Dorota Ferens

Effects of maternal tobacco smoking, sleeping position, and sleep state on arousal in healthy term infants

Objectives: To investigate whether a history of maternal tobacco smoking affected the maturation of arousal responses and whether sleeping position and infant age alters these relations. Design: Healthy term infants (13 born to mothers who did not smoke and 11 to mothers who smoked during pregnancy) were studied using daytime polysomnography on three occasions: (a) two to three weeks after birth, (b) two to three months after birth, and (c) five to six months after birth. Multiple measurements of arousal threshold in response to air jet stimulation were made in both active sleep (AS) and quiet sleep (QS) when infants slept both prone and supine. Results: Maternal smoking significantly elevated arousal threshold in QS when infants slept supine at 2–3 months of age (p<0.05). Infants of smoking mothers also had fewer spontaneous arousals from QS at 2–3 months in both prone (p<0.05) and supine (p<0.001) sleeping positions. In infants of non-smoking mothers, arousal thresholds were elevated in the prone position in AS at 2–3 months (p<0.01) and QS at 2–3 weeks (p<0.05) and 2–3 months (p<0.001). Conclusions: Maternal tobacco smoking significantly impairs both stimulus induced and spontaneous arousal from QS when infants sleep in the supine position, at the age when the incidence of sudden infant death syndrome is highest.

Obligatory Role for B Cells in the Development of Angiotensin II–Dependent Hypertension

Clinical hypertension is associated with raised serum IgG antibodies. However, whether antibodies are causative agents in hypertension remains unknown. We investigated whether hypertension in mice is associated with B-cell activation and IgG production and moreover whether B-cell/IgG deficiency affords protection against hypertension and vascular remodeling. Angiotensin II (Ang II) infusion (0.7 mg/kg per day; 28 days) was associated with (1) a 25% increase in the proportion of splenic B cells expressing the activation marker CD86, (2) an 80% increase in splenic plasma cell numbers, (3) a 500% increase in circulating IgG, and (4) marked IgG accumulation in the aortic adventitia. In B-cell–activating factor receptor–deficient (BAFF-R−/−) mice, which lack mature B cells, there was no evidence of Ang II–induced increases in serum IgG. Furthermore, the hypertensive response to Ang II was attenuated in BAFF-R−/− (&Dgr;30±4 mm Hg) relative to wild-type (&Dgr;41±5 mm Hg) mice, and this response was rescued by B-cell transfer. BAFF-R−/− mice displayed reduced IgG accumulation in the aorta, which was associated with 80% fewer aortic macrophages and a 70% reduction in transforming growth factor-&bgr; expression. BAFF-R−/− mice were also protected from Ang II–induced collagen deposition and aortic stiffening (assessed by pulse wave velocity analysis). Finally, like BAFF-R deficiency, pharmacological depletion of B cells with an anti-CD20 antibody attenuated Ang II–induced hypertension by ≈35%. Hence, these studies demonstrate that B cells/IgGs are crucial for the development of Ang II–induced hypertension and vessel remodeling in mice. Thus, B-cell–targeted therapies—currently used for autoimmune diseases—may hold promise as future treatments for hypertension.

Inflammasome activity is essential for one kidney/deoxycorticosterone acetate/salt-induced hypertension in mice

Inflammasomes are multimeric complexes that facilitate caspase‐1‐mediated processing of the pro‐inflammatory cytokines IL‐1β and IL‐18. Clinical hypertension is associated with renal inflammation and elevated circulating levels of IL‐1β and IL‐18. Therefore, we investigated whether hypertension in mice is associated with increased expression and/or activation of the inflammasome in the kidney, and if inhibition of inflammasome activity reduces BP, markers of renal inflammation and fibrosis.

Arousal responses and risk factors for sudden infant death syndrome

BACKGROUNDnFailure to arouse from sleep has been postulated as a mechanism to explain the final pathway of sudden infant death syndrome (SIDS).nnnMETHODSnWe have reviewed the effects of the major risk factors for SIDS, prone sleep position, maternal smoking, prematurity and recent infection on arousability from sleep. In human infants it has been consistently demonstrated that arousal from sleep in response to a variety of stimuli is more difficult to induce from quiet sleep (QS) compared to active sleep (AS) over the first 6 months of life.nnnRESULTSnIn the prone position both stimulus-induced and spontaneous arousability from both QS and AS were impaired at 2-3 weeks and 2-3 months, but not at 5-6 months of age in both term and preterm infants. In term infants exposed to maternal smoking during pregnancy both stimulus-induced and spontaneous arousability were impaired when infants slept supine in QS at 2-3 months of age. Healthy preterm infants showed no impairment in arousability compared with term infants at matched postconceptional ages. However, preterm infants with a history of apnoea and bradycardia of prematurity showed decreased arousal responses in both QS and AS and this impairment was positively correlated to their perinatal risk score. Infants who had recently suffered an infection requiring hospitalization showed decreased arousability in QS on the day of discharge when compared to 2 weeks later when they were completely well.nnnCONCLUSIONSnIn summary it has been found that the major risk factors for SIDS identified from epidemiological studies also decrease arousability from sleep in infants. We propose that this decreased arousability from sleep may be involved in the final pathway of SIDS.

Advanced atherosclerosis is associated with inflammation, vascular dysfunction and oxidative stress, but not hypertension

ABSTRACT Although hypertension may involve underlying inflammation, it is unknown whether advanced atherosclerosis − a chronic inflammatory condition − can by itself promote hypertension. We thus tested if advanced atherosclerosis in chronically hypercholesterolemic mice is associated with systemic and end‐organ inflammation, vascular dysfunction and oxidative stress, and whether blood pressure is higher than in control mice. Male ApoE−/− and wild‐type (C57Bl6J) mice were placed on a high fat or chow diet, respectively, from 5 to 61 weeks of age. Expression of several cytokines (including IL‐6, TNF‐&agr;, IFN‐&ggr; and/or IL‐1&bgr;) was elevated in plasma, brain, and aorta of ApoE−/− mice. Aortic superoxide production was ˜3.5‐fold greater, and endothelium‐dependent relaxation was markedly reduced in aorta and mesenteric artery of ApoE−/− versus wild‐type mice. There was no difference in blood pressure of aged ApoE−/− (104 ± 3 mmHg, n = 13) and wild‐type mice (113 ± 1 mmHg, n = 18). To clarify any effects of aging alone, findings from 61 week‐old wild‐type mice were compared with those from young (8–12 weeks old) chow‐fed wild‐type mice. The data indicate that aging alone increased renal and aortic expression of numerous cytokines (including CCL2, CCL7 and IL‐1&bgr;). Aging had no effect on blood pressure, systemic inflammation, oxidative stress or endothelial function. Despite systemic and end‐organ inflammation, oxidative stress and endothelial dysfunction, advanced atherosclerosis does not necessarily result in elevated blood pressure.

Anakinra reduces blood pressure and renal fibrosis in one kidney/DOCA/salt-induced hypertension

Objective: To determine whether a clinically‐utilised IL‐1 receptor antagonist, anakinra, reduces renal inflammation, structural damage and blood pressure (BP) in mice with established hypertension. Methods: Hypertension was induced in male mice by uninephrectomy, deoxycorticosterone acetate (2.4 mg/d, s.c.) and replacement of drinking water with saline (1K/DOCA/salt). Control mice received uninephrectomy, a placebo pellet and normal drinking water. 10 days post‐surgery, mice commenced treatment with anakinra (75 mg/kg/d, i.p.) or vehicle (0.9% saline, i.p.) for 11 days. Systolic BP was measured by tail cuff while qPCR, immunohistochemistry and flow cytometry were used to measure inflammatory markers, collagen and immune cell infiltration in the kidneys. Results: By 10 days post‐surgery, 1K/DOCA/salt‐treated mice displayed elevated systolic BP (148.3 ± 2.4 mmHg) compared to control mice (121.7 ± 2.7 mmHg; n = 18, P < 0.0001). The intervention with anakinra reduced BP in 1K/DOCA/salt‐treated mice by ˜20 mmHg (n = 16, P < 0.05), but had no effect in controls. In 1K/DOCA/salt‐treated mice, anakinra modestly reduced (˜30%) renal expression of some (CCL5, CCL2; n = 7–8; P < 0.05) but not all (ICAM‐1, IL‐6) inflammatory markers, and had no effect on immune cell infiltration (n = 7–8, P > 0.05). Anakinra reduced renal collagen content (n = 6, P < 0.01) but paradoxically appeared to exacerbate the renal and glomerular hypertrophy (n = 8–9, P < 0.001) that accompanied 1K/DOCA/salt‐induced hypertension. Conclusion: Despite its anti‐hypertensive and renal anti‐fibrotic actions, anakinra had minimal effects on inflammation and leukocyte infiltration in mice with 1K/DOCA/salt‐induced hypertension. Future studies will assess whether the anti‐hypertensive actions of anakinra are mediated by protective actions in other BP‐regulating or salt‐handling organs such as the arteries, skin and brain.

Temperament ratings do not predict arousability in normal infants and infants at increased risk of sudden infant death syndrome.

ABSTRACT. This study sought to determine whether temperament was an indicator of arousability from sleep in infants. We hypothesized that the “threshold” dimension would be the most predictive characteristic because it measures the stimulus intensity required to evoke a discernible response. Healthy term, healthy preterm, and preterm infants with a neonatal history of apnea underwent polysomnography at 2 to 3 months. Arousal was induced using air-jet stimulation of the nostrils in active (AS) and quiet sleep (QS). Temperament was assessed using the Early Infancy Temperament Questionnaire. Arousal thresholds were elevated in QS compared with AS in each group (p < .001), and preterm infants with a neonatal history of apnea were less arousable than healthy preterm infants (p < .05). Temperament was not a predictor of arousability in AS. “Adaptability” was the only significant predictor of arousability in QS. This study demonstrates that temperament characteristics as measured by questionnaire may not be reliable indicators of arousability from sleep.

Pharmacological inhibition of the NLRP3 inflammasome reduces blood pressure, renal damage and dysfunction in salt-sensitive hypertension

Abstract Aims Renal inflammation, leading to fibrosis and impaired function is a major contributor to the development of hypertension. The NLRP3 inflammasome mediates inflammation in several chronic diseases by processing the cytokines pro-interleukin (IL)-1β and pro-IL-18. In this study, we investigated whether MCC950, a recently-identified inhibitor of NLRP3 activity, reduces blood pressure (BP), renal inflammation, fibrosis and dysfunction in mice with established hypertension. Methods and results C57BL6/J mice were made hypertensive by uninephrectomy and treatment with deoxycorticosterone acetate (2.4u2009mg/day, s.c.) and 0.9% NaCl in the drinking water (1K/DOCA/salt). Normotensive controls were uninephrectomized and received normal drinking water. Ten days later, mice were treated with MCC950 (10u2009mg/kg/day, s.c.) or vehicle (saline, s.c.) for up to 25u2009days. BP was monitored by tail-cuff or radiotelemetry; renal function by biochemical analysis of 24-h urine collections; and kidney inflammation/pathology was assessed by real-time PCR for inflammatory gene expression, flow cytometry for leucocyte influx, and Picrosirius red histology for collagen. Over the 10u2009days post-surgery, 1K/DOCA/salt-treated mice became hypertensive, developed impaired renal function, and displayed elevated renal levels of inflammatory markers, collagen and immune cells. MCC950 treatment from day 10 attenuated 1K/DOCA/salt-induced increases in renal expression of inflammasome subunits (NLRP3, ASC, pro-caspase-1) and inflammatory/injury markers (pro-IL-18, pro-IL-1β, IL-17A, TNF-α, osteopontin, ICAM-1, VCAM-1, CCL2, vimentin), each by 25–40%. MCC950 reduced interstitial collagen and accumulation of certain leucocyte subsets in kidneys of 1K/DOCA/salt-treated mice, including CD206+ (M2-like) macrophages and interferon-gamma-producing T cells. Finally, MCC950 partially reversed 1K/DOCA/salt-induced elevations in BP, urine output, osmolality, [Na+], and albuminuria (each by 20–25%). None of the above parameters were altered by MCC950 in normotensive mice. Conclusion MCC950 was effective at reducing BP and limiting renal inflammation, fibrosis and dysfunction in mice with established hypertension. This study provides proof-of-concept that pharmacological inhibition of the NLRP3 inflammasome is a viable anti-hypertensive strategy.