Regulatory T cell proportion and phenotype are altered in women using oral contraception

Advance access publication 04 July 2022Regulatory T (Treg) cells are a specialized CD4+ T cell subpopulation that are essential for immune homeostasis, immune tolerance, and protection against autoimmunity. There is evidence that sex-steroid hormones estrogen and progesterone modulate Treg cell abundance and phenotype in women. Since natural oscillations in these hormones are modified by hormonal contraceptives, we examined whether oral contraception (OC) use impacts Treg cells and related T cell populations. T cells were analyzed by multiparameter flow cytometry in peripheral blood collected across the menstrual cycle from healthy women either using OC or without hormonal contraception and from age-matched men. Compared to naturally cycling women, women using OC had fewer Treg cells and an altered Treg cell phenotype. Notably, Treg cells exhibiting a strongly suppressive phenotype, defined by high FOXP3, CD25, Helios, HLADR, CTLA4, and Ki67, comprised a lower proportion of total Treg cells, particularly in the early- and mid-cycle phases. The changes were moderate compared to more substantial differences in Treg cells between women and men, wherein women had fewer Treg cells—especially of the effector memory Treg cell subset—associated with more T helper type 1 (Th1) cells and CD8+ T cells and lower Treg:Th1 cell and Treg:CD8+ T cell ratios than men. These findings imply that OC can modulate the number and phenotype of peripheral blood Treg cells and raise the possibility that Treg cells contribute to the physiological changes and altered disease susceptibility linked with OC use.Lachlan M. Moldenhauer, Min Jin, Jasmine J. Wilson, Ella S. Green, David J. Sharkey, Mark D. Salkeld, Thomas C. Bristow, M. Louise Hull, Gustaaf A. Dekker, and Sarah A. Robertso

Influence of biota on spatial and temporal variation in sediment erodability and material flux on a tidal flat (Westerschelde, The Netherlands)

Annular flumes were used to quantify benthic-pelaqic exchanges in relation to changes in current velocity and sediment biota. Various physical, chemical and biological parameters were determined for 4 sites on the Molenplaat tidal flat in the Westerschelde (The Netherlands) during 2 field campaigns in May-June and August-September 1996. These Pcluded: the mass of sediment eroded, maximum and mean erosion rates, critical erosion velocity (Ucrit), suspension feeding/biodeposition rate, oxygen and ammonium fluxes, density of macrofauna species, chlorophyll a (chl-a), colloidal carbohydrate, and physical properties of the sediment. The study showed marked and statistically significant spatial and temporal differences in the potential for sediment erosion. Sites in the centre of the tidal flat were less erodable than those on the edge. All sites on the tidal flat had a significantly (p &lt; 0.001) lower erosion potential in June (i.e. higher Ucrit and lower erosion rates) compared to September. The presence of a well-developed microphytobenthos community in June resulted in a statistically significant relationship between Ucrit and chl-a/colloidal carbohydrate (r = +0.85, p = 0.01). There was a significant relationship (r = +0.88, p = 0.005) between sediment erodability (mass of sediment eroded and erosion rate) and the density of the clam Macoma balthica, a major bioturbator of the surface sediments. Analysis of the data also demonstrated significant relationships between clearance rate and Cerastoderma edule biomass (r = +0.91, p &lt; 0.001), and between sedment chl-a/colloidal carbohydrate and C. edule biomass (r = +0.92; p &lt; 0.001), reflecting the influence of suspension feeders on both the water column and the sediment, through their biodeposits. The significant increase in sediment erodability between June and September reflected the shift in the overall balance between the major 'biostabilisers' (microphytobenthos) and 'bio-destabilisers' (bioturbating bivalves). Ths interpretation of field-derived correlations is consistent with previously established relationships and mechanistic understanding derived from controlled flume experiments.<br/

Benthic-pelagic exchange of microalgae at a tidal flat. 1. Pigment analysis

Annular flume experiments and high-performance liquid chromatography (HPLC) were used to quantitatively and qualitatively measure benthic-pelagic exchange of microphytobenthos from natural sediments. Clear spatial and temporal differences in. microphytobenthos resuspension in response to stepwise increases in current velocity were observed. Resuspension of chlorophyll a (chl a) from sandy sediments containing low levels of microphytobenthos biomass (56 mg chl a m(- 2)) displayed strong resistance to erosion at current

Benthic-pelagic exchange of microalgae at a tidal flat: 1. Pigment analysis

Annular flume experiments and high-performance liquid chromatography (HPLC) were used to quantitatively and qualitatively measure benthic-pelagic exchange of microphytobenthos from natural sediments. Clear spatial and temporal differences in microphytobenthos resuspension in response to stepwise increases in current velocity were observed. Resuspension of chlorophyll a (chl a) from sandy sediments containing low levels of microphytobenthos biomass (&lt;11.5 mg chl a m-2) occurred gradually and continuously over a range of current velocities from 10 to 40 cm s-1. In June, well-developed diatom mats at siltier sites (&gt;56 mg chl a m-2) displayed strong resistance to erosion at currents &lt;20 to 25 cm s-1, above which there was a very rapid increase in the amount of chl a in suspension following the stripping of the algal mat from the sediment surface. In September, when the diatom bloom was over, these sediments were less resistant to erosion and resuspension of microalgae occurred at current velocities above 15 to 20 cm-1. Site 1, situated at the edge of the flat, had a dense algal mat but low sediment stability. Microalgae were readily resuspended because the extracellular polymeric substances (EPS) produced by the migratory diatoms were unable to consolidate during the short emersion period. As a rule more chl a was resuspended from sandy sediments at current velocities 15 and 20 cm-1, but above this current velocity chl a resuspension was greater from silty sediments. Although sandy sites have low biomass in the surface layer, the greater depth of sediment erosion during bedload transport exposes more chl a to the surface. The percentage of sedimentary chl a lost at selected current velocities was estimated, and the implications for carbon supply to the pelagic and benthic systems discussed. Much of the biomass resuspended may be deposited locally, particularly in sandier regions. During the flume experiments it was observed that settling of fine sediment and microalgae was extremely rapid, because it was being biodeposited by suspension-feeding activity, and 'stripped' out of the water column by rapidly sinking suspended particulate matter (SPM). Qualitative changes in suspended material were measured as % chl a (chl a/phaeopigments ¥ 100%) and accessory pigment content. As current velocity increased the relative proportion of phaeopigments increased, which has important implications for benthic suspension feeders feeding in the benthic boundary layer. The findings from the flume experiments have been compared with in situ measurements of current velocity, SPM and chl a