Quorum sensing (QS) is a communication system used by bacteria to coordinate a wide panel of biological functions in a cell density-dependent manner. The Gram-negative Chromobacterium violaceum has previously been shown to use an acyl-homoserine lactone (AHL)-based QS to regulate various behaviors, including the production of proteases, hydrogen cyanide, or antimicrobial compounds such as violacein. By using combined metabolomic and proteomic approaches, we demonstrated that QS modulates the production of antimicrobial and toxic compounds in C. violaceum ATCC 12472. We provided the first evidence of anisomycin antibiotic production by this strain as well as evidence of its regulation by QS and identified new AHLs produced by C. violaceum ATCC 12472. Furthermore, we demonstrated that targeting AHLs with lactonase leads to major QS disruption yielding significant molecular and phenotypic changes. These modifications resulted in drastic changes in social interactions between C. violaceum and a Gram-positive bacterium (Bacillus cereus), a yeast (Saccharomyces cerevisiae), immune cells (murine macrophages), and an animal model (planarian Schmidtea mediterranea). These results underscored that AHL-based QS plays a key role in the capacity of C. violaceum to interact with micro- and macroorganisms and that quorum quenching can affect microbial population dynamics beyond AHL-producing bacteria and Gram-negative bacteria.

PurposeThe aim of the study was to examine patterns of peripapillary andretinal layer damage as a potential marker of neurodegeneration in Parkinson'sdisease (PD) compared to progressive supranuclear palsy (PSP) with 2 SD‐ OCTdevices.MethodsPeripapillary retinal nerve fiber layer (pRNFL), macular thickness (MT)and ganglion cell layer inner plexiform analysis (GCA) by Cirrus and pRNFL analysis and automaticsingle retinal layers macular segmentation by Spectralis were used to evaluate38 patients with PD and 15 patients with PSP.ResultsMean average and superior RNFL by Cirrus were thicker in PD compared to PSP (p = 0.001). The mean central, superior, supero‐temporal and infero‐temporal RNFL thicknesses by Spectralis were also significantly higher in PD compared to PSP (p < 0.05). Using Cirrus OCT, mean MT and all measurements by GCA were significantly higher in PD compared to PSP (p < 0.002). The AUC was larger for minimum GCIPL (0.912) than for average GCIPL thickness (0.850). A minimum GCIPL thickness cut‐off value of 69 μm, was able to differentiate PSP from PD (Sensitivity: 91.7%; Specificity: 72.7%). Minimum and average GCIPL thicknesses significantly correlated with Hoehn and Yahr score (p < 0.05), and with UPDRS (Unified Parkinson's Disease Rating Scale) (p < 0.005).ConclusionsThedifferential diagnosis of Parkinsonian disorders is clinical one and not alwayseasy, especially at the onset of disease. In thecurrent study, the minimum GCIPL thickness was the most sensitiveparameter to differentiate PD from PSP and it was significantly correlated withneurological score. These findings may facilitate the differential diagnosisand give insight into the degenerative processes of atypical parkinsonian syndromes.

Background:The occurrence of uveitis in patients with psoriatic arthritis (PsA) has been documented as the most frequent and important extra-articular manifestation, with an estimated frequency of 7 and 18%. Clinical onset may be acute or insidious, and it may be accompanied by other ocular manifestations. In contrast with spondyloarthropathy related-uveitis, PsA associated tends to be insidious, bilateral, chronic or posterior.Objectives:To describe clinic and immunological features of psoriatic arthritis patients in our centre, especially those with associated-uveitis and to define its frequency.Methods:A retrospective, descriptive and single-centre study (1985-2017) of 494 patients diagnosed with PsA according to the criteria of an expert rheumatologist was conducted. All patients were studied according to a standard protocol. The group was divided into 3 articular categories: pure axial, pure peripheric and mixed. Data regarding enthesitis and dactylitis, as well as HLA-Cw6 and HLA-B27 were extracted, from those available. Ophthalmologic and cutaneous involvement was registered. 216 patients were excluded because of data absence or alternative plausible diagnosis. Descriptive analyses were applied.Results:Eight patients had uveitis (2,9% in this series), only one case developed chronic pattern. Acute anterior uveitis was the form of presentation in 6 patients (75%). Unilateral involvement was registered in 3 (37,5%), in every case with right eye implication. One patient developed up to 13 episodes of acute anterior uveitis, every episode in the same eye. Median of age at first episode was 54 years, 3 (37,5%) patients were female. Regarding articular categories: 1(12,5%) pure axial, 3 (37,5%) pure peripheric and 4 (50%) mixed. Enthesitis was registered in 2 patients, none of our series developed dactylitis. 3 patients (37,5%) were HLA-B27 positive and 2 patients (25%), HLA-Cw6 positive. 6 cases had cutaneous psoriasis (75%). Adalimumab was prescribed to 5 PsA related-uveitis patients with optimal control of disease.Larger PsA cohort without ocular involvement (270 patients), 118 (42,4%) cases were female and median of age was 44 years. Pure axial involvement was present in 20 (7,2%), pure peripheric, 134 (48,2%) and mixed, 122 (43,8%). 31 (11,15%) cases developed enthesis involvement and 18 (6,5%), dactylitis. HLA-B27 was tested positive in 45 patients (19,7%) and HLA-Cw6, in 56 (27,4%). Cutaneous psoriasis was present in 231 cases (83,1%).Conclusion:Frequency of psoriatic arthritis-uveitis is lower in our sample than referred in bibliography. Further investigations are needed to understand the underlying reasons, although it could be related to the use of biologic treatment and narrower inflammatory activity control in comparison to previous studies. No posterior pole involvement, bilaterality, chronicity nor insidious onset are common in our data; neither axial involvement seems to be predictor for the appearance of uveitis.References:[1]Rosenbaum JT. Uveitis in spondyloarthritis including psoriatic arthritis, ankylosing spondylitis, and inflammatory bowel disease. Clin Rheumatol 2015;34:999-1002.[2]Queiro R, et al. Clinical Features and Predictive Factors in Psoriatic Arthritis–Related Uveitis. Semin Arthritis Rheum 2002;31:264-270.[3]Paiva ES, et al. Characterisation of uveitis in patients with psoriatic arthritis. Ann Rheum Dis. 2000;59(1):67–70.Disclosure of Interests:None declared