Expression Of Complement Receptors Research Articles

Profiling the expression of complement receptors during the differentiation and polarisation of human monocyte-derived macrophages

Profiling the expression of complement receptors during the differentiation and polarisation of human monocyte-derived macrophages

C1s inhibition by BIVV009 prevents complement-enhanced activation of autoimmune human B cells in vitro

While the mechanisms underlying the functions of the complement system in the central nervous system (CNS) and systemically, namely opsonization, chemotaxis, membrane lysis, and regulation of inflammation are the same, the plethora of functions that complement orchestrates in the central nervous system (CNS) is complex. Strictly controlled expression of complement effector molecules, regulators and receptors across the gamut of life stages (embryogenesis, development and maturation, aging and disease) dictate fascinating contributions for this ancient system. Furthermore, it is becoming apparent that complement functions differ widely across distinct brain regions. This review provides a comprehensive overview of the newly identified roles for complement in the brain, including its roles in CNS development and function, during aging and in the processes of neurodegeneration. The diversity and selectively of beneficial and detrimental activities of complement, while challenging, should lead to precision targeting of specific components to provide disease modifying treatments for devastating psychiatric and neurodegenerative disorders that are still without effective treatment.

New tricks for an ancient system: Physiological and pathological roles of complement in the CNS

While the mechanisms underlying the functions of the complement system in the central nervous system (CNS) and systemically, namely opsonization, chemotaxis, membrane lysis, and regulation of inflammation are the same, the plethora of functions that complement orchestrates in the central nervous system (CNS) is complex. Strictly controlled expression of complement effector molecules, regulators and receptors across the gamut of life stages (embryogenesis, development and maturation, aging and disease) dictate fascinating contributions for this ancient system. Furthermore, it is becoming apparent that complement functions differ widely across distinct brain regions. This review provides a comprehensive overview of the newly identified roles for complement in the brain, including its roles in CNS development and function, during aging and in the processes of neurodegeneration. The diversity and selectively of beneficial and detrimental activities of complement, while challenging, should lead to precision targeting of specific components to provide disease modifying treatments for devastating psychiatric and neurodegenerative disorders that are still without effective treatment.

EXPRESSION OF CELL ADHESION MOLECULES AND COMPLEMENT RECEPTORS IN DIAGNOSTICS OF TRANSPLANTED HEART REJECTION

Aim. Characterization of the changes in expression of cell adhesion molecules and complement receptors in the transplanted heart rejection using computer morphometry to improve the quality of endomyocardial biopsy diagnostics. Materials and methods. Endomyocardial biopsies of 20 patients undergoing cardiac transplantation were used. Histological sections were stained using a standard procedure with hematoxylin and eosin, as well as an indirect immunohistochemical method with the ABC detection system against CD21 and CD31. The area of the positive reaction was estimated with computer morphometry. Results. All biopsies are divided according to the degrees of rejection as follows: degree 0R – 8 samples, 1R – 10 samples, 2R – 7 samples, 3R – 4 samples. CD21 expression is 0.31% in samples with 0R, 1.09% at 1R, 2R rejection of 2.01%, and for 3R – 4.15%. The area occupied by CD31-positive cells is 3.49% in 0R, at 1R rejection this index decreases by 1.3 times, in biopsy samples with 2R this index is 1.8 times less, and for samples with 3R it decreases by 2.6 times. Conclusion. Evaluation of CD21-positive cells in the myocardium allows us to predict cardiosclerosis, as well as a tendency to a chronic clinical course of the rejection. Expression of CD31 makes it possible to assess condition of the microcirculatory vessels in the graft, which is also important for the heart failure prevention.

Maternal Breathing Dysfunction During Pregnancy Alters Microglial Activities and Increases Risk for Psychiatric Disorders in Her Offspring

Each year, over half a million women develop sleep disordered breathing (SDB) by the third trimester, the prevalence of which is increasing in parallel with the obesity epidemic. While negative consequences of SDB during pregnancy on the health of the mother and newborn are becoming better appreciated, nothing is known about the impact of SDB on the neural function of her offspring. SDB is a potent inflammatory stimulus, inducing chronic inflammation that contributes to many of the morbidities associated with SDB. Since epidemiological studies suggest that maternal inflammation is associated with the development of neuropsychiatric disorders in her offspring, we tested the hypothesis that in utero intermittent hypoxia impairs cognitive behavior in the offspring. Pregnant rat dams were exposed to chronic intermittent hypoxia (8 hrs/day, 2 min 10.5% O2 separated by 2 min of 21% O2) or normoxia from gestation days 10–21 (GIH and GNX, respectively). Juvenile (3 week) and adult (8 week) offspring were tested in a Y‐maze spontaneous alternation task, a well‐validated index of spatial working memory. We found that spontaneous alternation performance was severely impaired in juvenile and adult male GIH offspring relative to GNX offspring, suggesting GIH results in early developmental emergence of working memory impairments. In contrast, female GIH offspring did not exhibit impairments in spatial working memory at either age. Microglia isolated from the forebrain of male GIH offspring exhibited significant reductions in the expression of the phagocytic receptor gene complement receptor 3 (CD11b), suggesting that GIH impairs microglial synaptic pruning activities. In the same samples, expression levels of DNA methyltransferase enzymes (DNMTs), that are responsible for repressing gene expression, were increased. Since hypoxia enriches the transcriptional activation mark H3K4me3 in microglial cultures, we hypothesize that GIH upregulates DNMT gene expression via epigenetic histone alterations to fetal microglia, which represses microglial phagocytic gene expression. Together, these data suggest that GIH: 1) sex‐dependently alters cognitive phenotypes in GIH offspring, and 2) may induce epigenetic suppression of microglial phagocytic activities that impair microglial synaptic pruning during development, altering forebrain synaptic connectivity in male offspring.Support or Funding InformationSupported by R01 NS085226 (JJW) and HL105511 (TLB)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Expression of complement receptor 3 (CR3) and regulatory protein CD46 on dendritic cells of antiretroviral naïve and treated HIV-1 infected individuals: Correlation with immune activation status

During infection and budding, human immunodeficiency virus-1 (HIV-1) acquires regulators of Complement Activation (RCAs) along with the host cell membrane on the viral envelope. Activation of host complement system results in opsonization of virus by complement fragments, however the virus evades complement mediated lysis (CoML) by virtue of the RCAs on the viral envelope. The RCAs on HIV-1 envelope process complement protein C3 into various fragments that promote viral entry and infection of cells through different complement receptors. Complement opsonized HIV-1 has been shown in vitro to infect dendritic cells (DCs) in a CR3 dependent manner, although the role of CR3 and CD46 in natural HIV-1 infection is not clear. Surface expression of CR3 and CD46 on DC subsets of 30 antiretroviral naïve, 31 treated (cART) HIV-1 infected individuals and 30 seronegative controls was measured by flow cytometry and plasma levels of cytokines and complement activity (C3c levels) were quantitated by sandwich ELISA. Significantly lower surface expression of CR3 and CD46 was observed on DC subsets in naïve and treated HIV-1 infected individuals compared to controls. Significantly higher complement activation and plasma levels of IL-4, IL-8, IL-10 and IFN-γ were observed in treatment naïve HIV-1 infected individuals than controls. Significantly lower plasma levels of IL-4, IL-6, IL-8 and IL-10 were observed in treated vs. naïve HIV-1 infected individuals. Our findings suggest that alterations in expression of CR3 and CD46 on DCs along with complement activity could be factors that influence viral persistence and HIV-1 disease progression and need to be further evaluated.

Complement system contributes to modulate the infectivity of susceptible TcI strains of Trypanosoma cruzi.

BACKGROUND Trypanosoma cruzi is a protozoan parasite and an etiological agent of Chagas disease. There is a wide variability in the clinical outcome of its infection, ranging from asymptomatic individuals to those with chronic fatal mega syndromes. Both parasite and host factors, as well as their interplay, are thought to be involved in the process.OBJECTIVES To evaluate the resistance to complement-mediated killing in two T. cruzi TcI strains with differential virulence and the subsequent effect on their infectivity in mammalian cells.METHODS Tissue-culture derived trypomastigotes of both strains were incubated in guinea pig serum and subjected to flow cytometry in order to determine their viability and complement activations. Trypomastigotes were also incubated on host cells monolayers in the presence of serum, and infectivity was evaluated under different conditions of complement pathway inhibition. Relative expression of the main parasite-specific complement receptors between the two strains was assessed by quantitative real-time polymerase chain reaction.FINDINGS In this work, we showed that two TcI strains, one with lower virulence (Ninoa) compared to the other (Qro), differ in their resistance to the lytic activity of complement system, hence causing a compromised ability of Ninoa strain to invade mammalian cells. These results correlate with the three-fold lower messenger RNA (mRNA) levels of complement regulatory protein (CRP), trypomastigote-decay acceleration factor (T-DAF), and complement C2 receptor inhibitor trispanning (CRIT) in Ninoa compared to those in Qro. On the other hand, calreticulin (CRT) mRNA and surface protein levels were higher in Ninoa strain and promoted its infectivity when the lectin pathway of the complement system was inhibited.MAIN CONCLUSIONS This work suggests the complex interplay of CRP, T-DAF, CRIT, and CRT, and the diagnostic value of mRNA levels in the assessment of virulence potential of T. cruzi strains, particularly when dealing with isolates with similar genetic background.

Cyclodextrin Reduces Cholesterol Crystal-Induced Inflammation by Modulating Complement Activation.

Cholesterol crystals (CC) are abundant in atherosclerotic plaques and promote inflammatory responses via the complement system and inflammasome activation. Cyclic oligosaccharide 2-hydroxypropyl-β-cyclodextrin (BCD) is a compound that solubilizes lipophilic substances. Recently we have shown that BCD has an anti-inflammatory effect on CC via suppression of the inflammasome and liver X receptor activation. The putative effects of BCD on CC-induced complement activation remain unknown. In this study, we found that BCD bound to CC and reduced deposition of Igs, pattern recognition molecules, and complement factors on CC in human plasma. Furthermore, BCD decreased complement activation as measured by terminal complement complex and lowered the expression of complement receptors on monocytes in whole blood in response to CC exposure. In line with this, BCD also reduced reactive oxygen species formation caused by CC in whole blood. Furthermore, BCD attenuated the CC-induced proinflammatory cytokine responses (e.g., IL-1α, MIP-1α, TNF, IL-6, and IL-8) as well as regulated a range of CC-induced genes in human PBMC. BCD also regulated complement-related genes in human carotid plaques treated ex vivo. Formation of terminal complement complex on other complement-activating structures such as monosodium urate crystals and zymosan was not affected by BCD. These data demonstrate that BCD inhibits CC-induced inflammatory responses, which may be explained by BCD-mediated attenuation of complement activation. Thus, these findings support the potential for using BCD in treatment of atherosclerosis.

Spred2-deficiecy Protects Mice from Polymicrobial Septic Peritonitis by Enhancing Inflammation and Bacterial Clearance

Sepsis is an infection-induced systemic inflammatory syndrome and a major cause of death for critically ill patients. Here, we examined whether the absence of Sprouty-related EVH1-domain-containing protein 2 (Spred2), a negative regulator of the Ras/Raf/ERK/MAPK pathway, influences host defense against polymicrobial sepsis (PMS) induced by cecal ligation and puncture (CLP). Compared to wild-type mice, Spred2−/− mice exhibited higher survival rates with increased level of leukocyte infiltration and local chemokine production and reduced plasma and peritoneal bacterial loads after CLP. The MEK inhibitor U0126 significantly reduced LPS-induced chemokine production by Spred2−/− resident macrophages in vitro, and decreased CLP-induced leukocyte infiltration in vivo. Spred2−/− resident macrophages, but not neutrophils or elicited macrophages, exhibited increased phagocytic activity. Interestingly, surface expression of complement receptor 1/2 (CR1/2) was increased in Spred2−/− resident macrophages in response to lipopolysaccharide in a manner dependent on the ERK/MAPK pathway, and blocking CR1/2 in vivo resulted in reduced leukocyte infiltration and increased bacterial loads after CLP. Taken together, our results indicate that Spred2-deficiency protects mice from PMS via increased activation of the ERK/MAPK pathway and subsequent increase in innate immune responses. Thus, inhibiting Spred2 may present a novel means to prevent the development of PMS.

The Response of Phagocytes to Indoor Air Toxicity.

This perspective presents a viewpoint on potential methods assessing toxicity of indoor air. Until recently, the major techniques to document moldy environment have been microbial isolation using conventional culture techniques for fungi and bacteria as well as in some instances polymerase chain reaction to detect microbial genetic components. However, it has become increasingly evident that bacterial and fungal toxins, their metabolic products, and volatile organic substances emitted from corrupted constructions are the major health risks. Here, we illustrate how phagocytes, especially neutrophils can be used as a toxicological probe. Neutrophils can be used either in vitro as probe cells, directly exposed to the toxic agent studied, or they can act as in vivo indicators of the whole biological system exposed to the agent. There are two convenient methods assessing the responses, one is to measure chemiluminescence emission from activated phagocytes and the other is to measure quantitatively by flow cytometry the expression of complement and immunoglobulin receptors on the phagocyte surface.

Capsular specific IgM enhances complement-mediated phagocytosis and killing of Cryptococcus neoformans by methamphetamine-treated J774.16 macrophage-like cells

Methamphetamine (METH) is a powerful and highly addictive stimulant that affects the central nervous system of users in the United States and worldwide, and its consumption is associated to the acquisition of HIV and AIDS-related infections. METH enhances cryptococcosis in mice, an opportunistic infection caused by the encapsulated fungus Cryptococcus neoformans. Due to its ability to survive within macrophages, C. neoformans is an ideal model to study pathogen-macrophage interactions. METH abrogates normal macrophage function, which might contribute to the higher rate and more rapid progression of infections in drug abusers. Hence, we investigated the role of complement and specific IgM to C. neoformans capsular polysaccharide on the function of J774.16 macrophage-like cells after exposure to METH. We found that complement and IgM significantly promotes complement-mediated phagocytosis of C. neoformans by J774.16 cells in comparison to co-incubation with complement alone. IgM enhances the expression of complement receptor 3 on the surface macrophages treated with the drug. Also, IgM-increased macrophage phagocytosis of C. neoformans may be associated with upregulation of GTPase-RhoA, a key regulator of the actin polymerization signaling cascade. Fungal cells incubated with complement and IgM in the presence of METH demonstrated higher number of cells per aggregate, a possible explanation for their enhanced ingestion by phagocytes. IgM increased killing of yeast cells by macrophages by inhibiting the alkalization of the phagosome and stimulating the intracellular production of nitric oxide. Together, our findings suggest that IgM stimulates the effector functions of macrophages against opportunistic pathogens in the setting of drug abuse.

Low-level arsenic causes chronic inflammation and suppresses expression of phagocytic receptors.

The impact of chronic low-level groundwater arsenic (As) exposure [in the range above the WHO-recommended limit of 10 μg/L but ≤50μg/L (permissible limit of As for many Asian countries)] was investigated for cross talk of inflammatory changes and expression of phagocytic receptors of exposed rural women (N, 45) from districts of 24 Parganas (south) and in matched control groups (N, 43) [As ≤10μg/L] from the same district. Systemic inflammation was evident from the upregulated levels of pro-inflammatory mediators like tumor necrosis factor-α (TNF-α); interleukins (ILs) like IL-6, IL-8, and IL-12; and C-reactive protein (CRP) in the sera and upregulated expression of protein kinase B phosphorylated at ser473 (pAKTser473)/nuclear factor-κB (NF-κB)/TNF-α axis in the leukocytes of exposed women with respect to control. We found that low-dose As exposure apart from inflicting inflammation altered the expression of phagocytic receptors-Fcγ receptors (FcγRs) and complement receptors (CRs). The leukocytes of the low-As-exposed women exhibited suppression of CD64, CD35, and CD11b and increased expression of CD16 with respect to control. Groundwater As showed a negative correlation with CD64 expression on monocytes [Pearson's r, -0.8205; 95% confidence interval (CI), -0.8789 to -0.7379] and granulocytes [r, -0.7635; 95% CI, -0.8388 to -0.6595] and a positive correlation with CD16 on granulocytes [r, 0.8363; 95% CI, 0.7599 to 0.8899]. A negative correlation of groundwater As was also observed with expression of CD35 on granulocytes [r, -0.8780; 95% CI, -0.9185 to -0.8192] and monocytes [r, -0.7778; 95% CI, -0.8490 to -0.6790] and CD11b on monocytes [r, -0.6035; 95% CI, -0.7218 to -0.4511]. Therefore, it may be indicated that chronic low-level As exposure (11-50μg/L) not only evoked chronic inflammatory changes but also suppressed the expression of FcγRs and CRs in the exposed women. This, in turn, may lead to susceptibility towards pathogenic infections or in long run may even contribute towards chronic inflammatory diseases including cancer.

Oral administration of corticosterone at stress-like levels drives microglial but not vascular disturbances post-stroke

Exposure to chronic stress following stroke has been shown, both clinically and pre-clinically, to impact negatively on the recovery process. While this phenomenon is well established, the specific mechanisms involved have remained largely unexplored. One obvious signaling pathway through which chronic stress may impact on the recovery process is via corticosterone, and its effects on microglial activity and vascular remodeling. In the current study, we were interested in examining how orally delivered corticosterone at a stress-like concentration impacted on microglial activity and vascular remodeling after stroke. We identified that corticosterone administration for two weeks following stroke significantly increased tissue loss and decreased the weight of the spleen and thymus. We also identified that corticosterone administration significantly altered the expression of the key microglial complement receptor, CD11b after stroke. Corticosterone administration did not alter the expression of the vessel basement membrane protein, Collagen IV after stroke. Together, these results suggest that corticosterone is likely to represent only one of the major stress signals responsible for driving the negative impacts of chronic stress on recovery.

Alteration in Leukocyte Subsets and Expressions of FcγR and Complement Receptors among Female Ragpickers in Eastern India.

BackgroundThere are a million ragpickers in India who gather and trade recyclable municipal solid wastes materials for a living. The objective of this study was to examine whether their occupation adversely affects their immunity.MethodsSeventy-four women ragpickers (median age, 30 years) and 65 age-matched control housemaids were enrolled. Flow cytometry was used to measure leukocyte subsets, and leukocyte expressions of Fcγ receptor I (CD64), FcγRIII (CD16), complement receptor 1 (CD35) and CR3 (CD11b/CD18), and CD14. Serum total immunoglobulin-E was estimated with enzyme-linked immunosorbent assay.ResultsCompared with the controls, ragpickers had significantly (p < 0.0001) higher levels of CD8+T-cytotoxic, CD16+CD56+natural killer, and CD4+CD45RO+memory T-cells, but depleted levels of CD19+B-cells. The percentage of CD4+T-helper-cells was lower than the control group (p < 0.0001), but their absolute number was relatively unchanged (p = 0.42) due to 11% higher lymphocyte counts in ragpickers. In ragpickers, the percentages of CD14+CD16+intermediate and CD14dim CD16+nonclassical monocyte subsets were elevated with a decline in CD14+CD16-classical monocytes. The expressions of CD64, CD16, CD35, and CD11b/CD18 on both monocytes and neutrophils, and CD14 on monocytes were significantly higher in ragpickers. In addition, ragpickers had 2.7-times more serum immunoglobulin-E than the controls (p < 0.0001). After controlling potential confounders, the profession of ragpicking was positively associated with the changes.ConclusionRagpicking is associated with alterations in both innate (neutrophils, monocytes, and natural killer cell numbers and expression of complement and Fcγ receptors) and adaptive immunity (numbers of circulating B cells, helper, cytotoxic, and memory T cells).

Depletion of complement system immunity in patients with myocardial infarction.

The aim of the present study was to evaluate differences in the expression of complement system genes, and serum levels of CH50, C3 and C4 in peripheral blood mononuclear cells from patients with myocardial infarction (AMI), stable angina pectoris (SA) and controls. A total of 100patients with AMI, 100with SA and 100clinical controls were recruited in the present study. In each group, 20randomly selected individuals were examined using whole human genome microarray analysis to detect the expression of genes of the complement system. The serum levels of CH50, C3 and C4 were measured in all 300subjects. In the patients with AMI, the expression levels of genes encoding C1qα, C1qβ, C1qγ, C1r, Factor P, C5a (complement component), CR1, integrin αM, integrin αX, integrin β2, C5aR, CRIg (complement receptors) and CD46, CD55 and CD59 (complement regulators) were significantly higher, compared with the respective genes in the SA patients and controls (P<0.05), whereas the mRNA levels of C1s, C7, C8β and C9 were the lowest in this group (P<0.05). No statistically significant differences were found in the gene expression levels of complement components or regulators between the SA and control groups. The serum levels of CH50, C3 and C4 were significantly increased in the AMI and SA groups, compared with the controls. In the AMI and SA groups, the complement system was activated. However, the differential mRNA expression of complement components, receptors and regulators in the AMI group suggested the dysfunction of the C5b-9 complex. The depression of complement system immunity in the patients with AMI may be associated with the pathogenesis of AMI.

CRIg-expressing peritoneal macrophages are associated with disease severity in patients with cirrhosis and ascites.

Infections are an important cause of morbidity and mortality in patients with decompensated cirrhosis and ascites. Hypothesizing that innate immune dysfunction contributes to susceptibility to infection, we assessed ascitic fluid macrophage phenotype and function. The expression of complement receptor of the immunoglobulin superfamily (CRIg) and CCR2 defined two phenotypically and functionally distinct peritoneal macrophage subpopulations. The proportion of CRIghi macrophages differed between patients and in the same patient over time, and a high proportion of CRIghi macrophages was associated with reduced disease severity (model for end-stage liver disease) score. As compared with CRIglo macrophages, CRIghi macrophages were highly phagocytic and displayed enhanced antimicrobial effector activity. Transcriptional profiling by RNA sequencing and comparison with human macrophage and murine peritoneal macrophage expression signatures highlighted similarities among CRIghi cells, human macrophages, and mouse F4/80hi resident peritoneal macrophages and among CRIglo macrophages, human monocytes, and mouse F4/80lo monocyte-derived peritoneal macrophages. These data suggest that CRIghi and CRIglo macrophages may represent a tissue-resident population and a monocyte-derived population, respectively. In conclusion, ascites fluid macrophage subset distribution and phagocytic capacity is highly variable among patients with chronic liver disease. Regulating the numbers and/or functions of these macrophage populations could provide therapeutic opportunities in cirrhotic patients.

Platelet bound oxLDL shows an inverse correlation with plasma anaphylatoxin C5a in patients with coronary artery disease

Both oxidized lipids as well as the complement system contribute to atherothrombosis. The expression of complement receptors correlates with the expression of platelet activation markers, and platelet bound oxidized low-density lipoprotein (oxLDL) modulates platelet function. In the present study, we investigated the relationship of markers of complement activation, the anaphylatoxins C5a and C3a, and oxidized low-density lipoprotein.Two hundred and seven patients with coronary artery disease (CAD) were analyzed in this study. Using enzyme-linked immunosorbent assays, plasma levels of oxLDL, C3a, and C5a were measured. Moreover, we assessed platelet bound oxLDL by flow cytometry. The overall level of C5a in the troponin negative group (stable angina (SA) and unstable angina (UA)) compared to the troponin positive group (non-ST-elevation myocardial infarction (NSTEMI) and ST-elevation myocardial infarction (STEMI)) did not differ significantly (62.7 ± 32.4 ng/ml versus 65.8 ± 40.3 ng/ml). While C5a and C3a showed a significant correlation with each other (r = 0.25, p < 0.001), there was no statistically significant relationship between C3a and platelet bound oxLDL (r = 0.06, p = 0.37). Furthermore, plasma oxLDL did not correlate with either C3a or C5a. However, we observed a moderate, yet significant negative correlation between plasma C5a and platelet bound oxLDL (r = −0.15, p = 0.04). Partial correlation analysis correcting for the presence of acute coronary syndrome (ACS), troponin status or the subgroups SA, UA, NSTEMI, or STEMI did not alter this correlation substantially. Interestingly, flow cytometric analysis of human platelets showed increased expression of C5aR and P-selectin after in vitro stimulation with oxLDL.In conclusion, the complement anaphylatoxin C5a shows an inverse correlation with platelet bound oxLDL. The relationship of oxidized lipids to particular complement components may add to the platelet–lipid interplay in atherogenesis and trigger future clinical and mechanistic studies.

Control of Methicillin-Resistant Staphylococcus aureus Pneumonia Utilizing TLR2 Agonist Pam3CSK4.

The spread of methicillin-resistant Staphylococcus aureus (MRSA) is a critical health issue that has drawn greater attention to the potential use of immunotherapy. Toll-like receptor 2 (TLR2), a pattern recognition receptor, is an essential component in host innate defense system against S. aureus infection. However, little is known about the innate immune response, specifically TLR2 activation, against MRSA infection. Here, we evaluate the protective effect and the mechanism of MRSA murine pneumonia after pretreatment with Pam3CSK4, a TLR2 agonist. We found that the MRSA-pneumonia mouse model, pretreated with Pam3CSK4, had reduced bacteria and mortality in comparison to control mice. As well, lower protein and mRNA levels of TNF-α, IL-1β and IL-6 were observed in lungs and bronchus of the Pam3CSK4 pretreatment group. Conversely, expression of anti-inflammatory cytokine IL-10, but not TGF-β, increased in Pam3CSK4-pretreated mice. Our additional studies showed that CXCL-2 and CXCL1, which are necessary for neutrophil recruitment, were less evident in the Pam3CSK4-pretreated group compared to control group, whereas the expression of Fcγ receptors (FcγⅠ/Ⅲ) and complement receptors (CR1/3) increased in murine lungs. Furthermore, we found that increased survival and improved bacterial clearance were not a result of higher levels of neutrophil infiltration, but rather a result of enhanced phagocytosis and bactericidal activity of neutrophils in vitro and in vivo as well as increased robust oxidative activity and release of lactoferrin. Our cumulative findings suggest that Pam3CSK4 could be a novel immunotherapeutic candidate against MRSA pneumonia.

Phagocytosis in Mesocestoides vogae-induced peritoneal monocytes/macrophages via opsonin-dependent or independent pathways

Summary Intraperitoneal infection with larvae of cestode Mesocestoides vogae offers the opportunity to study dynamic changes in the proportion and functions of individual cell types under a direct influence of parasites. The phagocytic activity is one of the basic effector functions of professional phagocytes and receptor-mediated uptake is a central in implementation of inflammatory responses. Present study extends information on this issue by exploring several phagocytosis pathways in M. vogae-induced myelo-monocytic cells. In addition, we analyzed proportions of morphologically distinct phenotypes within macrophage compartments after oral inoculation of larvae to mice. In gradually elevated population of peritoneal exudate cells, monocytes/ macrophages and giant cell were dominant cell types from day 21 p.i. Phagocytic activity of these cells had biphasic behaviour for both opsonin-dependent and independent pathways, whereas uptake by multinucleated macrophages was profoundly reduced. Highly elevated proportions of activated phagocytic cells were found from day 7 to 14 p.i., regardless particle type (latex beads, HEMA, liposomes) and opsonisation. Source of opsonins used for coating of liposomes suggested higher expression of complement receptors than Fc receptors on these cells, although the uptake of non-opsonized liposomes had different kinetics and was very high by activated cells early p.i. Present data indicate that early recruited macrophages/monocytes attain pro-inflammatory functions as indicated by highly elevated phagocytosis of immunologically inert particles as well as opsonized liposomes what is down-regulated once larvae start to proliferate in the peritoneal cavity, suggesting the role of parasite-derived molecules in modulation of this key phagocytes function.

Depression of Complement Regulatory Factors in Rat and Human Renal Grafts Is Associated with the Progress of Acute T-Cell Mediated Rejection.

BackgroundThe association of complement with the progression of acute T cell mediated rejection (ATCMR) is not well understood. We investigated the production of complement components and the expression of complement regulatory proteins (Cregs) in acute T-cell mediated rejection using rat and human renal allografts.MethodsWe prepared rat allograft and syngeneic graft models of renal transplantation. The expression of Complement components and Cregs was assessed in the rat grafts using quantitative real-time PCR (qRT-PCR) and immunofluorescent staining. We also administered anti-Crry and anti-CD59 antibodies to the rat allograft model. Further, we assessed the relationship between the expression of membrane cofactor protein (MCP) by immunohistochemical staining in human renal grafts and their clinical course.ResultsqRT-PCR results showed that the expression of Cregs, CD59 and rodent-specific complement regulator complement receptor 1-related gene/protein-y (Crry), was diminished in the rat allograft model especially on day 5 after transplantation in comparison with the syngeneic model. In contrast, the expression of complement components and receptors: C3, C3a receptor, C5a receptor, Factor B, C9, C1q, was increased, but not the expression of C4 and C5, indicating a possible activation of the alternative pathway. When anti-Crry and anti-CD59 mAbs were administered to the allograft, the survival period for each group was shortened. In the human ATCMR cases, the group with higher MCP expression in the grafts showed improved serum creatinine levels after the ATCMR treatment as well as a better 5-year graft survival rate.ConclusionsWe conclude that the expression of Cregs in allografts is connected with ATCMR. Our results suggest that controlling complement activation in renal grafts can be a new strategy for the treatment of ATCMR.