The mode of action of aspirin-like drugs: effect on inducible nitric oxide synthase.

Nitric oxide synthesized by inducible nitric oxide synthase (iNOS) has been implicated as a mediator of inflammation in rheumatic and autoimmune diseases. We report that exposure of lipopolysaccharide-stimulated murine macrophages to therapeutic concentrations of aspirin (IC50 = 3 mM) and hydrocortisone (IC50 = 5 microM) inhibited the expression of iNOS and production of nitrite. In contrast, sodium salicylate (1-3 mM), indomethacin (5-20 microM), and acetaminophen (60-120 microM) had no significant effect on the production of nitrite at pharmacological concentrations. At suprapharmacological concentrations, sodium salicylate (IC50 = 20 mM) significantly inhibited nitrite production. Immunoblot analysis of iNOS expression in the presence of aspirin showed inhibition of iNOS expression (IC50 = 3 mM). Sodium salicylate variably inhibited iNOS expression (0-35%), whereas indomethacin had no effect. Furthermore, there was no significant effect of these nonsteroidal anti-inflammatory drugs on iNOS mRNA expression at pharmacological concentrations. The effect of aspirin was not due to inhibition of cyclooxygenase 2 because both aspirin and indomethacin inhibited prostaglandin E2 synthesis by > 75%. Aspirin and N-acetylimidazole (an effective acetylating agent), but not sodium salicylate or indomethacin, also directly interfered with the catalytic activity of iNOS in cell-free extracts. These studies indicate that the inhibition of iNOS expression and function represents another mechanism of action for aspirin, if not for all aspirin-like drugs. The effects are exerted at the level of translational/posttranslational modification and directly on the catalytic activity of iNOS.

Evidence of autocrine modulation of macrophage nitric oxide synthase by alpha-melanocyte-stimulating hormone.

alpha-Melanocyte-stimulating hormone (alpha-MSH) is a potent inhibitory agent in all major forms of inflammation. To identify a potential mechanism of antiinflammatory action of alpha-MSH, we tested its effects on production of nitric oxide (NO), believed to be a mediator common to all forms of inflammation. We measured NO and alpha-MSH production in RAW 264.7 cultured murine macrophages stimulated with bacterial lipopolysaccharide and interferon gamma. alpha-MSH inhibited production of NO, as estimated from nitrite production and nitration of endogenous macrophage proteins. This occurred through inhibition of production of NO synthase II protein; steady-state NO synthase II mRNA abundance was also reduced. alpha-MSH increased cAMP accumulation in RAW cells, characteristic of alpha-MSH receptors in other cell types. RAW cells also expressed mRNA for the primary alpha-MSH receptor (melanocortin 1). mRNA for proopiomelanocortin, the precursor molecular of alpha-MSH, was expressed in RAW cells, and tumor necrosis factor alpha increased production and release of alpha-MSH. These results suggest that the proinflammatory cytokine tumor necrosis factor alpha can induce macrophages to increase production of alpha-MSH, which then becomes available to act upon melanocortin receptors on the same cells. Such stimulation of melanocortin receptors could modulate inflammation by inhibiting the production of NO. The results suggest that alpha-MSH is an autocrine factor in macrophages which modulates inflammation by counteracting the effects of proinflammatory cytokines.

Inflammatory mediators increase surface expression of integrin ligands, adhesion to lymphocytes, and secretion of interleukin 6 in mouse Sertoli cells.

The expression of the cell adhesion molecules ICAM-1, ICAM-2, and VCAM-1 and the secretion of the cytokine interleukin 6 have been measured in mouse Sertoli cells cultured in vitro. Cytometric analysis revealed that, in basal conditions, low levels of ICAM-1 and VCAM-1 were present on the surface of the cells, whereas treatment with interleukin 1, tumor necrosis factor alpha, lipopolysaccharide, or interferon gamma induced, with different kinetics, increases in their expression. ICAM-2 was not detectable in basal conditions, nor was it inducible. Electron microscopic analysis and binding experiments using 51Cr-labeled lymphocytes demonstrated that increased expression of ICAM-1 and VCAM-1 on the surface of Sertoli cells, induced by inflammatory mediators, determines an augmented adhesion between the two cell types. The same stimuli, with the exception of interferon gamma, produced a rapid and remarkable increment of interleukin 6 production by Sertoli cells. These results suggest the presence of both direct and paracrine mechanisms of interaction between Sertoli and immune-competent cells, possibly involved in the control of immune reactions in the testis. Such mechanisms are of interest for the understanding of autoimmune pathologies of the testis and, if confirmed in humans, they could be involved in the sexual transmission of human immunodeficiency virus infection.

Inflammation-induced recombinant protein expression in vivo using promoters from acute-phase protein genes.

We report that promoters for two murine acute-phase protein (APP) genes, complement factor 3 (C3) and serum amyloid A3 (SAA3), can increase recombinant protein expression in response to inflammatory stimuli in vivo. To deliver APP promoter-luciferase reporter gene constructs to the liver, where most endogenous APP synthesis occurs, we introduced them into a nonreplicating adenovirus vector and injected the purified viruses intravenously into mice. When compared with the low levels of basal luciferase expression observed prior to inflammatory challenge, markedly increased expression from the C3 promoter was detected in liver in response to both lipopolysaccharide (LPS) and turpentine, and lower-level inducible expression was also found in lung. In contrast, expression from the SAA3 promoter was found only in liver and was much more responsive to LPS than to turpentine. After LPS challenge, hepatic luciferase expression increased rapidly and in proportion to the LPS dose. Use of cytokine-inducible promoters in gene transfer vectors may make it possible to produce antiinflammatory proteins in vivo in direct relationship to the intensity and duration of an individual's inflammatory response. By providing endogenously controlled production of recombinant antiinflammatory proteins, this approach might limit the severity of the inflammatory response without interfering with the beneficial components of host defense and immunity.

Molecular cloning and characterization of a cDNA encoding monoclonal nonspecific suppressor factor.

The monoclonal nonspecific suppressor factor (MNSF) is a lymphokine product of a murine T-cell hybridoma that inhibits the generation of lipopolysaccharide-induced immunoglobulin-secreting cells in an antigen-nonspecific manner. A cDNA clone encoding MNSF beta (an isoform of MNSF) was isolated and expressed in bacteria. The sequence obtained is virtually identical to the Fau protein, a product of the ubiquitously expressed fau gene with unknown function. Northern blot analysis demonstrated a single, 0.6-kb transcript. Specific polyclonal antibodies against synthetic peptides corresponding to the deduced amino acid sequences were elicited in rabbits. Immunoprecipitation experiments with these antibodies showed that MNSF beta is released extracellularly in an aggregate form, albeit it lacks a signal peptide sequence. The anti-MNSF beta affinity eluate from the MNSF-producing murine hybridoma (E17) and concanavalin A-activated splenocyte culture supernatants inhibited the immunoglobulin production by lipopolysaccharide-activated splenocytes. Recombinant MNSF beta also showed a similar biologic activity. Thus, ubiquitin-like protein(s) may be involved in the regulation of the immune responses.

Lipocortin 1 mediates the inhibition by dexamethasone of the induction by endotoxin of nitric oxide synthase in the rat.

Administration of Escherichia coli lipopolysaccharide (LPS; 10 mg/kg i.v.) to male Wistar rats caused within 240 min (i) a sustained fall (approximately 30 mmHg) in mean arterial blood pressure, (ii) a reduction (> 75%) in the pressor responses to norepinephrine (1 microgram/kg i.v.), and (iii) an induction of nitric oxide synthase (iNOS) as measured in the lung. Dexamethasone (1 mg/kg i.p. at 2 h prior to LPS) attenuated the hypotension and the vascular hyporeactivity to norepinephrine and reduced (by approximately 77%) the expression of iNOS in the lung. These effects of dexamethasone were prevented by pretreatment of LPS-treated rats with a neutralizing antiserum to lipocortin 1 (anti-LC1; 60 mg/kg s.c. at 24 h prior to LPS) but not by a control nonimmune sheep serum. Stimulation of J774.2 macrophages with LPS (1 microgram/ml for 24 h) caused the expression of iNOS and cyclooxygenase 2 (COX-2) protein and significantly increased nitrite generation; this was prevented by dexamethasone (0.1 microM at 1 h prior to LPS), which also increased cell surface lipocortin 1. Pretreatment of J774.2 cells with anti-LC1 (1:60 dilution at 4 h prior to LPS) also abolished the inhibitory effect of dexamethasone on iNOS expression and nitrite accumulation but not that on COX-2 expression. A lipocortin 1 fragment (residues 1-188 of human lipocortin 1; 20 micrograms/ml at 1 h prior to LPS) also blocked iNOS in J774.2 macrophages activated by LPS (approximately 78% inhibition), and this too was prevented by anti-LC1. We conclude that the extracellular release of endogenous lipocortin 1 (i) mediates the inhibition by dexamethasone of the expression of iNOS, but not of COX-2, and (ii) contributes substantially to the beneficial actions of dexamethasone in rats with endotoxic shock.

Induction of the gene encoding mucosal vascular addressin cell adhesion molecule 1 by tumor necrosis factor alpha is mediated by NF-kappa B proteins.

Mucosal vascular addressin cell adhesion molecule 1 (MAdCAM-1) is involved in trafficking of lymphocytes to mucosal endothelium. Expression of MAdCAM-1 is induced in the murine endothelial cell line bEnd.3 by tumor necrosis factor alpha (TNF-alpha), interleukin 1, and bacterial lipopolysaccharide. Here we show that TNF-alpha enhances expression of a firefly luciferase reporter directed by the MAdCAM-1 promoter, confirming transcriptional regulation of MAdCAM-1. Mutational analysis of the promoter indicates that a DNA fragment extending from nt -132 to nt +6 of the gene is sufficient for TNF-alpha inducibility. Two regulatory sites critical for TNF-alpha induction were identified in this region. DNA-binding experiments demonstrate that NF-kappa B proteins from nuclear extracts of TNF-alpha-stimulated bEnd.3 cells bind to these sites, and transfection assays with promoter mutants of the MAdCAM-1 gene indicate that occupancy of both sites is essential for promoter function. The predominant NF-kappa B binding activity detected with these nuclear extracts is a p65 homodimer. These findings establish that, as with other endothelial cell adhesion molecules, transcriptional induction of MAdCAM-1 by TNF-alpha requires activated NF-kappa B proteins.

Differential modulation of Th1- and Th2-related cytokine mRNA expression by a synthetic peptide homologous to a conserved domain within retroviral envelope protein.

The influence of a synthetic retroviral peptide, CKS-17, on T helper type 1 (Th1)- or Th2-related cytokines was investigated in human blood mononuclear cells. Cells were stimulated with staphylococcal enterotoxin A, anti-CD3 plus anti-CD28 monoclonal antibodies, or lipopolysaccharide to induce cytokine mRNA. mRNA was detected by a reverse transcription-polymerase chain reaction or Northern blot analysis. CKS-17 down-regulated stimulant-induced mRNA accumulation for interferon gamma (IFN-gamma), interleukin (IL)-2, and p40 heavy and p35 light chains of IL-12, a cytokine that mediates development of Th1 response. CKS-17 up-regulated stimulant-induced mRNA accumulation of IL-10 and did not suppress Th2-related cytokine (IL-4, IL-5, IL-6, or IL-13) mRNA expression. A reverse sequence of CKS-17 peptide, used as a control, showed no such action. Anti-human IL-10 monoclonal antibody blocked ability of CKS-17 to inhibit mRNA accumulation for IFN-gamma but not the CKS-17 suppressive activity of IL-12 p40 heavy chain mRNA. Thus, CKS-17-mediated suppression of IFN-gamma mRNA expression is dependent upon augmentation of IL-10 production by CKS-17. This conserved component of several retroviral envelope proteins, CKS-17, may act as an immunomodulatory epitope responsible for cytokine dysregulation that leads to suppression of cellular immunity.

Influência do LPS e do zinco na interação mãe e filhote

O comportamento materno consiste em um conjunto de mudanças comportamentais e fisiológicas, exercidas pelos indivíduos adultos em torno dos indivíduos reprodutivamente imaturos, garantindo sua sobrevivência e a propagação de sua espécie. A interação mãe e filhote é tida tipicamente como simbiótica. Os filhotes quando separados da mãe sinalizam para serem recolhidos através de dicas olfativas, visuais e da vocalização que representa uma forma de comunicação filhote e mãe. O modelo de febre clássico e amplamente empregado envolve a utilização do lipopolissacarídeo (LPS), principal componente da parede celular de bactérias Gram-Negativas. Além da febre, as infecções apresentam uma cadeia de respostas não especificas do hospedeiro que se sabe estarem envolvidos em muitas das funções vitais, incluindo a resposta imune estas incluem a hipozinquemia. Sendo assim, fêmeas virgens, gestantes e lactantes receberam LPS (100 µg/kg, i.p.) e foram tratadas com zinco (2 mg/kg, s.c.) O peso corporal, consumo de água, ração, e a temperatura corporal foram medidas por noventa e seis horas, duas horas após a administração do LPS. No quinto dia de lactação foram observados o comportamento maternal, a atividade geral em campo aberto e a vocalização ultrassônica nos filhotes. No dia do desmame os filhotes dessas fêmeas receberam um desafio com LPS (50 µg/kg, i.p.) e duas horas após a administração, foram observados a atividade geral em campo aberto, e o burst e fagocitose de neutrófilos. Observamos que: 1) Em ratas virgens, gestantes e lactantes, a exposição ao LPS e o tratamento com zinco modificou de forma específica a temperatura e peso corporal, consumo de água e ração e a atividade geral observadas em campo aberto; 2) No período de lactação, houve redução da latência para busca do primeiro filhote. Na prole das fêmeas lactantes verificou-se que: 3) Houve alteração no padrão de vocalização dos filhotes; 4) houve alteração na atividade geral observada em campo aberto e no burst e fagocitose de neutrófilos no vigésimo primeiro dia pós natal, após um desafio com a endotoxina, Assim, os resultados indicam que a administração de LPS e o tratamento com zinco têm seus efeitos modulados conforme o estágio fisiológico em que a fêmea se encontra, e interfere com a interação mãe/filhote, resultando em efeitos de curto e longo prazo sobre o comportamento dos filhotes. A partir deste trabalho, a possibilidade da exposição de mães à endotoxina bacteriana e da modulação de seus efeitos pelo zinco programar as respostas inflamatórias dos filhos torna-se factível

Efeito das gorduras interesterificadas sobre o desenvolvimento da lesão aterosclerótica em camundongos knockout para o receptor de LDL

Nas últimas décadas, diversos estudos têm demonstrado os efeitos nocivos dos ácidos graxos trans à saúde. Consequentemente, diversas agências reguladoras de saúde e sociedades responsáveis pela elaboração de diretrizes nutricionais recomendaram a redução do consumo desses ácidos graxos. Deste modo, a indústria de alimentos vem adequando seus produtos a fim de substituir os ácidos graxos trans por gorduras interesterificadas, porém seus efeitos sobre o desenvolvimento da aterosclerose não foram ainda totalmente elucidados. Portanto, o objetivo deste estudo foi avaliar o efeito de gorduras interesterificadas contendo principalmente ácido graxo palmítico ou esteárico sobre o desenvolvimento da aterosclerose. Desta forma, camundongos knockout para o receptor de LDL (LDLr-KO) recém-desmamados foram alimentados por 16 semanas com dietas hiperlipídicas (40% do valor calórico total sob forma de gordura) contendo principalmente ácidos graxos poli-insaturados (POLI), trans (TRANS), palmítico (PALM), palmítico interesterificado (PALM INTER), esteárico (ESTEAR) ou esteárico interesterificado (ESTEAR INTER) para determinação de concentrações plasmáticas de colesterol total e triglicérides; perfil de lipoproteínas; conteúdo de lípides (Oil Red O) e colágeno (Picrosirius Red) e infiltrado de macrófagos (imuno-histoquímica) na área de lesão aterosclerótica; expressão e conteúdo proteico de citocinas na aorta; dosagem das citocinas secretadas por macrófagos de peritônio estimulados ou não com lipopolissacarídeo (LPS); efluxo celular de colesterol mediado pela apo-AI e HDL2. Os resultados mostraram que os animais que consumiram a gordura interesterificada contendo ácido palmítico (PALM INTER) desenvolveram importante lesão aterosclerótica em comparação aos grupos PALM, ESTEAR, ESTEAR INTER e POLI, resultados confirmados pelo conteúdo de colágeno na lesão. Apesar do processo de interesterificação não ter alterado as concentrações plasmáticas de lípides, conforme verificado entre os grupos PALM vs PALM INTER e ESTEAR vs ESTEAR INTER, o acúmulo de colesterol na partícula de LDL foi similar entre os grupos PALM INTER e TRANS. Além desse efeito sobre o perfil de lipoproteínas, macrófagos do peritônio de camundongos que consumiram PALM INTER secretaram significativamente mais IL-1beta, IL-6 e MCP-1 em comparação aos demais grupos. Esse efeito pró-inflamatório foi confirmado na aorta, onde se observou maior expressão de TNF-alfa e IL-1beta para o grupo PALM INTER em comparação a PALM. Tal insulto inflamatório foi similar ao provocado por TRANS. Esses efeitos deletérios do PALM INTER podem ser parcialmente atribuídos ao acúmulo de colesterol nos macrófagos, promovido pelo prejuízo no efluxo de colesterol mediado pela apo-AI e HDL2, bem como aumento da expressão de receptores envolvidos na captação de LDL modificada (Olr-1) e diminuição daqueles envolvidos na remoção intracelular de colesterol (Abca1 e Nr1h3) na parede arterial. Como conclusão, as gorduras interesterificadas contendo ácido palmítico favorecem o acúmulo de colesterol nas partículas de LDL e em macrófagos, ativando o processo inflamatório, o que conjuntamente contribuiu para maior desenvolvimento de lesão aterosclerótica

Single-cell derived clones from human adipose stem cells present different immunomodulatory properties

Human adipose mesenchymal stem cells are a heterogeneous population, where cell cultures derived from single cell-expanded clones present varying degrees of differential plasticity. This work focuses on the immunomodulatory/anti-inflammatory properties of these cells. To this end, 5 single cell clones were isolated (generally called 1.X and 3.X) from 2 volunteers. Regarding the expression level of the lineage-characteristic surface antigens, clones 1.10 and 1.22 expressed the lowest amounts, while clones 3.10 and 3.5 expressed more CD105 than the rest and clone 1.7 expressed higher amounts of CD73 and CD44. Regarding cytokine secretion, all clones were capable of spontaneously releasing high levels of IL-6 and low to moderate levels of IL-8. These differences can be explained in part by the distinct methylation profile exhibited by the clones. Furthermore and after lipopolysaccharide stimulation, clone 3.X produced the highest amounts of pro-inflammatory cytokines such as IL-1β, while clones 1.10 and 1.22 highly expressed IL-4 and IL-5. In co-culture experiments, clones 1.X are altogether more potent inhibitors than clones 3.X for proliferation of total, CD3+T, CD4+T and CD8+T lymphocytes and NK cells. The results of this work indicates that adipose stem cell population is heterogeneous in cytokine production profile, and that isolation, characterization and selection of the appropriate cell clone is a more exact method for the possible treatment of different patients or pathologies.

Inhibition of NF-kB activation and cytokines production in THP-1 monocytes by 2-styrylchromones

Nuclear factor kappa B (NF-kB) is one of the most important transcription factors whose modulation triggers a cascade of signaling events, namely the expression of many cytokines, enzymes, chemokines, and adhesion molecules, some of which being potential key targets for intervention in the treatment of inflammatory conditions. The 2-styrylchromones (2-SC) designation represents a well-recognized group of natural and synthetic chromones, vinylogues of flavones (2-phenylchromones). Several 2-SC were recently tested for their anti-inflammatory potential, regarding the arachidonic acid metabolic cascade, showing some motivating results. In addition, several flavones with structural similarities to 2-SC have shown NF-kB inhibitory properties. Hence, the aim of the present work was to continue the investigation on the interference of 2-SC in inflammatory pathways. Herein we report their effects on lipopolysaccharide (LPS)-induced NF-kB activation and consequent production of proinflammatory cytokines/chemokine, using a human monocytic cell line (THP-1). From the twelve 2-SC tested, three of them were able to significantly inhibit the NF-kB activation and to reduce the production of the proinflammatory cytokines/chemokine. The compound 3',4',5-trihydroxy-2- styrylchromone stood up as the most active in both assays, being a promising candidate for an anti-inflammatory drug.

L’importance de la coopération de TRAF1 et LSP1 en aval du récepteur 4-1BB(CD137) pour la survie des lymphocytes

4-1BB (CD137) est un membre de la superfamille TNFR qui est impliqué dans la transmission des signaux de survie aux lymphocytes. TRAF1 est une protéine adaptatrice qui est recrutée par 4-1BB et autres TNFRs et est caractérisée par une expression très restreinte aux lymphocytes, cellules dendritiques et certaines cellules épithéliales. TRAF1 est nécessaire pour l’expansion et la survie des cellules T mémoire en présence d'agonistes anti-4-1BB in vivo. De plus, TRAF1 est requise en aval de 4-1BB pour activer (phosphoryler) la MAP kinase Erk impliquée dans la régulation de la molécule pro-apoptotique Bim. Suite à l’activation du récepteur 4-1BB, TRAF1 et ERK sont impliqués dans la phosphorylation de Bim et la modulation de son expression. L’activation et la régulation de TRAF1 et Bim ont un rôle important dans la survie des cellules T CD8 mémoires. Dans cette étude, nous avons utilisé une approche protéomique afin de pouvoir identifier de nouveaux partenaires de liaison de TRAF1. Utilisant cette stratégie, nous avons identifié que LSP1 (Leukocyte Specific Protein 1) est recruté dans le complexe de signalisation 4-1BB de manière TRAF1 dépendante. Une caractérisation plus poussée de l’interaction entre TRAF1 et LSP1 a montré que LSP1 lie la région unique N-terminal de TRAF1 de façon indépendante de la région conservée C-terminal. À l’instar des cellules T déficientes en TRAF1, les cellules T déficientes en LSP1 ne sont pas capables d’activer ERK en aval de 4-1BB et par conséquent ne peuvent pas réguler Bim. Ainsi, TRAF1 et LSP1 coopèrent en aval de 4-1BB dans le but d’activer ERK et réguler en aval les niveaux de Bim dans les cellules T CD8. Selon la littérature, le récepteur 4-1BB n’est pas exprimé à la surface des cellules B murines, mais le récepteur 4-1BB favorise la prolifération et la survie des cellules B humaines. Cependant, il est important d'étudier l'expression du récepteur 4-1BB dans les cellules B murines afin de disposer d'un modèle murin et de prédire la réponse clinique à la manipulation de 4-1BB. En utilisant différentes stimulations de cellules B murines primaires, nous avons identifié que le récepteur 4-1BB est exprimé à la surface des cellules B de souris suite à une stimulation avec le LPS (Lipopolysaccharides). Une caractérisation plus poussée a montré que le récepteur 4-1BB est induit dans les cellules B murines d'une manière dépendante de TLR4 (Toll Like Receptor 4). Collectivement, notre travail a démontré que la stimulation avec le LPS induit l’expression du récepteur 4-1BB à la surface des cellules B murines, menant ainsi à l'induction de TRAF1. De plus, TRAF1 et LSP1 coopèrent en aval de 4-1BB pour activer la signalisation de la Map kinase ERK dans les cellules B murines de manière similaire aux cellules T. Les cellules B déficientes en TRAF1 et les cellules B déficientes en LSP1 ne sont pas en mesure d'activer la voie ERK en aval de 4-1BB et montrent un niveau d’expression du récepteur significativement diminué comparé aux cellules B d’une souris WT. Ainsi, TRAF1 et LSP1 sont nécessaires pour une expression maximale du récepteur 4-1BB à la surface cellulaire de cellules B murines et coopèrent en aval de 4-1BB afin d'activer la cascade ERK dans les cellules B murines.

Characterization of B cells in healthy pregnant women from late pregnancy to post-partum: a prospective observational study

BACKGROUND: B cells play a role in pregnancy due to their humoral and regulatory activities. To our knowledge, different maturational stages (from transitional to memory) of circulating B cell subsets have not yet been characterized (cell quantification and phenotype identification) in healthy pregnant women. Thus, the objective of our study was to characterize these subsets (as well as regulatory B cells) from late pregnancy to post-partum and to compare them with the circulating B cells of non-pregnant women. METHODS: In all of the enrolled women, flow cytometry was used to characterize the circulating B cell subsets according to the expression of IgD and CD38 (Bm1-Bm5 classification system). Regulatory B cells were characterized based on the expression of surface antigens (CD24, CD27, and CD38) and the production of IL-10 after lipopolysaccharide stimulation. RESULTS: Compared to the absolute counts of B cells in the non-pregnant women (n = 35), those in the pregnant women (n = 43) were significantly lower (p < 0.05) during the 3rd trimester of pregnancy and on delivery day (immediately after delivery). The percentages of these cells on delivery day and at post-partum were significantly lower than those in the non-pregnant women. In general, the absolute counts and percentages of the majority of the B cell subsets were significantly lower in the 3rd trimester of pregnancy and on delivery day than in the non-pregnant women. However, these counts and percentages did not differ significantly between the post-partum and the non-pregnant women. The most notable exceptions to the above were the percentages of naïve B cells (which were significantly higher in the 3rd trimester and on delivery day than in the non-pregnant women) and of CD24(hi)CD38(hi) regulatory B cells (which were significantly higher in the post-partum than in the non-pregnant women). CONCLUSION: According to our study, the peripheral B cell compartment undergoes quantitative changes during normal late pregnancy and post-partum. Such findings may allow us to better understand immunomodulation during human pregnancy and provide evidence that could aid in the development of new strategies to diagnose and treat pregnancy-associated disturbances. Our findings could also be useful for studies of the mechanisms of maternal responses to vaccination and infection.

Characterization of B cells in healthy pregnant women from late pregnancy to post-partum: a prospective observational study

Abstract BACKGROUND: B cells play a role in pregnancy due to their humoral and regulatory activities. To our knowledge, different maturational stages (from transitional to memory) of circulating B cell subsets have not yet been characterized (cell quantification and phenotype identification) in healthy pregnant women. Thus, the objective of our study was to characterize these subsets (as well as regulatory B cells) from late pregnancy to post-partum and to compare them with the circulating B cells of non-pregnant women. METHODS: In all of the enrolled women, flow cytometry was used to characterize the circulating B cell subsets according to the expression of IgD and CD38 (Bm1-Bm5 classification system). Regulatory B cells were characterized based on the expression of surface antigens (CD24, CD27, and CD38) and the production of IL-10 after lipopolysaccharide stimulation. RESULTS: Compared to the absolute counts of B cells in the non-pregnant women (n = 35), those in the pregnant women (n = 43) were significantly lower (p < 0.05) during the 3rd trimester of pregnancy and on delivery day (immediately after delivery). The percentages of these cells on delivery day and at post-partum were significantly lower than those in the non-pregnant women. In general, the absolute counts and percentages of the majority of the B cell subsets were significantly lower in the 3rd trimester of pregnancy and on delivery day than in the non-pregnant women. However, these counts and percentages did not differ significantly between the post-partum and the non-pregnant women. The most notable exceptions to the above were the percentages of naïve B cells (which were significantly higher in the 3rd trimester and on delivery day than in the non-pregnant women) and of CD24(hi)CD38(hi) regulatory B cells (which were significantly higher in the post-partum than in the non-pregnant women). CONCLUSION: According to our study, the peripheral B cell compartment undergoes quantitative changes during normal late pregnancy and post-partum. Such findings may allow us to better understand immunomodulation during human pregnancy and provide evidence that could aid in the development of new strategies to diagnose and treat pregnancy-associated disturbances. Our findings could also be useful for studies of the mechanisms of maternal responses to vaccination and infection.