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Beta(2)-microglobulin (beta(2)m) forms amyloid fibrils that deposit in the musculo-skeletal system in patients undergoing long-term hemodialysis. How beta(2)m self-assembles in vivo is not understood, since the monomeric wild-type protein is incapable of forming fibrils in isolation in vitro at neutral pH, while elongation of fibril-seeds made from recombinant protein has only been achieved at low pH or at neutral pH in the presence of detergents or cosolvents. Here we describe a systematic study of the effect of 11 physiologically relevant factors on beta(2)m fibrillogenesis at pH 7.0 without denaturants. By comparing the results obtained for the wild-type protein with those of two variants (DeltaN6 and V37A), the role of protein stability in fibrillogenesis is explored. We show that DeltaN6 forms low yields of amyloid-like fibrils at pH 7.0 in the absence of seeds, suggesting that this species could initiate fibrillogenesis in vivo. By contrast, high yields of amyloid-like fibrils are observed for all proteins when assembly is seeded with fibril-seeds formed from recombinant protein at pH 2.5 stabilized by the addition of heparin, serum amyloid P component (SAP), apolipoprotein E (apoE), uremic serum, or synovial fluid. The results suggest that the conditions within the synovium facilitate fibrillogenesis of beta(2)m and show that different physiological factors may act synergistically to promote fibril formation. By comparing the behavior of wild-type beta(2)m with that of DeltaN6 and V37A, we show that the physiologically relevant factors enhance fibrillogenesis by stabilizing fibril-seeds, thereby allowing fibril extension by rare assembly competent species formed by local unfolding of native monomers.

The protein beta(2)-microglobulin (beta(2)m) aggregates to form classical amyloid fibrils in patients undergoing long-term haemodialysis. Amyloid-like fibrils with a cross-beta fold can also be formed from wild-type beta(2)m under acidic conditions in vitro. The morphology of such fibrils depends critically on the conditions used: incubation of beta(2)m in low ionic strength buffers at pH 2.5 results in the formation of long (microm), straight fibrils while, at pH 3.6, short (<500 nm) fibrils form. At higher ionic strengths (0.2-0.4 M) at pH 1.5-3.6, the fibrils have a distinct curved and nodular morphology. To determine the conformational properties of beta(2)m within in vitro fibrils of different morphologies, limited proteolysis of each fibril type using pepsin was performed and the resulting peptide fragments identified by tandem mass spectrometry. For comparison, the proteolytic degradation patterns of monomeric beta(2)m and seven synthetic peptides spanning the entire sequence of the intact protein were similarly analysed. The results show that fibrils with different morphologies result in distinct digestion patterns. While the curved, worm-like fibrils are relatively weakly protected from proteolysis, the long, straight fibrils formed at pH 2.5 at low ionic strength show only a single cut-site at Val9, demonstrating that substantial refolding of the initially acid-denatured and unprotected state of beta(2)m occurs during assembly. The data demonstrate that the organisation of the polypeptide chain in fibrils with different morphological features differs considerably, despite the fact that the fibrils possess a common cross-beta architecture.

The atomic force microscope (AFM) is a versatile instrument that can be used to image biological samples at nanometre resolution as well as to measure inter and intra-molecular forces in air and liquid environments. This review summarises the use of AFM applied to protein and peptide self-assembly systems involved in amyloid formation. The technical principles of the AFM are outlined and its advantages and disadvantages are highlighted and discussed in the context of the rapidly developing field of amyloid research.

To investigate Th17 cells in the setting of acute kidney injury (AKI), the master regulator of Th17 cell differentiation, RORγT, was mutated in Lewis rats using CRISPR/Cas9 technology. In response to 40 min bilateral renal I/R, Rorc-/- rats were resistant to injury relative to wild-type Rorc+/+ rats. This protection was associated with inhibition of IL17 expression and reduced infiltration of CD4+ cells, CD8+ cells, B-cells and macrophages. To evaluate the effect of Th17 cells on repair, ischemia was increased to 50 min in Rorc-/- rats. This maneuver equalized the initial level of injury in Rorc-/- and Rorc+/+ rats 1 to 2 days post I/R based on serum creatinine values. However Rorc-/- rats, but not Rorc+/+ rats, failed to successfully recover renal function and had high mortality by 4 days post I/R. Kidney tubules from Rorc+/+ rats showed evidence of repair by day-4 post I/R, while Rorc-/- rats showed persistent necrosis and elevated cell proliferation. Adoptive transfer of CD4+ cells from spleen of Rorc+/+ rats or supplementation of exogenous rIL17 by osmotic mini-pump improved renal function and survival of Rorc-/- rats following 50 min of I/R. This was associated with a relative decrease in the number of M1-type macrophages and a relative increase in the percentage of T-regulatory cells. Taken together, these data suggest Th17 cells have both a deleterious and beneficial role in kidney injury and recovery, contributing to early post-ischemic injury and inflammation but may also be critical in resolution of inflammation during kidney repair.

Introduction. Oral tissues are generally homeostatic despite exposure to many potential inflammatory agents including the resident microbiota. This requires the balancing of inflammation by regulatory mechanisms and/or anti-inflammatory commensal bacteria. Thus, the levels of anti-inflammatory commensal bacteria in resident populations may be critical in maintaining this homeostatic balance. Hypothesis/Gap Statement. The incidence of immunosuppressive streptococci in the oral cavity is not well established. Determining the proportion of these organisms and the mechanisms involved may help to understand host-microbe homeostasis and inform development of probiotics or prebiotics in the maintenance of oral health. Aim. To determine the incidence and potential modes of action of immunosuppressive capacity in resident oral streptococci. Methodology. Supragingival plaque was collected from five healthy participants and supragingival and subgingival plaque from five with gingivitis. Twenty streptococci from each sample were co-cultured with epithelial cells±flagellin or LL-37. CXCL8 secretion was detected by ELISA, induction of cytotoxicity in human epithelial cells by lactate dehydrogenase release and NFκB-activation using a reporter cell line. Bacterial identification was achieved through partial 16S rRNA gene sequencing and next-generation sequencing. Results. CXCL8 secretion was inhibited by 94/300 isolates. Immunosuppressive isolates were detected in supragingival plaque from healthy (4/5) and gingivitis (4/5) samples, and in 2/5 subgingival (gingivitis) plaque samples. Most were Streptococcus mitis/oralis. Seventeen representative immunosuppressive isolates all inhibited NFκB activation. The immunosuppressive mechanism was strain specific, often mediated by ultra-violet light-labile factors, whilst bacterial viability was essential in certain species. Conclusion. Many streptococci isolated from plaque suppressed epithelial cell CXCL8 secretion, via inhibition of NFκB. This phenomenon may play an important role in oral host-microbe homeostasis.

Context: Professional commitment, or one's affinity and loyalty to a career, has become a topic of interest in athletic training. The expanding research on the topic, however, has omitted newly credentialed athletic trainers (ATs). For an impressionable group of practitioners, transitioning to clinical practice can be stressful.Objective: To explore the professional commitment of newly credentialed ATs in the secondary school setting.Setting: Secondary school. Design: Qualitative study. Patients or Other Participants: A total of 31 newly credentialed ATs (6 men, 25 women; mean age ¼ 24 6 3 years) participated. Of these, 17 ATs (4 men, 13 women; mean age ¼ 25 6 4 years) were employed full time in the secondary school setting, and 14 ATs (2 men, 12 women; mean age ¼ 23.0 6 2.0 years) were graduate assistant students in the secondary school setting.Data Collection and Analysis: All participants completed semistructured interviews, which focused on their experiences in the secondary school setting and transitioning into the role and setting. Transcripts were analyzed using the phenomenologic approach. Creditability was established by peer review, member checks, and researcher triangulation.Results: Four main findings related to the professional commitment of newly credentialed ATs in the secondary school setting were identified. Work-life balance, professional relationships formed with the student-athletes, enjoyment gained from working in the secondary school setting, and professional responsibility emerged as factors facilitating commitment.Conclusions: Affective commitment is a primary facilitator of professional commitment. Newly credentialed ATs who enjoy their jobs and have time to engage in nonwork roles are able to maintain a positive professional commitment. Our findings align with the previous literature and help strengthen our understanding that rejuvenation and passion are important to professional commitment.Key Words: work-life balance, work roles, transition to clinical practice Key PointsWork-life balance is an important facilitator of professional commitment for the athletic trainer in the secondary school setting. Positive workplace relationships can help the secondary school athletic trainer to maintain professional commitment.

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