feedback loop
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Author(s):  
Tao Yang ◽  
Zhengdong Deng ◽  
Lei Xu ◽  
Xiangyu Li ◽  
Tan Yang ◽  
...  

Abstract Background Recent data indicated that macrophages may mutually interact with cancer cells to promote tumor progression and chemoresistance, but the interaction in cholangiocarcinoma (CCA) is obscure. Methods 10x Genomics single-cell sequencing technology was used to identified the role of macrophages in CCA. Then, we measured the expression and prognostic role of macrophage markers and aPKCɩ in 70 human CCA tissues. Moreover, we constructed monocyte-derived macrophages (MDMs) generated from peripheral blood monocytes (PBMCs) and polarized them into M1/M2 macrophages. A co-culture assay of the human CCA cell lines (TFK-1, EGI-1) and differentiated PBMCs-macrophages was established, and functional studies in vitro and in vivo was performed to explore the interaction between cancer cells and M2 macrophages. Furthermore, we established the cationic liposome-mediated co-delivery of gemcitabine and aPKCɩ-siRNA and detect the antitumor effects in CCA. Results M2 macrophage showed tumor-promoting properties in CCA. High levels of aPKCɩ expression and M2 macrophage infiltration were associated with metastasis and poor prognosis in CCA patients. Moreover, CCA patients with low M2 macrophages infiltration or low aPKCɩ expression benefited from postoperative gemcitabine-based chemotherapy. Further studies showed that M2 macrophages-derived TGFβ1 induced epithelial-mesenchymal transition (EMT) and gemcitabine resistance in CCA cells through aPKCɩ-mediated NF-κB signaling pathway. Reciprocally, CCL5 was secreted more by CCA cells undergoing aPKCɩ-induced EMT and consequently modulated macrophage recruitment and polarization. Furthermore, the cationic liposome-mediated co-delivery of GEM and aPKCɩ-siRNA significantly inhibited macrophages infiltration and CCA progression. Conclusion our study demonstrates the role of Macrophages-aPKCɩ-CCL5 Feedback Loop in CCA, and proposes a novel therapeutic strategy of aPKCɩ-siRNA and GEM co-delivered by liposomes for CCA.


2022 ◽  
Vol 23 (2) ◽  
pp. 867
Author(s):  
Sebastian F. Mause ◽  
Elisabeth Ritzel ◽  
Annika Deck ◽  
Felix Vogt ◽  
Elisa A. Liehn

Endothelial progenitor cells (EPCs) are involved in vascular repair and modulate properties of smooth muscle cells (SMCs) relevant for their contribution to neointima formation following injury. Considering the relevant role of the CXCL12–CXCR4 axis in vascular homeostasis and the potential of EPCs and SMCs to release CXCL12 and express CXCR4, we analyzed the engagement of the CXCL12–CXCR4 axis in various modes of EPC–SMC interaction relevant for injury- and lipid-induced atherosclerosis. We now demonstrate that the expression and release of CXCL12 is synergistically increased in a CXCR4-dependent mechanism following EPC–SMC interaction during co-cultivation or in response to recombinant CXCL12, thus establishing an amplifying feedback loop Additionally, mechanical injury of SMCs induces increased release of CXCL12, resulting in enhanced CXCR4-dependent recruitment of EPCs to SMCs. The CXCL12–CXCR4 axis is crucially engaged in the EPC-triggered augmentation of SMC migration and the attenuation of SMC apoptosis but not in the EPC-mediated increase in SMC proliferation. Compared to EPCs alone, the alliance of EPC–SMC is superior in promoting the CXCR4-dependent proliferation and migration of endothelial cells. When direct cell–cell contact is established, EPCs protect the contractile phenotype of SMCs via CXCL12–CXCR4 and reverse cholesterol-induced transdifferentiation toward a synthetic, macrophage-like phenotype. In conclusion we show that the interaction of EPCs and SMCs unleashes a CXCL12–CXCR4-based autoregulatory feedback loop promoting regenerative processes and mediating SMC phenotype control to potentially guard vascular homeostasis.


2022 ◽  
Vol 9 ◽  
Author(s):  
Lijin Xiang ◽  
Shiqun Ma ◽  
Lu Yu ◽  
Wenhao Wang ◽  
Zhichao Yin

The COVID-19 infections have profoundly and negatively impacted the whole world. Hence, we have modeled the dynamic spread of global COVID-19 infections with the connectedness approach based on the TVP-VAR model, using the data of confirmed COVID-19 cases during the period of March 23rd, 2020 to September 10th, 2021 in 18 countries. The results imply that, (i) the United States, the United Kingdom and Indonesia are global epidemic centers, among which the United States has the highest degree of the contagion of the COVID-19 infections, which is stable. South Korea, France and Italy are the main receiver of the contagion of the COVID-19 infections, and South Korea has been the most severely affected by the overseas epidemic; (ii) there is a negative correlation between the timeliness, effectiveness and mandatory nature of government policies and the risk of the associated countries COVID-19 epidemic affecting, as well as the magnitude of the net contagion of domestic COVID-19; (iii) the severity of domestic COVID-19 epidemics in the United States and Canada, Canada and Mexico, Indonesia and Canada is almost equivalent, especially for the United States, Canada and Mexico, whose domestic epidemics are with the same tendency; (iv) the COVID-19 epidemic has spread though not only the central divergence manner and chain mode of transmission, but also the way of feedback loop. Thus, more efforts should be made by the governments to enhance the pertinence and compulsion of their epidemic prevention policies and establish a systematic and efficient risk assessment mechanism for public health emergencies.


2022 ◽  
Vol 23 (2) ◽  
pp. 848
Author(s):  
Rodrigo P. Silva-Aguiar ◽  
Diogo B. Peruchetti ◽  
Lucas S. Florentino ◽  
Christina M. Takiya ◽  
María-Paz Marzolo ◽  
...  

Renal proximal tubule cells (PTECs) act as urine gatekeepers, constantly and efficiently avoiding urinary protein waste through receptor-mediated endocytosis. Despite its importance, little is known about how this process is modulated in physiologic conditions. Data suggest that the phosphoinositide-3-kinase (PI3K)/protein kinase B (AKT) pathway regulates PTEC protein reabsorption. Here, we worked on the hypothesis that the physiologic albumin concentration and PI3K/AKT pathway form a positive feedback loop to expand endocytic capacity. Using LLC-PK1 cells, a model of PTECs, we showed that the PI3K/AKT pathway is required for megalin recycling and surface expression, affecting albumin uptake. Inhibition of this pathway stalls megalin at EEA1+ endosomes. Physiologic albumin concentration (0.01 mg/mL) activated AKT; this depends on megalin-mediated albumin endocytosis and requires previous activation of PI3K/mTORC2. This effect is correlated to the increase in albumin endocytosis, a phenomenon that we refer to as “albumin-induced albumin endocytosis”. Mice treated with L-lysine present decreased albumin endocytosis leading to proteinuria and albuminuria associated with inhibition of AKT activity. Renal cortex explants obtained from control mice treated with MK-2206 decreased albumin uptake and promoted megalin internalization. Our data highlight the mechanism behind the capacity of PTECs to adapt albumin reabsorption to physiologic fluctuations in its filtration, avoiding urinary excretion.


Author(s):  
Aditya Singh ◽  
Manish Thakur ◽  
Akshat shah ◽  
Neerake Bajaj ◽  
Hardik Taneja ◽  
...  

Each and every automobile in service or being developed in the industry is benchmarked on the basis of its efficiency in running real conditions. So in our project here we have tried to develop a complete new damper and spring setup which can be used in all sorts of suspension systems and in turn provides a feedback loop of voltage which can then be used charge the batteries and upscale the efficiency of bikes by (5-6)% & and for HUV or Sedans by (2-4)% (can even go higher) depending on the terrain. In this setup we harness the mechanical energy into electrical where earlier it was left as heat and vibrational losses. This setup is as cost effective as the earlier dampers where as providing an efficient output in minimal cost increase due to its novelty. The other Features include Electronic height adjustment & on demand suspension softness or stiffness. Keywords: Dampers, Automobile, Electromagnet, EV (Electric vehicle), Voltage, Magnetic flux, Suspension


Author(s):  
Haijiao Jing ◽  
Nan Zuo ◽  
Valerie A. Novakovic ◽  
Jialan Shi

Cancer patients have increased SARS-CoV-2 susceptibility and are prone to developing severe COVID-19 infections. The incidence of venous thrombosis is approximately 20% in COVID-19 patients with cancer. It has been suggested that thrombus formation has been suggested to correlate with severe clinical manifestations, mortality, and sequelae. In this review, we primarily elaborate on the pathophysiological mechanisms of thrombosis in COVID-19 patients with cancer, emphasize the role of microparticles (MPs) and phosphatidylserine (PS) in coagulation, and propose an antithrombotic strategy. The coagulation mechanisms of COVID-19 and cancer synergistically amplify the coagulation cascade, and collectively promotes pulmonary microvascular occlusion. During systemic coagulation, the virus activates immune cells to release abundant proinflammatory cytokines, referred to as cytokine storm, resulting in the apoptosis of tumor and blood cells and subsequent MPs release. Additionally, we highlight that tumor cells contribute to MPs and coagulation by apoptosis owing to insufficient blood supply. A positive feedback loop of cytokines storm and MPs storm promotes microvascular coagulation storm, leading to microthrombi formation and inadequate blood perfusion. Microthrombi-damaged endothelial cells (ECs), tumor, and blood cells further aggravate the apoptosis of the cells and facilitate MPs storm. PS, especially on MPs, plays a pivotal role in the blood coagulation process, contributing to clot initiation, amplification, and propagation. Since coagulation is a common pathway of COVID-19 and cancer, and associated with mortality, patients would benefit from antithrombotic therapy. The above results lead us to assert that early stage antithrombotic therapy is optimal. This strategy is likely to maintain blood flow patency contributing to viral clearance, attenuating the formation of cytokines and MPs storm, maintaining oxygen saturation, and avoiding the progress of the disease.


2022 ◽  
Author(s):  
Uramogi Wang

Continuous persist activity of the competitive network is related to many functions, such as working memory, oculomotor integrator and decision making. Many competition models with mutual inhibition structures achieve activity maintenance via positive feedback, which requires meticulous fine tuning of the network parameters strictly. Negative derivative feedback, according to recent research, might represent a novel mechanism for sustaining neural activity that is more resistant to multiple neural perturbations than positive feedback. Many classic models with only mutual inhibition structure are not capable of providing negative derivative feedback because double-inhibition acts as a positive feedback loop, and lack of negative feedback loop that is indispensable for negative derivative feedback. Here in the proposal, we aim to derive a new competition network with negative derivative feedback. The network is made up of two symmetric pairs of EI populations that the four population are completely connected. We conclude that the negative derivative occurs in two circumstances, in which one the activity of the two sides is synchronous but push-pull-like in the other, as well as the switch of two conditions in mathematical analysis and numerical simulation.


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