Tarek El-Sawy

Chemokines: directing leukocyte infiltration into allografts

Chemokines have been shown to play a critical role in the recruitment of leukocytes to transplanted organs. Animal models and clinical studies have demonstrated predictable temporal and spatial correlations between chemokine production and leukocyte infiltration into allografts. Antagonism of chemokines or chemokine receptors has been shown to delay leukocyte infiltration and prolong graft function, demonstrating an important role for chemokines in allograft rejection.

Inhibition of Polymorphonuclear Leukocyte–Mediated Graft Damage Synergizes With Short-Term Costimulatory Blockade to Prevent Cardiac Allograft Rejection

Background—The early inflammatory response during reperfusion of cardiac allografts is initiated by the infiltration of polymorphonuclear leukocytes (PMNs) into the graft. The impact of early PMN infiltration on allograft rejection compared with long-term graft survival remains poorly understood. Methods and Results—We tested the role of CXCR2, the receptor for 2 PMN attractant chemokines, KC/CXCL1 and MIP-2/CXCL2, on intragraft inflammation and vascularized cardiac allograft rejection in a murine model. Compared with allografts retrieved from control recipients, both PMN infiltration and intragraft proinflammatory cytokine expression were significantly attenuated in allografts from CXCR2-antisera–treated wild-type or from CXCR2−/− recipients. Adoptive transfer of alloantigen-primed T cells rapidly infiltrated and rejected allografts in control recipients, but T-cell infiltration was significantly decreased in recipients depleted of PMNs at transplantation. The influence of early PMN-mediated inflammation on the therapeutic efficacy of costimulatory blockade to prevent allograft rejection was tested. Short-term treatment of recipients with anti-CD154 mAb or CTLA-4 Ig induced modest prolongation of cardiac allograft survival. However, CD154 mAb or CTLA-4 Ig treatment, combined with either peritransplantation PMN depletion or antibodies specific for KC/CXCL1 plus MIP-2/CXCL2, prolonged cardiac allograft survival beyond 100 days. Conclusions—Results suggest that strategies attenuating PMN-mediated tissue damage during reperfusion significantly improve the efficacy of short-term costimulatory blockade to prevent T-cell–mediated rejection of cardiac allografts.

Neutrophils Mediate Parenchymal Tissue Necrosis and Accelerate the Rejection of Complete Major Histocompatibility Complex-Disparate Cardiac Allografts in the Absence of Interferon-γ

A major feature of acute rejection of cardiac allografts is an intense mononuclear cell infiltration accompanied by interferon (IFN)-gamma production. In the current study we tested the role of IFN-gamma in acute rejection of allografts by comparing the histopathology of rejection in wild-type versus IFN-gamma-/- recipients of major histocompatibility complex-mismatched cardiac grafts. Wild-type recipients rejected the allografts at days 8 to 9 after transplant but rejection was accelerated 2 to 3 days in IFN-gamma-deficient recipients. During rejection in wild-type recipients, the allografts were heavily infiltrated with CD8+ T cells and other mononuclear cells. In contrast, allografts in IFN-gamma-deficient recipients had few T cells but an intense neutrophil infiltration accompanied by extensive graft parenchymal necrosis. No difference in expression levels of neutrophil chemoattractants including Groalpha/KC, MIP-2, GCP-2, and MIP-1alpha, was observed in allografts retrieved from wild-type and IFN-gamma-/- recipients. Depletion of neutrophils from IFN-gamma-deficient recipients delayed rejection until days 8 to 10 after transplant and restored the histopathology of acute allograft rejection to that observed in allografts rejected by wild-type recipients. These results indicate the potent regulatory properties of IFN-gamma during acute rejection directed at neutrophil infiltration into allografts and mediating graft tissue necrosis.

Alloreactive T Cell Responses and Acute Rejection of Single Class II MHC-Disparate Heart Allografts Are under Strict Regulation by CD4+CD25+ T Cells

Skin but not vascularized cardiac allografts from B6.H-2bm12 mice are acutely rejected by C57BL/6 recipients in response to the single class II MHC disparity. The underlying mechanisms preventing acute rejection of B6.H-2bm12 heart allografts by C57BL/6 recipients were investigated. B6.H-2bm12 heart allografts induced low levels of alloreactive effector T cell priming in C57BL/6 recipients, and this priming was accompanied by low-level cellular infiltration into the allograft that quickly resolved. Recipients with long-term-surviving heart allografts were unable to reject B6.H-2bm12 skin allografts, suggesting potential down-regulatory mechanisms induced by the cardiac allografts. Depletion of CD25+ cells from C57BL/6 recipients resulted in 15-fold increases in alloreactive T cell priming and in acute rejection of B6.H-2bm12 heart grafts. Similarly, reconstitution of B6.Rag−/− recipients with wild-type C57BL/6 splenocytes resulted in acute rejection of B6.H-2bm12 heart grafts only if CD25+ cells were depleted. These results indicate that acute rejection of single class II MHC-disparate B6.H-2bm12 heart allografts by C57BL/6 recipients is inhibited by the emergence of CD25+ regulatory cells that restrict the clonal expansion of alloreactive T cells.

Early T cell response to allografts occuring prior to alloantigen priming up-regulates innate-mediated inflammation and graft necrosis

The early inflammatory response within organ allografts is initiated by ischemia/reperfusion (I/R) and promotes subsequent alloantigen-primed T cell recruitment into and rejection of the graft. Polymorphonuclear leukocyte (PMN)-mediated tissue damage is a primary component of the early inflammation in allograft rejection. We sought to compare and elucidate the mechanism of early PMN infiltration into cardiac isografts and allografts. Despite identical production of PMN attractant chemokines, PMN infiltration following reperfusion into syngeneic and allogeneic grafts was not equivalent. PMN infiltration into isografts peaked at 9 to 12 hours post-transplant and quickly resolved. In contrast, PMN infiltration into allografts continued to elevated levels, peaking at 24 hours post-reperfusion. This amplified PMN infiltration into allografts did not resolve until 72 hours post-reperfusion and was accompanied by marked parenchymal necrosis. This early innate inflammatory response was regulated by IFN-gamma-producing CD8+ T cells present in the recipient before detectable alloantigen T cell priming. Co-culture with CD62L(low) CD8+ T cells, but not CD62L(high) CD8+ or CD62L(low) CD4+ T cells, harvested from naïve animals induced allogeneic endothelial cells to express IFN-gamma-dependent chemokines. These data demonstrate CD8+ T cell-mediated attack on the vascular endothelium of allografts within hours following organ reperfusion that amplifies innate immune-mediated intra-graft inflammation and necrosis.

Percutaneous endocardial transfer and expression of genes to the myocardium utilizing fluoroscopic guidance.

Experimental studies indicate that administration of angiogenic proteins or genes by the epicardial or intracoronary route can stimulate development of new collateral vessels and improve myocardial perfusion. An endocardial catheter‐based approach to this therapy would obviate the need for surgery, while preserving the effectiveness of direct intramyocardial administration. Fluoroscopic guidance and prototype, preformed, coaxial catheters were used to examine the feasibility of percutaneous catheter‐based adenovirus (Ad)‐mediated gene transfer and expression in normal swine myocardium. The feasibility of intramyocardial administration (100 μl/injection) of a radiocontrast agent and black tissue dye to all regions of the left ventricle (septum, anterior, lateral, and inferior wall) was confirmed fluoroscopically and on postmortem examination. Injections of replication‐deficient adenovirus (10 injections of 1011 particle units/100 μl each) coding for β‐galactosidase (Adβgal) or vascular endothelial growth factor (AdGVVEGF121.10) were administered to the left ventricular free wall to examine endocardial based gene transfer and expression. β‐Galactosidase activity was detected by histochemical staining and quantitative assay in targeted regions of the myocardium. Regional VEGF expression was found to be significantly greater in targeted regions (1.3 ± 0.4 ng/mg protein) as compared with non‐targeted regions (0.3 ± 0.1 ng/mg protein) or regions injected with control (Adβgal) virus (0.2 ± 0.03 ng/mg protein, P < 0.001). Catheter‐based Ad mediated endocardial gene transfer and expression is feasible using percutaneous, fluoroscopically guided, preformed, coaxial catheters. This approach should be clinically useful to administer angiogenic genes to the ischemic myocardium. Cathet Cardiovasc Intervent 2001;52:260–266.

Exogenous control of cardiac gene therapy: Evidence of regulated myocardial transgene expression after adenovirus and adeno-associated virus transfer of expression cassettes containing corticosteroid response element promoters

OBJECTIVE Because of the relative inaccessibility of the heart for repeated gene therapy, it would be useful to regulate the expression of transgenes delivered in a single dose of a gene therapy vector. Incorporation into the vector of a regulatable promoter that is responsive to pharmacologic agents that are widely used and well tolerated in clinical practice represents such a control strategy. METHODS A replication-deficient adenovirus or an adeno-associated virus containing a chimeric promoter composed of 5 glucocorticoid response elements and the murine thrombopoietin complementary DNA (AdGRE.mTPO or AAVGRE.mTPO) was administered to the hearts of Sprague-Dawley rats. Platelet levels were evaluated as a reporter of transgene activity with or without dexamethasone. For comparison, rats received a control adenovirus vector, AdCMV.mTPO or AdCMV.Null, and the control adeno-associated virus vector AAVCMV.luc, which encodes for the firefly luciferase (luc) gene. RESULTS Platelet elevation in the AdGRE.mTPO group peaked 4 days after dexamethasone administration, with a return to baseline 1 week after the initial corticosteroid dose. Subsequent dexamethasone administration at 2 and 4 weeks resulted in similar but progressively decreased responses. The AAVGRE.mTPO group had 5 peak platelet levels to a minimum of 2.2-fold with respect to baseline without diminution with subsequent dexamethasone administrations out to 169 days. In contrast, the AdCMV.Null and AAVCMV.luc groups demonstrated no increase in platelet counts and the AdCMV.mTPO group demonstrated a slow rise to a single peak platelet count independent of dexamethasone administration. CONCLUSION It may be possible to control on demand the expression of a gene transferred to the heart. This strategy should be useful in cardiac gene therapy.

Multidisciplinary management of lacrimal sac/nasolacrimal duct carcinomas

Purpose: To determine the rates of globe-sparing treatment and useful final visual function in patients with primary lacrimal sac/nasolacrimal duct carcinomas treated with multidisciplinary therapy. Methods: The medical records of 14 patients with primary lacrimal sac/nasolacrimal duct carcinoma treated at 1 institution were retrospectively reviewed. Results: The patients were 9 men and 5 women; the median age at diagnosis was 58.5 years (range, 45–73 years). Seven patients presented with epiphora, 7 with a palpable mass in the inferomedial orbit, and 2 with dacryocystitis. In 3 patients, the diagnosis of cancer was not considered until during or after dacryocystorhinostomy. Seven patients had squamous cell carcinoma, 2 transitional cell carcinoma, 2 adenoid cystic carcinoma, and 1 each adenocarcinoma, poorly differentiated carcinoma, and inverted papilloma with carcinoma in situ transformation. Nine patients underwent surgical resection of the lacrimal sac and nasolacrimal duct and resection of the medial upper and lower eyelids, including canaliculi, partial ethmoidectomy, and medial maxillectomy. One patient underwent lacrimal sac biopsy only as another primary malignancy was discovered during the work-up for systemic disease. Four patients underwent orbital exenteration because of extensive involvement of the orbital soft tissue. Radiotherapy was recommended for 13 patients; in 1 patient, radiotherapy was not recommended because the patient had an inverted papilloma with carcinoma in situ transformation that was completely excised. The median radiation dose was 60 Gy. Eight patients received chemotherapy either concurrent with radiation therapy (5 patients), as neoadjuvant treatment (1 patient), or for progressive or metastatic disease (3 patients). The median follow-up time was 27 months (range, 6–96 months). In 10 patients, the globe was spared. In 9 of these 10 patients, visual acuity was the same as at baseline or better than 20/40 at last follow up. Conclusions: With multidisciplinary therapy, the eye can be spared and reasonable visual function can be preserved in most patients with primary lacrimal sac/nasolacrimal duct carcinomas.

Prognostic Accuracy of the Seventh Edition vs Sixth Edition of the American Joint Committee on Cancer Tumor Classification for Adenoid Cystic Carcinoma of the Lacrimal Gland

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Clinical value of magnetic resonance imaging and other baseline testing for conjunctival mucosa-associated lymphoid tissue lymphoma

Abstract The objective of this study was to assess the value of magnetic resonance imaging (MRI) of the orbit for conjunctival mucosa-associated lymphoid tissue (MALT) lymphoma. The yield of other staging tests at baseline were also evaluated. Twenty-one consecutive patients treated for conjunctival MALT lymphoma were retrospectively studied. Lymphoma was staged according to both the Ann Arbor system and the seventh edition of the AJCC [American Joint Committee on Cancer] cancer staging manual. Findings on MRI of the orbit, whole-body positron emission tomography/computed tomography (PET/CT), CT of the chest/abdomen/pelvis, bone marrow (BM) biopsy and gastrointestinal (GI) endoscopy were recorded. Seventeen patients had orbital MRI. Fourteen of 17 patients (82%) with obvious conjunctival MALT lymphoma on clinical examination had a negative MRI scan. Only three patients had subtle conjunctival enhancement on orbital MRI. Ann Arbor stage at presentation was as follows: stage IE (15 patients), stage IIE (two patients) and stage IV (four patients). Eighteen of 21 patients had total-body PET/CT; four patients (22%) had hypermetabolic activity evident on PET scan. All 21 patients had bilateral BM biopsies. Fifteen of 21 patients (71%) had GI endoscopy. None of the patients had a positive BM biopsy or findings on GI endoscopy. Our data suggest that orbital MRI has a very low yield for identification of conjunctival MALT lymphoma. Clinical examination is critical in diagnosing and assessing treatment response in conjunctival MALT lymphoma. The yield for GI endoscopy and BM biopsy may also be low in staging of conjunctival MALT lymphoma.