IL-17 expression by tubular epithelial cells in renal transplant recipients with acute antibody-mediated rejection.

Acute rejection is still a common complication of kidney transplantation. IL-17 is known to be associated with allograft rejection but the cellular source and the role of this cytokine remains unclear. We investigated IL-17 graft expression in renal transplant recipients with acute antibody-mediated rejection (ABMR), acute T-cell-mediated rejection (TCMR), interstitial fibrosis and tubular atrophy (IFTA) and acute tubular damage due to calcineurin-inhibitor toxicity (CNI). In acute ABMR, tubular IL-17 protein expression was significantly increased compared to TCMR, where most of the IL-17⁺ cells were CD4⁺ graft infiltrating lymphocytes, IFTA and CNI control groups. The tubular expression of IL-17 in acute ABMR colocalized with JAK2 phosphorylation and peritubular capillaries C4d deposition. In addition, IL-17 tubular expression was directly and significantly correlated with the extension of C4d deposits. In cultured proximal tubular cells, C3a induced IL-17 gene and protein expression along with an increased in JAK2 phosphorylation. The inhibition of JAK2 abolished C3a-induced IL-17 expression. The use of steroids and monoclonal antibodies reduced IL-17 expression, JAK2 phosphorylation and C4d deposition in acute ABMR patients. Our data suggest that tubular cells represent a significant source of IL-17 in ABMR and this event might be mediated by the complement system activation featuring this condition.

Activation of PI3-kinase/Akt induced small bowel cell apoptosis during laparoscopic ischaemia-reperfusion of swine jejunum.

INTRODUCTION: This study aimed to detect small bowel cell apoptosis by evaluating the nuclear activation of transcription factors, nuclear factor-kappaB (NF-kappaB) and Akt pathways as well as detecting apoptotic cells by TUNEL assay, during ischaemia-reperfusion (I/R) injury by Arterio-Venous Occlusion (AVO) of ajejunal loop in swine, using a laparoscopic procedure. MATERIALS AND METHODS: A jejunal loop was isolated and a biopsy sample (T0) obtained. Biopsies were obtained at 30 minutes (T30I) and 60 minutes (T60I) after clamping and again during reperfusion (R), T30R and T60R. Standard H&E stains and immunohistochemical study for infiltrating polymorphonuclear leukocytes and TUNEL assays were performed. The activation of Akt and NF-kappaB in the animal model was evaluated by indirect immunofluorescence and confocal microscopy. CONCLUSIONS: Our results confirmed that I/R injury of the jejunum did not only cause epithelial damage, but also activated the molecular pathways triggering an apoptotic reaction (by pro-inflammatory cytokines) and an anti-apoptotic mechanism that can lead to the regeneration of injured tissue.

ID2-VEGF-related pathways in the pathogenesis of Kaposi's sarcoma: a link disrupted by rapamycin.

The Id-proteins are a family of four related proteins implicated in the control of differentiation and cell-cycle progression. Down-regulation of Id-gene expression is essential for the differentiation of several cell types. In addition, deregulated Id2 activity inhibits the Rb tumor suppressor pathway and promotes the expression of vascular endothelial growth factor (VEGF). Several members of VEGF family could be involved in Kaposi's sarcoma (KS) development and progression. Lymphatic vascular endothelial hyaluronan receptor-1 (LYVE-1) is the first marker of lymphatic endothelial competence during development in the mature vasculature, and is also expressed on KS spindle cells. Rapamycin (RAPA), an immunosuppressive drug, has been shown to reverse KS growth and to reduce tumor angiogenesis. We evaluate, in transplantation-associated KS and in cultured KS-cells the RAPA effect on Id2 and on de novo lymphangiogenesis. Markers of lymphatic-endothelial-cells (VEGFR-3, LYVE-1) and Id2, expressed at low levels within the normal skin, were up-regulated in KS and returned to normal levels after RAPA introduction. The association between Id2 and lymphangiogenesis is suggested by co-localization of Id2, VEGFR-3 and LYVE-1. RAPA inhibition on Id2 expression was confirmed in vitro in KS-cells, both in basal conditions and upon stimulation with VEGF. In conclusion, our data would suggest a novel molecular mechanism for the antineoplastic effects of RAPA in posttransplant KS.

Dysfunctional DC subsets in RCC patients: ex vivo correction to yield an effective anti-cancer vaccine.

Dendritic cells (DCs) are potent antigen-presenting cells responsible for the activation and functional polarization of specific T cells. In patients with renal cell carcinoma (RCC) and other cancers, coordinate DC and T cell defects have been reported. In particular, DC and T cell functional subsets that are not conducive to tumor clearance are hypothesized to predominate in patients with advanced-stage disease. Two major peripheral blood DC subsets have been identified in humans: myeloid dendritic cells (mDCs) and plasmacytoid dendritic cells (pDCs) that are believed to mediate contrasting effects on cancer immunity. Given the lack of information regarding DC subsets in patients with RCC, in the present study we have investigated the comparative frequencies and activation states of mDC and pDC in peripheral blood, cancer tissues and lymph nodes of patients with RCC using flow cytometry and immunohistochemistry. Three monoclonal antibodies (mAbs) reactive against specific DC subsets (BDCA-2 or BDCA-4 for pDC and BDCA-1 and BDCA-3 which represent two distinct subsets of mDC, mDC1 and mDC2, respectively) were employed. We observed a significant reduction of both DC subsets in the peripheral blood of patients as compared to normal donors. Similarly, both mDC and pDC were recruited in large numbers into RCC tumor tissues, where they displayed an immature phenotype (DC-LAMP(-)) and appeared unable to differentiate into mature DC (CD83(+)) that were competent to migrate to draining lymph nodes. However, we were readily able to generate ex vivo mDC from RCC patients. These DC stimulated robust anti-tumor CTL in vitro and would be envisioned for use in DC-based vaccines applied in patients with RCC whose existing immune system is judged dysfunctional, anergic or prone to undergo apoptosis.

Ischemia-reperfusion injury-induced abnormal dendritic cell traffic in the transplanted kidney with delayed graft function.

Delayed graft function (DGF) in kidney transplantation is associated with an increased risk of acute rejection. Myeloid dendritic cells (DCs) are involved in graft rejection, whereas plasmacytoid DCs may play a role in inducing tolerance. We evaluated the presence and phenotype of the DCs in renal graft biopsies of 15 patients with DGF collected before and 7-15 days after transplantation. Biopsies taken from normal patients and from transplant recipients with acute calcineurin inhibitors (CNIs) nephrotoxicity served as a control group. Specific markers of myeloid, plasmacytoid, and mature DCs were imaged by confocal microscopy and immunohistochemistry. In normal kidneys and pre-transplant biopsies, sparse niches of myeloid and plasmacytoid cells were found but these were significantly increased with few mature cells during DGF. This same pattern was seen in acute rejection but with overall higher cell numbers. In CNI nephrotoxicity, myeloid cells were slightly increased but plasmacytoid cells were significantly higher than in DGF. Using a pig model, we found that a short period of warm ischemia followed by reperfusion led to myeloid cell infiltration of the kidney. Our data suggest that ischemia-reperfusion injury may cause an imbalance between intragraft myeloid and plasmacytoid DCs, which might be related to DGF and acute rejection.

Analysis of an SD second chromosome from a natural population of Drosophila melanogaster.

The second chromosome Co-122 (Corato-122) extracted from a natural population of Drosophila melanogaster caught in Corato (Apulia) and maintained in the laboratory over the SM5 balancer chromosome, proved to carry: (1) a Segregation distorter factor, named SdCo; (2) a recessive lethal mutation, termed mle-Co (maleless-Corato), which causes the lethality of only males; (3) another recessive lethal mutation, l(2)Co (lethal (2) Corato), probably arisen in the laboratory by mutation. This mutation accounts for the diminished recovery of homozygous females observed in the stock. The genetic features and the cytological analysis of the SD chromosome are reported, as well as the genetic localization of mle-Co and 1(2)Co and their cytogenetic mapping. An allelism test has ascertained that mle-Co is allelic to mle, a male-specific mutation described by Fukunaga et al., 1975. The tight linkage of mle-Co and l(2)Co with Sd is discussed from the standpoint of population genetics.

Biological parameters and the segregation distortion (SD) phenomenon in Drosophila melanogaster.

The relationship between some biological parameters (mortality, longevity, fertility, fecundity and sex ratio) and segregation of second chromosomes in heterozygous and homozygous SD males has been analyzed. The results obtained in SD/SD+ heterozygous males show: (1) their reduced fertility with respect to that of control males, (2) an alteration in the sex ratio in the SD+ progeny only, and (3) inversely related sex-ratio and segregation distortion values. In SDi/SDj combinations: (1) surprisingly, fertility is intermediate between that of SD/SD+ heterozygous males and that of control males, (2) the segregation ratios of the second chromosomes are normal (0.50), and (3) the sex ratio = 0.50 in both classes of SD progeny. The relationship between mortality (and therefore longevity) and fertility of the different genotypes and fecundity per male indicates that the total productivity of heterozygous males is less than that so far claimed. Indeed, their productivity depends not only on the mechanism of nonformation of the SD+ sperm, but also on their reduced longevity. The k = 0.50 and the high fecundity of SDi/SDj combinations indicated that in these males the SD phenomenon is partially suppressed, the SD chromosomes being insensitive to each other, thus implying that particular Rsp alleles are sensitive to given Sd alleles. The complementation pattern for male fertility of SD homozygous males again supports previous evidence that Sd factors from natural populations are, in effect, different Sd genes.

Cytogenetic Analysis of an SD Chromosome from a Natural Population of DROSOPHILA MELANOGASTER.

The discovery and the cytogenetic characterization of a new SD (Segregation Distorter) chromosome 2 from a natural population in Ranna (Sicily, Italy), SD(Ra), are reported. The main features of this chromosome are as follows: (a) it contains an Sd(Ra) gene with a moderate degree of segregation distortion (k = 0.72), (b) a recessive female sterile gene, fs(2)(TLM), responsible for modifications of the morphology and structure of the tests and ovaries is located at 89.7, (c) SD(Ra)/SD(Ra) males and females are viable but sterile, the females due to homozygosis of fs(2)(TLM) and the males because of homozygosis of a region containing the Sd locus, and (d) SDi/SDj combinations are fertile, thus suggesting that the different Sd factors found in natural populations constitute a multiple allelic series.-These data may indicate that each population containing SD chromosomes has evolved its own genetic architecture for the complex SD system, with specific modifiers and perhaps different Sd genes. The possibility of reconstructing the evolutionary pattern of the SD(Ra) chromosome in the natural Ranna population after the model of Charlesworth and Hartl (1978) and Crow (1979) is considered.