In silico agent-based modeling approach to characterize multiple in vitro tuberculosis infection models

In vitro models of Mycobacterium tuberculosis (Mtb) infection are a valuable tool for examining host-pathogen interactions and screening drugs. With the development of more complex in vitro models, there is a need for tools to help analyze and integrate data from these models. To this end, we introduce an agent-based model (ABM) representation of the interactions between immune cells and bacteria in an in vitro setting. This in silico model was used to simulate both traditional and spheroid cell culture models by changing the movement rules and initial spatial layout of the cells in accordance with the respective in vitro models. The traditional and spheroid simulations were calibrated to published experimental data in a paired manner, by using the same parameters in both simulations. Within the calibrated simulations, heterogeneous outputs are seen for bacterial count and T cell infiltration into the macrophage core of the spheroid. The simulations also predict that equivalent numbers of activated macrophages do not necessarily result in similar bacterial reductions; that host immune responses can control bacterial growth in both spheroid structure dependent and independent manners; that STAT1 activation is the limiting step in macrophage activation in spheroids; and that drug screening and macrophage activation studies could have different outcomes depending on the in vitro culture used. Future model iterations will be guided by the limitations of the current model, specifically which parts of the output space were harder to reach. This ABM can be used to represent more in vitro Mtb infection models due to its flexible structure, thereby accelerating in vitro discoveries.

A clinician-run 3D-printing laboratory for orthopaedic preoperative planning: an illustrative case series

BACKGROUND: Orthopaedic surgery often benefits from innovation in biomedical engineering, with 3D printing being one of the latest examples. Proving cost-effectiveness and improved clinical outcomes remains challenging. Because of the reduced cost and increased accessibility, it has been possible to start an orthopaedic 3D-printing laboratory in a South African tertiary hospital, exploring the place for this emergent technology in orthopaedic practice. This case series aims to illustrate the clinical use of 3D-printed anatomical models and investigate the time and cost involved in their manufacture METHODS: The design and manufacturing process is discussed, and a retrospective descriptive case series is presented of all models manufactured from January 2020 to April 2021. Using three illustrative cases, we elaborate on two main usage situations: intraoperative reference models (haptic maps) or rehearsal and templating (simulation models RESULTS: In the study, 3D-printed anatomical models were manufactured for 16 patients. For 12 patients, these were simulation models, and for the other four patients, haptic maps were made. The mean time for manufacture was 33 hours (range 8-62), and the median cost per patient was ZAR 3 257.62 (range ZAR 927.17 to ZAR 7 177.09 CONCLUSION: Considering the decreasing cost and ease of using 3D-printing technology, starting a clinician-run orthopaedic 3D-printing laboratory at a South African training hospital has become possible. In this series we illustrate how 3D printing has been used at our unit for planning and rehearsal of a wide range of orthopaedic cases, and we establish a baseline of time and cost expenditure. The cost-effectiveness of implementing 3D-printing technology in everyday orthopaedic practice warrants further investigation Level of evidence: Level 5

Human Monocytic Suppressive Cells Promote Replication of Mycobacterium tuberculosis and Alter Stability of in vitro Generated Granulomas

Tuberculosis (TB) has tremendous public health relevance. It most frequently affects the lung and is characterized by the development of unique tissue lesions, termed granulomas. These lesions encompass various immune populations, with macrophages being most extensively investigated. Myeloid derived suppressor cells (MDSCs) have been recently identified in TB patients, both in the circulation and at the site of infection, however their interactions with Mycobacterium tuberculosis (Mtb) and their impact on granulomas remain undefined. We generated human monocytic MDSCs and observed that their suppressive capacities are retained upon Mtb infection. We employed an in vitro granuloma model, which mimics human TB lesions to some extent, with the aim of analyzing the roles of MDSCs within granulomas. MDSCs altered the structure of and affected bacterial containment within granuloma-like structures. These effects were partly controlled through highly abundant secreted IL-10. Compared to macrophages, MDSCs activated primarily the NF-κB and MAPK pathways and the latter largely contributed to the release of IL-10 and replication of bacteria within in vitro generated granulomas. Moreover, MDSCs upregulated PD-L1 and suppressed proliferation of lymphocytes, albeit with negligible effects on Mtb replication. Further comprehensive characterization of MDSCs in TB will contribute to a better understanding of disease pathogenesis and facilitate the design of novel immune-based interventions for this deadly infection.

Spectrum of autoantibodies for gastrointestinal autoimmune diseases in systemic lupus erythematosus patients

Background

Organ-specific autoimmune diseases may appear in patients with systemic lupus erythematosus (SLE). Gastrointestinal symptoms are well documented in SLE and may be similar to those related to autoimmune gastrointestinal diseases.

Objective

Our aim was to search for gastrointestinal organ-specific autoantibodies in 194 patients with systemic lupus and 103 healthy controls from Southern Brazil.

Methods

Anti-endomysium antibodies (IgA-EmA), anti-gastric parietal cells (GPC) antibodies, anti-smooth muscle antibodies (ASMA), anti-mitochondrial antibodies (AMA) and anti-LKM-1 (liver-kidney microsomal) were searched for using indirect immunofluorescence in the sera of patients and controls.

Results

The total positivity of antibodies in SLE patients was 14.4% (28/194) and differed significantly from healthy individuals (0.97%; p < 0.001). IgA-EmA was more common in lupus patients than in controls (11/194; p = 0.009), and one of these patients had dermatitis herpetiformis. Clinical association revealed that IgA-EmA was more common in SLE patients with discoid lesions. The frequency of anti-GPC ( p = 0.10), ASMA ( p = 0.16) and AMA ( p = 0.55) did not differ significantly between groups. No patient presented LKM-1 autoantibodies. One patient presenting anti-GPC was diagnosed with atrophic gastritis and pernicious anemia.

Conclusion

Only IgA-EmA was significantly associated with lupus and with the presence of discoid lesions. Until now, no obvious association with celiac disease has been found.