Cost Analysis of Target Lesion Revascularisation in Patients With Femoropopliteal In Stent Re-Stenosis or Occlusion: The COSTLY-TLR Study.

OBJECTIVE: To report the cost of target lesion revascularisation procedures (TLR) for femoropopliteal peripheral artery disease (PAD) following stenting, from a healthcare payer's perspective. METHODS: European multicentre study involving consecutive patients requiring femoropopliteal TLR (January 2017 - December 2021). The primary outcome was overall cost (euros) associated with a TLR procedure from presentation to discharge. Exact costs per constituent, clinical characteristics, and early outcomes were reported. RESULTS: This study included 482 TLR procedures (retrospectively, 13 hospitals, six countries): 56% were female, mean age was 75 ± 2 years, 61% were Rutherford class 5 or 6, 67% had Tosaka class 3 disease, and 16% had common femoral or iliac involvement. A total of 52% were hybrid procedures and 6% involved open surgery only. Technical success was 70%, 30 day mortality rate was 1%, and the 30 day major amputation rate was 4%. Most costs were for operating time during the TLR (healthcare professionals' salaries, indirect and estate costs), with a mean of: €21 917 ± €2 110 for all procedures; €23 337 ± €8 920 for open procedures; €12 903 ± €3 108 for endovascular procedures; and €22 806 ± €3 977 for hybrid procedures. In a regression analysis, procedure duration was the main parameter associated with higher overall TLR costs (coefficient, 2.77; standard error, 0.88; p < .001). The mean cost per operating minute of TLR (indirect, estate costs, all salaried staff present included) was €177 and the mean cost per night stay in hospital (outside intensive care unit) was €356. The mean cost per overnight intensive care unit stay (minimum of 8 hours per night) was €1 193. CONCLUSION: The main driver of the considerable peri-procedure costs associated with femoropopliteal TLR was procedure time.

Inflammasome Activation in Human Macrophages: IL-1ß Cleavage Detection by Fully Automated Capillary-Based Immunoassay.

Interleukin (IL)-1ß is a key mediator of inflammation and activates via pattern recognition receptors (PRR) of the inflammasome family by proteolytic maturation. Proteolysis is driven by proteases such as caspase-1 (also known as IL-1 converting enzyme, ICE) and converts the intact pro-IL-1ß ~31 kDa pro-peptide into a mature, ~17 kDa form that can exit cells through nanomolecular pores or via microvesicles. Whereas pro-IL-1ß fails to trigger IL-1 receptor (IL-1R) activation, mature IL-1ß, upon release from the cell, triggers pleiotropic downstream effects, establishing an inflammatory state. Hence, being able to detect IL-1ß conversion is physiologically relevant for measuring inflammation, but it cannot be easily accomplished by conventional ELISA or flow cytometry as most commercially available antibodies do not discriminate mature and pro-form. Furthermore, unlike for other cytokines, the mere induction and translation of IL1B mRNA cannot serve as a proxy of inflammasome PRR activation. Rather the cleavage of IL-1ß needs to be verified. Hence, conventional immunoblotting has emerged as the gold standard for demonstrating inflammasome activation as the difference in molecular weight between pro- and mature form can easily be detected. However, conventional immunoblotting suffers from poor standardization, quantification, and reproducibility, may require sample concentration, and is also not suitable for medium to high throughput. Some of these shortcomings are prohibitive for analysis of human primary samples but can be overcome by fully automated capillary-based immunoassay as we outline here. We here provide a practical guide to quantify pro- vs mature IL-1ß directly from unconcentrated supernatants of human monocyte-derived macrophages. The assay may be useful for more standardized and medium-throughput analysis in these cells or other biospecimen.

Chitin oligomers promote lymphoid innate and adaptive immune cell activation.

Chitin is a highly abundant N-acetylglucosamine polysaccharide that has been linked to immune responses in the context of fungal infections and allergic asthma, especially to T helper 2 immune responses. Unfortunately, due to the frequent use of crude chitin preparations of unknown purity and degree of polymerization, there is still great uncertainty about how chitin activates different parts of the human immune system. We recently identified chitin oligomers of 6 N-acetylglucosamine units as the smallest immunologically active chitin motif and the innate immune receptor TLR2 as a primary chitin sensor on human and murine myeloid cells, but the response of further immune cells (e.g. lymphoid cells) to oligomeric chitin has not been investigated. Our analysis of primary human immune cells now shows that chitin oligomers activate immune responses of both innate and adaptive lymphocytes: notably, chitin oligomers activated natural killer cells but not B lymphocytes. Moreover, chitin oligomers induced maturation of dendritic cells and enabled potent CD8+ T-cell recall responses. Our results suggest that chitin oligomers not only trigger immediate innate responses in a limited range of myeloid cells but also exert critical activities across the entire human immune system. This highlights chitin oligomer immune activation as an interesting and broadly applicable potential target for both adjuvant development and therapeutic interference in chitin-mediated pathologies.

Use of Secondary Iliac Branch Devices after Previous Endovascular Abdominal and Thoraco-Abdominal Aortic Aneurysm Repair.

OBJECTIVE: To assess the safety and effectiveness of iliac branch devices (IBDs), as secondary procedure, for the treatment of type Ib endoleak or evolution of iliac artery disease after prior endovascular aortic repair (EVAR) for thoraco-abdominal (TAAAs) or abdominal aortic aneurysms (AAAs). METHODS: A multicentre observational study of three European centres. The study included 75 patients (age 71 ± 9 years, 96% men) with previous EVAR (n = 64, 85%) or fenestrated or branched (FB) EVAR (n = 11, 15%). Overall, 88 IBDs were implanted to treat aneurysmal iliac artery evolution in 40 (53%) and type Ib endoleak in 35 (47%) cases, respectively. Thirteen (17%) patients received bilateral IBDs. Internal iliac artery (IIA) catheterisation was done through a transaxillary access (n = 82, 93%) or up and over (n = 6, 7%) technique. The primary endpoint was technical success. Secondary endpoints were 30 day major adverse event, early and long term freedom from re-intervention and target vessel instability. RESULTS: All procedures were technically successful (100%). During hospitalisation, there were four (5%) major adverse events and three (4%) early re-interventions, but no death, stroke, or damage to previous endografts. The median follow up was 47 (interquartile range 42) months, and the five year survival rate was 78 ± 6% with no aortic related death. Cox's regression analysis showed pre-operative renal function impairment (hazard ratio [HR] 3.4; 95% confidence interval [CI] 1.1 - 10.1; p = .033), and primary TAAA repair (HR 6.1; 95% CI 1.6-22.3; p = .006) as independent factors for long term mortality. Freedom from re-interventions was 85 ± 4% at five years with 11 (12%) cases (five endoleaks, four IBD thromboses, two stenoses). IIA instability was reported in three (3%) limbs and freedom from IIA instability was 95 ± 3% after 60 months. CONCLUSION: Secondary IBD after EVAR is a safe and effective procedure with high technical success and low complication rates. The technique of choice to revascularise the IIA seems not to affect early and follow up results. Long term durability of IBD repair is acceptable with low rates of IIA re-intervention.

BTK operates a phospho-tyrosine switch to regulate NLRP3 inflammasome activity.

Activity of the NLRP3 inflammasome, a critical mediator of inflammation, is controlled by accessory proteins, posttranslational modifications, cellular localization, and oligomerization. How these factors relate is unclear. We show that a well-established drug target, Bruton's tyrosine kinase (BTK), affects several levels of NLRP3 regulation. BTK directly interacts with NLRP3 in immune cells and phosphorylates four conserved tyrosine residues upon inflammasome activation, in vitro and in vivo. Furthermore, BTK promotes NLRP3 relocalization, oligomerization, ASC polymerization, and full inflammasome assembly, probably by charge neutralization, upon modification of a polybasic linker known to direct NLRP3 Golgi association and inflammasome nucleation. As NLRP3 tyrosine modification by BTK also positively regulates IL-1ß release, we propose BTK as a multifunctional positive regulator of NLRP3 regulation and BTK phosphorylation of NLRP3 as a novel and therapeutically tractable step in the control of inflammation.

Absence of Non-Canonical, Inhibitory MYD88 Splice Variants in B Cell Lymphomas Correlates With Sustained NF-κB Signaling.

Gain-of-function mutations of the TLR adaptor and oncoprotein MyD88 drive B cell lymphomagenesis via sustained NF-κB activation. In myeloid cells, both short and sustained TLR activation and NF-κB activation lead to the induction of inhibitory MYD88 splice variants that restrain prolonged NF-κB activation. We therefore sought to investigate whether such a negative feedback loop exists in B cells. Analyzing MYD88 splice variants in normal B cells and different primary B cell malignancies, we observed that MYD88 splice variants in transformed B cells are dominated by the canonical, strongly NF-κB-activating isoform of MYD88 and contain at least three novel, so far uncharacterized signaling-competent splice isoforms. Sustained TLR stimulation in B cells unexpectedly reinforces splicing of NF-κB-promoting, canonical isoforms rather than the 'MyD88s', a negative regulatory isoform reported to be typically induced by TLRs in myeloid cells. This suggests that an essential negative feedback loop restricting TLR signaling in myeloid cells at the level of alternative splicing, is missing in B cells when they undergo proliferation, rendering B cells vulnerable to sustained NF-κB activation and eventual lymphomagenesis. Our results uncover MYD88 alternative splicing as an unappreciated promoter of B cell lymphomagenesis and provide a rationale why oncogenic MYD88 mutations are exclusively found in B cells.

The fungal ligand chitin directly binds TLR2 and triggers inflammation dependent on oligomer size.

Chitin is the second most abundant polysaccharide in nature and linked to fungal infection and asthma. However, bona fide immune receptors directly binding chitin and signaling immune activation and inflammation have not been clearly identified because polymeric crude chitin with unknown purity and molecular composition has been used. By using defined chitin (N-acetyl-glucosamine) oligomers, we here identify six-subunit-long chitin chains as the smallest immunologically active motif and the innate immune receptor Toll-like receptor (TLR2) as a primary fungal chitin sensor on human and murine immune cells. Chitin oligomers directly bind TLR2 with nanomolar affinity, and this fungal TLR2 ligand shows overlapping and distinct signaling outcomes compared to known mycobacterial TLR2 ligands. Unexpectedly, chitin oligomers composed of five or less subunits are inactive, hinting to a size-dependent system of immuno-modulation that appears conserved in plants and humans. Since blocking of the chitin-TLR2 interaction effectively prevents chitin-mediated inflammation in vitro and in vivo, our study highlights the chitin-TLR2 interaction as a potential target for developing novel therapies in chitin-related pathologies and fungal disease.

Oncogenic MYD88 mutations in lymphoma: novel insights and therapeutic possibilities.

Oncogenic MYD88 mutations, most notably the Leu 265 Pro (L265P) mutation, were recently identified as potential driver mutations in various B-cell non-Hodgkin Lymphomas (NHLs). The L265P mutation is now thought to be common to virtually all NHLs and occurs in between 4 and 90% of cases, depending on the entity. Since it is tumor-specific, the mutation, and the pathways it regulates, might serve as advantageous therapeutic targets for both conventional chemotherapeutic intervention, as well as immunotherapeutic strategies. Here, we review recent progress on elucidating the molecular and cellular processes affected by the L265P mutation of MYD88, describe a new in vivo model for MyD88 L265P-mediated oncogenesis, and summarize how these findings could be exploited therapeutically by specific targeting of signaling pathways. In addition, we summarize current and explore future possibilities for conceivable immunotherapeutic approaches, such as L265P-derived peptide vaccination, adoptive transfer of L265P-restricted T cells, and use of T-cell receptor-engineered T cells. With clinical trials regarding their efficacy rapidly expanding to NHLs, we also discuss potential combinations of immune checkpoint inhibitors with the described targeted chemotherapies of L265P signaling networks, and/or with the above immunological approaches as potential ways of targeting MYD88-mutated lymphomas in the future.

Interleukin-1 receptor-associated kinase 4 (IRAK4) plays a dual role in myddosome formation and Toll-like receptor signaling.

Toll-like receptors (TLRs) form part of the host innate immune system, in which they act as sensors of microbial and endogenous danger signals. Upon TLR activation, the intracellular Toll/interleukin-1 receptor domains of TLR dimers initiate oligomerization of a multiprotein signaling platform comprising myeloid differentiation primary response 88 (MyD88) and members of the interleukin-1 receptor-associated kinase (IRAK) family. Formation of this myddosome complex initiates signal transduction pathways, leading to the activation of transcription factors and the production of inflammatory cytokines. To date, little is known about the assembly and disassembly of the myddosome and about the mechanisms by which these complexes mediate multiple downstream signaling pathways. Here, we isolated myddosome complexes from whole-cell lysates of TLR-activated primary mouse macrophages and from IRAK reporter macrophages to examine the kinetics of myddosome assembly and disassembly. Using a selective inhibitor of IRAK4's kinase activity, we found that whereas TLR cytokine responses were ablated, myddosome formation was stabilized in the absence of IRAK4's kinase activity. Of note, IRAK4 inhibition had only a minimal effect on NF-κB and mitogen-activated protein kinase (MAPK) signaling. In summary, our results indicate that IRAK4 has a critical scaffold function in myddosome formation and that its kinase activity is dispensable for myddosome assembly and activation of the NF-κB and MAPK pathways but is essential for MyD88-dependent production of inflammatory cytokines. Our findings suggest that the scaffold function of IRAK4 may be an attractive target for treating inflammatory and autoimmune diseases.

The NLR family pyrin domain-containing 11 protein contributes to the regulation of inflammatory signaling.

Mammalian Nod-like receptor (NLR) proteins contribute to the regulation and induction of innate and adaptive immunity in mammals, although the function of about half of the currently identified NLR proteins remains poorly characterized. Here we analyzed the function of the primate-specific NLRP11 gene product. We show that NLRP11 is highly expressed in immune cells, including myeloid cells, B cells, and some B cell lymphoma lines. Overexpression of NLRP11 in human cells did not trigger key innate immune signaling pathways, including NF-κB and type I interferon responses. NLRP11 harbors a pyrin domain, which is responsible for inflammasome formation in related NLR proteins. However, NLRP11 did not interact with the inflammasome adaptor protein ASC, and it did not trigger caspase-1 activation. By contrast, expression of NLRP11 specifically repressed NF-κB and type I interferon responses, two key innate immune pathways involved in inflammation. This effect was independent of the pyrin domain and ATPase activity of NLRP11. siRNA-mediated knockdown of NLRP11 in human myeloid THP1 cells validated these findings and revealed enhanced lipopolysaccharide and Sendai virus-induced cytokine and interferon responses, respectively, in cells with reduced NLRP11 expression. In summary, our work identifies a novel role of NLRP11 in the regulation of inflammatory responses in human cells.

Generation of Innate Immune Reporter Cells Using Retroviral Transduction.

Innate immune cells are notoriously difficult to transfect; however, retroviruses can be used to stably integrate genes of interest into the host genome of primary or immortalized immune cells resulting in the generation of reporter cells. Here, we provide a detailed protocol covering the production of retroviruses, retroviral infection of innate immune target cells (including isolation and differentiation of murine bone marrow cells to macrophages), and several methods for enrichment of positively transduced cells.

HLA class I-restricted MYD88 L265P-derived peptides as specific targets for lymphoma immunotherapy.

Genome sequencing has uncovered an array of recurring somatic mutations in different non-Hodgkin lymphoma (NHL) subtypes. If affecting protein-coding regions, such mutations may yield mutation-derived peptides that may be presented by HLA class I proteins and recognized by cytotoxic T cells. A recurring somatic and oncogenic driver mutation of the Toll-like receptor adaptor protein MYD88, Leu265Pro (L265P) was identified in up to 90% of different NHL subtype patients. We therefore screened the potential of MYD88L265P-derived peptides to elicit cytotoxic T cell responses as tumor-specific neoantigens. Based on in silico predictions, we identified potential MYD88L265P-containing HLA ligands for several HLA class I restrictions. A set of HLA class I MYD88L265P-derived ligands elicited specific cytotoxic T cell responses for HLA-B*07 and -B*15. These data highlight the potential of MYD88L265P mutation-specific peptide-based immunotherapy as a novel personalized treatment approach for patients with MYD88L265P+ NHLs that may complement pharmacological approaches targeting oncogenic MyD88 L265P signaling.