Inhibitory Factor In Plasma Research Articles

Systemic host inflammation induces stage-specific transcriptomic modification and slower maturation in malaria parasites.

Maturation rates of malaria parasites within red blood cells (RBCs) can be influenced by host nutrient status and circadian rhythm; whether host inflammatory responses can also influence maturation remains less clear. Here, we observed that systemic host inflammation induced in mice by an innate immune stimulus, lipopolysaccharide (LPS), or by ongoing acute Plasmodium infection, slowed the progression of a single cohort of parasites from one generation of RBC to the next. Importantly, plasma from LPS-conditioned or acutely infected mice directly inhibited parasite maturation during in vitro culture, which was not rescued by supplementation, suggesting the emergence of inhibitory factors in plasma. Metabolomic assessments confirmed substantial alterations to the plasma of LPS-conditioned and acutely infected mice, and identified a small number of candidate inhibitory metabolites. Finally, we confirmed rapid parasite responses to systemic host inflammation in vivo using parasite scRNA-seq, noting broad impairment in transcriptional activity and translational capacity specifically in trophozoites but not rings or schizonts. Thus, we provide evidence that systemic host inflammation rapidly triggered transcriptional alterations in circulating blood-stage Plasmodium trophozoites and predict candidate inhibitory metabolites in the plasma that may impair parasite maturation in vivo. IMPORTANCE Malaria parasites cyclically invade, multiply, and burst out of red blood cells. We found that a strong inflammatory response can cause changes to the composition of host plasma, which directly slows down parasite maturation. Thus, our work highlights a new mechanism that limits malaria parasite growth in the bloodstream.

Combination of Plasma MIF and VCA-IgA Improves the Diagnostic Specificity for Patients With Nasopharyngeal Carcinoma.

Introduction:The purpose of this study is to evaluate the diagnostic value of macrophage migration inhibitory factor in patients with nasopharyngeal carcinoma.Materials and Methods:The expression levels of macrophage migration inhibitory factor in nasopharyngeal carcinoma cell lines, tumor tissues, and plasma were measured by real-time polymerase chain reaction, Western blotting, enzyme-linked immunosorbent assay, and immunohistochemistry. Plasma Epstein-Barr virus viral capsid antigen was determined by immunoenzymatic techniques.Results:Both the messenger RNA and protein expression levels of macrophage migration inhibitory factor were upregulated in nasopharyngeal carcinoma cell lines and nasopharyngeal carcinoma tissues. Macrophage migration inhibitory factor in plasma was significantly elevated in patients with nasopharyngeal carcinoma compared to Epstein-Barr virus viral capsid antigen–negative and Epstein-Barr virus viral capsid antigen–positive healthy donors. The combination of macrophage migration inhibitory factor and Epstein-Barr virus viral capsid antigen was better for diagnosing nasopharyngeal carcinoma (area under receiver operating characteristic curve = 0.925, 95% CI: 0.898-0.951) than macrophage migration inhibitory factor (area under receiver operating characteristic curve = 0.778, 95% CI: 0.732-0.824) and Epstein-Barr virus viral capsid antigen. Combining macrophage migration inhibitory factor and Epstein-Barr virus viral capsid antigen had higher specificity (82.40% vs 69.96%) and higher positive predictive value (79.17% vs 67.44%) without an obvious reduction in sensitivity (95.25%) compared to Epstein-Barr virus viral capsid antigen alone. Macrophage migration inhibitory factor was highly expressed in nasopharyngeal carcinoma cell lines, whereas it was not associated with Epstein-Barr virus infection. The level of macrophage migration inhibitory factor in plasma was not related to the titer of Epstein-Barr virus viral capsid antigen.Conclusion:The combination of macrophage migration inhibitory factor and Epstein-Barr virus viral capsid antigen increases the specificity and positive predictive value of detecting nasopharyngeal carcinoma and improves the diagnostic accuracy of nasopharyngeal carcinoma in high-risk individuals.

Influence of medium components on ex vivo megakaryocyte expansion.

Reinfusion of ex vivo-expanded autologous megakaryocytes together with a stem cell transplantation may be useful to prevent or reduce the period of chemotherapy-induced thrombocytopenia. In this study, we analyzed several serum-containing and serum-free media to identify the most suitable medium for megakaryocyte expansion. Moreover, two thrombopoietin (Tpo)-mimetic peptides were tested to evaluate whether they could replace Tpo in an expansion protocol. To analyze the effects of different media on megakaryocyte expansion, we used an in vitro liquid culture system. For this purpose, CD34(+) cells were isolated from peripheral blood and cultured for 8 days in the presence of Tpo and interleukin-3 (IL-3). The presence of megakaryocytes was analyzed by flow cytometric analysis after staining for CD41 expression. For our standard culture procedure, megakaryocyte medium (MK medium) supplemented with 10% AB plasma was used. Addition of 5% or 2.5% AB plasma yielded higher numbers of megakaryocytes, implying the presence of inhibitory factors in plasma. However, some plasma components are required for optimal megakaryocyte expansion because addition of less than 1% AB plasma or addition of human serum albumin instead of AB plasma resulted in the formation of lower numbers of megakaryocytes. Two commercially available serum-free media were also tested: Cellgro and Stemspan. If CD34(+) cells were cultured in Cellgro medium similar numbers of megakaryocytes were obtained as when CD34(+) cells were cultured in MK medium supplemented with 10% AB plasma. In MK medium with 2.5% AB plasma, higher numbers of megakaryocytes were cultured than in MK medium supplemented with 10% AB plasma. Therefore, Cellgro medium is not the best alternative medium. In cultures with Stemspan medium, higher numbers of megakaryocytes were obtained compared to MK medium with 10% AB plasma. Stemspan is thus a good alternative for MK medium. Two Tpo-mimetic peptides, AF13948 and PK1M, were tested for their ability to replace Tpo. In cultures with AF13948, comparable numbers of megakaryocytes were obtained as in the presence of Tpo, but in cultures with PK1M the number of megakaryocytes was lower. This study shows that high concentrations of plasma in medium inhibits megakaryocyte formation, but some plasma components are required for optimal megakaryocyte expansion. For an ex vivo expansion protocol, it is worthwhile to test several media, because the number of megakaryocytes differs widely with the medium used.

Purification and partial characterization of a novel human platelet aggregation factor in the extracellular products of Streptococcus mitis, strain Nm-65

In this paper, we report the purification and partial characterization of human platelet aggregation factor form the extracellular products (ECP) of Streptococcus mitis (S. mitis) isolated from a patient with Kawasaki disease (KD). Platelet aggregation reaction was carried out using platelet-rich plasma (PRP) and washed platelets suspended in ACD-PBS. The aggregation factor was designated as S. mitis-derived human platelet aggregation factor (Sm-hPAF). The results obtained were as follows. 1) Sm-hPAF was isolated by chromatography on DEAE-Sepharose CL-6 B, hydroxyapatite and Superdex 75 columns. The purified Sm-hPAF showed a single band upon SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and molecular weight of approximately 66 kDa on SDS-PAGE. The isoelectric point (pI) of Sm-hPAF was 8.5, and Sm-hPAF showed an absorption peak at 278 nm on absorption spectra. When the platelet aggregation activity of the Sm-hPAF was compared with that of ECP, the specific aggregation activity of the of Sm-hPAF was significantly increased (up to 28-fold). Sugars were not found in Sm-hPAF. The sequence of the first 15 amino-terminal amino acid residues were H.Asp-Glu-Gln-Gly-Asn-Arg-Pro-Val-Glu-Thr-Glu-Asn-Ile-Ala-Arg. The platelet aggregation activity of Sm-hPAF was inactivated by heating at 45 degrees C for 10 min. 2) PGE2 was released from platelets after incubation for 10 min with Sm-hPAF in a dose-dependent fashion. Platelet aggregation by the Sm-hPAF was totally inhibited by either PGE1, or GRGDS, but these reagents did not inhibit the platelet aggregation by collagen. 3) Histological examination of the rabbit skin sites showing an early reaction revealed increased dilatation of the veins and capillaries with cellular infiltration in the perivascular space of the dermis. Hyperplasia of the endothelial cells was noted. Degeneration of the vascular walls was observed in the later stages of the reaction. Aggregation of red cells in the vascular endothelium was also observed. Sm-hPAF was capable of producing vasculitis. 4) Twenty (76.9%) platelet-rich plasma samples (PRP) derived from 26 healthy human volunteers reacted with Sm-hPAF, but the remaining 6 PRPs were not reactive. Preliminary study suggests the existence of an inhibitory factor in plasma from nonreactive donors.

Arenaviral haemorrhagic fevers

Three arenaviruses—Lassa, Junin and Machupo—cause severe haemorrhagic disease in humans: Lassa fever, Argentine haemorrhagic fever and Bolivian haemorrhagic fever, respectively. These conditions are a source of considerable economic hardship in endemic areas and remain a worldwide concern for public-health officials. They are characterised by an insidious onset of influenza-like symptoms followed, in severe cases, by a generalised bleeding diathesis, encephalopathy and death. Central to studies of their pathogenesis is evidence for cellular dysfunction disproportionate to overt histopathology. Recent studies of patients with Lassa fever indicate that platelet and possibly endothelial-cell dysfunction play an important role in the bleeding tendency. The platelet defect appears to be mediated by an inhibitory factor in plasma; the nature of this is uncertain but it seems to be neither viral protein nor virus antibody. A similar inhibitor has since been demonstrated in patients with Argentine haemorrhagic fever. Plasma from patients with Lassa fever also profoundly modulates the amount of superoxide generated by normal neutrophils in response to the chemotactic peptide f-met-leu-phe, suggesting the inhibitor(s) has global effects on cellular function. These findings may have important implications for future therapeutic strategies.

Is chemotactic activity of polymorphonuclear leukocytes increased in psoriasis?

Chemotactic activity of PMNs of 44 patients with common psoriasis and 20 healthy individuals was studied by modified Boyden chamber assay and casein as a chemoattractant. The patients were classified according to the activity of the disease, extent of skin lesions, and duration of the disease and of the last relapse. There was a high statistically significant increase in chemotactic response of the PMNs of psoriatics as compared with controls. The increase in chemotactic activity correlated positively with the activity of the disease but not with the extent of skin lesions. Very low values in some patients with longlasting and/or extensive lesions could depend upon the presence of inhibitory factors in plasma. The possible explanation for divergent results obtained by other authors could be due to the fact that various clinical parameters were not taken into account.

Familial Plasma Lecithin: Cholesterol Acyltransferase Deficiency

A 43-year-old woman and her 47-year-old brother were studied because of corneal opacity. They showed a marked decrease in plasma high density lipoproteins (HDL) and a decrease in the ester ratio of plasma total cholesterol. Discoidal particles were found in the HDL2 fraction (d 1.063-1.125). A marked heterogeneity of low density lipoproteins was disclosed in both patients by electron microscopy. Apoprotein analysis revealed an increase in apo E and a decrease in apo A-I and A-II in both patients. These abnormalities were similar to the data reported in other cases with hereditary lecithin : cholesterol acyltransferase (LCAT) deficiency. However, several interesting dissimilarities have been disclosed as compared with the previously reported cases. Neither patient had proteinuria, and their kidney functions were within the normal limits. The ester ratios of plasma cholesterol of both patients were the highest among the cases reported thus far. Their plasma LCAT activities were 14.4 and 15% of the normal mean values determined by Glomset-Wright's common-substrate method. The enzyme activities determined by Stokke-Norum's self-substrate method were 40.2 and 29% respectively. These results may indicate that this inherited disorder is not characterized by absence of plasma LCAT or presence of inhibitory factors in plasma, but by the presence of partially inactive LCAT in patients' plasma.

1522 EVIDENCE OF CHRONIC RENAL DAMAGE IN PATIENTS WITH STEROID DEPENDENT MINIMAL CHANGE DISEASE (MCD) NEPHROTIC SYNDROME

Renal biopsies of 11 patients with frequently relapsing, steroid-dependent but responsive nephrotic syndrome were evaluated prior to therapy with chlorambucil. There were 7 males and 4 females. Age at onset ranged from 2 to 10 yrs. (mean 4.5) and the duration of disease from 5 mos. to 12 yrs. (mean 3.6 yrs.). Glomerular histology was consistent with MCD and no deposits were seen on immunofluorescence and electron microscopy. However, histological changes of chronic damage were seen in 7/11 patients and included: focal tubular atrophy and thickened tubular basement membrane in 4/11, periglomerular fibrosis 2/11, interstitial fibrosis 4/11, interstitial inflammation 4/11, focal interstitial calcinosis 2/11 and thickened blood vessel wall in 3/11. All patients achieved complete, prolonged remissions with chlorambucil. Three subsequently relapsed but remained steroid responsive. Histological changes of chronicity showed no correlation to age at onset, sex, duration of disease, frequency and/or number of relapses, serum lipid levels, the selectivity of proteinuria and the in-vitro lymphoblast inhibitory factor in plasma. These results show that in some patients with steroid dependent MCD prominent histological evidence of chronic renal damage can occur. Whether these changes induce steroid dependency, are due to prolonged proteinuria, and would progress without therapy to chronic renal failure remains a possibility.

Plasma Thrombopoietic Activity in Humans With Normal and Abnormal Platelet Counts

Although much experimental evidence suggests the presence of a humoral stimulator of thrombopoiesis, relatively few human studies have been done to determine the presence of such a stimulator in disorders of thrombopoiesis. Human plasma fractions from patients with normal and abnormal platelet counts were tested for thrombopoietic stimulatory or inhibitory activity in a mouse bioassay system by measuring the incorporation of 75Se-methionine into platelets of mice injected with plasma fractions. Twenty-two patients with normal platelet counts had no evidence of stimulatory activity in plasma, except for one postoperative patient. Fifty-three percent of 17 patients with thrombocytosis had increased stimulatory activity, and 33% of patients with thrombocytopenia had such activity in plasma. Inhibitory activity in plasma was found in 4 patients with normal platelet counts, 7 with thrombocytopenia, and none with thrombocytosis. A hypothesis based on the presence of both stimulatory and inhibitory factors in plasma is advanced to explain the humoral control mechanisms in normal patients and in patients with abnormal platelet counts of diverse etiology.

Impairment in Platelet Aggregation in Congenital Heart Disease

Abstract Platelet function and coagulation studies were performed on 65 children with congenital heart disease (CHD) and five wtih acquired heart disease, varying in age from 2 wk to 17 yr. Approximately 11% of the children with CHD had mild bleeding symptoms, and 9% had prolonged bleeding times, despite normal platelet counts. In 14 of 37 children (37.8%) with cyanotic CHD and four of 28 (14.3%) with the acyanotic variety, platelet aggregation by adenosine diphosphate (ADP), noradrenalin, and connective tissue suspension was impaired. The possibility of a platelet inhibitory factor in plasma was unlikely. Platelet content of ADP was normal, and high concentrations of exogenous ADP produced an improvement in aggregation, suggesting that the disturbance may be due to defective release of intrinsic ADP from the platelets. Impairment in aggregation was correlated with the severity of hypoxemia and polycythemia in cyanotic patients. Coagulation data did not support the concept that disseminated intravascular coagulation is a frequently associated finding in cyanotic CHD. Our findings reveal a disturbance in platelet function, until now, not commonly associated with CHD.

Leishmania tropica, L. donovani and L. enriettii: Immune rabbit serum inhibitory in vitro

Plasma from rabbits injected with Leishmania tropica showed an inhibitory effect on the growth of Leishmania tropica, enriettii and donovani in vitro. This inhibitory effect was assayed by counting the viable leptomonads under the microscope, using trypan blue as a vital stain. The number of viable leptomonads in cultures containing plasma from injected rabbits decreased steadily, while in cultures of leptomonads with normal rabbit plasma the numbers of leptomonads increased rapidly, reaching a peak on the fifth day of culture. Some effect of the plasma from injected rabbits on the leptomonads could be observed after they were incubated together for 4 hours. The growth inhibitory factor in plasma from injected rabbits is thermostable at 56 °C., its action is independent of the presence of complement, and it could not be adsorbed out by the homologous organism under our experimental conditions. The degree of inhibitory activity of the plasma factor was correlated with the complement fixation titer of the plasma against a soluble antigen of L. tropica.