Evaluating The Precocial-altricial Axis of Motor Skill at Birth in A Preterm Pig Model.

The pace of locomotor development is a critical component of lifetime evolutionary fitness. Developmental researchers often divide species into two broad categories based on functional competence at birth: precocial infants who can independently stand and locomote soon after birth versus altricial infants who are either incapable of independent movement or can only do so in a rudimentary manner. However, investigating the lower level neuromotor and biomechanical traits that account for perinatal variation in motor development is complicated by the lack of experimental control inherent to all comparative analyses. Precocial and altricial animals often differ along a host of dimensions that can obfuscate the specific factors controlling motor development per se. Here, we propose an alternative approach of examining locomotor development in a nominally precocial species-the domestic pig (Sus scrofa)-in which gestation length has been experimentally manipulated, thereby creating "functionally altricial" cohorts for comparison. We have used standard biomechanical testing to evaluate balance and locomotor performance in preterm pigs born at 94% full-term gestation (N = 29 individuals) and compared these data to a similar dataset on age-matched full-term piglets (N = 15 individuals). Static balance tests showed that preterm pigs were characterized by increased postural sway, particularly in the fore-aft (anteroposterior) direction. Locomotor analyses showed that preterm piglets tended to take shorter, more frequent strides, use higher duty factors, and preferentially choose gait patterns that ensured they were supported by at least three limbs during most of the stride cycle, though differences between preterm and full-term animals were often modulated by variation in locomotor speed. Morphometric analysis showed no differences in relative extensor muscle mass between preterm and full-term animals, suggesting that neurological immaturity might be more determinant of preterm piglet motor dysfunctions than musculoskeletal immaturity per se (though much work remains to be done to fully document the neuromotor phenotype of the preterm infant pig model). In many ways, the postural and locomotor deficits shown by the preterm piglets paralleled the locomotor phenotype of altricial mammals. Overall, our study demonstrates the utility of a "within-species" design for studying the biomechanical correlates and neuromotor basis of evolutionary variation in motor skill at birth.

Phosphodiesterase 4D contributes to angiotensin II-induced abdominal aortic aneurysm through smooth muscle cell apoptosis.

Abdominal aortic aneurysm (AAA) is a permanent expansion of the abdominal aorta that has a high mortality but limited treatment options. Phosphodiesterase (PDE) 4 family members are cAMP-specific hydrolyzing enzymes and have four isoforms (PDE4A-PDE4D). Several pan-PDE4 inhibitors are used clinically. However, the regulation and function of PDE4 in AAA remain largely unknown. Herein, we showed that PDE4D expression is upregulated in human and angiotensin II-induced mouse AAA tissues using RT-PCR, western blotting, and immunohistochemical staining. Furthermore, smooth muscle cell (SMC)-specific Pde4d knockout mice showed significantly reduced vascular destabilization and AAA development in an experimental AAA model. The PDE4 inhibitor rolipram also suppressed vascular pathogenesis and AAA formation in mice. In addition, PDE4D deficiency inhibited caspase 3 cleavage and SMC apoptosis in vivo and in vitro, as shown by bulk RNA-seq, western blotting, flow cytometry and TUNEL staining. Mechanistic studies revealed that PDE4D promotes apoptosis by suppressing the activation of cAMP-activated protein kinase A (PKA) instead of the exchange protein directly activated by cAMP (Epac). Additionally, the phosphorylation of BCL2-antagonist of cell death (Bad) was reversed by PDE4D siRNA in vitro, which indicates that PDE4D regulates SMC apoptosis via the cAMP-PKA-pBad axis. Overall, these findings indicate that PDE4D upregulation in SMCs plays a causative role in AAA development and suggest that pharmacological inhibition of PDE4 may represent a potential therapeutic strategy.

Inhibition of gasdermin D-dependent pyroptosis attenuates the progression of silica-induced pulmonary inflammation and fibrosis.

Silicosis is a leading cause of occupational disease-related morbidity and mortality worldwide, but the molecular basis underlying its development remains unclear. An accumulating body of evidence supports gasdermin D (GSDMD)-mediated pyroptosis as a key component in the development of various pulmonary diseases. However, there is little experimental evidence connecting silicosis and GSDMD-driven pyroptosis. In this work, we investigated the role of GSDMD-mediated pyroptosis in silicosis. Single-cell RNA sequencing of healthy and silicosis human and murine lung tissues indicated that GSDMD-induced pyroptosis in macrophages was relevant to silicosis progression. Through microscopy we then observed morphological alterations of pyroptosis in macrophages treated with silica. Measurement of interleukin-1ß release, lactic dehydrogenase activity, and real-time propidium iodide staining further revealed that silica induced pyroptosis of macrophages. Additionally, we verified that both canonical (caspase-1-mediated) and non-canonical (caspase-4/5/11-mediated) signaling pathways mediated silica-induced pyroptosis activation, in vivo and in vitro. Notably, Gsdmd knockout mice exhibited dramatically alleviated silicosis phenotypes, which highlighted the pivotal role of pyroptosis in this disease. Taken together, our results demonstrated that macrophages underwent GSDMD-dependent pyroptosis in silicosis and inhibition of this process could serve as a viable clinical strategy for mitigating silicosis.

Phosphodiesterase 4D promotes angiotensin II-induced hypertension in mice via smooth muscle cell contraction.

Hypertension is a common chronic disease, which leads to cardio-cerebrovascular diseases, and its prevalence is increasing. The cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) pathway participates in multiple cardiovascular diseases. Phosphodiesterase (PDE) 4 has been shown to regulate PKA activity via cAMP specific hydrolysis. However, whether PDE4-cAMP-PKA pathway influences hypertension remains unknown. Herein, we reveal that PDE4D (one of PDE4 isoforms) expression is upregulated in the aortas of experimental hypertension induced by angiotensin II (Ang II). Furthermore, knockout of Pde4d in mouse smooth muscle cells (SMCs) attenuates Ang II-induced hypertension, arterial wall media thickening, vascular fibrosis and vasocontraction. Additionally, we find that PDE4D deficiency activates PKA-AMP-activated protein kinase (AMPK) signaling pathway to inhibit myosin phosphatase targeting subunit 1 (MYPT1)-myosin light chain (MLC) phosphorylation, relieving Ang II-induced SMC contraction in vitro and in vivo. Our results also indicate that rolipram, a PDE4 inhibitor, may be a potential drug for hypertension therapy.

Tetrandrine alleviates silicosis by inhibiting canonical and non-canonical NLRP3 inflammasome activation in lung macrophages.

Silicosis caused by inhalation of silica particles leads to more than ten thousand new occupational exposure-related deaths yearly. Exacerbating this issue, there are currently few drugs reported to effectively treat silicosis. Tetrandrine is the only drug approved for silicosis treatment in China, and despite more than decades of use, its efficacy and mechanisms of action remain largely unknown. Here, in this study, we established silicosis mouse models to investigate the effectiveness of tetrandrine of early and late therapeutic administration. To this end, we used multiple cardiopulmonary function test, as well as markers for inflammation and fibrosis. Moreover, using single cell RNA sequencing and transcriptomics of lung tissue and quantitative microarray analysis of serum from silicosis and control mice, our results provide a novel description of the target pathways for tetrandrine. Specifically, we found that tetrandrine attenuated silicosis by inhibiting both the canonical and non-canonical NLRP3 inflammasome pathways in lung macrophages. Taken together, our work showed that tetrandrine yielded promising results against silicosis-associated inflammation and fibrosis and further lied the groundwork for understanding its molecular targets. Our results also facilitated the wider adoption and development of tetrandirne, potentially accelerating a globally accepted therapeutic strategy for silicosis.