Human NLRP1 is a sensor of pathogenic coronavirus 3CL proteases in lung epithelial cells.

Inflammation observed in SARS-CoV-2-infected patients suggests that inflammasomes, proinflammatory intracellular complexes, regulate various steps of infection. Lung epithelial cells express inflammasome-forming sensors and constitute the primary entry door of SARS-CoV-2. Here, we describe that the NLRP1 inflammasome detects SARS-CoV-2 infection in human lung epithelial cells. Specifically, human NLRP1 is cleaved at the Q333 site by multiple coronavirus 3CL proteases, which triggers inflammasome assembly and cell death and limits the production of infectious viral particles. Analysis of NLRP1-associated pathways unveils that 3CL proteases also inactivate the pyroptosis executioner Gasdermin D (GSDMD). Subsequently, caspase-3 and GSDME promote alternative cell pyroptosis. Finally, analysis of pyroptosis markers in plasma from COVID-19 patients with characterized severe pneumonia due to autoantibodies against, or inborn errors of, type I interferons (IFNs) highlights GSDME/caspase-3 as potential markers of disease severity. Overall, our findings identify NLRP1 as a sensor of SARS-CoV-2 infection in lung epithelia.

Salmonella Flagellin Activates NAIP/NLRC4 and Canonical NLRP3 Inflammasomes in Human Macrophages.

Infection of human macrophages with Salmonella enterica serovar Typhimurium (S. Typhimurium) leads to inflammasome activation. Inflammasomes are multiprotein complexes facilitating caspase-1 activation and subsequent gasdermin D-mediated cell death and IL-1ß and IL-18 cytokine release. The NAIP/NLRC4 inflammasome is activated by multiple bacterial protein ligands, including flagellin from the flagellum and the needle protein PrgI from the S. Typhimurium type III secretion system. In this study, we show that transfected ultrapure flagellin from S Typhimurium induced cell death and cytokine secretion in THP-1 cells and primary human monocyte-derived macrophages. In THP-1 cells, NAIP/NLRC4 and NLRP3 played redundant roles in inflammasome activation during infection with S. Typhimurium. Knockout of NAIP or NLRC4 in THP-1 cells revealed that flagellin, but not PrgI, now activated the NLRP3 inflammasome through a reactive oxygen species- and/or cathepsin-dependent mechanism that was independent of caspase-4/5 activity. In conclusion, our data suggest that NLRP3 can be activated by flagellin to act as a "safety net" to maintain inflammasome activation under conditions of suboptimal NAIP/NLRC4 activation, as observed in THP-1 cells, possibly explaining the redundant role of NLRP3 and NAIP/NLRC4 during S. Typhimurium infection.

Development and characterization of a technique for percutaneous radiologic gastrojejunostomy tube placement in the dog.

OBJECTIVE: To develop and describe a technique for percutaneous radiologic gastrojejunostomy tube placement in the dog. DESIGN: Prospective technique development study. SETTING: University teaching hospital. ANIMALS: Six healthy adult male Beagles. INTERVENTIONS: Following anesthetic induction, fluoroscopic and ultrasound guidance were used to identify an appropriate gastropexy site on the left lateral abdomen. Gastropexy was performed using gastrointestinal suture anchors. An over-the-wire catheter technique using fluoroscopic guidance was used to achieve jejunal access. An 18F/8F, 58 cm, dual-lumen gastrojejunal feeding tube was placed via serial over-the-wire dilation of the body wall using an 18F peel-away introducer kit. Tube location was determined radiographically immediately following placement and on days 2, 4, after emesis on day 4, and at time of gastrojejunal feeding tube removal (day 16-18). MEASUREMENTS AND MAIN RESULTS: Percutaneous radiologic gastrojejunostomy (PRGJ) tube placement was successful in all dogs. Median time to pyloric passage with the guide wire was 23.5 minutes (range, 9-93 minutes). Median total procedure time was 53 minutes (range, 49-113 minutes). Significant tube migration was not observed at any point during the study. One dog developed linear foreign body obstruction secondary to the tube on day 5 that was relieved by release of the jejunal component. Other complications were minor and included mild-to-moderate peristomal inflammation in all dogs and removal of the feeding tube on day 3 by 1 dog. Feedings were well tolerated in all dogs. CONCLUSIONS: PRGJ tube placement in the dog is a safe and minimally invasive technique that allows for jejunal feeding without surgery or endoscopy. The high success rates, acceptable procedural times, and minimal complications are appealing for use in critically ill patients. Although additional evaluations are needed, PRGJ tube placement may be considered for dogs that require postpyloric feeding with or without gastric decompression.

Endoscopic placement of ureteral stents for treatment of congenital bilateral ureteral stenosis in a dog.

CASE DESCRIPTION: A 5-year-old 8.6-kg (18.9-lb) spayed female Pug was evaluated because of chronic hematuria and recurrent urinary tract infections. CLINICAL FINDINGS: Excretory urography, ultrasonography, and excretory CT urography were performed. Results indicated that the dog had bilateral hydronephrosis and hydroureter and suspected proximal ureteral stenosis. Retrograde ureteropyelography confirmed the presence of stenosis at the ureteropelvic junction of each ureter, along with a large amount of endoluminal ureteral debris. Clinical findings suggested that the dog had a congenital bilateral anomaly of the upper urinary tract. TREATMENT AND OUTCOME: The dog was anesthetized, and 2 double-pigtail ureteral stents were placed cystoscopically with fluoroscopic guidance for immediate relief of the ureteropelvic junction obstructions. Each stent extended from the left or right renal pelvis to the urinary bladder. The procedures and the patient's recovery from anesthesia were uncomplicated. Continuing improvements in severity of hydronephrosis, hydroureter, and dysuria were evident during routine follow-up examinations at 2, 4, 12, 16, and 45 weeks after stent placement. Over the subsequent 12 months, all clinical signs remained resolved other than a urinary tract infection that was successfully treated with antimicrobials. CLINICAL RELEVANCE: Ureteral stenosis should be considered as a differential diagnosis for hydronephrosis in dogs, particularly when urinary tract calculi or neoplasia is not present. Chronic hematuria and recurrent urinary tract infections can be associated with this condition. Placement of ureteral stents may be a successful treatment option for ameliorization of congenital ureteral obstructions.

Effects of negative pressure wound therapy on healing of open wounds in dogs.

OBJECTIVE: To compare the effect of negative pressure wound therapy (NPWT) with standard-of-care management on healing of acute open wounds in dogs. STUDY DESIGN: Prospective, controlled, experimental study. ANIMALS: Adult dogs (n=10). METHODS: Full-thickness 4 m × 2 m wounds were surgically created on each antebrachium and in each dog were randomized to receive either NPWT or standard wound dressings (CON) for 21 days. Dressing changes and wound evaluations were made at 8 time points. First appearance of granulation tissue, smoothness of granulation tissue, exuberance, percent epithelialization, and percent contraction were compared. Biopsies for histopathology were taken, and histologic scores determined, at 5 time points, and aerobic bacterial wound cultures performed at 2 time points. RESULTS: Granulation tissue appeared significantly earlier, and was smoother and less exuberant in NPWT wounds compared with CON wounds. Percent contraction in NPWT wounds was less than CON wounds after Day 7. Percent epithelialization in NPWT wounds was less than CON wounds on Days 11, 16, 18, and 21. Histologic scores for acute inflammation were higher in NPWT on Day 3, and lower on Day 7, than CON wounds. Bacterial load was higher in NPWT on Day 7. CONCLUSION: NPWT accelerated appearance of smooth, nonexuberant granulation tissue; however, prolonged use of NPWT impaired wound contraction and epithelialization.