Lysyl-tRNA synthetase produces diadenosine tetraphosphate to curb STING-dependent inflammation

Inflammation is an essential part of immunity against pathogens and tumors but can promote disease if not tightly regulated. Self and non-self-nucleic acids can trigger inflammation, through recognition by the cyclic GMP-AMP (cGAMP) synthetase (cGAS) and subsequent activation of the stimulator of interferon genes (STING) protein. Here, we show that RNA:DNA hybrids can be detected by cGAS and that the Lysyl-tRNA synthetase (LysRS) inhibits STING activation through two complementary mechanisms. First, LysRS interacts with RNA:DNA hybrids, delaying recognition by cGAS and impeding cGAMP production. Second, RNA:DNA hybrids stimulate LysRS-dependent production of diadenosine tetraphosphate (Ap4A) that in turn attenuates STING-dependent signaling. We propose a model whereby these mechanisms cooperate to buffer STING activation. Consequently, modulation of the LysRS-Ap4A axis in vitro or in vivo interferes with inflammatory responses. Thus, altogether, we establish LysRS and Ap4A as pharmacological targets to control STING signaling and treat inflammatory diseases.

The patient's view on rare disease trial design - a qualitative study

Background

Clinical trials in rare diseases are more challenging than trials in frequent diseases. Small numbers of eligible trial participants, often complicated by heterogeneity among rare disease patients, hamper the design and conduct of a ‘classical’ Randomized Controlled Trial. Therefore, novel designs are developed by statisticians. However, it is important to be aware of possible design aspects that may jeopardize the feasibility of trial conduct. If the burden of participation is considered out of proportion by patients or parents, recruitment may fail or participants may drop out before trial completion. In order to maximize the chance of success of trials in small populations, it is important to know which aspects of trial design are considered important by patients.

Results

We have interviewed all ten members of the Patient Think Tank (PTT) of the ASTERIX project, a European research consortium on methodology for clinical trials in small populations. The PTT members are rare disease patient representatives who have completed extensive training in clinical trial methodology. We have analyzed the interviews qualitatively according to Grounded Theory using a thematic analysis, and we structured the topics in four chronologically ordered themes: 1. Involvement in trial design; 2. Opinions on trial design; 3. Trial participation; 4. Phase after the trial. Our main findings are that the PTT-members recommend that patients are involved in trial design from an early stage on, and have influence on the outcomes and measurement instruments that are chosen in the trial, the length of the study, the choice of participants, and the information that is sent to potential participants. Also, according to the PTT-members, patient groups should consider setting up disease registries, placebo groups should be minimized, and more education on clinical trials is advised.

Conclusions

Rare disease patient representatives who have been educated about clinical trial methodology think it is important to involve patient representatives in research at an early stage. They can be of advice in trial design in such a way that the ratio of potential benefit and burden of trial participation as well as the chosen outcome measures and in- and exclusion criteria are optimized.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1002-z) contains supplementary material, which is available to authorized users.

Microprocessor Control of the Spraying of Graded Coatings

A systematic study was made of the characteristics of a microprocessor controlled powder feeder in view of its utilization for the deposition of graded coating. The unit tested had the capability of feeding three different powders at rates which could be continuously varied up to about 40 g/min. MgOZrO2. was deposited on a stainless steel substrate using a series of thin (Ni/Cr)-Zirconia coats as intermediate layers. The results showed that such a technique could provide a valuable means of achieving a precise and effective control on the composition of the intermediate layers which can have important effects on the final quality of the deposit.

Histopathological analysis in experimental macular surgery with trypan blue

AIM

To analyse the effect of trypan blue on the retina in an experimental setting of macular surgery.

METHODS

Porcine eyes were used within 3 hours after death. The eyes were hemisected and the vitreous removed. Trypan blue (0.15%) was applied over the trephined posterior pole, whereas the rest of the eye cup was filled with a balanced salt solution (BSS). The dye and the BSS were removed after 1 minute and the complete eye cup irrigated and filled with fresh BSS. Both the treated and untreated retinas were illuminated with a standard surgical light pipe and source at maximum power for 10 minutes. Both the trypan blue exposed retina and the non-treated surrounding retina were processed for histology.

RESULTS

Exposure of the retina to trypan blue for 1 minute, followed by illumination caused no histologically detectable damage compared to the controls. No microarchitectural disorganisation, cellular disruption, or affection of the vitreoretinal interface was detected.

CONCLUSIONS

These findings indicate that a 1 minute exposure of trypan blue followed by illumination does not cause an acute morphologically detectable toxic effect on the porcine retina.

[The role of electrooculographic examinations in the glaucoma diagnosis]

PURPOSE

To evaluate the significance of the electrooculography in the diagnosis of glaucoma.

MATERIAL AND METHODS

We studied 31 patients with primary open-angle glaucoma (aged 22-69 years), 29 patients with normal-tension glaucoma (aged 19-77 years) and 22 healthy controls (aged 38-65 years). We performed routine ophthalmological examinations and electrooculography in all patients.

RESULTS

Arden's coefficient results concerning electrooculography were the highest in control group and the lowest in primary open-angle glaucoma group, but the differences were not statistically significant.

CONCLUSION

Electrooculographic examinations do not seem to be effective for detecting glaucoma.

Pattern of respiration in patients recovering from barbiturate overdose

Ventilation has been recorded in seven patients who were unconscious following self-poisoning. Measurements were obtained on admission to the hospital and repeated daily until the patients regained consciousness. On admission, recordings were characterized by a low minute ventilation as a result of a low tidal volume in spite of a high frequency of respiration. During the period of recovery tidal volume and minute ventilation increased, whereas frequency decreased. The modifications observed during recovery were the reverse of those noted during the induction of anaesthesia wih barbiturates in man. However, these modifications differ from those observed during induction of anaesthesia in cats. Consequently, as far as respiratory control is concerned, models elaborated in animals cannot be extrapolated to deeply anaesthetized human subjects.