Phagocytic Ability Of Peritoneal Macrophages Research Articles

Elevated heme impairs macrophage phagocytosis in endometriosis.

Endometriosis (EMS) is a chronic inflammatory disease characterized by the presence of extrauterine endometrial tissues. It has been previously reported that the refluxed blood containing viable endometrial tissues and the defective elimination of peritoneal macrophages in the pelvic cavity may involve in EMS pathogenesis. However, the mechanism by which macrophages exhibit attenuated phagocytic capability in EMS remains undetermined. Herein, we found that heme, the byproduct of lysed erythrocytes, accumulated abnormally in the peritoneal fluid (PF) of patients with EMS (14.22 μmol/L, 95% confidence interval (CI): 12.54-16.71), compared with the EMS-free group (9.517 μmol/L, 95% CI: 8.891-10.1053). This abnormal accumulation was not associated with the color of PF, phase of the menstrual cycle or severity of the disease. The reduced phagocytic ability of peritoneal macrophages (pMφs) was observed in the EMS group. Consistently, a high-concentration (30 μmol/L) heme treatment impaired EMS-pMφs phagocytosis more than a low-concentration (10 μmol/L) heme treatment. A similar phenomenon was observed in the EMS-free control pMφs (Ctrl-pMφs) and the CD14+ peripheral monocytes (CD14+ Mos). These results indicated that a high heme concentration exhibits a negative effect on macrophage phagocytosis, which supplements the mechanism of impaired scavenger function of pMφs in EMS.

Eutopic endometrium from patients with endometriosis modulates the expression of CD36 and SIRP-α in peritoneal macrophages.

AimThis study aimed to investigate the in vitro alterations of the expression of signal regulatory protein‐α (SIRP‐α) and CD36 in macrophages in the endometriosis condition.MethodsThe expression of SIRP‐α and CD36 was measured in peritoneal macrophages and peripheral blood mononuclear cells of endometriosis patients and control participants. The expressions of SIRP‐α and CD36 were measured in human acute monocytic leukemia (THP‐1) cell‐derived macrophages that were treated with interleukin‐6 (IL‐6)‐induced conditioned medium, eutopic versus normal endometrial homogenate, or lipopolysaccharide in the presence or absence of nuclear factor kappa‐B (NF‐κB) or transforming growth factor (TGF‐β) inhibitors, respectively.ResultsPeritoneal macrophages that were isolated from women with endometriosis exhibited an enhanced expression of SIRP‐α and a decreased expression of CD36 compared to control participants. Women with endometriosis had significantly higher levels of SIRP‐α and CD36 in peripheral circulating mononuclear cells than in control participants. SIRP‐α expression was significantly increased, whereas the CD36 expression was decreased in THP‐1 cell‐derived macrophages after treatment with eutopic endometrial homogenate. Intervention with IL‐6‐induced conditioned medium resulted in the downregulation of SIRP‐α but the upregulation of CD36 in THP‐1 cells. Incubation with the NF‐κBp50 inhibitor decreased the expression of CD36 and SIRP‐α in macrophages that were treated with normal endometrial homogenate, whereas the TGF‐β inhibitor enhanced the CD36 expression of THP‐1 cell‐derived macrophages treated with eutopic endometrial homogenate.ConclusionThe eutopic endometrium could reduce the phagocytic ability of peritoneal macrophages in women with endometriosis through the modulation of SIRP‐α and CD36 expression. Inhibition of the TGF‐β signal pathway may be a potential therapeutic target for the treatment of endometriosis.

Suppression of annexin A2 by prostaglandin E2 impairs phagocytic ability of peritoneal macrophages in women with endometriosis

Is annexin A2 involved in the reduced phagocytic ability of macrophages in endometriosis? Data from women with endometriosis and a murine model of the disease show that expression of annexin A2 in peritoneal macrophages is inhibited by prostaglandin E2 (PGE2) and this impairs the phagocytic ability of macrophages. Endometriosis is a chronic inflammatory disease that recruits many immune cells, especially macrophages, to the peritoneal cavity. The phagocytic ability of peritoneal macrophages isolated from women with endometriosis is reduced. A laboratory study. Thirty-five patients (20 with and 15 without endometriosis) of reproductive age with normal menstrual cycles were recruited. Peritoneal macrophages isolated from women with or without endometriosis were cultured and treated with vehicle, PGE2 and different EP receptor agonists, and the expression of annexin A2 was quantified by RT-PCR and western blotting. Annexin A2 was knocked down (by small interfering RNA) in normal macrophages or overexpressed (by treatment with recombinant protein) in endometriotic macrophages and their phagocytic ability was measured by flow cytometry. Peritoneal macrophages were isolated from a mouse model of endometriosis and treated with PGE2 or cyclo-oxygenase (COX) inhibitors, and annexin A2 mRNA was quantified. Levels of annexin A2 were markedly reduced in peritoneal macrophages from women with endometriosis versus controls (mRNA: P < 0.01). The level of annexin A2 mRNA in the macrophages was reduced by PGE2 (P < 0.01/P < 0.05 in women without/with endometriosis versus control) via the EP2/EP4 receptor-dependent signaling pathway. Treatment with PGE2 or knockdown of annexin A2 inhibited the phagocytic ability of macrophages (P < 0.05 versus control), while treatment with annexin A2 recombinant protein enhanced phagocytosis. Autologous transplantation animal studies further confirmed that levels of annexin A2 in peritoneal macrophages were markedly reduced in mice treated with PGE2 (P < 0.01 versus control). In contrast, treatment with COX inhibitors to inhibit PGE2 production enhanced annexin A2 expression in peritoneal macrophages (P < 0.05 versus control). We have provided no direct demonstration that phagocytic activity is indeed decreased in peritoneal cells from patients with endometriosis or that their endometriotic fluid contains increased amounts of PGE2 when compared with control subjects. Inhibiting PGE2 signaling, in order to restore or enhance the phagocytic capability of macrophages, may represent a new direction of thinking in developing novel strategies against endometriosis. This work was supported by grants from National Science Council of Taiwan, Republic of China (NSC97-2314-B-006-020-MY3) to M.-H.W. and (NSC98-2320-B-006-026-MY3) to S.-J.T., and grants from the Chang Gung Memorial Hospital, Taiwan, Republic of China (CMRPG891432 and CMRPG8A0531) to P.-C.C. None of the authors have any conflicts of interest.

Immunostimulatory and anti-neoplasm effects of a novel palindrome CpG oligodeoxynucleotide in mice

DNAs containing unmethylated CpG motifs can stimulate innate and adaptive immunity. The aim of this study was to investigate the immunostimulatory and anti-neoplasm effects of a novel CpG oligodeoxynucleotide, ODN10, in tumor-bearing mice. B16 melanoma-bearing C57BL/6 mice were administered ip or sc with ODN10 or conventional CpG ODN1826 on the indicated days post inoculation. The animal survival rate and the inhibitory effect on tumor growth were observed in vivo. B and T lymphocyte proliferation, natural killing cell cytotoxicity and the phagocytic ability of peritoneal macrophages from the animals were determined using [(3)H]-thymidine incorporation assay, 4-h (51)Cr release assay and neutral red chromometry method, respectively. The serum levels of IL-12, IL-4 and IgE were quantified using ELISA assays. Histological examination of tumor tissues was performed after HE staining, and the expression of PCNA, CD63, and CD80 in tumor tissues was analyzed with immunohistochemistry. ODN10 (1, 5 and 25 mg/kg) significantly inhibited the growth and metastasis of the tumor, and significantly prolonged the survival of tumor-bearing mice, as compared with ODN1826. The immune status was suppressed in tumor-bearing mice. Both ODN10 and ODN1826 significantly reversed the suppressed immunoactivities in tumor-bearing mice, which included promoting B and T lymphocyte proliferation, enhancing NK cell and peritoneal macrophage activities, inducing IL-12 secretion and inhibiting IL-4 and IgE secretion. Further, CpG ODNs decreased PCNA and CD63 expression while induced expression of CD80. ODN10 presented more potent activity, and displayed the most prominent immunostimulatory potential. ODN10 produces prominent immunomodulatory effects on cellular immunity in tumor-bearing mice, which might help reverse the established Th2-type responses to the Th1-type responses, thus may be used as a potent anti-tumor immunotherapy agent or adjuvant.

Inhibition of CD36-Dependent Phagocytosis by Prostaglandin E 2 Contributes to the Development of Endometriosis

Dysfunction in macrophage-mediated phagocytosis of aberrant cells that undergo retrograde transport to the peritoneal cavity is considered an important factor in the development of endometriosis. However, the mechanisms responsible for the loss of function of macrophages remain largely unknown. Herein, we report that prostaglandin (PG) E(2), via the EP2 receptor-dependent signaling pathway, inhibits the expression of CD36 in peritoneal macrophages, resulting in reduced phagocytic ability. PGE(2)-mediated inhibition of macrophage phagocytic capability was restored by ectopic expression of CD36. Treatment with PGE(2) inhibited CD36-dependent phagocytosis of peritoneal macrophages and increased the number and size of endometriotic lesions in mice. In contrast, blockade of PGE(2) production by cyclooxygenase inhibitors enhanced the phagocytic ability of peritoneal macrophages and reduced endometriotic lesion formation. Taken together, our findings reveal a potential mechanism of immune dysfunction during endometriosis development and may contribute to the design of an effective prevention/treatment regimen.

Downregulation of CD36 results in reduced phagocytic ability of peritoneal macrophages of women with endometriosis

Endometriosis, defined as the growth of endometrial tissues outside of the uterine cavity, is a severe and complex disease affecting more than 10% of women. The aetiology of endometriosis is unclear but immune dysfunction might be an important factor for its development. The natural function of the immune system is to detect and destroy aberrant or abnormal cells. Failure of the immune system to eradicate these aberrant cells often results in disease pathogenesis. We report here that the phagocytic ability of macrophages is reduced in peritoneal macrophages isolated from women with endometriosis. In-depth investigation revealed that the level of CD36, a class B scavenger receptor, in peritoneal macrophages derived from women with endometriosis was lower than that in normal macrophages. Blockage of CD36 function by neutralized antibody or knocking down CD36 using siRNA impaired the phagocytic ability of normal macrophages. In contrast, forced expression of CD36 in macrophages isolated from women with endometriosis restored phagocytic ability. Taken together, we identified that the scavenger receptor CD36 is reduced in the peritoneal macrophages of women with endometriosis, which leads to a decrease of the phagocytic ability of macrophages. These findings revealed a potential mechanism of immune dysfunction during endometriosis development.

Cancer Protective Action of Polysaccharide, Derived from Red Microalga Porphyridium Cruentum—A Biological Background

ABSTRACTThe cell wall sulfated polysaccharide of the red microalga Porphyridium cruentum (Rhodophyta) (PcrPSH) exhibited strong antitumor activity against Graffi myeloid tumor in hamsters both in vitro and in vivo. When tested in vivo, depending on the concentration and the way of application, this polysaccharide decreased transplantability in all experimental groups till 20 days of observation and mortality rate. The tumor growth was retarded and the mean survival time was prolonged with 10 - 16 days. Applied in in vitro experiments the PcrPSH increased both—spreading and phagocytic ability of peritoneal macrophages from healthy and Graffi tumor bearing hamsters in a dose—dependent manner. Primary Graffi tumor cell culture, cultivated in the presence of PcrPSH showed significant decrease of cell viability, determined by MTT test, while in cells derived from bone marrow it was increased at the same conditions of cultivation and concentration of polysaccharide. Primary Graffi tumor cell culture, treated with PcrPSH showed the appearance of a characteristic DNA ladder on agarose gel electrophoresis, which is a biochemical hallmark of apoptosis. The manifested anticancer activity of PcrPSH could be associated with its immunostimulating action as well as with direct cytotoxic properties. Based on these results, we could suggest that the tested algal PcrPSH is a promising candidate as an antitumor agent. Further studies will be done to clarify the mechanisms of a biological action of PcrPSH.

Decreased expression of scavenger receptor CD36 in peritoneal macrophage of women with endometriosis

OBJECTIVE: Under physiological conditions, scavenger receptors serve to scavenge or clean up cellular debris and other related materials, and they play a role in host defense. Considering the functional role of scavenger receptors in mediating phagocytosis, it is reasonable to hypothesize that the levels of scavenger receptors in peritoneal macrophages may play an important role in the pathogenesis of endometriosis.DESIGN: A prospective, experimental study.MATERIALS AND METHODS: To determine which factors are responsible for reduced phagocytosis, peritoneal macrophages were isolated from patients with or without endometriosis and the expression of several scavenger receptors was examined by RT-PCR. We further analyzed the expression in peritoneal macrophages isolated from control group, and women with early- and severe-stage endometriosis by real time RT-PCR, when the difference was significant.RESULTS: Preliminary data revealed that CD36, SR-AI, SR-AII, SR-BI, and SR-BII were expressed by peritoneal macrophages while SR-AIII was undetectable. By comparing the expression level of these scavenger receptors in normal and endometriosis peritoneal macrophages, level of CD 36 in macrophages isolated from endometriosis was lower than that from normal macrophage while levels of the other scavenger receptors mRNAs were not different. The results of real time RT-PCR further demonstrated that expression of CD36 in peritoneal macrophages isolated from women with endometriosis was less than that from normal women. Concordantly, the phagocytic ability of peritoneal macrophages isolated from women with endometriosis was weaker than those isolated from healthy women.CONCLUSIONS: The result clearly provides strong evidence to support our hypothesis that CD36 plays important role in phagocytosis and the pathological process of endometriosis. Further studies are warranted to investigate detail mechanisms of regulation of CD36 expression in peritoneal macrophages and its clinical implications in the development of endometriosis. OBJECTIVE: Under physiological conditions, scavenger receptors serve to scavenge or clean up cellular debris and other related materials, and they play a role in host defense. Considering the functional role of scavenger receptors in mediating phagocytosis, it is reasonable to hypothesize that the levels of scavenger receptors in peritoneal macrophages may play an important role in the pathogenesis of endometriosis. DESIGN: A prospective, experimental study. MATERIALS AND METHODS: To determine which factors are responsible for reduced phagocytosis, peritoneal macrophages were isolated from patients with or without endometriosis and the expression of several scavenger receptors was examined by RT-PCR. We further analyzed the expression in peritoneal macrophages isolated from control group, and women with early- and severe-stage endometriosis by real time RT-PCR, when the difference was significant. RESULTS: Preliminary data revealed that CD36, SR-AI, SR-AII, SR-BI, and SR-BII were expressed by peritoneal macrophages while SR-AIII was undetectable. By comparing the expression level of these scavenger receptors in normal and endometriosis peritoneal macrophages, level of CD 36 in macrophages isolated from endometriosis was lower than that from normal macrophage while levels of the other scavenger receptors mRNAs were not different. The results of real time RT-PCR further demonstrated that expression of CD36 in peritoneal macrophages isolated from women with endometriosis was less than that from normal women. Concordantly, the phagocytic ability of peritoneal macrophages isolated from women with endometriosis was weaker than those isolated from healthy women. CONCLUSIONS: The result clearly provides strong evidence to support our hypothesis that CD36 plays important role in phagocytosis and the pathological process of endometriosis. Further studies are warranted to investigate detail mechanisms of regulation of CD36 expression in peritoneal macrophages and its clinical implications in the development of endometriosis.

Immunoprotective Properties of Peptidoglycan Monomer Linked with Zinc in Cholestatic Jaundice

Background: Previously it was shown that a new immunostimulator, peptidoglycan monomer linked with zinc (PGM-Zn), might have immunocorrective and hepatotropic effects. Owing to this in the present study we investigated its effects on jaundice-induced immunodysfunction, which might be responsible for serious peri- and postoperative complications in biliary obstruction. Methods: In vivo effects of PGM-Zn were analyzed in mice subjected to common bile duct ligation (CBDL), where we estimated phenotypic profile and cell cycle of thymocytes, splenocytes and phagocytic function of peritoneal macrophages. In vitro effects of PGM-Zn were evaluated on blastogenesis of human peripheral blood mononuclear cells (PBMNC), obtained from healthy donors and stimulated with anti-CD3 monoclonal antibody and/or PMA, in the presence or absence of jaundice serum obtained from patients with biliary calculosis. Results and Discussion: Jaundice induced marked disarrangement of lymphatic homeostasis, which at several points might be blocked by PGM-Zn. In mice it delayed the CBDL-induced decline of CD4+ CD8+ thymocytes, decreased the proportion of CD8+ T cells, and increased the percentage of CD4– CD8– thymocytes, augmenting simultaneously the proportion of thymic cells in S and G2 + M phase of cycle. Similar hyperplastic reaction with increased percentage of CD4+, Ig+ and CD5+ cells was noticed in the spleen, together with the enhanced phagocytic ability of peritoneal macrophages. In human PBMNC jaundice reduced the percentages of CD3, CD5, CD4, CD8 and HLA-DR-expressing cells and increased the proportion of CD25 and perforin-positive lymphocytes. PGM-Zn given in vitro was able to abrogate the antiproliferative activity of jaundice serum on PMA and anti-CD3 + PMA-induced blastogenesis.

Superoxide production by phagocytes in myeloid Graffi tumor-bearing hamsters.

A progressive suppression of the phagocytic ability of peritoneal macrophages and polymorphonuclears (PMNs) in hamsters with transplanted myeloid tumors was previously established. The i.p. application of Cu/Zn SOD, isolated from the fungal strain Humicola lutea (HLSOD) (2 injections before and 5 injections after tumor transplantation) induced the mean survival time of the animals as well as a temporally stimulating action on the macrophage and PMNs phagocyting indices. In the present work, the superoxide production of peritoneal macrophages and PMNs during 30 days of tumor progression was followed. Effects of the application of HLSOD in an optimal protective dose on the superoxide production in peritoneal macrophages and blood PMNs were examined. The spontaneous and phorbol-myristate acetate (PMA)-inducible O2- production in both types of phagocytes was 4-5-fold increased in tumor-bearing hamsters (TBH), as compared to the controls, at day 14 after tumor transplantation (the day of tumor appearance in transplanted animals). Furthermore, O2- production was also similar to the control values for the following days of observation. HLSOD treatment of TBH induced a normalization of superoxide production in macrophages and PMNs. Therefore, the established decrease of superoxide anions in phagocyting cells of TBH indicates possible effects of HLSOD on the host antioxidant defense.

Effect of mercury on the immune response and mean intensity ofAscaris suuminfection in guinea pigs

The subchronic effect of mercury on selected immunological parameters was studied in guinea pigs with experimental Ascaris suum infection. HgC1(2) given for 28 days reduced significantly T- and B-cell populations in the lymphoid organs and the phagocytic ability of peritoneal macrophages. The subsequent infection of HgC1(2)-intoxicated animals elevated the studied immunological parameters, but in comparison with infected non-intoxicated guinea pigs they remained significantly suppressed. The mercury compound in infection stressed animals caused a slight alteration of the complement CH50 and AH50 activity. The specific circulating antibody level in infected and HgC1(2) treated animals rose a little by day 12 p.i. and then again decreased significantly, compared with untreated guinea pigs. The mean intensity of infection with migrating Ascaris larvae in HgC1(2)-treated animals increased by 15%, compared with controls.

The effect of sublethal endrin exposure on rainbow trout, Salmo gairdneri Richardson. I. Evaluation of serum cortisol concentrations and immune responsiveness

Two‐hundred‐and‐forty rainbow trout, Salmo gairdneri, were exposed for 30 days to sublethal concentrations of the pesticide endrin. On day 30, ten fish from each treatment group were sacrificed and examined for the ability of peritoneal macrophages to phagocytize latex beads. The remaining fish were immunized with 10 μg of Yersinia ruckeri O‐antigen, and exposure to endrin continued. The migration inhibition factor assay (MIF), plaque forming cell assay (PFC), and serum agglutination titres (SAG) were performed 2, 14, and 30 days post‐antigen inoculation. Serum was collected from all fish for serum cortisol concentrations. Endrin exposure had no effect on the phagocytic ability of peritoneal macrophages. However, the MIF, PFC and SAG responses were significantly reduced from control values. Serum cortisol concentrations were found to be significantly elevated in endrin‐exposed fish. Serum cortisol concentrations were found to be significantly higher on days 44 and 60 (192 and 194 ng ml−1, respectively) when compared to days 30 and 32 (159 and 141 ng ml−1, respectively). Cortisol values for days 30 and 32 did not differ significantly, nor did those of days 44 and 60. The relationship between elevated serum cortisol concentrations and endrin exposure on the immune response is discussed.

Effect of Diet on the Immune Response of Rainbow Trout (Salmo gairdneri)

To compare the effect of diet on the immune response of rainbow trout (Salmo gairdneri), we maintained fish on either a commercial feed or a laboratory prepared (control) diet for 12–16 wk before antigenic exposure. The immune response to two antigens, sheep red blood cells (SRBC) and Yersinia ruckeri, was assessed. Both T-cell (migration inhibition factor) and B-cell (plaque-forming cell) responses to SRBC were measured. The plaque-forming cell response and the humoral (serum antibody) responses to Y. ruckeri were assayed. In addition, the phagocytic ability of peritoneal macrophages was assessed as a nonspecific resistance factor. We found that fish maintained on the commercial diet had a significantly lower immune response when compared with fish fed the control diet, although all fish appeared healthy and suffered no mortalities throughout the experiment. We indicate the importance of considering the effects of diet on immunity and disease resistance in future feed formulations.