Aberrant Lipid Metabolism in Macrophages Is Associated with Granuloma Formation in Sarcoidosis

Rationale: Chronic sarcoidosis is a complex granulomatous disease with limited treatment options that can progress over time. Understanding the molecular pathways contributing to disease would aid in new therapeutic development. Objectives: To understand whether macrophages from patients with nonresolving chronic sarcoidosis are predisposed to macrophage aggregation and granuloma formation and whether modulation of the underlying molecular pathways influence sarcoidosis granuloma formation. Methods: Macrophages were cultivated in vitro from isolated peripheral blood CD14+ monocytes and evaluated for spontaneous aggregation. Transcriptomics analyses and phenotypic and drug inhibitory experiments were performed on these monocyte-derived macrophages. Human skin biopsies from patients with sarcoidosis and a myeloid Tsc2-specific sarcoidosis mouse model were analyzed for validatory experiments. Measurements and Main Results: Monocyte-derived macrophages from patients with chronic sarcoidosis spontaneously formed extensive granulomas in vitro compared with healthy control participants. Transcriptomic analyses separated healthy and sarcoidosis macrophages and identified an enrichment in lipid metabolic processes. In vitro patient granulomas, sarcoidosis mouse model granulomas, and those directly analyzed from lesional patient skin expressed an aberrant lipid metabolism profile and contained increased neutral lipids. Conversely, a combination of statins and cholesterol-reducing agents reduced granuloma formation both in vitro and in vivo in a sarcoidosis mouse model. Conclusions: Together, our findings show that altered lipid metabolism in sarcoidosis macrophages is associated with its predisposition to granuloma formation and suggest cholesterol-reducing therapies as a treatment option in patients.

Efficacy and safety of mTOR inhibition in cutaneous sarcoidosis: a single-centre trial

BACKGROUND

Sarcoidosis is an inflammatory condition that can affect various organs and tissues, causing the formation of granulomas and subsequent functional impairment. The origin of sarcoidosis remains unknown and there are few treatment options. Mechanistic target of rapamycin (mTOR) activation is commonly seen in granulomas of patients across different tissues and has been shown to induce sarcoidosis-like granulomas in a mouse model. This study aimed to examine the efficacy and safety of the mTOR inhibitor sirolimus as a treatment for cutaneous sarcoidosis.

METHODS

We did a single-centre, randomised study treating patients with persistent and glucocorticoid-refractory cutaneous sarcoidosis with sirolimus at the Vienna General Hospital, Medical University of Vienna (Vienna, Austria). We recruited participants who had persistent, active, and histologically proven cutaneous sarcoidosis. We used an n-of-1 crossover design in a placebo-controlled, double-blind topical treatment period and a subsequent single-arm systemic treatment phase for 4 months in the same participants. Participants initially received either 0·1% topical sirolimus in Vaseline or placebo (Vaseline alone), twice daily. After a washout period, all participants were subsequently administered a 6 mg loading dose followed by 2 mg sirolimus solution orally once daily, aiming to achieve serum concentrations of 6 ng/mL. The primary endpoint was change in the Cutaneous Sarcoidosis Activity and Morphology Index (CSAMI) after topical or systemic treatment. All participants were included in the safety analyses, and patients having completed the respective treatment period (topical treatment or systemic treatment) were included in the primary analyses. Adverse events were assessed at each study visit by clinicians and were categorised according to their correlation with the study drug, severity, seriousness, and expectedness. This study is registered with EudraCT (2017-004930-27) and is now closed.

FINDINGS

16 participants with persistent cutaneous sarcoidosis were enrolled in the study between Sept 3, 2019, and June 15, 2021. Six (37%) of 16 participants were men, ten (63%) were women, and 15 (94%) were White. The median age of participants was 54 years (IQR 48-58). 14 participants were randomly assigned in the topical phase and 2 entered the systemic treatment phase directly. Daily topical treatment did not improve cutaneous lesions (effect estimate -1·213 [95% CI -2·505 to 0·079], p=0·066). Systemic treatment targeting trough serum concentrations of 6 ng/mL resulted in clinical and histological improvement of skin lesions in seven (70%) of ten participants (median -7·0 [95% CI -16·5 to -3·0], p=0·018). Various morphologies of cutaneous sarcoidosis, including papular, nodular, plaque, scar, and tattoo-associated sarcoidosis, responded to systemic sirolimus therapy with a long-lasting effect for more than 1 year after treatment had been stopped. There were no serious adverse events and no deaths.

INTERPRETATION

Short-term treatment with systemic sirolimus might be an effective and safe treatment option for patients with persistent glucocorticoid-refractory sarcoidosis with a long-lasting disease-modulating effect. The effect of sirolimus in granulomatous inflammation should be investigated further in large, multi-centre, randomised clinical trials.

FUNDING

Vienna Science and Technology Fund, Austrian Science Fund.

[Assessment of validity of the German version of the Manchester Triage System]

BACKGROUND

The Manchester Triage System (MTS) was first introduced in 1996. Since then, the original English MTS version has undergone multiple evaluations of its validity and reliability. Due to translation and differing algorithms, only contradictory data regarding accuracy are available for the German MTS version. The aim of this study was to assess the validity of the current German version of the MTS in a retrospective observational setting.

MATERIALS AND METHODS

All surgical and medical patients presenting at the emergency department of an Austrian regional hospital between 1 and 30 July 2020 were included in this study. Data of vital parameters at the time of triage, overall hospitalisation rate, length of hospitalisation, mortality rate as well as referral and discharge modalities were collected.

RESULTS

A total of 773 patients were included in the study after primary triage. There was a significant correlation between risk level and both hospitalisation rate (p < 0.001) and the length of hospitalisation (p = 0.001). Interestingly, this correlation was lower in patients over 70 years (r² = 0.101 vs. 0.045). Vital signs and mortality rate did not correlate significantly with the initial risk level. The average time for one triage process was 2.1 ± 3.9 min.

CONCLUSION

The German version of the MTS shows good correlation with central risk surrogates, but this correlation is weaker in the subgroup of elderly patients. As the original English version, it does not predict long-term mortality. In clinical practice, the German version of the MTS is as good as the original version in enabling the urgency of treatment to be rapidly assessed so that resource allocation can be optimised.

Differential effects of ifosfamide on dendritic cell-mediated stimulation of T cell interleukin-2 production, natural killer cell cytotoxicity and interferon-gamma production

Ifosfamide is a DNA-alkylating agent used frequently in chemotherapy of human malignancies. Ifosfamide and its major decomposition products deplete intracellular glutathione (GSH). Glutathione is the major intracellular thiol reductant that protects cells against oxidative injury. Ifosfamide depletion of intracellular GSH in human dendritic cells (DC), T cells and natural killer (NK) cells impairs their functional activity which can be restored by reconstituting GSH. Here we assessed the effect of ifosfamide on DC-mediated stimulation of NK cell proliferation via T cells and on direct DC stimulation of NK cell cytotoxicity and interferon (IFN)-gamma production. Indirect DC stimulation of NK cell proliferation via T cells and T cell-derived interleukin (IL)-2 were reduced by ifosfamide treatment of DC and reconstitution of GSH in DC restored both responses. When DC and NK cells were treated with ifosfamide, DC could overcome the negative effect of ifosfamide on NK cytotoxic function whereas NK cell IFN-gamma production was less efficiently restored. The ability of IL-2 activated NK cells to kill autologous immature DC or to induce DC maturation was reduced moderately by treatment of both cell types with ifosfamide. Overall, our results suggest that DC may stimulate anti-tumour effector cells in patients even if they had received treatment with chemotherapeutic agents such as ifosfamide.

Thrombin receptor-activating peptide sensitizes the human endothelial thrombin receptor

Receptor-operated effects of alpha-thrombin and of the thrombin receptor-activating peptide TRAP14 on cytoplasmic Ca2+ concentration ([Ca2+]i) were examined in fura 2-loaded endothelial cells. Experiments with hirudin showed that alpha-thrombin-induced Ca2+ influx requires the continuous presence of active alpha-thrombin. YFLLRNP, known to antagonize alpha-thrombin- and TRAP7-induced [Ca2+]i transients in platelets, did not antagonize [Ca2+]i transients in response to alpha-thrombin and TRAP14 in human umbilical vein endothelial cells (HUVEC). Repetitive short-term stimulations with alpha-thrombin desensitized [Ca2+]i transients to subsequent stimulations with either alpha-thrombin or TRAP14. In contrast, repeated short-term stimulations with TRAP14 sensitized [Ca2+]i transients to subsequent stimulations with either agonist. Blockade of Ca2+ influx by SKF-96365 abolished the sensitizing effect of TRAP14. The results indicate distinct characteristics of platelet and endothelial thrombin receptors and suggest that alpha-thrombin and TRAP14 activate the receptor differently. It appears that receptor desensitization occurs independently of TRAP14 binding and, hence, tethered ligand binding to and activation of the receptor. Persistent receptor desensitization after alpha-thrombin seems to depend on both alpha-thrombin binding to the hirudin-like receptor domain and the irreversible proteolytic cleavage of the receptor. It does not involve the TRAP14/tethered ligand binding site of the receptor. TRAP14 primes the receptor by a mechanism mediated by Ca2+ influx.