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Abstract: Killer Ig-like receptors (KIRs) are MHC class I-specific receptors expressed by Natural Killer (NK) and T cell subsets. KIRs either inhibit (KIR-L) or activate (KIR-S) lymphocyte functions. Inhibitory KIR2DL1 and activating KIR2DS1 share ligand specificity for the HLA-C2 group, consistent with their almost identical extracytoplasmic domain. This homology hampered the distinction between KIR2DL1 and KIR2DS1. We report here the characterization of the KIR2DS1+ subsets among primary human NK and T cells. Regardless of the host HLA-C genotype, around 10% of circulating NK cells expressed KIR2DS1 in absence of KIR2DL1. In HLA-C2 individuals, KIR2DS1 was not able to induce NK cell education (i.e., the acquisition of NK cell competence) nor to interfere with KIR2DL1-induced NK cell education. KIR2DS1 was also present on rare oligoclonal TCRαβ+CD8α+ and TCRαβ+CD4−CD8− subsets. As KIR2DS1 has been associated with autoimmunity and hematopoietic stem cell transplantation, these results pave the way to dissect the function of KIR2DS1 in these clinical conditions. [Copyright &y& Elsevier]

Background: Fibroproliferative repair phase of the acute respiratory distress syndrome (ARDS) is followed by a restitutio ad integrum of lung parenchyma or by an irreversible lung fibrosis and patients’ death. Transforming Growth Factor-β1 (TGF-β1) is involved in collagen production and lung repair. We investigated whether alveolar TGF-β1 was associated with the presence of fibroproliferation and the outcome of ARDS patients. Methods: Sixty-two patients were included the first day of moderate-to-severe ARDS. Bronchoalveolar lavage fluid (BALF) was collected at day 3 (and day 7 when the patients were still receiving invasive mechanical ventilation) from the onset of ARDS. Survival was evaluated at day 60. TGF-β1 was measured by immunoassay. The patients were classified as having lung fibroproliferation when the alveolar N-terminal peptide for type III procollagen (NT-PCP-III) measured on day 3 was > 9 μg/L as recently reported. The main objective of this study was to compare the alveolar levels of total TGF-β1 according to the presence or not a lung fibroproliferation at day 3. Results: Forty-three patients (30.6%) presented a fibroproliferation at day 3. BALF levels of total TGF-β1 were not statistically different at day 3 (and at day 7) according to the presence or not lung fibroproliferation. Mortality at day 60 was higher in the group of patients with fibroproliferation as compared with patients with no fibroproliferation (68.4% vs. 18.6% respectively; p < 0.001). Total TGF-β1 measured on BALF at day 3 was not associated with the outcome. Multiple logistic regression showed that the presence of lung fibroproliferation was associated with death. In contrast, TGF-β1 was not independently associated with death. Conclusions: Pulmonary levels of TGF-β1 during the first week of ARDS were not associated nor with the presence of fibroproliferation neither with death. TGF-β1 should not be used as a biomarker to direct anti-fibrotic therapies. [ABSTRACT FROM AUTHOR]

Leukocyte adhesion deficiency type III is a recently described condition involving a Glanzmann-type bleeding syndrome and leukocyte adhesion deficiency. This was ascribed to a defect of the FERMT3 gene resulting in abnormal expression of kindlin-3, a protein expressed in hematopoietic cells with a major role in the regulation of integrin activation. In this article, we describe a patient with a new mutation of FERMT3 and lack of kindlin-3 expression in platelets and leukocytes. We assayed quantitatively the first steps of kindlin-3-defective leukocyte adhesion, namely, initial bond formation, bond strengthening, and early spreading. Initial bond formation was readily stimulated with neutrophils stimulated by fMLF, and neutrophils and lymphocytes stimulated by a phorbol ester or Mn2+. In contrast, attachment strengthening was defective in the patient's lymphocytes treated with PMA or Mn2+, or fMLF-stimulated neutrophils. However, attachment strengthening was normal in patient's neutrophils treated with phorbol ester or Mn2+. In addition, the patient's T lymphocytes displayed defective integrin-mediated spreading and a moderate but significant decrease of spreading on anti-CD3-coated surfaces. Patient's neutrophils displayed a drastic alteration of integrin-mediated spreading after fMLF or PMA stimulation, whereas signaling-independent Mn2+ allowed significant spreading. In conclusion, the consequences of kindlin-3 deficiency on β2 integrin function depend on both cell type and the stimulus used for integrin activation. Our results suggest looking for a possible kindlin-3 involvement in membrane dynamical event independent of integrin-mediated adhesion. [ABSTRACT FROM AUTHOR]

Ikaros/IKZF1 is an essential transcription factor expressed throughout hematopoiesis. IKZF1 is implicated in lymphocyte and myeloid differentiation and negative regulation of cell proliferation. In humans, somatic mutations in IKZF1 have been linked to the development of B cell acute lymphoblastic leukemia (ALL) in children and adults. Recently, heterozygous germline IKZF1 mutations have been identified in patients with a B cell immune deficiency mimicking common variable immunodeficiency. These mutations demonstrated incomplete penetrance and led to haploinsufficiency. Herein, we report 7 unrelated patients with a novel early-onset combined immunodeficiency associated with de novo germline IKZF1 heterozygous mutations affecting amino acid N159 located in the DNA-binding domain of IKZF1. Different bacterial and viral infections were diagnosed, but Pneumocystis jirovecii pneumonia was reported in all patients. One patient developed a T cell ALL. This immunodeficiency was characterized by innate and adaptive immune defects, including low numbers of B cells, neutrophils, eosinophils, and myeloid dendritic cells, as well as T cell and monocyte dysfunctions. Notably, most T cells exhibited a naive phenotype and were unable to evolve into effector memory cells. Functional studies indicated these mutations act as dominant negative. This defect expands the clinical spectrum of human IKZF1-associated diseases from somatic to germline, from haploinsufficient to dominant negative. [ABSTRACT FROM AUTHOR]

Purpose: A specific biomarker of post-ARDS fibroproliferation could be useful in the identification of patients who could benefit from therapies aiming to modulate fibroproliferation such as corticosteroids.The aim of this prospective study was to determine the best threshold of the N-terminal-peptidetype III procollagen (NT-PCP-III) in non-resolving ARDS to validate this threshold according to the outcome. Methods: Concerning the best threshold of NT-PCP-III, all consecutive patients with a non-resolving ARDS were included if all the following criteria were fulfilled: moderate to severe ARDS lasting for at least 5 days, lung biopsy performed, serum and alveolar NT-PCP-III obtained within 1 week prior to biopsy, and no documented infection contra-indicating the corticosteroids. In the validation cohort part of the study, patients were included at day 7 if they presented a persistent moderate to severe ARDS. Results: Nineteen of 32 patients had fibroproliferatio nonbiopsy. Serum and alveolar NT-PCP-III were higher in patients with fibroproliferation. Using a threshold of 9 µg/L, alveolar NT-PCP-III had the highest accuracy for diagnosing fibroproliferation (sensitivity = 89.5 % and specificity = 92.3 %). Regarding the 51 patients included in the validation cohort, the mortality rate at day 60 was increased in patients presenting an alveolar NT-PCP-III level higher than 9 µg/L (69 vs. 17 %, p < 0.001). The mean alveolar level of NT-PCP-III on day 7 was 8.1-fold higher in nonsurvivors ( p = 0.03). Conclusions: The determination of NT-PCP-III on BAL done at day 7 in persistent ARDS is able to identify patients with fibroproliferation who could be included in a trial of corticosteroids or any other treatment that might help resolve lung fibroproliferation. [ABSTRACT FROM AUTHOR]

The major histocompatibility complex class I related chain (MIC) is a stress-inducible protein modulating the function of immune natural killer (NK) cells, amajor leukocyte subset involved in proper trophoblast invasion and spiral artery remodeling. Aim of the study was to evaluate whether upregulation of soluble MIC (sMIC) may reflect immune disorders associated to vascular pregnancy diseases (VPD). sMIC was more frequently detected in the plasma of women with a diagnostic of VPD (32%) than in normal termmatched pregnancies (1.6%, P < 0.0001), with highest prevalence in intrauterine fetal death (IUDF, 44%) and vascular intrauterine growth restriction (IUGR, 39%). sMIC levels were higher in preeclampsia (PE) than in IUFD (P < 0.01) and vascular IUGR (P < 0.05). sMIC detection was associated with bilateral early diastolic uterine notches (P = 0.037), thrombocytopenia (P = 0.03), and high proteinuria (P = 0.03) in PE and with the vascular etiology of IUGR (P = 0.0038). Incubation of sMIC-positive PE plasma resulted in down regulation of NKG2D expression and NK cell-mediated IFN-γ production in vitro. Our work thus suggests that detection of sMIC molecule in maternal plasma may constitute a hallmark of altered maternal immune functions that contributes to vascular disorders that complicate pregnancy, notably by impairing NK-cell mediated production of IFN-γ, an essential cytokine favoring vascular modeling. [ABSTRACT FROM AUTHOR]

The article discusses the results of a study that evaluated the role of natural killers in the cytomegalovirus reactivation in critically ill patients. The study showed a 27 percent overall occurrence of cytomegalovirus reactivation in the cohort. It concludes that the occurrence of cytomegalovirus reactivation among immunocompetent critically ill patients resulted from impaired natural killer cell function with reduced interferon-gamma secretion.

Rationale: Natural killer cells, as a major source of interferon-γ, contribute to the amplification of the inflammatory response as well as to mortality during severe sepsis in animal models. Objective: We studied the phenotype and functions of circulating NK cells in critically-ill septic patients. Methods: Blood samples were taken ,48 hours after admission from 42 ICU patients with severe sepsis (n = 15) or septic shock (n = 14) (Sepsis group), non-septic SIRS (n = 13) (SIRS group), as well as 21 healthy controls. The immuno-phenotype and functions of NK cells were studied by flow cytometry. Results: The absolute number of peripheral blood CD3-CD56+ NK cells was similarly reduced in all groups of ICU patients, but with a normal percentage of NK cells. When NK cell cytotoxicity was evaluated with degranulation assays (CD107 expression), no difference was observed between Sepsis patients and healthy controls. Under antibody-dependent cell cytotoxicity (ADCC) conditions, SIRS patients exhibited increased CD107 surface expression on NK cells (62.9[61.3-70]%) compared to healthy controls (43.5[32.1-53.1]%) or Sepsis patients (49.2[37.3-62.9]%) (p = 0.002). Compared to healthy (10.2[6.3-13.1]%), reduced interferon-γ production by NK cells (K562 stimulation) was observed in Sepsis group (6.2[2.2- 9.9]%, p<0.01), and especially in patients with septic shock. Conversely, SIRS patients exhibited increased interferon-c production (42.9[30.1-54.7]%) compared to Sepsis patients (18.4[11.7-35.7]%, p<0.01) or healthy controls (26.8[19.3-44.9]%, p = 0.09) in ADCC condition. Conclusions: Extensive monitoring of the NK-cell phenotype and function in critically-ill septic patients revealed early decreased NK-cell function with impaired interferon-γ production. These results may aid future NK-based immunointerventions. [ABSTRACT FROM AUTHOR]

Sterile inflammation resulting from cell death is due to the release of cell contents normally inactive and sequestered within the cell; fragments of cell membranes from dying cells also contribute to sterile inflammation. Endothelial cells undergoing stress-induced apoptosis release membrane microparticles, which become vehicles for proinflammatory signals. Here, we show that stress-activated endothelial cells release two distinct populations of particles: One population consists of membrane microparticles (<1 μm, annexin V positive without DNA and no histones) and another larger (1-3 μm) apoptotic body-like particles containing nuclear fragments and histones, representing apoptotic bodies. Contrary to present concepts, endothelial microparticles do not contain IL-1α and do not induce neutrophilic chemokines in vitro. In contrast, the large apoptotic bodies contain the full-length IL-1α precursor and the processed mature form. In vitro, these apoptotic bodies induce monocyte chemotactic protein-1 and IL-8 chemokine secretion in an IL-1α-dependent but IL-1β-independent fashion. Injection of these apoptotic bodies into the peritoneal cavity of mice induces elevated serum neutrophil-inducing chemokines, which was prevented by cotreatment with the IL-1 receptor antagonist. Consistently, injection of these large apoptotic bodies into the peritoneal cavity induced a neutrophilic infiltration that was prevented by IL-1 blockade. Although apoptosis is ordinarily considered noninflammatory, these data demonstrate that nonphagocytosed endothelial apoptotic bodies are inflammatory, providing a vehicle for IL-1α and, therefore, constitute a unique mechanism for sterile inflammation. [ABSTRACT FROM AUTHOR]

Severe sepsis and septic shock are still deadly conditions urging to develop novel therapies. A better understanding of the complex modifications of the immune systemof septic patients is needed for the development of innovative immunointerventions. Natural killer (NK) cells are characterized as CD3-NKp46+CD56+ cells that can be cytotoxic and/or produce high amounts of cytokines such as IFN-γ. NK cells are also engaged in crosstalks with other immune cells, such as dendritic cells, macrophages, and neutrophils. During the early stage of septic shock, NK cells may play a key role in the promotion of the systemic inflammation, as suggested in mice models. Alternatively, at a later stage, NK cells-acquired dysfunction could favor nosocomial infections and mortality. Standardized biological tools defining patients' NK cell status during the different stages of sepsis are mandatory to guide potential immuno-interventions. Herein, we review the potential role of NK cells during severe sepsis and septic shock. [ABSTRACT FROM AUTHOR]

Background/Aims: To better characterize the molecules involved in leukocyte tissue infiltration during hepatitis C-mixed cryoglobulinemia (HCV-MC)-associated vasculitis. Methods: The involvement of ELAM, ICAM-1 and VCAM-1 was evaluated in 36 patients with HCV-MC vasculitis using three different approaches: concentrations of soluble forms by specific ELISA, tissue expression by immunohistochemistry on patients nerve biopsies, endothelial expression by FACS analysis, on cells activated in vitro by cryoprecipitates purified from HCV-MC patients. Results: Concentrations of sVCAM-1 were significantly elevated in the serum of HCV-MC patients compared to HCV patients without MC, the highest concentrations being found in severe vasculitis. VCAM-1 expression was detected on blood vessels from nerve biopsies performed in patients with severe vasculitis. When added to endothelial cells in vitro, HCV-MC patients cryoprecipitate induced VCAM-1 but also ELAM and ICAM-1 expression possibly through a mechanism due to the C1q complement fraction interaction with endothelial cells, since C1q was consistently present in the cryoprecipitates. Conclusions: VCAM-1 is mainly involved in the pathogenesis of HCV-MC-associated severe vasculitis and may be a potential interesting therapeutic target. [Copyright &y& Elsevier]

The transition from neutrophil to mononuclear-cell infiltrate is a hallmark of acute inflammation. The kinetics of leuko-endothelial adhesion molecule expression and chemokine secretion might participate in the initial recruitment of neutrophils. Neutrophils then die in situ by apoptosis, while mononuclear cells accumulate. We propose that interleukin-6 (IL-6) and its soluble receptor (sIL-6Rα) might regulate the leukocyte recruitment transition, through a shift of chemokine production. This new function of IL-6 might aid in the understanding of its complex role in inflammation: during acute inflammation, IL-6 might favor the resolution of the neutrophilic infiltrate and the initiation of the immune response; in chronic inflammation, IL-6 might increase the mononuclear-cell infiltrate and participate in disease pathogenesis. [Copyright &y& Elsevier]

: Background:The early stage of post-transplant obliterative bronchiolitis (OB) is characterized by an influx of inflammatory cells to the lung, among which neutrophils may play a role in key events. The potential for chemokines to induce leukocyte accumulation in the alveolar space was investigated. We assessed whether changes in the chemotactic expression profile could be used as sensitive markers of the onset of OB.: Methods:Serial bronchoalveolar lavage (BAL) fluids from 13 stable healthy recipients and 8 patients who developed bronchiolitis obliterans syndrome (BOS) were analyzed longitudinally for concentrations of interleukin-8 (IL-8), chemokines regulated-upon-activation and normal T-cell expressed and secreted (RANTES) and monocyte chemoattractant protein-1 (MCP-1), soluble intracellular adhesion molecule-1 (sICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). These were assessed by enzyme-linked immunosorbent assay (ELISA).: Results:Significantly elevated percentages of BAL neutrophils and IL-8 levels were found at the pre-clinical stage of BOS, on average 151 ± 164 days and 307 ± 266 days, respectively, before diagnosis of BOS. There was also early upregulation of RANTES and MCP-1 in the BOS group (mean 253 ± 323 and 152 ± 80 days, respectively, before diagnosis of BOS). The level of MCP-1 was consistently higher than that of RANTES until airway obliteration. BAL sICAM-1 and sVCAM-1 levels were not statistically different between the groups.: Conclusions:These data support the belief that RANTES, IL-8 and MCP-1 play a crucial role in the pathogenesis of OB. The results show that relevant increased levels of such chemokines may predict BOS, and suggest that there is potential for some of these markers to be used as early and sensitive markers of the onset of BOS. Longitudinal monitoring of these chemokine signals may contribute to better management of patients at risk for developing OB, at a stage when remodeling can either be reversed or altered. [Copyright &y& Elsevier]