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Reports of post-acute COVID-19 syndrome, in which the inflammatory response persists even after SARS-CoV-2 has disappeared, are increasing1, but the underlying mechanisms of post-acute COVID-19 syndrome remain unknown. Here, we show that SARS-CoV-2-infected cells trigger senescence-like cell-cycle arrest2,3 in neighboring uninfected cells in a paracrine manner via virus-induced cytokine production. In cultured human cells or bronchial organoids, these SASR-CoV-2 infection-induced senescent cells express high levels of a series of inflammatory factors known as senescence-associated secretory phenotypes (SASPs)4 in a sustained manner, even after SARS-CoV-2 is no longer detectable. We also show that the expression of the senescence marker CDKN2A (refs. 5,6) and various SASP factor4 genes is increased in the pulmonary cells of patients with severe post-acute COVID-19 syndrome. Furthermore, we find that mice exposed to a mouse-adapted strain of SARS-CoV-2 exhibit prolonged signs of cellular senescence and SASP in the lung at 14 days after infection when the virus was undetectable, which could be substantially reduced by the administration of senolytic drugs7. The sustained infection-induced paracrine senescence described here may be involved in the long-term inflammation caused by SARS-CoV-2 infection.

Although cellular senescence acts primarily as a tumour suppression mechanism, the accumulation of senescent cells in vivo eventually exerts deleterious side effects through inflammatory/tumour-promoting factor secretion. Thus, the development of new drugs that cause the specific elimination of senescent cells, termed senolysis, is anticipated. Here, by an unbiased high-throughput screening of chemical compounds and a bio-functional analysis, we identify BET family protein degrader (BETd) as a promising senolytic drug. BETd provokes senolysis through two independent but integrated pathways; the attenuation of non-homologous end joining (NHEJ), and the up-regulation of autophagic gene expression. BETd treatment eliminates senescent hepatic stellate cells in obese mouse livers, accompanied by the reduction of liver cancer development. Furthermore, the elimination of chemotherapy-induced senescent cells by BETd increases the efficacy of chemotherapy against xenograft tumours in immunocompromised mice. These results reveal the vulnerability of senescent cells and open up possibilities for its control., Senescent cells can influence the tumour microenvironment by secreting immunomodulatory factors and are thus a therapeutic target. Here, the authors identify a compound that degrades BET leading to DNA damage and activation of autophagy and a reduction in tumour growth.

Emerging evidence is revealing that alterations in gut microbiota are associated with colorectal cancer (CRC). However, very little is currently known about whether and how gut microbiota alterations are causally associated with CRC development. Here we show that 12 faecal bacterial taxa are enriched in CRC patients in two independent cohort studies. Among them, 2 Porphyromonas species are capable of inducing cellular senescence, an oncogenic stress response, through the secretion of the bacterial metabolite, butyrate. Notably, the invasion of these bacteria is observed in the CRC tissues, coinciding with the elevation of butyrate levels and signs of senescence-associated inflammatory phenotypes. Moreover, although the administration of these bacteria into ApcΔ14/+ mice accelerate the onset of colorectal tumours, this is not the case when bacterial butyrate-synthesis genes are disrupted. These results suggest a causal relationship between Porphyromonas species overgrowth and colorectal tumourigenesis which may be due to butyrate-induced senescence., Several bacteria in the gut microbiota have been associated with colorectal cancer (CRC) but it is not completely clear whether they have a role in tumourigenesis. Here, the authors show enrichment of 12 bacterial taxa in two cohorts of CRC patients and that two Porphyromonas species accelerate CRC onset through butyrate secretion.

Accumulating evidence indicates that the senescence-associated secretory phenotype (SASP) contributes to many aspects of physiology and disease. Thus, controlling the SASP will have tremendous impacts on our health. However, our understanding of SASP regulation is far from complete. Here, we show that cytoplasmic accumulation of nuclear DNA plays key roles in the onset of SASP. Although both DNase2 and TREX1 rapidly remove the cytoplasmic DNA fragments emanating from the nucleus in pre-senescent cells, the expression of these DNases is downregulated in senescent cells, resulting in the cytoplasmic accumulation of nuclear DNA. This causes the aberrant activation of cGAS-STING cytoplasmic DNA sensors, provoking SASP through induction of interferon-β. Notably, the blockage of this pathway prevents SASP in senescent hepatic stellate cells, accompanied by a decline of obesity-associated hepatocellular carcinoma development in mice. These findings provide valuable new insights into the roles and mechanisms of SASP and possibilities for their control., Activation of DNA damage response induces the acquisition of senescence-associated secretory phenotype (SASP) in senescent cells, but precise mechanisms remain unclear. Here, the authors show that the cytoplasmic accumulation of nuclear DNA activated cytoplasmic DNA sensors to provoke SASP.

We herein report the case of myasthenic crisis occurring in a 51-year-old man. He had experienced ptosis, increased body weight with edema, and fatigue with dyspnea. He presented at our emergency department with disturbed consciousness. He was originally diagnosed with myxedema coma, and he required artificial respiration. Because his weakness persisted and he was positive for anti-acetylcholine receptor antibodies and anti-muscle-specific tyrosine kinase antibodies, we diagnosed myasthenic crisis after various examinations. His clinical response to treatment was good and he was discharged in an ambulatory status 3 months after admission. This case demonstrates that myasthenic crisis may occur in association with myxedema.

Sporadic Creutzfeldt-Jakob disease (sCJD) is classified into six types based on codon 129 polymorphism in the PRNP gene and the protease-resistant prion-related protein, PrP [1,2]. This classification corresponds well with the clinical course and the pathological findings. MM2-cortical type sCJD (MM2C-sCJD) is clinically characterized by slow progressive dementia, increased levels of 14-3-3 protein in the cerebrospinal fluid (CSF), and no periodic synchronous discharge (PSD) in electroencephalography [3]. We report the case of a patient presented with chronic progressive cortical symptoms. Based on the initial clinical findings, corticobasal syndrome (CBS) was suspected although he did not develop akinetic mutism during the lifetime. The postmortem pathological and anatomical findings confirmed MM2C-sCJD. As per the existing diagnostic criteria, our case was difficult to diagnose during the patient’s lifetime. Therefore, this is an important case for considering future revisions of the diagnostic criteria for MM2C-sCJD.

Phospholipase Cϵ (PLCϵ), an effector of Ras and Rap small GTPases, plays a crucial role in inflammation by augmenting proinflammatory cytokine expression. This proinflammatory function of PLCϵ is implicated in its facilitative role in tumor promotion and progression during skin and colorectal carcinogenesis, although their direct link remains to be established. Moreover, the molecular mechanism underlying these functions of PLCϵ remains unknown except that PKD works downstream of PLCϵ. Here we show by employing the colitis-induced colorectal carcinogenesis model, where Apc(Min) (/+) mice are administered with dextran sulfate sodium, that PLCϵ knock-out alleviates the colitis and suppresses the following tumorigenesis concomitant with marked attenuation of proinflammatory cytokine expression. In human colon epithelial Caco2 cells, TNF-α induces sustained expression of proinflammatory molecules and sustained activation of nuclear factor-κB (NF-κB) and PKD, the late phases of which are suppressed by not only siRNA-mediated PLCϵ knockdown but also treatment with a lysophosphatidic acid (LPA) receptor antagonist. Also, LPA stimulation induces these events in an early time course, suggesting that LPA mediates TNF-α signaling in an autocrine manner. Moreover, PLCϵ knockdown results in inhibition of phosphorylation of IκB by ribosomal S6 kinase (RSK) but not by IκB kinases. Subcellular fractionation suggests that enhanced phosphorylation of a scaffolding protein, PEA15 (phosphoprotein enriched in astrocytes 15), downstream of the PLCϵ-PKD axis causes sustained cytoplasmic localization of phosphorylated RSK, thereby facilitating IκB phosphorylation in the cytoplasm. These results suggest the crucial role of the TNF-α-LPA-LPA receptor-PLCϵ-PKD-PEA15-RSK-IκB-NF-κB pathway in facilitating inflammation and inflammation-associated carcinogenesis in the colon.

Two peroxiredoxins, classified as Type II and PrxQ, were characterized in the purple non-sulfur photosynthetic bacterium Rhodobacter sphaeroides. Both recombinant proteins showed remarkable thioredoxin-dependent peroxidase activity with broad substrate specificity in vitro. Nevertheless, PrxQ of R. sphaeroides, unlike typical PrxQs studied to date, does not contain one of the two conserved catalytic Cys residues. We found that R. sphaeroides PrxQ and other PrxQ-like proteins from several organisms conserve a different second Cys residue, indicating that these proteins should be categorized into a novel PrxQ subfamily. Disruption of either the Type II or PrxQ gene in R. sphaeroides had a dramatic effect on cell viability when the cells were grown under aerobic light or oxidative stress conditions created by exogenous addition of reactive oxygen species to the medium. Growth rates of the mutants were significantly decreased compared with that of wild type under aerobic but not anaerobic conditions. These results indicate that the peroxiredoxins are crucial for antioxidative stress response in this bacterium. The gene disruptants also demonstrated reduced levels of photopigment synthesis, suggesting that the peroxiredoxins are directly or indirectly involved in regulated synthesis of the photosynthetic apparatus.

This paper describes a numerical study on the H2/N2 jet diffusion flame interacted with large scale vortices generated by oscillating the fuel velocity. Computations are made of transient diffusion flames. Attentions are paid to the dynamic behavior of the diffusion flames with the transient local extinction and to the flame structure in relation to the local flame parameters such as local flame stretch and preferential diffusion. The obtained results are as follows. (1) When the amplitude of fuel velocity is relatively small, flame extinction does not occur by interaction between flame and vortex, and the temperature characteristics depends on the effect of the preferential diffusion among species and the non-unity Lewis number effect. (2) When the amplitude of fuel velocity is large, the temperature decreases in the region where the stretch rate near the circumferential part of vortex is high. According to the procedure of non-equilibrium of chemical reaction, temperature and heat release rate begins to decrease at the region and the effect results in flame extinction. (3) The position of the local flame extinction does not always agree with that of higher stretch rate. During the procedure of the flame extinction, the position of higher stretch rate moves downstream from the position of extinction. (4) One of the edge flames constructed at the extinction propagates along the stoichiometric line around the vortex to the upstream region, and it is again connected with another edge flame.

In a batchwise variable-pressure/variable-rate expression process, the expression pressure is increased to a predetermined maximum pressure and then held constant until final equilibrium compression is obtained. For analyzing the variable-pressure/variable-rate expression process, the following assumption is made: the internal condition of compressed cake under the instantaneous pressure p in a variable-pressure/variable-rate operation is close to that in a constant-pressure operation under such a pressure p when the same volume of liquid is removed from the same amount of original materials in both operations. Using this assumption, the changes of sample thickness with expression time can be calculated from the analytical equation for the constant-pressure process based on the Terzaghi-Voigt combined model. The match between experiment and theory was satisfactory for the expression of semisolid Korean kaolin.

An understanding of the expansion phenomena of compressed materials is essential to improving the technique of forming by expression in ceramics industries and other processes. In this study, a slurry of Korean kaolin–Solka floc mixture was used as experimental material. The slurry was consolidated in a compression cell at constant pressure, resulting in a semisolid material with uniform void ratio. The expansion process of such a homogeneous material was investigated experimentally and theoretically under the condition in which the compression pressure was released momentarily and the material was saturated with liquid during expansion. Expansion of a homogeneous material is very similar to consolidation of a semisolid material, and can be analyzed well by use of the Terzaghi–Voigt combined model, although the expansion proceeds considerably more slowly than does consolidation under the same change of compression pressure. It is found that the ratio of secondary deformation to total deformation in expansion is much larger than that in consolidation.