Bidirectional transcription at the PPP2R2B gene locus in spinocerebellar ataxia type 12.

OBJECTIVE: Spinocerebellar ataxia type 12 (SCA12) is a neurodegenerative disease caused by expansion of a CAG repeat in the PPP2R2B gene . Here we tested the hypothesis that the PPP2R2B antisense ( PPP2R2B-AS1 ) transcript containing a CUG repeat is expressed and contributes to SCA12 pathogenesis. METHODS: Expression of PPP2R2B-AS1 transcript was detected in SCA12 human induced pluripotent stem cells (iPSCs), iPSC-derived NGN2 neurons, and SCA12 knock-in mouse brains using strand-specific RT-PCR (SS-RT-PCR). The tendency of expanded PPP2R2B-AS1 ( expPPP2R2B-AS1 ) RNA to form foci, a marker of toxic processes involving mutant RNAs, was examined in SCA12 cell models by fluorescence in situ hybridization. The toxic effect of expPPP2R2B-AS1 transcripts on SK-N-MC neuroblastoma cells was evaluated by caspase 3/7 activity. Western blot was used to examine the expression of repeat associated non-ATG-initiated (RAN) translation of expPPP2R2B-AS1 transcript in SK-N-MC cells. RESULTS: The repeat region in PPP2R2B gene locus is bidirectionally transcribed in SCA12 iPSCs, iPSC-derived NGN2 neurons, and SCA12 mouse brains. Transfected expPPP2R2B-AS1 transcripts are toxic to SK-N-MC cells, and the toxicity may be mediated, at least in part, by the RNA secondary structure. The expPPP2R2B-AS1 transcripts form CUG RNA foci in SK-N-MC cells. expPPP2R2B-AS1 transcript is translated in the Alanine ORF via repeat-associated non-ATG (RAN) translation, which is diminished by single nucleotide interruptions within the CUG repeat, and MBNL1 overexpression. INTERPRETATION: These findings suggest that PPP2R2B-AS1 contributes to SCA12 pathogenesis, and may therefore provide a novel therapeutic target for the disease.

Adipokine C1q/Tumor Necrosis Factor- Related Protein 3 (CTRP3) Attenuates Intestinal Inflammation Via Sirtuin 1/NF-κB Signaling.

BACKGROUND & AIMS: The adipokine CTRP3 has anti-inflammatory effects in several nonintestinal disorders. Although serum CTRP3 is reduced in patients with inflammatory bowel disease (IBD), its function in IBD has not been established. Here, we elucidate the function of CTRP3 in intestinal inflammation. METHODS: CTRP3 knockout (KO) and overexpressing transgenic (Tg) mice, along with their corresponding wild-type littermates, were treated with dextran sulfate sodium for 6-10 days. Colitis phenotypes and histologic data were analyzed. CTRP3-mediated signaling was examined in murine and human intestinal mucosa and mouse intestinal organoids derived from CTRP3 KO and Tg mice. RESULTS: CTRP3 KO mice developed more severe colitis, whereas CTRP3 Tg mice developed less severe colitis than wild-type littermates. The deletion of CTRP3 correlated with decreased levels of Sirtuin-1 (SIRT1), a histone deacetylase, and increased levels of phosphorylated/acetylated NF-κB subunit p65 and proinflammatory cytokines tumor necrosis factor-α and interleukin-6. Results from CTRP3 Tg mice were inverse to those from CTRP3 KO mice. The addition of SIRT1 activator resveratrol to KO intestinal organoids and SIRT1 inhibitor Ex-527 to Tg intestinal organoids suggest that SIRT1 is a downstream effector of CTRP3-related inflammatory changes. In patients with IBD, a similar CTRP3/SIRT1/NF-κB relationship was observed. CONCLUSIONS: CTRP3 expression levels correlate negatively with intestinal inflammation in acute mouse colitis models and patients with IBD. CTRP3 may attenuate intestinal inflammation via SIRT1/NF-κB signaling. The manipulation of CTRP3 signaling, including through the use of SIRT1 activators, may offer translational potential in the treatment of IBD.

The Utility of Leukocyte Esterase Strip Test in the Diagnosis of Pediatric Septic Arthritis.

BACKGROUND: Most tests used to diagnose pediatric septic arthritis are either not accurate or do not produce rapid results. A leukocyte esterase (LE) strip test has previously been validated for the diagnosis of adult native and periprosthetic joint infections. The purpose of this prospective study was to: (1) evaluate the performance characteristics of the LE strip test in the diagnosis of pediatric septic arthritis and (2) determine the false positive rate of LE strip test on the aseptic synovial fluid (SF). METHODS: Between May 2016 and November 2018, SF was obtained from children who were hospitalized at our tertiary referral center on the basis of suspicion of septic arthritis. All patients underwent arthrocentesis, and the aspirate was tested with LE strip test, leukocyte count, and culture. Twenty-five patients satisfied the inclusion criteria. For the second part of the study, SF from 25 children undergoing surgery for developmental dysplasia of the hip was collected and tested with LE strip test, leukocyte count, and culture. RESULTS: In the first part of this study, 19 joints were classified as septic and 6 as aseptic. Considering a positive LE strip test ("++" and "+++" readings) indicative of septic arthritis yielded a sensitivity of 100%, specificity of 83%, positive predictive value of 95%, and negative predictive value of 100%. In the second part, all 25 patients with an aseptic SF had a negative test result ("-" and "+" readings). CONCLUSIONS: The LE strip test seems to be a valuable additional tool in the diagnosis of pediatric septic arthritis. The LE strip test has the advantages of being inexpensive and simple, providing real-time results and having a perfect negative predictive value to rule out the diagnosis of septic arthritis. LEVEL OF EVIDENCE: Level II-diagnostic.