Christian Denecke

Harvard Medical School, Boston, Massachusetts, United States

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Publications (22)75.86 Total impact

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    ABSTRACT: Stasis of the flow of the intestinal contents, ingested material and unfavorable composition of the chylus can lead to the formation of enteroliths inside the bowel. Enterolithiasis represents a rare disorder of the gastrointestinal tract that can be associated with intermittent abdominal pain or more serious complications such as bleeding or obstruction. Enterolithiasis in Crohn's disease represents an extremely rare condition and usually occurs only in patients with a long symptomatic history of Crohn's disease. We report an unusual case of enterolithiasis-related intestinal obstruction in a young male patient with Crohn's disease (A2L3B1 Montreal Classification for Crohn's disease 2005) undergoing emergency laparotomy and ileocoecal resection. In addition, we present an overview of the relevant characteristics of enterolithiasis on the basis of the corresponding literature.
    World Journal of Gastroenterology 11/2012; 18(42):6160-3. · 2.55 Impact Factor
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    ABSTRACT: BACKGROUND: Organs from DCD (donation after cardiac death) donors are increasingly used for transplantation. The impact of advanced donor age and warm ischemia on the immune response of the recipient has not been studied. We developed a novel and clinically relevant model of DCD kidney transplantation and investigated the effects of donor age and prolonged warm ischemia on the recipient immune response after following DCD kidney transplantation. METHODS: DCD grafts from young and old F-344 donor rats were engrafted into LEW recipients who were nephrectomized bilaterally after a short (20 minutes) or prolonged (45 minutes) warm ischemia time. RESULTS: Analysis of the recipient's immune response early after transplantation showed an enhanced innate and adaptive immune response when old DCD kidneys were engrafted. Next, we studied DCD recipients with a supportive, contralateral native kidney in place, which allowed the recovery of the transplanted DCD kidney. Old DCD kidneys, demonstrated an impaired renal function associated with pronounced histomorphologic graft deterioration and an enhanced immune response by day 100 after transplantation. Interestingly, young DCD kidneys with a long warm ischemic time recovered from acute tubular necrosis and did not stimulate the long-term immune response. CONCLUSION: Our observations emphasize that prolonged warm ischemic time and advanced donor age augment the immune response after transplantation of DCD grafts. These results provide an experimental model and a mechanistic framework of clinically relevant aspects in DCD donation.
    Surgery 10/2012; · 3.37 Impact Factor
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    ABSTRACT: Tolerance induction protocols have been successfully tested in animal models, yet their compatibility with immunosuppressive drugs remains to be fully elucidated. Our own previous data have indicated that cyclosporine A (CsA) affects the balance of effector and regulatory mechanisms with low-dose CsA doses promoting hyporesponsiveness. Here, we present a fully mismatched rat kidney model in which low-dose CsA treatment induces donor hyporesponsiveness to secondary renal allografts. Lewis recipients of DA kidney grafts received low, medium or high doses of CsA × 10 days. By 30 days, the primary transplant was removed and a second transplant of donor origin was engrafted. Following low-dose CsA, but not high-dose CsA treatment of the primary recipient, secondary transplants were accepted long-term in the absence of immunosuppression. Regulatory T-cell function was unimpaired and independent of the CyA dosage. Of note, low-dose CsA significantly reduced alloantibody titers in primary recipients. Adoptive transfer of graft infiltrating cells or splenocytes from hyporesponsive recipients supported long-term acceptance of donor kidney allografts. These results demonstrate a dose-dependent and transferable "pro-tolerogenic" effect of low-dose CsA treatment. This model is of clinical relevance to test the interference of CsA with tolerance induction in the absence of additional immunosuppression.
    Transplant Immunology 03/2012; 26(4):176-85. · 1.52 Impact Factor
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    ABSTRACT: With an increasing demand, organs from elderly donors are more frequently utilized for transplantation. Herein, we analyzed the impact of donor age on CD4(+) T-cell responses with regard to regulatory and effector mechanisms. Young (3months) BM12 recipients were engrafted with young or old (18months) B6 cardiac allografts. Systemic CD4(+) T-cell responses and intragraft changes were monitored and compared to age-matched syngenic transplant controls. While elderly, nonmanipulated hearts contained significantly elevated frequencies of donor-derived leukocytes prior to transplantation, allograft survival was age-independent. T-cell activation, however, was delayed and associated with a compromised immune response in mixed lymphocyte cultures (MLR; P=0.0002) early after transplantation (day 14). During the time course after transplantation, recipients of old grafts demonstrated an augmented immune response as shown by significantly higher frequencies of activated CD4(+) T-cells and a stronger in vitro alloreactivity (MLR; ELISPOT; P<0.01). In parallel, frequencies of regulatory T-cells had increased systemically and overall fewer CD4(+) T-cells were detected intragraft. Interestingly, changes in the CD4(+) T-cell response were not reflected by graft morphology. Of note, transplantation of young and old syngenic hearts did not show age-related differences of the CD4(+) T-cells response suggesting that old grafts can recover from a period of short cold ischemia time. Our data suggest that donor age is associated with an augmented CD4(+) T-cells response which did not affect graft survival in our model. These findings contribute to a better understanding of the immune response following the engraftment of older donor organs.
    Transplant International 12/2011; 25(3):328-36. · 3.16 Impact Factor
  • Christian Denecke, Stefan G Tullius
    Transplant International 09/2011; 24(9):880-1. · 3.16 Impact Factor
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    ABSTRACT: Elderly organ transplant recipients represent a fast growing segment of patients on the waiting list. We examined age-dependent CD4(+) T-cell functions in a wild-type (WT) and a transgenic mouse transplant model and analyzed the suppressive function of old regulatory T-cells. We found that splenocytes of naïve old B6 mice contained significantly higher frequencies of T-cells with an effector/memory phenotype (CD4(+)CD44(high)CD62L(low)). However, in-vitro proliferation (MLR) and IFNgamma-production (ELISPOT) were markedly reduced with increasing age. Likewise, skin graft rejection was significantly delayed in older recipients and fewer graft infiltrating CD4(+)T-cells were observed. Old CD4(+) T-cells demonstrated a significant impaired responsiveness as indicated by diminished proliferation and activation. In contrast, old alloantigen-specific CD4(+)CD25(+)FoxP3(+) T-cells demonstrated a dose-dependent well-preserved suppressor function. Next, we examined characteristics of 18-month old alloreactive T-cells in a transgenic adoptive transfer model. Adoptively transferred old T-cells proliferated significantly less in response to antigen. Skin graft rejection was significantly delayed in older recipients, and graft infiltrating cells were reduced. In summary, advanced recipient age was associated with delayed acute rejection and impaired CD4(+) T-cell function and proliferation while CD4(+)CD25(+)FoxP3(+) T-cells (Tregs) showed a well-preserved function.
    PLoS ONE 01/2010; 5(2):e9232. · 3.73 Impact Factor
  • Transplantation 01/2010; 90. · 3.78 Impact Factor
  • Transplantation 01/2010; 90. · 3.78 Impact Factor
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    ABSTRACT: The increasing age of organ donors and the transplantation of older recipients have become clinical practice. Age-adapted immunosuppressive protocols considering these changes are currently not established. This study analyzed the age-dependent immune response after human kidney transplantation. One hundred renal allograft recipients were prospectively evaluated from 2004 to 2005. Patients older than 65 years of the European Senior Program receiving kidneys from donors older than 65 years were compared with recipients younger than 65 years receiving kidneys from donors younger than 65 years. Age-dependent modifications of the immune response were evaluated before transplantation and 7 days and 6 months after grafting by flow cytometry analysis of lymphocyte surface markers in peripheral blood. The cytokine pattern was determined by Cytometric Bead Array, T-cell alloreactivity by enzyme-linked immunospot analysis. There were no differences between the groups regarding patient survival, graft survival, and function at 6 months after transplantation. Before transplantation, 7 days and 6 months thereafter recipients older than 65 years demonstrated significantly elevated numbers of memory T-cells while counts for naive T-cells were significantly reduced. Numbers of activated cytotoxic cells were elevated with increasing age before and 7 days after transplantation. T-cell alloreactivity was more pronounced in older recipients at all time points. Seven days after transplantation tumor necrosis factor-alpha (TNF-alpha) levels were significantly higher, whereas TNF-alpha and interleukin-10 (IL-10) concentrations were significantly reduced after 6 months in older recipients. Our data demonstrate an initially pronounced immune response in elderly recipients receiving grafts from elderly donors. This observation supports the concept of a donor and recipient age-adapted immunosuppression.
    Transplantation 05/2009; 87(7):992-1000. · 3.78 Impact Factor
  • Journal of The American College of Surgeons - J AMER COLL SURGEONS. 01/2009; 209(3).
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    ABSTRACT: Until recently, research on transplantation rejection and tolerance has been directed toward deciphering the mechanisms of the adaptive immune system. However, the emergence that the innate immune system, the body's first-line defense against pathogens, has a strong influence on adaptive immunity has galvanized interest in elucidating the interplay between these two arms of the immune system. The discovery of Toll-like receptors and the characterization of the cellular mediators involved in innate immunity have provided growing evidence that innate immunity affects the adaptive immune response. Emerging evidence has also shown that early "danger signals"' associated with ischemia-reperfusion injury or brain death contribute to innate immune activation, promoting rejection, and inhibiting tolerance induction. In addition, nonspecific stimuli such as increased donor age or patient disease may also serve to exert a synergistic influence on innate immune activation. Ultimately, controlling the events in innate immune activation may help drive tolerance induction and reduce the rate of rejection.
    Transplantation 11/2008; 86(7):889-94. · 3.78 Impact Factor
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    ABSTRACT: The precise role that CD8+ T cells play in the rejection and acceptance of different types of allograft is unclear and has been shown to vary between donor-recipient combinations. The response of adoptively transferred CD8+ T cells reactive to the donor alloantigen H2Kb was examined after transplantation of H2Kb liver, kidney, and heart grafts in mice. After transfer of 6 x 10(6) alloreactive CD8+ T cells to T-cell depleted syngeneic mice spontaneous long-term acceptance of liver grafts was observed, whereas kidney and heart grafts were acutely rejected. Within 5 days of liver transplantation, we found that the entire H2Kb-reactive T-cell pool was stimulated to proliferate and differentiate into memory or effector cells that were detectable within lymphoid tissues as well as the liver graft itself. However, despite the generation of effector or memory T cells, liver allografts were accepted, which correlated with the exhaustion or deletion of such cells. In contrast, although activation and proliferation of H2Kb-reactive CD8+ T cells was observed after transplantation of heart or kidney grafts, unactivated, H2Kb-reactive CD8+ T cells were still present in the spleen even long term. Interestingly, differences in the effector function of liver and kidney graft infiltrating donor-reactive CD8+ T cells were not detected after adoptive transfer into immunodeficient mice, despite a reduction in Th1-type cytokines within liver grafts. The rapid and extensive initial activation and differentiation of donor-reactive CD8+ T cells that occurs after liver transplantation leads to clonal exhaustion or deletion of the alloreactive CD8+ T-cell repertoire resulting in spontaneous tolerance induction.
    Transplantation 06/2008; 85(9):1339-47. · 3.78 Impact Factor
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    ABSTRACT: Ischemic preconditioning directly protects organs from subsequent non-specific injuries. To test for systemic protective effects kidneys from F-344 donor rats went through a short warm ischemic time. Both, clamped and contralateral unclamped kidneys were procured after either a short (15 min) or long (24 h) reperfusion period and transplanted into Lewis rats following a prolonged cold ischemia. To test for transferable effects serum from preconditioned rats was infused either into native donors or recipients. Following a short reperfusion interval protective effects were only evident in previously clamped grafts. However, after a long reperfusion interval protective effects were observed in previously clamped and contralateral unclamped kidneys promoting improved survival, structure, function and reduced inflammation. These effects were not related to heme oxygenase-1 induction or neural transmission as heme oxygenase-1 inhibition or denervation prior to preconditioning did not affect organ protection. These results show that renal ischemic preconditioning is associated with time-dependent local and systemically transferable protection.
    Kidney International 06/2008; 74(5):622-30. · 7.92 Impact Factor
  • Transplantation 01/2008; 86:489-490. · 3.78 Impact Factor
  • Transplantation 01/2008; 86. · 3.78 Impact Factor
  • Transplantation 01/2008; 86. · 3.78 Impact Factor
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    ABSTRACT: Increasing donor age is associated with reduced graft function. We wondered if donor age may not only affect intrinsic function but also alter the immune response of the recipient. Kidneys from young and old F-344 rats (3 vs 18 months) were transplanted into bilaterally nephrectomized young Lewis recipients and compared with age-matched controls (follow-up: 6 months). Renal function and structural changes were assessed serially in both native kidneys and allografts. Host alloreactivity, graft-infiltrating cells, and their inflammatory products were determined at intervals to examine the correlation of immune response and donor age. Functional and structural deterioration had advanced significantly in older allografts compared with age-matched native controls, whereas differences between young allografts and native controls of similar age were only minor. Changes in grafts from elderly rats were associated with a more intense host immune response early post-transplant (up to 1 month) reflected by significantly higher numbers of peripheral T and B cells, increased T-cell alloreactivity and modified cytokine patterns associated with elevated frequencies of intragraft dendritic cells, B cells, and CD31+ cells. By 6 months, recipients of young donor grafts produced comparable or more intense alloantigen-specific immune responses. Older donor grafts elicit a stronger immune response in the early period after transplantation.
    Kidney International 05/2007; 71(7):629-36. · 7.92 Impact Factor
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    ABSTRACT: Nonspecific inflammatory damages occurring prior to organ transplantation reduce long-term graft survival. Here, we tested the beneficial effects of carbon monoxide (CO) induction by methylene chloride (MC). Fischer-344 (F-344 Rat) or Dark Agouti (DA Rat) donor animals were either treated with MC four hours prior to organ removal or remained untreated. Kidneys were transplanted into Lewis (LEW) recipients. The low responder strain combination (F-344-->LEW) was studied for long-term graft changes. Dendritic cells (DCs) migration and early changes were followed in additional groups of a high responding donor/recipient strain combination (DA-->LEW). Native kidneys of uninephrectomized, age-matched normal animals served as controls. Following MC application COHb peaked within two hours in donor animals. Renal function and morphology improved significantly in renal allografts of CO induced donor animals and were comparable to native controls long-term (24 wks). Early after transplantation (24 hr) donor-derived DCs, CD4+ T-cells and alloreactive T-cells were significantly reduced following the engraftment of organs from treated donors. In addition, a trend towards a Th1/Th2 shift and a significant intragraft reduction of CD3 mRNA expression was observed. Donor treatment for the induction of CO reduced graft immunogenicity and inhibited chronic allograft nephropathy.
    Transplantation 11/2006; 82(7):938-44. · 3.78 Impact Factor
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    ABSTRACT: Organ shortage and increasing numbers of older patients on the waiting list represent major challenges in organ transplantation. As a consequence, older donor organs are increasingly used and preferentially allocated to elderly recipients. However, knowledge on donor age– and recipient age–dependent immune responses is limited. We reviewed the impact of donor age and recipient age on clinical outcomes. An increased immunogenicity of older grafts and an altered immune response of elderly recipients may require age-specific immunosuppression. Age-related immune responses may also impact current preclinical tolerance protocols.
    Transplantation Reviews. 01/2006; 20(4):179-188.
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    ABSTRACT: With a growing demand for transplants, grafts from older donors are increasingly used. However, altered immune responses associated with increasing donor age may influence graft survival. We dissected the effects of donor age on the immune response in an experimental model. Kidneys from young and old F-344 donors (3 and 18 months) transplanted into young Lewis recipients (3 months) were followed for 6 months. Renal function, structural changes, and immune activation were tested at serial time intervals. Splenocytes and peripheral blood mononuclear cells were examined by flow cytometry; alloantigen-specific intracellular IFN-gamma secretion was evaluated by ELISPOT. Grafts from both young and old donors survived the observation period. The ratio of structural changes (6/1 months) increased twofold in old vs young grafts. In parallel, the ratio of renal function declined by fivefold in recipients of old donor kidneys. Most interestingly, elderly grafts produced a modified immune response: the numbers of T/B cells and alloreactive T cells increased early following the transplantation of old grafts (P < .05). However, by 6 months, the amounts of T and B cells as well as alloantigen-specific immune responses were comparable in recipients of old versus young grafts. Older grafts elicit a stronger immune response during the early period posttransplantation. This process is associated with an increased immunogenicity in older grafts. Clinical immunosuppressive protocols need to consider these effects.
    Transplantation Proceedings 01/2005; 37(1):382-3. · 0.95 Impact Factor

Publication Stats

120 Citations
25 Downloads
892 Views
75.86 Total Impact Points

Institutions

  • 2012
    • Harvard Medical School
      Boston, Massachusetts, United States
  • 2006–2011
    • Brigham and Women's Hospital
      • • Transplantation Research Center
      • • Department of Medicine
      Boston, MA, United States
  • 2007–2009
    • Charité Universitätsmedizin Berlin
      • Department of General, Visceral and Transplantation Surgery
      Berlín, Berlin, Germany