Antitumor activity of natural pigment violacein against osteosarcoma and rhabdomyosarcoma cell lines

PURPOSE

Sarcomas are rare and heterogenic tumors with unclear etiology. They develop in bone and connective tissue, mainly in pediatric patients. To increase efficacy of current therapeutic options, natural products showing selective toxicity to tumor cells are extensively investigated. Here, we evaluated antitumor activity of bacterial pigment violacein in osteosarcoma (OS) and rhabdomyosarcoma (RMS) cell lines.

METHODS

The toxicity of violacein was assessed in vitro and in vivo, using MTT assay and FET test. The effect of violacein on cell migration was monitored by wound healing assay, cell death by flow cytometry, uptake of violacein by fluorescence microscopy, generation of reactive oxygen species (ROS) by DCFH-DA assay and lipid peroxidation by TBARS assay.

RESULTS

Violacein IC50 values for OS and RMS cells were in a range from 0.35 to 0.88 µM. Its selectivity toward malignant phenotype was confirmed on non-cancer V79-4 cells, and it was safe in vivo, for zebrafish embryos in doses up to 1 µM. Violacein induced apoptosis and affected the migratory potential of OS and RMS cells. It was found on the surfaces of tested cells. Regarding the mechanism of action, violacein acted on OS and RMS cells independently of oxidative signaling, as judged by no increase in intracellular ROS generation and no lipid peroxidation.

CONCLUSION

Our study provided further evidence that reinforces the potential of violacein as an anticancer agent and candidate to consider for improvement of the effectiveness of traditional OS and RMS therapies.

Acute Coronary Syndrome Presenting during On- and Off-Hours: Is There a Difference in a Tertiary Cardiovascular Center?

Background and Objectives: ACS presents an acute manifestation of coronary artery disease and its treatment is based on timely interventional diagnostics and PCI. It has been known that the treatment and the outcomes are not the same for all the patients with ACS during the working day, depending on the availability of the procedures and staff. The aim of the study was to explore the differences in clinical characteristics and outcomes in patients admitted for ACS during on- and off-hours. Materials and Methods: The retrospective study included 1873 consecutive ACS patients admitted to a tertiary, university hospital that underwent coronary angiography and intervention. On-hours were defined from Monday to Friday from 07:30 h to 14:30 h, while the rest was considered off-hours. Results: There were more males in the off-hours group (on-hours 475 (56%) vs. off-hours 635 (62%); p = 0.011), while previous MI was more frequent in the on-hours group (on 250 (30%) vs. off 148 (14%); p < 0.001). NSTEMI was more frequent during on-hours (on 164 (19%) vs. off 55 (5%); p < 0.001), while STEMI was more frequent during off-hours (on 585 (69%) vs. off 952 (93%); p < 0.001). Patients admitted during on-hours had more multivessel disease (MVD) (on 485 (57%) vs. off 489 (48%); p = 0.006), as well as multivessel PCI (on 187 (22%) vs. off 171 (16%); p = 0.002), while radial access was preferred in off-hours patients (on 692 (82%) vs. off 883 (86%); p = 0.004). Left main PCI was performed with similar frequency in both groups (on 37 (4%) vs. off 35 (3%); p = 0.203). Death occurred with similar frequency in both groups (on 17 (2.0%) vs. off 26 (2.54%); p = 0.404), while major adverse cardio-cerebral events (MACCEs) were more frequent in the on-hours group (on 105 (12.4%) vs. off 70 (6.8%); p = 0.039) probably due to the more frequent repeated PCI (on 49 (5.8%) vs. off 27 (2.6%); p = 0.035). Conclusions: Patients admitted for ACS during working hours in a tertiary hospital present with more complex CAD, have more demanding interventions, and experience more MACCEs during follow-up mostly due to myocardial infarctions and repeated procedures.

The imPAct of Trimetazidine on MicrOcirculation after Stenting for stable coronary artery disease (PATMOS study)

Background

Myocardial ischemia is caused by epicardial coronary artery stenosis or atherosclerotic disease affecting microcirculation. Trimetazidine (TMZ), promotes glucose oxidation which optimizes cellular energy processes in ischemic conditions. Small studies demonstrated protective effects of TMZ in terms of reducing myocardial injury after percutaneous coronary intervention (PCI), its effect on microcirculation using contemporary investigative methods has not been studied. The aim of the study was to examine effects of trimetazidine, given before elective PCI, on microcirculation using invasively measured index of microcirculatory resistance (IMR).

Methods

This was prospective, single blinded, randomized study performed in a single university hospital. It included consecutive patients with an indication for PCI of a single, de novo, native coronary artery lesion. Patients were randomly assigned to receive either TMZ plus standard therapy (TMZ group) or just standard therapy. Coronary physiology indices fractional flow reserve (FFR), coronary flow reserve (CFR) and index of microcirculatory resistance (IMR) were measured before and after PCI using coronary pressure wire.

Results

We randomized 71 patients with similar clinical characteristics and risk profile, previous medications and coronary angiograms. Patientshad similar values of Pd/Pa, FFR and CFR prior to PCI procedure. After PCI, FFR values were higher in TMZ group, while IMR values were lower in this group respectively (FFR TMZ + 0.89 ± 0.05 vs. TMZ - 0.85 ± 0.06, p = 0.007; CFR TMZ + 2.1 ± 0.8 vs. TMZ- 2.3 ± 1.3, p = 0.469; IMR TMZ + 18 ± 9 vs. TMZ- 24 ± 12, p = 0.028). In two-way repeated measures ANOVA PCI was associated with change in FFR values (TMZ p = 0.050; PCI p < 0.001; p for interaction 0.577) and TMZ with change in IMR values (TMZ p = 0.034, PCI p = 0.129, p for interaction 0.344).

Conclusion

Adding trimetazidine on top of medical treatment prior to elective PCI reduces microvascular dysfunction by lowering postprocedural IMR values when compared to standard therapy alone.

The stress responsive gene ankrd1a is dynamically regulated during skeletal muscle development and upregulated following cardiac injury in border zone cardiomyocytes in adult zebrafish

Ankyrin repeat domain 1 (ANKRD1) is a functionally pleiotropic protein found in the nuclei and sarcomeres of cardiac and skeletal muscles, with a proposed role in linking myofibrilar stress and transcriptional regulation. Rapid upregulation of its expression in response to both physiological and pathological stress supports the involvement of ANKRD1 in muscle tissue adaptation and remodeling. However, the exact role of ANKRD1 remains poorly understood. To begin to investigate its function at higher resolution, we have generated and characterized a TgBAC(ankrd1a:EGFP) zebrafish line. This reporter line displays transgene expression in slow skeletal muscle fibers during development and exercise responsiveness in adult cardiac muscle. To better understand the role of Ankrd1a in pathological conditions in adult zebrafish, we assessed ankrd1a expression after cardiac ventricle cryoinjury and observed localized upregulation in cardiomyocytes in the border zone. We show that this expression in injured hearts is recapitulated by the TgBAC(ankrd1a:EGFP) reporter. Our results identify novel expression domains of ankrd1a and suggest an important role for Ankrd1a in the early stress response and regeneration of cardiac tissue. This new reporter line will help decipher the role of Ankrd1a in striated muscle stress response, including after cardiac injury.

Early Selective C-Reactive Protein Apheresis in a Patient with Acute ST Segment Elevation Myocardial Reinfarction

The patient was admitted for urgent coronary angiography following an acute anterior ST segment elevation myocardial reinfarction (STEMI) caused by acute stent thrombosis. A stent had been implanted 10 days prior to the reinfarction for an acute anterior STEMI. However, the patient had stopped taking ticagrelor post-discharge. Primary percutaneous coronary intervention of the left anterior descending artery was performed. Subsequently, due to a high C-reactive protein (CRP) level, 3 CRP apheresis sessions were performed, with the first session starting 12 h after the onset of symptoms. A significant drop in CRP was noted after each apheresis. The post-procedural course was uneventful.

Characterization of zebrafish (Danio rerio) muscle ankyrin repeat proteins reveals their conserved response to endurance exercise

Muscle proteins with ankyrin repeats (MARPs) ANKRD1 and ANKRD2 are titin-associated proteins with a putative role as transcriptional co-regulators in striated muscle, involved in the cellular response to mechanical, oxidative and metabolic stress. Since many aspects of the biology of MARPs, particularly exact mechanisms of their action, in striated muscle are still elusive, research in this field will benefit from novel animal model system. Here we investigated the MARPs found in zebrafish for protein structure, evolutionary conservation, spatiotemporal expression profiles and response to increased muscle activity. Ankrd1 and Ankrd2 show overall moderate conservation at the protein level, more pronounced in the region of ankyrin repeats, motifs indispensable for their function. The two zebrafish genes, ankrd1a and ankrd1b, counterparts of mammalian ANKRD1/Ankrd1, have different expression profiles during first seven days of development. Mild increase of ankrd1a transcript levels was detected at 72 hpf (1.74±0.24 fold increase relative to 24 hpf time point), while ankrd1b expression was markedly upregulated from 24 hpf onward and peaked at 72 hpf (92.18±36.95 fold increase relative to 24 hpf time point). Spatially, they exhibited non-overlapping expression patterns during skeletal muscle development in trunk (ankrd1a) and tail (ankrd1b) somites. Expression of ankrd2 was barely detectable. Zebrafish MARPs, expressed at a relatively low level in adult striated muscle, were found to be responsive to endurance exercise training consisting of two bouts of 3 hours of forced swimming daily, for five consecutive days. Three hours after the last exercise bout, ankrd1a expression increased in cardiac muscle (6.19±5.05 fold change), while ankrd1b and ankrd2 were upregulated in skeletal muscle (1.97±1.05 and 1.84±0.58 fold change, respectively). This study provides the foundation to establish zebrafish as a novel in vivo model for further investigation of MARPs function in striated muscle.

Effect of Elective Bentall Procedure on Left Ventricular Systolic Function and Functional Status: Long-Term Follow-Up in 90 patients

Because there are so few data on the long-term effects on left ventricular systolic function and functional status in patients who electively undergo Bentall procedures, we established a retrospective study group of 90 consecutive patients. This group consisted of 71 male and 19 female patients (mean age, 54 ± 10 yr) who had undergone the Bentall procedure to correct aortic valve disease and aneurysm of the ascending aorta, from 1997 through 2003 in a single tertiary-care center. We monitored these patients for a mean period of 117 ± 41 months for death, left ventricular ejection fraction and volume indices, and functional capacity as determined by New York Heart Association (NYHA) class. There were no operative deaths. The survival rate was 73.3% during follow-up. There were 10 cardiac and 13 noncardiac deaths, and 1 death of unknown cause. Echocardiography was performed before the index procedure and again after 117 ± 41 months. In surviving patients, statistically significant improvement in left ventricular ejection fraction, in comparison with preoperative values (0.49 ± 0.11 vs 0.41 ± 0.11; P <0.0001), was noted at follow-up. Similarly, we observed statistically significant reductions in left ventricular end-systolic (39.24 ± 28.7 vs 48.77 ± 28.62 mL/m(2)) and end-diastolic volumes (54.63 ± 6.97 vs 59.17 ± 8.92 mL/m(2); both P <0.0001). Most patients (53/66 [80.3%]) progressed from a higher to a lower NYHA class during the follow-up period. The Bentall procedure significantly improved long-term left ventricular systolic function and functional status in surviving patients who underwent operation on a nonemergency basis.

Stomatin-like protein 2 overexpression in papillary thyroid carcinoma is significantly associated with high-risk clinicopathological parameters and BRAFV600E mutation

Stomatin-like protein 2 (SLP-2), a member of the stomatin protein family, has emerged as a potential molecular hallmark of tumor progression in several human malignancies. The aim of this study was to analyze SLP-2 expression pattern in benign and malignant thyroid tumors (n = 210) and to examine its relationship with clinicopathological parameters and BRAFV600E mutation in thyroid cancer. SLP-2 immunohistochemical expression was not detected in benign adenomas and was absent/weak in follicular and anaplastic carcinomas. High expression levels of SLP-2, found only in papillary thyroid carcinoma (PTC), particularly in the classical variant, were significantly associated with adverse clinicopathological parameters: lymph node metastasis (p = 0.002), extrathyroid invasion (p < 0.001), pT status (p < 0.001), and advanced tumor stage (p = 0.001). Additional genotyping of PTC cases for the BRAFV600E mutation revealed for the first time a close relation between SLP-2 overexpression and the presence of BRAF mutation (p = 0.02) with high positive rates of lymph node metastasis (70%) and extrathyroid invasion (80%) in these cases. The significant association of SLP-2 overexpression with unfavorable clinicopathological characteristics and BRAFV600E mutation indicates that SLP-2 may have a role in aggressiveness of BRAF-mutated PTC and that SLP-2 evaluation could be clinically useful in identification of high-risk PTC patients.

Repeated Injections of IL-2 Break Renal Allograft Tolerance Induced via Mixed Hematopoietic Chimerism in Monkeys

Tolerance of allografts achieved in mice via stable mixed hematopoietic chimerism relies essentially on continuous elimination of developing alloreactive T cells in the thymus (central deletion). Conversely, while only transient mixed chimerism is observed in nonhuman primates and patients, it is sufficient to ensure tolerance of kidney allografts. In this setting, it is likely that tolerance depends on peripheral regulatory mechanisms rather than thymic deletion. This implies that, in primates, upsetting the balance between inflammatory and regulatory alloimmunity could abolish tolerance and trigger the rejection of previously accepted renal allografts. In this study, six monkeys that were treated with a mixed chimerism protocol and had accepted a kidney allograft for periods of 1-10 years after withdrawal of immunosuppression received subcutaneous injections of IL-2 cytokine (0.6-3 × 10(6) IU/m(2) ). This resulted in rapid rejection of previously tolerated renal transplants and was associated with an expansion and reactivation of alloreactive pro-inflammatory memory T cells in the host's lymphoid organs and in the graft. This phenomenon was prevented by anti-CD8 antibody treatment. Finally, this process was reversible in that cessation of IL-2 administration aborted the rejection process and restored normal kidney graft function.

Pilot Study Evaluating Regulatory T Cell-Promoting Immunosuppression and Nonimmunogenic Donor Antigen Delivery in a Nonhuman Primate Islet Allotransplantation Model

The full potential of islet transplantation will only be realized through the development of tolerogenic regimens that obviate the need for maintenance immunosuppression. Here, we report an immunotherapy regimen that combines 1-ethyl-3-(3'-dimethylaminopropyl)-carbodiimide (ECDI)-treated donor lymphoid cell infusion (ECDI-DLI) with thymoglobulin, anti-interleukin-6 receptor antibody and rapamycin to achieve prolonged allogeneic islet graft survival in a nonhuman primate (NHP) model. Prolonged graft survival is associated with Treg expansion, donor-specific T cell hyporesponsiveness and a transient absence of donor-specific alloantibody production during the period of graft survival. This regimen shows promise for clinical translation.

Tolerance of Lung Allografts Achieved in Nonhuman Primates via Mixed Hematopoietic Chimerism

While the induction of transient mixed chimerism has tolerized MHC-mismatched renal grafts in nonhuman primates and patients, this approach has not been successful for more immunogenic organs. Here, we describe a modified delayed-tolerance-induction protocol resulting in three out of four monkeys achieving long-term lung allograft survival without ongoing immunosuppression. Two of the tolerant monkeys displayed stable mixed lymphoid chimerism, and the other showed transient chimerism. Serial biopsies and post-mortem specimens from the tolerant monkeys revealed no signs of chronic rejection. The tolerant recipients also exhibited T cell unresponsiveness and a lack of alloantibody. This is the first report of durable mixed chimerism and successful tolerance induction of MHC-mismatched lungs in primates.

Neutrophil elastase gene polymorphisms: modulators of response to therapy in childhood bronchiectasis?

BACKGROUND

The aim of this study was to investigate polymorphisms in the promoter region of the neutrophil elastase (ELANE) gene as potential modulators of the therapeutic response in children with idiopathic bronchiectasis.

METHODS

The study included 48 children between 5 and 17 years old who were diagnosed with idiopathic bronchiectasis based on high-resolution computed tomography of the thorax. In all patients therapy included administration of antibiotics, anti-inflammatory drugs, expectorants, and postural drainage. Response to therapy was evaluated by the change in FeNO levels before and after administration of therapy. The ELANE promoter region polymorphisms were analyzed by PCR-direct DNA sequencing.

RESULTS

According to the predicted activity of ELANE genotypes, subjects were divided into two groups: low/intermediate activity (n = 18) and high activity (n = 30). Subjects in the group with high-activity genotype had higher initial FeNO levels and this difference was statistically significant (t = 2.906; p = 0.006). The difference between FeNO levels before and after therapy was also statistically significantly higher in children with high-activity genotype (t = 3.329; p = 0.002). Statistically significant correlation was observed between the change in FeNO levels and ELANE genotypes (r = 0.350; p = 0.015).

CONCLUSION

Children with high-activity genotype had higher initial FeNO levels and showed better response to therapy than children with low/intermediate-activity genotypes.

Low-dose IL-2 for In vivo expansion of CD4+ and CD8+ regulatory T cells in nonhuman primates

IL-2 is a known potent T cell growth factor that amplifies lymphocyte responses in vivo. This capacity has led to the use of high-dose IL-2 to enhance T cell immunity in patients with AIDS or cancer. However, more recent studies have indicated that IL-2 is also critical for the development and peripheral expansion of regulatory T cells (Tregs). In the current study, low-dose IL-2 (1 million IU/m(2) BSA/day) was administered to expand Tregs in vivo in naïve nonhuman primates. Our study demonstrated that low-dose IL-2 therapy significantly expanded peripheral blood CD4(+) and CD8(+) Tregs in vivo with limited expansion of non-Treg cells. These expanded Tregs are mainly CD45RA(-) Foxp3(high) activated Tregs and demonstrated potent immunosuppressive function in vitro. The results of this preclinical study can serve as a basis to develop Treg immunotherapy, which has significant therapeutic potential in organ/cellular transplantation.

Feasibility of semi-quantitative assessment of left ventricular contractile reserve in dilated cardiomyopathy

BACKGROUND

We and others have shown previously that left ventricular (LV) contractile reserve assessed quantitatively by high-dose dobutamine stress-echocardiography (DSE) has prognostic implications in patients with dilated cardiomyopathy.

PURPOSE

To assess the feasibility of semi-quantitative assessment of LV contractile reserve by differently skilled operators in patients with dilated cardiomyopathy.

METHODS

High-dose DSE was performed in 63 consecutive patients, mean age 50 ± 10 years and ejection fraction (EF) 19 ± 8%. LVEF was calculated 1) using Simpson's biplane formula, and 2) semi-quantitatively (5% increments) by novice and experienced echocardiographers, and by a DSE expert. Patients were considered to have preserved LV contractile reserve if LVEF dobutamine-induced change was ≥5%.

RESULTS

Twenty-seven (45.8%) patients died during the 5-year follow-up. The feasibility of the assessment was 89%, 94%, and 98% for novice and experienced readers and DSE expert, respectively. Kaplan-Meier analysis showed that LV contractile reserve assessed semi-quantitatively by DSE expert and experienced reader achieved the best prognostic separation (log rank 19.63 and 18.99, respectively, p < 0.001 for both), followed by quantitative assessment (log rank 9.76, p = 0.0018) and assessment by novice reader (log rank 8.76, p = 0.012). Areas under the curves were similar for quantitative and semi-quantitative assessment of LV contractile reserve.

CONCLUSIONS

Our data indicate that semi-quantitative assessment of LV contractile reserve is feasible by differently skilled operators.

Overcoming memory T-cell responses for induction of delayed tolerance in nonhuman primates

The presence of alloreactive memory T cells is a major barrier for induction of tolerance in primates. In theory, delaying conditioning for tolerance induction until after organ transplantation could further decrease the efficacy of the regimen, since preexisting alloreactive memory T cells might be stimulated by the transplanted organ. Here, we show that such "delayed tolerance" can be induced in nonhuman primates through the mixed chimerism approach, if specific modifications to overcome/avoid donor-specific memory T-cell responses are provided. These modifications include adequate depletion of CD8+ memory T cells and timing of donor bone marrow administration to minimize levels of proinflammatory cytokines. Using this modified approach, mixed chimerism was induced successfully in 11 of 13 recipients of previously placed renal allografts and long-term survival without immunosuppression could be achieved in at least 6 of these 11 animals.

Repair of hammock mitral valve with hypoplastic posterior leaflet in an adult

BACKGROUND AND AIM OF THE STUDY

Congenital hammock mitral valves are rarely discovered in adulthood. The case is presented of a 29-year-old woman in NYHA functional class III and with markedly depressed left ventricular (LV) function, who underwent surgery for severe mitral regurgitation.

METHODS AND RESULTS

Preoperative transthoracic echocardiography showed grade 3+/4 mitral regurgitation due to restricted leaflet motion, and an almost immobile posterior leaflet due to the attachment of fibrotic chordae high on the posterior LV wall. At surgery, limited motion of both leaflets and partial agenesis of the posterior leaflet were found. The valve was repaired by resecting the posterior leaflet defect, mobilizing the papillary muscle, and then widening the posterior leaflet. Postoperative echocardiography revealed no further mitral regurgitation, and the valve remained competent despite a postoperative episode of cardiac decompensation.

CONCLUSION

Hammock mitral valve repair is a highly challenging procedure, particularly in patients presenting with LV dilatation. The greatest degree of leaflet mobility must be restored in order to prevent tethering. Thus, it is strongly recommended that the posterior leaflet is systematically widened, even in the presence of an apparently large leaflet surface.

Comparison of valve annuloplasty and replacement for ischemic mitral valve incompetence

OBJECTIVE

Mitral incompetence is a chronic sequela of myocardial infarction. It is caused by apical displacement and tethering of the mitral valve leaflets after myocardial infarction, resulting in incomplete coaptation. The consensus is for mitral valve surgery in the presence of significant ischemic mitral regurgitation (IMR). Previously, the only option was mitral valve replacement (MVR) with a mechanical or tissue valve. The suboptimal results obtained prompted the development of several methods of mitral valve repair. Today, the most commonly used repair is undersized annuloplasty.

METHODS

We conducted a retrospective nonrandomized study of all patients who underwent operation for coronary artery disease and IMR between 2000 and 2006. The surgeon chose the surgical method used for the mitral valve procedure. The most commonly used procedures were restrictive mitral valve annuloplasty (MVP) and MVR with a mechanical prosthesis. We collected all pertinent preoperative, intraoperative, and early-postoperative data. We followed up with phone interviews of the patients and their relatives and with complete clinical and echocardiography examinations.

RESULTS

We carried out operations on 138 patients during the study period (MVR, 52 patients; MVP, 86 patients). The 2 groups had comparable demographic data and risk factors. The 2 groups were significantly different with respect to mean (+/-SD) New York Heart Association (NYHA) class (MVP, 2.72 +/- 0.62; MVR, 2.48 +/- 0.70; P < .01) and ejection fraction (MVP, 29.01% +/- 11.00%; MVR, 35.87% +/- 11.00%; P </= .01). The 30-day mortality rates for the MVR and MVP groups were significantly different (9.61% and 5.81%, respectively; P < .01). Our follow-up included 83% of the patients and continued for up to 84 months. The 2 groups showed no significant difference in mortality by the end of follow-up; however, the MVR patients had a better ejection fraction (37.79% versus 29.86%) and NYHA functional class (1.88 +/- 0.498 versus 2.36 +/- 0.564; P < .01).

CONCLUSION

Correcting chronic IMR with either repair or replacement produces a good mid-term survival rate (approximately 75%) for survivors in NYHA classes I and II. In our study, mortality rates for the MVP and MVR groups were similar, even though the repair group had a lower mean ejection fraction and a higher NYHA class before and after the operation. We therefore conclude that repair is superior to replacement in treating ischemic mitral insufficiency. A prospective randomized study is needed to better compare these 2 approaches.

Four stages and lack of stable accommodation in chronic alloantibody-mediated renal allograft rejection in Cynomolgus monkeys

The etiology of immunologically mediated chronic renal allograft failure is unclear. One cause is thought to be alloantibodies. Previously in Cynomolgus monkeys, we observed a relationship among donor-specific alloantibodies (DSA), C4d staining, allograft glomerulopathy, allograft arteriopathy and progressive renal failure. To define the natural history of chronic antibody-mediated rejection and its effect on renal allograft survival, we now extend this report to include 417 specimens from 143 Cynomolgus monkeys with renal allografts. A subset of animals with long-term renal allografts made DSA (48%), were C4d positive (29%), developed transplant glomerulopathy (TG) (22%) and chronic allograft arteriopathy (CAA) (19%). These four features were highly correlated and associated with statistically significant shortened allograft survival. Acute cellular rejection, either Banff type 1 or 2, did not correlate with alloantibodies, C4d deposition or TG. However, endarteritis (Banff type 2) correlated with later CAA. Sequential analysis identified four progressive stages of chronic antibody-mediated rejection: (1) DSA, (2) deposition of C4d, (3) TG and (4) rising creatinine/renal failure. These new findings provide strong evidence that chronic antibody-mediated rejection develops without enduring stable accommodation, progresses through four defined clinical pathological stages and shortens renal allograft survival.

Depletion of CD8 memory T cells for induction of tolerance of a previously transplanted kidney allograft

Heterologous immunologic memory has been considered a potent barrier to tolerance induction in primates. Induction of such tolerance for a previously transplanted organ may be more difficult, because specific memory cells can be induced and activated by a transplanted organ. In the current study, we attempted to induce tolerance to a previously transplanted kidney allograft in nonhuman primates. The conditioning regimen consisted of low dose total body irradiation, thymic irradiation, antithymocyte globulin, and anti-CD154 antibody followed by a brief course of a calcineurin inhibitor. This regimen had been shown to induce mixed chimerism and allograft tolerance when kidney transplantation (KTx) and donor bone marrow transplantation (DBMT) were simultaneously performed. However, the same regimen failed to induce mixed chimerism when delayed DBMT was performed after KTx. We found that significant levels of memory T cells remained after conditioning, despite effective depletion of naïve T cells. By adding humanized anti-CD8 monoclonal antibody (cM-T807), CD8 memory T cells were effectively depleted and these recipients successfully achieved mixed chimerism and tolerance. The current studies provide 'proof of principle' that the mixed chimerism approach can induce renal allograft tolerance, even late after organ transplantation if memory T-cell function is adequately controlled.

Chronic antibody mediated rejection of renal allografts: pathological, serological and immunologic features in nonhuman primates

The pathogenesis of late renal allograft loss is heterogeneous and difficult to diagnose. We have analyzed renal allografts in nonhuman primates to determine the relationship between alloantibodies and the graft pathology of late graft loss. Seventeen Cynomolgus monkeys were chosen from among those on several protocols for renal allotransplantation with mixed chimerism induction so that animals with and without alloantibodies were included. All animals received transient CD154 blockade and short-term cyclosporine treatment until day 28. Serial blood samples were tested for alloantibodies. Protocol biopsies and autopsy kidneys were scored for pathology and C4d deposition. Group 1, defined by complete lack of C4d deposition (24 tissue samples; 8 recipients), had no detectable alloantibodies (33 serum samples; 1-7 samples per recipient) and no evidence of chronic rejection. Three survived greater than 2 years with normal function and histology. Group 2, defined as having C4d deposition in peritubular capillaries, all made alloantibodies (100%), and most grafts later showed chronic allograft glomerulopathy (89%), and/or arteriopathy (89%). All grafts in Group 2 failed (3-27 months). Pathologic lesions of typical of chronic rejection in humans develop in monkeys, correlate with antecedent alloantibodies/C4d deposition and predict chronic rejection rather than durable accommodation.

Long-term islet allograft function in the absence of chronic immunosuppression: a case report of a nonhuman primate previously made tolerant to a renal allograft from the same donor

Development of mixed chimerism by donor bone marrow transplantation (DBMT) has led to long-term tolerance of solid organ allografts in nonhuman primates. As an initial attempt to extend this approach to cellular transplant, islet transplant from the same donor was attempted in the recipient previously made tolerant to a kidney allograft.

METHODS

After the conditioning with ATG, total body irradiation, thymic irradiation, and splenectomy, DBMT was performed followed by 4 weeks of cyclosporine. Kidney transplantation and native nephrectomies were subsequently performed on day 89. After 2.8 years of DBMT, diabetes was induced by streptozocin (STZ) and islets from bone marrow and kidney donor were transplanted without immunosuppression.

RESULTS

After DBMT, the recipient developed chimerism and no evidence of kidney rejection for more than 1000 days. STZ induced diabetes was reversed after the islet transplantation. Islet biopsies demonstrated insulin staining without rejection. Although the recipient became diabetic 300 days after islet transplantation, viable transplanted islets were found in the liver and under the kidney capsule without any evidence of rejection.

CONCLUSION

Tolerance with a nonmyeloablative conditioning can allow successful pancreatic islet transplantation without immunosuppression. Because no histological evidence of rejection was identified, recurrent diabetes is presumed to be inadequate islet mass.

Association of natural killer cell depletion with induction of mixed chimerism and allograft tolerance in non-human primates

BACKGROUND

Nonmyeloablative T cell depletion followed by donor bone marrow infusion has proved to be an effective approach to induction of mixed chimerism and tolerance of organ allografts in non-human primates. To help define the mechanisms involved we have compared T cell depletion with ATG versus anti-CD2 monoclonal antibody with respect to establishment of mixed chimerism and induction of tolerance.

METHOD

Both nonmyeloablative regimens included low dose total body irradiation (1.5 Gy x 2), thymic irradiation (7 Gy), splenectomy and kidney plus donor bone marrow transplantation, followed by a 4-week posttransplant course of cyclosporine. In addition, the ATG group (13 recipients) received antithymocyte globulin, although the LOCD2b group (10 recipients) were treated with an anti-CD2 monoclonal antibody (LOCD2b).

RESULTS

In the ATG group, 11 of 13 monkeys developed multilineage chimerism and 9 survived for more than 100 days without kidney allograft rejection. In contrast, 0/10 monkeys in the LOCD2b group developed chimerism, 5 died of infection and 5 suffered progressive rejection; only 1 recipient survived beyond 100 days. Sequential monitoring of peripheral blood mononuclear cells revealed greater T cell (CD3+) depletion in the LOCD2b-treated animals compared to those receiving ATG. However, NK cells (CD16+CD8+) were significantly more depleted in the ATG group and NK function remained abrogated longer after ATG than LOCD2b treatment (3 weeks vs. <5 days).

CONCLUSION

Despite excellent T cell depletion by LoCD2b, ATG was more effective in inducing chimerism and tolerance. This difference correlated with anti-NK activity of the two reagents. These data suggest that NK cells may also resist engraftment of allogeneic bone marrow cells in this model.

Tolerance in a concordant nonhuman primate model

BACKGROUND

We have previously demonstrated that induction of mixed lymphohematopoietic chimerism resulted in donor specific renal allograft tolerance without the need for chronic immunosuppression in nonhuman primates. Here we have tested whether tolerance can be similarly induced for baboon to cynomolgus renal xenografts.

METHODS

After preconditioning with anti-thymocyte globulin (ATG), nonlethal total body irradiation, and thymic irradiation, cynomolgus monkeys underwent splenectomy, native nephrectomies, and baboon marrow and renal transplants. Postoperative cyclosporine was given for 28 days.

RESULTS

In Group 1 (n=2, survival= 13, 14 days), both animals developed anti-donor immunoglobulin G, had biopsy findings consistent with humoral rejection, and showed rapidly progressive xenograft failure. In Group 2 (n=5, survival=1, 16, 33, 112, 190 days), 15-deoxyspergualine was added to the regimen (Day 0-13). In one long-term survivor, donor specific hyporesponsiveness was first observed (mixed lymphocyte culture [(MLR]) on Day 48. MLR reactivity returned on Day 64 together with the development of anti-donor antibody and subsequent xenograft failure on Day 112. Donor specific T-cell hyporesponsiveness was detected in the other long-term survivor for the first 133 days, after which a donor-specific skin xenograft was placed, (survival 24 days). Following the skin graft rejection, a rise in the MLR, development of anti-donor antibody and progressive rejection of the renal xenograft were observed.

CONCLUSIONS

Antibody-mediated rejection seems to constitute the major difference between concordant xenografts and allografts. Addition of 15-deoxyspergualine for 2 weeks posttransplant extended concordant primate xenograft survival to 6 months without chronic immunosuppression. In contrast to the allogeneic model, renal transplant acceptance in this xenogeneic system was interrupted by placement of a donor-specific skin graft.

Long-term outcome and alloantibody production in a non-myeloablative regimen for induction of renal allograft tolerance

BACKGROUND

Multilineage chimerism and long-term acceptance of renal allografts has been produced in non-human primates conditioned with a nonmyeloablative regimen. Our study was undertaken to evaluate the immunological and pathological status of long-term survivors and to define the role of splenectomy and of the primarily vascularized kidney in the regimen.

METHOD

Monkeys were treated with the basic regimen, including: total body irradiation, thymic irradiation, antithymocyte globulin, donor bone marrow transplantation, and a 4-week course of cyclosporine after which no further immunosuppression was given. They were divided into four groups according to the timing of kidney transplantation (KTx) and splenectomy as follows; group A (n=13): KTx and splenectomy on the day of donor bone marrow transplantation (day 0); group B (n=3): KTx on day 0 without splenectomy; group C (n=7): splenectomy on day 0 but delayed KTx until 3 to 16 weeks post-donor bone marrow transplantation; group D (n=3): both splenectomy and KTx delayed until day 120 post-donor bone marrow transplantation.

RESULTS

In group A, 11 of 13 monkeys developed chimerism and 9 monkeys achieved long-term survival of 4 to 70 months without evidence of chronic vascular rejection. Alloantibodies were detected in only one long-term survivor. In contrast, all three monkeys in group B developed alloantibodies and rejected their allografts. In group C, long-term survival without alloantibody production was observed in two of three monkeys that had developed chimerism. In group D, all three recipients were sensitized and rejected the kidney allografts rapidly after transplantation.

CONCLUSIONS

1) Production of anti-donor antibody was prevented in most recipients that developed mixed chimerism in the regimens with splenectomy at the time of donor bone marrow transplantation. 2) If splenectomy is not included in the initial conditioning regimen, induction of B cell tolerance is less likely and the result is late onset of alloantibody production and allograft rejection. 3) Immediate transplantation of the kidney at the time of recipient conditioning is not essential for induction of donor specific hyporesponsiveness by bone marrow transplantation.

Demonstration of multilineage chimerism in a nonhuman primate concordant xenograft model

Prior studies from our laboratory have demonstrated that a nonmyeloablative conditioning regimen can induce transient mixed chimerism and renal allograft tolerance between MHC disparate cynomolgus monkeys. We have also shown that this preparative regimen can be extended to a concordant baboon to cynomolgus xenograft model by adding, to the post transplant protocol, therapy designed to prevent antibody production. Here we examine the use of brequinar (BQR) for this purpose and the efficacy of two new reagents developed to demonstrate the establishment of chimerism in the xenograft recipients. The cynomolgus recipients were conditioned with WBI (300 cGy), TI (700 cGy), ATG, cyclosporine, and brequinar sodium. To detect engraftment of the donor marrow, we prepared a polyclonal cynomolgus anti-baboon antibody (CABA) and a monoclonal antibody (215.1), which distinguish baboon and cynomolgus lymphocytes and granulocytes. We employed flow cytometry analysis to detect multilineage chimerism in the xenograft recipients. Five of the six recipients monitored using our new reagents (CABA and 215.1) developed detectable chimerism and only one of these animals lost its kidney to rejection. However, other complications have not permitted assessment of long-term outcome. The features of the multilineage chimerism included the detection of donor granulocytes (1.8-77.4%) and lymphocytes (2.4-22.2%) for 9 to 37 days. Our new reagents permit the detection of multilineage mixed chimerism, which may be a predictor of xenograft tolerance. We also conclude that brequinar may be effective in preventing antibody formation, but because of its toxicity, it is probably not the drug of choice for extension of the mixed chimerism protocol to concordant xenografts.

Biological effects and fate of a soluble, dimeric, 80-kDa tumor necrosis factor receptor in renal transplant recipients who receive OKT3 therapy

A preliminary clinical study of renal allograft recipients revealed that a dimeric form of the human 80 kDa soluble receptor (sTNFR:Fc) for tumor necrosis factor (TNF) is well tolerated and attenuates the OKT3-induced acute clinical syndrome. The current study determined the in vivo biological effects and fate of sTNFR:Fc in these patients. Serial assessment of both antigenic and biological activities of circulating TNF and sTNFR:Fc have led to the following observations. (1) Although control patients typically responded to the first OKT3 injection with a rapid increase of biologically active TNFalpha, patients on sTNFR:Fc therapy had markedly higher serum TNFalpha antigenic levels, but no detectable bioactivity. Thus, sTNFR:Fc functioned as a potent antagonist, despite its cytokine-carrier effect. (2) Peak sTNFR:Fc levels averaging 800 and 2500 ng/ml were routinely achieved in vivo, using the low-dose (0.05 mg/kg) and high-dose (0.15 mg/kg) protocols. (3) The half-life of circulating sTNFR:Fc was estimated to be approximately 4.4 days, and levels of p80 receptors in treated patients remained significantly above those in control patients for at least 20 days. (4) In vitro blocking studies demonstrated that circulating sTNFR:Fc remained biologically active for 2 weeks. These results demonstrate that under current protocols, significant serum levels of sTNFR:Fc, capable of effectively neutralizing TNF activity over prolonged periods, can be achieved. The persistent OKT3 side effects observed, despite sTNFR:Fc therapy, are therefore likely to be caused by factors other than TNF.

A study of tolerance in a concordant xenograft model

Antibody-mediated rejection appears to constitute the major difference between concordant xenografts and allografts in nonhuman primates. Consistent with its known effect on antibody responses, 5-7 addition of DSG to the conditioning regimen has extended concordant primate xenograft survival for up to 6 months after discontinuation of conventional immunosuppression. In contrast to our observations in recipients of renal allografts, donor-specific skin graft rejection can occur and even in long-term recipients may induce rejection of a previously accepted renal xenograft.

Evaluation of recombinant human soluble dimeric tumor necrosis factor receptor for prevention of OKT3-associated acute clinical syndrome

Tumor necrosis factor alpha (TNFa) has been shown to be the primary cytokine responsible for the OKT3-induced acute clinical syndrome (OKT3-ACS). Recombinant human soluble tumor necrosis factor receptor (TNFR:Fc) is a dimer of the p80 TNF receptor, which binds both TNFa and lymphotoxin (LT). Renal allograft recipients undergoing OKT3 therapy for steroid-resistant rejection were randomized to receive OKT3 alone or in combination with TNFR:Fc to determine its safety and efficacy in decreasing the severity of OKT3-ACS and in restoring renal function. Six of 12 patients were given TNFR:Fc prior to each of the first two injections of OKT3. All patients were monitored for manifestations of OKT3-ACS and changes in renal function. In addition, serial serum samples were assayed for TNFa and TNFR:Fc levels (ELISA) and TNFa bioactivity (L929). No adverse side effects were identified in patients receiving TNFR:Fc. Patients treated with TNFR:Fc had significantly fewer symptoms by day 2 of OKT3, and had a lower overall incidence of chills and arthralgias. Renal dysfunction reversed within 24 hr in the TNFR:Fc-treated group in contrast to the 48-72-hr delay in the control group. Antigenic TNFa levels increased in the control group from < 10 pg/ml pre OKT3 to a mean peak level of 30 +/- 13 pg/ml on day 1 and decreased to pretreatment levels by day 2. TNFR:Fc-treated patients had a mean peak TNFa level of 235 +/- 135 pg/ml, suggesting a carrier effect of TNFR:Fc. In contrast, bioactivity was barely detectable (mean 20 +/- 14 pg/ml) in the day 1 samples from TNFR:Fc-treated patients, whereas significant bioactivity (peak mean 60 +/- 35 pg/ml) was detected in sera from control patients. TNF receptor levels reached 600 ng/ml in treated patients and remained elevated for up to 18 days confirming the long half-life of TNFR:Fc. This phase 1 trial demonstrates that TNFR:Fc is well tolerated and may limit the severity of OKT3-ACS. The most significant observation was a more rapid improvement in renal function in the TNFR:Fc-treated patients. The absence of TNFa bioactivity indicates that TNFR:Fc functions as a TNF antagonist. Further evaluation of higher doses of TNFR:Fc in OKT3-treated patients is currently in progress.