Thomas K. Varghese

Allogeneic Transplantation Induces Expression of Cytomegalovirus Immediate-Early Genes In Vivo: a Model for Reactivation from Latency

ABSTRACT Reactivation of cytomegalovirus (CMV) from latency is a frequent complication of organ transplantation, and the molecular mechanism by which this occurs is unknown. Previous studies have shown that allogeneic stimulation induces reactivation of human CMV (HCMV) in vitro (64). We find that transplantation of vascularized allogeneic kidneys induces murine CMV (MCMV) and HCMV immediate-early (ie) gene expression. This induction is accompanied by increased expression of transcripts encoding inflammatory cytokines, including tumor necrosis factor (TNF), interleukin-2, and gamma interferon, and by activation of NF-κB. TNF alone can substitute for allogeneic transplantation in inducing HCMV and MCMV iegene expression in some tissues. Our studies suggest that reactivation is a multistep process which is initiated by factors that induceie gene expression, including TNF and NF-κB. Allogeneic transplantation combined with immunosuppression may be required to achieve complete reactivation in vivo.

Renal Ischemia/Reperfusion Injury Activates the Enhancer Domain of the Human Cytomegalovirus Major Immediate Early Promoter

Reactivation of latent human cytomegalovirus is of significant concern in immunocompromised transplant patients and is likely to occur through transcriptional activation of immediate early (ie) gene expression through mechanisms that are not well understood. TNF‐mediated activation of NF‐κB has been proposed to be one pathway leading to transcriptional activation of CMV ie gene expression. Using transgenic mice carrying a lacZ reporter gene under the control of the HCMV major ie promoter/enhancer (MIEP‐lacZ mice) and MIEP‐lacZ mice deficient in TNF receptor 1 and TNF receptor 2 (MIEP‐lac Z TNFR DKO mice), we demonstrate that renal ischemia/reperfusion (I/R) injury activates the HCMV enhancer independently of TNF. Induction of MIEP‐lacZ expression was preceded by TNFR‐independent formation of reactive oxygen species (ROS), weak and transient activation of 
 NF‐κB and strong and sustained activation of AP‐1. Our studies show that, in addition to TNF‐mediated signaling, TNF‐independent signaling induced by I/R injury can contribute to the activation of the HCMV enhancer. This likely occurs through ROS‐mediated activation of AP‐1. Targeting MAP kinase signaling pathways as well as NF‐κB may be of therapeutic value in patients with CMV infection.

Immunosuppression is not required for reactivation of latent murine cytomegalovirus.

We have shown, for the first time, that TNF induces expression of MCMV IE RNA in the lungs of latently infected mice in the absence of immunosuppression. These initial data suggest that TNF may play an important role in the reactivation of latent MCMV, in the absence of immunosuppression, and provide a provocative insight into the mechanisms of CMV reactivation. Studies are in progress to determine whether genes associated with later stages of the viral life cycle are induced by TNF and whether infectious virus is produced.

Desmoid tumor of the chest wall with pleural involvement

Although there have been reports of desmoid tumors of the chest wall, pleural extension, as well as overall size greater than 20 cm, is rare. We present the case of a large desmoid tumor involving the left anterior chest wall, upper abdomen, and diaphragm, which impinged on the left lung and displaced the liver. Wide surgical excision, reconstruction, and differential diagnosis from fibrosarcoma are essential elements in the treatment of these rare tumors.

TNF receptor independent activation of the cytomegalovirus major immediate early enhancer in response to transplantation.

Background. Reactivation of latent human cytomegalovirus (HCMV) infection is a significant risk factor for long term allograft dysfunction. The molecular pathways involved in reactivation of latent virus have not been identified. Previous studies suggested that tumor necrosis factor (TNF) -mediated activation of nuclear factor of kappa light polypeptide gene enhancer in B-cells (NF-&kgr;B) leading to transcriptional reactivation of viral immediate early (ie) gene expression might be important in transplant-associated viral reactivation. CMV IE gene expression is controlled by the major immediate early promoter/enhancer (MIEP). Because HCMV does not infect mice, transgenic mice carrying a β-galactosidase reporter gene under the control of the HCMV immediate early enhancer (MIEP-lacZ mice) are a valuable model for studying regulation of CMV IE gene expression in vivo. We have used TNF receptor-deficient MIEP-lacZ (MIEP-lacZ TNFR DKO) mice to study the requirement for TNF in transplant-induced activation of the MIEP. Methods. Allogenic kidney transplants were performed using MIEP-lacZ TNFR DKO or MIEP-lacZ TNFRwild-type donor mice. β-Galactosidase activity was used to measure activation of the IE enhancer in donor kidneys at 2 days of posttransplantation and in contralateral controls. Transcription factor activation was assayed with Trans-Am kits. Results. Allogenic and syngenic transplantation activate the HCMV IE enhancer to the same extent. TNF receptor signaling was not required for activation of the MIEP. TNF receptor signaling was required for activation of NF-&kgr;B, but not for activation of activating protein 1 family members junD and Fra-1 in day 2 allografts. Conclusions. TNF-independent pathways can activate the enhancer in response to allogenic transplantation. This may occur through activation of MIEP-binding transcription factors other than NF-&kgr;B.

Endoscopic Management of Central Airway and Esophageal Obstruction and Fistulae

Curative surgical resection is achieved in only about 20% of patients with thoracic malignancy, and only 14% to 16% of patients overall will survive 5 years. Palliation thus becomes an integral part of the management of these patients. This article reviews and illustrates several endoscopic treatment options for disabling obstruction to swallowing and airflow and for addressing aspiration symptoms arising from malignant aerodigestive fistulae.