Inhibitory effects of TSG-6 Link module on leukocyte-endothelial cell interactions in vitro and in vivo

OBJECTIVE: The authors investigated whether the anti-inflammatory protein tumor necrosis factor (TNF)-stimulated gene-6 (TSG-6) and its Link module (Link_TSG6) could affect the complex multistep process of leukocyte/endothelial cell (EC) interaction. METHODS: Mouse mesenteries were inflamed with interleukin (IL)-1beta and the extent of leukocyte rolling, adhesion, and emigration was determined after 2 h. Link_TSG6 and a single-point mutant (termed K13E) were given intraperitoneally together with the cytokine. Human neutrophil chemotaxis and transmigration were determined in vitro in response to IL-8 and/or TNF-alpha. TSG-6, Link_TSG6, and K13E were added to the leukocytes or the EC monolayers. RESULTS: Co-injection of Link_TSG6 with IL-1beta selectively inhibited cell flux, adhesion, and emigration as analyzed in mesenteric postcapillary venules. The fewer cells that rolled in the animals treated with Link_TSG6 displayed a velocity similar to that measured in vehicle-treated mice. In vitro, Link_TSG6 did not affect neutrophil chemotaxis or EC activation but did inhibit neutrophil transmigration across EC monolayers. The latter effect was shared by full-length TSG-6 and observed equally in response to IL-8 or TNF-alpha. CONCLUSIONS: These data restrict the site of action for at least some of the anti-inflammatory effects ascribed to TSG-6/Link_TSG6 to the microenvironment of the extravasating leukocyte.     

Ozone production by amino acids contributes to killing of bacteria

Reactive oxygen species produced by phagocytosing neutrophils are essential for innate host defense against invading microbes. Previous observations revealed that antibody-catalyzed ozone formation by human neutrophils contributed to the killing of bacteria. In this study, we discovered that 4 amino acids themselves were able to catalyze the production of an oxidant with the chemical signature of ozone from singlet oxygen in the water-oxidation pathway, at comparable level to antibodies. The resultant oxidant with the chemical signature of ozone exhibited significant bactericidal activity in our distinct cell-free system and in human neutrophils. The results also suggest that an oxidant with the chemical signature of ozone produced by neutrophils might potentiate a host defense system, when the host is challenged by high doses of infectious agents. Our findings provide biological insights into the killing of bacteria by neutrophils.     

Mediator-Directed Therapy in Pancreatitis and Trauma

Both acute pancreatitis and severe trauma induce a systemic sterile inflammatory process which leads to a high incidence of remote organ dysfunction and death. Several attributes of these two entities make them ideal for evaluation of the effects of mediator-directed therapy. The rationale and evidence for mediator-directed therapy in pancreatitis and trauma are reviewed. In pancreatitis, organ dysfunction and death are best prevented using strategies designed to limit the inflammatory response, particularly IL-1a and IL-10. By contrast, the sequelae of a post-traumatic systemic inflammatory response are best mitigated using strategies designed to limit neutrophil adhesion.     

Clinical pertinence of neutrophil-to- lymphocyte ratio among hypertensives with different grades and duration of hypertension – an insight

Over the recent years, the pathophysiology of the inflammatory component in hypertension has been a challenge, because this inflammatory response is mainly contributed by an increased oxidative stress with the release of inflammatory mediators. Identification of a simple and early inflammatory marker such as the neutrophil-to-lymphocyte ratio (NLR) is the need of the hour. This study correlates the same specifically taking into account the duration and the grades of hypertension.

Objective: The response of the NLR among the hypertensives and its correlation with duration and stages of hypertension.

Method: Totally, 80 subjects and 40 controls of age between 20 and 60 years and both genders were included. Three recordings of blood pressure were measured with a standard mercury sphygmomanometer. The differential leukocyte count was estimated with an automated Beckman Coulter.

Objective: Variations in the neutrophil and lymphocyte counts were significant among the hypertensives with a p-value < 0.001. The NLR was also significantly altered among the hypertensives with a p-value = 0.001. The NLR showed a rise in value among the normotensives, prehypertensives, and stage 1 of systolic hypertension, though not statistically significant. An increase in the NLR was observed in hypertensives with duration of 1–2 years.

Conclusion: Our study gives a new insight with a rise in NLR in early years and even among prehypertensives and stage 1 systolic hypertension under strict criterion. This could be utilized as an early predictive tool, relating the inflammatory process and hypertension which on further intervention could slow the progression of the disease process.

Abbreviations: NLR: Neutrophil-to-lymphocyte ratio; BP: Blood pressure.     

G-CSF: A key regulator of neutrophil production,but that's not all!

G-CSF is a major extracellular regulator of haemopoiesis and the innate immune system. Named for its relatively specific stimulation of the growth of neutrophil progenitor cells in vitro in semi-solid cultures (Burgess and Metcalf 1980, Nicola et al. 1983), G-CSF influences the survival, proliferation and differentiation of all cells in the neutrophil lineage, from haemopoietic stem cell through to mature neutrophil. Further, G-CSF influences the function of mature neutrophils. These actions underpin its rapid uptake into clinical medicine as a drug that increases the production of neutrophils in patients with chemotherapy-induced neutropenia.

Ongoing research has uncovered initially unsuspected polyfunctionality for G-CSF. G-CSF is well recognised as a potent mobiliser of haemopoietic stem cells from the bone marrow into the blood, and now is being increasingly accepted as a regulator of immune responses. These two “new” actions of G-CSF first came to light through observations made during clinical trials of G-CSF. Subsequent investigations into the cellular and molecular basis for this polyfunctionality have generated exciting new knowledge about the biology of G-CSF. This review emphasises recent advances in knowledge about G-CSF signalling, mechanisms of G-CSF-induced stem cell mobilisation, and how G-CSF influences T-cell function and dendritic cell activation. An attempt is made to link the current issues about the biology of G-CSF with its clinical uses, both present and future.     

Neutropenia and Primary Immunodeficiency Diseases

Primary immunodeficiency diseases (PID) are a heterogeneous group of congenital disorders of the immune system leading to recurrent infections, autoimmunity, malignancies, and hematological disorders. This review focuses specifically on inherited disorders associated with neutropenia, which may occur in isolation or as a feature of more complex immune disorders. It has been known for a long time that defined immunodeficiency syndromes, such as CD40L deficiency, WHIM syndrome, or Chédiak Higashi syndrome, may be associated with neutropenia even though the mechanisms are poorly understood. In some PID, neutropenia may result from chronic viral infection or from autoimmunity. Recently, the identification of several novel genetic defects (e.g., p14-deficiency, HAX1-deficiency, AK2-deficiency) has shed light on the pathophysiology of congenital neutropenia. This review summarizes the clinical, immunological, and genetic features of congenital neutropenia syndromes.     

Imaging of muscle activity-induced morphometric changes in fibril network of myofascia by two-photon microscopy

Myofascia, deep fascia enveloping skeletal muscles, consists of abundant collagen and elastin fibres that play a key role in the transmission of muscular forces. However, understanding of biomechanical dynamics in myofascia remains very limited due to less quantitative and relevant approaches for in vivo examination. The purpose of this study was to evaluate the myofascial fibril structure by means of a quantitative approach using two-photon microscopy (TPM) imaging in combination with intravital staining of Evans blue dye (EBD), a far-red fluorescence dye, which potentially labels elastin. With focus on myofascia of the tibial anterior (TA) muscle, the fibril structure intravitally stained with EBD was observed at the depth level of collagen fibrous membrane above the muscle belly. The EBD-labelled fibril structure and orientation in myofascia indicated biomechanical responses to muscle activity and ageing. The orientation histograms of EBD-labelled fibrils were significantly modified depending upon the intensity of muscle activity and ageing. Moreover, the density of EBD-labelled fibrils in myofascia decreased with habitual exercise but increased with muscle immobilization or ageing. In particular, the diameter of EBD-labelled fibrils in aged mice was significantly higher. The orientation histograms of EBD-labelled fibrils after habitual exercise, muscle immobilization and ageing showed significant differences compared to control. Indeed, the histograms in bilateral TA myofascia of exercise mice made simple waveforms without multiple sharp peaks, whilst muscular immobilization or ageing significantly shifted a histogram with sustaining multiple sharp peaks. Therefore, the dynamics of fibre network with EBD fluorescence in response to the biomechanical environment possibly indicate functional tissue adaptation in myofascia. Furthermore, on the basis of the knowledge that neutrophil recruitment occurs locally in working muscles, we suggested the unique reconstruction mechanism involving neutrophilic elastase in the myofascial fibril structure. In addition to the elastolytic susceptibility of EBD-labelled fibrils, distinct immunoreactivities and activities of neutrophil elastase in the myofascia were observed after electric pulse stimulation-induced muscle contraction for 15 min. Our findings of EBD-labelled fibril dynamics in myofascia through quantitative approach using TPM imaging and intravital fluorescence labelling potentially brings new insights to examine muscle physiology and pathology.