Purinergic signalling links mechanical breath profile and alveolar mechanics with the pro-inflammatory innate immune response causing ventilation-induced lung injury

Severe pulmonary infection or vigorous cyclic deformation of the alveolar epithelial type I (AT I) cells by mechanical ventilation leads to massive extracellular ATP release. High levels of extracellular ATP saturate the ATP hydrolysis enzymes CD39 and CD73 resulting in persistent high ATP levels despite the conversion to adenosine. Above a certain level, extracellular ATP molecules act as danger-associated molecular patterns (DAMPs) and activate the pro-inflammatory response of the innate immunity through purinergic receptors on the surface of the immune cells. This results in lung tissue inflammation, capillary leakage, interstitial and alveolar oedema and lung injury reducing the production of surfactant by the damaged AT II cells and deactivating the surfactant function by the concomitant extravasated serum proteins through capillary leakage followed by a substantial increase in alveolar surface tension and alveolar collapse. The resulting inhomogeneous ventilation of the lungs is an important mechanism in the development of ventilation-induced lung injury. The high levels of extracellular ATP and the upregulation of ecto-enzymes and soluble enzymes that hydrolyse ATP to adenosine (CD39 and CD73) increase the extracellular adenosine levels that inhibit the innate and adaptive immune responses rendering the host susceptible to infection by invading microorganisms. Moreover, high levels of extracellular adenosine increase the expression, the production and the activation of pro-fibrotic proteins (such as TGF-β, α-SMA, etc.) followed by the establishment of lung fibrosis

Does chronic stress enhance the risk of diseases?

In the everyday life, stress is deemed as something unfavorable that may enhance the risk for the development or worsen a disease. However, in its nature, stress is adaptive reaction of the body. Its main characteristic is the activation of the hypothalamic-pituitary-adrenocortical (HPA) axis. Previously, we have shown that activation of the HPA axis plays a gastroprotective role during acute stress. The aim of our study was to clarify the effects of chronic stress and chronically elevated basal corticosterone levels on the gastric ulceration and cardiovascular vulnerability in rats.Methods. Male Wistar rats were repeatedly restrained 60 min daily for 14 days and examined on day 15th. The gastric ulceration was induced by a s.c. injection of indomethacin (35 mg/kg). The cardiovascular vulnerability was examined in urethane-anaesthetized rats in an experimental angina pectoris model (epinephrine, 10 microg/kg, 30 s later phentolamine, 15 mg/kg, both i.v.).Results. We confirmed the development of chronic stress consequences by changes in several somatic parameters (body weight decrease, thymus involution, adrenal gland hypertrophy), and elevated resting corticosterone levels. However, the gastroprotective effect of chronic stress was not manifested and there was no aggravation of indomethacin-induced gastric ulceration, either. In the experimental angina pectoris model, previous chronic stress did not have any profound effect on the blood pressure, heart rate, and electrocardiogram changes.Conclusions. In contrast to the general view on the harmfulness nature of the stress, we were unable to find a harmful effect of chronic stress on the internal diseases (gastric ulceration and angina pectoris). However, its protective effect was also missing among present experimental conditions. Keywords: chronic stress, indomethacin-induced gastric ulceration, experimental angina pectoris

Role of astroglia and insulin-like growth factor-I in gonadal hormone- dependent synaptic plasticity

Gonadal hormones exert a critical influence over the architecture of specific brain areas affecting the formation of neuronal contacts. Cellular mechanisms mediating gonadal hormone actions on synapses have been studied extensively in the rat arcuate nucleus, a hypothalamic center involved in the feed-back regulation of gonadotropins. Gonadal steroids exert organizational and activational effects on arcuate nucleus synaptic connectivity. Perinatal testosterone induces a sexual dimorphic pattern of synaptic contacts. Furthermore, during the preovulatory and ovulatory phases of the estrous cycle there is a transient disconnection of inhibitory synaptic inputs to the somas of arcuate neurons. This synaptic remodeling is induced by estradiol, blocked by progesterone, and begins with the onset of puberty in females. Astroglia appear to play a significant role in the organizational and the activational hormone effects on neuronal connectivity by regulating the amount of neuronal membrane available for the formation of synaptic contacts and by releasing soluble factors, such as insulin-like growth factor I (IGF- I), which promote the differentiation of neural processes. Recent evidence indicates that gonadal steroids and IGF-I may interact in their trophic effects on the neuroendocrine hypothalamus. Estradiol and IGF-I promote the survival and morphological differentiation of rat hypothalamic neurons in primary cultures. The effect of estradiol depends on IGF-I, while the effects of both estradiol and IGF-I depend on estrogen receptors. Furthermore, estrogen activation of astroglia in hypothalamic tissue fragments depends on IGF-I receptors. These findings indicate that IGF-I may mediate some of the developmental and activational effects of gonadal steroids on the brain and suggest that IGF-I may activate the estrogen receptor to induce its neurotrophic effects on hypothalamic cells. In addition, IGF-I levels in the neuroendocrine hypothalamus are regulated by gonadal steroids. IGF-I levels in tanycytes, a specific astroglia cell type present in the arcuate nucleus and median eminence, increase at puberty, are affected by neonatal androgen levels, show sex differences, and fluctuate in accordance to the natural variations in plasma levels of ovarian steroids that are associated with the estrous cycle. These changes appear to be mediated by hormonal regulation of IGF-I uptake from blood or cerebrospinal fluid by tanycytes. These results suggest that tanycytes may be involved in the regulation of neuroendocrine events in adult rats by regulating the availability of IGF-I to hypothalamic neurons. In summary, IGF-I and different forms of neuron-astroglia communication are involved in the effects of estradiol on synaptic plasticity in the hypothalamic arcuate nucleus.Peer Reviewe

Two-Dimensional Regulation of CAR-T Cell Therapy with Orthogonal Switches

Use of chimeric antigen receptors (CARs) as the basis of targeted adoptive T cell therapies has enabled dramatic efficacy against multiple hematopoietic malignancies, but potency against bulky and solid tumors has lagged, potentially due to insufficient CAR-T cell expansion and persistence. To improve CAR-T cell efficacy, we utilized a potent activation switch based on rimiducid-inducible MyD88 and CD40 (iMC)-signaling elements. To offset potential toxicity risks by this enhanced CAR, an orthogonally regulated, rapamycin-induced, caspase-9-based safety switch (iRC9) was developed to allow in vivo elimination of CAR-T cells. iMC costimulation induced by systemic rimiducid administration enhanced CAR-T cell proliferation, cytokine secretion, and antitumor efficacy in both in vitro assays and xenograft tumor models. Conversely, rapamycin-mediated iRC9 dimerization rapidly induced apoptosis in a dose-dependent fashion as an approach to mitigate therapy-related toxicity. This novel, regulatable dual-switch system may promote greater CAR-T cell expansion and prolonged persistence in a drug-dependent manner while providing a safety switch to mitigate toxicity concerns. Keywords: CAR-T, dimerizer, cell therapy, costimulation switch, apoptosis, rapamycin, rimiducid, iMC, iRC9, safety switc

Attenuation of Chronic Pulmonary Inflammation in A2B Adenosine Receptor Knockout Mice

Pharmacologic evidence suggests that activation of A2B adenosine receptors results in proinflammatory effects relevant to the progression of asthma, a chronic lung disease associated with elevated interstitial adenosine concentrations in the lung. This concept has been challenged by the finding that genetic removal of A2B receptors leads to exaggerated responses in models of acute inflammation. Therefore, the goal of our study was to determine the effects of A2B receptor gene ablation in the context of ovalbumin-induced chronic pulmonary inflammation. We found that repetitive airway allergen challenge induced a significant increase in adenosine levels in fluid recovered by bronchoalveolar lavage. Genetic ablation of A2B receptors significantly attenuated allergen-induced chronic pulmonary inflammation, as evidenced by a reduction in the number of bronchoalveolar lavage eosinophils and in peribronchial eosinophilic infiltration. The most striking difference in the pulmonary inflammation induced in A2B receptor knockout (A2BKO) and wild-type mice was the lack of allergen-induced IL-4 release in the airways of A2BKO animals, in line with a significant reduction in IL-4 protein and mRNA levels in lung tissue. In addition, attenuation of allergen-induced transforming growth factor–β release in airways of A2BKO mice correlated with reduced airway smooth muscle and goblet cell hyperplasia/hypertrophy. In conclusion, genetic removal of A2B adenosine receptors in mice leads to inhibition of allergen-induced chronic pulmonary inflammation and airway remodeling. These findings are in agreement with previous pharmacologic studies suggesting a deleterious role for A2B receptor signaling in chronic lung inflammation