Rebecca M. Minter

Targeted adenovirus-induced expression of IL-10 decreases thymic apoptosis and improves survival in murine sepsis

Sepsis remains a significant clinical conundrum, and recent clinical trials with anticytokine therapies have produced disappointing results. Animal studies have suggested that increased lymphocyte apoptosis may contribute to sepsis-induced mortality. We report here that inhibition of thymocyte apoptosis by targeted adenovirus-induced thymic expression of human IL-10 reduced blood bacteremia and prevented mortality in sepsis. In contrast, systemic administration of an adenovirus expressing IL-10 was without any protective effect. Improvements in survival were associated with increases in Bcl-2 expression and reductions in caspase-3 activity and thymocyte apoptosis. These studies demonstrate that thymic apoptosis plays a critical role in the pathogenesis of sepsis and identifies a gene therapy approach for its therapeutic intervention.

Adenoviral Delivery of Human and Viral IL-10 in Murine Sepsis

Adenovirus (Ad) gene therapy has been proposed as a drug-delivery system for the targeted administration of protein-based therapies, including growth factors and biological response modifiers. However, inflammation associated with Ad transduction has raised concern about its safety and efficacy in acute inflammatory diseases. In the present report, intratracheal and i.v. administration of a first-generation adenoviral recombinant (E1,E3 deleted) either containing an empty cassette or expressing the anti-inflammatory cytokines viral or human IL-10 (IL-10) was administered to mice subjected to zymosan-induced multisystem organ failure or to acute necrotizing pancreatitis. Pretreatment of mice with the intratracheal instillation of Ad expressing human IL-10 or viral IL-10 reduced weight loss, attenuated the proinflammatory cytokine response, and reduced mortality in the zymosan-induced model, whereas pretreatment with a control adenoviral recombinant did not significantly exacerbate the response. Pretreatment of mice with pancreatitis using adenoviral vectors expressing IL-10 significantly reduced the degree of pancreatic and liver injury and liver inflammation when administered systemically, but not intratracheally. We conclude that adenoviral vectors can be administered prophylactically in acute inflammatory syndromes, and expression of the anti-inflammatory protein IL-10 can be used to suppress the underlying inflammatory process.

Prospective evaluation of the giant prosthetic reinforcement of the visceral sac for recurrent and complex bilateral inguinal hernias

BACKGROUNDnRecurrent and complex bilateral inguinal hernias are associated with a high recurrence rate. This study evaluates prospectively the efficacy and safety of giant prosthetic reinforcement of the visceral sac (GPRVS) in a group of patients at high risk for recurrence.nnnMETHODSnSixty-four patients with 124 inguinal hernias (60 bilateral and 4 unilateral) underwent repair using a large polyester mesh based on Stoppas preperitoneal technique. Mean age was 61 years (63 men and 1 woman), and 69% had one or more comorbid medical conditions.nnnRESULTSnFactors predicating a high risk for recurrence included large hernia size (> or =5 cm; 31%, 20 of 64), failure of one or more previous repairs (39%, 25 of 64), and chronic obstructive pulmonary disease (28%, 18 of 64). Mean operative time was 115 minutes (range 45 to 235). Mean length of stay was 3+/-3 days. There were 2 major and 15 minor complications, no mesh infections, and no death. Follow-up was obtained in 95% (61 of 64). After a mean follow-up of 24 months, the recurrence rate was 1% (1 of 124) per inguinal hernia repaired or 2% (1 of 64) per patient.nnnCONCLUSIONnGPRVS is a safe and effective addition to the surgeons armamentarium to treat selected patients with recurrent or complex bilateral inguinal hernias.

Considering immunomodulatory therapies in the septic patient: should apoptosis be a potential therapeutic target?

Treatment of sepsis and septic shock remains a clinical conundrum. Recent prospective trials with anti-cytokine and anti-inflammatory therapies have shown only modest clinical benefit. The successful treatment of the patient with sepsis syndrome will likely require multi-modal therapies aimed at several of the immunological and physiological disturbances which are occurring simultaneously. Recent studies in experimental animals and critically ill patients have suggested that increased apoptosis of lymphoid organs and some parenchymal tissues may contribute to the immune suppression, anergy and organ system dysfunction. Therapies aimed at inhibiting lymphoid cell apoptosis may contribute to improved outcome, and should be considered in the treatment of hospitalized patients with sepsis syndromes. Although clinical trials with anti-apoptotic agents remain distant due in large part to technical difficulties associated with their administration and tissue targeting, inhibition of lymphocyte apoptosis may be an appropriate therapeutic target for the septic patient.

Application of gene therapy to acute inflammatory diseases.

The application of gene therapy to acute inflammation has not received as much research attention as has the treatment of genetically-based diseases, cancer, and viral infections. However, gene therapy as a drug delivery system offers several theoretical and practical advantages over current protein delivery systems. These include the ability to target therapies to individual tissues or cell types, to locally produce proteins that can act intracellularly or in an autocrine, juxtacrine, or paracrine fashion, and to sustain new protein synthesis for periods up to several weeks after a single administration. Although retrovirus, herpes simplex, and adeno-associated virus have been proposed for gene therapy in cancer and in genetic diseases, nonviral and adenovirus approaches appear most applicable as drug delivery systems due to their rapid onset and short duration of transgene expression. The relative modest transduction efficiencies obtained at present with nonviral approaches, and the inherent inflammatory properties of first-generation adenovirus constructs, however, have limited their usefulness to date. The present review discusses the theoretical and practical benefits of specific gene therapy approaches for the treatment of acute inflammatory diseases, as well as our experiences with liposome:plasmid DNA and adenovirus-based approaches. Although a number of technical and theoretical hurdles remain before it can be evaluated in humans with acute inflammation, gene therapy offers a novel approach for the treatment of acute inflammation, and will likely enter the armamentarium of critical care physicians in the near future.

Influence of recombinant adenovirus on liver injury in endotoxicosis and its modulation by IL-10 expression

Adenovirus-based gene therapy offers a unique opportunity to target gene expression to the liver by systemic delivery. However, systemic administration of a first generation adenoviral construct elicits an inflammatory response leading to TNF-alpha-dependent liver injury. The aim of this study was to evaluate whether the systemic administration of recombinant adenovirus exacerbates a subsequent TNF-alpha-dependent liver injury induced by D-galactosamine and lipopolysaccharide. Surprisingly, low-dose adenovirus administration (10(5) particles) protects, while high-dose adenovirus (10(10) particles) is associated with an exaggerated hepatic inflammatory response from a subsequent D-galactosamine and lipopolysaccharide challenge. This exacerbation is TNF-alpha dependent, since treatment with a TNF inhibitor fully protects against the liver injury. Moreover, intravenous administration of an adenoviral construct expressing the anti-inflammatory protein interleukin-10 reduces TNF-alpha appearance and attenuates the increased hepatocyte injury. Taken together, this report demonstrates potential additive effects of TNF-alpha responses induced by adenovirus and other inflammatory signals, and suggests that the response can be mitigated by relative adenovirus particle dose or by inhibitors, such as TNF-binding protein or interleukin 10.

67 – Cytokine Biology

Cytokine biology is infiltrating all aspects of surgical science, as it becomes evident that these mediators are intimately involved in the inflammatory response. With the current sequencing of the human genome, the number of cytokines discovered has increased dramatically. Immunoadhesins and antibodies are two examples of anticytokine-based therapies. The study of cytokine biology has also revealed how some cytokines can counteract the action of other cytokines. This takes advantage of the property that the synthesis of most proinflammatory cytokines is tightly regulated at the level of gene transcription, and they often induce the synthesis of other cytokines that act in an allosteric manner to suppress their synthesis. With the recent explosion in the number of identified cytokines, it is recognized that cytokines can rarely be classified according to their biological function. Rather, most cytokines have overlapping, pleiotropic biologic activities, dependent on what other cytokines and mediators are present in the milieu at that time. What is generally agreed on, however, is that cytokines are protein messengers that convey information among and within cells via specific receptor molecules. Furthermore, cytokines signal to immune and somatic tissues the presence of inflammation, and in doing so, regulate key components of the innate and acquired immune responses. Cytokine signaling can occur in an endocrine, paracrine, autocrine, and juxtacrine fashion, dependent on the cytokine and the current environment in which the cytokine is produced. This is an important consideration when attempting to measure cytokines in biologic fluids, such as the blood, bronchoalveolar lavage, or cerebrospinal fluid.

Emerging Evidence of a More Complex Role for Proinflammatory and Antiinflammatory Cytokines in the Sepsis Response

Since the original discovery and cloning of tumor necrosis factor-α (TNFα) and interleukin-1 (IL-1), our understanding of the underlying role that these and other cytokines play in the sepsis response has greatly evolved.The original concept that the sepsis response is a result of a linear cytokine cascade induced by TNFα and IL-1 has given way to the appreciation that sepsis syndromes often result from a more complex interplay between proinflammatory cytokines, antiinflammatory cytokines, and cytokine antagonists. The proinflammatory cytokine-dominated, systemic inflammatory response syndrome is likely an episodic or transient occurrence; and many septic patients present with a compensatory antiinflammatory cytokine response dominated by the release of antiinflammatory cytokines and cytokine antagonists, leading to immune suppression. There is also growing appreciation that other members of the TNFα superfamily, including Fas ligand (FasL) and glucocorticoids, play an increasingly important role in the loss of immune cells during sepsis through apoptotic processes. The cytokine component of the innate immune response to sepsis plays a complex role not only in the inflammatory response syndrome but also in determining the nature and magnitude of the acquired immune response.