Porcine TRIM21 Enhances Porcine Circovirus 2 Infection and Host Immune Responses, But Inhibits Apoptosis of PCV2-Infected Cells

Tripartite motif protein 21 (TRIM21) is an interferon-inducible E3 ligase, containing one RING finger domain, one B-box motif, one coiled-coil domain at the N-terminal, as well as one PRY domain and one SPRY domain at the C-terminal. TRIM21 is expressed in many tissues and plays an important role in systemic autoimmunity. However, TRIM21 plays different roles in different virus infections. In this study, we evaluate the relationship between porcine TRIM21 and PCV2 infection as well as host immune responses. We found that PCV2 infection modulated the expression of porcine TRIM21. TRIM21 can enhance interferons and proinflammatory factors and decrease cellular apoptosis in PCV2-infected cells. These results indicate that porcine TRIM21 plays a critical role in enhancing PCV2 infection, which is a promising target for controlling and developing the treatment of PCV2 infection.

TERT Promoter Revertant Mutation Inhibits Melanoma Growth through Intrinsic Apoptosis

Simple Summary

TERT -146 C>T frequently occurs in many cancer cells. Research targeting the telomerase reverse transcriptase (TERT) promoter contributes to a better understanding of cancer development and treatment. Many conventional cancer treatments aim to develop new drugs targeting TERT. Here, for TERT -146 we converted T to C. The proliferation, migration and invasion of melanoma cells in vitro, and the growth of the tumor in vivo were inhibited. Moreover, the downregulated protein expression of B-cell lymphoma 2 (Bcl-2) indicated that the TERT promoter revertant mutation abrogated the inhibitory effect of mutant TERT on apoptosis. These data elucidated the relationship between the TERT promoter revertant mutations and apoptosis for the first time, and also implied that TERT -146 may be a causal mutation of melanoma. This study provides a new insight into the TERT promoter revertant mutations and apoptosis. The TERT promoter provides preliminary validation of the potential tumor treatment.

Abstract

Human telomerase is a specialized DNA polymerase whose catalytic core includes both TERT and human telomerase RNA (hTR). Telomerase in humans, which is silent in most somatic cells, is activated to maintain the telomere length (TEL) in various types of cancer cells, including melanoma. In the vast majority of tumor cells, the TERT promoter is mutated to promote proliferation and inhibit apoptosis. Here, we exploited NG-ABEmax to revert TERT -146 T to -146 C in melanoma, and successfully obtained TERT promoter revertant mutant cells. These TERT revertant mutant cells exhibited significant growth inhibition both in vitro and in vivo. Moreover, A375^−146C/C cells exhibited telomere shortening and the downregulation of TERT at both the transcription and protein levels, and migration and invasion were inhibited. In addition, TERT promoter revertant mutation abrogated the inhibitory effect of mutant TERT on apoptosis via B-cell lymphoma 2 (Bcl-2), ultimately leading to cell death. Collectively, the results of our work demonstrate that reverting mutations in the TERT promoter is a potential therapeutic option for melanoma.

Free fatty acids impair autophagic activity and activate nuclear factor kappa B signaling and NLR family pyrin domain containing 3 inflammasome in calf hepatocytes

Free fatty acids (FFA)-induced hepatic inflammation agravates liver injury and metabolic dysfunction in dairy cows with ketosis or fatty liver. Under stressful conditions, autophagy is generally considered as a cell protection mechanism, but whether the FFA-induced inflammatory and stress effect on hepatocytes involves an autophagy response is not well known. Thus, the objective of this study was to investigate the effects of FFA on autophagy and the role of autophagy in the activation of NF-κB (nuclear factor kappa B) signaling and NLRP3 (NLR family pyrin domain containing 3) inflammasome in calf hepatocytes. Calf hepatocytes were isolated from 3 healthy Holstein female new-born calves (1 d of age, 30-40 kg) and exposed to various concentrations of FFA (0, 0.3, 0.6, or 1.2 mM) after treatment with or without the autophagy inhibitor chloroquine (CQ) or the autophagy activator rapamycin. Expression of autophagy markers, LC3 (microtubule-associated protein 1 light chain 3) and p62 (sequestosome 1), NF-κB signaling, and NLRP3 inflammasome-related molecules were analyzed via western blot and quantitative real-time PCR. Results revealed that 0.6 and 1.2 mM FFA activated NF-κB signaling and NLRP3 inflammasome as indicated by an elevated ratio of p-NF-κB/NF-κB, protein abundance of NLRP3 and CASP1 (caspase 1), activity of CASP1, and mRNA abundance of IL1B and IL18. In addition, hepatocyte treated with 0.6 and 1.2 mM FFA or autophagy inhibitor CQ displayed increased protein abundance of p62 and LC3-II. Moreover, there was no difference in protein abundance of p62 and LC3-II between calf hepatocytes treated with 1.2 mM FFA and 1.2 mM FFA plus CQ, indicating that FFA inhibits autophagic activity in calf hepatocytes. Treatment with CQ led to overactivation of NF-κB signaling and NLRP3 inflammasome. Furthermore, CQ plus 1.2 mM FFA aggravated FFA-induced inflammation. In contrast, induction of autophagy by rapamycin ameliorated the FFA-activated NF-κB signaling and NLRP3 inflammasome as demonstrated by a lower ratio of p-NF-κB/NF-κB, protein abundance of NLRP3 and CASP1, activity of CASP1, and mRNA abundance of IL1B and IL18. Overall, inhibition of autophagy exacerbated, whereas induction of autophagy alleviated, FFA-induced inflammatory processes in calf hepatocytes, suggesting that impairment of autophagy might be partly responsible for hepatic inflammation and subsequent liver injury in dairy cows with ketosis or fatty liver. As such, regulation of autophagy may be an effective therapeutic strategy for controlling overt inflammatory responses in vivo.

Investigation of the lncRNA THOR in Mice Highlights the Importance of Noncoding RNAs in Mammalian Male Reproduction

THOR is a highly conserved testis-specific long noncoding RNA (lncRNA). The interaction between THOR and the development of the male reproductive system remains unclear. Herein, CRISPR/Cas9 technology was used to establish a stable THOR-deficient mouse model, and the relationship between THOR and the fertility of adult male mice was investigated. The male mice in which THOR was deleted were smaller than the WT male mice. Moreover, their survival rate was reduced by 60%, their fertility was reduced by 50%, their testicular size and sperm motility were reduced by 50%, their testicular cell apoptosis was increased by 7-fold, and their ratio of female-to-male offspring was imbalanced (approximately 1:3). Furthermore, to elucidate the mechanisms of male reproductive system development, the mRNA levels of THOR targets were measured by qRT-PCR. Compared with WT mice, the THOR-deficient mice exhibited significantly decreased mRNA levels of IGF2BP1, c-MYC, IGF1, and IGF2. MEK-ERK signaling pathway expression was downregulated as determined by Western blot. We found that THOR targeted the MER-ERK signaling pathway downstream of IGF2 by binding to IGF2BP1 and affected testicular and sperm development in male mice. These results may also provide perspectives for exploring the roles of lncRNAs in human reproductive development and the pathogenesis and potential therapeutic targets of infertility.

Pathological alterations in the gastrointestinal tract of a porcine model of DMD

Background

Patients with Duchenne muscular dystrophy (DMD) develop severe skeletal and cardiac muscle pathologies, which result in premature death. Therefore, the current therapeutic efforts are mainly targeted to correct dystrophin expression in skeletal muscle and heart. However, it was reported that DMD patients may also exhibit gastrointestinal and nutritional problems. How the pathological alterations in gastrointestinal tissues contribute to the disease are not fully explored.

Results

Here we employed the CRISPR/Cas9 system combined with somatic nuclear transfer technology (SCNT) to establish a porcine model of DMD and explored their pathological alterations. We found that genetic disruption of dystrophin expression led to morphological gastrointestinal tract alterations, weakened the gastrointestinal tract digestion and absorption capacity, and eventually led to malnutrition and gastric dysfunction in the DMD pigs.

Conclusions

This work provides important insights into the pathogenesis of DMD and highlights the need to consider the gastrointestinal dysfunction as an additional therapeutic target for DMD patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-021-00647-9.

Possible Targets of Pan-Coronavirus Antiviral Strategies for Emerging or Re-Emerging Coronaviruses

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), which caused Coronaviruses Disease 2019 (COVID-19) and a worldwide pandemic, is the seventh human coronavirus that has been cross-transmitted from animals to humans. It can be predicted that with continuous contact between humans and animals, more viruses will spread from animals to humans. Therefore, it is imperative to develop universal coronavirus or pan-coronavirus vaccines or drugs against the next coronavirus pandemic. However, a suitable target is critical for developing pan-coronavirus antivirals against emerging or re-emerging coronaviruses. In this review, we discuss the latest progress of possible targets of pan-coronavirus antiviral strategies for emerging or re-emerging coronaviruses, including targets for pan-coronavirus inhibitors and vaccines, which will provide prospects for the current and future research and treatment of the disease.

CRISPR/Cas9-Mediated Specific Integration of Fat-1 and IGF-1 at the pRosa26 Locus

Many researchers have focused on knock-in pigs for site-specific integration, but little attention has been given to genetically modified pigs with the targeted integration of multiple recombinant genes. To establish a multigene targeted knock-in editing system, we used the internal ribosome entry site (IRES) and self-cleaving 2A peptide technology to construct a plasmid coexpressing the fatty acid desaturase (Fat-1) and porcine insulin-like growth factor-1 (IGF-1) genes at equal levels. In this study, pigs were genetically modified with multiple genes that were precisely inserted into the pRosa26 locus by using the clustered regularly spaced short palindrome repeat sequence (CRISPR)/CRISPR-related 9 (Cas9) system and somatic cell nuclear transfer technology (SCNT) in combination. Single copies of the Fat-1 and IGF-1 genes were expressed satisfactorily in various tissues of F0-generation pigs. Importantly, gas chromatography analysis revealed a significantly increased n-3 polyunsaturated fatty acid (PUFA) level in these genetically modified pigs, which led to a significant decrease of the n-6 PUFA/n-3 PUFA ratio from 6.982 to 3.122 (*** p < 0.001). In conclusion, the establishment of an editing system for targeted double-gene knock-in in this study provides a reference for the precise integration of multiple foreign genes and lays a foundation for the development of new transgenic pig breeds with multiple excellent phenotypes.

HMEJ-mediated site-specific integration of a myostatin inhibitor increases skeletal muscle mass in porcine

As a robust antagonist of myostatin (MSTN), follistatin (FST) is an important regulator of skeletal muscle development, and the delivery of FST to muscle tissue represents a potential therapeutic strategy for muscular dystrophies. The N terminus and FSI domain of FST are the functional domains for MSTN binding. Here, we aimed to achieve site-specific integration of FSI-I-I, including the signal peptide, N terminus, and three FSI domains, into the last codon of the porcine MSTN gene using a homology-mediated end joining (HMEJ)-based strategy mediated by CRISPR-Cas9. Based on somatic cell nuclear transfer (SCNT) technology, we successfully obtained FSI-I-I knockin pigs. H&E staining of longissimus dorsi and gastrocnemius cross-sections showed larger myofiber sizes in FSI-I-I knockin pigs than in controls. Moreover, the Smad and Erk pathways were inhibited, whereas the PI3k/Akt pathway was activated in FSI-I-I knockin pigs. In addition, the levels of MyoD, Myf5, and MyoG transcription were upregulated while that of MRF4 was downregulated in FSI-I-I knockin pigs. These results indicate that the FSI-I-I gene mediates skeletal muscle hypertrophy through an MSTN-related signaling pathway and the expression of myogenic regulatory factors. Overall, FSI-I-I knockin pigs with hypertrophic muscle tissue hold great promise as a therapeutic model for human muscular dystrophies.

Swine sperm induces neutrophil extracellular traps that entangle sperm and embryos

Sperm motility, fertilization and embryo implantation are several important factors in reproduction. Except healthy state of sperm and embryo themselves, successful pregnancy is closely related to the status of female reproductive tract immune system. Increased immune cells in reproductive tract often leads to low sperm motility and low chance of embryo implantation, but the mechanisms remain not well clarified. The aim of this study is to investigate the direct effects of swine polymorphonuclear neutrophils (PMNs) on sperm or embryo in vitro and then try to clarify the molecular mechanisms undergoing the phenomenon. Swine sperm-triggered neutrophil extracellular traps (NETs) were observed by scanning electron microscopy (SEM). PMNs phagocytosis of sperms was examined by transmission electron microscopy (TEM). Sperm-triggered NETs were quantitated by Pico Green®. Vital staining of the interaction between PMNs and embryo were observed by using confocal microscope. It was showed that PMNs were directly activated by sperm in the form of phagocytosis or casting NETs and that sperm-triggered-NETs formation was made up with DNA co-located with citrullinated histone 3 (citH3) and myeloperoxidase (MPO). In addition, the potential mechanism of NETs release was relevant to NADPH oxidase, ERK1/2 or p38 MAPK signaling pathways. Of great interest was that swine embryo was first found entangled in NETs in vitro, but the function and mechanism of this action in vivo fertilization still needed further investigation. In conclusion, this is the first report about swine sperm-induced NETs that entangle sperm and embryo, which might provide an entirely understanding of swine reproductive physiology and immunology.

Pediatric allergic rhinitis with functional gastrointestinal disease: Associations with the intestinal microbiota and gastrointestinal peptides and therapeutic effects of interventions

Children are susceptible to allergic rhinitis (caused by external allergens) accompanied by functional gastrointestinal disease, which seriously affects physical and mental health. Antihistamines and nasal spray hormones are commonly used in clinical treatment, but these drugs often have unsatisfactory efficacy and result in high recurrence rates. Therefore, understanding the pathogenesis of allergic rhinitis with functional gastrointestinal disease and seeking safer treatment and prevention methods is essential. Herein, molecular ecology and immunoassays were used to analyze correlations between pediatric allergic rhinitis with functional gastrointestinal disease and both the intestinal microbiota and gastrointestinal peptide levels. Fifty healthy children (healthy group) and 80 children with allergic rhinitis with functional gastrointestinal disease (case group: evenly divided into a control group (conventional drug therapy) and an intervention group (conventional drug therapy + glutamine+probiotics)), were enrolled. Bifidobacterium and Lactobacillus counts and the gastrin and motilin levels were lower in the case group than in the healthy group, whereas Enterobacter, yeast, and Enterococcus counts and the somatostatin, serotonin, and vasoactive intestinal peptide levels were higher. Post treatment, intestinal microbiota indices, gastrointestinal peptide levels, and intestinal barrier function were better in the intervention group than in the control group (p < 0.05). The intervention group had a significantly higher total therapeutic response rate (95.00%) than the control group (77.50%). The intestinal microbiota was closely associated with gastrointestinal peptide levels. Treatment with glutamine and probiotics regulated these levels, re-established balance in the intestinal microbiota, and restored intestinal barrier function.

Propionate alleviates palmitic acid-induced endoplasmic reticulum stress by enhancing autophagy in calf hepatic cells

Negative energy balance-induced high blood concentrations of free fatty acids during the early postpartum period in dairy cows is a major cause of liver injury. Cows in severe negative energy balance often have suboptimal intakes of feed, which contributes to shortfalls in production of ruminal propionate and circulating glucose. Although increasing propionate production by the rumen through feed additives such as propylene glycol is effective in helping cows alleviate the shortfall in dietary energy supply, mechanisms whereby propionate affects liver function beyond gluconeogenesis are unknown. Therefore, the objective of this study was to investigate whether propionate could protect calf hepatic cells from palmitic acid (PA)-induced lipotoxicity and the underlying mechanisms. Calf hepatic cells were isolated from 5 healthy calves (1 d old, female, 30-40 kg, fasting) and treated with various concentrations of PA (0, 100, 200, or 400 μM) and propionate (0, 1, 2, or 4 mM) after being administered with or without autophagic inhibitor. Propionate enhanced autophagic activity in calf hepatic cells, as indicated by elevated expression of autophagy markers LC3-II (microtubule-associated protein 1 light chain 3-II, encoded by MAP1LC3) and decreased expression of SQSTM1 (sequestosome-1, also called p62). Conversely, PA suppressed autophagic activity and decreased cell viability, which was improved by propionate in calf hepatic cells. In addition, propionate decreased the phosphorylation of proteins EIF2AK3 (kinase R/PKR like ER kinase) and ERN1 (inositol-requiring enzyme 1α) and cleaved ATF6 (activating transcription factor 6) in PA-treated calf hepatic cells, indicating the suppression effect of propionate on endoplasmic reticulum (ER) stress. However, inhibition of autophagic activity by chloroquine or bafilomycin A1 impede the beneficial effects of propionate on ER stress and cell viability. These results demonstrated that propionate alleviates ER stress and elevates cell viability in PA-treated calf hepatic cells by enhancing autophagy, which implies that autophagy may be a promising target in improving liver injury of dairy cows during transition period.

Pig Cloning Using Somatic Cell Nuclear Transfer

Porcine cloning technology can be used to produce progenies genetically identical to the donor cells from high-quality breeding pigs. In addition, genetically modified pigs have been produced by somatic cell nuclear transfer using genetically modified porcine fetal fibroblasts. The method of preparing genetically modified pigs is critical for establishing pig models for human diseases, and for generating donor animals for future xenotransplantation. This chapter describes detailed procedures for generating cloned pigs using fetal fibroblasts as nuclear donors.

CRISPR/Cas9-mediated knockin of human factor IX into swine factor IX locus effectively alleviates bleeding in hemophilia B pigs

Hemophilia B is an X-linked recessive bleeding disorder caused by abnormalities in the coagulation factor IX gene. Without prophylactic treatment, patients experience frequent spontaneous bleeding episodes. Well-characterized animal models are valuable for determining the pathobiology of the disease and for testing novel therapeutic innovations. Here, we generated a porcine model of hemophilia B (HB) using a combination of CRISPR/Cas9 and somatic cell nuclear transfer. We also tested the possibility of HB therapy by gene insertion. Frequent spontaneous joint bleeding episodes that occurred in HB pigs allowed a thorough investigation of the pathological process of hemophilic arthropathy. In contrast to the HB pigs, which showed a severe bleeding tendency and joint damage, the transgenic pigs carrying human coagulation factor IX exhibited a partial improvement in bleeding. In summary, this study not only offers a translational HB model for exploring the pathological process of hemophilic arthropathy, but also provides a possibility for the permanent correction of hemophilia in the future by genome editing in situ.

[MRI associated biomarker analysis for diagnosis of lymph node metastasis in T1-2 stage rectal cancer]

Objective: To explore the diagnostic accuracy improved by magnetic resonance imaging (MRI) biomarkers for lymph node metastasis in T1-2 stage rectal cancer before treatment. Methods: Medical records of 327 patients with T1-2 rectal cancer who underwent pretreatment MRI and rectal tumor resection between January 2015 and November 2019 were retrospectively analyzed. Fifty-seven cases were divided into the lymph node metastasis group (N+ group) while other 270 cases in the non-lymph node metastasis group (N-group) according to the pathologic diagnosis. Two radiologist evaluated the tumor characteristics of MRI images. The relationship of the clinical and imaging characteristics of lymph node metastasis was assessed by using univariate analysis and multivariable logistic regression analysis. Receiver operating characteristic (ROC) curve was used to evaluate the diagnostic abilities for the differentiation of N- from N+ tumors. Results: Among the 327 patients, MR-N evaluation was positive in 67 cases, which was statistically different from the pathological diagnosis (P<0.001). The sensitivity, specificity and accuracy of MRI for lymph node metastasis were 45.6%, 84.8% and 78.0%, respectively. Multivariate regression analysis showed that tumor morphology (P=0.002), including mucus or not (P<0.001), and MR-N evaluation (P<0.001) were independent influencing factors for stage T1-2 rectal cancer with lymph node metastasis. The area under the ROC curve of rectal cancer with lymph node metastasis analyzed by the logistic regression model was 0.786 (95%CI: 0.720~0.852). Conclusions: Tumor morphology, including mucus or not, and MR-N evaluation can serve as independent biomarkers for differentiation of N- and N+ tumors. The model combined with these biomarkers facilitates to improve the diagnostic accuracy of lymph node metastasis in T1-2 rectal cancers by using MRI.

Hepatic autophagy and mitophagy status in dairy cows with subclinical and clinical ketosis

Severe negative energy balance around parturition is an important contributor to ketosis, a metabolic disorder that occurs most frequently in the peripartal period. Autophagy and mitophagy are important processes responsible for breaking down useless or toxic cellular material, and in particular damaged mitochondria. However, the role of autophagy and mitophagy during the occurrence and development of ketosis is unclear. The objective of this study was to investigate autophagy and mitophagy in the livers of cows with subclinical ketosis (SCK) and clinical ketosis (CK). We assessed autophagy by measuring the protein abundance of microtubule-associated protein 1 light chain 3-II (LC3-II; encoded by MAP1LC3) and sequestosome-1 (p62, encoded by SQSTM1), as well as the mRNA abundance of autophagy-related genes 5 (ATG5), 7 (ATG7), and 12 (ATG12), beclin1 (BECN1), and phosphatidylinositol 3-kinase catalytic subunit type 3 (PIK3C3). Mitophagy was evaluated by measuring the protein abundance of the mitophagy upstream regulators PTEN-induced putative kinase 1 (PINK1) and Parkin. Liver and blood samples were collected from healthy cows [n = 15; blood β-hydroxybutyrate (BHB) concentration <1.2 mM], cows with SCK (n = 15; blood BHB concentration 1.2 to 3.0 mM) and cows with CK (n = 15; blood BHB concentration >3.0 mM with clinical signs) with similar lactation numbers (median = 3, range = 2 to 4) and days in milk (median = 6, range = 3 to 9). The serum activity of aspartate aminotransferase and alanine aminotransferase was greater in cows with CK than in healthy cows. Levels of oxidative stress biomarkers malondialdehyde and hydrogen peroxide were also higher in liver tissue from ketotic cows (SCK and CK) than from healthy cows. Compared with cows with CK and healthy cows, the hepatic mRNA abundance of MAP1LC3, SQSTM1, ATG5, ATG7, ATG12, and PIK3C3 was upregulated in cows with SCK. Compared with healthy cows, cows with SCK had a lower abundance of p62 and a greater abundance of LC3-II, but levels of both were higher in cows with CK. The mRNA abundance of ATG12 was lower in cows with CK than in healthy cows. Furthermore, the hepatic protein abundance of PINK1 and Parkin was greater in cows with SCK and slightly lower in cows with CK than in healthy cows. These data demonstrated differences in the hepatic activities of autophagy and mitophagy in cows with SCK compared with cows with CK. Although the precise mechanisms for these differences could not be discerned, autophagy and mitophagy seem to be involved in ketosis.

Generation of a pHSPA6 gene-based multifunctional live cell sensor

Biosensors utilizing intact live cells can report responses to certain stimuli rapidly and sensitively and have attracted a great deal of attention. The expression pattern of HSPA6, a little studied HSPA family member, has contributed to the development of multifunctional and intelligent whole-cell sensors. Herein, a new pHSPA6-based EGFP fluorescent reporter cell line was designed and developed via a CRISPR/Cas9-mediated knock-in strategy. The fluorescent reporter cell line has a precise EGFP integration site and gene copy number, and no selectable marker genes were introduced during the selection processes. Stimulation experiments with HSPA6-specific stressors indicated that EGFP fluorescent reporter cells could rapidly and effectively convert stress signals into EGFP fluorescent signals. Furthermore, cell proliferation and gene expression pattern analysis showed that the fluorescent reporter cells grew well and that both the integrated EGFP gene and the pHSPA6 gene were expressed rapidly and sensitively in response to stimulation. This study provides a new strategy for the construction of a cell model for HSPA6 expression/interaction and an intelligent live cell sensor, which can potentially be applied to numerous fields, such as those focusing on cellular models of HSPA6 signaling cascades, biomaterials, food security, environmental assessment, and drug screening.

Pyroptosis executioner gasdermin D contributes to host defense and promotes Th 1 immune response during Neospora caninum infection

Neospora caninum (N. caninum) is an intracellular parasite and is the causative agent of neosporosis, which leads to reproductive failure in cattle. Pyroptosis is a recently discovered form of programmed cell death executed by gasdermin D (GSDMD). This cell death mechanism is an important host defense against intracellular pathogens. However, pyroptosis induced by N. caninum is poorly understood. The aim of this study was to explore the roles of GSDMD-mediated pyroptosis during N. caninum infection in vivo. N. caninum-infected wild type mice and GSDMD-deficient mice were used to evaluate host resistance and its ability to affect immune response against this parasite. The results showed that GSDMD deficiency significantly reduced survival and impaired the host's abilities to clear parasite loads in tissues, monocytes/macrophages and neutrophils. Additionally, GSDMD was essential for circulating IL-18 and IFN-γ production induced by N. caninum infection, indicating that GSDMD can mediate the Th 1 immune response against N. caninum infection. Additional data revealed that treatment with exogenous recombinant IL-18 in N. caninum-infected Gsdmd^-/- mice rescues the reduction of circulating IFN-γ production to help eliminate the parasite. Taken together, our data indicate that GSDMD-mediated pyroptosis plays a vital role in maintaining host resistance to N. caninum and is essential for clearing the parasite. This form of programmed cell death promotes the Th 1 immune response by controlling IL-18 release and is considered a host defense against N. caninum. This study expands our understanding of interactions between host immune response/defense and N. caninum infection.

A CRISPR-engineered swine model of COL2A1 deficiency recapitulates altered early skeletal developmental defects in humans

Loss-of-function mutations in the COL2A1 gene were previously described as a cause of type II collagenopathy (e.g., spondyloepiphyseal dysplasia, Stickler syndrome type I), a major subgroup of genetic skeletal diseases. However, the pathogenic mechanisms associated with COL2A1 mutations remain unclear, and there are few large-mammal models of these diseases. In this study, we established a swine model carrying COL2A1 mutations using CRISPR/Cas9 and somatic cell nuclear transfer technologies. Animals mutant for COL2A1 exhibited severe skeletal dysplasia characterized by shortened long bones, abnormal vertebrae, depressed nasal bridge, and cleft palate. Importantly, COL2A1 mutant piglets suffered tracheal collapse, which was almost certainly the cause of their death shortly after birth. In conclusion, we have demonstrated for the first time that overt and striking skeletal dysplasia occurring in human patients can be recapitulated in large transgenic mammals. This model underscores the importance of employing large animals as models to investigate the pathogenesis and potential therapeutics of skeletal diseases.

The impact of stroke on bone properties and muscle-bone relationship: a systematic review and meta-analysis

To systematically review available evidence related to the characteristics of bone changes post-stroke and the relationship between various aspects of muscle function (e.g., strength, spasticity) and bone properties after stroke onset. An extensive online database search was undertaken (last search in January 2019). Articles that examined the bone properties in stroke patients were included. The quality of the studies was evaluated with the National Institutes of Health (NIH) Study Quality Assessment Tools. Publication bias of meta-analyses was assessed using the Egger's regression asymmetry test. The selection and evaluation of the articles were conducted by two independent researchers. Fifty-nine studies were identified. In subacute and chronic stroke studies, the skeletal sites in the paretic limbs sustained a more pronounced decline in bone quality than did their counterparts in the non-paretic limbs. The rate of changes showed a decelerating trend as post-stroke duration increased, but the timing of achieving the steady rate differed across skeletal sites. The magnitude of bone changes in the paretic upper limb was more pronounced than the paretic lower limb. There was a strong relationship between muscle strength/mass and bone density/strength index. Muscle spasticity seemed to have a negative impact on bone integrity in the paretic upper limb, but its influence on bone properties in the paretic lower limb was uncertain. Substantial bone changes in the paretic limbs occurred particularly in the first few months after stroke onset. Early intervention, muscle strength training, and long-term management strategies may be important to enhance bone health post-stroke. This review has also revealed the knowledge gaps which should be addressed in future research.

Efficient base editing by RNA-guided cytidine base editors (CBEs) in pigs

Cytidine base editors (CBEs) have been demonstrated to be useful for precisely inducing C:G-to-T:A base mutations in various organisms. In this study, we showed that the BE4-Gam system induced the targeted C-to-T base conversion in porcine blastocysts at an efficiency of 66.7-71.4% via the injection of a single sgRNA targeting a xeno-antigen-related gene and BE4-Gam mRNA. Furthermore, the efficiency of simultaneous three gene base conversion via the injection of three targeting sgRNAs and BE4-Gam mRNA into porcine parthenogenetic embryos was 18.1%. We also obtained beta-1,4-N-acetyl-galactosaminyl transferase 2, alpha-1,3-galactosyltransferase, and cytidine monophosphate-N-acetylneuraminic acid hydroxylase deficient pig by somatic cell nuclear transfer, which exhibited significantly decreased activity. In addition, a new CBE version (termed AncBE4max) was used to edit genes in blastocysts and porcine fibroblasts (PFFs) for the first time. While this new version demonstrated a three genes base-editing rate of 71.4% at the porcine GGTA1, B4galNT2, and CMAH loci, it increased the frequency of bystander edits, which ranged from 17.8 to 71.4%. In this study, we efficiently and precisely mutated bases in porcine blastocysts and PFFs using CBEs and successfully generated C-to-T and C-to-G mutations in pigs. These results suggest that CBEs provide a more simple and efficient method for improving economic traits, reducing the breeding cycle, and increasing disease tolerance in pigs, thus aiding in the development of human disease models.