Soluble calreticulin induces tumor necrosis factor-α (TNF-α) and interleukin (IL)-6 production by macrophages through mitogen-activated protein kinase (MAPK) and NFκB signaling pathways

A Review on Neuroinflammatory Pathway Mediating Through Ang-II/AT1 Receptors and a Novel Approach for the Treatment of Cerebral Ischemia in Combination with ARB's and Ceftriaxone

Background

Ischemic stroke is one of the prevalent neurodegenerative disorders; it is generally characterized by sudden abruption of blood flow due to thromboembolism and vascular abnormalities, eventually impairing the supply of oxygen and nutrients to the brain for its metabolic needs. Oxygen-glucose deprived conditions provoke the release of excessive glutamate, which causes excitotoxicity.

Summary

Recent studies suggest that circulatory angiotensin-II (Ang-II) has an imperative role in initiating detrimental events through binding central angiotensin 1 (AT1) receptors. Insufficient energy metabolites and essential ions often lead to oxidative stress during ischemic reperfusion, which leads to the release of proinflammatory mediators such as interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and cytokines like interleukin-18 (IL-18) and interleukin- 1beta (IL-1β). The transmembrane glutamate transporters, excitatory amino acid transporter-2 (EAAT-2), which express in astroglial cells, have a crucial role in the clearance of glutamate from its releasing site and convert glutamate into glutamine in normal circumstances of brain physiology.

Key Message

During cerebral ischemia, an impairment or dysfunction of EAAT-2 attributes the risk of delayed neuronal cell death. Earlier studies evidencing that angiotensin receptor blockers (ARB) attenuate neuroinflammation by inhibiting the Ang-II/AT1 receptor-mediated inflammatory pathway and that ceftriaxone ameliorates the excitotoxicity-induced neuronal deterioration by enhancing the transcription and expression of EAAT-2 via the nuclear transcriptional factor kappa-B (NF-kB) signaling pathway. The present review will briefly discuss the mechanisms involved in Ang-II/AT1-mediated neuroinflammation, ceftriaxone-induced EAAT-2 expression, and the repurposing hypothesis of the novel combination of ARBs and ceftriaxone for the treatment of cerebral ischemia.

Two novel teleost calreticulins PoCrt-1/2, with bacterial binding and agglutination activity, are involved in antibacterial immunity

Calreticulin (Crt), a conserved lectin-like pleiotropic protein, plays crucial roles in mammalian immune response. In fish, the immunological function of Crt is limited investigated. Herein, we studied the antibacterial immunity of two type of Crt homologues (i.e. PoCrt-1 and PoCrt-2) in Japanese flounder (Paralichthys olivaceus). PoCrt-1 and PoCrt-2 are composed of 419 and 427 amino acid residues respectively, with 69.09% overall sequence identities with each other. Both PoCrt-1 and PoCrt-2 contain a signal peptide and three functional domains i.e. N-, P- and C-domains. Both PoCrt-1 and PoCrt-2 were constitutively expressed at various tissues with highest expression level in liver, and obviously regulated by Edwardsiella tarda and Vibrio harveyi. Furthermore, recombinant PoCrt-1 and PoCrt-2 (rPoCrt-1 and rPoCrt-2) could bind to different Gram-negative bacteria with highest binding index with E. tarda. At same time, in vitro rPoCrt-1 and rPoCrt-2 could agglutinate E. tarda, V. harveyi, and Vibrio anguillarum, and inhibit the bacterial growth. Similarly, in vivo rPoCrt-1 and rPoCrt-2 could significantly suppress the dissemination of E. tarda. Overall, these observations add new insights into the antibacterial immunity of Crt in P. olivaceus.

Mesenchymal Stromal Cells Facilitate Neutrophil-Trained Immunity by Reprogramming Hematopoietic Stem Cells

Novel therapeutics are urgently needed to prevent opportunistic infections in immunocompromised individuals undergoing cancer treatments or other immune-suppressive therapies. Trained immunity is a promising strategy to reduce this burden of disease. We previously demonstrated that mesenchymal stromal cells (MSCs) preconditioned with a class A CpG oligodeoxynucleotide (CpG-ODN), a Toll-like receptor 9 (TLR9) agonist, can augment emergency granulopoiesis in a murine model of neutropenic sepsis. Here, we used a chimeric mouse model to demonstrate that MSCs secrete paracrine factors that act on lineage-negative c-kit+ hematopoietic stem cells (HSCs), leaving them "poised" to enhance emergency granulopoiesis months after transplantation. Chimeric mice developed from HSCs exposed to conditioned media from MSCs and CpG-ODN-preconditioned MSCs showed significantly higher bacterial clearance and increased neutrophil granulopoiesis following lung infection than control mice. By Cleavage Under Targets and Release Using Nuclease (CUT&RUN) chromatin sequencing, we identified that MSC-conditioned media leaves H3K4me3 histone marks in HSCs at genes involved in myelopoiesis and in signaling persistence by the mTOR pathway. Both soluble factors and extracellular vesicles from MSCs mediated these effects on HSCs and proteomic analysis by mass spectrometry revealed soluble calreticulin as a potential mediator. In summary, this study demonstrates that trained immunity can be mediated by paracrine factors from MSCs to induce neutrophil-trained immunity by reprogramming HSCs for long-lasting functional changes in neutrophil-mediated antimicrobial immunity.

Calreticulin Expression in Human Carcinomas: A Systematic Review and Meta-Analysis

OBJECTIVE

The present study performed a systematic review and meta-analysis of observational studies on whether calreticulin levels could represent a prognostic factor in carcinoma patients. Calreticulin (CRT) is a multifunctional protein in the endoplasmic reticulum that can play distinct roles in different cancers.

METHODS

The search was performed in PubMed, Scopus, the Cochrane Library, Web of Science, Lilacs, Science Direct, Embase, Bireme, and SciELO databases. After a full-text evaluation, only 14 articles remained. The RoBANS tool assessed the risk of bias. The meta-analysis was performed with R software, and the odds ratio (OR) was the effect measure. The random effects model was chosen, and the quality of evidence was evaluated according to GRADE.

RESULT

The most frequent carcinomas were in the breasts and the colon. CRT expression varied according to carcinoma origin and type, but these diseases had a prevalence of high CRT levels, indicating tumor progression. The high CRT levels were associated with lymph node metastasis (OR = 3.06 [1.71; 5.48]/p = 0.0002/I2 = 0%). All included articles had a blinding bias.

CONCLUSION

High CRT levels may represent a prognostic factor for metastatic lymph nodes in carcinoma patients.

Chemotherapeutic drug-induced immunogenic cell death for nanomedicine-based cancer chemo-immunotherapy

Chemotherapy has been a conventional paradigm for cancer treatment, and multifarious chemotherapeutic drugs have been widely employed for decades with significant performances in suppressing tumors. Moreover, some of the antitumor chemotherapeutic agents, such as doxorubicin (DOX), oxaliplatin (OXA), cyclophosphamide (CPA) and paclitaxel (PTX), can also tackle tumors through the induction of immunogenic cell death (ICD) in tumor cells to trigger specific antitumor immune responses of the body and improve chemotherapy efficacy. In recent years, chemo-immunotherapy has attracted increasing attention as one of the most promising combination therapies to struggle with malignant tumors. Many effective antitumor therapies have benefited from the successful induction of ICD in tumors, which could incur the release of endogenous danger signals and tumor-associated antigens (TAAs), further stimulating antigen-presenting cells (APCs) and ultimately initiating efficient antitumor immunity. In this review, several well-characterized damage-associated molecular patterns (DAMPs) were introduced and the progress of ICD induced by representative chemotherapeutic drugs for nanomedicine-based chemo-immunotherapy was highlighted. In addition, the combination strategies involving ICD cooperated with other therapies were discussed. Finally, we shared some perspectives in chemotherapeutic drug-induced ICD for future chemo-immunotherapy. It was hoped that this review would provide worthwhile presentations and enlightenments for cancer chemo-immunotherapy.

Moonlighting Proteins Are Important Players in Cancer Immunology

Plasticity and adaptation to environmental stress are the main features that tumor and immune system share. Except for intrinsic and high-defined properties, cancer and immune cells need to overcome the opponent's defenses by activating more effective signaling networks, based on common elements such as transcriptional factors, protein-based complexes and receptors. Interestingly, growing evidence point to an increasing number of proteins capable of performing diverse and unpredictable functions. These multifunctional proteins are defined as moonlighting proteins. During cancer progression, several moonlighting proteins are involved in promoting an immunosuppressive microenvironment by reprogramming immune cells to support tumor growth and metastatic spread. Conversely, other moonlighting proteins support tumor antigen presentation and lymphocytes activation, leading to several anti-cancer immunological responses. In this light, moonlighting proteins could be used as promising new potential targets for improving current cancer therapies. In this review, we describe in details 12 unprecedented moonlighting proteins that during cancer progression play a decisive role in guiding cancer-associated immunomodulation by shaping innate or adaptive immune response.

Identification, molecular characterization, expression analysis and wound-healing ability of multifunctional calreticulin from big-belly seahorse Hippocampus abdominalis

Calreticulin (CRT) is a multifunctional ubiquitous protein that is widely presented in all cells in eukaryotes except erythrocytes. CRT is well known for diverse cellular functions such as endoplasmic reticulum (ER)-specialized protein quality control during protein synthesis and folding, in-vivo Ca²⁺ homeostasis, antigen presentation, phagocytosis, wound-healing, proliferation, adhesion, and migration of cells. In the current study, we identified CRT from Hippocampus abdominalis (HaCRT) and analyzed expression profiles and functional properties. The cDNA sequence of HaCRT was identified with an open reading frame of 1226 bp. The molecular weight of HaCRT was estimated as 49 kDa. The in-silico study revealed conserved sequence arrangements such as two CRT signature motifs (5'-KHEQSIDCGGGYVKVF-3' and 5'-LMFGPDICG-3'), triplicate repeats (5'-IKDPEAKKPEDWD-3', 5'-IPDPDDTKPEDWD-3', 5'-IPDPDAKKPDDWD-3'), signal peptide and an ER-targeting 5'-KDEL-3' sequence of HaCRT. Close sequence similarity of HaCRT was observed with Hippocampus comes from phylogenetic analysis and pairwise sequence comparison. From quantitative polymerase chain reaction (qPCR) results, HaCRT was ubiquitously distributed in all tested tissues and expression levels of HaCRT were significantly modulated in blood, liver and gill tissues after stimulation with Streptococcus iniae, Edwardsiella tarda, polyinosinic:polycytidylic acid, and lipopolysaccharides. Bacterial- and pathogen-associated molecular patterns-binding activities were observed with recombinant HaCRT (rHaCRT). The treatment of murine macrophages with rHaCRT induced the expression of immune genes, such as tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), inducible nitric oxide synthase (iNOS), and interleukin-1β (IL-1β). Furthermore, rHaCRT exhibited wound-healing ability. Based on the results from the above study, we suggest that HaCRT play an indispensable role in the immunity of big-belly seahorses by recognition and elimination of pathogens as well as the tissue repairing process.

IL-38: A novel cytokine in systemic lupus erythematosus pathogenesis

IL‐38 is a newly identified cytokine that belongs to the IL‐1 family. In our previous study, we found elevated plasma levels of IL‐38 in patients with systemic lupus erythematosus (SLE). However, the clear relationship of IL‐38 expression in plasma, peripheral blood mononuclear cells (PBMCs) and clinical and laboratory features needs elucidation. Additionally, we evaluated the possible role of IL‐38 in regulating production of inflammatory cytokines in PBMCs in vitro. A pristane‐induced murine lupus model was used to further demonstrate the effects of IL‐38 on cytokines in vivo and discuss the significance of IL‐38 in lupus development. The results showed that mRNA expression of IL‐38 in PBMCs of patients with SLE was elevated compared with volunteers, and expression of IL‐38 in both plasma and PBMCs was strongly related to clinical features, such as haematuria and proteinuria, and correlated with a SLEDAI score. Plasma levels of TNF‐α, IL‐1β, IL‐6 and IL‐23 were elevated in patients with SLE and were related to plasma levels of IL‐38. In vitro, PBMCs of patients with SLE stimulated with IL‐38 showed a decreased expression of the four inflammatory cytokines compared with PBMCs of patients without treatment. Interestingly, IL‐38 administration in lupus mice significantly reduced the development of lupus, such as reduced proteinuria, improved histological examinations of the kidneys and down‐regulated inflammatory cytokines. In conclusion, IL‐38 may suppress synthesis of pro‐inflammatory cytokines and therefore regulate lupus pathogenesis.

Calreticulin exploits TGF-β for extracellular matrix induction engineering a tissue regenerative process

Topical application of extracellular calreticulin (eCRT), an ER chaperone protein, in animal models enhances wound healing and induces tissue regeneration evidenced by epidermal appendage neogenesis and lack of scarring. In addition to chemoattraction of cells critical to the wound healing process, eCRT induces abundant neo-dermal extracellular matrix (ECM) formation by 3 days post-wounding. The purpose of this study was to determine the mechanisms involved in eCRT induction of ECM. In vitro, eCRT strongly induces collagen I, fibronectin, elastin, α-smooth muscle actin in human adult dermal (HDFs) and neonatal fibroblasts (HFFs) mainly via TGF-β canonical signaling and Smad2/3 activation; RAP, an inhibitor of LRP1 blocked eCRT ECM induction. Conversely, eCRT induction of α5 and β1 integrins was not mediated by TGF-β signaling nor inhibited by RAP. Whereas eCRT strongly induces ECM and integrin α5 proteins in K41 wild-type mouse embryo fibroblasts (MEFs), CRT null MEFs were unresponsive. The data show that eCRT induces the synthesis and release of TGF-β3 first via LRP1 or other receptor signaling and later induces ECM proteins via LRP1 signaling subsequently initiating TGF-β receptor signaling for intracellular CRT (iCRT)-dependent induction of TGF-β1 and ECM proteins. In addition, TGF-β1 induces 2-3-fold higher level of ECM proteins than eCRT. Whereas eCRT and iCRT converge for ECM induction, we propose that eCRT attenuates TGF-β-mediated fibrosis/scarring to achieve tissue regeneration.

Proteins involved in the endoplasmic reticulum stress are modulated in synovitis of osteoarthritis, chronic pyrophosphate arthropathy and rheumatoid arthritis, and correlate with the histological inflammatory score

It is now well recognized that osteoarthritis (OA) synovial membrane presents inflammatory components. The aim of this work is to provide evidence that similar inflammatory mechanisms exist in synovial membrane (n = 24) obtained from three pathologies presenting altogether an inflammatory gradient: OA, chronic pyrophosphate arthropathy (CPPA) and rheumatoid arthritis (RA). Synovial biopsies were first characterized by a histological score based on synovial hyperplasia and infiltration of lymphocytes, plasma cells, polymorphonuclear and macrophages. All biopsies were also analyzed by 2D-nano-UPLC-ESI-Q-Orbitrap for protein identification and quantification. Protein levels were correlated with the histological score. Histological score was in the range of 3 to 8 for OA, 5 to 13 for CPPA and 12 to 17 for RA. Of the 4,336 proteins identified by mass spectrometry, 51 proteins were selected for their strong correlation (p < 0.001) with the histological score of which 11 proteins (DNAJB11, CALR, ERP29, GANAB, HSP90B1, HSPA1A, HSPA5, HYOU1, LMAN1, PDIA4, and TXNDC5) were involved in the endoplasmic reticulum (ER) stress. Protein levels of S100A8 and S100A9 were significantly higher in RA compared to OA (for both) or to CPPA (for S100A8 only) and also significantly correlated with the histological score. Eighteen complement component proteins were identified, but only C1QB and C1QBP were weakly correlated with the histological score. This study highlights the inflammatory gradient existing between OA, CPPA and RA synovitis either at the protein level or at the histological level. Inflamed synovitis was characterized by the overexpression of ER stress proteins.

Anti-Glucosylsphingosine Autoimmunity, JAK2V617F-Dependent Interleukin-1β and JAK2V617F-Independent Cytokines in Myeloproliferative Neoplasms

Simple Summary

Inflammation plays a major role in myeloproliferative neoplasms (MPNs) as regulator of malignant cell growth and mediator of clinical symptoms. Yet chronic inflammation may also be an early event that facilitates the development of MPNs. Here we analysed 42 inflammatory cytokines and report that in patients as well as in UT-7 cell lines, interleukin-1β and interferon-induced protein 10 (IP-10) were the main inflammatory molecules found to be induced by JAK2V617F, the most frequent driving mutation in MPNs. All other inflammatory cytokines were not linked to JAK2V617F, which implies that inflammation likely precedes MPN development at least in subsets of MPN patients. Consistently, a possible cause of early, chronic inflammation may be auto-immunity against glucolipids: we report that 20% of MPN patients presented with anti-glucosylsphingoside auto-antibodies. Since existing treatments can reduce glucosylsphingoside, this lysosphingolipid could become a new therapeutic target for subsets of MPN patients, in addition to JAK2V617F and inflammation.

Abstract

Inflammatory cytokines play a major role in myeloproliferative neoplasms (MPNs) as regulators of the MPN clone and as mediators of clinical symptoms and complications. Firstly, we investigated the effect of JAK2V617F on 42 molecules linked to inflammation. For JAK2V617F-mutated patients, the JAK2V617F allele burden (%JAK2V617F) correlated with the levels of IL-1β, IL-1Rα, IP-10 and leptin in polycythemia vera (PV), and with IL-33 in ET; for all other molecules, no correlation was found. Cytokine production was also studied in the human megakaryocytic cell line UT-7. Wild-type UT-7 cells secreted 27/42 cytokines measured. UT-7 clones expressing 50% or 75% JAK2V617F were generated, in which the production of IL-1β, IP-10 and RANTES was increased; other cytokines were not affected. Secondly, we searched for causes of chronic inflammation in MPNs other than driver mutations. Since antigen-driven selection is increasingly implicated in the pathogenesis of blood malignancies, we investigated whether proinflammatory glucosylsphingosine (GlcSph) may play a role in MPNs. We report that 20% (15/75) of MPN patients presented with anti-GlcSph IgGs, distinguished by elevated levels of 11 cytokines. In summary, only IL-1β and IP-10 were linked to JAK2V617F both in patients and in UT-7 cells; other inflammation-linked cytokines in excess in MPNs were not. For subsets of MPN patients, a possible cause of inflammation may be auto-immunity against glucolipids.

Calreticulin in phagocytosis and cancer: opposite roles in immune response outcomes

Calreticulin (CRT) is a pleiotropic and highly conserved molecule that is mainly localized in the endoplasmic reticulum. Recently, CRT has gained special interest for its functions outside the endoplasmic reticulum where it has immunomodulatory properties. CRT translocation to the cell membrane serves as an "eat me" signal and promotes efferocytosis of apoptotic cells and cancer cell removal with completely opposite outcomes. Efferocytosis results in a silenced immune response and homeostasis, while removal of dying cancer cells brought about by anthracycline treatment, ionizing-irradiation or photodynamic therapy results in immunogenic cell death with activation of the innate and adaptive immune responses. In addition, CRT impacts phagocyte activation and cytokine production. The effects of CRT on cytokine production depend on its conformation, species specificity, degree of oligomerization and/or glycosylation, as well as its cellular localization and the molecular partners involved. The controversial roles of CRT in cancer progression and the possible role of the CALR gene mutations in myeloproliferative neoplasms are also addressed. The release of CRT and its influence on the different cells involved during efferocytosis and immunogenic cell death points to additional roles of CRT besides merely acting as an "eat me" signal during apoptosis. Understanding the contribution of CRT in physiological and pathological processes could give us some insight into the potential of CRT as a therapeutic target.

Calreticulin Blockade Attenuates Murine Acute Lung Injury by Inducing Polarization of M2 Subtype Macrophages

Calreticulin (CALR) has anti-tumor effects by increasing dendritic cell maturation and tumor antigen presentation. However, whether CALR affects macrophages and modulates progression of acute respiratory distress syndrome/acute lung injury (ARDS/ALI) remains unknown. In this study, we discovered that CALR protein was highly expressed in the mice with LPS-induced ALI and CALR expression level was positively correlated to the severity of ALI. Commercial anti-CALR antibody (aCALR) can neutralize recombinant CALR (rCALR) and suppress the expression of TNF-alpha and IL-6 in the rCALR-treated macrophages. Blocking CALR activity by intraperitoneal (i.p.) administration of aCALR significantly suppressed ALI, accompanied with lower total cell counts, neutrophil and T cell infiltration in bronchoalveolar lavage (BAL) and lung tissues. The expression of CXCL15, IL-6, IL-1beta, TNF-alpha, and CALR were significantly reduced, in association with more polarization of Siglec F+CD206+M2 subtype macrophages in the aCALR-treated mice. Pre-depletion of circulating monocytes did not abolish the aCALR-mediated suppression of ALI. Further analysis in bone marrow-derived macrophages (BMDMs) showed that aCALR suppressed the expression of CD80, IL-6, IL-1beta, IL-18, NLRP3, and p-p38 MAPK; but enhanced the expression of CD206 and IL-10. In addition, we observed more expression and phosphorylation of STAT6 in the aCALR-treated BMDM. Lack of STAT6 resulted in comparable and slightly higher expression of CALR, TNF-alpha and IL-6 in the aCALR-treated STAT6-/- BMDMs than the untreated cells. Therefore, we conclude that CALR is a novel biomarker in the evaluation of ALI. Blocking CALR activity by aCALR effectively suppressed ALI independent of circulating monocytes. Siglec F+CD206+M2 subtype macrophages and p38 MAPK/STAT6 signaling pathway played important role in the immune regulation of aCALR. Blocking CALR activity is a promising therapeutic approach in the treatment of ARDS/ALI.

Emerging Therapeutic Targets in Oncologic Photodynamic Therapy

Background:

Reactive oxygen species sustain tumorigenesis and cancer progression through deregulated redox signalling which also sensitizes cancer cells to therapy. Photodynamic therapy (PDT) is a promising anti-cancer therapy based on a provoked singlet oxygen burst, exhibiting a better toxicological profile than chemo- and radiotherapy. Important gaps in the knowledge on underlining molecular mechanisms impede on its translation towards clinical applications.

Aims and Methods:

The main objective of this review is to critically analyse the knowledge lately gained on therapeutic targets related to redox and inflammatory networks underlining PDT and its outcome in terms of cell death and resistance to therapy. Emerging therapeutic targets and pharmaceutical tools will be documented based on the identified molecular background of PDT.

Results:

Cellular responses and molecular networks in cancer cells exposed to the PDT-triggered singlet oxygen burst and the associated stresses are analysed using a systems medicine approach, addressing both cell death and repair mechanisms. In the context of immunogenic cell death, therapeutic tools for boosting anti-tumor immunity will be outlined. Finally, the transcription factor NRF2, which is a major coordinator of cytoprotective responses, is presented as a promising pharmacologic target for developing co-therapies designed to increase PDT efficacy.

Conclusion:

There is an urgent need to perform in-depth molecular investigations in the field of PDT and to correlate them with clinical data through a systems medicine approach for highlighting the complex biological signature of PDT. This will definitely guide translation of PDT to clinic and the development of new therapeutic strategies aimed at improving PDT.

Immunopathogenic Mechanisms and Novel Immune-Modulated Therapies in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, inflammatory autoimmune disease of unknown etiology. It is characterized by the presence of rheumatoid factor and anticitrullinated peptide antibodies. The orchestra of the inflammatory process among various immune cells, cytokines, chemokines, proteases, matrix metalloproteinases (MMPs), and reactive oxidative stress play critical immunopathologic roles in the inflammatory cascade of the joint environment, leading to clinical impairment and RA. With the growing understanding of the immunopathogenic mechanisms, increasingly novel marked and potential biologic agents have merged for the treatment of RA in recent years. In this review, we focus on the current understanding of pathogenic mechanisms, highlight novel biologic disease-modifying antirheumatic drugs (DMRADs), targeted synthetic DMRADs, and immune-modulating agents, and identify the applicable immune-mediated therapeutic strategies of the near future. In conclusion, new therapeutic approaches are emerging through a better understanding of the immunopathophysiology of RA, which is improving disease outcomes better than ever.

The Biophysical Interaction of the Danger-Associated Molecular Pattern (DAMP) Calreticulin with the Pattern-Associated Molecular Pattern (PAMP) Lipopolysaccharide

The endoplasmic reticulum (ER) chaperone protein, calreticulin (CRT), is essential for proper glycoprotein folding and maintaining cellular calcium homeostasis. During ER stress, CRT is overexpressed as part of the unfolded protein response (UPR). In addition, CRT can be released as a damage-associated molecular pattern (DAMP) molecule that may interact with pathogen-associated molecular patterns (PAMPs) during the innate immune response. One such PAMP is lipopolysaccharide (LPS), a component of the gram-negative bacterial cell wall. In this report, we show that recombinant and native human placental CRT strongly interacts with LPS in solution, solid phase, and the surface of gram-negative and gram-positive bacteria. Furthermore, LPS induces oilgomerization of CRT with a disappearance of the monomeric form. The application of recombinant CRT (rCRT) to size exclusion and anion exchange chromatography shows an atypical heterogeneous elution profile, indicating that LPS affects the conformation and ionic charge of CRT. Interestingly, LPS bound to CRT is detected in sera of bronchiectasis patients with chronic bacterial infections. By ELISA, rCRT dose-dependently bound to solid phase LPS via the N- and C-domain globular head region of CRT and the C-domain alone. The specific interaction of CRT with LPS may be important in PAMP innate immunity.

Immunogenic Apoptosis as a Novel Tool for Anticancer Vaccine Development

Immunogenic apoptosis, or more appropriately called immunogenic cell death (ICD), is a recently described form of apoptosis induced by a specific set of chemotherapeutic drugs or by physical therapeutic modalities, such as ionizing irradiation and photodynamic therapy. The peculiar characteristic of ICD is the ability to favor recognition and elimination of dying tumor cells by phagocytes in association with the release of pro-inflammatory molecules (such as cytokines and high-mobility group box-1). While in vitro and animal models pointed to ICD as one of the molecular mechanisms mediating the clinical efficacy of some anticancer agents, it is hard to clearly demonstrate its contribution in cancer patients. Clinical evidence suggests that the induction of ICD alone is possibly not sufficient to fully subvert the immunosuppressive tumor microenvironment. However, interesting results from recent studies contemplate the exploitation of ICD for improving the immunogenicity of cancer cells to use them as an antigen cargo in the development of dendritic cell (DC) vaccines. Herein, we discuss the effects of danger signals expressed or released by cancer cells undergoing ICD on the maturation and activation of immature and mature DC, highlighting the potential added value of ICD in adoptive immunotherapy protocols.

Endogenous DAMPs, Category I: Constitutively Expressed, Native Molecules (Cat. I DAMPs)

This chapter provides the reader with a collection of endogenous DAMPs in terms of constitutively expressed native molecules. The first class of this category refers to DAMPs, which are passively released from necrotic cells, and includes the most prominent subclasses of high mobility group box I and heat shock proteins. Further subclasses of DAMPs that are passively released from necrotic cells include S100 proteins, nucleic acids, histones, pro-forms of interleukin-1-family members, mitochondria-derived N-formylated peptides, F-actin, and heme. A particular subclass of these passively released DAMPs are molecules, which indirectly activate the inflammasome, including adenosine-5′-triphosphate, monosodium urate crystals, cholesterol crystals, some lipolytic species, and beta-amyloid. All these passively released DAMPs are characterized by their capability to promote necroinflammatory responses. The second class of this Category I refers to molecules, which are exposed on the surface of stressed cells. They include the subclass of phagocytosis-facilitating molecules such as calreticulin, as well as the subclass of MHC-I-related molecules such as MHC-I-related molecule A and B. These DAMPs are capable of inducing the activation of innate lymphoid cells and unconventional T cells. One of these DAMPs, the major histocompatibility complex I-related molecule A, is shown to act as a bona fide transplantation antigen. In sum, the endogenous constitutively expressed native molecules represent an impressive category of DAMPs with extraordinary properties, which play a critical role in the pathogenesis of many human diseases.

Calreticulin Fragment 39-272 Promotes B16 Melanoma Malignancy through Myeloid-Derived Suppressor Cells In Vivo

Calreticulin (CRT), a multifunctional Ca²⁺-binding glycoprotein mainly located in the endoplasmic reticulum, is a tumor-associated antigen that has been shown to play protective roles in angiogenesis suppression and anti-tumor immunity. We previously reported that soluble CRT (sCRT) was functionally similar to heat shock proteins or damage-associated molecular patterns in terms of ability to activate myeloid cells and elicit strong inflammatory cytokine production. In the present study, B16 melanoma cell lines expressing recombinant CRT fragment 39-272 (sCRT/39-272) in secreted form (B16-CRT), or recombinant enhanced green fluorescence protein (rEGFP) (B16-EGFP), were constructed for investigation on the roles of sCRT in tumor development. When s.c. inoculated into C57BL/6 mice, the B16-CRT cells were significantly more aggressive (in terms of solid tumor growth rate) than B16-EGFP controls in a TLR4- and myeloid-derived suppressor cells (MDSC)-dependent manner. The B16-CRT-bearing mice showed increased Gr1⁺ MDSC infiltration in tumor tissues, accelerated proliferation of CD11b⁺Ly6G⁺Ly6C^low (G-MDSC) precursors in bone marrow, and higher percentages of G-MDSCs in spleen and blood, which was mirrored by decreased percentage of dendritic cells (DC) in periphery. In in vitro studies, recombinant sCRT/39-272 was able to promote migration and survival of tumor-derived MDSCs via interaction with TLR4, inhibit MDSC differentiation into DC, and also elicit expression of inflammatory proteins S100A8 and S100A9 which are essential for functional maturation and chemotactic migration of MDSCs. Our data provide solid evidence for CRT as a double-edged sword in tumor development.

The humanized anti-human AMHRII mAb 3C23K exerts an anti-tumor activity against human ovarian cancer through tumor-associated macrophages

Müllerian inhibiting substance, also called anti-Müllerian hormone (AMH), inhibits proliferation and induces apoptosis of AMH type II receptor-positive tumor cells, such as human ovarian cancers (OCs). On this basis, a humanized glyco-engineered monoclonal antibody (3C23K) has been developed. The aim of this study was therefore to experimentally confirm the therapeutic potential of 3C23K in human OCs. We first determined by immunofluorescence, immunohistochemistry and cytofluorometry analyses the expression of AMHRII in patient’s tumors and found that a majority (60 to 80% depending on the detection technique) of OCs were positive for this marker. We then provided evidence that the tumor stroma of OC is enriched in tumor-associated macrophages and that these cells are responsible for 3C23K-induced killing of tumor cells through ADCP and ADCC mechanisms. In addition, we showed that 3C23K reduced macrophages induced-T cells immunosuppression. Finally, we evaluated the therapeutic efficacy of 3C23K alone and in combination with a carboplatin-paclitaxel chemotherapy in a panel of OC Patient-Derived Xenografts. In those experiments, we showed that 3C23K significantly increased the proportion and the quality of chemotherapy-based in vivo responses. Altogether, our data support the potential interest of AMHRII targeting in human ovarian cancers and the evaluation of 3C23K in further clinical trials.

Association of calreticulin expression with disease activity and organ damage in systemic lupus erythematosus patients

Measurement of disease activity in patients with systemic lupus erythematosus (SLE) is important for monitoring disease progression and evaluating the therapeutic effects. The severity of organ damage correlates with clinical status and prognosis. Therefore, it is imperative to find an effective biomarker measuring disease activity and organ damage for SLE management. The present study investigated the possibility of serum calreticulin (CRT) in the assessment of disease activity and organ damage in SLE patients. Serum CRT levels from 80 patients with SLE, 55 patients with other autoimmune diseases and 60 healthy controls (HC) were measured by ELISA. Disease activity was assessed using the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) scores. Organ damage was evaluated with the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index. CRT levels in SLE were significantly higher than that in other autoimmune diseases and HC. CRT was correlated with SLEDAI-2K score (r=0.3345, P=0.0024), and with anti-double-stranded DNA (anti-dsDNA) (r=0.4483, P<0.0001). A significant negative correlation of CRT levels with complement 3 (r=-0.3635, P=0.0009) and complement 4 (r=-0.3507, P=0.0014) was observed in patients with SLE. Furthermore, the patients with SLE and a positive anti-Ro52 result had higher levels of CRT compared with those with a negative anti-Ro52 result (P<0.001). Elevated levels of CRT were also reported among patients with SLE who also indicated the presence of cumulative organ damage. In addition, increased expression of CRT correlated with the presence of lupus nephritis. In conclusion, the results of the current report provided that CRT may be used as a potential biomarker for clinical diagnosis and of prognosis, providing additional information regarding disease activity and organ damage alongside other traditional indices.

Serum calreticulin as a novel biomarker of juvenile idiopathic arthritis disease activity

OBJECTIVE

This study aimed to investigate the relations between calreticulin (CRT) serum level and both disease activity and severity parameters in juvenile idiopathic arthritis (JIA).

MATERIAL AND METHODS

In this study, 60 children with JIA and 50 age-and-sex-matched healthy subjects were enrolled. The assessment of the disease activity was done using juvenile arthritis disease activity score 27 (JADAS-27). The assessment of disease severity was done via gray-scale ultrasonography (US) and power Doppler US (PDUS). Enzyme-linked immunosorbent assay (ELISA) was used to assay the serum level of human CRT.

RESULTS

The mean serum CRT levels in JIA patients was 8.6±1.2 ng/mL and showed a highly significant increase (p=0.001) as compared to the mean serum levels in the controls (5.02±0.77 ng/mL). There were statistically significant positive correlations between the serum CRT levels and disease duration, tender joint count, swollen joint count, visual analog scale, erythrocyte sedimentation rate, JADAS-27, C-reactive protein, rheumatoid factor titer, and ultrasonographic grading for synovitis and neovascularization.

CONCLUSION

Elevated serum CRT levels in JIA patients and its correlations with JIA disease activity and severity parameters signified that CRT might be used as a novel biomarker for disease activity and severity in JIA.

Inactivation of p27kip1 Promoted Nonspecific Inflammation by Enhancing Macrophage Proliferation in Islet Transplantation

Islet transplantation suffers from low efficiency caused by nonspecific inflammation-induced graft loss after transplantation. This study reports increased islet loss and enhanced inflammatory response in p27-deficient mice (p27-/-) and proposes a possible mechanism. Compared with wild type, p27-/- mice showed more severe functional injury of islet, with increased serum levels of inflammatory cytokines IL-1 and TNF-α, inducing macrophage proliferation. Furthermore, the increased number, proapoptotic proteins, and nuclear factor-kappa b (NF-κB) phosphorylation status of the infiltrating macrophages were accompanied by increased TNF-α mRNA level of islet graft site in p27-/- mice. Moreover, in vitro, we found that macrophages were still activated and cocultured with islet and promoted islet loss even blocking the direct effect of TNF-α on islets. Malondialdehyde (MDA, an end product of lipid peroxidation) in islet and media were increased after cocultured with macrophages. p27 deficiency also increased macrophage proliferation and islet injury. Therefore, p27 inactivation promotes injury islet graft loss via the elevation of proliferation and inflammatory cytokines secretion in infiltrating macrophages which induced nonspecific inflammation independent of TNF-α/nuclear factor-kappa b pathway. This potentially represents a promising therapeutic target in improving islet graft survival.

Circulating Calreticulin Is Increased in Myelofibrosis: Correlation with Interleukin-6 Plasma Levels, Bone Marrow Fibrosis, and Splenomegaly

Myelofibrosis (MF) is a clonal neoplasia of the hemopoietic stem/progenitor cells associated with genetic mutations in the Janus kinase 2 (JAK2), myeloproliferative leukemia virus oncogene (MPL), and calreticulin (CALR) genes. MF is also characterized by a state of chronic inflammation. Calreticulin (CRT), as a multifunctional protein, is involved in a spectrum of cellular processes including inflammation, autoimmunity, and cancer initiation/progression. Based on this background, we hypothesised that in MF circulating CRT might reflect the inflammatory process. In the present study we show that circulating CRT is increased in MF patients compared to healthy controls. Also, in MF, CRT levels highly correlate with bone marrow fibrosis, splenomegaly, and Interleukin-6 (IL-6) plasma levels. In turn, higher IL-6 levels also correlated with disease severity in terms of increased spleen size, bone marrow fibrosis, number of circulating CD34⁺ cells, and lower hemoglobin values. These results demonstrate that the circulating CRT takes part in the inflammatory network of MF and correlates with aggressiveness of the disease.

Amniotic fluid calreticulin in pregnancies complicated by the preterm prelabor rupture of membranes

OBJECTIVE

This study aimed to determine the amniotic fluid calreticulin concentrations in women with the preterm prelabor rupture of membranes (PPROM) based on the microbial invasion of the amniotic cavity (MIAC), intraamniotic inflammation (IAI) and microbial-associated IAI.

METHODS

One hundred sixty-eight women with singleton pregnancies were included in this study. Amniotic fluid samples were obtained by transabdominal amniocentesis and were assayed for calreticulin concentrations by ELISA. IAI was defined as an amniotic fluid interleukin-6 concentration > 745 pg/ml. Microbial-associated IAI was defined as the presence of both MIAC and IAI.

RESULT

Women with MIAC (with MIAC: median 54.4 ng/ml, versus without MIAC: median 32.6 ng/ml; p < 0.0001), IAI (with IAI: median 66.8 ng/ml, versus without IAI: median 33.0 ng/ml; p < 0.0001) and microbial-associated IAI (with microbial-associated IAI: median 82.5 ng/ml, versus without microbial-associated IAI: median 33.7 ng/ml; p < 0.0001) had higher concentrations of calreticulin than women without these complications. An amniotic fluid calreticulin concentration of 81.4 ng/ml was found to be the best cutoff point for identifying women with microbial-associated IAI.

CONCLUSIONS

The presence of microbial-associated IAI is associated with increased amniotic fluid calreticulin concentrations. Calreticulin seems to be a promising marker for the early identification of PPROM complicated by microbial-associated IAI.

Imiquimod-induced apoptosis of melanoma cells is mediated by ER stress-dependent Noxa induction and enhanced by NF-κB inhibition

Melanoma is characterized by dysregulated intracellular signalling pathways including an impairment of the cell death machinery, ultimately resulting in melanoma resistance, survival and progression. This explains the tumour's extraordinary resistance to the standard treatment. Imiquimod is a topical immune response modifier (imidazoquinoline) with both antiviral and antitumour activities. The mechanism by which imiquimod triggers the apoptosis of melanoma cells has now been carefully elucidated. Imiquimod‐induced apoptosis is associated with the activation of apoptosis signalling regulating kinase1/c‐Jun‐N‐terminal kinase/p38 pathways and the induction of endoplasmic stress characterized by the activation of the protein kinase RNA‐like endoplasmic reticulum kinase signalling pathway, increase in intracellular Ca²⁺ release, degradation of calpain and subsequent cleavage of caspase‐4. Moreover, imiquimod triggers the activation of NF‐κB and the expression of the inhibitor of apoptosis proteins (IAPs) such as, X‐linked IAP (XIAP) together with the accumulation of reactive oxygen species (ROS). Also, imiquimod triggers mitochondrial dysregulation characterized by the loss of mitochondrial membrane potential (Δψm), the increase in cytochrome c release, and cleavage of caspase‐9, caspase‐3 and poly(ADP‐ribose) polymerase (PARP). Inhibitors of specific pathways, permit the elucidation of possible mechanisms of imiquimod‐induced apoptosis. They demonstrate that inhibition of NF‐kB by the inhibitor of nuclear factor kappa‐B kinase (IKK) inhibitor Bay 11‐782 or knockdown of XIAP induces melanoma apoptosis in cells exposed to imiquimod. These findings support the use of either IKK inhibitors or IAP antagonists as adjuvant therapies to improve the effectiveness topical imiquimod in the treatment of melanoma.

Pathogenesis of Myeloproliferative Neoplasms: Role and Mechanisms of Chronic Inflammation

Myeloproliferative neoplasms (MPNs) are a heterogeneous group of clonal diseases characterized by the excessive and chronic production of mature cells from one or several of the myeloid lineages. Recent advances in the biology of MPNs have greatly facilitated their molecular diagnosis since most patients present with mutation(s) in the JAK2, MPL, or CALR genes. Yet the roles played by these mutations in the pathogenesis and main complications of the different subtypes of MPNs are not fully elucidated. Importantly, chronic inflammation has long been associated with MPN disease and some of the symptoms and complications can be linked to inflammation. Moreover, the JAK inhibitor clinical trials showed that the reduction of symptoms linked to inflammation was beneficial to patients even in the absence of significant decrease in the JAK2-V617F mutant load. These observations suggested that part of the inflammation observed in patients with JAK2-mutated MPNs may not be the consequence of JAK2 mutation. The aim of this paper is to review the different aspects of inflammation in MPNs, the molecular mechanisms involved, the role of specific genetic defects, and the evidence that increased production of certain cytokines depends or not on MPN-associated mutations, and to discuss possible nongenetic causes of inflammation.

Proinflammatory Cytokine IL-6 and JAK-STAT Signaling Pathway in Myeloproliferative Neoplasms

The recent JAK1/2 inhibitor trial in myeloproliferative neoplasms (MPNs) showed that reducing inflammation can be more beneficial than targeting gene mutants. We evaluated the proinflammatory IL-6 cytokine and JAK-STAT signaling pathway related genes in circulating CD34⁺ cells of MPNs. Regarding laboratory data, leukocytosis has been observed in polycythemia vera (PV) and JAK2V617F mutation positive versus negative primary myelofibrosis (PMF) patients. Moreover, thrombocytosis was reduced by JAK2V617F allele burden in essential thrombocythemia (ET) and PMF. 261 significantly changed genes have been detected in PV, 82 in ET, and 94 genes in PMF. The following JAK-STAT signaling pathway related genes had augmented expression in CD34⁺ cells of MPNs: CCND3 and IL23A regardless of JAK2V617F allele burden; CSF3R, IL6ST, and STAT1/2 in ET and PV with JAK2V617F mutation; and AKT2, IFNGR2, PIM1, PTPN11, and STAT3 only in PV. STAT5A gene expression was generally reduced in MPNs. IL-6 cytokine levels were increased in plasma, as well as IL-6 protein levels in bone marrow stroma of MPNs, dependent on JAK2V617F mutation presence in ET and PMF patients. Therefore, the JAK2V617F mutant allele burden participated in inflammation biomarkers induction and related signaling pathways activation in MPNs.

Prognostic and Predictive Value of DAMPs and DAMP-Associated Processes in Cancer

It is now clear that human neoplasms form, progress, and respond to therapy in the context of an intimate crosstalk with the host immune system. In particular, accumulating evidence demonstrates that the efficacy of most, if not all, chemo- and radiotherapeutic agents commonly employed in the clinic critically depends on the (re)activation of tumor-targeting immune responses. One of the mechanisms whereby conventional chemotherapeutics, targeted anticancer agents, and radiotherapy can provoke a therapeutically relevant, adaptive immune response against malignant cells is commonly known as “immunogenic cell death.” Importantly, dying cancer cells are perceived as immunogenic only when they emit a set of immunostimulatory signals upon the activation of intracellular stress response pathways. The emission of these signals, which are generally referred to as “damage-associated molecular patterns” (DAMPs), may therefore predict whether patients will respond to chemotherapy or not, at least in some settings. Here, we review clinical data indicating that DAMPs and DAMP-associated stress responses might have prognostic or predictive value for cancer patients.

TNF Apoptosis Protection Fraction (TAPF) prevents apoptosis induced by TNF, but not by Fas or TRAIL, via NF-κB-induced increase in cFLIP

Tumor Necrosis Factor α (TNFα) induces both the apoptotic pathway and anti-apoptotic factors. Incubation of human dermal fibroblasts with TAPF (TNF Apoptosis Protection Fraction) protects them from apoptosis induced by the subsequent addition of TNF and cycloheximide (CHX). TAPF does not protect against apoptosis induced by CHX in combination with either TRAIL (TNF related apoptosis inducing ligand) or an agonistic Fas antibody, or against apoptosis induced by the chemotherapeutic agent doxorubicin. Incubation with TAPF does not affect the quantity of TNF that binds to the cell. TAPF prevents TNF-induced cleavage of caspases 8, 9, 3 and 7 and the apoptotic substrate PARP (poly-ADP ribose polymerase), but has no effect when these molecules are induced by an agonistic Fas antibody. TAPF induces rapid phosphorylation of the NF-κB/p65 (nuclear factor-κB) transcription factor at serine 536 which is indicative of its activation. TAPF increases the expression of cFLIP (cellular FLICE-inhibitory protein) which is a potent inhibitor of apoptosis that acts by preventing the cleavage of caspase 8. This increase in cFLIP is coincident with protection from TNF-induced apoptosis. Decreasing cFLIP levels using shRNA (short hairpin RNA) decreases protection by TAPF. TAPF also induced the anti-apoptotic A20 protein. These data indicate that TAPF protects human dermal fibroblasts from TNF-induced apoptosis by induction of cFLIP and subsequent inhibition of caspase 8 cleavage.

The ever-expanding immunomodulatory role of calreticulin in cancer immunity

Calreticulin is a pleiotropic molecule that normally resides in the lumen of the endoplasmic reticulum (ER). Here, it has various functions, ranging from regulation of calcium homeostasis to ensuring proper protein folding. More recently, calreticulin gained special interest for its extracellular functions, where it has direct immunomodulatory activity. In this respect, calreticulin activates dendritic cells and macrophages. In addition, certain anti-cancer therapies induce the translocation of calreticulin from the ER to the cell surface of dying cancer cells, where calreticulin dictates the immunogenicity of these cells. Interestingly, treatment with tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL) also induces membrane calreticulin exposure on cancer cells. As shown here, calreticulin directly interacts with TRAIL and its receptor-signaling complex, as well as with other TNF family members. Of note, TRAIL is a well known immunomodulatory molecule, and is expressed on the surface of natural killer T-cells. Therefore, calreticulin may have an as yet unrecognized wide(r) impact on immunity, with the TNF-ligand family modulating virtually all aspects of the immune response.

Fucoidan supplementation improves exercise performance and exhibits anti-fatigue action in mice

Fucoidan (FCD) is a well-known bioactive constituent of seaweed extract that possess a wide spectrum of activities in biological systems, including anti-cancer, anti-inflammation and modulation of immune systems. However, evidence on the effects of FCD on exercise performance and physical fatigue is limited. Therefore, we investigated the potential beneficial effects of FCD on ergogenic and anti-fatigue functions following physiological challenge. Male ICR mice from three groups (n = 8 per group) were orally administered FCD for 21 days at 0, 310 and 620 mg/kg/day, which were, respectively, designated the vehicle, FCD-1X and FCD-2X groups. The results indicated that the FCD supplementations increased the grip strength (p = 0.0002) and endurance swimming time (p = 0.0195) in a dose-depend manner. FCD treatments also produced dose-dependent decreases in serum levels of lactate (p < 0.0001) and ammonia (p = 0.0025), and also an increase in glucose level (p < 0.0001) after the 15-min swimming test. In addition, FCD supplementation had few subchronic toxic effects. Therefore, we suggest that long-term supplementation with FCD can have a wide spectrum of bioactivities on health promotion, performance improvement and anti-fatigue.