Molecular Mechanism of Hyperactivation Conferred by a Truncated TRPA1 Disease Mutant Suggests New Gating Insights

The wasabi receptor, TRPA1, is a non-selective homotetrameric cation channel expressed in primary sensory neurons of the pain pathway, where it is activated by diverse chemical irritants. A direct role for TRPA1 in human health has been highlighted by the discovery of genetic variants associated with severe pain disorders. One such TRPA1 mutant was identified in a father-son pair with cramp fasciculation syndrome (CFS) and neuronal hyperexcitability-hypersensitivity symptoms that may be caused by aberrant channel activity, though the mechanism of action for this mutant is unknown. Here, we show the CFS-associated R919* TRPA1 mutant is functionally inactive when expressed alone in heterologous cells, which is not surprising since it lacks the 201 C-terminal amino acids that house critical channel gating machinery including the pore-lining transmembrane helix. Interestingly, the R919* mutant confers enhanced agonist sensitivity when co-expressed with wild type (WT) TRPA1. This channel hyperactivation mechanism is conserved in distant TRPA1 species orthologues and can be recapitulated in the capsaicin receptor, TRPV1. Using a combination of ratiometric calcium imaging, immunostaining, surface biotinylation, pulldown assays, fluorescence size exclusion chromatography, and proximity biotinylation assays, we show that the R919* mutant co-assembles with WT subunits into heteromeric channels. Within these heteromers, we postulate that R919* TRPA1 subunits contribute to hyperactivation by lowering energetic barriers to channel activation contributed by the missing regions. Additionally, we show heteromer activation can originate from the R919* TRPA1 subunits, which suggests an unexpected role for the ankyrin repeat and coiled coil domains in concerted channel gating. Our results demonstrate the R919* TRPA1 mutant confers gain-of-function thereby expanding the physiological impact of nonsense mutations, reveals a novel and genetically tractable mechanism for selective channel sensitization that may be broadly applicable to other receptors, and uncovers new gating insights that may explain the molecular mechanism of temperature sensing by some TRPA1 orthologues.

Multivariate Analysis Reveals That Unsubstituted β-Ring and C8-Keto Structures Are Important Factors for Anti-Inflammatory Activity of Carotenoids

Carotenoids are natural lipophilic pigments with substantial health benefits. Numerous studies have demonstrated the anti-inflammatory activities of carotenoids, especially toward lipopolysaccharide-induced inflammatory responses. As such, there are few reports on the evaluation and comparison of the anti-inflammatory activities of carotenoids against inflammation induced by other stimuli. In this study, we used pathogen-associated molecular patterns, proinflammatory cytokines, degenerated proteins, and chemical irritants as inflammatory inducers to evaluate the anti-inflammatory activities of eight different carotenoids. Each carotenoid showed characteristic anti-inflammatory activities; thus, we conducted a multivariate analysis to clarify the differences among them. Unsubstituted β-ring (i.e., provitamin A) and C8-keto structures of carotenoids were found to be crucial for their inhibitory effects on the activation of nuclear factor-kappa B and interferon regulatory factors, respectively. Furthermore, we found that β-carotene and echinenone treatment increased intracellular retinoid levels in monocytes and that the retinoids showed the similar activities to β-carotene and echinenone. Taken together, the intake of both provitamin A and C8-keto carotenoids (e.g., siphonaxanthin and fucoxanthin) might be effective in improving the inflammatory status of individuals. A multivariate analysis of anti-inflammatory activities is a useful method for characterizing anti-inflammatory compounds.

Intrapleural Administration With Rh-Endostatin and Chemical Irritants in the Control of Malignant Pleural Effusion: A Systematic Review and Meta-Analysis

IntroductionA modified and recombinant human endostatin (Rh-endostatin) is often used in the control of malignant pleural effusion (MPE) through intrapleural infusion.ObjectivesTo demonstrate the clinical response, survival, and safety of Rh-endostatin plus chemical irritants, their optimal combinations, treatment threshold, and optimal usage, we performed a new systematic review and meta-analysis.MethodologyAll randomized controlled trials (RCTs) were collected from Chinese and English electronic databases (from inception until August 2020). We pooled the data using a series of meta-analyses and summarized the evidence quality following the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.ResultsWe included 75 RCTs recruiting 4,678 patients, which reported six combinations for Rh-endostatin plus chemical irritants. Among the six combinations, only Rh-endostatin plus cisplatin (DDP) with enough trials might improve the complete response [2.29 (1.93, 2.71)] and quality of life [3.01 (2.49, 3.63)] and reduce treatment failure [0.29 (0.25, 0.33)] and progressive disease [0.27 (0.22, 0.34)]. It might not increase the risk of adverse drug reactions. For patients with lung cancer, moderate to massive effusion, initial treatment, Karnofsky Performance Status (KPS) score ≥60, or anticipated survival time ≥3 months, Rh-endostatin (30–45 mg each time, once or twice a week 3–4 times) plus DDP (30–60 mg/m2) obtained a significant improvement in clinical response and a reduction of failure and progressive disease. Most results had good robustness and moderate quality.ConclusionsCurrent evidence suggests that Rh-endostatin with DDP may be an optimal combination, which may improve clinical response and reduce failure and progressive disease with good safety. Rh-endostatin (30–40 mg each time, once or twice a week 3–4 times) with DDP (30–40 mg/m2) may be an optimal usage for achieving an ideal response.

Esophagitis Dissecans Superficialis (EDS) Secondary to Hair Dye Ingestion: Case Report and Literature Review

Esophagitis dissecans superficialis (EDS) is a rare and underdiagnosed esophageal lesion characterized by sloughing of the esophageal mucosa that has been associated with medications, various autoimmune disorders, and exposure to some chemical irritants. Anatomically, EDS is most commonly seen in the middle and distal thirds of the esophagus. When present, EDS is best treated by discontinuing the offending agent and initiating pharmacologic therapy with proton pump inhibitors. Steroids may also be effective if the etiology is autoimmune in nature. Our case highlights a 65-year-old female diagnosed with EDS after incidental ingestion of hair dye containing resorcinol and para-phenylenediamine (PPD).

A prospective study of effectiveness of Mannheim peritonitis index scoring system in predicting the morbidity and mortality in peritonitis due to hollow viscous perforation

Background: Peritonitis is defined as inflammation of the peritoneal cavity, caused by a number of etiologic agents including bacteria, fungi, viruses, chemical irritants, and foreign bodies. The Mannheim peritonitis index (MPI) is one of the simple scoring systems in use that allows the surgeon to easily determine outcome risk. Aims and objective: To estimate outcome of patients with perforation peritonitis. To evaluate effect of MPI score in identification of high risk cases.Methods: A prospective study was conducted in 100 patients with peritonitis due to hollow viscous perforation at surgical unit of tertiary care unit. The duration of study was 2 years. All the data was recorded. Written informed consent was obtained and data was analyzed using appropriate analysis strategy.Results: In this study, total 100 patients enrolled, out of which 54 % patients were in the age group <50 years and 46% patients were in the age group >50 years. Mortality was higher among patients with age group more than 50 years (21%) and in female patients (37.93%). 18 patients had organ failure. 87 patients had preoperative duration was >24 hours. 93% patients had non-colonic origin of sepsis. In 52 (52%) patients total MPI score was <21 while 25 (25%) patients total score was 21-29 and it was >29 in 23 (23%) patients. Mortality was higher among patients with MPI Score more than 29 (95.65%).Conclusions: MPI is accurate to be used with patients with peritonitis and should be considered reliable and simple reference for estimating their risk of death. This study differs in one adverse outcome variables, non-colonic origin of sepsis, we advocate need for further studies on Mannheim peritonitis index to include colonic origin of sepsis.

Identification of compounds producing non-visual photosensation via TRPA1 in zebrafish

ABSTRACTTRPA1 receptors sense chemical irritants, but they do not normally respond to light. Previous studies have identified compounds that confer photosensitivity onto vertebrate TRPA1. However, the pharmacology of TRPA1-mediated non-visual photosensation remains poorly understood. To identify novel compounds that affect this process, we screened a large chemical library for compounds that increased light-elicited motor activity in larval zebrafish. We found structurally diverse hit compounds that were photoreactive and produced specific behavioral phenotypes. A subset of these compounds required functional TRPA1 to produce behavioral phenotypes in vivo. These findings provide novel prototype compounds for controlling TRPA1 with light and improve our understanding of non-visual TRPA1-mediated photosensation.

Intrathoracic infusion therapy of thymic peptides and chemical irritants for malignant pleural effusion: a meta-analysis of 24 randomized controlled trials

Background: To further determine the clinical efficacy and survival of intrathoracic infusion with TPs and chemical irritants and their therapeutic threshold and optimal control regimen to achieve a desired response in malignant pleural effusion (MPE). Methods: We collected all randomized controlled trials (RCTs) of TPs with chemical irritants from Chinese and English databases (from inception until September 2019), and performed a new meta-analysis following the PRISMA guidelines. We measured their bias risk, summarized data using meta-analysis, and evidence quality using the Grades of Recommendation Assessment, Development and Evaluation approach. Results: We collected 24 trials involving three TPs and platinum and 1,592 patients. Most trials had unclear bias risk. TPs with platinum significantly improved complete response [4.02 (3.12 to 5.18)] and quality of life [3.64 (2.34 to 5.66)], the 0.5-year overall survival (OS) rate [5.75 (3.02 to 10.92)], and 1-year OS rate [5.29, (1.71 to 16.36)], and reduced the treatment failure, myelosuppression, and gastrointestinal toxicity. For patients with moderate to large volume of pleural effusion, KPS score ≥50 to 60, or AST ≥3 months, the thymosin (200–300mg/time), thymopentin (2mg/time) or thymosin alpha 1 (3.2mg/time) with cisplatin (30–40mg/m 2 ), carboplatin (400mg/m 2 ), or oxaliplatin (100mg/m 2 ) are possible regimens for achieving a desired success, and low failure. Most results were robust and moderate quality. Conclusion: The moderate evidence suggests that the TPs with platinum is beneficial to the patient with MPE, and provides evidence for the therapeutic threshold and possible regimens that may achieve a desired success and reduce the failure.