Search PubMed⌕ Search

Biomedical subjects

F Sanfilippo

Publications and source records attributed to F Sanfilippo.

At least 19 recordsLinked to original sources
PubMed1998

Prolonged discordant xenograft survival by inhibition of the intrinsic coagulation pathway in complement C6-deficient recipients.

BACKGROUND: Xenotransplantation of vascularized organs between unmodified discordant species results in hyperacute graft rejection within minutes to hours after graft reperfusion. This process is due to the presence of natural xenoreactive antibodies and complement activation, which lead to vessel injury, thrombosis, and hemorrhage. Because multiple components of the coagulation and complement cascades interact with each other, we have investigated the effects of inhibiting these systems together. The recombinant Kunitz type serine protease inhibitor (KPI-BG022) tested in these experiments inhibits factor XIIa, kallikrein, and plasmin. METHODS: Cardiac xenografts from male Hartley guinea pigs were heterotopically grafted into male PVG rats that were either sufficient (C6[+]) or deficient (C6[-]) for the complement component C6 and thus formation of the membrane attack complex. Experimental animals received KPI 5 mg/kg intravenously before reperfusion, and control animals received saline placebo. RESULTS: C6(+) recipients rejected their grafts hyperacutely, without a significant difference between KPI-treated (0.12+/-0.05 hours) and placebo-treated (0.13+/-0.06 hours) recipients (n = 10). As expected, C6(-) recipients showed prolonged graft survival (17.65+/-3.45 hours, n = 5). However, a single intravenous bolus of KPI before releasing the clamps further delayed graft rejection in C6(-) recipients (46.2+/-3.3 hours; n = 5). Histologic examination at 2, 6, and 12 hours after transplantation showed platelet aggregation and inflammatory infiltrates were significantly decreased in KPI-treated (C6[-]) recipients. However, intragraft hemorrhage was apparent at 6 and 12 hours. CONCLUSIONS: We conclude that in vivo inhibition of the intrinsic clotting cascade by functional inactivation of factor XIIa has a synergistic effect with inhibition of membrane attack complex formation in preventing hyperacute discordant xenograft rejection.

Animals↗
PubMed1998

Complement contributes to the rejection of complete and class I major histocompatibility complex--incompatible cardiac allografts.

BACKGROUND: We have demonstrated previously that the terminal complement component C6 contributes to the acute rejection of ACI cardiac allografts by PVG recipients. ACI rats differ from PVG rats at major and minor histocompatibility antigens and ACI cardiac allografts stimulate vigorous alloantibody responses in PVG rats. We have now bred the C6 deficiency onto four PVG congenic rat strains to determine the effects of C6 on cardiac allograft survival across individual donor-recipient major histocompatibility complex (MHC) disparities. METHODS: Hearts from C6-deficient PVG.1A (RT1a) donors were transplanted heterotopically to fully MHC-incompatible C6-sufficient and C6-deficient PVG.1L (RT1(1)) recipients, as well as from C6-deficient PVG.R8 (RT1.AaBu) donors to MHC class I incompatible C6-sufficient and C6-deficient PVG. 1U (RT1.AuBu) recipients. RESULTS: Hearts from PVG.1A (C6-) female donors were rejected acutely (7 to 9 days; n = 5) by fully MHC disparate female PVG.1L (C6+) recipients, but they survived significantly longer in female PVG.1L (C6-) recipients (13 to >50 days; n = 6). Slightly better survival resulted in male PVG.1L (C6-) heart transplant recipients of male PVG.1A (C6-) hearts (19 to >50 days [n = 5] vs 6 to 9 days for C6+ male PVG.1L recipients [n = 10]). The C6 deficiency had an even greater effect in PVG.1U recipients of class I MHC disparate PVG.R8 hearts (>50 day survival in C6- PVG.1U recipients [n = 5] vs 6 to 7 days in C6+ recipients [n = 8]). The cardiac allografts elicited similarly vigorous immunoglobulin M and G alloantibody responses in the C6- and C6+ recipients as measured by flow cytometry. At the time of acute rejection, the hearts in the C6+ recipients demonstrated extensive vascular endothelial destruction. In contrast, rejection of hearts by C6- recipients was characterized by endothelialitis, but there was little destruction of the endothelium and limited proliferation of smooth muscle cells in the intima. CONCLUSIONS: These results demonstrate that the terminal complement component C6 can contribute to the rejection of class I or complete MHC-incompatible hearts in rats that have been characterized as "high" alloantibody responders.

Animals↗
PubMed1997

Effect of continuous complement inhibition using soluble complement receptor type 1 on survival of pig-to-primate cardiac xenografts.

A single bolus of soluble complement (C) receptor type 1 (sCR1, TP-10) has been shown to delay hyperacute rejection (HAR) of porcine cardiac xenografts (Xgs) by primate recipients. In these recipients, C activity slowly returned and C deposition was noted in the Xgs at rejection. To evaluate the effect of sustained C inhibition using sCR1 on HAR, two additional cynomolgus monkeys received porcine cardiac Xgs and a continuous infusion of sCR1. In the first recipient, Xgs survival was 5 days (120+ hr), whereas in the second, Xg survival was 7 days (168+ hr). Serial biopsies of the Xgs were remarkable for an increasing cellular infiltrate composed predominantly of neutrophils and macrophages, and the development of edema, hemorrhage, and myocyte necrosis. These findings suggest that once C-mediated HAR has been inhibited, infiltration of the Xg by these cells may lead to accelerated acute rejection, which is an additional barrier to successful longer term Xg survival.

Animals↗
PubMed1997

Delayed graft function: immediate and late impact.

Delayed graft function remains a frequent problem after renal transplantation, which is often associated with subsequent graft failure. The major risks for delayed graft function are incurred during organ procurement, preservation, and transplantation, and are predominated by ischemic injury. The cofactors associated with delayed graft function that lead to subsequent poor outcome include early acute rejection as well as immunologic risk factors for rejection, such as presensitization, human leukocyte antigen mismatch, and previous loss of graft. Numerous diagnostic and therapeutic approaches have been assessed in recent years, but predicting or modifying adverse outcomes associated with delayed graft function in a given patient remains unreliable.

Graft Rejection↗
PubMed1997

The role of CD11b/CD18 mediated neutrophil adhesion in complement deficient xenograft recipients.

Hyperacute rejection (HAR) of discordant xenografts is dependent on local complement activation. The formation of a functional complex of the complement components C5b-9 (membrane attack complex, MAC) causes endothelial injury and activation leading to coagulation and inflammation. In PVG rats which selectively lack the C6 component of complement, the MAC complex is not formed, whereas early split products of the complement cascade are produced normally. We reported previously that HAR is averted in C6 deficient xenograft recipients, and that subsequent accelerated acute rejection (AAR) can be delayed by inhibition of CD11b/CD18 (Mac-1) dependent neutrophil adhesion using leumedin, a member of a novel class of anti-inflammatory agents. Here we report the in vivo effects of a dose-response study using 2 new members of another class of Mac-1 directed agents designated nactins. Discordant cardiac xenografts from Hartley guinea pigs were heterotopically grafted into PVG(C6-) and PVG(C6+) rats. Experimental animals were divided into 3 groups receiving leumedin (group 1) or nactin (groups 2 and 3). Control animals received intravenous saline solution only. All C6(+) rats rejected their grafts hyperacutely within 10 to 15 min, irrespective of mode or dosage of treatment. C6 deficient controls rejected grafts within 17.7 +/- 3.5 h (n = 10). Treatment with leumedin/nactin prolonged graft survival up to 61.0 +/- 4.7 h (n = 4-6), with dose dependent differences in effectiveness among the 3 compounds tested. Histology showed that treatment was associated with less edema, hemorrhage, and neutrophil infiltrate at 2, 6, and 12 h. The marked decrease in hemorrhage seen in nactin-treated animals may reflect an interaction of Mac-1 with blood coagulation factors. Our data confirm that the neutrophil adhesion pathway is involved in AAR, especially when complement mediated injury due to MAC is restricted.

Acute Disease↗
PubMed1997

Morphostructural relationships between bone and implant: comparative analyses by optical microscopy and microradiography.

This study assessed the relationship between the surfaces of a hollow cylindrical titanium implant and the consequent bone organization around it. A human bone maxillary specimen was taken that enclosed an implant which had lasted 28 months under prosthetic loading. The implant was removed because of fracture that prevented the implant from being used as a supporting element for new prosthetic aims. The bone block-section was fixed and embedded, several sections were obtained, and each section was analyzed using three different histologic analyses: optical microscopy under ordinary light and polarized light, and microradiography. Comparative analyses were required on every single section to provide a complete morphostructural analysis of the peri-implant bone. Data retrieved by this research showed the presence of woven bone in the bone layer facing the external implant surface several months after its surgical fitting and functionalization. This finding demonstrates the importance of woven bone, first as holding sheath in the immediate postsurgical stage, and second as a mold for the subsequent centripetal accrementition of secondary lamellar bone.

Dental Implantation, Endosseous↗
PubMed1996

CTLA4Ig inhibits alloantibody responses to repeated blood transfusions.

Allosensitization is a fundamental problem that limits the effectiveness of blood transfusions. Patients who receive multiple transfusions of blood or blood components frequently develop alloantibodies against donor alloantigens. Allosensitized patients are refractory to further transfusion and difficult to transplant successfully. CTLA4Ig fusion protein, which blocks the CD28-B7 costimulatory pathway in T-lymphocyte activation, was tested for its capacity to inhibit allosensitization to blood transfusions. Groups of LEW (RT1') rats were transfused with ACI blood (RT1a) together with L6 (a human immunoglobulin G1 [IgG1] antibody as isotype control) or CTLA4Ig in different doses (0.004, 0.02, 0.1, and 0.5 mg). Rats were retransfused with ACI blood after 28 and 84 days without any additional CTLA4Ig therapy. Weekly sera samples were tested for alloantibody against donor leukocytes using flow cytometry. CTLA4Ig caused a dose-dependent decrease in the IgM alloantibody response against donor major histocompatibility complex (MHC) class I antigens. In addition, 0.02-, 0.1-, and 0.50-mg doses of CTLA4Ig totally inhibited the IgG responses to the first transfusion, and this immunosuppressive effect persisted for the second and third transfusions. To study the capacity of CTLA4Ig to prevent a secondary immune response, three groups of LEW rats were transfused with ACI blood with no accompanying treatment. Animals were retransfused 28 days later with ACI blood together with L6 control antibody or 0.5 or 2.5 mg CTLA4Ig. CTLA4Ig, but not L6, prevented an increase in IgG alloantibody response despite repeated transfusions. The effects of CTLA4Ig treatment on helper T-lymphocyte proliferation was tested by limiting dilution analysis (LDA). Peripheral blood cells taken 30 days after blood transfusion and CTLA4Ig treatment contained significantly decreased donor-specific T-lymphocyte precursors compared with L6-treated rats. These data support the idea that blocking the B7/CD28 signal of T-lymphocyte activation by CTLA4Ig treatment at the time of transfusion may be an important therapeutic tool to inhibit alloantibody responses to blood transfusions.

Abatacept↗
PubMed1996

Inhibition of complement, evoked antibody, and cellular response prevents rejection of pig-to-primate cardiac xenografts.

Complement (C) inhibition alone using a recombinant soluble form of complement receptor type 1 (sCR1) prevents hyperacute rejection but not subsequent irreversible accelerated acute rejection of discordant pig-to-cynomolgus monkey cardiac xenografts, which occurs within 1 week. To inhibit accelerated acute rejection, which is associated with a rise in serum xenoreactive antibody (Ab) and a cellular infiltrate, triple therapy with standard immunosuppressive agents (cyclosporine, cyclophosphamide, and steroids [CCS]) was combined with continuous C inhibition using sCR1. Each of two monkeys that received sCR1 + CCS showed minimal evidence of rejection when killed on days 21 and 32 in comparison to a monkey that received sCR1 + subtherapeutic CCS (rejected at 11 days) and a control that received CCS alone (rejected at 38 min). Prolonged xenograft survival was associated with low Ab levels and a minimal cellular infiltrate, suggesting that combined inhibition of C, xenoreactive Ab responses, and cellular immunity may be a useful approach in overcoming the immune barriers to discordant xenotransplantation.

Animals↗
PubMed1996

Functional activity of anti-C6 antibodies elicited in C6-deficient rats reconstituted by liver allografts. Ability to inhibit hyperacute rejection of discordant cardiac xenografts.

A critical role of the complement membrane attack complex (C5b-9) in mediating hyperacute rejection has been demonstrated previously in fully C6-deficient PVG (C-)(RT1c) rats that reject guinea pig cardiac xenografts at a delayed tempo (45 +/- 9 hr; n=16) compared with C6-sufficient PVG (C+)(RT1c) hosts (0.5 +/- 2 hr; n=6). We have investigated whether selective depletion of C6 from Lewis rats by antibody therapy prevents hyperacute rejection. A polyclonal rat-antirat C6 antibody was induced in PVG (C-) recipients by orthotopic liver transplants from congenic PVG (C+) donors. These liver grafts produced high levels of C6 that reconstituted the complement function of PVG (C-) hosts by 7 days, but the recipients responded within 28 days with the synthesis of an IgG1 antibody to rat C6. The antiserum inhibited hemolytic complement activity of Lewis (RT1(1)) rats in vivo and in vitro. The effect of C6 depletion on Xg survival was investigated by injecting Lewis rats with 2 ml of rat-antirat C6 antiserum before and 1 ml after reperfusion of the guinea pig cardiac xenograft. Lewis rats rejected guinea pig cardiac xenografts after treatment with this rat-antirat C6 antiserum in 38 +/ -11 hr (n=3). Treatment with normal control sera from PVG (C-) rats did not prolong guinea pig cardiac xenograft survival in the Lewis rats (1 +/- 0.7 hr; n=3)(P<0.0043). Injection of 3 ml of the IgG fraction purified from the rat-antirat C6 antibody (33 mg/ml) prolonged xenograft survival to 13.6 +/- 4 hr (n=4) compared with the survival of 0.61 +/- 0.3 hr (n=4) after injection of control rat IgG (33 mg/ml) (P<0.005). These results demonstrate that specific depletion of C6 by antibody therapy has a significant effect on guinea pig cardiac xenograft survival in the Lewis rat. These findings further suggest that C6 depletion may be beneficial to patients undergoing hyperacute rejection of xenografts or allografts.

Animals↗
PubMed1996

Induction of heat shock protein in cardiac allograft rejection--a cyclosporine-suppressible response.

The cellular response to a wide variety of stresses results in the synthesis of a family of proteins termed heat shock proteins (HSPs). To determine if acute allograft rejection could induce these proteins in a transplanted graft, we examined the HSP response to acute cardiac allograft rejection and analyzed the effect of immunosuppression upon this response. Donor hearts obtained from either Lewis (LEW) or ACI rats were heterotopically transplanted in recipient LEW rats. There were 4 experimental groups: untreated isografted (LEW to LEW) animals (n = 14), untreated allografted (ACI to LEW) animals (n = 14), cyclosporine-treated (10 mg/kg SQ/day) isografted animals (n = 12), and cyclosporine-treated allografted animals (n = 12). Animals were sacrificed on posttransplantation day 2, 4, or 6 (time of rejection for untreated allografts); n = 4-5 for each time point per group. At these times tissue obtained from the transplanted heart was examined histologically and analyzed for HSP72 by quantitative Northern and Western blots. The level of HSP72 in the untreated allografts progressively increased between 2, 4, and 6 days posttransplantation and was significantly greater than that of the untreated isografts at all time points. The HSP72 response in cyclosporine-treated allografts was significantly reduced at 4 and 6 days posttransplantation compared with the untreated allografts. In contrast, there was no difference in the HSP response in treated versus untreated isografts. Additionally, there was no difference in HSP levels in cyclosporine-treated isografts and allografts. These findings demonstrate that HSP expression in the transplanted heart correlates directly with the evolution of acute allograft rejection, and that immunosuppressive therapy inhibits the HSP response. These studies also raise the possibility of a functional role for HSPs in the allogeneic immune response.

Animals↗
PubMed1996

Clinical and cost impact of second-opinion pathology. Review of prostate biopsies prior to radical prostatectomy.

Despite numerous studies evaluating second-opinion surgical programs, we are unaware of work evaluating the cost effectiveness of a second opinion for pathology prior to surgery. One of six pathologists reviewed the pathology of the outside needle biopsies of 535 consecutive men referred to Johns Hopkins Hospital for radical prostatectomy over a 12-month period (from October 1993 until October 1994) before the men underwent surgery. Of the 535 needle biopsies initially diagnosed on the outside as adenocarcinoma of the prostate, seven (1.3%) were reclassified as benign upon pathology review at Johns Hopkins Hospital. The most common lesion misinterpreted as adenocarcinoma was adenosis or less pronounced examples of adenosis consisting of foci of crowded glands (five cases). Foci of atrophy in the remaining two cases were misdiagnosed as adenocarcinoma of the prostate. Upon subsequent clinical work up, six of seven men were considered not to have adenocarcinoma, and their surgery was cancelled. The cost for reviewing all 535 preoperative needle biopsies was $44,883, which included the cost of immunohistochemical studies for high-molecular-weight cytokeratin and repeat biopsies and ultrasounds in men whose diagnoses were reversed. The total cost of the radical prostatectomies had the six men undergone surgery was estimated at $85,686, including hospitalization, anesthesia, radical prostatectomy pathology, and surgery. This cost savings did not include other costs resulting from lost wages, morbidity, or potential litigation. Second-opinion pathological evaluation of prostate biopsy before radical prostatectomy is cost effective and has a major impact on clinical treatment for a subset of patients.

Adenocarcinoma↗
PubMed1996

Immunohistochemical manifestations of unilateral kidney ischemia.

Events in the early post-transplant period have been correlated with increased renal allograft loss. Immunologic reactions and ischemic injury have been implicated in this process. While the immunologic aspects of allograft injury have been studied extensively, ischemic effects remain less well understood. To study the effects of ischemia in rats with different genetic backgrounds without the introduction of an alloimmune response, a clamp was placed on the vascular pedicle of the left kidney for 60 min. The short-term effects (1 wk) of ischemia were studied in groups of PVG (RT1c), LEW (RT1), DA (RT1a) and WR (RT1u) rats, Immunoperoxidase staining demonstrated limited infiltration of monocytes, macrophages, and T-cells accompanied by upregulation of low levels of MHC class II antigens on tubular epithelial cells, peritubular capillaries, and interstitial cells in kidneys of PVG and WF rats. Kidneys of LEW and DA rats had greater influxes of monocytes, macrophages, and T cells in addition to higher amounts of MHC class II antigens upregulation on tubular epithelium and interstitial cells. The long-term effects of ischemia were studied in kidneys of WF rats. These kidneys had a progressive increase in infiltrating T cells, monocytes, macrophages and MHC class II expression on the tubular epithelium and the interstitial cells at 14, 30, and 90 d after the ischemic insult. The differences in MHC class II expression between ischemic kidneys of PVG and LEW rats were not associated with differences in production of mRNA for IL-2, IFN-gamma, and TNF-alpha. In summary, transient renal ischemia in the absence of an allogeneic immune response triggers a progression of inflammatory responses, including leukocyte infiltration, cytokine production and MHC class II antigen upregulation which appears to be strain-dependent.

Animals↗