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Genetic and epigenetic factors that predispose to ineffective control of subgingival biofilm composition are incompletely understood. The objective of this study was to elucidate how leukocytes impact on the course of periodontitis in Rac-null mice. Models of acute gingivitis and periodontitis were used to assess the early inflammatory response and patterns of chronicity leading to alveolar bone loss. Leukocyte margination was differentially impaired during attachment in conditional Rac1-null and during rolling and attachment in Rac2-null mice. The inflammatory responses to subgingival ligatures were altered in Rac-null compared to WT mice. In response to persistent subgingival challenge Rac-null mice had increased alveolar bone loss with resorption patterns characteristic to aggressive periodontitis, partially explained by higher osteoclastic activity in Rac-null mice. This study demonstrates that migratory leukocyte defects are rate limiting steps in the periodontal inflammatory process that lead to more aggressive forms of periodontitis.

Genetic and epigenetic factors that predispose to ineffective control of subgingival biofilm composition are incompletely understood. The objective of this study was to elucidate how leukocytes impact on the course of periodontitis in Rac-null mice. Models of acute gingivitis and periodontitis were used to assess the early inflammatory response and patterns of chronicity leading to alveolar bone loss. Leukocyte margination was differentially impaired during attachment in conditional Rac1-null and during rolling and attachment in Rac2-null mice. The inflammatory responses to subgingival ligatures were altered in Rac-null compared to WT mice. In response to persistent subgingival challenge Rac-null mice had increased alveolar bone loss with resorption patterns characteristic to aggressive periodontitis, partially explained by higher osteoclastic activity in Rac-null mice. This study demonstrates that migratory leukocyte defects are rate limiting steps in the periodontal inflammatory process that lead to more aggressive forms of periodontitis.

Neutrophil granulocytes constitute the front line of defense in the innate immune response to invading microorganisms, but can also contribute to development of inflammatory disease and tissue destruction following e.g. myocardial infarction or stroke. During inflammatory activation, neutrophils leave the blood, interact with extracellular matrix proteins, and migrate into tissues in response to chemotactic factors to phagocytose and kill infectious agents by using toxic granule contents and reactive oxygen metabolites. The functional neutrophil response relies on exocytosis of cytoplasmic granules, each containing membrane proteins, which are thereby mobilized to the plasma membrane. Specific programmed cell death (apoptotic) pathways regulate neutrophil homeostasis, where an inflammatory milieu can prolong the life span of neutrophils to several days, whereas non-activated neutrophils are committed to constitutive/spontaneous apoptosis within hours. Signal regulatory protein alpha (SIRPα) is a surface glycoprotein with two intracellular immunoreceptor-tyrosine-based inhibitory motifs (ITIMs), which is highly expressed in neutrophils and other myeloid cells. In other cell types, SIRPα has been shown to regulate cellular functions such as cell migration and phagocytosis. The aim of the present thesis was to investigate neutrophil SIRPα expression in response to inflammatory activation or apoptosis, and how this receptor can regulate neutrophil adhesion and cell migration. Neutrophils contain several subcellular granule compartments, including primary (azurophilic), secondary (specific), tertiary (gelatinase) granules, and a fourth compartment called secretory vesicles. In resting neutrophils, SIRPα was found to be present in the plasma membrane and in all types of granules except for the azurophilic granules. Stimulation with the bacterial peptide fMLF in vitro, or inflammatory activation in vivo, was found to rapidly mobilize SIRPα to the neutrophil cell surface. In mice expressing a mutated form of SIRPα, where the cytoplasmic signaling domain was deleted, we found an enhanced accumulation of neutrophils in the peritoneal cavity in a peritonitis model. These findings therefore suggest that an increased amount of SIRPα on the surface of activated neutrophils could serve to negatively fine-tune neutrophil accumulation in inflammation. Neutrophil priming means that the cell becomes partially activated, in a way that facilitates subsequent full activation. One part of the priming process is a moderate exocytosis of granules, mostly the secretory vesicles, which increases the density of certain receptors on the cell surface. It also involves the activation of adhesion receptors called integrins. We found that TNFα-induced priming involved an increased accumulation of SIRPα on the cell surface. When comparing wild-type and SIRPα-mutant neutrophils, we found a strongly reduced TNFα-stimulated and β2 integrin-dependent adhesion of mutant neutrophils to type I collagen or fibrinogen. This adhesion defect resulted in a reduced adhesion-dependent activation of the respiratory burst and an increased chemotactic response of SIRPα-mutant neutrophils in vitro. During neutrophil apoptosis, several receptors are known to be shed from the cell surface (e.g. CD16 and CD43). We found that also SIRPα is shed from the surface during spontaneous as well as Fas-induced apoptosis. The shedding mechanism was found to involve matrix metalloproteinase (MMP) activity, mostly that of MMP-3 and MMP-8. In conclusion, neutrophil cell surface SIRPα expression is regulated during neutrophil activation and seems to play an important role in stimulating β2-integrin-dependent adhesion. This way, SIRPα can negatively fine-tune neutrophil migration and accumulation in inflammation. During apoptosis, SIRPα is shed from the cell surface, which may be one mechanism contributing to the well-known down-regulation in the adhesiveness of apoptotic neutrophils.

Absence of stearoyl-CoA desaturase-1 (SCD1) in mice leads to chronic inflammation of the skin and increased susceptibility to atherosclerosis, while also increasing plasma inflammatory markers. A recent report suggested that SCD1 deficiency also increases disease severity in a mouse model of inflammatory bowel disease, induced by dextran sulfate sodium (DSS). However, SCD1-deficient mice are known to consume increased amounts of water, which would also be expected to increase the intake of DSS-treated water. The aim of this study was to determine the effect of SCD1 deficiency on DSS-induced acute colitis with DSS dosing adjusted to account for genotype differences in fluid consumption. Wild-type controls were treated with 3.5% DSS for 5 days to induce moderately severe colitis, while the concentration of DSS given to SCD1-deficient mice was lowered to 2.5% to control for increased fluid consumption. Colonic inflammation was assessed by clinical and histological scoring. Although SCD1-deficient mice consumed a total intake of DSS that was greater than that of wild-type controls, colonic inflammation, colon length and fecal blood were not altered by SCD1-deficiency in DSS-induced colitis, while diarrhea and total weight loss were modestly improved. Despite SCD1 deficiency leading to chronic inflammation of the skin and increased susceptibility to atherosclerosis, it does not accelerate inflammation in the DSS-induced model of acute colitis when DSS intake is controlled. These observations suggest that SCD1 deficiency does not play a significant role in colonic inflammation in this model. [The original version of this article, along with updated information and services is located on the World Wide Web at: http://dx.doi.org/10.1016/j.bbalip.2009.08.001]

Cerebral ischemia and intracerebral hemorrhage (ICH) are both characterized by a prolonged inflammatory response and secondary injury phase, yet the spatial/temporal relationships between inflammation and white matter (WM) damage were largely unknown. Thus, I quantified the development of WM damage and inflammation over 7 days after ischemia, and 14 days after ICH. Following ischemia, myelin and axons were progressively damaged, and myelin damage coincided with neutrophil infiltration. Activated microglia/macrophages increased dramatically in the lesion core and edge, and selectively infiltrated damaged WM tracts while surrounding undamaged ones. To investigate the involvement of neutrophils in WM damage and inflammation after ICH, rats were rendered neutropenic before performing ICH. Neutrophil depletion reduced peri-hematomal axonal damage, BBB breakdown, and MMP-9 production at early times, and lessened microglia/macrophage and astrocyte responses at later times. Activated microglia/macrophages infiltrated peri-hematomal WM tracts, correlating with myelin fragmentation and axonal loss, and this was reduced with neutrophil depletion.

The last decade has been witness to a number of seminal discoveries in the field of innate immunity. The discovery that microbial molecules and endogenous danger signals can be detected by germ-line encoded receptors has changed the way we study the immune system. Indeed, the characterization of Toll in Drosophila as a sensor of microbial products in 1997 then led to the discovery of a family of Toll Like Receptors (TLRs) in mammals. TLRs are critical for the induction of inflammatory responses and the generation of a successful adaptive immune response. The array of ligands that these transmembrane proteins recognized mediates defense against bacteria, viruses, fungus and parasites, as well as, possibly, cancerous cells. In addition to this membrane-bound family of recognition proteins, two families of pattern recognition receptors have been recently shown to respond to microbial and chemical ligands within the cytosol. These represent the Nod Like Receptors (NLRs) and RIGI-like helicase receptor (RLH) families. Nod1 and Nod2 are members of the NLR family of proteins, which are responsible for the recognition of components derived from the bacterial cell wall, more precisely, moieties of peptidoglycan. As such, Nod1 and Nod2 are implicated in the recognition and the defense against bacterial pathogens. Importantly, the genes encoding these two proteins have also been linked to the etiology of several inflammatory disorders such as Crohn’s disease and asthma. In this thesis, we show that recognition of Nod1 and Nod2 ligands generates a rapid and transient inflammatory response in vivo. When co-injected with a model protein, Nod1 and Nod2 ligands exhibit adjuvant properties that lead to the generation of an antigen-specific Th2 type adaptive immune response. Surprisingly, recognition of the Nod1 ligand in non-hematopoietic cells is critical for the generation of this immune response. In contrast, TLRs classically tip the balance towards a Th1 response and interestingly, co-injection of TLR and Nod ligands synergize to generate a more potent immune response characterized by the generation of Th1, Th2 and Th17 T cell respones. To study the role of Nod1 and Nod2 in the context of a bacterial infection in vivo, we used an intestinal mouse pathogen, Salmonella enterica serovar Typhimurium. We were able to show that Nod1-deficient mice, but not Nod2-deficient mice, are more susceptible to the strain of this bacterium, which enters the host through the active pickup in the intestinal lumen by underlying myeloid cells. This sampling mechanism is mediated by a subset of dendritic cells that populate the intestinal lamina propria. Accordingly, the defect seen in Nod1-deficient mice localizes to the mucosal barrier where these dendritic cells appear to have an impaired response towards the bacteria. Taken together, these results increase our knowledge on the general role of Nod1 and Nod2 in immunity and might generate new avenues of research and potential therapeutic targets.

Cerebral ischemia and intracerebral hemorrhage (ICH) are both characterized by a prolonged inflammatory response and secondary injury phase, yet the spatial/temporal relationships between inflammation and white matter (WM) damage were largely unknown. Thus, I quantified the development of WM damage and inflammation over 7 days after ischemia, and 14 days after ICH. Following ischemia, myelin and axons were progressively damaged, and myelin damage coincided with neutrophil infiltration. Activated microglia/macrophages increased dramatically in the lesion core and edge, and selectively infiltrated damaged WM tracts while surrounding undamaged ones. To investigate the involvement of neutrophils in WM damage and inflammation after ICH, rats were rendered neutropenic before performing ICH. Neutrophil depletion reduced peri-hematomal axonal damage, BBB breakdown, and MMP-9 production at early times, and lessened microglia/macrophage and astrocyte responses at later times. Activated microglia/macrophages infiltrated peri-hematomal WM tracts, correlating with myelin fragmentation and axonal loss, and this was reduced with neutrophil depletion.

Lėtinė obstrukcinė plaučių liga (LOPL) - lėtai progresuojanti kvėpavimo takų obstrukcija, atsirandanti dėl nenormalaus uždegiminio plaučių atsako į žalingas su oru įkvepiamas daleles ar dujas. Tai liga, lemianti didelį sergamumą ir mirtingumą visame pasaulyje. Sergant LOPL labiausiai pažeidžiami apatiniai kvėpavimo takai, o taip pat periferiniame kraujyje nustatomas uždegimo žymenų koncentracijų padidėjimas. Pastarasis rodo, jog vyksta sisteminis uždegimas. Kvėpavimo takų sekretas yra biologinė terpė, kurioje esantys imuniniai žymenys atspindi vietinį uždegimą. Tiek vietinio, tiek ir sisteminio uždegiminio proceso metu pagrindinėmis ląstelėmis įvardijamos neutrofilai. LOPL yra daugiakomponentė liga ir siekiant suprasti šios ligos metu vykstančius įvairius patogeninius mechanizmus, būtina įvertinti vietinį ir sisteminį uždegimą jungiančias jungtis bei principus. Norint nustatyti vietinio ir sisteminio uždegimo sąsajas, svarbu įvertinti kvėpavimo takų sekreto tiesioginį poveikį kraujo neutrofilų funkcijoms. Šio darbo tikslas buvo įvertinti kraujo neutrofilų chemotaktinį ir fagocitinį aktyvumą bei reaktyvių deguonies formų (ROS) susidarymo ypatumus sergant LOPL. Kraujo neutrofilų chemotaksis tirtas aktyvinant neutrofilus klasikiniu chemotaksį skatinančiu veiksniu- interleukinu-8 (IL-8), indukuotais skrepliais bei indukuotais skrepliais papildytais skirtingomis IL-8 koncentracijomis (10, 30, 100 ng/ml). Fagocitinis kraujo neutrofilų aktyvumas bei ROS susidarymas buvo tirtas... [toliau žr. visą tekstą] / Chronic obstructive pulmonary disease (COPD) - slowly progressive airway obstruction resulting from abnormal inflammatory response to lung damaging particles of inhaled air or gas. It is a major cause of high morbidity and moratlity worldwide. Patients with COPD has lung injury, but determined increased blood levels of inflammatory markers shows and systemic inflammation. Neutrophils are the key inflammatory cells both in local and systemic inflammatory process. COPD is heterogeneous disease and in order to understand a variety of pathogenic mechanisms it is necessary to evaluate local and systemic inflammation combination characteristics and principles. It is also important to investigate if airway mucus influence blood neutrophils activity. The aim of this study was to evaluate both chemotactic and phagocytic activity and reactive oxygen species (ROS) production in peripheral blood neutrophils during COPD. Blood neutrophils chemotaxis was measured by activation of the interleukin-8 (IL-8), induced sputum and induced sputum and IL-8 different concentration (10, 30 and 100 ng/ml) combination. Phagocytic activity and ROS generation of blood neutrophils was measured after neutrophils activation with serum osponized/non-osponized S. aureus bacteria, induced sputum and induced sputum combination with S. aureus bacteria. The concentrations of 10, 30 and 100 bact./neutrophil S. aureus were used for all experiments. All features of neutrophils in vitro were analyzed by flow... [to full text]

Epidemiological studies have described a link between chronic inflammatory conditions, such as diabetes or obesity, and EOC suggesting that systemic inflammation may increase the risk of the disease. The purpose of this study was to identify the impact of prolonged exposure to low-grade inflammation on EOC tumorigenicity. We hypothesized that exposure to this inflammation would accelerate ovarian tumor growth. In vitro, normal and transformed ovarian epithelial cells had limited responsiveness to inflammatory cytokines. In vivo, LPS-induced low-grade chronic systemic inflammation accelerated EOC progression primarily through enhanced angiogenesis. Evaluation of the relationships between chronic systemic inflammation and EOC may provide a role for anti-inflammatory treatment in combinational EOC therapies. Additionally, as the rate of metabolic disorders increases in the Western world the results from this work may facilitate the advancement of complimentary therapeutic interventions for other cancers that are influenced by inflammation.