A phase 2 study of polatuzumab vedotin + bendamustine + rituximab in relapsed/refractory diffuse large B-cell lymphoma.

Polatuzumab vedotin (pola) is a CD79b-targeted antibody-drug conjugate delivering a potent antimitotic agent (monomethyl auristatin E) to B cells. This was an open-label, single-arm study of pola 1.8 mg/kg, bendamustine 90 mg/m2 , rituximab 375 mg/m2 (pola + BR) Q3W for up to six cycles in patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) who received ≥1 prior line of therapy and were ineligible for autologous stem cell transplantation (ASCT) or experienced treatment failure with prior ASCT. Primary endpoint was complete response rate (CRR) at the end of the treatment (EOT) by positron emission tomography-computed tomography (PET-CT) using modified Lugano Response Criteria. Secondary endpoints included efficacy, safety, and pharmacokinetics. Thirty-five patients (median age 71 [range 46-86] years) were enrolled. Twenty-three (66%) patients had refractory disease, and 23 (66%) had ≥2 prior lines of therapy. At a median follow-up of 5.4 (0.7-11.9) months, patients received a median of five treatment cycles. CRR was 34.3% (95% confidence interval [CI] 19.1-52.2) at EOT. Overall response rate was 42.9% at EOT, and median progression-free survival was 5.2 months (95% CI 3.6-not evaluable). Median overall survival was not reached. No fatal adverse events (AEs) were observed. Grade 3-4 AEs were mainly hematological: anemia (37%), neutropenia (31%), white blood cell count decreased (23%), thrombocytopenia/platelet count decreased/neutrophil count decreased (20% each), and febrile neutropenia (11%). Grade 1-2 peripheral neuropathy (PN; sensory and/or motor) was reported in 14% of patients; there were no ≥grade 3 PN events. This study (JapicCTI-184048) demonstrated the efficacy and safety of pola + BR in Japanese patients with R/R DLBCL who were ineligible for ASCT.

Discriminating phenotypic signatures identified for tocilizumab, adalimumab, and tofacitinib monotherapy and their combinations with methotrexate.

BACKGROUND: Clinical trials have shown combinations of anti-tumor necrosis factor biologicals plus methotrexate (MTX) are more effective treatments for rheumatoid arthritis than biological monotherapies, based, in part, on the assumption that MTX reduces the immunogenicity of biologicals. However, co-treatment with the anti-interleukin-6 receptor-alpha antibody tocilizumab (TCZ) and MTX does not demonstrate the same level of incremental benefit over TCZ monotherapy. Using the human primary cell based BioMAP phenotypic profiling platform, we investigated the impact of TCZ, adalimumab (ADA), and the small molecule drug tofacitinib (TOF), alone and in combination with MTX, on translational biomarkers that could indicate unique pharmacodynamic interactions outside those of reduced immunogenicity. METHODS: TCZ, ADA, and TOF, alone and in combination with MTX, were profiled in BioMAP systems at concentrations close to clinical exposure levels: TCZ, 200 µg/ml; TOF1, 1.1 µM; TOF2, 0.12 µM; MTX, 10 µM. Changes in biomarkers were evaluated by statistical methods to determine whether combinations differed from the individual agents. RESULTS: Although the BioMAP activity profile for TCZ + MTX was not significantly different from that for TCZ alone, profiles for ADA + MTX and TOF1 + MTX or TOF2 + MTX had a greater number of statistically significant different activities (P < 0.01) than did agents profiled individually. CONCLUSIONS: These data support the comparable efficacy of TCZ as monotherapy and as combination therapy and suggest that TOF, like ADA, may be more beneficial in combination with MTX. Taking an orthogonal approach to directly compare monotherapy and combination therapies indicates that MTX contributes to the efficacy of some, but not all, RA therapies and can be affected by factors additional to reduced immunogenicity.

Anti-interleukin-6 receptor antibody prevents systemic bone mass loss via reducing the number of osteoclast precursors in bone marrow in a collagen-induced arthritis model.

Systemic bone loss is a hallmark of rheumatoid arthritis (RA). Inflammatory cytokines such as interleukin (IL)-6 promote bone resorption by osteoclasts. Sphingosine-1-phosphate (S1P) controls the migration of osteoclast precursor cells (OCPs) between the blood and bone marrow, in part via S1P receptors (S1PR1 and S1PR2) expressed on the surface of OCPs. OCPs (CD11b(+) Gr-1(low+med) ) isolated from bone marrow of DBA/1J mice were stimulated with IL-6. S1P-directed chemotaxis of OCPs was evaluated using a transwell plate. mRNA expression of S1PR1 and S1PR2 was measured. DBA/1J mice were immunized with bovine type II collagen (days 0 and 21) and anti-mouse IL-6 receptor antibody (MR16-1) was administered on days 0 and/or 21. Trabecular bone volume was analysed using micro-computed tomography. The percentage of OCPs in tibial bone marrow and S1PR1 and S1PR2 mRNA expression in OCPs were measured. IL-6 stimulation significantly decreased S1P-directed chemotaxis of OCPs. IL-6 induced S1PR2 mRNA expression, but not S1PR1 mRNA expression, in OCPs. Bone volume was significantly lower in arthritic mice than in non-arthritic control mice on day 35. Treatment of immunized mice with MR16-1 significantly inhibited bone loss. In MR16-1-treated mice, the percentage of OCPs and expression of S1PR2 mRNA was each decreased compared with arthritic mice on day 14, but not on day 35. IL-6 increased the number of OCPs in tibial bone marrow via up-regulating S1PR2, thus playing a crucial role in systemic bone loss induced by inflammation.

Atherogenic effects of TNF-α and IL-6 via up-regulation of scavenger receptors.

Patients with chronic inflammatory disorders such as rheumatoid arthritis (RA) have a high risk of developing cardiovascular disease. We evaluated the effects of TNF-α and IL-6 on foam cell formation, a pivotal process in atherogenesis. Accumulation of intracellular oxidized LDL (oxLDL) was induced when THP-1/macrophages were stimulated with TNF-α or IL-6. TNF-α induced the expressions of scavenger receptors SR-A and LOX-1, and IL-6 induced SR-A expression. Inhibition of the NF-κB signaling markedly decreased TNF-α-induced foam cell formation and SR-A expression. Serum from RA patients, but not healthy subjects, induced foam cell formation, which was partially reversed by either IL-6 or TNF-α blockade in conjunction with inhibiting the induction of scavenger receptors. The present study clearly showed that in patients with chronic inflammation mediated by TNF-α and IL-6, these cytokines are directly implicated in atherosclerotic plaque formation.

IL-6/IL-6 receptor system and its role in physiological and pathological conditions.

IL (interleukin)-6, which was originally identified as a B-cell differentiation factor, is a multifunctional cytokine that regulates the immune response, haemopoiesis, the acute phase response and inflammation. IL-6 is produced by various types of cell and influences various cell types, and has multiple biological activities through its unique receptor system. IL-6 exerts its biological activities through two molecules: IL-6R (IL-6 receptor) and gp130. When IL-6 binds to mIL-6R (membrane-bound form of IL-6R), homodimerization of gp130 is induced and a high-affinity functional receptor complex of IL-6, IL-6R and gp130 is formed. Interestingly, sIL-6R (soluble form of IL-6R) also binds with IL-6, and the IL-6-sIL-6R complex can then form a complex with gp130. The homodimerization of receptor complex activates JAKs (Janus kinases) that then phosphorylate tyrosine residues in the cytoplasmic domain of gp130. The gp130-mediated JAK activation by IL-6 triggers two main signalling pathways: the gp130 Tyr759-derived SHP-2 (Src homology 2 domain-containing protein tyrosine phosphatase-2)/ERK (extracellular-signal-regulated kinase) MAPK (mitogen-activated protein kinase) pathway and the gp130 YXXQ-mediated JAK/STAT (signal transducer and activator of transcription) pathway. Increased IL-6 levels are observed in several human inflammatory diseases, such as rheumatoid arthritis, Castleman's disease and systemic juvenile idiopathic arthritis. IL-6 is also critically involved in experimentally induced autoimmune diseases. All clinical findings and animal models suggest that IL-6 plays a number of critical roles in the pathogenesis of autoimmune diseases. In the present review, we first summarize the IL-6/IL-6R system and IL-6 signal transduction, and then go on to discuss the physiological and pathological roles of IL-6.

IL-6 plays an essential role in neutrophilia under inflammation.

In the present study, we explored the involvement of interleukin-6 (IL-6) in neutrophilia under inflammatory conditions. The neutrophil count in the peripheral blood was high in arthritic monkeys, and anti-IL-6 receptor antibody reduced neutrophil counts to normal levels. IL-6 injection into normal monkeys significantly increased neutrophil counts in the blood 3h after injection. The expression of cluster of differentiation (CD) 162 on circulating neutrophils was reduced by IL-6 injection. IL-6 treatment in vitro did not affect CD162 expression on neutrophils from human blood. In IL-6-treated monkeys, IL-8 and granulocyte-macrophage colony-stimulating factor (GM-CSF) levels in plasma were clearly elevated. IL-8 and GM-CSF treatment in vitro reduced cell-surface CD162 expression on human neutrophils, and moreover, increased soluble CD162 expression in the cell supernatant. The addition of IL-6 into human whole peripheral blood induced IL-8 production and reduced CD162 expression on neutrophils. Furthermore, IL-8 and GM-CSF augmented mRNA expression of a disintegrin and metalloprotease like domain 10 (ADAM10) in neutrophils. Knock-down of ADAM10 by siRNA in neutrophil-like HL-60 cells partially reversed the expression of CD162 reduced by GM-CSF and IL-8 on HL-60 cells. In conclusion, IL-6 induced neutrophilia and reduced CD162 expression on neutrophils in inflammation.

IL-6 blockade preferentially inhibits Th17 differentiation in collagen-induced arthritis.

We examined the time course of cytokine production by CD4 T cells from mice with collagen-induced arthritis (CIA), and we determined the influence of interleukin-6 (IL-6) blockade on cytokine production. CD4 T cells purified from spleen were cultured with both collagen and anti-CD28 antibody for 48 h and the production of interferon-γ (IFN-γ), IL-4, and IL-17 by the cells, secreted into the supernatants, was measured at various time intervals. The production of all these cytokines started 7 days after the first immunization. A marked increase in IFN-γ production was observed after the second immunization, but IL-4 and IL-17 production was not affected by a second immunization. A single injection of anti-mouse IL-6 receptor antibody (MR16-1) on the day of the first immunization suppressed the onset of arthritis. IL-17 production by CD4 T cells from MR16-1-treated mice was significantly lower than that from the control mice. On the other hand, treatment with MR16-1 showed only a tendency to suppress the production of IL-4 and IFN-γ. Injection of MR16-1 on day 21 did not suppress the onset of arthritis. We examined the direct influence of MR16-1 on cytokine production by differentiated CD4 T cells from arthritic mice. Production of IL-4, IFN-γ, and IL-17 was not affected by MR16-1. In conclusion, IL-6 inhibition preferentially suppresses the induction of Th17 cells and does not seem to impact on cytokine production of already differentiated Th17 cells.

Induction of high-dose tolerance to the rat anti-mouse IL-6 receptor antibody in NZB/NZW F1 mice.

MR16-1 is a monoclonal antibody to mouse IL-6 receptor (IL-6R) and a good tool to investigate the involvement of IL-6 in mouse disease models. However, long-term administration of MR16-1 induced anti-MR16-1 antibody that inhibited IL-6 blocking activity of MR16-1. In this study, we treated NZB/NZW F1 (BWF1) mice with MR16-1 (0.5 mg, weekly) and tested for proteinuria (an indicator of autoimmune disease) after inducing tolerance by intraperitoneal injection of anti-CD4 mAb, or in an exploratory experiment, by prior intravenous injection of 2 mg MR16-1. Anti-CD4 mAb treatment inhibited anti-MR16-1 antibody production. And the appearance of proteinuria was significantly delayed. However, anti-CD4 mAb injection alone also significantly delayed the onset of nephritis compared with saline treatment. Intravenous MR16-1 (2 mg) followed by weekly MR16-1 injections inhibited the production of anti-MR16-1 antibody and consequently decreased the prevalence of proteinuria and the level of anti-DNA antibodies. These results established the viability of intravenous MR16-1 injection as a means of inducing tolerance. It is superior to the anti-CD4 mAb method because it enabled the effects of MR16-1 monotherapy to be evaluated without the confounding effects of anti-CD4 mAb.

Characterization of ribavirin uptake systems in human hepatocytes.

BACKGROUND & AIMS: The purpose of this study was to identify the major ribavirin uptake transporter(s) in human hepatocytes and to determine if these previously unidentified transporters are involved in hepatic ribavirin uptake. Furthermore, we aimed to address what causes the difference in uptake levels among human hepatocytes. METHODS: Profiles of ribavirin uptake and nucleoside transporter mRNA expression in Caucasian hepatocytes (HH268, HH283 and HH291) were characterized by transport assay and reverse transcription-polymerase chain reaction (RT-PCR). The 5'-side of the SLC29A1 gene structure was characterized by determination of transcription start sites and by RT-PCR. RESULTS: Equilibrative nucleoside transporter 1 (ENT1)-mediated uptake was exclusively involved in ribavirin uptake in HH268 and HH283 and was responsible for the largest ribavirin uptake fraction in HH291. The level of ENT1-mediated uptake in HH291 was higher than that in HH268 and HH283. Characterization of the SLC29A1 gene structure revealed the existence of several ENT1 mRNA isoforms in the human liver, and the levels of four ENT1 mRNA isoforms in HH291 were higher than those in HH268 or HH283. No ENT2-mediated uptake was observed in any hepatocyte lines. Na(+)-dependent uptake was detected only in HH291; however, mRNA levels of concentrative nucleoside transporters (CNTs) were at trace levels in all hepatocyte lines. CONCLUSIONS: ENT1, but not ENT2 or CNTs, is a major ribavirin uptake transporter in human hepatocytes. The different ENT1-mediated ribavirin uptake levels in different hepatocyte lines are associated with different expression levels of specific isoforms of ENT1 mRNAs. Furthermore, an unidentified Na(+)-dependent ribavirin transport system might exist in human hepatocytes.

Striking species difference in the contribution of concentrative nucleoside transporter 2 to nucleoside uptake between mouse and rat hepatocytes.

Concentrative nucleoside transporter 2 (CNT2) (encoded by the SLC28A2 gene) transports various antiviral or antitumor purine nucleoside analogs to be involved in their pharmacokinetics and pharmacological actions. The results of our study showed that mouse hepatocytes hardly expressed CNT2 mRNA and no CNT2-dependent nucleoside uptake was observed, while rat hepatocytes exhibited high CNT2-dependent nucleoside uptake activity levels with abundant CNT2 mRNA expression. We concluded that CNT2 contributes considerably to nucleoside uptake in rat hepatocytes but not in mouse hepatocytes.

High molecular weight hyaluronic acid inhibits IL-6-induced MMP production from human chondrocytes by up-regulating the ERK inhibitor, MKP-1.

To investigate the mechanism of the inhibitory action of high molecular weight hyaluronic acid (HA) on production of matrix metalloproteinases (MMPs) induced by IL-6 in human chondrocyte. Human chondrocyte were stimulated by interleukin-6 (IL-6) and soluble IL-6 receptor (sIL-6R) with or without HA for 24h and the productions of MMP-1, MMP-3 and MMP-13 were measured. Phosphorylations of extracellular signal-regulated kinase (ERK), signal transducer and activator of transcription (STAT) and mitogen-activated protein kinase kinase (MEK) in IL-6+sIL-6R-treated chondrocytes were detected by western blotting. IL-6+sIL-6R induced MMP-1, MMP-3 and MMP-13 productions from human chondrocyte. Inhibition of the mitogen-activated protein kinase (MAPK) signaling pathway resulted in marked decreases of MMP-1, MMP-3 and MMP-13 induction by IL-6. In contrast, STAT inhibition only slightly attenuated the production of MMPs. HA inhibited MMP-1, MMP-3 and MMP-13 induction by IL-6, which was reversed by the addition of anti-CD44 antibody but not anti-ICAM-1 antibody. Pre-treatment of cells with HA reduced the phosphorylation of ERK, but not MEK. Expression levels of mitogen-activated protein kinase phosphatase-1 (MKP-1) in HA-treated chondrocytes were assessed by western blotting. HA induced the expression of MKP-1, a negative regulator of ERK1/2 in IL-6+sIL-6R-treated or untreated chondrocytes, and the MKP-1 inhibitor and MKP-1 siRNA reversed the HA-induced suppression of MMP induction by IL-6. Our study is the first to demonstrate that HA suppressed MMPs induction by IL-6 in human chondrocyte via MKP-1 induction through CD44 signaling.

Overproduced interleukin 6 decreases blood lipid levels via upregulation of very-low-density lipoprotein receptor.

BACKGROUND: Interleukin 6 (IL6) blockade raises blood lipid levels in patients with rheumatoid arthritis. OBJECTIVE: To examine the influence of IL6 on lipid metabolism. METHODS: Vascular smooth muscle cells (VSMC) were cultured in the presence of IL6, soluble IL6 receptor (sIL6R), IL6+sIL6R or tumour necrosis factor alpha (TNFalpha) for 24 h. After culture, the expression of very-low-density lipoprotein receptor (VLDLR), low-density lipoprotein receptor (LDLR) and low-density lipoprotein-related protein-1 (LRP-1) were measured by real-time PCR. Human IL6 was injected into mice twice a day for 2 weeks and then VLDLR expression in several tissues and the change of total cholesterol (TC) and triglyceride (TG) levels were investigated. Finally, the effect of anti-IL6 receptor (IL6R) antibody injection on blood lipid levels was examined. RESULTS: IL6+sIL6R significantly induced expression of VLDLR mRNA in VSMC (8.6-fold, p<0.05), but IL6 or sIL6R alone and TNFalpha did not do so. None of these cytokines induced LDLR and LRP-1 mRNA expression. IL6 injection into mice increased the expression of VLDLR in heart, adipose tissue and liver and decreased TC and TG levels. The injection of anti-IL6R antibody normalised the reduced levels of TC and TG caused by IL6 injection, whereas it had no influence on the levels of TC and TG in normal mice. CONCLUSIONS: Overproduced IL6 decreased blood lipid levels by increasing VLDLR expression in several tissues. It is concluded that IL6 blockade normalises reduced lipid levels caused by IL6, but does not affect normal lipid metabolism.

IL-6 and IL-1 synergistically enhanced the production of MMPs from synovial cells by up-regulating IL-6 production and IL-1 receptor I expression.

In the present study, we investigated potential synergism between IL-6 and IL-1 for the production of matrix metalloproteinases (MMPs) by the synovial cell line SW982. Cells were cultured with different combinations of IL-6, soluble IL-6 receptor (sIL-6R) and IL-1beta for 24h and production of MMPs was then measured. IL-6+sIL-6R, but not IL-6 alone, induced MMP-13 and MMP-3 production. IL-1beta also induced production of MMPs. Of interest, addition of IL-6+sIL-6R together with IL-1beta synergistically increased MMP production. Next, we analyzed the mechanism responsible for the synergistic effects of IL-6+sIL-6R and IL-1beta in combination. IL-1beta-induced MMP production was significantly augmented in the presence of sIL-6R. IL-1beta as well as IL-6+sIL-6R induced IL-6 production. Moreover, IL-6+sIL-6R significantly augmented expression of IL-1RI, but not IL-1RII, in SW982 cells. Responsiveness to IL-1beta was much higher in IL-6+sIL-6R-pretreated cells than non-treated cells in terms of MMP production. Finally, IL-6+sIL-6R-induced IL-1RI expression was inhibited by a STAT pathway inhibitor, but not a MAPK pathway inhibitor. These results suggest that increased expression of IL-1RI stimulated by IL-6+sIL-6R and the increased production of IL-6 on exposure to IL-1beta and IL-6+sIL-6R are involved in the observed synergistic effect on the production of MMPs by SW982 cells.

Anti-inflammatory mechanism of tocilizumab, a humanized anti-IL-6R antibody: effect on the expression of chemokine and adhesion molecule.

We studied the influence of IL-6 on chemokine production from peripheral blood mononuclear cells (PBMC), fibroblastic synovial cells and human umbilical vessel endothelial cells (HUVEC). Moreover, we examined the effect of IL-6 on the adhesion of U937 cells to HUVEC. For chemokine production, PBMC, fibroblastic synovial cells and HUVEC were cultured with IL-6 or IL-6 + soluble IL-6R (sIL-6R) for 24 h and then the production of MCP-1 and IL-8 were measured in supernatants. IL-6 and IL-6 + sIL-6R induced production of both MCP-1 and IL-8 in PBMC and synovial cells, respectively. In HUVEC, IL-6 + sIL-6R induced MCP-1 production, but inhibited IL-8 production. For adhesion molecule expression, the production of soluble form of adhesion molecules in HUVEC culture supernatant were measured by ELISA and the expression of adhesion molecules on cell surface were examined by flow cytometry analysis. Soluble ICAM-1 was detectable in IL-6 + sIL-6R-treated HUVEC and IL-6 + sIL-6R-induced ICAM-1 expression on cell membrane of HUVEC. In addition, U937 cells were added to HUVEC, which were pre-treated with IL-6 + sIL-6R for 24 h, and 3 h later attached U937 cells were counted. The adhesion of U937 cells to HUVEC was augmented when HUVEC was pretreated by IL-6 + sIL-6R. This adhesion was suppressed by anti-ICAM-1 antibody and anti-IL-6R antibody, but not by antibodies against VCAM-1 or E-selectin. In conclusion, IL-6 signaling plays an important role in inflammatory cell migration by increasing the rate of cell adhesion and by inducing chemokine production in inflamed joints.

Tocilizumab, a humanized anti-interleukin-6 receptor antibody, improved anemia in monkey arthritis by suppressing IL-6-induced hepcidin production.

We have reported that serum IL-6 level was related with the degree of anemia in monkey collagen-induced arthritis (CIA). In this study, we examined whether IL-6 blockade ameliorated an anemia in monkey CIA. CIA was induced by twice immunization of bovine type II collagen with adjuvant. When anemia became evident, anti-IL-6 receptor antibody, tocilizumab was intravenously injected once a week for 4 weeks. Controls received PBS in a same manner. Hematological and biochemical parameters were measured regularly and serum hepcidin-25 levels were measured by SELDI-TOF mass spectrometry. Moreover, hepcidin mRNA induction in Hep3B cells by serum from arthritic monkeys was examined by real-time PCR. Administration of tocilizumab rapidly decreased CRP levels and improved iron-deficient anemia within 1 week. Tocilizumab induced rapid but transient reduction in serum hepcidin-25. Hepcidin mRNA expression was more potently induced by serum from arthritic monkey and this was inhibited by the addition of tocilizumab. Blockade of IL-6 signaling rapidly improved anemia in monkey arthritis via the inhibition of IL-6-induced hepcidin production.

High molecular weight hyaluronic acid relieved joint pain and prevented the progression of cartilage degeneration in a rabbit osteoarthritis model after onset of arthritis.

We examined the therapeutic effect of high molecular weight hyaluronic acid (HA) on the progression of joint pain and cartilage degeneration in a rabbit osteoarthritis (OA) model. The OA model was induced by partial meniscectomy. In the time course study, cartilage degeneration was assessed at 3, 7 and 14 days after operation. In the therapeutic study, HA or loxoprofen (LOX) was administered for 14 days beginning four days after operation (after the onset of knee pain and cartilage degeneration). Knee pain was assessed by weight distribution on the hind paw, and cartilage damage and MMP production in the joints were evaluated 18 days after surgery. In the time course study, severe cartilage damage was found three days after operation. In the treatment study, weight-bearing on the injured paw in the control group decreased with time from four days after the operation. However, HA or LOX treatment beginning four days after the operation normalized the reduced hind paw weight distribution, and PGE(2) production was inhibited by HA treatment and LOX treatment. HA significantly inhibited cartilage degeneration, whereas LOX did not. HA also suppressed the production of MMP in joints. Treatment of HA after the onset of cartilage destruction and pain showed a cartilage protective effect as well as an analgesic effect.

Outlook of IL-6 signaling blockade for COVID-19 pneumonia.

In this review article, it is highlighted the implications of pleiotropic functions of interleukin-6 (IL-6) for one of the therapeutic options targeting for COVID-19. Moreover, it is discussed how real-world data and trials with IL-6 signaling blockade will be crucial in informing the development of new treatment for COVID-19 pneumonia. Given physiological roles of IL-6 in inflammatory conditions and the data from real world, IL-6 signal inhibitors, along with standard of care (SOC) treatment, might provide efficacy, offering the potential to treat COVID-19 in hospitalized populations more effectively than current SOC alone. Therefore, on-going and planned randomized placebo-controlled studies in combination with SOC and other therapeutics to assess safety and efficacy of IL-6 signal inhibitors in hospitalized patients with severe COVID-19 pneumonia will be warranted to address the high unmet need and burden of disease in this severely ill population.

Translating IL-6 biology into effective treatments.

In 1973, IL-6 was identified as a soluble factor that is secreted by T cells and is important for antibody production by B cells. Since its discovery more than 40 years ago, the IL-6 pathway has emerged as a pivotal pathway involved in immune regulation in health and dysregulation in many diseases. Targeting of the IL-6 pathway has led to innovative therapeutic approaches for various rheumatic diseases, such as rheumatoid arthritis, juvenile idiopathic arthritis, adult-onset Still's disease, giant cell arteritis and Takayasu arteritis, as well as other conditions such as Castleman disease and cytokine release syndrome. Targeting this pathway has also identified avenues for potential expansion into several other indications, such as uveitis, neuromyelitis optica and, most recently, COVID-19 pneumonia. To mark the tenth anniversary of anti-IL-6 receptor therapy worldwide, we discuss the history of research into IL-6 biology and the development of therapies that target IL-6 signalling, including the successes and challenges and with an emphasis on rheumatic diseases.

Influence of humanized anti-IL-6R antibody, tocilizumab on the activity of soluble gp130, natural inhibitor of IL-6 signaling.

Tocilizumab, humanized anti-IL-6R antibody is a novel anti-rheumatic drug. In the present study, we examined the influence of tocilizumab on the inhibitory activity of soluble gp130 (sgp130) against IL-6 signaling. BAF-h130 cells, human gp130 transfected mouse pro-B cell line, were cultured with the mixture with IL-6, sIL-6R and sgp130 for 72 h. BAF-h130 cells proliferated by the addition of both IL-6 and sIL-6R, but not IL-6 or sIL-6R alone. The proliferation induced by IL-6/sIL-6R complex was inhibited by sgp130 concentration-dependently. Tocilizumab inhibited IL-6/sIL-6R-induced cell proliferation. On the other hand, it did not affect the suppressive property of sgp130. To examine if tocilizumab can dissociate IL-6/sIL-6R/sgp130 complex, we established an ELISA system to detect IL-6/sIL-6R/sgp130 complex using anti-IL-6R coated ELISA plate. The results clearly indicated that ELISA system established was detectable IL-6/sIL-6R/sgp130 complex in a concentration dependent manner. Tocilizumab was added to IL-6/sIL-6R/sgp130 complex-fixed plate and then remaining IL-6/sIL-6R/sgp130 complexes on the plate were measured. The amount of IL-6/sIL-6R/sgp130 complexes on the plate was not changed by the addition of tocilizumab. In conclusion, tocilizumab exerts its inhibitory effect through the inhibition of IL-6R directly without affecting natural inhibitor sgp130.