Effect of IL-15 on the secretion of IL-1beta, IL-1Ra and sIL-1RII by PMN from cancer patients

Interleukin-1 receptor antagonist: a promising cytokine against human squamous cell carcinomas

Inflammation, especially chronic inflammation, is closely linked to tumor development. As essential chronic inflammatory cytokines, the interleukin family plays a key role in inflammatory infections and malignancies. The interleukin-1 (IL-1) receptor antagonist (IL1RA), as a naturally occurring receptor antagonist, is the first discovered and can compete with IL-1 in binding to the receptor. Recent studies have revealed the association of the polymorphisms in IL1RA with an increased risk of squamous cell carcinomas (SCCs), including squamous cell carcinoma of the head and neck (SCCHN), cervical squamous cell carcinoma, cutaneous squamous cell carcinoma (cSCC), esophageal squamous cell carcinoma (ESCC), and bronchus squamous cell carcinoma. Here, we reviewed the antitumor potential of IL1RA as an IL-1-targeted inhibitor.

Innate Neutrophil Memory Dynamics in Disease Pathogenesis

Neutrophils, the most abundant leukocytes in circulation and the first responders to infection and inflammation, closely modulate both acute and chronic inflammatory processes. Resting neutrophils constantly patrol vasculature and migrate to tissues when challenges occur. When infection and/or inflammation recede, tissue neutrophils will be subsequently cleaned up by macrophages which collectively contribute to the resolution of inflammation. While most studies focus on the anti-microbial function of neutrophils including phagocytosis, degranulation, and neutrophil extracellular traps (NETs) formation, recent research highlighted additional contributions of neutrophils beyond simply controlling infectious agents. Neutrophils with resolving characteristics may alter the activities of neighboring cells and facilitate inflammation resolution, modulate long-term macrophage and adaptive immune responses, therefore having important impacts on host pathophysiology. The focus of this chapter is to provide an updated assessment of recent progress in the emerging field of neutrophil programming and memory in the context of both acute and chronic diseases.

Multiple Phenotypic Changes Define Neutrophil Priming

Exposure to pro-inflammatory cytokines, chemokines, mitochondrial contents, and bacterial and viral products induces neutrophils to transition from a basal state into a primed one, which is currently defined as an enhanced response to activating stimuli. Although, typically associated with enhanced generation of reactive oxygen species (ROS) by the NADPH oxidase, primed neutrophils show enhanced responsiveness of exocytosis, NET formation, and chemotaxis. Phenotypic changes associated with priming also include activation of a subset of functions, including adhesion, transcription, metabolism, and rate of apoptosis. This review summarizes the breadth of phenotypic changes associated with priming and reviews current knowledge of the molecular mechanisms behind those changes. We conclude that the current definition of priming is too restrictive. Priming represents a combination of enhanced responsiveness and activated functions that regulate both adaptive and innate immune responses.

Soluble IL-1 decoy receptor is associated with gastric adenocarcinoma

Background:

In recent years, studies on gastric cancer include changes in cancer associated immune system activation and the levels of immune system markers. It has been demonstrated that TNF-α (tumor necrosis factor-alpha) and IL-6 (interleukin-6) play a role in inflammatory associated carcinogenesis.

Objective:

Our aim was to investigate serum soluble IL-1 decoy receptor (sIL- 1RII), TNF-α and IL-6 levels in gastric adenocarcinoma patients.

Materials and methods:

Male gastric adenocarcinoma patients and dyspeptic participants, in total 55 cases were included. Serum sIL-1RII, TNF-α and IL-6 concentrations were measured.

Results:

The median sIL-1RII levels of the patients were statistically significantly lower than the median of the control group (3111 ng/mL; 3601 ng/mL, respectively) (p=0.003). But the median TNF-α and IL-6 levels (58.17 ng/mL; 10.22 ng/mL, respectively) were both numerically higher than those of control group levels (16.62 ng/mL; 5.74 ng/mL, respectively). Also, patients’ median TNF-α levels were found statistically significantly higher (p=0.034).

Conclusion:

This study showed the increase of TNF-α, IL-6 levels and for the first time the decrease of sIL-1RII in gastric cancer patients. We propose that negative regulation of gastric cancer using sIL-1RII could be a new anti-cancer strategy.

General significance:

Our study provides target pathways for further studies in the pathophysiology of gastric cancer.

Expression of IL-1 and IL-6 and their natural regulators in leukocytes of B-cell chronic lymphocytic leukaemia patients

PURPOSE

The purpose of the study was the assessment of the expression of IL-1β and IL-6, and the proteins regulating their biological activity, namely IL-1RII, IL-1Ra, as well as sIL-6Rα, sgp-130 in leukemic lymphocytes and autologous neutrophils of B-CLL patients.

MATERIAL/METHODS

The study involved a group of B-cell chronic lymphocytic leukemia patients and healthy volunteer blood donors. The presence of chosen proteins and their natural regulators was confirmed by Western blot.

RESULTS

Western blot analysis showed a decreased expression of IL-1β and IL-6 in the leukocytes of B-CLL patients. Decreased expression of sIL-6Rα has been observed in lymphocytes, with a simultaneous increase of expression in PMNs. Lower expression of sgp-130 was found in B cells while its expression was elevated in the neutrophils of patients in early stages of the disease.

CONCLUSIONS

The changes observed in the expression of IL-1 and IL-6 seem to exclude their immediate involvement in the progress of B-CLL. However, the presented changes in the expression of proteins regulating IL-1β and IL-6 in PMNs indicate a potential role of early immune response cells also in advanced stages of the disease.

Neutrophils and granulocytic myeloid-derived suppressor cells: immunophenotyping, cell biology and clinical relevance in human oncology

Accumulating evidence indicates that myeloid cells are critically involved in the pathophysiology of human cancers. In contrast to the well-characterized tumor-associated macrophages, the significance of granulocytes in cancer has only recently begun to emerge. A number of studies found increased numbers of neutrophil granulocytes and granulocytic myeloid-derived suppressor cells (GrMDSCs) both in the peripheral blood and in the tumor tissues of patients with different types of cancer. Most importantly, granulocytes have been linked to poor clinical outcome in cancer patients which suggests that these cells might have important tumor-promoting effects. In this review, we will address in detail the following major topics: (1) neutrophils and GrMDSCs in the peripheral blood of cancer patients-phenotype and functional changes; (2) neutrophils and GrMDSCs in the tumor tissue-potential mechanisms of tumor progression and (3) relevance of neutrophils and GrMDSCs for the clinical outcome of cancer patients. Furthermore, we will discuss the advantages and disadvantages of the current strategies used for identification and monitoring of human MDSCs. We propose a six-color immunophenotyping protocol that discriminates between monocytic MDSCs (MoMDSCs), two subsets of GrMDSCs and two subsets of immature myeloid cells in human cancer patients, thus, allowing for an improved characterization and understanding of these multifaceted cells.

Interleukin-15 increases neutrophil adhesion onto human respiratory epithelial A549 cells and attracts neutrophils in vivo

Interleukin-15 (IL-15) is a neutrophil agonist that plays a role in inflammatory disorders, including a variety of pulmonary diseases. Adhesion of neutrophils onto pulmonary cells is a major event leading to development of inflammation. Recently, elevated levels of IL-15 have been associated with different pulmonary diseases. There is no clear evidence that IL-15 modulates cell surface expression of adhesion molecules in neutrophils, or that IL-15 is involved in neutrophil adhesion onto pulmonary cells. Also, it is not clear if IL-15 induces a neutrophilic inflammation in vivo. This study was aimed at elucidation of these issues. Neutrophils were treated with IL-15 and cell surface expression of CD11a, CD11b, CD11c and CD18 was monitored by flow cytometry. The human respiratory epithelial A549 cell line was used as a substrate for the neutrophil adhesion assay and cell surface expression of CD50, CD54 and CD106 was monitored in IL-15-induced A549 cells. The murine air pouch model was used for investigating potential neutrophilic inflammation induced by IL-15 in vivo. IL-15 significantly increased neutrophil cell surface expression of CD11b and CD18 and up-regulated A549 cell surface expression of CD54. Moreover, A549 cells were found to express IL-15R components and adhesion of neutrophils onto A549 cells was increased when neutrophils or A549 cells were treated with IL-15. Finally, IL-15 induced neutrophilic inflammation in vivo and concentrations of IL-6 and CXCL2/MIP-2 were increased in IL-15-induced pouches. IL-15 might participate in inflammatory pulmonary diseases by attracting neutrophils, modulating cell surface expression molecules and increasing neutrophil adhesion onto pulmonary cells.

Cloning and expression of rabbit interleukin-15

In order to understand the inflammatory mechanisms related to rabbit interleukin-15 (RIL-15), we cloned and expressed RIL-15 cDNA gene. A cDNA encoding RIL-15 was cloned from heart mRNA by reverse transcriptase polymerase chain reaction (RT-PCR) amplification using hIL-15 primers. The RIL-15 cDNA contains an open reading frame (ORF) of 162 amino acids (aa) with a 48 aa leader sequence. The predicted molecular weight of the encoded protein (12.5 kDa) matched the size of recombinant IL-15 on Western blotting in an Escherichia coli (pET32a) expression system. Amino acid and nucleotide sequence analyses of RIL-15 revealed 82.7% and 87% homology with human IL-15 (hIL-15), respectively. RIL-15 is similar to the hIL-15 (hIL-15) in that it contains seven cysteine residues. RT-PCR showed that IL-15 is expressed in many tissues in the rabbit, including heart, spleen, lung, liver, muscle and kidney. Expressed and purified recombinant RIL-15, in the absence of the 48 aa leader sequence, stimulated the proliferation of cells of the mouse T cell line, CTLL-2, and its activity is comparable to hIL-15. Western blotting demonstrated that recombinant RIL-15 can be recognized by anti-IL-15 neutralization antibody. Western blotting also confirmed that IL-15 is present in many tissues including heart, spleen, lung, liver, muscle and kidney.

Interleukin-15 enhances human neutrophil phagocytosis by a Syk-dependent mechanism: importance of the IL-15Rα chain

Interleukin-15 (IL-15) is a cytokine that possesses interesting, potential therapeutic properties. However, based on several parameters including activation of neutrophils, it is also recognized as a proinflammatory cytokine. The mechanisms by which IL-15 activates human neutrophil functions are not fully understood. Although these cells express a functional IL-15 receptor (IL-15R) composed of IL-15Ralpha, IL-2/15Rbeta (CD122), and gamma(c) (CD132) subunits, the role of each receptor component has not been investigated in IL-15-induced human neutrophil responses. In the present study, fluorescein-activated cell sorter analysis revealed that the ability of IL-15 to enhance neutrophil phagocytosis is not a result of increased expression of IL-15Ralpha, CD122, or CD132 on the neutrophil cell surface. Pretreatment of neutrophils with specific antibodies to IL-15Ralpha, CD122, or CD132 was found to inhibit phagocytosis of opsonized-sheep red blood cells by nearly 40%, 21%, and 27%, respectively. As expected, pretreatment of neutrophils with anti-IL-2Ralpha (CD25) had no effect. Pretreatment of cells with the Syk inhibitor piceatannol was found to significantly inhibit the ability of IL-15 to enhance phagocytosis. In addition, IL-15 was found to induce tyrosine phosphorylation of Syk that was largely inhibited by pretreating cells with piceatannol. Moreover, we found that Syk kinase is physically associated with IL-15Ralpha. We conclude that IL-15R enhances neutrophil phagocytosis by a Syk-dependent mechanism and that the IL-15Ralpha chain plays a key role in mediating this response, at least by interacting with Syk kinase.

Interleukin-15 delays human neutrophil apoptosis by intracellular events and not via extracellular factors: role of Mcl-1 and decreased activity of caspase-3 and caspase-8

Interleukin-15 (IL-15) induces the de novo protein synthesis of intracellular polypeptides and delays neutrophil apoptosis by a mechanism that is still unclear. Herein, we investigated the potential antiapoptotic role of newly synthesized proteins released into the external milieu in IL-15-induced neutrophils. We found that IL-15 induces the de novo synthesis of an approximately 23-kDa protein, representing the predominant protein detected in the milieu, and identified it as IL-1 receptor antagonist (IL-1Ra) by Western blot and immunoprecipitation. We quantified IL-1Ra, IL-1alpha, and IL-1beta concentrations by enzyme-linked immunosorbent assay in intracellular and extracellular fractions from IL-15-induced neutrophils and found that IL-15 does not increase IL-1alpha or IL-1beta production but induces IL-1Ra release. Also, we demonstrated that IL-1Ra does not modulate apoptosis, even at a concentration 250 times greater than that measured in the external milieu. In contrast to granulocyte macrophage-colony stimulating factor, the supernatant harvested from IL-15-induced neutrophils was devoid of antiapoptotic activity. Addition of cycloheximide demonstrates that IL-15 delays apoptosis via de novo synthesis of intracellular proteins and that it increases myeloid cell differentiation factor-1 stability. We demonstrated also that IL-15 decreases the activity of caspase-3 and caspase-8, resulting in an inhibition of vimentin cleavage. Our results indicate that IL-15 can activate an anti-inflammatory loop, based on its ability to induce the synthesis of IL-1Ra by neutrophils. We conclude that IL-15 delays human neutrophil apoptosis by intracellular events and not via extracellular factors.

Role of interleukin-15 and interleukin-18 in the secretion of sIL-6R and sgp130 by human neutrophils

BACKGROUND

Available data indicate that neutrophils (PMN) produce a wide range of cytokines with the potential to modulate immune response. Recent investigation have shown that interleukin (IL)-15 and IL-18 potentiated several functions of normal neutrophils. It has been reported that IL-18-induced cytokine production may be significantly enhanced by coincident addition of IL-15.

AIMS

In the present study we compared the effect of recombinant human (rh)IL-15 and rhIL-18 as well as effect of a rhIL-15 and rhIL-18 combination on the induction secretion of sIL-6Ralpha and sgp130 by human neutrophils.

METHODS

PMN were isolated from heparinized whole blood of healthy persons. The PMN were cultured for 18 h at 37 degrees C in a humidified incubator with 5% CO(2). rhIL-15 and/or rhIL-18 and lipopolysaccharide were tested to PMN stimulation. The culture supernatants of PMN were removed and examined for the presence of sIL-6R and sgp130 by human enzyme-linked immunosorbent assay kits. Cytoplasmic protein fractions of PMN were analysed for the presence of sIL-6R and sgp130 by western blotting using monoclonal antibodies capable of detecting these proteins. Cells were lysed and cytoplasmic proteins were electrophoresed on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The resolved proteins were transferred onto nitrocellulose and incubated with the primary monoclonal antibodies anti-sIL-6R and anti-sgp130. The membranes were incubated at room temperature with alkaline phosphatase anti-mouse immunoglobulin G. Immunoreactive protein bans were visualized by an AP Conjugate Substrate Kit.

RESULTS AND CONCLUSIONS

The results of our investigation revealed that IL-15 alone, similarly to IL-18, has no significant ability for the regulation of both soluble IL-6 receptors, sIL-6R and sgp130, released by human neutrophils. It is interesting to note that the secretion of sgp130 was changed after PMN stimulation with rhIL-15 in the presence of rhIL-18. The combination of rhIL-15 and rhIL-18 was shown to induce PMN to secretion relatively higher amounts of sgp130 compared with the stimulation of PMN with rhIL-15 alone and rhIL-18 alone. The results obtained suggest that IL-15 and IL-18, belonging to the inflammatory cytokines, through the regulation of sgp130 secretion must be also considered as anti-inflammatory mediators that may influence the balance reactions mediated by the IL-6 cytokine family.