Interleukin-10 fails to modulate low shear stress-induced neointimal hyperplasia.

INTRODUCTION: Overexpression of the anti-inflammatory cytokine interleukin-10 (IL-10) blocks atherosclerotic events in vivo, and IL-10 has been recently hailed as an "immunologic scalpel" for atherosclerosis. Alternatively, mice lacking IL-10 receiving atherogenic diets have increased occlusive lesions. It remains unclear whether such IL-10 modulation broadly applies to other forms of occlusive arterial remodeling. We hypothesized that lack of IL-10 would exacerbate, and exogenous or overexpression of IL-10 would abrogate low shear stress-induced neointimal hyperplasia (NIH). METHODS: Wild-type (WT) and IL-10-deficient (IL-10-/-) mice underwent unilateral common carotid artery (CCA) ligation. Low shear stress in the patent ligated artery results in remodeling and formation of neointima containing BrdU and SMC alpha-actin-positive cells. Additional groups of WT mice underwent CCA ligation and were treated daily with intraperitoneal saline or 1 microg of human IL-10. Chronic delivery gene therapy approaches were also utilized to define the role of IL-10 signaling. WT mice were treated adventitially with 1 x 10(10) adenovirus/green fluorescent protein (Ad/gfp) and an Ad/empty control to confirm the veracity of adventitial delivery. Then, Ad viral IL-10 (vIL-10), Ad/empty, and virus buffer alone were applied directly to the adventitia of the CAA immediately following ligation. In separate experiments, 1 x 10(10) Ad/empty or Ad/vIL-10 was injected intramuscularly. CCAs were perfusion fixed 28 days postligation, the time at which NIH is near maximum. RESULTS: IL-10-/- mice developed identical NIH areas compared to WT controls. Mice receiving IL-10 demonstrated NIH equivalent to saline controls. Mice receiving intramuscular or adventitial Ad/IL-10 developed high serum levels of IL-10 yet formed NIH areas similar to those of controls. Serum IL-10 levels were significantly higher (P = 0.04) with adventitial delivery. Mice treated adventitially with Ad/gfp showed reliable transfection of cells within the adventitia of CAA. No antibody to human IL-10 was found in the sera of intraperitoneal IL-10-treated mice, which failed to attenuate NIH. CONCLUSION: Under the conditions of this experiment, lack of IL-10 does not exacerbate low shear stress-induced NIH, nor does exogenous administration or overexpression of IL-10 attenuate it. Despite high serum levels of vIL-10 in mice treated with ad/vIL-10 adventitially, there appears to be no therapeutic effect despite the confirmed transfection of adventitial cells. Discrepancies between these findings and previous research may be related to IL-10 dosing, inflammation induced by the adenoviral vector, or disparities between the NIH models.     

CD1-dependent natural killer (NK1.1(+)) T cells are required for oral and portal venous tolerance induction

BACKGROUND: Local antigen presentation via either the oral (PO) or the portal venous (PV) routes results in suppression of systemic delayed-type hypersensitivity (DTH). The responsible cell populations are not well defined. Because NK1.1(+) T cells express the Fas ligand and produce high levels of the immunosuppressive cytokine, IL-4, they may play a role in both activated T-cell apoptosis and a Th1 to Th2 immune shift, thus promoting tolerance induction. METHODS: C57BL/6 mice were tolerized to BALB/c alloantigen by PV or PO spleen cells (25 x 10(6)) on Day 0. Subcutaneous (SQ) challenge with 10 x 10(6) BALB/c cells on Day 7 was followed by footpad injection of 10 x 10(6) BALB/c cells on Day 14. Footpad swelling was measured 24 h later. A single injection of the NK1.1(+) cell-depleting antibody, PK-136, was given IP (10 mg/kg) 2 days prior to PV or PO antigen. Flow cytometry evaluated NK1.1(+) cell depletion. CD1 knockout (KO) mice, lacking NK1.1(+) T cells, were also challenged with PV and PO Balb/c in parallel experiments. RESULTS: The DTH to BALB/c antigen was markedly suppressed in C57BL/6 mice when this alloantigen was given by either PO or PV routes (P < 0.001, P < 0.001). The maintenance of an unaltered response to third-party C3H/HeJ demonstrated alloantigenic specificity. Administration of the anti-NK1.1 T cell monoclonal antibody, PK-136, resulted in complete restoration of in vivo DTH responsiveness in PO tolerance (P < 0.01), and partial restoration in PV tolerance (P < 0.05) in C57BL/6 mice. FACS confirmed virtually complete depletion of liver, splenic, Peyer's patch, and mesenteric lymph node NK1.1(+) lymphocytes. Development of both PO and PV tolerance was prevented in CD1 KO mice. CONCLUSION: NK1.1(+) T cells play an essential role in antigen-specific suppression of the DTH response mediated by both oral and portal venous tolerance.     

Transfer of "infectious" cardiac allograft tolerance induced by donor-specific transfusion

BACKGROUND: "Infectious tolerance" has been defined as the tolerance induced in a new recipient by the adoptive transfer of cells from a recipient accepting an allograft after anti-CD4 and anti-CD8 monoclonal antibody treatment. A clear understanding of the mechanisms responsible for graft acceptance after donor-specific blood transfusion (DST) has remained elusive. We examined the development and "infectious" nature of immunologic changes resulting in indefinite survival of LEW to DA rat cardiac allografts after DST alone without the need for antibody. METHODS: One hundred x 10(6) LEW splenocytes (SC) as DST were injected intravenously into DA recipients 7 days before LEW cardiac transplantation. Subsequently, 100 x 10(6) SC harvested from a DA recipient 30, 60, or 100 days after graft acceptance were adoptively transferred into lightly gamma-irradiated (450 rad) na?ve DA recipients 24 hours before a second LEW cardiac allograft. Subsequent graft function was determined. RESULTS: Adoptive transfer of SC from the DST-treated DA rats 30 days after LEW heart transplant acceptance into na?ve gamma-irradiated DA rats failed to transfer tolerance to LEW cardiac allografts. However, SC from DA rats bearing LEW hearts for more than 60 days induced indefinite tolerance to all LEW hearts. This infectious tolerance could be adoptively transferred again to a second DA recipient. CONCLUSIONS: DST-generated regulatory cells can downregulate na?ve lymphocytes to promote allograft acceptance. This tolerance can be expanded and serially transferred to a subsequent na?ve cardiac recipient.     

Vascular complications associated with pancreaticoduodenectomy adversely affect clinical outcome

BACKGROUND: Early survival after pancreaticoduodenectomy has improved, but its morbidity remains high. The purpose of this study is to determine how the intra-operative (OR) occurrence of major vascular complications affects the outcome of pancreaticoduodenectomy. METHODS:The medical records of 180 consecutive patients having pancreaticoduodenectomy from 1991 to 2001 were reviewed. Vascular complications were defined as "an unanticipated injury or thrombosis of a major vessel necessitating intervention." Age, sex, type of pancreaticoduodenectomy, tumor size, estimated blood loss, OR time, time in intensive care, post-OR hospitalization, and survival were compared. RESULTS: Eighteen vascular complications were identified. Differences in age, sex, and type of resection between patients with or without vascular complications were not significant. OR time, estimated blood loss, blood transfusions, tumor size, time in intensive care, and post-OR hospitalization were all significantly greater in patients with vascular complications. Median survival for patients with vascular complications was significantly shorter than for patients without vascular complications. Thirty-day mortality was greater in patients with vascular complications. CONCLUSION: Vascular complications significantly affect the outcome of pancreaticoduodenectomy increasing OR time, estimated blood loss, blood transfusion requirements, time in intensive care, post-OR hospitalization, and mortality.     

Cadaveric-donor organ recovery at a hospital-independent facility

BACKGROUND: Of the many logistic issues addressed throughout the cadaveric organ donation process, timely access to the operating theater for surgical recovery of organs and tissues can be one of the most problematic. Delay in recovery adds to cost, risks organ viability, and compounds donor family anguish with compromise to donation consent. METHODS: From March 1 to November 30, 2001, 25 cadaveric donors were selected and successfully transferred from local donor critical care units to an off-site facility, which was constructed, equipped, and staffed to allow surgical recovery of organs and tissues. Assessment of the recovery process and outcome results was compared to 42 consecutive, hospital-based, organ recoveries within the Mid-American Transplant Services (MTS) organ procurement organization region. RESULTS: Twenty-five MTS-facility and 42 hospital organ recoveries were successfully conducted with no technical losses and satisfactory function in all 206 transplanted organs. From the MTS donor group, 7 hearts, 4 lungs, 21 livers, 28 kidneys, and 5 pancreases were successfully transplanted. Statistically significant in the MTS group was higher donor age (44.1 vs. 30.2 years), shorter total donor management time (539 vs. 718 min), reduced delay in start of surgery (25 vs. 77 min), shorter cold ischemia time for recovered pancreases (355 vs. 630 min), and reduced mean cost per donor ($10,636 vs. $12,918). There was no significant difference in race, gender, cause of death, vasopressor requirements, organs per donor recovered (3.12 vs. 3.62) or transplanted (2.60 vs. 3.36), rate of tissue recoveries (68% vs. 67%), total operating room time (207 vs. 200 min.), or cold ischemia time (excluding pancreas). CONCLUSIONS: Cadaveric-donor multiorgan and tissue recovery at this hospital-independent facility was successfully accomplished in a manner indistinguishable from conventional hospital organ and tissue recovery. The intended objectives of improved access to the operating theater were realized along with the added benefit of significant cost savings and convenience to hospital personnel and surgical recovery teams.     

Lipoteichoic acid from Staphylococcus aureus reduces renal ischemia/reperfusion injury

BACKGROUND: The aim of this study was to investigate whether in vivo administration of a low, sub-lethal dose of lipoteichoic acid (LTA), a bacterial wall-fragment derived from the Gram-positive bacterium Staphylococcus aureus, protects the kidney against the renal dysfunction and injury caused by ischemia/reperfusion (I/R). METHODS: Male Wistar rats were administered LTA from S. aureus (1 mg/kg, IP). After 24 hours, rats were subjected to bilateral renal ischemia (45 min) followed by reperfusion (6 h). Serum and urinary markers were measured for the assessment of renal function, tubular and reperfusion-injury. Renal sections were used for histological grading of renal injury and for immunohistochemical localization of P-selectin, inducible nitric oxide synthase (iNOS) and nitrotyrosine (indicative of peroxynitrite formation). Kidney myeloperoxidase (MPO) activity and malondialdehyde (MDA) levels were measured for assessment of polymorphonuclear (PMN) cell infiltration and lipid peroxidation, respectively. Nitric oxide (NO) production was determined by measurement of plasma nitrite/nitrate levels. RESULTS: LTA pretreatment significantly reduced renal dysfunction, tubular and reperfusion-injury caused by I/R of the kidney as well as histological evidence of renal injury. LTA also reduced the expression of P-selectin and kidney MPO activity associated with renal I/R. MDA levels were significantly reduced by LTA pretreatment suggesting a reduction in the lipid peroxidation and formation of reactive oxygen species (ROS). LTA pretreatment also markedly reduced both the expression of iNOS and the formation of nitrotyrosine associated with renal I/R. Although LTA significantly reduced plasma nitrite/nitrate levels associated with I/R, nitrite/nitrate levels remained at levels significantly higher than that measured from the plasma obtained from Sham-operated animals. CONCLUSIONS: These data suggest, to our knowledge for the first time, that LTA pretreatment for 24 hours significantly reduces renal I/R injury. We propose that the mechanism of the protective effect involves reduction of the production of NO, ROS and peroxynitrite subsequent to reduced P-selectin and iNOS expression and PMN recruitment. However, although LTA pretreatment resulted in a reduction of iNOS expression and NO production, we hypothesize that the remaining significant levels of NO contribute to the beneficial actions provided by LTA.