Three novel homozygous ITGB2 mutations among two patients with leukocyte adhesion defect type-1:Two case reports

BACKGROUND A leukocyte adhesion defect(LAD) is a rare primary immunodeficiency disorder. LAD type 1(LAD-1) is the most common, which is caused by ITGB2 mutation resulting in dysfunction of β2 integrin, which impairs leukocyte adherence to the endothelium.CASE SUMMARY The first two cases of LAD-1 in Thailand presented with recurrent omphalitis, soft tissue infection, marked leukocytosis, and neutrophilia. One patient experienced delayed umbilical cord separation. Mutation analysis was performed by direct DNA sequencing of the ITGB2 gene. The results revealed two novel homozygous missense mutations, c.920C>T(p.Leu307Pro) in exon 8 and c.758G>A(p.Arg-253His) in exon 7, and one novel homozygous nonsense mutation, c.262C>T(p.Gln88Ter) in exon 4, in the genomic DNA of the first and second patients, respectively. Heterozygous mutations were identified in the parents of both patients, suggesting a carrier status. The patients were administered intravenous antibiotics for infections with good clinical responses. Hematopoietic stem cell transplantation could not be performed due to the unavailability of matched donors. However, a significant decline in infections was observed after antibiotic prophylaxis. Several follow-up visits were conducted for both patients. They are currently 6 years old.CONCLUSION Molecular analysis is essential for definitive diagnosis, early treatment implementation, and prevention of LAD-1 in future pregnancy.

A novel point mutation in CD18 causing leukocyte adhesion deficiency in a Chinese patient

Background Leukocyte adhesion deficiency type 1 （LAD-l） is a rare, autosomal recessive inherited immunodeficiency disease characterized by recurrent severe bacterial infection, impaired pus formation, poor wound healing, associated with the mutation in the CD18 gene responsible for the ability of the leucocytes to migrate from the blood stream towards the site of inflammation. Correct and early diagnosis of LAD-1 is vital to the success of treatment and prevention of aggressive infections. The purpose of this study was to collect the clinical findings of the disease and to identify the genetic entity. Methods CD18 expression in the peripheral blood leukocytes from the patient, his parents and normal control was measured with flow cytometry. The entire coding regions of the CD18 gene were screened with direct sequencing genomic DNA. Results CD18 expression level on this patient＇s leukocyte surface was significantly decreased, with normal level in control group, his father and mother. Gene analysis revealed that this patient had a homozygous c.899A〉T missense mutation in exon 8 of CD18 gene, causing the substitution of Asp to Val at the 300 amino acid. His parents were both heterozygous carriers while no such mutation was found in 50 normal controls. Conclusion This study disclosed a novel point mutation Asp 300 Val located in a highly conserved region （HCR） of CD18 and confirmed the heterogeneity of the mutations causing LAD-1, indicating it was quite beneficial to establish correct and early diagnosis in children with severe LAD-1.

Expression of leukocyte adhesion molecules CD11b, L-selectin and CD45 during hemodialysis

ObjectiveTo examine the gene and protein expression of CD11b, L selectin and CD45, and the relationship between their expression and leukocytopenia during a hemodialysis session Methods Ten maintenance hemodialysis patients, 20 uremic non dialysis patients and 10 healthy volunteers were included in this study The mRNA expression of CD11b, L selectin and CD45 in peripheral blood mononuclear cells was detected by RT PCR, while cell surface expression of these molecules on monocytes was detected by flow cytometry and leukocyte number was counted manually Results After the start of dialysis, both mRNA expression and cell surface expression of CD11b increased rapidly, while those of L selectin and leukocyte number fell The mRNA expression of CD45 first decreased and the cell surface expression increased, followed by a return to pre dialysis levels, by the end of dialysis Conclusions Hemodialysis using a cuprophane membrane can induce rapid upregulation of CD11b and down regulation of L selectin, which might influence the normal adhesion and anti inflammatory response of leukocytes In this process CD45 may play a role in regulating and/or transducing activation signal

Effect of Antioxidants on Endothelial Cell Reactive Oxygen Species (ROD Generation and Adhesion of Leukocytes to Endothelial Cells

Objective To investigatewhether antioxidants inhibit adhesion of leukocytes to endothelium and furthermore, whether all antioxidants regulate NF-KB activation through a redox sensitive mechanism. Methods The effect of the antioxidative substances pyrrolidin dithiocarbamat (PDTC), dichloroisocumarin (DCI), chrysin and probucol on the endothelial leukocyte adhesion were examined under near physiological flow conditions. The antioxidative activity of antioxidants was measured in a DCF fluorescence assay with flow cytometry. The activation of NF-kB in endothelial cells was investigated in a gel shift assay. Results PDTC and probucol did not show an inhibitory effect to the formation of intracellular H2O2 in TNFa activated human vascular endothelial cells (HUVEC) . Chrysin showed a moderate effect. DCI showed a strong antioxidative effect. In contrast, PDTC and chrysin inhibited the adhesion of HL 60 cells to TNFa-stimulated HUVEC. DCI and probucol did not have influence on the adhesion within the area of the examined shear stresses. Only PDTC inhibited the TNFa-induced activation of NF-KB in endothelial cells. Conclusion The inhibition of the endothelial leukocyte adhesion by antioxidative substances is not to be explained by its antioxidative characteristics only. The inhibitory effect of PDTC on NF-KB activation was probably not related to its antioxidative properties. Endothelial cell Antioxidants NF-kappa-B

P-selectin glycoprotein ligand 1 deficiency prevents development of acute pancreatitis by attenuating leukocyte infiltration

BACKGROUND Acute pancreatitis(AP) is rapid-onset pancreatic inflammation that causes local and systemic inflammatory response syndrome(SIRS) with high morbidity and mortality, but no approved therapies are currently available. P-selectin glycoprotein ligand 1(PSGL-1) is a transmembrane glycoprotein to initiate inflammatory responses. We hypothesized that PSGL-1 may be involved in the development of AP and would be a new target for the treatment of AP.AIM To investigate the role and mechanism of PSGL-1 in the development of AP.METHODS The PSGL-1 expression on leukocytes was detected in peripheral blood of AP patients and volunteers. Pancreatic injury, inflammatory cytokines expression, and inflammatory cell infiltration was measured in AP mouse models induced with PSGL-1 knockout(PSGL-1-/-) and wild-type(PSGL-1+/+) mice. Leukocyteendothelial cell adhesion was measured in a peripheral blood mononuclear cell(PBMC)-endothelial cell coculture system.RESULTS The expression of PSGL-1 on monocytes and neutrophils was significantly increased in AP patients. Compared with PSGL-1+/+ mice, PSGL-1-/-AP mice induced by caerulein exhibited lower serum amylase, less Interleukin-1 beta(IL-1 beta) and Interleukin-6(IL-6) expression, less neutrophil and macrophage infiltration, and reduced peripheral neutrophil and monocyte accounts. PSGL-1 deficiency alleviated leukocyte-endothelial cell adhesion via IL-6 but not IL-1 beta.CONCLUSION PSGL-1 deficiency effectively inhibits the development of AP by preventing leukocyte-endothelial cell adhesion via IL-6 stimulation and may become a potential therapeutic target for treating AP.

In vivo observation of cerebral microcirculation after experimental subarachnoid hemorrhage in mice

Acute brain injury caused by subarachnoid hemorrhage is the major cause of poor prognosis. The pathology of subarachnoid hemorrhage likely involves major morphological changes in the microcirculation. However, previous studies primarily used fixed tissue or delayed injury models. Therefore, in the present study, we used in vivo imaging to observe the dynamic changes in cerebral microcirculation after subarachnoid hemorrhage. Subarachnoid hemorrhage was induced by perforation of the bifurcation of the middle cerebral and anterior cerebral arteries in male C57/BL6 mice. The diameter of pial arterioles and venules was measured by in vivo fluorescence microscopy at different time points within 180 minutes after subarachnoid hemorrhage. Cerebral blood flow was examined and leukocyte adhesion/albumin extravasation was determined at different time points before and after subarachnoid hemorrhage. Cerebral pial microcirculation was abnormal and cerebral blood flow was reduced after subarachnoid hemorrhage. Acute vasoconstriction occurred predominantly in the arterioles instead of the venules. A progressive increase in the number of adherent leukocytes in venules and substantial albumin extravasation were observed between 10 and 180 minutes after subarachnoid hemorrhage. These results show that major changes in microcirculation occur in the early stage of subarachnoid hemorrhage. Our findings may promote the development of novel therapeutic strategies for the early treatment of subarachnoid hemorrhage.

Influence of Traditional Chinese Medicine Qingjieling on LFA-1-Dependent Leukocyte Adhesion to Endothelial Cells

Objective: To investigate the influence of traditional Chinese medicine Qingjieling on leukocyte adhesion to vascular endothelial cells and the possible mechanisms. Methods: Firstly, We successfully established in vitro culture of human umbilical vein endothelial cells (HUVEC) monolayer. Then we constructed a leukocyte-endothelial cell adhesion model and imitated the inflammation state by using endothelial cells stimulated with recombinant tumor necrosis factor a (TNFa) or interleukin-1 (IL-1 ) respectively. The drug-induced change of leukocyte adhesion function was observed after we directly administered traditional Chinese medicine Qingjieling on the leukocytes. Finally, we inquired into the molecular mechanism of the effect of Qingjieling by monoclonal antibody blocking assay. Results: HUVEC as a representative large vessel endothelial cell could perfectly construct an adhesion model with leukocytes. Under the stimulation of cytokines (TNFa or IL-1), endothelial cells demonstrated drastically improved adhesion with leukocytes, certain dose of Qingjieling (ling/g body weight) might augment the leukocyte adhesion capacity with a 2-hour co-incubation. At least part of the reason of Qingjieling's improving adhesion effect is due to the increased lymphocyte functional associated antigen-1 (LFA-1) expression of the white blood cells. Conclusion: Qingjieling could increase LFA-1-dependent leukocytes adhesion to endothelial cells.

A non-human primate derived anti-P-selectin glycoprotein ligand-1 antibody curtails acute pancreatitis by alleviating the inflammatory responses

Acute pancreatitis(AP)is a devastating disease characterized by an inflammatory disorder of the pancreas.P-selectin glycoprotein ligand-1(PSGL-1)plays a crucial role in the initial steps of the adhesive at process to inflammatory sites,blockade of PSGL-1 might confer potent anti-inflammatory effects.In this study,we generated two non-human primate derived monoclonal antibodies capable of efficiently targeting human PSGL-1,RH001-6 and RH001-22,which were screened from immunized rhesus macaques.We found that RH001-6,can effectively block the binding of P-selectin to PSGL-1,and abolish the adhesion of leukocytes to endothelial cells in vitro.In vivo,we verified that RH001-6 relieved inflammatory responses and pancreatic injury in both caerulein and L-arginine induced AP models.We also evaluated the safety profile after RH001-6 treatment in mice,and verified that RH001-6 did not cause any significant pathological damages in vivo.Taken together,we developed a novel non-human primate derived PSGL-1 blocking antibody with high-specificity,named RH001-6,which can interrupt the binding of PSGL-1 and P-selectin and attenuate inflammatory responses during AP.Therefore,RH001-6 is highly potential to be further developed into therapeutics against acute inflammatory diseases,such as AP.

Ameliorating effects of traditional Chinese medicine preparation, Chinese materia medica and active compounds on ischemia/reperfusion-induced cerebral microcirculatory disturbances and neuron damage

Ischemic stroke and ischemia/reperfusion(I/R) injury induced by thrombolytic therapy are conditions with high mortality and serious long-term physical and cognitive disabilities. They have a major impact on global public health. These disorders are associated with multiple insults to the cerebral microcirculation, including reactive oxygen species(ROS) overproduction, leukocyte adhesion and infiltration, brain blood barrier(BBB) disruption, and capillary hypoperfusion, ultimately resulting in tissue edema, hemorrhage, brain injury and delayed neuron damage. Traditional Chinese medicine(TCM)has been used in China, Korea, Japan and other Asian countries for treatment of a wide range of diseases.In China, the usage of compound TCM preparation to treat cerebrovascular diseases dates back to the Han Dynasty. Even thousands of years earlier, the medical formulary recorded many classical prescriptions for treating cerebral I/R-related diseases. This review summarizes current information and underlying mechanisms regarding the ameliorating effects of compound TCM preparation, Chinese materia medica,and active components on I/R-induced cerebral microcirculatory disturbances, brain injury and neuron damage.

Paeonol Improves Lipopolysaccharide-induced Microcirculatory Disturbance in Rat Mesentery

Objective: To investigate the effect of paeonol on lipopolysaccheride(LPS)-induced rat mesenteric microcirculatory dysfunctions.Methods: Male Wistar rats were randomly distributed into 5 groups(n=6 in each): Sham group, LPS group, paeonol group, paeonol+LPS group, and LPS+paeonol group. Endotoximia model was conducted by continuous LPS infusion. Changes in mesenteric microcirculatory variables, including diameter of venule, velocity of red blood cells in venule, leukocyte adhesion, free radicals produced in venule and albumin leakage from venule, were observed through an inverted intravital microscope. Meanwhile, the expression of myeloperoxidase(MPO), CD18,intercellular adhesion molecule-1(ICAM-1), toll-like receptor 4(TLR4), nuclear factor-kappa B p65 subunit(NF-κB p65), activator protein-1(AP-1), and Jun N-terminal kinase(JNK) was assessed by Western blot.Results: After infusion of LPS, the number of leukocytes adherent to venular wall, the intensity of dihydrorhodamine 123(DHR)fluorescence in the venular walls, and albumin leakage from venules were significantly increased, whereas the red blood cell velocity in venule was decreased. All the manifestations were significantly reduced by pre-treatment and post-treatment with paeonol. Moreover, paeonol significantly attenuated the expression of MPO, CD18, ICAM-1, TLR4, NF-κB p65, AP-1 and JNK in rat mesentery after LPS.Conclusions: The results demonstrated that paeonol could protect from and ameliorate the microcirculation disturbance induced by LPS.

E-selectin ligand complexes adopt an extended high-affinity conformation

E-selectin is a cell-adhesion molecule of the vascular endothelium that promotes essential leukocyte rolling in the early inflammatory response by binding to glycoproteins containing the tetrasaccharide sialyl Lewisx(sLex).Efficient leukocyte recruitment under vascular flow conditions depends on an increased lifetime of E-selectin/ligand complexes under tensile force in a so-called catch-bond binding mode.Co-crystal structures of a representative fragment of the extracellular E-selectin region with sLex and a glycomimetic antagonist thereof reveal an extended E-selectin conformation,which is identified as a high-affinity binding state of E-selectin by molecular dynamics simulations.Small-angle X-ray scattering experiments demonstrate a direct link between ligand binding and E-selectin conformational transition under static conditions in solution.This permits tracing a series of concerted structural changes connecting ligand binding to conformational stretching as the structural basis of E-selectin catch-bond-mediated leukocyte recruitment.The detailed molecular view of the binding site paves the way for the design of a new generation of selectin antagonists.This is of special interest,since their therapeutic potentialwas recently demonstrated with the pan-selectin antagonists GMI-1070(Rivipansel).

Panax Notoginseng Saponins Restrains Ischemia-reperfusion-induced Rat Mesenteric Microcirculatory Disturbance

Objective: To investigate the effect of Panax notoginseng saponins(PNS) on ischemia reperfusion(I/R) induced rat mesenteric microcirculatory dysfunctions.Methods: Male Wistar rats weighting 200–250 g were subjected to 10 min ligation of the superior mesenteric artery and vein, followed by60 min reperfusion. PNS(5 mg/kg/hr) was continuously administrated starting from 10 min before ischemia or 10 min after reperfusion until60 min after reperfusion via left jugular vein. Leukocytes adhesion, mast cell degranulation, endothelial peroxidation, and albumin leakage of rat mesenteric venules were observed. Serum myeloperoxidase(MPO) level, intercellular adhesion molecule-1(ICAM-1) expression and Src phosphorylation were examined.Results: PNS ameliorated leukocyte adhesion and mast cell degranulation, while with no obvious effects on endothelial peroxidation and albumin leakage. In addition, PNS inhibited serum MPO increase, intestinal ICAM-1 expression and Src phosphorylation induced by I/R.Conclusions: PNS ameliorated I/R-induced leukocyte adhesion and mast cell degranulation, the former is related to its inhibition of Src phosphorylation and ICAM-1 expression.