Guadalupe Rico

Transdermal estradiol in menopausal women depresses interleukin-6 without affecting other markers of immune response

Objective: The aim of this study was to analyze the effect of transdermal estradiol replacement therapy (HRT) on immune function in menopausal women. Study Design: A prospective comparative study was carried out in 30 women, aged 48–55 years, who were divided into two groups; 20 of them received transdermal estradiol 50 µg/day during 3 months and 10 who refused to receive HRT served as controls. Serum interleukins were quantified by specific immunoenzymatic assays; in addition, hormones of somatotropin axis and prolactin (PRL) were quantified by IRMA and RIA. Results: Baseline elevated interleukin (IL)-6 levels decreased significantly (p < 0.001) after transdermal HRT as compared with the nontreated group. Contrarily, IL-2 and IL-10 levels as well as mitogenic induced T-cell proliferation were unchanged under HRT. Insulin-like growth factor-I, growth hormone and PRL levels were unaltered by transdermal HRT. Conclusion: Decrement of IL-6 in parallel with absent effect on some indices of immune activity suggests a beneficial action of transdermal HRT. These findings contrast with those demonstrating an increment of immune response in women taking oral HRT. Thus, the route of administra tion determines the effect of HRT on immune function.

The monocyte locomotion inhibitory factor produced by Entamoeba histolytica inhibits induced nitric oxide production in human leukocytes

Abstract. The monocyte locomotion inhibitory factor, an anti-inflammatory pentapeptide produced by Entamoeba histolytica, inhibits the in vitro production of nitric oxide induced by cytokines (INF-γ, TNF-α) or PMA in human leukocytes. This can be added to the other previously reported functional effects of this factor, such as the inhibition of monocyte locomotion and the synthesis of reactive oxygen intermediates in both monocytes and neutrophils. The decreased nitric oxide production may interfere with the killing of amebas by neutrophils in the early invasive stages of amebiasis, when oxidative mechanisms are used [reactive oxygen and nitrogen intermediates either individually or synergistically via peroxynitrite (ONOO–)], and in the advanced stages, when both non-oxidative and oxidative (including nitric oxide) mechanisms are employed by macrophages. Diminished nitric oxide production by leukocytes may also contribute to the paucity of late inflammatory components in amebic abscess of the liver and other amebic lesions.

A novel anti-inflammatory oligopeptide produced by Entamoeba histolytica

The monocyte locomotion inhibitory factor (MLIF), a heat-stable oligopeptide found in the supernatant fluid of Entamoeba histolytica axenic cultures was isolated by ultra-filtration, gel-sieve chromatography and high powered liquid chromatography (HPLC), and its primary structure (Met-Gln-Cys-Asn-Ser) established by Edman sequencing and mass-spectrometry (MS). A synthetic peptide had the same selective anti-inflammatory features as the native material in comparable concentrations: in vitro inhibition of the locomotion in human peripheral blood monocytes, and of the respiratory burst in the same cells and in human neutrophil polymorphonuclear leucocytes; and in vivo depression of delayed hypersensitivity skin reactions to dinitrochlorobenzene in guinea pigs. This oligopeptide is apparently synthesized by the ameba as suggested by [(35)S]-Cys and Met incorporation, probably as part of a larger molecule, from which it is cleaved by proteolysis. The full sequence was not found in the 431 available E. histolytica protein sequences. The factor may contribute to the unexpected paucity of the late inflammatory reaction found in advanced invasive amebiasis and, perhaps in consequence, to the regeneration without scarring (restitutio ad integrum) of the affected organs that is observed following successful treatment of this disease

An anti‐inflammatory oligopeptide produced by Entamoeba histolytica down‐regulates the expression of pro‐inflammatory chemokines

Axenically grown Entamoeba histolytica produces a pentapeptide (Met‐Gln‐Cys‐Asn‐Ser) with anti‐inflammatory properties that, among others, inhibits the in vitro and in vivo locomotion of human monocytes, sparing polymorphonuclear leucocytes from this effect [hence the name originally given: Monocyte Locomotion Inhibitory Factor (MLIF)]. A synthetic construct of this peptide displays the same effects as the native material. We now added MLIF to resting and PMA‐stimulated cells of a human monocyte cell line and measured the effect upon mRNA and protein expression of pro‐inflammatory chemokines (RANTES, IP‐10, MIP‐1α, MIP‐1β, MCP‐1, IL‐8, I‐309 and lymphotactin) and the shared CC receptor repertoire. The constitutive expression of these chemokines and the CC receptors was unaffected, whereas induced expression of MIP‐1α, MIP‐1β, and I‐309, and that of the CCR1 receptor – all involved in monocyte chemotaxis – was significantly inhibited by MLIF. This suggests that the inhibition of monocyte functions by MLIF may not only be exerted directly on these cells, but also – and perhaps foremost – through a conglomerate down‐regulation of endogenous pro‐inflammatory chemokines.

Effect of the monocyte locomotion inhibitory factor (MLIF) produced by Entamoeba histolytica on the expression of cell adhesion molecules (CAMs) in the skin of guinea pigs.

Entamoeba histolytica synthesizes a heat-stable pentapeptide, originally identified by one of its effects on mononuclear phagocytes (MP) as a monocyte locomotion inhibitory factor (MLIF). In addition to several other in vitro measurable antiinflammatory actions, MLIF was also found in vivo to delay the arrival of the late mononuclear leukocyte component in Rebuck human skin windows (1), and to inhibit the 1-chloro-2-4-dinitrobenzene (DNCB) contact hypersensitivity skin reaction in guinea pigs, a predominantly late mononuclear leukocyte inflammatory animal model (2). To explore whether MLIF also affects the regulation of cell-adhesion molecules (CAMs), we chose to measure the monocyte integrin VLA-4 and its corresponding endothelial ligand, the Ig superfamily VCAM-1, an interaction couple essential for the rolling, adhesion, and eventual extravasation of monocytes (3,4) in the course of a DNCB contact hypersensitivity skin reaction in guinea pigs.

Immunization with a tetramer derivative of an anti‐inflammatory pentapeptide produced by Entamoeba histolytica protects gerbils (Meriones unguiculatus) against experimental amoebic abscess of the liver

Axenically grown Entamoeba histolytica produces a pentapeptide (Met‐Gln‐Cys‐Asn‐Ser) with several anti‐inflammatory properties, including the inhibition of human monocyte locomotion (Monocyte Locomotion Inhibitory Factor (MLIF)). A construct displays the same effects as the native material. It remains to be seen if MLIF is used, or even produced in vivo by the tissue‐invading parasite. If MLIF were to be relevant in invasive amoebiasis, immunizing against it could diminish this parasite advantage and prevent lesions. KLH‐linked MLIF mixed with Freunds adjuvant was too aggressive an immunizing material to answer this question. However, immunization with a tetramer of MLIF (but not a scrambled version of MLIF) around a lysine core (MLIF–MAPS), that displays increased antigenicity, yet lacks excessive innate immunity activation, completely protects gerbils against amoebic abscess of the liver caused by the intraportal injection of virulent E. histolytica. Liver abscesses caused by Listeria monocytogenes were not prevented. Invasive E. histolytica may produce the parent protein of MLIF in vivo, and if appropriately cleaved, it may play a role in invasive amoebiasis. MLIF may join new vaccination strategies against amoebiasis.

Cytokine expression in CD4+ cells exposed to the monocyte locomotion inhibitory factor produced by Entamoeba histolytica

Entamoeba histolytica produces monocyte locomotion inhibitory factor (MLIF), a pentapeptide with in vitro and in vivo anti-inflammatory properties. MLIF may interfere with leukocyte migration, disturbing the balance of pro- and anti-inflammatory cytokines secreted by CD4+ T lymphocytes. We evaluated the effect of MLIF on expression of pro- and anti-inflammatory cytokines in human CD4+ T lymphocytes. Regulatory cytokines [interleukin-1 beta (IL-1β), IL-2, interferon gamma (IFN-γ), IL-5, IL-6, and IL-10] were studied by enzyme-linked immunosorbent assay method in CD4+-cell supernatant fluids. Proinflammatory cytokines were produced per se by MLIF (IL-1β, IL-2, and IFN-γ) and also anti-inflammatory cytokines (IL-5, IL-6, and IL-10) with 1-phorbol-12 myristate-13 acetate + MLIF; the IL-1β, IFN-γ, IL-5 and IL-6 production was inhibited but not that of IL-10 which disclosed increase in its expression. MLIF disturbs the pro- and anti-inflammatory balance, and it induces inhibition of IL-1β (principal proinflammatory cytokine) and increases IL-10 (prototype of an anti-inflammatory cytokine).

The Effect of the Monocyte Locomotion Inhibitory Factor (MLIF) Produced by Entamoeba histolytica upon Nitric Oxide Production by Human Leukocytes

Entamoeba histolytica produces a small molecular weight (583 Da) monocyte locomotion inhibitory factor (MLIF) that without harming the cells, inhibits in vitro and in vivo locomotion of human monocytes/mononuclear phagocytes (MP) but not that of neutrophils (PMNn) or eosinophils. It also virtually cancels the respiratory burst of MP and PMNn, again sparing eosinophils from this effect (1). Nitric oxide (NO) appears to be the principal lytic agent used by rodent MP against E. histolytica in vitro , and human MP may do likewise (2). We evaluated the effect of nMLIF (native) and sMLIF (custom synthetic) on the production of NO by human MP and PMNn after single stimulation, to gain a better understanding of the interaction between E. histolytica and human leukocytes.

Further characterization of a human monocyte locomotion inhibitory factor produced by axenically grownEntamoeba histolytica

The present paper reports on a reevaluation of the thermostability of a partially purified MP locomotion inhibitory factor (MLIF), its preparation from washed and lysed amebas, and its recovery after absorption to MP

Isolation and Structural Studies of the Monocyte Locomotion Inhibitory Factor (MLIF) Produced by Entamoeba histolytica

The supernatant fluid of axenically grown E. histolytica HM-1:IMSS (and virgin axenic medium as control) was obtained by centrifugation and ultrafiltration, and applied to gel-sieve (Sephadex G15) chromatography (1). The 478– 735-Da chromatographic fraction was subjected to reverse phase HPLC-C18. Only the second of five closely emerging peaks revealed MLIF activity (absent from the virgin axenic medium) and was, in turn, subjected to mass-spectrometry: MALDI-MS (2) and tandem MS/MS (TSQ-LC-MS) (3), and Edman sequencing (4). Once the primary chemical structure was known (5), a 96% pure custom MLIF (American Peptide Corp., Sunnyvale, CA, USA) was tested in vitro (human monocyte locomotion in Boyden chambers, as well as monocyte and neutrophil respiratory burst by chemiluminescence) and in vivo (delayed hypersensitivity skin reactions to 1-chloro-2-4 dinitrobenzene in guinea pigs) alongside the native MLIF.