Guidelines for visualization and analysis of DC in tissues using multiparameter fluorescence microscopy imaging methods

This article is part of the Dendritic Cell Guidelines article series, which provides a collection of state-of-the-art protocols for the preparation, phenotype analysis by flow cytometry, generation, fluorescence microscopy, and functional characterization of mouse and human dendritic cells (DC) from lymphoid organs and various non-lymphoid tissues. Here, we provide detailed procedures for a variety of multiparameter fluorescence microscopy imaging methods to explore the spatial organization of DC in tissues and to dissect how DC migrate, communicate, and mediate their multiple functional roles in immunity in a variety of tissue settings. The protocols presented here entail approaches to study DC dynamics and T cell cross-talk by intravital microscopy, large-scale visualization, identification, and quantitative analysis of DC subsets and their functions by multiparameter fluorescence microscopy of fixed tissue sections, and an approach to study DC interactions with tissue cells in a 3D cell culture model. While all protocols were written by experienced scientists who routinely use them in their work, this article was also peer-reviewed by leading experts and approved by all co-authors, making it an essential resource for basic and clinical DC immunologists.

Antimicrobial efficacy and inactivation kinetics of a novel LED based UV-irradiation technology

BACKGROUND

UV light emitting diodes (UV-LEDs) are energy efficient and of special interest for the inactivation of microorganisms. In context of the current pandemic, novel UV technologies can offer a powerful alternative of effective infection prevention and control (IPC).

METHODS

We here assessed the antimicrobial efficacy of UV-C LEDs on Escherichia coli, Pseudomonas fluorescens and Listeria innocua as well as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), human immunodeficiency virus 1 (HIV-1) and murine norovirus (MNV) dried on inanimate surfaces based on the European standard EN 17272.

RESULTS

We found an inactivation rate of 90% for the tested bacteria at a mean UV-C dose, averaged over all three investigated UV-C wavelengths, of 1.7 mJ cm^-2 for E. coli, 1.9 mJ cm^-2 for P. fluorescens and 1.5 mJ cm^-2 for L. innocua. For the tested viruses, a 90% inactivation rate at UV doses less than 15 mJ cm^-2 for applied UV wavelengths at 255 nm and 265 nm were found. Exposure of viruses to longer UV wavelengths such as 275 nm and 285 nm, required much higher doses up to 120 mJ cm^-2 for inactivation. Regarding inactivation, non-enveloped MNV required much higher UV doses for all tested wavelengths compared to SARS-CoV-2 or HIV-1.

CONCLUSION

Overall, our data recommend the use of LEDs emitting at shorter wavelengths of the UV-C spectrum to inactivate bacteria as well as enveloped and non-enveloped viruses by exposure to the appropriate UV-dose. However, low availability and excessive production costs of shortwave UV-C LEDs restricts the implementation currently and supports the use of longwave UV-C LEDs in combination with higher irradiation doses.

HIV-1 Trans Infection via TNTs Is Impeded by Targeting C5aR

Nonadjacent immune cells communicate through a complex network of tunneling nanotubes (TNTs). TNTs can be hijacked by HIV-1, allowing it to spread between connected cells. Dendritic cells (DCs) are among the first cells to encounter HIV-1 at mucosal sites, but they are usually efficiently infected only at low levels. However, HIV-1 was demonstrated to productively infect DCs when the virus was complement-opsonized (HIV-C). Such HIV-C-exposed DCs mediated an improved antiviral and T-cell stimulatory capacity. The role of TNTs in combination with complement in enhancing DC infection with HIV-C remains to be addressed. To this aim, we evaluated TNT formation on the surface of DCs or DC/CD4+ T-cell co-cultures incubated with non- or complement-opsonized HIV-1 (HIV, HIV-C) and the role of TNTs or locally produced complement in the infection process using either two different TNT or anaphylatoxin receptor antagonists. We found that HIV-C significantly increased the formation of TNTs between DCs or DC/CD4+ T-cell co-cultures compared to HIV-exposed DCs or co-cultures. While augmented TNT formation in DCs promoted productive infection, as was previously observed, a significant reduction in productive infection was observed in DC/CD4+ T-cell co-cultures, indicating antiviral activity in this setting. As expected, TNT inhibitors significantly decreased infection of HIV-C-loaded-DCs as well as HIV- and HIV-C-infected-DC/CD4+ T-cell co-cultures. Moreover, antagonizing C5aR significantly inhibited TNT formation in DCs as well as DC/CD4+ T-cell co-cultures and lowered the already decreased productive infection in co-cultures. Thus, local complement mobilization via DC stimulation of complement receptors plays a pivotal role in TNT formation, and our findings herein might offer an exciting opportunity for novel therapeutic approaches to inhibit trans infection via C5aR targeting.

Advances in Rheological Analysis of Injection Molding

Finite element methods offer the potential to greatly refine mold filling analysis. As a consequence, there is strong pressure to apply this technology on a routine basis in industry. Unfortunately, traditional finite element techniques are not adequate to design a viable model of the flow of molten plastic into a mold. This paper explains the mathematical problems that must be solved. It describes why the widely used classical matrix techniques give erratic results, and demonstrates that it is mandatory to apply a total dynamic analysis to obtain a reliable mold filling simulation. A new technique is introduced to solve the problems caused by non-linear material properties and moving boundaries.

Treatment of sialorrhoea with ultrasound guided botulinum toxin type A injection in patients with neurological disorders

OBJECTIVES

To investigate the safety and efficacy of ultrasound guided botulinum toxin type A (BTX-A) injections into salivary glands for the treatment of sialorrhoea in patients with neurological disorders.

METHODS

The parotid and submandibular glands of 10 patients were injected with BTX-A using ultrasound guidance. Before injection, the baseline rate of salivation was assessed using a visual analogue scale. Postinjection, assessments were repeated at regular intervals for up to 1 year.

RESULTS

Of the 10 patients treated, nine (90%) reported a subjective reduction in salivation post-treatment and one patient (10%) found no improvement. Visual analogue scale scores showed a reduction of 55% in the mean rate of salivation for all patients and a reduction of 60.8% for the group of responders. No serious adverse events occurred and no procedure related complications were reported.

CONCLUSIONS

This is the first study to report (1) the injection of BTX-A (BOTOX) into both parotid and submandibular glands, and (2) the use of ultrasound guidance during the administration of BTX-A into salivary glands. The results suggest that the technique is safe and that BTX-A injections are effective for the treatment of sialorrhoea in patients with neurological disorders.