Objective: To reveal the cause of the impaired elimination of Salmonella enteritidis in HLA–B27–transfected human monocytic cells and to study whether the B pocket of HLA–B27 contributes to these modulatory effects.Methods: Stable U937 cell transfectants expressing HLA–A2, B27, or different forms of B27 with amino acid substitutions in the B pocket were prepared. Mock‐transfected cells were prepared using the antibiotic resistance vector (pSV2neo) alone. Cells were differentiated, infected with S enteritidis, and the number of live intracellular S enteritidis organisms was determined using the colony‐forming unit method. To visualize intracellular S enteritidis, the bacteria were transformed with green fluorescent protein (GFP), and studied by confocal microscopy.Results: Cells expressing wild‐type HLA–B27 were more permissive of intracellular replication of S enteritidis compared with mock‐transfected or A2‐transfected controls. Cells expressing B27 with an altered B pocket composition having either 6 amino acid substitutions (B27.A2B; substitutions H9F, T24A, E45M, I66K, C67V, and K70H) or a single substitution (B27.E45M) were no longer permissive of S enteritidis replication. In contrast, cells expressing B27 with the single substitution of F for H at position 9 (B27.H9F) retained their permissiveness. Studies using GFP‐transformed S enteritidis confirmed that the increase in the amount of intracellular bacteria in B27‐expressing cells was due to replication of the bacteria.Conclusion: Our data indicate that HLA–B27 expression modulates the host–microbe interaction that results in an impaired capacity of monocytes to resist intracellular replication of S enteritidis. The phenotype is dependent on glutamic acid at position 45 in the B pocket and, thus, may be due to properties of the B27 heavy chain that are related to this residue. The ability of HLA–B27 to confer susceptibility to Salmonella‐triggered reactive arthritis may occur, at least in part, through these modulatory effects.

Background: Species of the tick-transmitted spirochete groupBorrelia burgdorferisensu lato (B. burgdorferi) cause Lyme borreliosis. Acute borrelial infection of the skin has unusual characteristics with only a mild local inflammatory response suggesting that the interaction between borreliae and the cells of the first-line defence might differ from that of other bacteria. It has been reported that human neutrophils phagocytose motile borreliae through an unconventional mechanism (tube phagocytosis) which is not observed with non-motile borreliae. Therefore, it would be of great interest to visualise the bacteria by a method not affecting motility and viability of borreliae to be able to study their interaction with the cells of the innate immunity. Carboxyfluorescein diacetate, succinimidyl ester (CFSE) labelling has been previously used for studying the adhesion of labelled bacteria to host cells and the uptake of labelled substrates by various cells using flow cytometry.Results: In this study, CFSE was shown to efficiently stain different genospecies ofB. burgdorferiwithout affecting bacterial viability or motility. Use of CFSE staining allowed subsequent quantification of borreliae associated with human neutrophils with flow cytometry and confocal microscopy. As a result, no difference in association between different borrelial genospecies (Borrelia burgdorferisensu stricto,Borrelia afzelii,Borrelia garinii), or between borreliae and the pyogenic bacteriumStreptococcus pyogenes, with neutrophils could be detected. Borrelial virulence, on the other hand, affected association with neutrophils, with significantly higher association of a non-virulent mutantB. burgdorferisensu stricto strain compared to the parental virulent wild type strain.Conclusion: These results suggest that the flow cytometric assay using CFSE labelled borreliae is a valuable tool in the analysis of the interaction between borreliae and human neutrophils. The results also indicate a clear difference in the association with neutrophils between virulent and non-virulent borrelial strains.

Background: Burnout is an undesirable mental condition, which may have a negative impact on individuals’ health and work ability. This study aimed to evaluate the relationship between diet and burnout symptoms among female public sector employees. Methods: A cross-sectional study was conducted in 2015 among 630 female employees from 10 municipal work units of the city of Pori, Finland. Burnout symptoms were assessed with the Bergen Burnout Indicator (BBI). The consumption of food items was determined using the food frequency questionnaire (FFQ). The main food groups were categorized into healthy and unhealthy foods based on the Nordic Nutrition Recommendations for a healthy and balanced diet. Results: In multivariate linear regression analysis, consumption of healthy food items had an inverse relationship with the severity of burnout symptoms independently of age, education years, physical activity, and depressive symptoms. De-tailed analysis revealed that subjects with lower BBI score consumed more often low-fat dairy produce, vegetables, fruit and berries, vegetable food, and white meat. Conclusions: Frequent consumption of healthy food items is associated with low level of burnout symptoms. Our results emphasize the importance of diverse and balanced healthy diet to promote work well-being.

Objective To study whether HLA–B27 modifies some key factors controlling inflammatory responses on lipopolysaccharide (LPS) stimulation in human monocytic cells. Methods U937 human monocytic cells were stably transfected with either HLA–B27 genomic DNA, HLA–B27 complementary DNA, HLA–A2 genomic DNA, or with the resistant vector pSV2neo (mock) alone. The cells were stimulated with LPS. Electrophoretic mobility shift assay was performed to determine nuclear factor κB (NF-κB) and heat-shock factor 1 activities, Western blotting was performed to detect the expressions of inhibitory κBα (IκBα) and heat-shock proteins (HSPs), and enzyme-linked immunosorbent assay was performed to measure tumor necrosis factor α (TNFα) secretion. Results The expression of HLA–B27 modulated the response to LPS in U937 human monocytic cells. Stimulation with LPS led to faster degradation of IκBα regulatory proteins, accompanied by faster and prolonged activation of NF-κB in HLA–B27–expressing cells compared with HLA–A2 and mock transfectants. The secretion of TNFα upon LPS stimulation correlated well with the activation of NF-κB. No activation of the heat-shock response was observed. Conclusion Our data indicate that HLA–B27 has effects on host responses to LPS that are unrelated to antigen presentation. Two crucial events in the development of arthritis, the activation of NF-κB and the secretion of TNFα, were found to be enhanced in HLA–B27–expressing cells upon LPS stimulation. Because LPS is known to be present in the inflamed joints of patients with reactive arthritis (ReA), the enhanced inflammatory response of HLA–B27–positive cells upon LPS stimulation offers an attractive explanation for the role of HLA–B27 in the development of ReA.

Spondyloarthropathies (SpA) are a group of chronic rheumatic diseases, which show a strong asoociation with human leukocyte antigen (HLA)-B27. Although the association between HLAB27 and the susceptibility to SpA was discovered thirty years ago, the exact mechanism by which HLA-B27 predisposes to disease development remains unclear. The classical role of MHC class I molecules is to present peptides for CD8+ T cells. Therefore, it has been proposed that the antigen presenting function of HLA-B27 is somehow altered in the patients developing SpA. However, despite extensive research, the attempts to create a comprehensive theory that would explain the role of HLA-B27 as an antigen presenting molecule in the development of SpA have been unsuccessful. Reactive arthritis (ReA) belongs to the group of SpA. It is a joint inflammation developing after certain bacterial infections e.g. Salmonella, Yersinia, and Chlamydia. Several unrelated observations indicate that HLA-B27 modulates the interaction between ReA-triggering bacteria and host cell. These findings suggest that HLA-B27 may possess functions, which are unrelated to antigen presentation. In this paper, we summarize these findings and discuss their potential impact in the development of SpA.