Effect of breastfeeding and formula feeding on transmission of HIV-1: a randomized clinical trial

CONTEXT

Transmission of human immunodeficiency virus type 1 (HIV-1) is known to occur through breastfeeding, but the magnitude of risk has not been precisely defined. Whether breast milk HIV-1 transmission risk exceeds the potential risk of formula-associated diarrheal mortality in developing countries is unknown.

OBJECTIVES

To determine the frequency of breast milk transmission of HIV-1 and to compare mortality rates and HIV-1-free survival in breastfed and formula-fed infants.

DESIGN AND SETTING

Randomized clinical trial conducted from November 1992 to July 1998 in antenatal clinics in Nairobi, Kenya, with a median follow-up period of 24 months.

PARTICIPANTS

Of 425 HIV-1-seropositive, antiretroviral-naive pregnant women enrolled, 401 mother-infant pairs were included in the analysis of trial end points.

INTERVENTIONS

Mother-infant pairs were randomized to breastfeeding (n = 212) vs formula feeding arms (n = 213).

MAIN OUTCOME MEASURES

Infant HIV-1 infection and death during the first 2 years of life, compared between the 2 intervention groups.

RESULTS

Compliance with the assigned feeding modality was 96% in the breastfeeding arm and 70% in the formula arm (P<.001). Median duration of breastfeeding was 17 months. Of the 401 infants included in the analysis, 94% were followed up to HIV-1 infection or mortality end points: 83% for the HIV-1 infection end point and 93% to the mortality end point. The cumulative probability of HIV-1 infection at 24 months was 36.7% (95% confidence interval [CI], 29.4%-44.0%) in the breastfeeding arm and 20.5% (95% CI, 14.0%-27.0%) in the formula arm (P = .001). The estimated rate of breast milk transmission was 16.2% (95% CI, 6.5%-25.9%). Forty-four percent of HIV-1 infection in the breastfeeding arm was attributable to breast milk. Most breast milk transmission occurred early, with 75% of the risk difference between the 2 arms occurring by 6 months, although transmission continued throughout the duration of exposure. The 2-year mortality rates in both arms were similar (breastfeeding arm, 24.4% [95% CI, 18.2%-30.7%] vs formula feeding arm, 20.0% [95% CI, 14.4%-25.6%]; P = .30). The rate of HIV-1-free survival at 2 years was significantly lower in the breastfeeding arm than in the formula feeding arm (58.0% vs 70.0%, respectively; P = .02).

CONCLUSIONS

The frequency of breast milk transmission of HIV-1 was 16.2% in this randomized clinical trial, and the majority of infections occurred early during breastfeeding. The use of breast milk substitutes prevented 44% of infant infections and was associated with significantly improved HIV-1-free survival.

Evidence for impaired T cell DNA methylation in systemic lupus erythematosus and rheumatoid arthritis

Procainamide and hydralazine inhibit T cell DNA methylation and induce autoreactivity in cloned CD4+ T cells. These drugs also induce an autoimmune syndrome, suggesting a possible relationship between DNA hypomethylation, T cell autoreactivity, and certain autoimmune diseases. To test this relationship, DNA methylation was studied in T cells from patients with rheumatoid arthritis and patients with systemic lupus erythematosus, and was found to be impaired. These results support a relationship between DNA hypomethylation and some forms of autoimmune disease.

Patterns of gross fetal body movements over 24-hour observation intervals during the last 10 weeks of pregnancy

Continuous measurements of gross fetal body movements were made with an ultrasonic real-time scanner for periods of 24 hours in 31 women. Fetuses made 0 to 130 gross fetal body movements per hour which accounted for 0% to 50% of the time. At 38 to 39 weeks' gestational age, fetuses demonstrated a peak in activity between 2100 and 0100 hours. The longest period of complete absence of gross fetal body movements was 75 minutes. Maternal meals and glucose concentrations did not influence gross fetal body movements.

Demethylation of CD40LG on the inactive X in T cells from women with lupus

Why systemic lupus erythematosus primarily affects women is unknown. Recent evidence indicates that human lupus is an epigenetic disease characterized by impaired T cell DNA methylation. Women have two X chromosomes; one is inactivated by mechanisms including DNA methylation. We hypothesized that demethylation of sequences on the inactive X may cause gene overexpression uniquely in women, predisposing them to lupus. We therefore compared expression and methylation of CD40LG, a B cell costimulatory molecule encoded on the X chromosome, in experimentally demethylated T cells from men and women and in men and women with lupus. Controls included TNFSF7, a methylation-sensitive autosomal B cell costimulatory molecule known to be demethylated and overexpressed in lupus. Bisulfite sequencing revealed that CD40LG is unmethylated in men, while women have one methylated and one unmethylated gene. 5-Azacytidine, a DNA methyltransferase inhibitor, demethylated CD40LG and doubled its expression on CD4(+) T cells from women but not men, while increasing TNFSF7 expression equally between sexes. Similar studies demonstrated that CD40LG demethylates in CD4(+) T cells from women with lupus, and that women but not men with lupus overexpress CD40LG on CD4(+) T cells, while both overexpress TNFSF7. These studies demonstrate that regulatory sequences on the inactive X chromosome demethylate in T cells from women with lupus, contributing to CD40LG overexpression uniquely in women. Demethylation of CD40LG and perhaps other genes on the inactive X may contribute to the striking female predilection of this disease.

Impact of aging on DNA methylation

The biochemistry of aging is complex, with biologically significant changes occurring in proteins, lipids and nucleic acids. One of these changes is in the methylation of DNA. DNA methylation is a mechanism modifying gene expression. The methylation of sequences in or near regulatory elements can suppress gene expression through effects on DNA binding proteins and chromatin structure. Both increases and decreases in methylation occur with aging, depending on the tissue and the gene. These changes can have pathologic consequences, contributing to the development of malignancies and autoimmunity with aging, and possibly to other disorders as well. Thus, while aging can impact on DNA methylation, the changes in DNA methylation can also impact on aging. This review summarizes current evidence for changes in the methylation status of specific genes with aging, their impact on diseases that develop with aging, and mechanisms that may contribute to the altered DNA methylation patterns. As this field is still developing, it is anticipated that new knowledge will continue to accumulate rapidly.

Treating activated CD4+ T cells with either of two distinct DNA methyltransferase inhibitors, 5-azacytidine or procainamide, is sufficient to cause a lupus-like disease in syngeneic mice

Human antigen-specific CD4+ T cells become autoreactive after treatment with various DNA methylation inhibitors, including 5-azacytidine, procainamide, and hydralazine. This suggests a mechanism that could contribute to the development of some forms of autoimmunity. In this report we have asked whether T cells treated with DNA methylation inhibitors can induce autoimmunity. Murine CD4+ T cells were treated with 5-azacytidine or procainamide and were shown to respond to syngeneic antigen-presenting cells, similar to CD4+ human T cell clones treated with these drugs. Functional characterization demonstrated that cells treated with either drug spontaneously lysed syngeneic macrophages and secreted IL-4, IL-6, and IFN-gamma. Adoptive transfer of 5-azacytidine- or procainamide-treated cells into unirradiated syngeneic recipients induced an immune complex glomerulonephritis and IgG anti-DNA and antihistone antibodies. These experiments demonstrate that T cells treated with either of two distinct DNA methyltransferase inhibitors are sufficient to induce a lupus-like disease. It is possible that the lysis of macrophages, together with the release of cytokines promoting B cell differentiation, contributes to the autoantibody production and immune complex deposition. These results suggest that environmental agents that inhibit DNA methylation could interact with T cells in vivo to produce a lupus-like illness, a mechanism that could have relevance to drug-induced and idiopathic lupus.

Demethylation of ITGAL (CD11a) regulatory sequences in systemic lupus erythematosus

OBJECTIVE

Inhibition of T cell DNA methylation causes autoreactivity in vitro and a lupus-like disease in vivo, suggesting that T cell DNA hypomethylation may contribute to autoimmunity. The hypomethylation effects are due, in part, to overexpression of lymphocyte function-associated antigen 1 (LFA-1) (CD11a/CD18). Importantly, T cells from patients with active lupus have hypomethylated DNA and overexpress LFA-1 on an autoreactive subset, suggesting that the same mechanism could contribute to human lupus. The present study investigated the nature of the methylation change that affects LFA-1 expression in vitro and in human lupus.

METHODS

Bisulfite sequencing was used to determine the methylation status of the ITGAL promoter and flanking regions in T cells from lupus patients and healthy subjects, and in T cells treated with DNA methylation inhibitors. "Patch" methylation of promoter sequences in reporter constructs was used to determine the functional significance of the methylation changes.

RESULTS

Hypomethylation of specific sequences flanking the ITGAL promoter was seen in T cells from patients with active lupus and in T cells treated with 5-azacytidine and procainamide. Patch methylation of this region suppressed ITGAL promoter function.

CONCLUSION

DNA methylation changes occur in specific sequences that regulate LFA-1 expression in lupus T cells and in the hypomethylation model, indicating that altered methylation of specific genes may play a role in the pathogenesis of lupus.

Stronger inflammatory/cytotoxic T-cell response in women identified by microarray analysis

Women develop chronic inflammatory autoimmune diseases more often than men. The mechanisms causing the increased susceptibility are incompletely understood. Chronic immune stimulation characterizes many autoimmune disorders. We hypothesized that repeated stimulation may cause a different T cell response in women than men. Microarrays were used to compare gene expression in T cells from healthy men and women with and without repeated stimulation. Four days following a single stimulation only 25% of differentially expressed, gender-biased genes were expressed at higher levels in women. In contrast, following restimulation 72% were more highly expressed in women. Immune response genes were significantly over-represented among the genes upregulated in women and among the immune response genes, the inflammatory/cytotoxic effector genes interferon gamma (IFNG), lymphotoxin beta (LTB), granzyme A (GZMA), interleukin-12 receptor beta2 (IL12RB2), and granulysin (GNLY) were among those overexpressed to the greatest degree. In contrast, IL17A was the only effector gene more highly expressed in men. Estrogen response elements were identified in the promoters of half the overexpressed immune genes in women, and in <10% of the male biased genes. The differential expression of inflammatory/cytotoxic effector molecules in restimulated female T cells may contribute to the differences in autoimmune diseases between women and men.

Demethylation of the same promoter sequence increases CD70 expression in lupus T cells and T cells treated with lupus-inducing drugs

Exposing genetically predisposed individuals to certain environmental agents is believed to cause human lupus. How environmental agents interact with the host to cause lupus is poorly understood. Procainamide and hydralazine are drugs that cause lupus in genetically predisposed individuals. Understanding how these environmental agents cause lupus may indicate mechanisms relevant to the idiopathic disease. Abnormal T cell DNA methylation, a repressive epigenetic DNA modification, is implicated in procainamide and hydralazine induced lupus, as well as idiopathic lupus. Procainamide is a competitive DNA methyltransferase (Dnmt) inhibitor, hydralazine inhibits ERK pathway signaling thereby decreasing Dnmt expression, and in lupus T cells decreased ERK pathway signaling causing a similar Dnmt decrease. T cells treated with procainamide, hydralazine, and other Dnmt and ERK pathway inhibitors cause lupus in mice. Whether the same genetic regulatory elements demethylate in T cells treated with Dnmt inhibitors, ERK pathway inhibitors, and in human lupus is unknown. CD70 (TNFSF7) is a B cell costimulatory molecule overexpressed on CD4(+) lupus T cells as well as procainamide and hydralazine treated T cells, and contributes to excessive B cell stimulation in vitro and in lupus. In this report we identify a genetic element that suppresses CD70 expression when methylated, and which demethylates in lupus and in T cells treated with Dnmt and ERK pathway inhibitors including procainamide and hydralazine. The results support a model in which demethylation of specific genetic elements in T cells, caused by decreasing Dnmt expression or inhibiting its function, contributes to drug-induced and idiopathic lupus through altered gene expression.

Hydralazine may induce autoimmunity by inhibiting extracellular signal-regulated kinase pathway signaling

OBJECTIVE

To determine whether hydralazine might decrease DNA methyltransferase (DNMT) expression and induce autoimmunity by inhibiting extracellular signal-regulated kinase (ERK) pathway signaling.

METHODS

The effect of hydralazine on DNMT was tested in vitro using enzyme inhibition studies, and in vivo by measuring messenger RNA (mRNA) levels and enzyme activity. Effects on ERK, c-Jun N-terminal kinase, and p38 pathway signaling were tested using immunoblotting. Murine T cells treated with hydralazine or an ERK pathway inhibitor were injected into mice and anti-DNA antibodies were measured by enzyme-linked immunosorbent assay.

RESULTS

In vitro, hydralazine did not inhibit DNMT activity. Instead, hydralazine inhibited ERK pathway signaling, thereby decreasing DNMT1 and DNMT3a mRNA expression and DNMT enzyme activity similar to mitogen-activated protein kinase kinase (MEK) inhibitors. Inhibiting T cell ERK pathway signaling with an MEK inhibitor was sufficient to induce anti-double-stranded DNA antibodies in a murine model of drug-induced lupus, similar to the effect of hydralazine.

CONCLUSION

Hydralazine reproduces the lupus ERK pathway signaling abnormality and its effects on DNMT expression, and inhibiting this pathway induces autoimmunity. Hydralazine-induced lupus could be caused in part by inducing the same ERK pathway signaling defect that occurs in idiopathic lupus.

Demethylation of promoter regulatory elements contributes to perforin overexpression in CD4+ lupus T cells

Inhibiting DNA methylation in CD4+ T cells causes aberrant gene expression and autoreactive monocyte/macrophage killing in vitro, and the hypomethylated cells cause a lupus-like disease in animal models. Similar decreases in T cell DNA methylation occur in idiopathic lupus, potentially contributing to disease pathogenesis. The genes affected by DNA hypomethylation are largely unknown. Using DNA methylation inhibitors and oligonucleotide arrays we have identified perforin as a methylation-sensitive gene. Our group has also reported that DNA methylation inhibitors increase CD4+ T cell perforin by demethylating a conserved methylation-sensitive region that is hypomethylated in primary CD8+ cells, which express perforin, but is largely methylated in primary CD4+ cells, which do not. As lupus T cells also have hypomethylated DNA and promiscuously kill autologous monocytes/macrophages, we hypothesized that perforin may be similarly overexpressed in lupus T cells and contribute to the monocyte killing. We report that CD4+ T cells from patients with active, but not inactive, lupus overexpress perforin, and that overexpression is related to demethylation of the same sequences suppressing perforin transcription in primary CD4+ T cells and demethylated by DNA methylation inhibitors. Further, the perforin inhibitor concanamycin A blocks autologous monocyte killing by CD4+ lupus T cells, suggesting that the perforin is functional. We conclude that demethylation of specific regulatory elements contributes to perforin overexpression in CD4+ lupus T cells. Our results also suggest that aberrant perforin expression in CD4+ lupus T cells may contribute to monocyte killing.

Decreased Ras-mitogen-activated protein kinase signaling may cause DNA hypomethylation in T lymphocytes from lupus patients

OBJECTIVE

Previous studies have shown that inhibiting T cell DNA methylation causes a lupus-like disease by modifying gene expression. T cells from patients with lupus exhibit diminished levels of DNA methyltransferase (MTase) enzyme activity, hypomethylated DNA, and changes in gene expression similar to those exhibited by T cells treated with methylation inhibitors, suggesting that DNA hypomethylation may contribute to human lupus. Since it is known that DNA MTase levels are regulated by the ras-mitogen-activated protein kinase (MAPK) pathway, this study sought to determine whether decreased ras-MAPK signaling could account for the DNA hypomethylation in lupus T cells.

METHODS

DNA MTase messenger RNA (mRNA) from lupus patients and from healthy controls was quantitated by Northern analysis, and ras-MAPK signaling was determined by immunoblotting with antibodies to the activated forms of extracellular receptor-associated kinase (ERK). Results were compared with those in T cells in which ras-MAPK signaling was inhibited with a soluble inhibitor of MAPK ERK I (MEK1).

RESULTS

T cells from patients with active lupus had diminished DNA MTase mRNA levels and decreased signaling through the ras-MAPK pathway. Inhibiting signaling through the ras-MAPK pathway with the MEK1 inhibitor decreased DNA MTase mRNA and enzyme activity to the levels seen in lupus T cells, and resulted in DNA hypomethylation resembling that seen in lupus T cells.

CONCLUSION

These results suggest that a decrease in signaling through the ras-MAPK pathway may be responsible for the decreased MTase activity and DNA hypomethylation in patients with lupus.

Endothelial cell apoptosis in systemic lupus erythematosus: a common pathway for abnormal vascular function and thrombosis propensity

Women with systemic lupus erythematosus (SLE) are at risk for premature atherothrombosis independent of Framingham risk factors. We investigated whether endothelial cell (EC) apoptosis predicts abnormal vasomotor tone and contributes to circulating tissue factor (TF) levels in this disease. Brachial artery flow-mediated dilation (FMD) and nitroglycerin-mediated dilation were determined in women with SLE, healthy control subjects, and subjects with coronary artery disease (CAD) (n = 43/group). Quantification of circulating apoptotic ECs was performed by flow cytometry (CD146+ cells that stained for Annexin V [CD146AnnV+]) and immunofluorescent microscopy. Plasma TF was measured by enzyme-linked immunosorbent assay (ELISA). Compared with healthy control and CAD subjects, patients with SLE had higher numbers of circulating CD146AnnV+ cells (10 ± 3, 18 ± 5, and 89 ± 32 cells/mL, respectively, mean ± SEM; P &lt; .01). Increased CD146AnnV+ cells correlated strongly with abnormal vascular function (P = .037). After adjusting for known predictors of endothelial function, CD146AnnV+ was the only variable that predicted FMD (β = –4.5, P &lt; .001). Increased CD146AnnV+ was strongly associated with elevated levels of circulating TF (r = .46, P = .002). Circulating apoptotic ECs are elevated in young women with SLE and strongly correlate with markedly abnormal vascular function and elevated TF levels. Heightened endothelial apoptosis may represent an important mechanism for development of atherothrombosis in SLE.

Overexpression of CD70 and overstimulation of IgG synthesis by lupus T cells and T cells treated with DNA methylation inhibitors

OBJECTIVE

Generalized DNA hypomethylation contributes to altered T cell function and gene expression in systemic lupus erythematosus (SLE). Some of the overexpressed genes participate in the disease process, but the full repertoire of genes affected is unknown. Methylation-sensitive T cell genes were identified by treating T cells with the DNA methyltransferase inhibitor 5-azacytidine and comparing gene expression with oligonucleotide arrays. CD70, a costimulatory ligand for B cell CD27, was one gene that reproducibly increased. We then determined whether CD70 is overexpressed on T cells treated with other DNA methylation inhibitors and on SLE T cells, and determined its functional significance.

METHODS

Oligonucleotide arrays, real-time reverse transcription-polymerase chain reaction, and flow cytometry were used to compare CD70 expression in T cells treated with 2 DNA methyltransferase inhibitors (5-azacytidine and procainamide) and 3 ERK pathway inhibitors known to decrease DNA methyltransferase expression (U0126, PD98059, and hydralazine). The consequences of CD70 overexpression were tested by coculture of autologous T and B cells with and without anti-CD70 and measuring IgG production by enzyme-linked immunosorbent assay. The results were compared with those of T cells from lupus patients.

RESULTS

SLE T cells and T cells treated with DNA methylation inhibitors overexpressed CD70 and overstimulated B cell IgG production. The increase in IgG synthesis was abrogated by anti-CD70.

CONCLUSION

SLE T cells and T cells treated with DNA methyltransferase inhibitors and ERK pathway inhibitors overexpress CD70. This increased B cell costimulation and subsequent immunoglobulin overproduction may contribute to drug-induced and idiopathic lupus.

Assault experiences of 100 psychiatric inpatients: evidence of the need for routine inquiry

The authors obtained complete histories of all experiences of being physically or sexually assaulted from 100 psychiatric inpatients, using a structured interview with well-defined assault scales and a detailed inquiry into circumstances surrounding the assault. The majority (81%) of patients had experienced major physical and/or sexual assault. The circumstances associated with the assaults, the patients' perceptions of the effects of the assaults, and previous therapists' lack of awareness of the assaults are discussed. On the basis of these findings the authors recommend routine inquiry into patients' assault history.

Overexpression of X-linked genes in T cells from women with lupus

Women develop lupus more frequently than men and the reason remains incompletely understood. Evidence that men with Klinefelter's Syndrome (XXY) develop lupus at approximately the same rate as women suggests that a second X chromosome contributes. However, since the second X is normally inactivated, how it predisposes to lupus is unclear. DNA methylation contributes to the silencing of one X chromosome in women, and CD4+ T cell DNA demethylation contributes to the development of lupus-like autoimmunity. This suggests that demethylation of genes on the inactive X may predispose women to lupus, and this hypothesis is supported by a report that CD40LG, an immune gene encoded on the X chromosome, demethylates and is overexpressed in T cells from women but not men with lupus. Overexpression of other immune genes on the inactive X may also predispose women to this disease. We therefore compared mRNA and miRNA expression profiles in experimentally demethylated T cells from women and men as well as in T cells from women and men with lupus. T cells from healthy men and women were treated with the DNA methyltransferase inhibitor 5-azacytidine, then X-linked mRNAs were surveyed with oligonucleotide arrays, and X-linked miRNA's surveyed with PCR arrays. CD40LG, CXCR3, OGT, miR-98, let-7f-2*, miR 188-3p, miR-421 and miR-503 were among the genes overexpressed in women relative to men. MiRNA target prediction analyses identified CBL, which downregulates T cell receptor signaling and is decreased in lupus T cells, as a gene targeted by miR-188-3p and miR-98. Transfection with miR-98 and miR-188-3p suppressed CBL expression. The same mRNA and miRNA transcripts were also demethylated and overexpressed in CD4+ T cells from women relative to men with active lupus. Together these results further support a role for X chromosome demethylation in the female predisposition to lupus.

Role of DNA methylation in the regulation of cell function: autoimmunity, aging and cancer

DNA methylation plays an essential role in maintaining cellular function, and changes in methylation patterns may contribute to the development of autoimmunity, aging and cancer. Evidence for a role in autoimmunity comes from studies demonstrating that inhibiting T lymphocyte DNA methylation causes autoreactivity in vitro and a lupus-like disease in vivo. The autoimmunity is due in part to the heterodimeric beta(2) integrin lymphocyte function-associated antigen-1 (LFA-1) (CD11a/CD18) overexpression, and T lymphocytes from lupus patients hypomethylate the same CD11a promoter sequences, overexpress LFA-1 and demonstrate the same autoreactivity. Procainamide and hydralazine, two drugs that cause a lupus-like disease, also inhibit T cell DNA methylation, increase LFA-1 expression and induce autoreactivity in vitro and autoimmunity in vivo, supporting the association of DNA hypomethylation and autoimmunity. Methylation patterns also change with age in T lymphocytes as well as other tissues, typically with an overall decrease in methylcytosine content, but with increases in some cytosine guanine dinucleotide (CpG) islands. Age-dependent hypomethylation contributes to LFA-1 overexpression with aging, which may play a role in the development of autoimmunity in the elderly and age-dependent methylation of CpG islands in the promoters of tumor suppressor genes is an early event in the development of some cancers. DNA hypomethylation also may contribute to carcinogenesis by promoting overexpression of proto-oncogenes, chromosomal translocations and loss of imprinting. The mechanisms causing altered DNA methylation in autoimmunity, aging and carcinogenesis are incompletely characterized but include exposure to environmental agents and drugs, diet, altered signaling in pathways regulating DNA methyltransferase expression and changes in endogenous regulatory mechanisms. Other mechanisms are likely to be identified as well.

Mechanisms of drug-induced lupus. II. T cells overexpressing lymphocyte function-associated antigen 1 become autoreactive and cause a lupuslike disease in syngeneic mice

Current theories propose that systemic lupus erythematosus develops when genetically predisposed individuals are exposed to certain environmental agents, although how these agents trigger lupus is uncertain. Some of these agents, such as procainamide, hydralazine, and UV-light inhibit T cell DNA methylation, increase lymphocyte function-associated antigen 1 (LFA-1) (CD11a/CD18) expression, and induce autoreactivity in vitro, and adoptive transfer of T cells that are made autoreactive by this mechanism causes a lupuslike disease. The mechanism by which these cells cause autoimmunity is unknown. In this report, we present evidence that LFA-1 overexpression is sufficient to induce autoimmunity. LFA-1 overexpression was induced on cloned murine Th2 cells by transfection, resulting in autoreactivity. Adoptive transfer of the transfected, autoreactive cells into syngeneic recipients caused a lupuslike disease with anti-DNA antibodies, an immune complex glomerulonephritis and pulmonary alveolitis, similar to that caused by cells treated with procainamide. These results indicate that agents or events which modify T cell DNA methylation may induce autoimmunity by causing T cell LFA-1 overexpression. Since T cells from patients with active lupus have hypomethylated DNA and overexpressed LFA-1, this mechanism could be important in the development of human autoimmunity.

Study of the contractile effect of 5-hydroxytryptamine (5-HT) in the isolated longitudinal muscle strip from guinea-pig ileum. Evidence for two distinct release mechanisms

The contractile effect of 5-HT in the isolated longitudinal ileal muscle of adult guinea-pigs was studied over a large concentration range. 5-HT produced a biphasic concentration-response curve indicative of an interaction with at least two independent populations of receptors. The concentrations which elicited half-maximal effects for the first and the second phases of the concentration-response curve were estimated as 1.5 +/- 1.2 X 10(-8) mol/l and 1.3 +/- 0.4 X 10(-6) mol/l respectively. The maximal response produced by the interaction of 5-HT with the high affinity receptor (i.e. first phase) was calculated as 27 +/- 9.3% of the total response. The biphasic concentration-response was not influenced by methysergide (10(-6) mol/l). The effect of low concentrations of 5-HT (less than 3 X 10(-7) mol/l) was antagonised by atropine (10(-7) mol/l), tetrodotoxin (TTX) (10(-6) mol/l), morphine (10(-5) mol/l), the substance P antagonist, D-Pro4,D-Trp7,9-SP4-11 (3 X 10(-5) mol/l) and capsaicin (10(-5) mol/l). Physostigmine (10(-7) mol/l) augmented the effect. The response to high concentrations of 5-HT (3 X 10(-7)-3 X 10(-6) mol/l) was antagonised by ICS 205-930 and D-Pro4,D-Trp7,9-SP4-11 in a competitive manner and was inhibited by TTX, morphine and capsaicin in an insurmountable way. The effect of very high concentrations of 5-HT (greater than 10(-5) mol/l) could be partially antagonised by methysergide (10(-7) mol/l) in the presence of ICS 205-930 (10(-7) mol/l) and totally by a combination of methysergide and TTX.(ABSTRACT TRUNCATED AT 250 WORDS)

DNA methylation and autoimmune disease

DNA methylation plays an essential role in maintaining T-cell function. A growing body of literature indicates that failure to maintain DNA methylation levels and patterns in mature T cells can result in T-cell autoreactivity in vitro and autoimmunity in vivo. Defective maintenance of DNA methylation may be caused by drugs such as procainamide or hydralazine, or failure to activate the genes encoding maintenance DNA methyltransferases during mitosis, resulting in the development of a lupus-like disease or perhaps other autoimmune disorders. This paper reviews the evidence supporting a role for abnormal T-cell DNA methylation in causing autoimmunity in an animal model of drug-induced lupus, and discusses some of the mechanisms involved. T cells from patients with active lupus have evidence for most if not all of the same methylation abnormalities, suggesting that abnormal DNA methylation plays a role in idiopathic human lupus as well.

Fas ligation triggers apoptosis in macrophages but not endothelial cells

The reticuloendothelial system includes macrophages and endothelial cells. These cells are produced and destroyed in vivo with a precision that implies the existence of homeostatic mechanisms. The stimuli for endothelial cell proliferation and monocyte production are becoming well characterized. However, the mechanisms involved in eliminating these cells are poorly understood. One mechanism involved in cellular elimination is apoptosis, which can be triggered in some cells by ligation of the Fas molecule. In this report we have investigated whether macrophages and endothelial cells express the Fas molecule, and whether Fas transmits an apoptosis-inducing signal in these cells. We demonstrate that macrophages express Fas and readily undergo apoptosis when cultured with anti-Fas. In contrast, while endothelial cells can express the Fas molecule, Fas ligation is insufficient to induce apoptosis. These results suggest differential regulation of Fas function among cells of the reticuloendothelial system, and imply different mechanisms of homeostasis.

The risks of spontaneous preterm delivery and perinatal mortality in relation to size at birth according to fetal versus neonatal growth standards

OBJECTIVE

The aim of this study was to test the null hypothesis that size at birth relative to fetal or neonatal growth standards is not a significant variable related to the risk of spontaneous preterm delivery.

STUDY DESIGN

This was a hospital-based cohort study of consecutive births at a tertiary care perinatal center from January 1, 1985, to December 31, 1996. A total of 37,377 pregnancies met the following inclusion criteria: (1) singleton gestation, (2) 25 to 40 weeks' gestation, and (3) no anomalies. Neonates were divided into 5 birth weight categories according to either fetal (uncorrected for sex) or neonatal (corrected for sex) growth standards, as follows: (1) intrauterine growth restriction, birth weight <3rd percentile; (2) borderline intrauterine growth restriction, birth weight > or = 3rd percentile and <10th percentile; (3) appropriate for gestational age, birth weight from 10th percentile through 90th percentile; (4) borderline large for gestational age, birth weight >90th percentile but < or = 97th percentile, and (5) large for gestational age, birth weight >97th percentile. Logistic regression analysis was used to estimate the independent effect of birth weight category on the risk of preterm delivery after spontaneous onset of labor, with the appropriate-for-gestational-age group serving as a reference.

RESULTS

When fetal growth standards were applied, there was a significant increase in the risk of spontaneous preterm delivery when birth weight was outside the appropriate-for-gestational-age range (odds ratios of 2.5, 1.4, 1.2, and 1.9 for intrauterine growth restriction, borderline intrauterine growth restriction, borderline large-for-gestational age, and large-for-gestational-age groups, respectively). In contrast, when neonatal growth standards were applied, the risks of spontaneous preterm delivery in intrauterine growth restriction, borderline intrauterine growth restriction, and large-for-gestational-age groups were significantly lower (odds ratios of 0.5, 0.7, and 0.7 for intrauterine growth restriction, borderline intrauterine growth restriction, and large-for-gestational-age groups, respectively) because of an underestimation in the number of fetuses with abnormal size at birth delivered prematurely. With both fetal and neonatal growth standards there was a 5-to 6-fold greater risk of perinatal death for both preterm and term fetuses with intrauterine growth restriction.

CONCLUSION

Fetal growth standards are more appropriate in predicting the impact of birth weight category on the risk of spontaneous preterm delivery than are neonatal growth standards. When fetal standards are applied, the risks of preterm birth in both extreme abnormal birth weight categories (intrauterine growth restriction and large for gestational age) are 2- to 3-fold greater than the risk among appropriate-for-gestational-age infants.

Phenotypic and functional similarities between 5-azacytidine-treated T cells and a T cell subset in patients with active systemic lupus erythematosus

OBJECTIVE

Antigen-specific CD4+ T cells treated with DNA methylation inhibitors become autoreactive, suggesting a novel mechanism for autoimmunity. To test whether this mechanism might be involved in systemic lupus erythematosus (SLE), phenotypic markers for the autoreactive cells were sought.

METHODS

Cloned normal T cells were treated with the DNA methylation inhibitor 5-azacytidine (5-azaC) and studied for altered gene expression. T cells from patients with active SLE were then studied for a similar change in gene expression, and cells expressing the marker were tested for autoreactivity.

RESULTS

5-azaC-treated normal T cells had increased CD11a (leukocyte function-associated antigen 1 alpha) expression relative to other membrane molecules. A T cell subset with similar CD11a expression was found in patients with active SLE. This subset contained cells that spontaneously lysed autologous macrophages, with a specificity similar to that of 5-azaC-treated cells.

The apoptotic ligands TRAIL, TWEAK, and Fas ligand mediate monocyte death induced by autologous lupus T cells

Individuals with systemic lupus erythematosus show evidence of a significant increase in monocyte apoptosis. This process is mediated, at least in part, by an autoreactive T cell subset that kills autologous monocytes in the absence of nominal Ag. We have investigated the apoptotic pathways involved in this T cell-mediated process. Expression of the apoptotic ligands TRAIL, TNF-like weak inducer of apoptosis (TWEAK), and Fas ligand on lupus T cells was determined, and the role of these molecules in the monocyte apoptotic response was examined. We report that these apoptotic ligands mediate the autologous monocyte death induced by lupus T cells and that this cytotoxicity is associated with increased expression of these molecules on activated T cells, rather than with an increased susceptibility of lupus monocytes to apoptosis induced by these ligands. These results define novel mechanisms that contribute to increased monocyte apoptosis characterizing patients with lupus. We propose that this mechanism could provide a source of potentially antigenic material for the autoimmune response and interfere with normal clearing mechanisms.

The epigenetic face of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an archetypical systemic, autoimmune inflammatory disease characterized by the production of autoantibodies to multiple nuclear Ags. Apoptotic defects and impaired removal of apoptotic cells contribute to an overload of autoantigens that become available to initiate an autoimmune response. Besides the well-recognized genetic susceptibility to SLE, epigenetic factors are important in the onset of the disease, as even monozygotic twins are usually discordant for the disease. Changes in DNA methylation and histone modifications, the major epigenetic marks, are a hallmark in genes that undergo epigenetic deregulation in disease. In SLE, global and gene-specific DNA methylation changes have been demonstrated to occur. Moreover, histone deacetylase inhibitors reverse the skewed expression of multiple genes involved in SLE. In the present study, we discuss the implications of epigenetic alterations in the development and progression of SLE and how epigenetic drugs constitute a promising source of therapy to treat this disease.