Autophagy: A Friend or Foe in Allergic Asthma?

Autophagy is a major self-degradative process through which cytoplasmic material, including damaged organelles and proteins, are delivered and degraded in the lysosome. Autophagy represents a dynamic recycling system that produces new building blocks and energy, essential for cellular renovation, physiology, and homeostasis. Principal autophagy triggers include starvation, pathogens, and stress. Autophagy plays also a pivotal role in immune response regulation, including immune cell differentiation, antigen presentation and the generation of T effector responses, the development of protective immunity against pathogens, and the coordination of immunometabolic signals. A plethora of studies propose that both impaired and overactive autophagic processes contribute to the pathogenesis of human disorders, including infections, cancer, atherosclerosis, autoimmune and neurodegenerative diseases. Autophagy has been also implicated in the development and progression of allergen-driven airway inflammation and remodeling. Here, we provide an overview of recent studies pertinent to the biology of autophagy and molecular pathways controlling its activation, we discuss autophagy-mediated beneficial and detrimental effects in animal models of allergic diseases and illuminate new advances on the role of autophagy in the pathogenesis of human asthma. We conclude contemplating the potential of targeting autophagy as a novel therapeutic approach for the management of allergic responses and linked asthmatic disease.

Platelet RNA Splicing Profiles Can Distinguish IgM MGUS Patients from Healthy Individuals

Introduction Within the general population over 50 years, 3% is affected with a monoclonal gammopathy of undetermined significance (MGUS). Although MGUS generally demands no treatment, interest in treating premalignant stages to prevent progression to overt malignancies has grown. Better insight in processes underlying progression of MGUS is therefore warranted. Platelet RNA profiles have been shown to reflect information on the topical tumor environment in various cancer types, including multiple myeloma (MM). Our aim was to investigate whether IgM MGUS patients can be distinguished from healthy controls (HCs) using platelet RNA splicing profiles, and to relate IgM MGUS splicing profiles to genes associated with Waldenström's Macroglobulinemia (WM). Methods Twenty-four IgM MGUS patients with presence of a paraprotein confirmed through immunofixation consented to participation. The thromboSeq protocol for platelet RNA sequencing (RNA-Seq) based classification (Best et al. Nat Protoc 2019) was used to acquire platelet RNA profiles from all MGUS subjects. RNA was extracted from platelets isolated from whole blood. After reverse transcription and SMARTer amplification, 100 bp single-read sequencing was performed on the Illumina Hiseq 2500 platform. Raw sequencing data were processed with Trimmomatic, aligned to a reference genome with STAR and mapped with HTSeq. Mapping data of 29 age and blood storage time matched HCs were also included in the analysis. Differential expression of spliced RNAs expressed as log2 fold change (logFC) was assessed with a likelihood-ratio ANOVA and visualized in a heatmap constructed with differentially spliced RNAs that passed the particle swarm optimized (PSO) false discovery rate (FDR) threshold. RNA profiles were further explored and related to WM and MM by DAVID gene ontology enrichment analyses. Results Mean age in the MGUS and HC groups was 67.2 (SD 7.7) and 66.9 (SD 6.7) years. Thirteen of 24 MGUS patients suffered from IgM mediated anti-myelin associated glycoprotein (MAG) neuropathy; the other 11 were asymptomatic. Of 3,426 high-abundant spliced RNAs detected, 1,371 demonstrated significant differential expression (FDR <0.05) and allowed perfect distinction of MGUS from HCs after PSO (Fig. 1; P <0.0001). The two distinct MGUS phenotypes (neuropathy vs. asymptomatic) could not be distinguished. Top 50 overexpressed RNA isoforms were mainly involved in apoptotic processes, transcription regulation, cellular defense response and immune response regulation. WM associated genes (logFC in parentheses) BCL7C (1.35), CASP8 (1.75), CD79A (2.65), CD81 (1.58), DUSP1 (2.32), HLA-DRB1 (1.83), JAK3 (0.65), NFKBIA (3.59), NFKB2 (1.63), REL (1.35) and TNFRSF14 (0.75), as well as MM associated JUND (4.61) and CCNL1 (3.11), were overexpressed in MGUS. TNFAIP3, negatively regulating the NF-κB pathway, was highly overexpressed (logFC 4.07). JAK1 and JAK2 mRNAs were mildly though significantly depleted in the MGUS group. We also found overexpression of CCNL2 (1.81), MS4A1 (2.17) and WNK1 (0.79), which have been shown to be enriched in WM relative to IgM MGUS. Top 50 depleted RNAs were mainly involved in protein phosphorylation, intracellular signal transduction and response to tumor necrosis factor. CASP3 (-1.43), CASP4 (-0.62) and TNFSF4 (-0.99) mRNAs, of which overexpression is associated with WM, were depleted in MGUS. Conclusions For the first time, we have demonstrated widespread differential expression of spliced RNAs in platelets of MGUS patients as compared to healthy controls. We found evidence of overexpression of various genes that have been associated with WM. The differences were mainly in pathways related to apoptosis, signaling and immune response regulation. This is in line with findings that balanced elevation of free light chains, possibly due to a chronic inflammatory state, increases risk of developing a monoclonal gammopathy (Kumar et al. Blood Cancer J 2019). Overexpression of NFKBIA, NFKB2 andTNFAIP3 in MGUS possiblysuggests activation of the NF-κB pathway, a key step in MYD88 mediated progression to WM. JAK subtype expression levels may reflect that the JAK/STAT pathway, also important for progression to WM, has not (yet) been aberrantly activated in our MGUS subjects. Future research could be focused on studying the development of MGUS and MGUS progression to WM and MM using differentially expressed splice junctions in platelets. Disclosures Minnema: Amgen: Honoraria; Celgene Corporation: Honoraria, Research Funding; Gilead: Honoraria; Jansen Cilag: Honoraria; Servier: Honoraria.

The Immunomodulatory Potential of Wharton’s Jelly Mesenchymal Stem/Stromal Cells

The benefits attributed to mesenchymal stem/stromal cells (MSC) in cell therapy applications are mainly attributed to the secretion of factors, which exhibit immunomodulatory and anti-inflammatory effects and stimulate angiogenesis. Despite the desirable features such as high proliferation levels, multipotency, and immune response regulation, there are important variables that must be considered. Although presenting similar morphological aspects, MSC collected from different tissues can form heterogeneous cellular populations and, therefore, manifest functional differences. Thus, the source of MSC should be a factor to be considered in the development of novel therapies. The following text presents an updated review of recent research outcomes related to Wharton’s jelly mesenchymal stem/stromal cells (WJ-MSC), harvested from umbilical cords and considered novel and potential candidates for the development of cell-based approaches. This text highlights information on how WJ-MSC affect immune responses in comparison with other sources of MSC.

Kallikrein 12 Regulates Innate Resistance of Murine Macrophages against Mycobacterium bovis Infection by Modulating Autophagy and Apoptosis

Mycobacterium bovis (M. bovis) is a member of the Mycobacterium tuberculosis (Mtb) complex causing bovine tuberculosis (TB) and imposing a high zoonotic threat to human health. Kallikreins (KLKs) belong to a subgroup of secreted serine proteases. As their role is established in various physiological and pathological processes, it is likely that KLKs expression may mediate a host immune response against the M. bovis infection. In the current study, we report in vivo and in vitro upregulation of KLK12 in the M. bovis infection. To define the role of KLK12 in immune response regulation of murine macrophages, we produced KLK12 knockdown bone marrow derived macrophages (BMDMs) by using siRNA transfection. Interestingly, the knockdown of KLK12 resulted in a significant downregulation of autophagy and apoptosis in M. bovis infected BMDMs. Furthermore, we demonstrated that this KLK12 mediated regulation of autophagy and apoptosis involves mTOR/AMPK/TSC2 and BAX/Bcl-2/Cytochrome c/Caspase 3 pathways, respectively. Similarly, inflammatory cytokines IL-1β, IL-6, IL-12 and TNF-α were significantly downregulated in KLK12 knockdown macrophages but the difference in IL-10 and IFN-β expression was non-significant. Taken together, these findings suggest that upregulation of KLK12 in M. bovis infected murine macrophages plays a substantial role in the protective immune response regulation by modulating autophagy, apoptosis and pro-inflammatory pathways. To our knowledge, this is the first report on expression and the role of KLK12 in the M. bovis infection and the data may contribute to a new paradigm for diagnosis and treatment of bovine TB.