negative hosts. Few liver cells contained the Y chromosome in syngeneic XX to XY liver grafts or when the hosts of Lewis XX to DA XY allografts were treated with cyclosporine A at 10 mg/kg/day. This dosage also impeded enlargement of the liver at 10 days. Using GFP-positive XX Lewis donors transplanted to GFP-negative XY DA hosts, we found little Y DNA in GFP-positive cells at 10 days. Host-derived OV-6-positive and c-kit-positive, albumin-positive cells were present at 3-10 days, but cells with the CD34 marker were less common and some clearly still had the donor phenotype at 10 days. Cells positive for chemokine cysteine-X-cysteine receptor-4 increased with time and were abundant 1 month after transplantation. We conclude: (1) extrahepatic cells can differentiate into liver tissues; (2) regenerative stimuli accelerate stem cell recruitment; (3) both regeneration and recruitment are impeded by cyclosporine A immunosuppression, and (4) donor GFP-positive cells contained little host Y chromosome after transplantation, suggesting that cell fusion was uncommon and, therefore, unlikely to be the mechanism leading to the changes in genotype and phenotype we observed.

Immunologic role of Kupffer cells in liver transplantation

Orthotopic liver transplantation (OLT) is an effective treatment for the end-stage liver diseases. Rejection reaction of graft remains a major cause of post-transplantation liver dysfunction and even failure. Immunologic role of Kupffer cells in liver transplantation is frequently ignored. Many investigations demonstrated that Kupffer cells activate T cells through direct antigen presentation, and aggravate transplantation rejection reaction. At the same time, Kupffer cells may induce apoptosis of T cells by FasL and evoke transplantation tolerance. This review discusses the immunologic role of Kupffer cells in liver transplantation.

Allograft inflammatory factor-1/Ionized calcium-binding adapter molecule 1 is specifically expressed by most subpopulations of macrophages and spermatids in testis

Ionized calcium-binding adapter molecule 1 (Iba1) is a 147-amino-acid calcium-binding protein widely in use as a marker for microglia. It has actin-crosslinking activity and is involved in aspects of motility-associated rearrangement of the actin cytoskeleton. The Iba1 gene and protein are identical to allograft inflammatory factor-1 (AIF-1), a protein involved in various aspects of inflammation, which was investigated independently from Iba1. Although regarded to be monocyte/macrophage-specific, expression by germ cells in testis showed that AIF-1/Iba1 is not exclusively expressed by cells of the monocyte/macrophage lineage. Furthermore, AIF-1 was found in cells not belonging to the monocyte/macrophage lineage under pathological conditions. Here, the distribution of AIF-1/Iba1 in the normal mouse has been examined, by immunohistochemistry, to determine whether AIF-1/Iba1 expression is confined to macrophages and spermatids. Spermatids are the only cells not belonging to the monocyte/macrophage lineage found to express AIF-1/Iba1 in the normal mouse, by this method. This study has not demonstrated AIF-1/Iba1 expression in dendritic cells, although this protein might be expressed by subsets of dendritic cells. AIF-1/Iba1 can be regarded a "pan-macrophage marker" because, except for alveolar macrophages, all subpopulations of macrophages examined express AIF-1/Iba1.

Allograft inflammatory factor-1 and its immune regulation

The allograft inflammatory factor-1 (AIF-1) is a 17 kDa interferon-gamma (IFN-gamma) inducible Ca(2+)-binding EF-hand protein that is encoded within the HLA class III genomic region. Three proteins including ionized Ca(2+)-binding adaptor 1, microglia response factor-1, and daintain are identical with AIF-1. The expression of AIF-1 was mostly limited to the monocyte/macrophage lineage, and augmented by cytokines such as IFN-gamma. It was assumed that AIF-1 was a novel molecule involved in inflammatory responses, allograft rejection, as well as the activation and function of macrophages. However, it has been reported that AIF-1 is also expressed in macrophages and microglial cells in autoimmune diseases such as experimental autoimmune encephalomyelitis, neuritis and uveitis models, suggesting that AIF-1 may play a pivotal role in autoimmunity. In the present manuscript, the genomic and functional characteristics of AIF-1 family proteins as well as their immune regulatory effects are reviewed.

Induction of long-term liver allograft survival by delayed immunosuppression is dependent on interleukin-10

This study aims to investigate the potential role of endogenous interleukin (IL)-10 in long-term liver allograft survival induced by delayed immunosuppression (FK506 days 2-7). Liver transplantation was performed by using Dark Agouti and Lewis rats as donors and recipients, respectively. The delayed immunosuppression protocol induced indefinite allograft survival. A transient upregulation of plasma IL-10 levels was detected in the nontreatment and FK506 treatment groups. Macrophages were found to be one of the major sources of IL-10 produced from the liver allografts. Administration of IL-10-neutralizing antibody shortened the long-term isograft survival and FK506-induced indefinite allograft survival, particularly in the FK506 group. Damaged liver graft histology and increase of plasma alanine aminotransferase levels were detected in the groups with IL-10 antibody treatment. In an ex vivo setting, IL-10 recombinant protein augmented the expression of Foxp3, downregulated the expression of IL-2 and interferon gamma, and induced the generation of CD4(+)CD25(+)Foxp3(+) and CD8(+)CD25(+)Foxp3(+) cells, but this effect was blocked by the administration of IL-10 antibody. Finally, administration of IL-10 recombinant protein after the decline of endogenous IL-10 levels improved allograft survival, and a 100% long-term allograft survival was achieved by the combination of IL-10 with low-dose FK506. In conclusion, the delayed immunosuppression could induce long-term liver allograft survival in the presence of endogenous IL-10 produced by the tissue macrophages. Supplementary exogenous IL-10 administration combined with low-dose immunosuppressive drug may be a useful strategy to induce long-term liver allograft survival.

Antiinflammatory properties of IL-10 rescue small-for-size liver grafts

The present study aims to investigate the potential therapeutic role of interleukin-10 (IL-10) in small-for-size liver transplantation. A syngenic rat orthotopic liver transplantation model was performed using either whole or 40% liver volume of Lewis rats as grafts according to the experimental design. IL-10 was given to the 40% grafts right after reperfusion, and also at 24 and 48 hours after transplantation. When no treatment was given, less than 40% of the small-for-size grafts survived indefinitely, whereas IL-10 treatment could increase the long-term survival rate of the small-for-size grafts to 80%. The 40% grafts presented with extensive areas of necrosis and increased number of apoptotic cells at the early phases after reperfusion. In addition, upregulation of plasma protein carbonyl content (PCC) levels was also detected in the 40% graft group. IL-10 treatment suppressed the upregulation of allograft inflammatory factor-1 (AIF-1) on macrophages in the 40% grafts, and at the same time, decreased the levels of plasma PCC, and improved the histology and function of the 40% grafts. The expression of inducible nitric oxide synthase (iNOS), tumor necrosis factor (TNF)-alpha, and caspase 9 in the 40% grafts were upregulated after reperfusion, whereas the augmentation could be suppressed by the administration of IL-10. Finally, IL-10 culture could block AIF-1-mediated NO production and downregulate the expression of iNOS and TNF-alpha in a macrophage cell line. In conclusion, IL-10 rescued the small-for-size liver grafts by its antiinflammatory properties, through inhibition of AIF-1 mediated proinflammatory and proapoptotic activities of the macrophages during the early period after ischemia/reperfusion.

Expression of allograft inflammatory factor-1 in kidneys: A novel molecular component of podocyte

Our comprehensive gene expression profiles of the kidneys in an anti-glomerular basement membrane (GBM) nephritis model using DNA arrays revealed that allograft inflammatory factor-1 (AIF-1) was one of the highly expressed genes. Here, we explored the pathological significance of AIF-1 expression in the kidneys. The expression pattern of AIF-1 mRNA and protein in the kidneys of normal and diseased rats, such as anti-GBM nephritis and puromycin aminonucleoside nephrosis, was investigated by in situ hybridization, immunohistochemistry, and immunoelectron microscopy. Furthermore, the expression of AIF-1 in human kidneys and urinary sediments was examined. AIF-1 was expressed at both mRNA and protein levels in podocytes of normal and diseased rats, and in infiltrating cells in anti-GBM nephritis kidneys. The expression of AIF-1 in podocytes was constitutive; positive in podocytes of both normal and diseased rats. In humans, AIF-1 was expressed in podocytes and infiltrating inflammatory cells, similarly. Moreover, it was detected in urinary podocytes from patients with immunoglobulin A nephropathy. These data document for the first time that AIF-1, a constitutively expressed protein in rat and human podocytes, is a novel molecular component of podocytes, and that the upregulation of AIF-1 in an anti-GBM nephritis model may mainly be a consequence of its expression in infiltrating cells.

Expression of allograft inflammatory factor 1 in tissues from patients with systemic sclerosis and in vitro differential expression of its isoforms in response to transforming growth factor beta

OBJECTIVE

Allograft inflammatory factor 1 (AIF-1), a protein initially identified in chronically rejected rat cardiac allografts, is involved in the immune response and proliferative vasculopathy that occurs during allograft rejection. Three well-characterized isoforms of AIF-1 result from alternative messenger RNA (mRNA) splicing. We previously identified a strong association of systemic sclerosis (SSc) with a polymorphism in AIF-1 isoform 2. The purpose of this study was to investigate AIF-1 expression in affected tissues from patients with SSc and to examine the regulation of its isoforms by transforming growth factor beta (TGFbeta).

METHODS

AIF-1 in the skin and lung tissues of patients with SSc was analyzed by immunochemistry. AIF-1 isoform expression in response to TGFbeta and interferon-gamma stimulation was examined by quantitative polymerase chain reaction (PCR).

RESULTS

AIF-1 protein was present in affected vessels of the lung and skin lesions of patients with SSc. Quantitative PCR showed an average of 14-fold higher mRNA levels in affected SSc skin than in normal skin. Double-label immunofluorescence staining demonstrated that T cells, macrophages, and endothelial cells in affected tissues expressed AIF-1. Stimulation of peripheral blood mononuclear cells with TGFbeta caused a specific and significant increase in the expression of AIF-1 isoform 2 transcripts (P < 0.005), which was due to stabilization of AIF-1 isoform 2 mRNA.

CONCLUSION

These data suggest that AIF-1 plays an important role in the pathogenesis of SSc owing to its increased expression in affected tissues and to the specific stimulation of AIF-1 isoform 2 by TGFbeta.

Warm ischemia-induced alterations in oxidative and inflammatory proteins in hepatic Kupffer cells in rats

The aim of the study was to investigate the impact of ischemia/reperfusion injury on the proteome of Kupffer cells. Lean Zucker rats (n = 6 each group) were randomized to 75 min of warm ischemia or sham operation. After reperfusion for 8 h, Kupffer cells were isolated by enzymatic perfusion and density gradient centrifugation. Proteins were tryptically digested into peptides and differentially labeled with iTRAQ (isobaric tags for relative and absolute quantitation) reagent. After fractionation by cation exchange chromatography, peptides were identified by mass spectrometry (ESI-LC-MS/MS). Spectra were interrogated against the Swiss-Prot database and quantified using ProteinProspector. The results for heat shock protein 70 and myeloperoxidase were validated by ELISA. Quantitative information for more than 1559 proteins was obtained. In the ischemia group proteins involved in inflammation were significantly up-regulated. The ratio for calgranulin B in the ischemia/sham group was 1.81 +/- 0.97 (p < 0.0001), for complement C3 the ratio was 1.81 +/- 0.49 (p < 0.0001), and for myeloperoxidase the ratio was 1.30 +/- 0.32. Myeloperoxidase was only recently documented in Kupffer cells. The antioxidative proteins Cu,Zn-superoxide dismutase (1.34 +/- 0.19; p < 0.001) and catalase (1.23 +/- 0.43; p < 0.001) were also elevated. In conclusion, ischemia/reperfusion injury induces alterations in the Kupffer cell proteome. Isotope ratio mass spectrometry is a powerful tool to investigate these reactions. The ability to simultaneously monitor several pathways involved in reperfusion stress may result in important mechanistic insight and possibly new treatment options.

Oxidative mitochondrial DNA damage and deletion in hepatocytes of rejecting liver allografts in rats: role of TNF-alpha

An orthotopic liver transplant model in the rat was used to evaluate the role of tumor necrosis factor alpha (TNF-alpha) in liver transplant rejection. There were significantly increased levels of TNF-alpha mRNA and parallel increases in 8-hydroxy-2' deoxyguanosine (8-OHdG) indicative of oxidative DNA damage present 7 to 12 days after transplantation. Cells staining positively for 8-OHdG were localized to the cytoplasm of hepatocytes adjacent to the TNF-alpha expressing inflammatory cells in the portal areas or in patches surrounded by inflammatory cells in the hepatic sinusoids. Significantly more cells staining for 8-OHdG were found in the allogeneic grafts that were strongly rejected than in the syngeneic controls or in the grafts placed in species that accepted the allograft permanently after a rejection episode. TUNEL reactivity lagged 2 days behind peak reactivity for 8-OHdG. On day 12 after transplantation, many cells stained for both 8-OHdG and TUNEL, indicating that the cells suffering oxidative DNA injury were undergoing apoptosis or death. Oxidative injury resulted in mtDNA deletion consisting of 4,834 base-pairs. Studies of hepatocytes cultured from normal rats displayed dose-dependent relationships between TNF-alpha concentration and 8-OHdG and mtDNA mutation. Repetitive intraperitoneal injection of Enbrel, a TNF receptor blocker, significantly decreased hepatocyte 8-OHdG levels and the frequency of deleted mtDNA while greatly extending graft survival time. In conclusion, the data presented implicate TNF-alpha as being capable of causing oxidative DNA damage and mtDNA mutation in hepatocytes.