Effect of dexamethasone on IL-2 and IL-3 production by mononuclear cells in neonates and adults

Dexamethasone prophylaxis protects from acute high-altitude illness by modifying the peripheral blood mononuclear cell inflammatory transcriptome

Acute high-altitude (HA) exposure can induce several pathologies. Dexamethasone (DEX) can be taken prophylactically to prevent HA disease, but the mechanism by which it acts in this setting is unclear. We studied the transcriptome of peripheral blood mononuclear cells (PBMCs) from 16 subjects at low altitude (LA, 225 m) and then 3 days after acute travel to HA (3500 m) during the India-Leh-Dexamethasone-Expedition-2020 (INDEX2020). Half of the participants received oral DEX prophylaxis 4 mg twice daily in an unblinded manner, starting 1 day prior to travel to HA, and 12 h prior to the first PBMC collection. PBMC transcriptome data were obtained from 16 subjects, half of whom received DEX. The principal component analysis demonstrated a clear separation of the groups by altitude and treatment. HA exposure resulted in a large number of gene expression changes, particularly in pathways of inflammation or the regulation of cell division, translation, or transcription. DEX prophylaxis resulted in changes in fewer genes, particularly in immune pathways. The gene sets modulated by HA and DEX were distinct. Deconvolution analysis to assess PBMC subpopulations suggested changes in B-cell, T-cell, dendritic cell, and myeloid cell numbers with HA and DEX exposures. Acute HA travel and DEX prophylaxis induce significant changes in the PBMC transcriptome. The observed benefit of DEX prophylaxis against HA disease may be mediated by suppression of inflammatory pathways and changing leukocyte population distributions.

A comparison of the effect of vitamin A on cytokine secretion by mononuclear cells of preterm newborns and adults

BACKGROUND

For a long time vitamin A has been known to be essential for immune defense of the organism and protection against infections. Vitamin A deficiency in children is associated with morbidity and mortality from infectious diseases which could be prevented and even alleviated by vitamin A supplementation. Moreover, this vitamin is involved in the modulation of immunological and inflammatory responses by regulation of cytokine production. The aim of the study was to compare the in vitro effect of vitamin A on the production of pro-inflammatory (IL-1beta and IL-6) and anti-inflammatory (IL-1 receptor antagonist (ra) and IL-10) cytokines, as well as IL-2 and IFNgamma by cord blood mononuclear cells (CBMC) of preterm newborns to that of peripheral blood mononuclear cells (PBMC) from adults.

METHODS

Mononuclear cells (MC) from individuals of the two age groups were incubated with vitamin A (retinyl palmitate) at various concentrations in the presence of phytohemagglutinin for IL-2 and IFNgamma production or LPS for IL-1beta, IL-1ra, IL-6 and IL-10 secretion. The level of the cytokines in the supernatants was tested by ELISA.

RESULTS

Vitamin A exerted an in vitro inhibitory effect on the production of the anti-inflammatory cytokine IL-1ra by MC of preterm newborns and adults, but did not affect the secretion of the pro-inflammatory cytokines IL-1beta, IL-6 and IFNgamma. Vitamin A caused inhibition of IL-10 secretion by cells from adults, but it did not significantly affect this function in cells from newborns except when high unphysiological doses were applied. In addition vitamin A stimulated the secretion of IL-2 by cells isolated from adults but had no effect on those derived from premature neonates.

CONCLUSIONS

The results indicate that vitamin A may affect the immune function of premature infants via inhibition of IL-1ra secretion. It is suggested that the beneficial effect of vitamin A on the clinical course of bronchopulmonary dysplasia (BPD) may be due to the reduced production of anti-inflammatory cytokines by neonatal CBMC. This may indicate the importance of the pro-inflammatory cytokines in the management of severe lung diseases and BPD.

Dexamethasone therapy and Candida sepsis in neonates less than 1250 grams

OBJECTIVE

To determine whether dexamethasone use increases the risk for Candida sepsis (CS) in very low birth weight premature infants (<1250 g).

DESIGN

Retrospective chart review of all infants with a birth weight <1250 g, admitted to the neonatal intensive care unit of the MetroHealth Medical Center, Cleveland, Ohio between January 1, 1996 and December 31, 1999. Infant groups with (n=65) and without (n=229) CS were compared.

RESULTS

Two hundred and ninety four infants with a birth weight <1250 g were identified. CS was diagnosed at a median age of 18 days, and 6 of 65 (10%) infants died directly from Candida-related complications. Candida albicans (n=30, 60%) and Candida parapsilosis (n=14, 25%) were the predominant isolates. Use of dexamethasone in infants at risk for chronic lung disease before 14 days of age (p=0.001), duration of antibiotics (p=0.001), and total duration of parenteral nutrition and intralipid (p=0.0001) were all significantly greater in infants who developed CS. Regression analysis showed that duration of antibiotics before the diagnosis of Candida infection (r(2)=0.69, p=0.0002) and duration of dexamethasone (r(2)=0.93, p=0.0002) correlated with Candida infection. Early dexamethasone use was also related to the age at diagnosis of Candida infection (r(2)=0.51, p=0.01).

CONCLUSIONS

Dexamethasone therapy and prolonged duration of antibiotics are associated with Candida infection in premature infants.

Effect of cefotaxime on cytokine production in newborns and adults in vitro

The in vitro effect of cefotaxime on the production of interleukin (IL)-1beta, IL-2, IL-6 and tumor necrosis factor alpha (TNFalpha) was studied in term neonates and was compared with that of adults. The addition of cefotaxime caused a significant enhancement of IL-2 production by cells of both adults and neonates, and increased the secretion of TNFalpha by peripheral blood mononuclear cells (PBMC) of adults, whereas the synthesis of this cytokine by cord blood mononuclear cells (CBMC) of the newborns was not affected. In contrast with the described stimulatory effects of cefotaxime, this drug induced dose-dependent inhibition of the spontaneous and lipopolysaccharide (LPS)-induced IL-1beta production by cells of the two groups, but had no effect on the in vitro production of IL-6. These data suggest that cefotaxime, apart from its known antimicrobial activity, may modify the host immune response of both newborns and adults, via the alteration of cytokine production.

Differential effects of glucocorticoids on colony stimulating factors produced by neonatal mononuclear cells

The purpose of this study was to examine the effect of dexamethasone (DEX) on the production of granulocyte and granulocyte-macrophage colony stimulating factors (G-CSF and GM-CSF) by neonatal mononuclear cells. Mononuclear cells were isolated from umbilical cord blood and cultured with either phorbol myristate acetate/phytohemagglutinin (PMA/PHA) or Candida albicans with or without DEX (10(-8)-10(-6) M) for 48 h. Cell supernatants were assayed for G-CSF and GM-CSF by ELISA. Mononuclear cells from term and preterm infants responded to PMA/PHA stimulation with a significant increase in G-CSF production over baseline levels. The PMA/PHA-induced increase in G-CSF production was markedly augmented by the addition of DEX to cell cultures. DEX augmented production of G-CSF was significantly less in mononuclear cells from preterm infants. Similarly, production of G-CSF was significantly less by mononuclear cells from infants with acute physiology scores of > or = 10, as judged by the Score for Acute Neonatal Physiology. In contrast, DEX significantly inhibited PMA/PHA-induced GM-CSF production. Although C. albicans induced mononuclear cells to produce G-CSF, DEX did not significantly augment this production. No significant effect of DEX on C. albicans induced GM-CSF production was observed. The data show DEX induced differential regulation of infant peripheral blood mononuclear cell production of G-CSF and GM-CSF. These results suggest that glucocorticoids may enhance certain aspects of host immune function in addition to their well-documented immunosuppressive effects. Further, the neutrophilia observed in DEX-treated infants may be due to enhanced G-CSF production.

G-CSF, GM-CSF and IL-6 levels in cord blood: diminished increase of G-CSF and IL-6 in preterms with perinatal infection compared to term neonates

AIM

The objectives of this study were 1) to clarify the physiologic regulation of cytokines such as IL-6, G-CSF and GM-CSF in preterm and term neonates and 2) to evaluate the influence of perinatal stress and infection on endogenous cytokine levels.

METHOD

We examined cord blood levels of G-CSF, GM-CSF and IL-6 using a bioassay in 43 term and 44 preterm neonates.

RESULTS

Compared to normal neonates (G-CSF: mean (m) = 97.6 +/- 16.3 pg/ml; IL-6: m = 20.2 +/- 4.6 pg/ml), we found elevated G-CSF levels in newborns with perinatal stress (m = 247.1 +/- 72.1 pg/ml; p = 0.003) and increased levels for G-CSF (m = 8980.9 +/- 4388 pg/ml; p = 0.0003) and IL-6 (m = 705 +/- 322.3 pg/ml; p = 0.025) in neonates with infection. Term newborns with infection had higher G-CSF levels than preterms (m = 15575 +/- 9374 pg/ml versus m = 5384.1 +/- 4470.9 pg/ml; p = 0.024). G-CSF levels of newborns with infection were correlated with birth weight (r = 0.50; p = 0.024) but not with gestational age (r = 0.40; p = 0.057). GM-CSF was only detectable in cord blood in 4 cases of normal healthy neonates.

CONCLUSIONS

The response of G-CSF levels in preterms to infection is diminished. Body cell mass is more important than gestational age to provide high G-CSF levels during states of infection.