Gene expression profiling of inflammatory bladder disorders

Inflammation underlies all major bladder pathologies including malignancy and represents a defense reaction to injury caused by physical damage, chemical substances, micro-organisms or other agents. During acute inflammation, activation of specific molecular pathways leads to an increased expression of selected genes whose products attack the insult, but ultimately should protect the tissue from the noxious stimulus. However, once the stimulus ceases, gene-expression should return to basal levels to avoid tissue damage, fibrosis, loss of function, and chronic inflammation. If this down-regulation does not occur, tissue fibrosis occurs as a serious complication of chronic inflammation. Although sensory nerve and most cells products are known to be key parts of the inflammatory puzzle, other key molecules are constantly being described that have a role in bladder inflammation. Therefore, as the database describing the repertoire of inflammatory mediators implicated in bladder inflammation increases, the central mechanisms by which injury can induce inflammation, cell damage, and repair often becomes less rather than more clear. To make sense of the vast knowledge of the genes involved in the inflammatory response may require analysis of the patterns of change and the elucidation of gene networks far more than definition of additional members of inflammatory cascades. This review discuss the appropriate use of microarray technology, which promises to solve both of these problems as well as identifying key molecules and mechanisms involved in the transition between acute and chronic inflammation.     

Kinetic study of the inflammatory response in Streptococcus pneumoniae experimental pneumonia treated with the ketolide HMR 3004

Patients still die from Streptococcus pneumoniae pneumonia after initiation of antibiotic therapy, when tissues are sterile and the pneumonia is clearing. There is growing evidence that overwhelming inflammation resulting from toxin release contributes to tissue injury, shock, and death. Monitoring host response may help us understand the consequences of antibiotic therapy for the inflammatory processes that occur in bacterial pneumonia. HMR 3004 is a ketolide that displays excellent in vitro activity against S. pneumoniae. In the present experiment, we investigated the chronology of inflammatory events that occur during pneumococcal pneumonia in mice treated with HMR 3004. Infection of mice with 10(7) CFU of living S. pneumoniae resulted in 100% mortality within 5 days. HMR 3004 given at 12.5 mg/kg of body weight/dose twice daily from 48 h postinfection achieved complete bacterial clearance from lungs and blood within 36 h and ensured survival of mice. Recruitment of neutrophils and monocytes from blood to lungs was significantly reduced, and nitric oxide release was totally prevented. Interleukin-6 secretion in lungs and blood became rapidly undetectable after initiation of therapy. Histological examination of lung tissue showed protection of interstitium against edema. By controlling bacterial invasion, HMR 3004 led to rapid and profound modifications of the host response in lungs, which may protect mice from deleterious inflammatory reactions.     

Supernatant of traumatized muscle induces inflammation and pain, but not microcirculatory perfusion failure and apoptotic cell death

Soft tissue trauma induces an inflammatory response locally and in remote organs. Although remote organ failure is attributed to the systemic action of locally released mediators, it is so far unclear to what extent a direct cell injury and the consequences of ischemia or a secondary injury due to locally released mediators contribute to the manifestation of tissue damage at the primary site of trauma. Soft tissue trauma was induced by means of a controlled impact injury technique in the hind limb of pentobarbital-anesthetized rats. Additional animals received a femoral arterial infusion of supernatant of traumatized muscle tissue, of nontraumatized muscle, or 0.9% NaCl. Tissue injury was assessed by determining microcirculatory perfusion failure, inflammatory response, apoptotic cell death, and nociceptive pain behavior. Muscle tissue of traumatized animals revealed perfusion failure, tissue hypoxia, and inflammation. Nociceptive testing showed a decrease in mechanical pain thresholds of the affected hind paw. Infusion of supernatant of traumatized tissue induced local inflammation and pain comparable with that of directly traumatized tissue; however, it failed to cause nutritive perfusion failure. Supernatant of nontraumatized muscle did not affect muscle microcirculation and integrity. Only animals that underwent direct trauma presented with apoptotic cell death, as given by in vivo fluorescence microscopy, caspase 3 protein cleavage, and transferase-mediated dUTP nick-end labeling histology. Trauma-associated humoral factors cause post-traumatic hyperalgesia and inflammation, but not microvascular perfusion failure and apoptotic cell death. This finding may prompt future efforts in the therapy of closed soft tissue trauma to focus not only on antimediator strategies, but to add regimens targeting perfusion failure and tissue apoptosis.     

Pathophysiology and diagnostic value of urinary trypsin inhibitors.

Inflammation is an important indicator of tissue injury. In the acute form, there is usually accumulation of fluids and plasma components in the affected tissues. Platelet activation and the appearance in blood of abnormally increased numbers of polymorphonucleocytes, lymphocytes, plasma cells and macrophages usually occur. Infectious disorders such as sepsis, meningitis, respiratory infection, urinary tract infection, viral infection, and bacterial infection usually induce an inflammatory response. Chronic inflammation is often associated with diabetes mellitus, acute myocardial infarction, coronary artery disease, kidney diseases, and certain auto-immune disorders, such as rheumatoid arthritis, organ failures and other disorders with an inflammatory component or etiology. The disorder may occur before inflammation is apparent. Markers of inflammation such as C-reactive protein (CRP) and urinary trypsin inhibitors have changed our appraisal of acute events such as myocardial infarction; the infarct may be a response to acute infection and (or) inflammation. We describe here the pathophysiology of an anti-inflammatory agent termed urinary trypsin inhibitor (uTi). It is an important anti-inflammatory substance that is present in urine, blood and all organs. We also describe the anti-inflammatory agent bikunin, a selective inhibitor of serine proteases. The latter are important in modulating inflammatory events and even shutting them down.     

Resolution of acute inflammation and the role of apoptosis in the tissue fate of granulocytes.

We have identified a pathway for granulocyte removal in tissues which is controlled by apoptosis. This process can be modulated by agents in the inflammatory microenvironment and leads to loss of neutrophil secretory function and its phagocytosis by macrophages which utilize a novel recognition mechanism such that the macrophage does not release pro-inflammatory mediators. It is hypothesized that this represents an alternative fate to necrosis, and one which would tend to limit tissue injury and promote inflammatory resolution. This is not to suggest that granulocyte necrosis does not occur; even at sites of 'beneficial inflammation' some necrotic neutrophils may be seen. However, since the development of inflammatory disease is currently thought to result from a multifactoral, quantitative imbalance between potentially injurious inflammatory influences and tissue defences, it is reasonable to suggest that the balance between neutrophil apoptosis and necrosis could represent one of several possible pivotal points in the control of inflammation. Finally, as the specific trigger and induction processes which permit closely related cells to undergo apoptosis at markedly different rates are uncovered, it may be possible to design new anti-inflammatory therapeutic strategies directed towards causing specific cell types to 'commit suicide' and to be cleared by the mechanisms which 'nature intended'. Thus we have begun to dissect the cellular events occurring in the resolution of acute inflammation. We believe that the rapid cessation of neutrophil emigration which occurs remarkably early in the evolution of the acute inflammatory response represents one of the earliest events in the resolution process. Clearly there is much work to be done on the underlying mechanisms. These are likely to be more accessible with the recent molecular characterization of chemotactic cytokines and surface molecules involved in neutrophil-endothelial adhesion transmigration events. It is also clear that apoptosis, which represents an alternative tissue injury-limiting fate to necrosis in situ, may be important in limiting tissue injury and determining whether inflammation persists or resolves. It is also possible that there are circumstances in which the macrophage recognition and clearance of apoptotic neutrophils is impaired. However, a second glance at the events which must occur during the resolution of even the simplest model of acute inflammation (Fig. 1) is sufficient reminder that the 'surface has barely been scratched'. There remain many obscure areas, not the least of which is the fate of the inflammatory macrophage after it has completed its scavenging functions.     

Complement mediators in ischemia-reperfusion injury

BACKGROUND: Ischemia-reperfusion (I/R) injury occurs when a tissue is temporarily deprived of blood supply and the return of the blood supply triggers an intense inflammatory response. Pathologically, increased complement activity can cause substantial damage to blood vessels, tissues and also facilitate leukocyte activation and recruitment following I/R injury. Herein, previously published studies are reported and critically reviewed. METHODS: Medline and the World Wide Web were searched and the relevant literature was classified under the following categories: (1) Complement pathways; (2) The complement system and the inflammatory response; (3) Complement in ischemia-reperfusion injuries; and (4) Therapeutic approaches against complement in I/R injuries. RESULTS AND CONCLUSIONS: I/R injury is a common clinical event with the potential to seriously affect, and sometimes kill, the patient and is a potent inducer of complement activation that results in the production of a number of inflammatory mediators. Complement activation leads to the release of biologically active potent inflammatory complement substances including the anaphylatoxins (C3a and C5a) and the cytolytic terminal membrane attack complement complex C5b-9 (MAC). The use of specific complement inhibitors to block complement activation at various levels of the cascade has been shown to prevent or reduce local tissue injury after I/R. Several agents that inhibit all or part of the complement system, such as soluble complement receptor type 1 (sCR1), C1 inhibitor (C1-INH), C5a monoclonal antibodies, a C5a receptor antagonist and soluble CD59 (sCD59) have been shown to reduce I/R injury of various organs. The novel inhibitors of complement products may eventually find wide clinical application because there are no effective drug therapies currently available to treat I/R injuries.     

Resolvins and omega three polyunsaturated fatty acids: Clinical implications in inflammatory diseases and cancer

Inflammation is a central process in several disorders and contributes to cancer progression. Inflammation involves a complex cascade of pro-inflammatory and anti-inflammatory signaling events with protein and lipid mediators. Recent advances in lipid detection have revealed the importance of lipid mediators in inflammation. Omega three polyunsaturated fatty acids (ω-3 PUFA) are found naturally in fish oil and have been extensively studied in multiple inflammatory diseases with improved outcomes. Resolvins are thought to be the active metabolites of ω-3 PUFA, and are responsible for facilitating the resolving phase of acute inflammation. Clinically, resolvins have been associated with resolution of acute kidney injury and acute lung injury, micro and macro vascular response to injury, and inhibition of microglia-activated inflammation in neurodegenerative disorders. In addition to inflammatory diseases, ω-3 PUFA and resolvins appear to modulate cancer progression. ω-3 PUFA intake has been associated with reduced inflammation in colorectal cancer, and favorable phenotype in breast cancer. Resolvins offer promising therapeutic potential as they may modulate inflammation with minimal side-effects, in contrast to currently available anti-inflammatory medications. This review describes the roles of ω-3 PUFA and resolvins in the inflammatory cascade, various inflammatory diseases, and specific cancers. Additionally, it will discuss the clinical therapeutic potential of resolvins as targets in inflammatory diseases and cancers.     

Leucocyte activation markers in clinical practice.

The response against tissue injury and infection begins with the early activation of molecular and cellular elements of the inflammatory and immune response. Severe tissue injury, necrosis, and infection induce imbalanced inflammation associated with leukocyte over-stimulation and excessive or dysregulated release of cellular mediators. Clinical and experimental studies have shown that these mediators are directly related to progressive post-injury complications. Persistent increased levels of pro-inflammatory mediators produce tissue injury. Excessive production and activity of anti-inflammatory mediators cause anergy and/or immune dysfunction with increased susceptibility to infection. Leukocyte activation is assessed by cell surface phenotype expression, cellular mediators determination, or by measuring functional responses using isolated cells. Potential routine clinical uses are: evaluation of severity and prognosis in critically ill patients, immunomonitoring of sepsis, and detection of tissue injury, necrosis, and infection. In practice, the determination of cellular activation markers is restricted by a limited number of automated methods and by the cost of reagents. The availability of flow cytometry and immunoassay automated systems can contribute to a wider use in practice. Here we review the immunopathophysiology of polymorphonuclear neutrophil, monocyte, macrophage, and lymphocyte activation in response to tissue injury and infection. In addition, laboratory methods for their determination, and clinical applications in practice, are discussed.     

A primer in cytokines

The host response to injury or infection is a complex interplay of endocrine, metabolic, and immunological alterations designed to promote wound healing and restore the system to a state of homeostasis. Cytokines are the primary mediators of the inflammatory response to injury. This article serves as an introduction to this important class of inflammatory mediators. The major pro- and anti-inflammatory cytokines as well as the chemokines are discussed. Results from laboratory and clinical attempts at manipulation of these mediators are discussed and recommendations for future research in anticytokine therapy are made.     

Trauma: the acute response

Moderate to severe trauma is followed by a local response, which involves changes in cell function and an inflammatory reaction, and a systemic response coordinated by the nervous and endocrine systems. Early post-trauma alterations in cells are due primarily to decreased oxygen supply and include 1) the shifting of electrolytes and water, either into or out of cells, and 2) the production or release of various local tissue factors. These tissue factors produce changes in blood flow, increased vascular permeability, and other local manifestations of inflammation. Trauma activates nervous and hormonal pathways which help to restore blood volume and maintain the function of essential organs. The effects of these responses on cellular oxygen consumption and body temperature are described. Examples of respiratory system involvement in response to trauma in the lungs or elsewhere are given. These include increased capillary permeability in the lungs, pulmonary emboli, and damage from smoke and heat inhalation.     

Neutrophil oxygen radical generation. Synergistic responses to tumor necrosis factor and mono/polyunsaturated fatty acids.

In inflammatory reactions there are complex interactions of protein mediators (cytokines) and mediators derived from lipids. An important event in inflammation is superoxide production, in relation to microbicidal activity as well as tissue damage. We have studied interactions of lipid mediators with a cytokine mediator tumor necrosis factor alpha (TNF) in stimulating superoxide production by human neutrophils for this reason and because it throws light on intracellular signals activating this response. Pretreatment of neutrophils with TNF markedly augmented the amount of superoxide produced in response to AA but not to either a 20 carbon saturated fatty acid, or the hydroxy- or hydroperoxy-derivatives of AA. Not only were other polyunsaturated fatty acids (eicosapentanoic, docosahexaenoic, linolenic, linoleic acid) as effective as AA but so was the monounsaturated fatty acid, oleic acid. Indeed TNF primed the neutrophils for an increased response to a major mediator of inflammation, leukotriene B4, which is a product of AA metabolism via the lipoxygenase pathway. The data demonstrate that two major types of mediators generated during an inflammatory response have synergistic action on neutrophils in the generation of reactive oxygen species. In contrast, neutrophils primed with TNF and challenged with PGE2, a product of AA metabolism via the cyclooxygenase pathway, showed a reduced chemiluminescence response. This identifies an important interaction between unsaturated lipids and cytokines which is likely to play a critical role in disease processes and nutrient modulation of the immune responses.     

Translational systems biology: introduction of an engineering approach to the pathophysiology of the burn patient.

The pathophysiology of the burn patient manifests the full spectrum of the complexity of the inflammatory response. In the acute phase, inflammation may have negative effects via capillary leak, the propagation of inhalation injury, and development of multiple organ failure. Attempts to mediate these processes remain a central subject of burn care research. Conversely, inflammation is a necessary prologue and component in the later stage processes of wound healing. Despite the volume of information concerning the cellular and molecular processes involved in inflammation, there exists a significant gap between the knowledge of mechanistic pathophysiology and the development of effective clinical therapeutic regimens. Translational systems biology (TSB) is the application of dynamic mathematical modeling and certain engineering principles to biological systems to integrate mechanism with phenomenon and, importantly, to revise clinical practice. This study will review the existing applications of TSB in the areas of inflammation and wound healing, relate them to specific areas of interest to the burn community, and present an integrated framework that links TSB with traditional burn research.     

Novel regenerative strategies to enhance periodontal therapy outcome

Background: Chronic periodontitis is a widely prevalent inflammatory condition of the supporting tissues of the teeth and is characterized by loss of teeth with an associated risk of systemic complications. Regenerative therapies such as guided tissue and bone regeneration form an important armamentarium in periodontics with a high degree of outcome predictability in certain ideal clinical scenarios. Objective/methods: This review elaborates novel tissue regenerative treatment modalities based on sound understanding of developmental biology, tissue engineering, inflammation and wound healing. We focus on the role of biological mediators such as growth factors, gene-based therapy, cell therapy and pro-resolution lipid mediators in the regeneration of lost bone or periodontium. Results/conclusions: These therapies have the potential to regenerate both periodontium and bone, aiding in the treatment of even clinically challenging cases.     

Multiple organ failure syndrome.

Tissue injury, whether from infection, blood or volume loss, trauma, or inflammation such as pancreatitis, induces local and systemic responses. The systemic responses include shock, reperfusion, systemic inflammation (hypermetabolism) with primary organ dysfunction, and secondary organ dysfunction that either becomes progressive and leads to death or from which the patient recovers and enters into a period of prolonged rehabilitation. Each of these responses has its pathogenesis and treatments that are appropriate and effective. The research indicates that the responses may contribute to the development of cell and organ injury and to progressive multiple organ failure syndrome and death, particularly in the case of the systemic inflammatory response. Current therapy is designed to rapidly remove the cause of injury, resuscitate the microcirculation, and institute nutrition therapy to prevent single and generalized nutrient deficiencies and promote repair and healing. Newer therapies are designed to modulate the inflammatory response itself to minimize its injury potential and promote tissue repair and recovery of the patient. Genetic regulation of metabolism is also a pathogenetic mechanism. Its role in these responses is just starting to be understood--new therapies will need to await this understanding. Once the patient begins to recover, rehabilitation tends to be long and problematic. Nonetheless, significant survival rates are now occurring, with continued improvements expected in response to the newer therapeutic approaches. Planned rehabilitation thus becomes an important component of effective recovery. Professionals trained in critical care and well versed in cellular and molecular biology provide the milieu within which continued improvements in prevention, therapy, and outcome will continue to occur.     

A novel inhibitory peptide of Toll-like receptor signaling limits lipopolysaccharide-induced production of inflammatory mediators and enhances survival in mice

Sepsis resulting from gram-negative bacterial infections is characterized by an excessive inflammatory immune response initiated by exposure of the host innate immune system to either bacteria or bacterial products, primarily lipopolysaccharide (LPS). Engagement of the Toll-like receptor (TLR) 4 on immune cells by LPS induces production of inflammatory mediators, leading to tissue damage. We recently identified a peptide, termed P13, which was previously shown to be a potent inhibitor of in vitro TLR signaling. In this study, we demonstrate that the use of this novel peptide significantly reduces the in vitro production of inflammatory mediators seen after exposure of hepatocytes/nonparenchymal cell cocultures and endothelial cells to LPS. In addition, in vivo treatment of mice with this peptide was effective at inhibiting LPS-induced production of inflammatory mediators and significantly limited liver damage. Peptide treatment significantly increased survival of LPS-/D-galactosamine-treated mice and mice treated with high-dose LPS. These results demonstrated the therapeutic potential of peptide P13 to limit an LPS-induced inflammatory response and enhance survival in murine models of inflammation.     

Conventional DCs reduce liver ischemia/reperfusion injury in mice via IL-10 secretion

TLRs are recognized as promoters of tissue damage, even in the absence of pathogens. TLR binding to damage-associated molecular patterns (DAMPs) released by injured host cells unleashes an inflammatory cascade that amplifies tissue destruction. However, whether TLRs possess the reciprocal ability to curtail the extent of sterile inflammation is uncertain. Here, we investigated this possibility in mice by studying the role of conventional DCs (cDCs) in liver ischemia/reperfusion (I/R) injury, a model of sterile inflammation. Targeted depletion of mouse cDCs increased liver injury after I/R, as assessed by serum alanine aminotransferase and histologic analysis. In vitro, we identified hepatocyte DNA as an endogenous ligand to TLR9 that promoted cDCs to secrete IL-10. In vivo, cDC production of IL-10 required TLR9 and reduced liver injury. In addition, we found that inflammatory monocytes recruited to the liver via chemokine receptor 2 were downstream targets of cDC IL-10. IL-10 from cDCs reduced production of TNF, IL-6, and ROS by inflammatory monocytes. Our results implicate inflammatory monocytes as mediators of liver I/R injury and reveal that cDCs respond to DAMPS during sterile inflammation, providing the host with protection from progressive tissue damage.