Efficacy and safety of bimekizumab in axial spondyloarthritis: results of two parallel phase 3 randomised controlled trials

OBJECTIVES

Axial spondyloarthritis (axSpA) is a complex disease with diverse manifestations, for which new treatment options are warranted. BE MOBILE 1 (non-radiographic (nr)-axSpA) and BE MOBILE 2 (radiographic axSpA (r-axSpA)) are double-blind, phase 3 trials designed to evaluate efficacy and safety of bimekizumab, a novel dual interleukin (IL)-17A and IL-17F inhibitor, across the axSpA spectrum.

METHODS

In parallel 52-week trials, patients with active disease were randomised 1:1 (nr-axSpA) or 2:1 (r-axSpA) to bimekizumab 160 mg every 4 weeks:placebo. From week 16, all patients received bimekizumab 160 mg every 4 weeks. Primary (Assessment of SpondyloArthritis international Society ≥40% improvement (ASAS40)) and secondary endpoints were assessed at week 16. Here, efficacy and treatment-emergent adverse events (TEAEs) are reported up to week 24.

RESULTS

254 patients with nr-axSpA and 332 with r-axSpA were randomised. At week 16, primary (ASAS40, nr-axSpA: 47.7% bimekizumab vs 21.4% placebo; r-axSpA: 44.8% vs 22.5%; p<0.001) and all ranked secondary endpoints were met in both trials. ASAS40 responses were similar across TNFi-naïve and TNFi-inadequate responder patients. Improvements were observed in Ankylosing Spondylitis Disease Activity Score (ASDAS) states and objective measures of inflammation, including high-sensitivity C-reactive protein (hs-CRP) and MRI of the sacroiliac joints and spine. Most frequent TEAEs with bimekizumab (>3%) included nasopharyngitis, upper respiratory tract infection, pharyngitis, diarrhoea, headache and oral candidiasis. More fungal infections (all localised) were observed with bimekizumab vs placebo; no major adverse cardiovascular events (MACE) or active tuberculosis were reported. Incidence of uveitis and adjudicated inflammatory bowel disease was low.

CONCLUSIONS

Dual inhibition of IL-17A and IL-17F with bimekizumab resulted in significant and rapid improvements in efficacy outcomes vs placebo and was well tolerated in patients with nr-axSpA and r-axSpA.

Minimal Impact of the COVID ‐19 Pandemic on Disease Activity and Health‐Related Quality of Life in Patients With Ankylosing Spondylitis Receiving Bimekizumab: Exploratory Analyses From a Phase 2b Open‐Label Extension Study

Objective

The impact of the COVID‐19 pandemic on patients with inflammatory rheumatic diseases, such as ankylosing spondylitis (AS), has been variable. Here, we assess disease activity and health‐related quality of life (HRQoL) through the pandemic in patients with AS.

Methods

In the open‐label extension (OLE) of the phase 2b BE AGILE study, patients with AS received 160 mg of subcutaneous bimekizumab every 4 weeks. We assessed Ankylosing Spondylitis Disease Activity Score with C‐reactive protein (ASDAS‐CRP), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Ankylosing Spondylitis Quality of Life (ASQoL) scores in the OLE immediately before and during the COVID‐19 pandemic (September 2019 to April 2021).

Results

A total of 232 patients remained in the BE AGILE OLE and were included in this post hoc study at the start of the analysis period (September 1, 2019); 12 patients had a COVID‐19 treatment‐emergent adverse event, and no cases resulted in death. The number of missed bimekizumab doses due to COVID‐19 (11 doses) was minimal, and missed assessments remained low (≤5%) compared with the prepandemic period. Mean ASDAS‐CRP (1.8), BASDAI (2.4), and ASQoL scores (2.8) in the OLE were low at pre‐pandemic baseline and remained stable at 1.7 to 1.8, 2.2 to 2.4, and 2.0 to 2.8, respectively, across successive 3‐month periods immediately before and during the pandemic. ASDAS‐CRP, BASDAI, and ASQoL stability was consistent across major study countries.

Conclusion

Disease activity and HRQoL remained stable during the COVID‐19 pandemic in patients with AS receiving bimekizumab in the BE AGILE OLE, with no indication of negative effects on these outcomes.

POS0938 MAINTENANCE OF RESPONSE TO BIMEKIZUMAB OVER 3 YEARS OF TREATMENT IN PATIENTS WITH ACTIVE ANKYLOSING SPONDYLITIS: POST HOC ANALYSES FROM THE BE AGILE STUDY AND ITS OPEN-LABEL EXTENSION

Background

Bimekizumab (BKZ), a monoclonal IgG1 antibody that selectively inhibits interleukin (IL)-17F in addition to IL 17A, has demonstrated significant and rapid efficacy in patients (pts) with active ankylosing spondylitis (AS) treated for up to 48 weeks (wks) in the phase 2b BE AGILE study.1 Maintaining stringent disease control is an internationally recognised treatment target in spondyloarthritis and a relevant goal in clinical research.2

Objectives

To report on the maintenance of clinical response, including the achievement of sustained remission or low disease activity (LDA), to support and extend previous findings on the long-term efficacy of BKZ in pts with active AS treated for up to 3 years (yrs) in BE AGILE and its open-label extension (OLE).3

Methods

Study design of the 48-wk BE AGILE study (NCT02963506) and its ongoing 4-yr OLE (NCT03355573) have been reported previously.1,3 During the OLE, pts received BKZ 160 mg every 4 wks (Q4W) regardless of prior dosing. In this post hoc study, maintenance of response analyses through 156 wks were conducted for Ankylosing Spondylitis Disease Activity Score (ASDAS) <2.1 and Assessment in SpondyloArthritis international Society 40 (ASAS40) response. ASDAS <2.1 includes both ASDAS-LDA (1.3–<2.1) and ASDAS inactive disease (ID; <1.3). Data from pts randomised at baseline to BKZ 160 mg and 320 mg Q4W were used for these analyses. ASDAS and the ASAS components were assessed at every study visit to Wk 24, then every 12 wks. All reported analyses are observed case.

Results

At baseline, 121/303 pts were randomised to BKZ 160 mg (n=60) or 320 mg (n=61). Overall, 36/121 (29.8%) had ASDAS high disease (HD) and 84/121 (69.4%) had very high disease (VHD) activity. At Wk 12, 48/119 (40.3%) had achieved ASDAS <2.1, increasing further to 66/111 (59.5%) at Wk 48 and 63/93 (67.7%) at Wk 156, of which 32 pts (32/63; 50.8%) had ID. Improvement in ASDAS was consistent across both BKZ 160 mg and 320 mg groups, with treatment response levels maintained following dose reduction to 160 mg at Wk 48 in the 320 mg group (Figure 1).

Of those pts who achieved ASDAS <2.1 at Wk 12 across both groups, 33/37 (89.2%) maintained ASDAS <2.1 at Wk 156. In the most stringent maintenance of response analysis, 24/37 (64.9%) pts who achieved ASDAS <2.1 at Wk 12 maintained this state at every ASDAS assessment during Wks 12–156. Efficacy measured by ASAS40 response was also sustained over 3 years, with 56/119 (47.1%) pts having achieved ASAS40 at Wk 12, 72/111 (64.9%) at Wk 48 and 69/96 (71.9%) at Wk 156. In line with ASDAS <2.1, of those pts who achieved ASAS40 at Wk 12, 44/47 (93.6%) maintained ASAS40 at Wk 156, and 36/47 (76.6%) had maintained ASAS40 at every assessment during Wks 12–156.

Conclusion

BKZ 160 mg Q4W provided a robust maintenance of disease control over 3 yrs in pts with active AS who initially responded at Wk 12, irrespective of the initial dosing regimen (BKZ 160 mg or 320 mg Q4W).

References

[1]van der Heijde D. Ann Rheum Dis 2020;79:595–604; 2. Smolen J. Ann Rheum Dis 2018;77:3–17; 3. Gensler L. Arthritis Rheumatol 2021;73(suppl 10):0491.

Acknowledgements

This study was funded by UCB Pharma. Editorial services were provided by Costello Medical.

Disclosure of Interests

Victoria Navarro-Compán Speakers bureau: AbbVie, Eli Lilly, Janssen, MSD, Novartis, Pfizer, UCB Pharma, Consultant of: AbbVie, Eli Lilly, MSD, Novartis, Pfizer, UCB Pharma, Grant/research support from: AbbVie and Novartis, Martin Rudwaleit Speakers bureau: AbbVie, BMS, Boehringer Ingelheim, Chugai, Eli Lilly, Janssen, Novartis, Pfizer, UCB Pharma, Paid instructor for: Janssen, Novartis, UCB Pharma, Consultant of: AbbVie, Novartis, UCB Pharma, Natasha de Peyrecave Employee of: UCB Pharma, Carmen Fleurinck Employee of: UCB Pharma, Marga Oortgiesen Employee of: UCB Pharma, Vanessa Taieb Employee of: UCB Pharma, Xenofon Baraliakos Speakers bureau: AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, MSD, Novartis, Pfizer, UCB Pharma, Paid instructor for: AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, MSD, Novartis, Pfizer, UCB Pharma, Consultant of: AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, MSD, Novartis, Pfizer, UCB Pharma

POS0939 BIMEKIZUMAB IN PATIENTS WITH ACTIVE NON-RADIOGRAPHIC AXIAL SPONDYLOARTHRITIS: 24-WEEK EFFICACY & SAFETY FROM BE MOBILE 1, A PHASE 3, MULTICENTRE, RANDOMISED, PLACEBO‑CONTROLLED STUDY

Background

Bimekizumab (BKZ) is a monoclonal IgG1 antibody that selectively inhibits IL-17F in addition to IL-17A. BKZ has shown rapid and sustained efficacy and was well tolerated up to 156 weeks (wks) in a phase 2b study in patients (pts) with active ankylosing spondylitis.1,2

Objectives

To assess efficacy and safety of BKZ vs placebo (PBO) in pts with active non-radiographic axial spondyloarthritis (nr-axSpA) up to Wk 24 in the ongoing pivotal phase 3 study, BE MOBILE 1.

Methods

BE MOBILE 1 (NCT03928704) comprises a 16-wk double-blind, PBO-controlled period and 36-wk maintenance period. Pts were aged ≥18 yrs, had BASDAI ≥4 and spinal pain ≥4 at BL, and sacroiliitis on MRI and/or elevated CRP at screening. Pts were randomised 1:1, BKZ 160 mg Q4W:PBO. From Wk 16, all pts received BKZ 160 mg Q4W. Primary and secondary efficacy endpoints were assessed at Wk 16.

Results

Of 254 randomised pts (BKZ: 128; PBO: 126), 244 (96.1%) completed Wk 16, 240 (94.5%) Wk 24. BL characteristics were comparable between groups: mean age 39.4 yrs, symptom duration 9.0 yrs; 54.3% pts male, 77.6% HLA-B27+, 10.6% TNFi-experienced. At Wk 16, the primary (ASAS40: 47.7% BKZ vs 21.4% PBO; p<0.001) and all ranked secondary endpoints were met (Table 1). Responses were rapid with BKZ, including in PBO pts who switched to BKZ at Wk 16, and increased to Wk 24 (Figure 1; Table 1). Substantial reductions of hs-CRP by Wk 2 and MRI SIJ inflammation by Wk 16 were achieved with BKZ vs PBO (Table 1). At Wk 24, >50% of pts initially randomised to BKZ had achieved ASDAS <2.1 (Figure 1).

Table 1.

Efficacy at Wks 16 and 24

BLWk 16Wk 24PBO N=126BKZ 160 mg Q4W N=128PBO N=126BKZ 160 mg Q4W N=128p valuePBO→BKZ 160 mg Q4W N=126BKZ 160 mg Q4W N=128Ranked endpoints in hierarchical orderASAS40* [NRI] n (%)--27 (21.4)61 (47.7)<0.00159 (46.8)67 (52.3)BASDAI CfB† [MI] mean (SE)6.7 (0.1)6.9 (0.1)–1.5 (0.2)–3.1 (0.2)<0.001–3.2 (0.2)–3.4 (0.2)ASAS20† [NRI] n (%)--48 (38.1)88 (68.8)<0.00187 (69.0)96 (75.0)ASAS PR† [NRI] n (%)--9 (7.1)33 (25.8)<0.00135 (27.8)37 (28.9)ASDAS-MI† [NRI] n (%)--9 (7.1)35 (27.3)<0.00137 (29.4)41 (32.0)ASAS 5/6† [NRI] n (%)--21 (16.7)49 (38.3)<0.00151 (40.5)57 (44.5)BASFI CfB† [MI] mean (SE)5.3 (0.2)5.5 (0.2)–1.0 (0.2)–2.5 (0.2)<0.001–2.3 (0.2)–2.8 (0.2)Nocturnal spinal pain CfB† [MI] mean (SE)6.7 (0.2)6.9 (0.2)–1.7 (0.2)–3.6 (0.3)<0.001–3.5 (0.2)–4.0 (0.3)ASQoL CfB† [MI] mean (SE)9.4 (0.4)9.5 (0.4)–2.5 (0.4)–5.2 (0.4)<0.001–4.8 (0.4)–5.7 (0.4)SF-36 PCS CfB† [MI] mean (SE)33.6 (0.8)33.3 (0.7)5.5 (0.7)9.5 (0.7)<0.00110.1 (0.8)10.6 (0.8)Other endpointsdEnthesitis-free state†a [NRI] n (%)--22 (23.9)b48 (51.1)c-40 (43.5)b45 (47.9)cASAS40 in TNFi-experienced [NRI] n (%)--2 (11.8)e6 (60.0)f---ASDAS-CRP CfB [MI] mean (SE)3.7 (0.1)3.8 (0.1)–0.6 (0.1)–1.5 (0.1)-–1.5 (0.1)–1.6 (0.1)hs-CRP, mg/L [MI] geometric mean (median)5.0 (6.5)4.6 (6.1)3.8 (4.1)2.0 (1.8)-2.3 (2.6)1.9 (1.8)MRI spine Berlin CfBg [OC] mean (SD)1.9 (3.2)h1.6 (2.9)i–0.1 (1.7)j–0.7 (2.2)k---SPARCC MRI SIJ score CfBg [OC] mean (SD)10.5 (13.8)l8.5 (10.3)m–1.5 (9.2)n–6.3 (10.0)o---

Randomised set. *Primary endpoint; †Secondary endpoint; aMASES=0 in pts with BL MASES >0; bn=92; cn=94; dNominal p values not shown; en=17; fn=10; gIn pts in MRI sub-study; hn=65; in=75; jn=58; kn=73; ln=68; mn=79; nn=60; on=77.

Over 16 wks, 80/128 (62.5%) pts had ≥1 TEAE on BKZ vs 71/126 (56.3%) on PBO; most frequent were nasopharyngitis (BKZ: 9.4%; PBO: 4.8%), upper respiratory tract infection (BKZ: 7.0%; PBO: 7.1%) and oral candidiasis (BKZ: 3.1%; PBO: 0%). No systemic candidiasis was observed. Up to 16 wks, incidence of SAEs was low (BKZ: 0.0%; PBO: 0.8%); no MACE or deaths were reported; 0 IBD cases occurred in pts on BKZ vs 1 (0.8%) in a pt on PBO.

Conclusion

Dual inhibition of IL-17A and IL-17F with BKZ in pts with active nr-axSpA resulted in rapid, clinically relevant improvements in efficacy outcomes vs PBO. No new safety signals were observed.1,2

References

[1]van der Heijde D. Ann Rheum Dis 2020;79:595–604;

[2]Gensler L. Arthritis Rheumatol 2021;73(suppl 10):0491.

Acknowledgements

This study was funded by UCB Pharma. Editorial services were provided by Costello Medical.

Disclosure of Interests

Atul Deodhar Speakers bureau: Janssen, Novartis, and Pfizer, Consultant of: AbbVie, Amgen, Aurinia, BMS, Celgene, Eli Lilly, GSK, Janssen, MoonLake, Novartis, Pfizer, and UCB Pharma, Grant/research support from: AbbVie, Eli Lilly, GSK, Novartis, Pfizer, and UCB Pharma, Désirée van der Heijde Consultant of: AbbVie, Bayer, BMS, Cyxone, Eisai, Galapagos, Gilead, Glaxo-Smith-Kline, Janssen, Lilly, Novartis, Pfizer, and UCB Pharma, Employee of: Imaging Rheumatology BV (Director), Lianne S. Gensler Consultant of: AbbVie, Eli Lilly, GSK, Janssen, Novartis, Pfizer, and UCB Pharma, Grant/research support from: Novartis, Pfizer and UCB Pharma, Huji Xu: None declared, Karl Gaffney Speakers bureau: AbbVie, Eli Lilly, Novartis, UCB Pharma, Consultant of: AbbVie, Eli Lilly, Novartis, and UCB Pharma, Grant/research support from: AbbVie, Gilead, Eli Lilly, Novartis, and UCB Pharma, Hiroaki Dobashi Speakers bureau: BMS, Chugai, Eli Lilly, GSK, MSD, Novartis, Pfizer, UCB Pharma, Walter P Maksymowych Consultant of: AbbVie, Boehringer-Ingelheim, Celgene, Eli Lilly, Galapagos, Janssen, Novartis, Pfizer and UCB Pharma, Grant/research support from: AbbVie, Janssen, Novartis and Pfizer, Employee of: Chief Medical Officer for CARE Arthritis, Martin Rudwaleit Speakers bureau: AbbVie, BMS, Boehringer Ingelheim, Chugai, Eli Lilly, Janssen, Novartis, Pfizer, and UCB Pharma, Paid instructor for: Janssen, Novartis, and UCB Pharma, Consultant of: AbbVie, Novartis, and UCB Pharma, Marina Magrey Consultant of: AbbVie, Eli Lilly, Novartis, Pfizer and UCB Pharma, Grant/research support from: AbbVie and UCB Pharma, Dirk Elewaut Speakers bureau: AbbVie, Eli Lilly, Galapagos, Novartis and UCB Pharma, Consultant of: AbbVie, Eli Lilly, Galapagos, Novartis and UCB Pharma, Marga Oortgiesen Employee of: Employee of UCB Pharma, Carmen Fleurinck Employee of: Employee of UCB Pharma, Alicia Ellis Employee of: Employee of UCB Pharma, Thomas Vaux Employee of: Employee of UCB Pharma, julie smith Employee of: Employee of UCB Pharma, Xenofon Baraliakos Speakers bureau: AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, MSD, Novartis, Pfizer, and UCB Pharma, Paid instructor for: AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, MSD, Novartis, Pfizer, and UCB Pharma, Consultant of: AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, MSD, Novartis, Pfizer, and UCB Pharma

OP0019 BIMEKIZUMAB IN PATIENTS WITH ACTIVE ANKYLOSING SPONDYLITIS: 24-WEEK EFFICACY & SAFETY FROM BE MOBILE 2, A PHASE 3, MULTICENTRE, RANDOMISED, PLACEBO-CONTROLLED STUDY

Background

Bimekizumab (BKZ) is a monoclonal IgG1 antibody that selectively inhibits IL-17F in addition to IL-17A. In a phase 2b study, BKZ showed rapid and sustained efficacy and was well tolerated up to 156 weeks (wks) in patients (pts) with active ankylosing spondylitis (AS).1,2

Objectives

To assess efficacy and safety of BKZ vs placebo (PBO) in pts with active AS up to Wk 24 in the ongoing pivotal phase 3 study, BE MOBILE 2.

Methods

BE MOBILE 2 (NCT03928743) comprises a 16-wk double-blind, PBO-controlled period and 36-wk maintenance period. Pts were aged ≥18 yrs, met modified New York criteria and had active AS (BASDAI ≥4, spinal pain ≥4) at BL. Pts were randomised 2:1, BKZ 160 mg Q4W:PBO. From Wk 16, all pts received BKZ 160 mg Q4W. Primary and secondary efficacy endpoints were assessed at Wk 16.

Results

Of 332 randomised pts (BKZ: 221; PBO: 111), 322 (97.0%) completed Wk 16 and 313 (94.3%) Wk 24. BL characteristics were comparable between groups: mean age 40.4 yrs, symptom duration 13.5 yrs; 72.3% pts male, 85.5% HLA-B27+, 16.3% TNFi-experienced. At Wk 16, the primary (ASAS40: 44.8% BKZ vs 22.5% PBO; p<0.001) and all ranked secondary endpoints were met (Table 1). Responses with BKZ were rapid, including in PBO pts who switched to BKZ at Wk 16, and increased to Wk 24 (Figure 1; Table 1). Substantial reductions of hs-CRP by Wk 2 and MRI SIJ and spine inflammation by Wk 16 were achieved with BKZ vs PBO (Table 1). At Wk 24, ≥50% pts had achieved ASDAS <2.1 (Figure 1).

Table 1.

Efficacy at Wks 16 and 24

BLWk 16Wk 24PBO N=111BKZ 160 mg Q4W N=221PBO N=111BKZ 160 mg Q4W N=221p valuePBO→BKZ 160 mg Q4W N=111BKZ 160 mg Q4W N=221Ranked endpoints in hierarchical orderASAS40* [NRI] n (%)--25 (22.5)99 (44.8)<0.00163 (56.8)119 (53.8)ASAS40 in TNFi-naïve† [NRI] n (%)--22 (23.4)a84 (45.7)b<0.00156 (59.6)a100 (54.3)bASAS20† [NRI]n (%)--48 (43.2)146 (66.1)<0.00185 (76.6)159 (71.9)BASDAI CfB† [MI] mean (SE)6.5 (0.1)6.5 (0.1)–1.9 (0.2)–2.9 (0.1)<0.001–3.3 (0.2)–3.3 (0.1)ASAS PR† [NRI]n (%)--8 (7.2)53 (24.0)<0.00128 (25.2)56 (25.3)ASDAS-MI† [NRI] n (%)--6 (5.4)57 (25.8)<0.00143 (38.7)67 (30.3)ASAS 5/6† [NRI]n (%)--16 (14.4)94 (42.5)<0.00157 (51.4)107 (48.4)BASFI CfB† [MI] mean (SE)5.2 (0.2)5.3 (0.2)–1.1 (0.2)–2.2 (0.1)<0.001–2.2 (0.2)–2.4 (0.2)Nocturnal spinal pain CfB† [MI]mean (SE)6.8 (0.2)6.6 (0.1)–1.9 (0.2)–3.3 (0.2)<0.001–3.7 (0.3)–3.8 (0.2)ASQoL CfB† [MI] mean (SE)8.5 (0.4)9.0 (0.3)–3.2 (0.3)–4.9 (0.3)<0.001–4.9 (0.4)–5.4 (0.3)SF-36 PCS CfB† [MI] mean (SE)34.6 (0.8)34.4 (0.6)5.9 (0.8)9.3 (0.6)<0.00110.6 (0.8)10.8 (0.6)BASMI CfB† [MI] mean (SE)3.8 (0.2)3.9 (0.1)–0.2 (0.1)–0.5 (0.1)0.005–0.5 (0.1)–0.6 (0.1)Other endpointsnEnthesitis-free state†c [NRI]n (%)--22 (32.8)d68 (51.5)e-33 (49.3)d70 (53.0)eASAS40 in TNFi-experienced [NRI]n (%)--3 (17.6)f15 (40.5)g---ASDAS-CRP CfB [MI]mean (SE)3.7 (0.1)3.7 (0.1)–0.7 (0.1)–1.4 (0.1)-–1.7 (0.1)–1.6 (0.1)hs-CRP (mg/L) [MI] geometric mean (median)6.7 (6.3)6.5 (8.2)6.0 (6.3)2.4 (2.4)-1.9 (2.2)2.1 (2.3)MRI spine Berlin CfBh [OC] mean (SD)3.3 (4.9)i3.8 (5.3)j0.0 (1.4)k–2.3 (3.9)l---SPARCC MRI SIJ score CfBh [OC] mean (SD)5.8 (7.7)i7.4 (10.7)m1.1 (6.9)k–5.6 (9.9)l---

Randomised set. *Primary endpoint; †Secondary endpoint; an=94; bn=184; cMASES=0 in pts with BL MASES >0; dn=67; en=132; fn=17; gn=37; hIn pts in MRI sub-study; in=45; jn=82; kn=43; ln=79; mn=83; nNominal p values not shown.

Over 16 wks, 120/221 (54.3%) BKZ pts had ≥1 TEAE vs 48/111 (43.2%) PBO; three most frequent on BKZ were nasopharyngitis (BKZ: 7.7%; PBO: 3.6%), headache (4.1%; 4.5%) and oral candidiasis (4.1%; 0%). No systemic candidiasis was observed. Up to 16 wks, incidence of SAEs was low (1.8%; 0.9%); no MACE or deaths were reported; 2 (0.9%) IBD cases occurred in pts on BKZ.

Conclusion

Dual inhibition of IL-17A and IL-17F with BKZ in pts with active AS resulted in rapid, clinically relevant improvements in efficacy outcomes vs PBO. No new safety signals were observed.1,2

References

[1]van der Heijde D. Ann Rheum Dis 2020;79:595–604; 2. Gensler L. Arthritis Rheumatol 2021;73(suppl 10):0491.

Acknowledgements

This study was funded by UCB Pharma. Editorial services were provided by Costello Medical.

Disclosure of Interests

Désirée van der Heijde Consultant of: AbbVie, Bayer, BMS, Cyxone, Eisai, Galapagos, Gilead, Glaxo-Smith-Kline, Janssen, Lilly, Novartis, Pfizer, UCB Pharma, Employee of: Imaging Rheumatology BV (Director), Xenofon Baraliakos Speakers bureau: AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, MSD, Novartis, Pfizer, and UCB Pharma, Paid instructor for: AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, MSD, Novartis, Pfizer, and UCB Pharma, Consultant of: AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, MSD, Novartis, Pfizer, and UCB Pharma, Maxime Dougados Consultant of: AbbVie, Eli Lilly, Novartis, Merck, Pfizer, and UCB Pharma, Grant/research support from: AbbVie, Eli Lilly, Novartis, Pfizer, and UCB Pharma, Matt Brown Speakers bureau: Novartis, Consultant of: Pfizer, Clementia, Ipsen, Regeneron, Grey Wolf Therapeutics, Grant/research support from: UCB Pharma, Denis Poddubnyy Speakers bureau: AbbVie, BMS, Eli Lilly, MSD, Novartis, Pfizer, and UCB Pharma, Consultant of: AbbVie, Biocad, Eli Lilly, Gilead, GSK, MSD, Novartis, Pfizer, Samsung Bioepis, and UCB Pharma, Grant/research support from: AbbVie, MSD, Novartis, and Pfizer, Filip van den Bosch Speakers bureau: AbbVie, Bristol Myers-Squibb, Celgene, Janssen, Merck, Novartis, Pfizer and UCB Pharma, Consultant of: AbbVie, Amgen, Eli Lilly, Galapagos, Janssen, Merck, Novartis, Pfizer and UCB Pharma, Nigil Haroon Consultant of: AbbVie, Amgen, Janssen, Merck, Novartis and UCB Pharma, Huji Xu: None declared, Tetsuya Tomita Speakers bureau: AbbVie, Astellas, Bristol-Myers Squibb, Eisai, Eli Lilly, Janssen, Kyowa Kirin, Mitsubishi-Tanabe, Novartis, and Pfizer, Consultant of: AbbVie, Eli Lilly, Gilead, Novartis, and Pfizer, Lianne S. Gensler Consultant of: AbbVie, Eli Lilly, Gilead, GSK, Novartis, Pfizer, and UCB Pharma, Grant/research support from: Novartis, Pfizer, and UCB Pharma; paid to institution, Marga Oortgiesen Employee of: UCB Pharma, Carmen Fleurinck Employee of: UCB Pharma, Thomas Vaux Employee of: UCB Pharma, Alexander Marten Employee of: UCB Pharma, Atul Deodhar Speakers bureau: Janssen, Novartis, and Pfizer; consultant of AbbVie, Amgen, Aurinia, BMS, Celgene, Eli Lilly, GSK, Janssen, MoonLake, Novartis, Pfizer, and UCB Pharma, Grant/research support from: AbbVie, Eli Lilly, GSK, Novartis, Pfizer, and UCB Pharma.

POS0226 BIMEKIZUMAB LONG-TERM SAFETY AND EFFICACY IN PATIENTS WITH ANKYLOSING SPONDYLITIS: 3-YEAR RESULTS FROM A PHASE 2B STUDY

Background:

Bimekizumab (BKZ), a monoclonal antibody that selectively inhibits interleukin (IL)-17A and IL-17F, has demonstrated clinical efficacy and safety in patients with ankylosing spondylitis (AS) treated over a period up to 96 weeks.1,2

Objectives:

To report 3-year interim safety and efficacy of BKZ in patients with active AS from a phase 2b dose-ranging study (BE AGILE; NCT02963506) and its ongoing open-label extension (OLE; NCT03355573).

Methods:

BE AGILE study design has been described previously.1 Patients treated with BKZ 160 mg or 320 mg every 4 weeks (Q4W) at Week 48 in BE AGILE were eligible for OLE entry. All OLE patients received BKZ 160 mg Q4W. Treatment-emergent adverse events (TEAEs) are reported for the BE AGILE safety set (patients who received ≥1 dose of BKZ on study entry) for total exposure to BKZ across BE AGILE and the OLE. Efficacy outcomes are reported for the OLE full analysis set (patients who entered the OLE and had ≥1 dose of BKZ and ≥1 valid efficacy variable measurement in the OLE), and include: ASAS40, ASAS20, ASAS PR, ASDAS, ASDAS-CII, ASDAS-MI, ASDAS-ID (<1.3) and ASDAS <2.1. Data are reported as imputed (multiple imputation [MI] based on the missing at random assumption, or non-responder imputation [NRI]) and as observed case (OC).

Results:

262/303 (86%) patients randomised at BE AGILE study baseline completed Week 48 on BKZ 160 mg or 320 mg. At Week 48, 255/262 (97%) patients entered the OLE (full analysis set: 254); 219 patients had an efficacy assessment at Week 156. Over the 156 weeks, the exposure-adjusted incidence rate (EAIR) per 100 patient-years (PY) of TEAEs was 143.5, with an EAIR of 5.8 for serious TEAEs, 1.3 for serious infections, and 3.8 for Candida infections (Table 1). All Candida infections were mild or moderate; none were systemic or led to study discontinuation. Over 156 weeks, the EAIR of inflammatory bowel disease (1.2), anterior uveitis (0.8), and injection site reactions (0.5) remained low. Efficacy demonstrated at Week 48 in BE AGILE was maintained or improved up to Week 156 (Figure 1). Mean ASDAS improved from 3.9 at BE AGILE baseline to 2.0 and 1.8 at Weeks 48 and 156 respectively (by MI). At Week 156 in the NRI analyses, ASAS40 and ASAS PR were achieved by 62.6% (OC: 72.6%) and 32.7% (OC: 37.9%) patients respectively. ASDAS-ID and ASDAS <2.1 responder rates (NRI) were maintained or continued to increase from Week 48, and by Week 156, responses were achieved by 28.0% (OC: 33.0%) and 57.1% (OC: 67.4%) patients respectively. ASDAS-MI responder rates (NRI) continued to increase from 44.9% at Week 48 to 46.5% at Week 156 (OC: 52.9%).

Table 1.

Safety for total exposure to BKZ across BE AGILE and the OLE

BE AGILEWeeks 0–48BE AGILE + OLEWeeks 0–156n (%) [EAIR/100 PY]BKZ 160 mg(n=149;114.2 PY)BKZ 320 mg(n=150;119.6 PY)All BKZ(N=303;261.3 PY)All BKZ(N=303;781.0 PY)Any TEAE103 (69.1) [168.7]122 (81.3) [221.1]235 (77.6) [186.2]280 (92.4) [143.5]Serious TEAEs5 (3.4) [4.4]6 (4.0) [5.1]13 (4.3) [5.1]43 (14.2) [5.8]Key TEAEs of special monitoringSerious infections3 (2.0) [2.7]1 (0.7) [0.8]4 (1.3) [1.5]10 (3.3) [1.3]Candida infections10 (6.7) [9.1]9 (6.0) [7.9]19 (6.3) [7.5]28 (9.2) [3.8]Inflammatory bowel disease1 (0.7) [0.9]2 (1.3) [1.7]4 (1.3) [1.5]9 (3.0) [1.2]Anterior uveitis1 (0.7) [0.9]1 (0.7) [0.8]2 (0.7) [0.8]6 (2.0) [0.8]Study discontinuations due to TEAEs7 (4.7)10 (6.7)20 (6.6)38 (12.5)Drug-related TEAEs48 (32.2)54 (36.0)110 (36.3)149 (49.2)Deaths1 (0.7)01 (0.3)2 (0.7)

TEAEs are reported for the BE AGILE safety set for total exposure to BKZ across BE AGILE and the OLE. There was one death in BE AGILE (cardiac arrest) and one in the OLE (road traffic accident); neither was considered treatment-related.

Conclusion:

The safety profile of BKZ in patients with AS was in line with previous observations.1.2 Patients treated with BKZ demonstrated sustained and consistent efficacy over 156 weeks.

References:

[1]van der Heijde D. Ann Rheum Dis 2020;79:595–604; 2. Baraliakos X. Arthritis Rheumatol 2020;72 (suppl 10).

Acknowledgements:

This study was funded by UCB Pharma. Editorial services were provided by Costello Medical.

Disclosure of Interests:

Désirée van der Heijde Consultant of: AbbVie, Amgen, Astellas, AstraZeneca, Bayer, BMS, Boehringer Ingelheim, Celgene, Cyxone, Daiichi, Eisai, Eli Lilly, Galapagos, Gilead, GSK, Janssen, Merck, Novartis, Pfizer, Regeneron, Roche, Sanofi, Takeda, UCB Pharma, Employee of: Director of Imaging Rheumatology, Atul Deodhar Speakers bureau: Janssen, Novartis, Pfizer, Consultant of: AbbVie, Amgen, BMS, Boehringer Ingelheim, Celgene, Eli Lilly, Gilead, GSK, Janssen, Novartis, Pfizer, UCB Pharma, Grant/research support from: AbbVie, Eli Lilly, GSK, Novartis, Pfizer, UCB Pharma, Lianne S. Gensler Consultant of: AbbVie, Eli Lilly, Gilead, GSK, Novartis, Pfizer, UCB Pharma, Grant/research support from: Pfizer, Denis Poddubnyy Speakers bureau: AbbVie, BMS, Eli Lilly, MSD, Novartis, Pfizer, UCB Pharma, Consultant of: AbbVie, Biocad, Eli Lilly, Gilead, GSK, MSD, Novartis, Pfizer, Samsung Bioepis, UCB Pharma, Grant/research support from: AbbVie, MSD, Novartis, Pfizer, Alan Kivitz Shareholder of: Pfizer, Novartis, Speakers bureau: Amgen, Eli Lilly, Pfizer, Novartis, Consultant of: Novartis, UCB Pharma, Maxime Dougados Consultant of: AbbVie, Eli Lilly, Novartis, Pfizer, UCB Pharma, Grant/research support from: AbbVie, Eli Lilly, Novartis, Pfizer, UCB Pharma, Natasha de Peyrecave Employee of: UCB Pharma, Marga Oortgiesen Employee of: UCB Pharma, Thomas Vaux Employee of: UCB Pharma, Carmen Fleurinck Employee of: UCB Pharma, Xenofon Baraliakos Speakers bureau: AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, MSD, Novartis, Pfizer, UCB Pharma, Paid instructor for: AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, MSD, Novartis, Pfizer, UCB Pharma, Consultant of: AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, MSD, Novartis, Pfizer, UCB Pharma

POS0919 BIMEKIZUMAB SHOWS SUSTAINED LONG-TERM IMPROVEMENTS IN PATIENT-REPORTED OUTCOMES AND QUALITY OF LIFE IN ANKYLOSING SPONDYLITIS: 3-YEAR RESULTS FROM A PHASE 2B STUDY

Background:

Bimekizumab (BKZ), a monoclonal antibody that selectively inhibits interleukin (IL)-17A and IL-17F, has demonstrated clinical efficacy and safety in patients with ankylosing spondylitis (AS) treated over a period up to 96 weeks.1,2

Objectives:

To report 3-year interim patient-reported outcomes (PROs) in patients with active AS treated with BKZ in a phase 2b dose-ranging study (BE AGILE; NCT02963506) and its open-label extension (OLE; NCT03355573).

Methods:

BE AGILE study design has been described previously.1 Patients treated with BKZ 160 mg or 320 mg every 4 weeks (Q4W) at Week 48 in BE AGILE were eligible for OLE entry. All OLE patients received BKZ 160 mg Q4W. Outcome measures are reported for the OLE full analysis set (patients who entered the OLE and had ≥1 dose of BKZ and ≥1 valid efficacy variable measurement in the OLE), and include: BASDAI, BASDAI50 responder rate, BASFI, fatigue (BASDAI Q1), morning stiffness (mean of BASDAI Q5 + 6), total spinal pain (numeric rating scale [NRS]), SF-36 PCS and MCS, and ASQoL. Missing data were imputed using multiple imputation (MI; based on the missing at random assumption) for continuous variables and non-responder imputation (NRI) for dichotomous variables.

Results:

262/303 (86%) patients randomised at BE AGILE study baseline (BL) completed Week 48 on BKZ 160 mg or 320 mg, of whom 255/262 (97%) entered the OLE (full analysis set: 254). From baseline to Week 48 in BE AGILE, BKZ-treated patients showed clinically relevant improvements in disease activity (BASDAI, BASDAI50), physical function (BASFI), fatigue, morning stiffness, spinal pain, and quality of life (SF-36 PCS and MCS, ASQoL) (Figure 1). Group-level improvements in all reported continuous efficacy measures exceeded published minimally important difference (MID), minimum clinically important improvement (MCII), and/or minimum clinically important difference (MCID) thresholds (Figure 1).3,4 Efficacy in all reported outcome measures was maintained or continued to improve from Week 48 to Week 144 or 156 (Figure 1).

Conclusion:

BKZ treatment was associated with sustained and consistent efficacy in patients with active AS over 3 years, including patient-reported disease activity, physical function, fatigue, morning stiffness, spinal pain, and quality of life.

References:

[1]van der Heijde D. Ann Rheum Dis 2020;79:595–604.

[2]Baraliakos X. Arthritis Rheumatol 2020;72 (suppl 10).

[3]Ogdie A. Arthritis Care Res 2020;72 (S10):47–71.

[4]Maruish ME. User’s manual for the SF-36v2 Health Survey (3rd ed). 2011; Lincoln, RI: QualityMetric Incorporated.

Acknowledgements:

This study was funded by UCB Pharma. Editorial services were provided by Costello Medical.

Disclosure of Interests:

Xenofon Baraliakos Speakers bureau: AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, MSD, Novartis, Pfizer, UCB Pharma, Paid instructor for: AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, MSD, Novartis, Pfizer, UCB Pharma, Consultant of: AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, MSD, Novartis, Pfizer, UCB Pharma, Maxime Dougados Consultant of: AbbVie, Eli Lilly, Novartis, Pfizer and UCB Pharma, Grant/research support from: AbbVie, Eli Lilly, Novartis, Pfizer and UCB Pharma, Karl Gaffney Speakers bureau: AbbVie, Eli Lilly, Novartis, UCB Pharma, Consultant of: AbbVie, Eli Lilly, Novartis, UCB Pharma, Grant/research support from: AbbVie, Gilead, Eli Lilly, Novartis, UCB Pharma, Raj Sengupta Speakers bureau: AbbVie, Biogen, Celgene, MSD, Novartis, UCB Pharma, Consultant of: AbbVie, Biogen, Celgene, Eli Lilly, MSD, Novartis, UCB Pharma, Grant/research support from: AbbVie, Celgene, UCB Pharma, Marina Magrey Consultant of: AbbVie, Eli Lilly, Novartis, Pfizer, UCB Pharma, Grant/research support from: AbbVie, UCB Pharma, Natasha de Peyrecave Employee of: UCB Pharma, Marga Oortgiesen Employee of: UCB Pharma, Thomas Vaux Employee of: UCB Pharma, Carmen Fleurinck Employee of: UCB Pharma, Valerie Ciaravino Employee of: UCB Pharma, Atul Deodhar Speakers bureau: Janssen, Novartis, Pfizer, Consultant of: AbbVie, Amgen, BMS, Boehringer Ingelheim, Celgene, Eli Lilly, Gilead, GSK, Janssen, Novartis, Pfizer, UCB Pharma, Grant/research support from: AbbVie, Eli Lilly, GSK, Novartis, Pfizer, UCB Pharma

Direct Functional Effects of Parathion and Paraoxon on Neuronal Nicotinic and Muscarinic M3 Acetylcholine Receptors

The direct effects of two organophosphates, parathion and paraoxon, on nicotinic and muscarinic acetylcholine receptors in cells from different species were investigated, by using the whole-cell voltage clamp technique. The effects of neuronal type nicotinic receptors in mouse N1E-115, human SH-SY5Y and locust thoracic ganglion cells, and on human muscarinic M3 receptors transfected in Chinese hamster ovary (CHO) cells, were analysed. Parathion and paraoxon inhibit acetylcholine-induced nicotinic inward currents at concentrations in the micromblar range. Surprisingly, parathion is a more potent inhibitor than its active acetyl-cholinesterase-inhibiting metabolite, paraoxon. Moderate differences in sensitivity to the blocking action of the organophosphates appear to exist between cells from different species. Both parathion (100nM) and paraoxon (1μM) induce ion currents in M3-transfected CHO cells. They appear to act as agonists on the human muscarinic M3 receptor, affecting the receptors in a different manner to that of acetylcholine.

Nicotinic Receptors of Different Species Exhibit Differential Sensitivities to Nitromethylene and Organophosphate Insecticides

The effects of nitromethylene heterocycle (NMH) and organophosphate (OP) insecticides were studied on nicotinic acetylcholine receptors (nAChR) in cultured cells of different species origin, in order to examine the selectivity of these compounds at the level of the target sites. In mouse muscle BC3H1, mouse NIE-115 and human SH-SY5Y neuroblastoma, and locust thoracic ganglion cells, the neurotransmitter, acetylcholine (ACh), induces a similar transient inward current. Dependent on the cell type, the six NMHs acted as agonists and/or antagonists on nAChR. Distinct agonistic effects of NMHs on nAChR are observed on insect neurons only. Further, NMHs potently block nicotinic responses in insects, while mammalian cells are only moderately affected. In all cases, the neuronal type nAChR was more sensitive to blocking than the endplate type nAChR in mammalian cells.

Parathion and paraoxon at micromolar concentrations inhibit ACh-induced nicotinic inward currents. The insecticide, parathion, is a 50-fold more potent inhibitor than its acetyl-cholinesterase-inhibiting metabolite, paraoxon. Moderate differences in sensitivity to the blocking action of the OPs appear to exist among cells of different species. The results demonstrate that the experimental approach of fundamental electrophysiology and the use of cell lines are relevant tools for investigating the species specificity of neurotoxic compounds.

OP0105 EFFICACY AND SAFETY OF BIMEKIZUMAB IN ANKYLOSING SPONDYLITIS: 48-WEEK PATIENT-REPORTED OUTCOMES FROM A PHASE 2B, RANDOMISED, DOUBLE-BLIND, PLACEBO-CONTROLLED, DOSE-RANGING STUDY

Background:

Bimekizumab (BKZ), a monoclonal antibody that selectively neutralises interleukin (IL)-17A and IL-17F, is a potential therapeutic option in ankylosing spondylitis (AS).

Objectives:

To report 48-week (wk) patient-reported outcomes (PROs) in patients (pts) with AS treated with BKZ in a phase 2b dose-ranging study (BE-AGILE;NCT02963506).

Methods:

Pts with active AS (Bath AS Disease Activity Index [BASDAI] ≥4; spinal pain ≥4 [0–10]), fulfilling modified New York criteria (central reading), and inadequate response/intolerance to NSAIDs were randomised according to the study design (Figure 1). PROs included spinal pain, fatigue (BASDAI Q1), morning stiffness (mean of BASDAI Q5 + 6), Bath AS Functional Index (BASFI), Medical Outcomes Study (MOS) Sleep Problems Index II and AS Quality of Life questionnaire (ASQoL). Efficacy is reported for pts initially randomised to placebo (PBO) or BKZ 160/320 mg every 4 weeks (Q4W); treatment-emergent adverse events (TEAEs) are reported for pts who received ≥1 dose of study drug (Safety Set).

Results:

Of 303 pts, 181 were randomised to PBO or BKZ 160/320 Q4W mg at Wk 0; 179/181 completed Wk 12 and 161/181 completed Wk 48. At Wk 12, improvements in pain, fatigue, morning stiffness, BASFI, sleep and ASQoL were greater in BKZ pts vs PBO pts. Responses were further improved or maintained to Wk 48, with no meaningful differences between BKZ 160 mg and 320 mg (Table 1). Serious TEAEs occurred in 13/303 (4.3%) pts (Table 2), which included 2 major adverse cardiac events considered not related to study drug. Oral candidiasis occurred in 16 (5.3%) pts.

Table 1.

PRO efficacy endpoints to Week 48 (multiple imputation)

Mean (SD)WkPBO – BKZ 160 mg(n=24)PBO – BKZ 320 mg(n=36)BKZ 160 mg(n=58)BKZ 320 mg(n=61)Spinal pain06.9 (1.4)7.0 (1.9)6.6 (2.0)7.3 (1.5)CfB12-1.5 (1.6)-0.7 (1.7)-2.6 (2.2)-3.6 (2.4)48-3.7 (2.0)-3.7 (2.6)-3.8 (2.4)-4.7 (2.1)Fatigue06.4 (1.7)6.8 (1.6)6.4 (1.7)6.4 (1.9)CfB12-0.7 (2.5)-1.0 (1.7)-2.1 (2.2)-2.1 (2.5)48-2.7 (2.2)-2.8 (2.4)-3.1 (2.1)-3.3 (2.4)Morning stiffness06.9 (1.7)6.7 (2.0)6.5 (1.8)6.6 (2.1)CfB12-1.5 (1.7)-1.1 (1.5)-2.8 (2.0)-3.4 (2.7)48-3.9 (2.2)-3.6 (2.4)-3.9 (2.2)-4.4 (2.4)BASFI05.8 (1.8)5.5 (2.2)5.5 (2.2)5.9 (2.0)CfB12-1.0 (2.1)-0.3 (1.7)-1.7 (1.8)-2.2 (2.0)48-2.9 (2.2)-2.4 (2.2)-2.5 (2.0)-2.9 (2.2)MOS Sleep Problems Index II045.5 (8.1)45.3 (7.9)46.9 (7.5)47.2 (9.4)CfB122.1 (8.3)1.8 (6.8)5.6 (6.7)6.8 (7.5)487.6 (8.7)8.0 (9.1)6.5 (6.1)8.0 (7.9)ASQoL08.4 (4.7)9.2 (4.7)8.4 (4.3)8.7 (4.3)CfB12-1.3 (5.5)-1.3 (3.7)-3.5 (4.3)-4.6 (4.8)48-4.2 (5.6)-5.3 (5.6)-4.9 (4.1)-5.4 (4.8)

CfB: change from baseline

Table 2.

Overview of TEAEs to Week 48 (Safety Set; N=303)

n (%)BKZ 160 mg(n=149)BKZ 320 mg(n=150)All BKZ [a](N=303)Any TEAE103 (69.1)122 (81.3)235 (77.6)Drug-related TEAEs48 (32.2)54 (36.0)110 (36.3)Serious TEAEs5 (3.4)6 (4.0)13 (4.3)Discontinuations due to TEAEs7 (4.7)10 (6.7)20 (6.6)

[a] Includes TEAEs for 16 and 64 mg BKZ

Conclusion:

Pts with active AS demonstrated rapid and sustained improvements in PROs, sleep and quality of life over 48 wks of BKZ treatment. BKZ was generally well tolerated with no unexpected safety findings versus previous studies.

Acknowledgments:

This study was funded by UCB Pharma. Editorial services were provided by Costello Medical.

Disclosure of Interests:

Désirée van der Heijde Consultant of: AbbVie, Amgen, Astellas, AstraZeneca, BMS, Boehringer Ingelheim, Celgene, Cyxone, Daiichi, Eisai, Eli-Lilly, Galapagos, Gilead Sciences, Inc., Glaxo-Smith-Kline, Janssen, Merck, Novartis, Pfizer, Regeneron, Roche, Sanofi, Takeda, UCB Pharma; Director of Imaging Rheumatology BV, Lianne S. Gensler Grant/research support from: Pfizer, Novartis, UCB, Consultant of: AbbVie, Eli Lilly, GSK, Novartis, UCB, Atul Deodhar Grant/research support from: AbbVie, Eli Lilly, GSK, Novartis, Pfizer, UCB, Consultant of: AbbVie, Amgen, Boehringer Ingelheim, Bristol Myer Squibb (BMS), Eli Lilly, GSK, Janssen, Novartis, Pfizer, UCB, Speakers bureau: AbbVie, Amgen, Boehringer Ingelheim, Bristol Myer Squibb (BMS), Eli Lilly, GSK, Janssen, Novartis, Pfizer, UCB, Xenofon Baraliakos Grant/research support from: Grant/research support from: AbbVie, BMS, Celgene, Chugai, Merck, Novartis, Pfizer, UCB and Werfen, Consultant of: AbbVie, BMS, Celgene, Chugai, Merck, Novartis, Pfizer, UCB and Werfen, Speakers bureau: AbbVie, BMS, Celgene, Chugai, Merck, Novartis, Pfizer, UCB and Werfen, Denis Poddubnyy Grant/research support from: AbbVie, MSD, Novartis, and Pfizer, Consultant of: AbbVie, Bristol-Myers Squibb, Eli Lilly, MSD, Novartis, Pfizer, Roche, UCB, Speakers bureau: AbbVie, Bristol-Myers Squibb, Eli Lilly, MSD, Novartis, Pfizer, Roche, UCB, Alan Kivitz Shareholder of: AbbVie, Amgen, Gilead, GSK, Pfizer Inc, Sanofi, Consultant of: AbbVie, Boehringer Ingelheim, Flexion, Genzyme, Gilead, Janssen, Novartis, Pfizer Inc, Regeneron, Sanofi, SUN Pharma Advanced Research, UCB, Paid instructor for: Celgene, Genzyme, Horizon, Merck, Novartis, Pfizer, Regeneron, Sanofi, Speakers bureau: AbbVie, Celgene, Flexion, Genzyme, Horizon, Merck, Novartis, Pfizer Inc, Regeneron, Sanofi, Mary Katherine Farmer Employee of: UCB Pharma, Dominique Baeten Employee of: UCB Pharma, Nadine Goldammer Employee of: UCB Pharma, Jason Coarse Employee of: UCB Pharma, Marga Oortgiesen Employee of: UCB Pharma, Maxime Dougados Grant/research support from: AbbVie, Eli Lilly, Merck, Novartis, Pfizer and UCB Pharma, Consultant of: AbbVie, Eli Lilly, Merck, Novartis, Pfizer and UCB Pharma, Speakers bureau: AbbVie, Eli Lilly, Merck, Novartis, Pfizer and UCB Pharma

Dual neutralisation of interleukin-17A and interleukin-17F with bimekizumab in patients with active ankylosing spondylitis: results from a 48-week phase IIb, randomised, double-blind, placebo-controlled, dose-ranging study

OBJECTIVES

Bimekizumab selectively neutralises both interleukin (IL)-17A and IL-17F. We report efficacy and safety in a phase IIb dose-ranging study in patients with active ankylosing spondylitis (AS).

METHODS

Adults with AS (fulfilling modified New York criteria) were randomised 1:1:1:1:1 to bimekizumab 16 mg, 64 mg, 160 mg, 320 mg or placebo every 4 weeks for 12 weeks (double-blind period). At week 12, patients receiving bimekizumab 16 mg, 64 mg or placebo were re-randomised 1:1 to bimekizumab 160 mg or 320 mg every 4 weeks to week 48; other patients continued on their initial dose (dose-blind period). The primary end point was Assessment of SpondyloArthritis international Society (ASAS) 40 response at week 12 (non-responder imputation (NRI) for missing data).

RESULTS

303 patients were randomised: bimekizumab 16 mg (n=61), 64 mg (n=61), 160 mg (n=60), 320 mg (n=61) or placebo (n=60). At week 12, significantly more bimekizumab-treated patients achieved ASAS40 vs placebo (NRI: 29.5%-46.7% vs 13.3%; p<0.05 all comparisons; OR vs placebo 2.6-5.5 (95% CI 1.0 to 12.9)). A significant dose-response was observed (p<0.001). The primary end point was supported by all secondary efficacy outcomes. At week 48, 58.6% and 62.3% of patients receiving bimekizumab 160 and 320 mg throughout the study achieved ASAS40, respectively (NRI); similar ASAS40 response rates were observed in re-randomised patients. During the double-blind period, treatment-emergent adverse events occurred in 26/60 (43.3%) patients receiving placebo and 92/243 (37.9%) receiving bimekizumab.

CONCLUSIONS

Bimekizumab provided rapid and sustained improvements in key outcome measures in patients with active AS, with no unexpected safety findings versus previous studies.

TRIAL REGISTRATION NUMBER

NCT02963506.

Randomized, double-blind, crossover study of the adhesiveness of two formulations of rotigotine transdermal patch in patients with Parkinson's disease

OBJECTIVE

In patch-based transdermal drug delivery, adhesiveness is critical for safe and effective treatment, especially in Parkinson's disease (PD) where excessive sweating is common. This study compared the adhesiveness of two transdermal patch formulations of rotigotine (improved room temperature-stable [PR2.3.1/Treatment A] and intermediate cold storage product [PR2.1.1/Treatment B]), using the largest patch size (40 cm²).

METHODS

PD0018 (NCT02230904) was a multicenter, randomized, double-blind, crossover study. PD patients received Treatments A and B in randomized order for 2 days each. Patch adhesiveness was measured immediately after patch application and 24 hours thereafter (before removal). Primary variable: change in average investigator-rated adhesiveness score between treatments, per modified European Medicines Agency scale (EMA/CHMP/QWP/911254/2011, 2012).

RESULTS

Fifty-seven patients were randomized; 56 patients completed the study. Five patients were excluded from analysis for accidental unblinding. Treatment A had better average adhesiveness score (mean ± SD Treatment A - Treatment B: 1.115 ± 1.635). A higher percentage of patients on both days had patch adhesiveness ≥95% at 24 hours for Treatment A (first day: 65.4%, second day: 71.2%) vs. Treatment B (46.2%, 36.5%), and were satisfied with patch adhesiveness of Treatment A (first day: 75.0%, second day: 73.1%) vs. Treatment B (65.4%, 59.6%). Average patch-wear duration was similar between formulations (23.761 hours vs. 23.495 hours per patch). Both formulations were well tolerated with no new safety observations.

CONCLUSION

Results indicated greater adhesiveness for the improved room temperature-stable formulation (PR2.3.1) vs. intermediate cold storage product (PR2.1.1) using the largest patch-size, with comparable safety and skin tolerability.

Efficacy of Epratuzumab, an Anti-CD22 Monoclonal IgG Antibody, in Systemic Lupus Erythematosus Patients With Associated Sjögren's Syndrome: Post Hoc Analyses From the EMBODY Trials

OBJECTIVE

EMBODY 1 (ClinicalTrials.gov identifier: NCT01262365) and EMBODY 2 (ClinicalTrials.gov identifier: NCT01261793) investigated the efficacy and safety of epratuzumab, a CD22-targeted humanized monoclonal IgG antibody, in patients with systemic lupus erythematosus (SLE). The studies showed no significant difference from placebo in primary or secondary clinical outcome measures but did demonstrate B cell-specific immunologic activity. The aim of this post hoc analysis was to determine whether epratuzumab had a different clinical efficacy profile in SLE patients with versus those without an associated diagnosis of Sjögren's syndrome (SS).

METHODS

The efficacy and safety of epratuzumab were compared between 2 patient subpopulations randomized in EMBODY 1 and 2: SLE patients with and those without a diagnosis of associated SS. British Isles Lupus Assessment Group (BILAG) total score, BILAG-based Combined Lupus Assessment (BICLA) clinical response to treatment, biologic markers (including B cells, IgG, IgM, and IgA), and safety were assessed.

RESULTS

A total of 1,584 patients were randomized in the EMBODY 1 and EMBODY 2 trials; 113 patients were anti-SSA positive and had a diagnosis of associated SS, and 1,375 patients (86.8%) had no diagnosis of associated SS (918 patients were randomized to receive epratuzumab and 457 to receive placebo). For patients with associated SS, but not those without associated SS, a higher proportion of patients receiving epratuzumab achieved a BICLA response and a reduction from baseline in BILAG total score. B cell reduction was faster in patients with associated SS. The sensitivity of B cells to epratuzumab as measured by the mean concentration producing 50% of the maximum B cell count depletion was lower for patients with associated SS (9.5 μg/ml) versus the total EMBODY population (87.1 μg/ml). No difference in the frequency of adverse events in those receiving placebo was reported.

CONCLUSION

Patients with SLE and associated SS treated with epratuzumab showed improvement in SLE disease activity, which was associated with bioactivity, such as decreases in B cell number and IgM level.

An open-label, multinational, multicenter study of G17DT vaccination combined with cisplatin and 5-fluorouracil in patients with untreated, advanced gastric or gastroesophageal cancer: the GC4 study

BACKGROUND

Gastrin hormone is trophic to in vitro gastric cancer, and the antigastrin antibodies (AGAs) are antiproliferative and antimetastatic. Human gastric cancers overexpress gastrin genes and receptors that react to gastrin's trophic effects. Immunogen G17DT elicits a specific and high-affinity AGA. The authors evaluated G17DT vaccination given with cisplatin plus 5-fluorouracil for the treatment gastric adenocarcinoma.

METHODS

In this multicenter, Phase II study, patients received G17DT vaccination intramuscularly on Weeks 1, 5, 9 and 25 and cisplatin plus 5-fluorouracil every 28 days. Eligible patients had untreated, metastatic, or unresectable gastric or gastroesophageal adenocarcinoma with near-normal organ function. The primary endpoint of the study was the over response rate (ORR), and secondary endpoints included overall survival (OS), safety, and the impact of successful vaccination on patient outcome.

RESULTS

In total, 103 patients were enrolled in 5 countries. Seven patients who were overdosed inadvertently with 5-fluorouracil (a major protocol violation) were removed from the analysis. The confirmed ORR was 30% in 79 patients who were evaluated for response. The median time-to-progression (TTP) was 5.4 months, and the median survival (MS) was 9.0 months (n = 96 patients). Sixty-five of 94 patients who were vaccinated (69%) had 2 consecutive AGA titers of > or =1 units (successfully vaccinated patients or immune-responders). The TTP was longer in immune-responders than in immune-nonresponders (P = .0005). Similarly, the MS was longer in immune-responders than in immune-nonresponders (10.3 months vs. 3.8 months; P < or =.0001). In a multivariate analysis, successful vaccination was an independent OS prognosticator (P = .0001). G17DT did not have an adverse effect on safety.

CONCLUSIONS

The results demonstrated that successful G17DT vaccination was correlated with longer TTP and MS. AGA response was an independent OS prognosticator. A Phase III evaluation of G17DT in gastric cancer is warranted.

The TRPV1 Receptor: Target of Toxicants and Therapeutics

Understanding the structural and functional complexities of the transient receptor potential vanilloid receptor (TRPV1) is essential to the therapeutic modulation of inflammation and pain. Because of its central role in initiating inflammatory processes and integrating painful stimuli, there is an understandable interest in its pharmacological manipulation (sensitization/desensitization). The present Highlight entitled "TRPV1 antagonists elevate cell surface populations of receptor protein and exacerbate TRPV1 mediated toxicities in human lung epithelial cells" describes how exposure to various antagonists produces TRPV1 sensitization and proposes a possible mechanistic explanation to that sensitization.

Electrostatic charge activates inflammatory vanilloid (VR1) receptors

The pathophysiology of neurogenic inflammation culminates in the overt symptoms of tissue inflammation through a series of events which are initiated by the activation of vanilloid receptors (VR1). This study was designed to test the hypothesis that a sufficiently negative, electrostatic charge carried on a particulate matter (PM) particle, could acquire a cloud of protons sufficient to activate proton-sensitive VR1 receptors and acid-sensitive ionic channels (ASICs) pathways. For this, nanometer-sized, synthetic polystyrene micells (SPM) or those charged with chemical groups (e.g. diamino, carboxyl) were used. These chemical groups imparted either a net positive (i.e. diamino) or negative (i.e. carboxyl) charge on the SPM when suspended in a neutral ionic medium. The zeta potential, a measure of the SPM's electronegativity, was taken in both cell culture nutrient medium and in ultraviolet light-distilled water (UV-DW). In both vehicles, the rank order of electronegativity (most to least negative) was carboxyl > polystyrene > diamino-SPM. Individual types of SPM were exposed to human, immortalized bronchial-tracheal epithelial cells (i.e. BEAS-2B) and endpoints of biological activation (i.e. membrane depolarization, increases in intracellular calcium (i.e. [Ca(2+)](i)) levels, IL-6 release) were measured. Cells loaded with a fluorescent probe for membrane depolarization (3,3'-dihexyloxacarbocyanine iodide, DiOC-6-3) showed a positive reaction when exposed to carboxyl-SPM but not to diamino-SPM. BEAS-2B cells exposed to carboxyl-SPM responded with significant increases in [Ca(2+)](i), and IL-6 release relative to uncharged SPM or diamino-SPM. This IL-6 release could be reduced by pretreatment with antagonists to the VR1 receptor (i.e. capsazepine) or to acid-sensitive ionc channels (i.e. amiloride). Although both diamino and carboxyl-SPM groups stimulated increases in IL-6 transcript, only the more electronegatively charged carboxyl-SPM stimulated mRNA-VR1 receptor. These data suggest that measurable inflammatory changes can be stimulated in human epithelial target cells by the electrostatic charge carried on an inert particle. Further, these changes appear to be mediated through acid-sensitive VR1 receptors and ASICs.

The surface charge of visible particulate matter predicts biological activation in human bronchial epithelial cells

The physicochemical complexity of airborne particulate matter (PM) has hampered identifying a specific mechanism(s) for its toxicity. In this study, selected physicochemical characteristics (i.e., size, particle number, acidity, and surface charge) were measured on various field PM, derived from urban ambient (St. Louis, Ottawa, Canada), residential (Woodstove), volcanic dust from Mt. St. Helen (MSH), and industrial [oil fly ash (OFA) coal fly ash (CFA)] sources. Morphometric analysis of visible (< or = 2.0 to >10 microm) field particles indicated that the industrial PM (OFA, CFA) had the smallest diameter and lowest total number of particles per weight while Woodstove and Ottawa had the largest diameter and highest number of particles. All PM lowered the pH of an unbuffered 10 mM NaCl solution from pH 7.4 to pH 4.7-6.8 but did not change the neutral pH of the cell culture medium, keratinocyte growth media (KGM). The surface charge (i.e., zeta potential) of microscopically visible (> or = 2.0 microm) field particles, suspended in either a Hepes-buffered KCl solution or in KGM, was measured by microelectrophoresis. In KCl solution, the mean zeta potential of all tested PM ranged from -36 +/- 2 (Woodstove) to -27 +/- 4.3 mV (MSH). When measured in KGM medium, the mean zeta potential value of each PM was significantly less (p > 0.001) than those measured in KCl solution, with values ranging from -17 +/- 0.3 mV (St. Louis) to -9 +/- 0.6 mV (MSH). Suspensions of field PM, its soluble and washed particulate fractions, were next prepared from each PM. The biological effects (i.e., increases in intracellular calcium ([Ca2+]i), cytokine release) of their exposure were measured in human, immortalized, tracheal-bronchial epithelial cells (BEAS-2B). Exposure of BEAS-2B cells to each fraction produced an immediate, but differential increase in [Ca2+]i and the subsequent release of the inflammatory cytokine IL-6, 4 and 16 h later. Increases in [Ca2+]i by field PM significantly correlated with the IL-6 released by each fraction (r2 > or = 0.76) after both 4 and 16 h exposures. The biological effects of each PM were compared with their physicochemical characteristics. No correlation was found between increases in [Ca2+]i or cytokine release and a PM's acidity or the number or size of its visible (> or = 2.0 microm) particles. However, the surface charge of PM field particles, when measured in the KGM exposure medium, showed a high correlation (r2 > or = 0.94) with the IL-6 release by field PM after both 4 and 16 h exposure. Increases in [Ca2+]i also correlated (r2 = 0.85) with the surface charge of PM field particles when measured in KGM. These data indicate that the surface charge (i.e., zeta potential) carried on PM's visible field particles predicts their differential release of the inflammatory cytokine IL-6 in cultures of human respiratory epithelial cells.

Particulate matter inflammation and receptor sensitivity are target cell specific

The complexity of primary source particulate matter (PM) and the various cell types encountered by its inhalation raise the possibility that target cells are differentially activated. Since epithelial cells, which line the nasal-tracheal-bronchial airways, and sensory C fibers, which terminate throughout this epithelial layer, are initially targeted by inhaled PM, we compared their relative biological response in vitro to PM originating from volcanic (MSH), anthropogenic (diesel), residential (woodstove), urban ambient (St. Louis, Ottawa), and industrial emission (coal fly ash, CFA; residual oil fly ash, ROFA; oil fly ash, OFA) sources. Increases in intracellular calcium (i.e., [Ca(2+)](i)) are a second-messenger event that indicates cellular activation and signal transduction, in both nerve and epithelial cells. Single-cell calcium imaging recordings were taken of human bronchial epithelial cells (BEAS-2B) exposed to selected PM (50 microg/ml or 30 microg/cm(2)). These cells responded with variable increases in [Ca(2+)](i) ranging from abrupt increases, which returned to baseline upon washing of the cells, to oscillations of the [Ca(2+)](i) that did not wash out. Increases in [Ca(2+)](i) and inflammatory cytokine (i.e., interleukin 6, IL-6) release were measured in populations of BEAS-2B cells exposed to PM (50 microg/ml) and were shown to significantly correlate (r(2) =.80). BEAS-2B cells, stained histochemically with cobalt, displayed a concentration-dependent precipitation in response to acid pH and capsaicin, indicating the presence of acid-sensitive pathways (e.g., VR1 and acid-sensitive receptors). To demonstrate the relevance of these pathways to inflammatory cytokine (i.e., IL-6) release, BEAS-2B cells were pretreated (15 min) with antagonists to the vanilloid (VR1) receptor (i.e., capsazepine, CPZ) or acid-sensitive pathways (i.e., amiloride) before their exposure to the selected PM. A significant reduction of IL-6 release occurred in response to all PM, except for MSH and diesel exhaust. Dorsal root ganglia (DRG), which innervate the tracheal airways, were dissociated from fetal mice and pretreated with CPZ or amiloride before exposure (4 h) to the selected PM (50 microg/ml). Overall, significantly higher release occurred in PM-exposed sensory neurons relative to that of BEAS-2B epithelial cells. Although both CPZ and amiloride significantly reduced IL-6 release for all PM, the degree of inhibition was less for the PM-exposed DRG relative to BEAS-2B cells. These data show that differential increases in [Ca(2+)](i) and IL-6 release occur in BEAS-2B epithelial cells and DRG sensory neurons, when exposed to PM derived from different sources. The degree of this activation, however, depends not only on the source of the PM, but also on its cellular target. This differential sensitivity of target cells may contribute to the organism's overall inflammatory response to PM exposure.

Neurogenic inflammation and particulate matter (PM) air pollutants

Exposure to a class of airborne pollutants known as particulate matter (PM) is an environmental health risk of global proportions. PM is thought to initiate and/or exacerbate respiratory disorders, such as asthma and airway hyper-responsiveness and is epidemiologically associated with causing death in the elderly and those with pre-existing respiratory, or cardiopulmonary disease. Plausible mechanisms of action to explain PM inflammation and its susceptible sub-population component are lacking. This review describes a series of published studies which indicate that PM initiates airway inflammation through sensory neural pathways, specifically by activation of capsaicin-sensitive vanilloid (e.g. VRI) irritant receptors. These acid-sensitive receptors are located on the sensory C nerve fibers that innervate the airways as well as on various immune and non-immune airway target cells. The activation of these receptors results in the release of neuropeptides from the sensory terminals that innervate the airways. Their interactions with airway target cells, result in signs of inflammation (e.g. bronchoconstriction, vasodilation, histamine release, mucous secretion etc.). Our data have linked the activation of the VR1 receptors to the surface charge carried on the colloidal particulates which constitute PM pollution. Related studies have examined how genetic and non-genetic factors modify the sensitivity of these irritant receptors and enhance the inflammatory responsiveness to PM. In summary, this review proposes a mechanism by which neurogenic elements initiate and sustain PM-mediated airway inflammation. Although neurogenic influences have been appreciated in normal airway homeostasis, they have not, until now, been associated with PM toxicity. The sensitivity of the sensory nervous system to irritants and its interactions with pulmonary target tissues, should encourage neuroscientists to explore the relevance of neurogenic influences to toxic disorders involving other peripheral target systems.

Capsaicin inhibits activation of voltage-gated sodium currents in capsaicin-sensitive trigeminal ganglion neurons

Capsaicin, the pungent ingredient in hot pepper, activates nociceptors to produce pain and inflammation. However, repeated exposures of capsaicin will cause desensitization to nociceptive stimuli. In cultured trigeminal ganglion (TG) neurons, we investigated mechanisms underlying capsaicin-mediated inhibition of action potentials (APs) and modulation of voltage-gated sodium channels (VGSCs). Capsaicin (1 microM) inhibited APs and VGSCs only in capsaicin-sensitive neurons. Repeated applications of capsaicin produced depolarizing potentials but failed to evoke APs. The capsaicin-induced inhibition of VGSCs was prevented by preexposing the capsaicin receptor antagonist, capsazepine (CPZ). The magnitude of the capsaicin-induced inhibition of VGSCs was dose dependent, having a K(1/2) = 0.45 microM. The magnitude of the inhibition of VGSCs was proportional to the capsaicin induced current (for -I(CAP) < 0.2 nA). Capsaicin inhibited activation of VGSCs without changing the voltage dependence of activation or markedly changing channel inactivation and use-dependent block. To explore the changes leading to this inhibition, it was found that capsaicin increased cAMP with a K(1/2) = 0.18 microM. At 1 microM capsaicin, this cAMP generation was inhibited 64% by10 microM CPZ, suggesting that activation of capsaicin receptors increased cAMP. The addition of 100 microM CPT-cAMP increased the capsaicin-activated currents but inhibited the VGSCs in both capsaicin-sensitive and -insensitive neurons. In summary, the inhibitory effects of capsaicin on VGSCs and the generation of APs are mediated by activation of capsaicin receptors. The capsaicin-induced activation of second messengers, such as cAMP, play a part in this modulation. These data distinguish two pathways by which neuronal sensitivity can be diminished by capsaicin: by modulation of the capsaicin receptor sensitivity, since the block of VGSCs is proportional to the magnitude of the capsaicin-evoked currents, and by modulation of VGSCs through second messengers elevated by capsaicin receptor activation. These mechanisms are likely to be important in understanding the analgesic effects of capsaicin.

Vanilloid (capsaicin) receptors influence inflammatory sensitivity in response to particulate matter

The signs of airway inflammation and hyperresponsiveness that occur in animals exposed to air pollutants are often strain- and species-specific. To investigate the underlying causes of this phenomenon, BALB/c and C57bl/6 mice were exposed intratracheally to residual oil fly ash (ROFA, 3 mg/kg) and examined after 24 h for signs of airway inflammation. BALB/c showed significantly higher numbers of neutrophils and increased airway hyperresponsiveness in response to methacholine challenge, whereas B6 mice showed no significant change in either inflammatory endpoint. To determine the underlying cause of this strain specificity, cultures of dorsal root ganglion (DRG) sensory neurons, which innervate the upper airways in situ, were explanted from both BALB/c and B6 fetal mice. After 5-7 days in culture, they were exposed to ROFA, other urban and industrial particulate matter (PM; e.g., oil fly ash, woodstove, Mt. St. Helen, St. Louis, Ottawa, coal fly ash) or to prototype irritants (e.g., capsaicin 3-10 microM, pH 5.0 and 6.5). In all instances (except for woodstove), DRG neurons from BALB/c mice released significantly higher levels of the pro-inflammatory cytokine IL-6 into their nutrient media relative to neurons from B6 mice. This cytokine release could be significantly reduced for all PM treated cultures (except woodstove) by pretreatment of cultures with capsazepine (CPZ), a competitive antagonist of vanilloid receptors. DRG neurons, cultured from BALB/c and B6 neonates, were loaded with Fluo-3 AM and exposed to the prototype irritants, acid pH (5.0, 6.5), or capsaicin (3, 10 microM). Analysis of their increases in intracellular calcium showed that significantly higher numbers of BALB/c neurons responded to these prototype irritants, relative to B6 neurons. Morphometric analysis of BALB/c neurons, histochemically stained with cobalt to label neurons bearing capsaicin-sensitive receptors, showed a significantly higher level of stained neurons relative to B6 neurons. Finally, semiquantitative RT-PCR showed a higher expression of VR1 receptor mRNA in DRG and spinal cord taken from neonatal BALB/c mice relative to B6 mice. Taken together, these data suggest that capsaicin and acid-sensitive irritant receptors, located on somatosensory cell bodies and their nerve fiber terminals, subserve PM-induced airway inflammation and are quantitatively different in responsive and nonresponsive mouse strains.

Residual oil fly ash and charged polymers activate epithelial cells and nociceptive sensory neurons

Residual oil fly ash (ROFA) is an industrial pollutant that contains metals, acids, and unknown materials complexed to a particulate core. The heterogeneous composition of ROFA hampers finding the mechanism(s) by which it and other particulate pollutants cause airway toxicity. To distinguish culpable factors contributing to the effects of ROFA, synthetic polymer microsphere (SPM) analogs were synthesized that resembled ROFA in particle size (2 and 6 microm in diameter) and zeta potential (-29 mV). BEAS-2B human bronchial epithelial cells and dorsal root ganglion neurons responded to both ROFA and charged SPMs with an increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) and the release of the proinflammatory cytokine interleukin-6, whereas neutral SPMs bound with polyethylene glycol (0-mV zeta potential) were relatively ineffective. In dorsal root ganglion neurons, the SPM-induced increases in [Ca(2+)](i) were correlated with the presence of acid- and/or capsaicin-sensitive pathways. We hypothesized that the acidic microenvironment associated with negatively charged colloids like ROFA and SPMs activate irritant receptors in airway target cells. This causes subsequent cytokine release, which mediates the pathophysiology of neurogenic airway inflammation.

Neuropeptides and capsaicin stimulate the release of inflammatory cytokines in a human bronchial epithelial cell line

The role of neuropeptides in initiating and modulating airway inflammation was examined in a human bronchial epithelial cell line (i.e. BEAS-2B). At a range of concentrations, exposure of BEAS-2B cells to Substance P (SP) or calcitonin gene related protein resulted in immediate increases in intracellular calcium ([Ca(2+)](i)), the synthesis of the transcripts for the inflammatory cytokines, IL-6, IL-8 and TNFalpha after 2 h exposure, and the release of their proteins after 6 h exposure. Addition of thiorphan (100 nM), an inhibitor of neutral endopeptidase, enhanced the levels of SP-stimulated cytokine release. Stimulation of IL-6 by SP occurred in a conventional receptor-mediated manner as demonstrated by its differential release by fragments SP 4-11 and SP 1-4 and by the blockage of IL-6 release with the non-peptide, NK-1 receptor antagonist, CP-99 994. In addition to the direct stimulation of inflammatory cytokines, SP (0.5 microM), in combination with TNFalpha (25 units/ml), synergistically stimulated IL-6 release. BEAS-2B cells also responded to the botanical irritant, capsaicin (10 microM) with increases in [Ca(2+)](i) and IL-8 cytokine release after 4 h exposure. The IL-8 release was dependent on the presence of extracellular calcium. Capsaicin-stimulated increases of [Ca(2+)](i) and cytokine release could be reduced to control levels by pre-exposure to capsazepine, an antagonist of capsaicin (i.e. vanilloid) receptor(s) or by deletion of extracellular calcium from the exposure media. The present data indicate that the BEAS-2B human epithelial cell line expresses neuropeptide and capsaicin-sensitive pathways, whose activation results in immediate increases of [Ca(2+)](i) stimulation of inflammatory cytokine transcripts and the release of their cytokine proteins.

Bridging the gap between in vitro and in vivo models for neurotoxicology

In vitro systems are widely used for investigation of neurotoxicant-induced perturbations of cellular functions. A variety of systems exist that demonstrate certain similarities to neurotoxicant-induced events in the intact animal are discussed, including single-cell types, systems that consider endpoints relevant in toxicology, and systems that consider heterogeneous cell interactions. Relationships between the in vitro and in vivo systems are examined in which ethanol, lead, polychlorinated biphenyl compounds, and organophosphate insecticides are examples. Situations in which the in vitro systems have been used to advantage are provided, along with cautions associated with their use.

Particulate matter initiates inflammatory cytokine release by activation of capsaicin and acid receptors in a human bronchial epithelial cell line

Recent experiments have shown that human bronchial epithelial cells (i.e., BEAS-2B) release pro-inflammatory cytokines (i.e., IL-6 and TNFalpha) in a receptor-mediated fashion in response to the neuropeptides, substance P (SP), calcitonin gene-related protein (CGRP), and the prototype botanical irritant capsaicin. In the present experiments, we examined the relevance of these receptors to particulate matter (PM)-associated cellular inflammation. BEAS-2B cells, exposed to residual oil fly ash particles (ROFA), responded with an immediate (<30 s) increase in intracellular calcium levels ([Ca2+]i), increases of key inflammatory cytokine transcripts (i.e., IL-6, IL-8, TNFalpha) within 2 h exposure, and subsequent release of IL-6 and IL-8 cytokine protein after 4 h exposure. Pretreatment of BEAS-2B cells with pharmacological antagonists selective for the SP or CGRP receptors reduced the ROFA-stimulated IL-6 cytokine production by approximately 25 and 50%, respectively. However, pretreatment of these cells with capsazepine (CPZ), an antagonist for capsaicin (i.e., vanilloid) receptors, inhibited the immediate increases in [Ca2+]i, diminished transcript (i.e., IL-6, IL-8, TNFalpha) levels and reduced IL-6 cytokine release to control levels. BEAS-2B cells exposed to ROFA in calcium-free media failed to demonstrate increases of [Ca2+]i and showed reduced levels of cytokine transcript (i.e., IL-6, IL-8, TNFalpha) and IL-6 release, suggesting that ROFA-stimulated cytokine formation was partially dependent on extracellular calcium sources. A final set of experiments compared the inflammatory properties of the soluble and acidic insoluble components of ROFA. BEAS-2B cells, exposed to ROFA or ROFA that had been filtered through a 0.2-micrometer pore filter, produced equivocal IL-6. BEAS-2B cells exposed to pH 5.0 media for 15 min released moderate amounts of IL-6, 4 h later. This cytokine release could be blocked by amiloride, a pH receptor antagonist, but not by CPZ. BEAS-2B cells, pretreated with amiloride before ROFA exposure, showed a partial (approximately 25%) reduction of IL-6. Together, these data indicate that the acidic, soluble components of ROFA initiate cytokine release in BEAS-2B cells through activation of both capsaicin- and pH-sensitive irritant receptors.

Differential effects of physostigmine and organophosphates on nicotinic receptors in neuronal cells of different species

The effects of the carbamate physostigmine and of the organophosphates (OPs) parathion, paraoxon and phenyl saligenin cyclic phosphate (PSP) were examined on different subtypes of neuronal nicotinic acetylcholine receptors (nAChR). Stimulation with 1 mM ACh induced transient nicotinic inward currents in mouse N1E-115 and human SH-SY5Y neuroblastoma and in locust thoracic ganglion cells. All four acetylcholinesterase (AChE) inhibitors reduced the nicotinic currents in a concentration-dependent manner. Parathion is about 50 times more potent in blocking nAChR, compared to its active AChE inhibiting metabolite paraoxon. The relative blocking potency of the different AChE inhibitors was the same in all cell types, and followed the order parathion > physostigmine > PSP > paraoxon. In N1E-115 cells the IC50 values of block amounted to 2 microM, 30 microM, 39 microM and 96 microM for parathion, physostigmine, PSP and paraoxon, respectively. In all cell types, the nicotinic currents were equally blocked by parathion. Human nAChR in SH-SY5Y cells appeared more sensitive to block by physostigmine, PSP and paraoxon, while these AChE inhibitors similarly inhibited nicotinic currents in insect cells and in mouse neuroblastoma cells. The observation that the concentration-dependence of block is different from that of AChE inhibition, indicates a distinct interaction of AChE inhibitors with nAChR. Only in locust cells physostigmine induced a non-desensitizing inward current, that appeared to originate from nAChR activation. Occasionally, the OPs were able to activate slow ionic currents in mouse, but not in human and locust cells. As the OP-induced agonistic activity in mouse cells was not associated with the blocking action, the target site appeared to be distinct from nAChR. These results show that AChE inhibitors block nAChR with different potencies, dependent on the compound and the receptor subtype, and may activate distinct ion currents in neuronal cells of different species origin.

Physostigmine and acetylcholine differentially activate nicotinic receptor subpopulations in Locusta migratoria neurons

The effects of acetylcholine (ACh) and physostigmine (PHY) on thoracic ganglion neurons of Locusta migratoria were investigated using whole-cell and cell-attached voltage clamp. ACh activated whole-cell currents with variable amplitudes, time course and ion channel block between cells, suggesting differential expression of nicotinic acetylcholine receptor (nAChR) subtypes. This was supported by selective block of the peak of the currents by the alpha7-specific alpha-conotoxin ImI. PHY at 100 microM evoked smaller whole-cell currents with variable amplitudes and marginal desensitization. The PHY/ACh amplitude ratio varied between cells, and was positively related to the time constant of decay of the ACh response. EC50 values for the peak amplitude of the ACh- and PHY-induced currents were 50 microM and 3 microM, respectively. Both agonists activated nAChR, indicated by equal voltage-dependence and reversal potentials and the same pharmacological properties of ACh and PHY responses. In addition, PHY and ACh induced ion channel block. Co-application and cross-desensitization experiments showed that ACh and PHY activate the same nAChR subpopulations. Both agonists activated nicotinic single channels with three conductance levels, which were equal for ACh and PHY, indicating activation of the same nAChR subtypes by both agonists. However, for all levels PHY displayed a lower open probability than ACh. Taken together, different whole-cell responses appear to originate from differential activation, desensitization and ion channel block by ACh and PHY of distinct nAChR populations.

Cellular aspects of persistent neurotoxicants: effects of Pb2+ on neuronal nicotinic acetylcholine receptors

Among persistent neurotoxicants inorganic lead (Pb2+) is known to cause a variety of cellular effects associated with alterations in neuronal performance. Here we describe differential effects of Pb2+ on distinct subtypes of neuronal nicotinic acetylcholine receptors (nAChR) in Xenopus oocytes expressing various combinations of alpha and beta receptor subunits. Transient inward currents evoked by ACh in voltage clamped oocytes expressing alpha4beta2 and alpha3beta4 nAChR are inhibited by external Pb2+ at concentrations in the range of 1 nM-200 microM. The sensitivities of oocytes expressing alpha4beta2 and alpha3beta4 nAChR vary greatly. Additional experiments suggest that this variation may be due to receptor heterogeneity, which is demonstrated for alpha4beta2 nAChR in cell-attached patch clamp experiments. Conversely, the inward current evoked by ACh in oocytes expressing alpha3beta2 nAChR is potentiated by Pb2+ at concentrations in the range of 1-250 microM. The potentiating effect shows little variation between oocytes and is similar for inward currents evoked by low and high concentrations of ACh. The distinct effects on alpha3beta2 nAChR as compared to alpha4beta2 and alpha3beta4 nAChR suggest that Pb2+ interacts with both alpha and beta subunits of the neuronal nAChR. The effects of Pb2+ on defined subtypes of nAChR in oocytes are compared to those on ligand-gated ion channels in intact cells.

In vitro approaches to species and receptor diversity in cellular neurotoxicology

Effects of selective and non-selective neurotoxic compounds on membrane currents mediated by nicotinic acetylcholine receptors (nAChR), natively expressed in cultured cells and artificially expressed in Xenopus oocytes, have been investigated in vitro using voltage clamp techniques. Mammalian neuronal nAChR in cultured mouse N1E-115 cells, muscle type nAChR in cultured mouse BC3H1 cells and insect neuronal nAChR in dissociated locust thoracic ganglion neurons show interspecies differences in sensitivity to neurotoxic compounds. The nitromethylene heterocyclic insecticide WL145004 and physostigmine selectively agonize the insect type nAChR. The mouse neuronal and muscle types of nAChR are much less sensitive to and are partially inhibited by WL 145004. Intraspecies differences have been investigated for the effects of Pb(2+) on subtypes of nAChR expressed in Xenopus oocytes. The nature of the effect of the heavy metal Pb(2+) depends on the combination of mammalian neuronal a and beta nAChR subunits. Ion currents mediated by alpha4beta2 and alpha3beta4 nAChR are inhibited and those mediated by alpha3beta2 nAChR are potentiated by Pb(2+). Distinct sensitivities of subtypes of mammalian neuronal nAChR to agonists and antagonists are employed to characterize native nAChR in N 1E-115 cells. Implications of receptor diversity for neurotoxicology are discussed.

Differential muscarinic receptor binding of acetylcholinesterase inhibitors in rat brain, human brain and Chinese hamster ovary cells expressing human receptors

Displacement of muscarinic radioligands by the cholinesterase inhibitors parathion, paraoxon, physostigmine and phenyl saligenin cyclic phosphate was examined in rat cortex and brain stem, human cortex and brain stem, and in Chinese hamster ovary (CHO) cells expressing human M2 or M4 muscarinic acetylcholine receptors. None of the cholinesterase inhibitors tested significantly affected binding of the antagonist [3H]quinuclinidyl benzilate. However, the agonist [3H]oxotremorine-methiodide (3H]oxo-M) was displaced by all compounds tested in a differential manner. Parathion only marginally displaced [H]oxo-M binding with pKi values < 5 in all tissue or cell types. In rat brain paraoxon, physostigmine and phenyl saligenin cyclic phosphate displaced [3H]oxo-M with pKi values of 7.5, 7.0 and 6.1, respectively. The cholinesterase inhibitors displaced [3H]oxo-M in human brain at 15- to 250-fold higher concentrations, that is with pKi values of 6.3, 4.6 and 4.2, respectively. Maximal displacement of [3H]oxo-M varied between 25% and 95%, depending on the species and the compound. Human receptors in brain and in CHO cells were equally sensitive to displacement of [3H]oxo-M by parathion, physostigmine and phenyl saligenin cyclic phosphate. However, paraoxon displaced [3H]oxo-M at > or = 35-fold lower concentrations from human receptors in brain than in CHO cells. In conclusion, the data show that cholinesterase inhibitors interfere with agonist binding to muscarinic acetylcholine receptors. The species-selectivity of the displacement appears to result from differences between rat and human muscarinic acetylcholine receptors. In addition, for paraoxon marked differences exist between the sensitivity of human muscarinic acetylcholine receptors in brain tissue and of those expressed in clonal CHO cells.

Dual, non-competitive interaction of lead with neuronal nicotinic acetylcholine receptors in N1E-115 neuroblastoma cells

In cultured mouse neuroblastoma N1E-115 cells, inorganic lead (Pb2+) affects inward currents induced by activation of neuronal type nicotinic acetylcholine receptors (nAChR) in a biphasic manner. At nanomolar concentrations a blocking action is observed, while at submillimolar concentrations this blocking effect is reversed, resulting in a U-shaped concentration-effect curve. Maximal block by 90% is observed at 1-3 microM Pb2+. The interactions of Pb2+ with nAChR were examined at the blocking concentration of 10 nM Pb2+ and at 10 microM Pb2+, presenting the reversal of block. The fitted Emax for nAChR receptor activation by ACh was attenuated at both high and low Pb2+ concentrations by 24% and 54%, respectively. The EC50 values of the activation curves were not significantly altered; amounting to 53 microM, 64 microM and 86 microM ACh in the control situation and in the presence of 10 nM and 10 microM Pb2+, respectively. Further, receptor desensitization and ion channel block by ACh were also not affected by Pb2+. The results indicate that Pb2+ affects nAChR in a dual manner that involves inhibition and potentiation, both by non-competitive interactions. Neuronal nAChR expressed in N1E-115 cells resemble a combination of alpha 4 and beta 2 subunits, that constitute the predominant subunits in the central nervous system. The differential inhibition and potentiation of nAChR, together with the high sensitivity, are of interest with respect to Pb2+ neurotoxicity.

Cell culture models of interspecies selectivity to organophosphorous insecticides

In toxicology, the need to reduce uncertainties in human risk assessment is met by understanding why species and individuals within that species respond differently to chemical exposure. This kind of information is needed when extrapolating data from experimental (i.e., whole animal) systems to the human condition in terms of risk assessment. In 1993 the Neurotoxicology Division of the Environmental Protection Agency funded several investigators to examine this phenomenon (i.e., interspecies selectivity) using cell culture models. Organophosphorous (OP) insecticides were examined since they are characterized by an extremely divergent interspecies response. In 1995, a symposium entitled Novel Insights into Chemical Neurotoxicity, sponsored by the Society for In Vitro Biology featured this research. In it, a historical overview of the phenomenon of interspecies selectivity to OP insecticides was given, current explanations for it were discussed and contemporary in vitro models being used to explain it, were described. Data from these studies have helped to redefine the underlying mechanisms that characterize and influence the cross-species response to insecticides. These experiments have refocused the explanation of this phenomenon to include cellular metabolism, target enzyme baseline activities, and receptor-mediated electrophysiological and second-messenger events. Several investigators on this panel also reported on the use of subcellular markers (e.g., target esterases, second messengers, ionic fluxes) to differentiate neuropathy-causing OP compounds from acetylcholinesterase inhibitors. After these presentations, technical considerations used in the designed of in vitro neurotoxicity studies were discussed.

Time-dependent differential changes of immune function in rats exposed to chronic intermittent noise

Noise is a highly relevant environmental and clinical stressor. Compared to most other experimental stressors, noise is a modest activator of neuroendocrine pathways that mimic the situation in human health where neuroendocrine activation by environmental stressors is often absent or difficult to establish. Little is known about the effects of noise exposure on the immune system. In the present work, the effects of a low-intensity chronic intermittent unpredictable noise regimen on various parameters of immune function was studied. Male wistar rats were exposed to a randomized noise protocol (white noise, 85 dB, 2-20 kHz) for 10 h per day, 15 min per h over a total period of 3 weeks. Control animals were exposed to ambient sound only. Immune function was monitored after 24 h, 7 days, and 21 days of noise exposure. Noise induced several significant changes in immune function in a time-dependent differential pattern involving both immunosuppression and immunoenhancement. After 24 h, serum IgM levels were increased and peripheral phagocytic activity was decreased. Splenic lymphocytic proliferation to mitogens was significantly decreased after 7 days, but slightly elevated after 3 weeks. The activity of splenic NK cells was increased significantly after 24 h and 7 days, but suppressed after 3 weeks. These results show that various parameters of immune function are affected differentially over time in a period of chronic mild noise stress, possibly due to sequential activation of different physiological mechanisms.

Noise stress and airway toxicity: a prospect for experimental analysis

People are exposed to a mixture of chemicals, noise, bad smells and other factors. Little is known about the possible interactions between these various contaminants. Although research on the effects of chemical mixtures has been initiated, the combination of chemical and non-chemical factors has received little attention. This paper summarizes the possible effects of combined exposure to noise and the air pollutant ozone, which are both factors with a high prevalence in the Western society. A series of animal experiments are presented to evaluate the possible combined effects of noise and air pollution.

Differential effects of organotin compounds on voltage-gated potassium currents in lymphocytes and neuroblastoma cells

Effects of organotin compounds were studied on voltage-gated K+ current in whole-cell voltage clamped lymphocytes and in N1E-115 neuroblastoma cells. In human peripheral blood lymphocytes the immunotoxic compounds dibutyltinchloride (DBT, 2.5 microM) and triphenyltinchloride (TPhT, 2.5 microM) decrease the peak amplitude of the K+ current and prolong time to peak. Tributyltinchloride (TBT, 2.5 microM) decreases the K+ current to a greater extent than DBT and TPhT, without affecting the time to peak. The neurotoxic organotin compound trimethyltinchloride (TMT, 2.5 microM) does not affect the voltage-gated K+ current in lymphocytes. Similar effects of DBT were observed in freshly isolated and PHA-activated human lymphocytes and with rat thymocytes. On the other hand, in mouse N1E-115 neuroblastoma cells, none of the organotin compounds altered the voltage-dependent K+ current. In human lymphocytes DBT affects both the peak amplitude and the time to peak of the K+ current in a concentration-dependent manner. At the maximum concentration of 10 microM tested, the peak amplitude of the K+ current was reduced to 22 +/- 4% of the control current. The IC50 and slope factor for block of the peak outward current by DBT amounts to 6.7 +/- 0.4 microM, and 2.7 +/- 0.4, respectively. The delay in K+ current activation does not saturate. At 10 microM DMT increases the time to peak to 332 +/- 12% of the control value. The present results suggest that the effects by DBT originate from two separate interactions with the voltage-gated K+ channel at the extracellular site of the membrane: a direct effect on the closed K+ channel causing a delay in current activation and a membrane-related effect causing inhibition of the K+ current. The differential effects of the organotin compounds may relate to their differential toxicological action.

Potentiation and inhibition of subtypes of neuronal nicotinic acetylcholine receptors by Pb2+

Effects of inorganic lead (Pb2+) on defined subtypes of neuronal nicotinic acetylcholine receptors have been investigated. Voltage clamp experiments have been performed on Xenopus oocytes expressing alpha 3 beta 2, alpha 3 beta 4 and alpha 4 beta 2 neuronal nicotinic acetylcholine receptor subunit combinations. In oocytes expressing the alpha 3 beta 2 subunit combination Pb2+ enhances the peak amplitude of nicotinic acetylcholine receptor-mediated inward currents evoked by superfusion with 100 microM acetylcholine. At concentrations of 1-250 microM, Pb2+ potentiates alpha 3 beta 2 receptor-mediated inward current concentration dependently by a factor of 1.1-11.0. Inward currents evoked by low (3 microM) and high (1 mM) concentrations of acetylcholine are potentiated to a similar extent. Conversely, in oocytes expressing the alpha 3 beta 4 subunit combination Pb2+ inhibits the nicotinic receptor-mediated inward currents evoked with 100 microM acetylcholine. Inhibitory effects are observed in the concentration range of 1 nM-100 microM Pb2+ but the degree of inhibition varies between oocytes. A similar inhibition of the alpha 4 beta 2 nicotinic receptor-mediated inward current by Pb2+ indicates that alpha as well as beta subunits are involved in the potentiating and inhibitory effects. Possible reasons for the variation in the inhibitory effects of Pb2+ on alpha 3 beta 4 and alpha 4 beta 2 nicotinic receptor-mediated inward currents have been investigated and are discussed. The divalent cations Ca2+ and Mg2+ potentiate both alpha 3 beta 2 and alpha 3 beta 4 nicotinic receptor-mediated inward currents. The distinct modulation of receptor function by Pb2+ and by Ca2+ and Mg2+ and the dependence of the modulatory effect of Pb2+ on subunit composition suggest that Pb2+ interacts with multiple sites on the alpha and beta subunits of neuronal nicotinic acetylcholine receptors.

Native nicotinic acetylcholine receptors in human Imr32 neuroblastoma cells: functional, immunological and pharmacological properties

IMR32 cells express two classes of surface nicotinic receptors: those labelled with high affinity by [125I]neuronal toxin, and those labelled by [125I]alpha-bungarotoxin. Whole-cell patch-clamp recordings indicate that both classes of receptor are able to elicit inward currents that are totally blocked by d-tubocurarine but only partially blocked by alpha-bungarotoxin. In IMR32 cells, nicotine induces an increase in the intracellular level of free Ca2+. This increase, which is also completely blocked by d-tubocurarine and only partially blocked by alpha-bungarotoxin and Cd2+, is due to extracellular calcium influx through both the nicotinic receptors and the voltage-activated Ca2+ channels. By using subunit-specific polyclonal antibodies, we have demonstrated that the alpha-bungarotoxin receptors contain the alpha 7 subunit, but none of the other subunits whose transcripts are present in IMR32 cells. The pharmacological profile of these human alpha 7-containing alpha-bungarotoxin receptors is similar to that observed in the native chick alpha 7 receptor, but there are also some species-specific differences.

Voltage-gated and Ca(2+)-activated K+ channels in intact human T lymphocytes. Noninvasive measurements of membrane currents, membrane potential, and intracellular calcium

Voltage-gated n-type K(V) and Ca(2+)-activated K+ [K(Ca)] channels were studied in cell-attached patches of activated human T lymphocytes. The single-channel conductance of the K(V) channel near the resting membrane potential (Vm) was 10 pS with low K+ solution in the pipette, and 33 pS with high K+ solution in the pipette. With high K+ pipette solution, the channel showed inward rectification at positive potentials. K(V) channels in cell-attached patches of T lymphocytes inactivated more slowly than K(V) channels in the whole-cell configuration. In intact cells, steady state inactivation at the resting membrane potential was incomplete, and the threshold for activation was close to Vm. This indicates that the K(V) channel is active in the physiological Vm range. An accurate, quantitative measure for Vm was obtained from the reversal potential of the K(V) current evoked by ramp stimulation in cell-attached patches, with high K+ solution in the pipette. This method yielded an average resting Vm for activated human T lymphocytes of -59 mV. Fluctuations in Vm were detected from changes in the reversal potential. Ionomycin activates K(Ca) channels and hyperpolarizes Vm to the Nernst potential for K+. Elevating intracellular Ca2+ concentration ([Ca2+]i) by ionomycin opened a 33-50-pS channel, identified kinetically as the CTX-sensitive IK-type K(Ca) channel. The Ca2+ sensitivity of the K(Ca) channel in intact cells was determined by measuring [Ca2+]i and the activity of single K(Ca) channels simultaneously. The threshold for activation was between 100 and 200 nM; half-maximal activation occurred at 450 nM. At concentrations > 1 microM, channel activity decreased. Stimulation of the T-cell receptor/CD3 complex using the mitogenic lectin, PHA, increased [Ca2+]i, and increased channel activity and current amplitude resulting from membrane hyperpolarization.

Subunit-dependent action of lead on neuronal nicotinic acetylcholine receptors expressed in Xenopus oocytes

1. Pb2+ affects neuronal nicotinic acetylcholine receptors (nAChR) in N1E-115 neuroblastoma cells in a dual manner. At nanomolar concentrations a blockade is observed, while at submillimolar concentrations this blocking effect is reversed. 2. The Xenopus oocyte expression system was used to examine whether the dual effect of Pb2+ is related to a differential action on nAChR subtypes. Effects of Pb2+ were investigated in oocytes expressing nAChR after co-injection of alpha 3 and beta 2 or alpha 3 and beta 4 cDNA. 3. At 1-250 mumol/L, Pb2+ causes a 10-1000% increase of the response mediated by the alpha 3 beta 2 nAChR. 4. Pb2+ blocks ACh-induced inward currents mediated by alpha 3 beta 4 nAChR. The inhibitory potency of Pb2+ greatly varies between cells. In 50% of the cells concentrations < or = 1 mumol/L Pb2+ blocked the nicotinic response by 31-93%. In the other cells even at higher concentrations Pb2+ caused only 0-65% inhibition. 5. These results show that Pb2+ may both potentiate and block nAChR, depending on the type of nAChR subunit expressed.

Differential modulation of alpha 3 beta 2 and alpha 3 beta 4 neuronal nicotinic receptors expressed in Xenopus oocytes by flufenamic acid and niflumic acid

Effects of flufenamic acid (FFA) and niflumic acid (NFA), which are often used to block Ca(2+)-activated Cl- current, have been investigated in voltage-clamped Xenopus oocytes expressing alpha 3 beta 2 and alpha 3 beta 4 nicotinic ACh receptors (nAChRs). NFA and FFA inhibit alpha 3 beta 2 nAChR-mediated inward currents and potentiate alpha 3 beta 4 nAChR-mediated inward currents in normal, Cl(-)-free and Ca(2+)-free solutions to a similar extent. The concentration-dependence of the inhibition of alpha 3 beta 2 nAChR-mediated ion current yields IC50 values of 90 microM for FFA and of 260 microM for NFA. The potentiation of alpha 3 beta 4 nAChR-mediated ion current by NFA yields an EC50 value of 30 microM, whereas the effect of FFA does not saturate for concentrations of up to 1 mM. At 100 microM, FFA reduces the maximum of the concentration-effect curve of ACh for alpha 3 beta 2 nAChRs, but leaves the EC50 of ACh unaffected. The same concentration of FFA potentiates alpha 3 beta 4 nAChR-mediated ion currents for all ACh concentrations and causes a small shift of the concentration-effect curve of ACh to lower agonist concentrations. The potentiation, like the inhibition, is most likely due to a noncompetitive effect of FFA. Increasing ACh-induced inward current either by raising the agonist concentration from 10 microM to 200 microM or by coapplication of 10 microM ACh and 200 microM FFA causes a similar enhancement of block of the alpha 3 beta 4 nAChR-mediated ion current by Mg2+. This suggests that the effects of FFA and of an increased agonist concentration result in a similar functional modification of the alpha 3 beta 4 nAChR-operated ion channel. It is concluded that alpha 3 beta 4 and alpha 3 beta 2 nAChRs are oppositely modulated by FFA and NFA through a direct beta-subunit-dependent effect.

Species-specific Effects of Nitromethylene Heterocycle Insecticides on Nicotinic Receptors in Locust Neurons and Mouse N1E-115 and BC3H1 Cells

The effects of nitromethylene heterocycle (NMH) insecticides on subtypes of nicotinic acetylcholine (nACh) receptors were investigated in locust thoracic ganglion neurons, mouse N1E-115 neuroblastoma cells, and mouse BC3H1 muscle cells by using electrophysiological techniques. In locust neurons, all of the six NMH insecticides tested induced transient inward currents resembling nicotinic ACh-induced inward currents, while, in the continued presence of the NMH compounds, the ACh-induced inward current was blocked. The amplitude of the inward current and the blocking effects of the NMH insecticides were enhanced by concentrations between 0.1 and 10μM. Cross-desensitisation with the ACh-induced inward current confirmed that the NMH-induced inward current was governed by the activation of nACh receptors. Mammalian endplate type nACh receptors in BC3H1 cells and mammalian neuronal type nACh receptors in N1E-115 cells were much less sensitive to the NMH insecticides than the locust neuronal nACh receptors. At a concentration of 10μM, which blocked 80–100% of the ACh-induced inward current in locust neurons, NMH insecticides only partially blocked the ACh-induced inward currents mediated by the two subtypes of mammalian nACh receptors. NMH insecticides also failed to induce significant agonist effects in the mammalian cells at this concentration.

The results provide a possible explanation for the selectively greater toxicity of NMH insecticides to insects than to vertebrates, at the level of nACh receptor subtypes and, hence, demonstrate that this in vitro approach is valuable for the investigation of species-specific interactions of compounds at their target site.

Metal interactions with voltage- and receptor-activated ion channels

Effects of Pb and several other metal ions on various distinct types of voltage-, receptor- and Ca-activated ion channels have been investigated in cultured N1E-115 mouse neuroblastoma cells. Experiments were performed using the whole-cell voltage clamp and single-channel patch clamp techniques. External superfusion of nanomolar to submillimolar concentrations of Pb causes multiple effects on ion channels. Barium current through voltage-activated Ca channels is blocked by micromolar concentrations of Pb, whereas voltage-activated Na current appears insensitive. Neuronal type nicotinic acetylcholine receptor-activated ion current is blocked by nanomolar concentrations of Pb and this block is reversed at micromolar concentrations. Serotonin 5-HT3 receptor-activated ion current is much less sensitive to Pb. In addition, external superfusion with micromolar concentrations of Pb as well as of Cd and aluminum induces inward current, associated with the direct activation of nonselective cation channels by these metal ions. In excised inside-out membrane patches of neuroblastoma cells, micromolar concentrations of Ca activate small (SK) and big (BK) Ca-activated K channels. Internally applied Pb activates SK and BK channels more potently than Ca, whereas Cd is approximately equipotent to Pb with respect to SK channel activation, but fails to activate BK channels. The results show that metal ions cause distinct, selective effects on the various types of ion channels and that metal ion interaction sites of ion channels may be highly selective for particular metal ions.

alpha 4 beta 2 subunit combination specific pharmacology of neuronal nicotinic acetylcholine receptors in N1E-115 neuroblastoma cells

Pharmacological characteristics of native neuronal nicotinic acetylcholine receptor-mediated ion currents in mouse N1E-115 neuroblastoma cells have been investigated by superfusion of voltage clamped cells with known concentrations of the agonists acetylcholine, nicotine and cytisine, and the antagonists alpha-bungarotoxin and neuronal bungarotoxin. The sensitivity of the nicotinic acetylcholine receptor for agonists followed the agonist potency rank-order: nicotine approximately acetylcholine >> cytisine. The EC50 values of acetylcholine and nicotine are 78 microM and 76 microM, respectively. Equal concentrations of acetylcholine and nicotine induce inward currents with approximately the same peak amplitude whereas cytisine induces much smaller inward currents. Acetylcholine-induced currents are unaffected by high concentrations of alpha-bungarotoxin. Conversely, at 10 and 90 nM neuronal bungarotoxin reduces the amplitude of the 1 mM acetylcholine-induced inward current to 47% and 11% of control values, respectively. Both the agonist potency rank-order and the differential sensitivity to snake toxins of nicotinic receptors in N1E-115 cells are consistent with the known pharmacological profile of alpha 4 beta 2 nicotinic receptors expressed in Xenopus oocytes and distinct from those of all other nicotinic acetylcholine receptors of known functional subunit compositions. All data indicate that the native nicotinic acetylcholine receptor in N1E-115 cells is an assembly of alpha 4 and beta 2 subunits, the putative major subtype of nicotinic acetylcholine receptor in the brain.

Characterization of Ca(2+)-activated K+ channels in excised patches of human T lymphocytes

Ca(2+)-activated K+ [K(Ca)] channels were studied in excised patches of resting and activated human peripheral blood T lymphocytes. The K(Ca) channel had a single-channel conductance of 50 +/- 6 pS in symmetrical high-K+ solutions in the potential range of -100 to -10 mV and was inwardly rectifying at more depolarized potentials. The channel was sensitive to block by charybdotoxin (10 nM) and insensitive to apamin (3 nM). Half-maximum activation occurred at an internal free Ca2+ concentration of 360 +/- 110 nM. The concentration-effect curve had a slope factor of 0.83 +/- 0.12, suggesting a 1:1 interaction of Ca2+ ions with the channel. Ca2+ affects the open time probability of the K(Ca) channels, mainly by modulating the frequency of channel opening. The open probability did not show voltage dependence. The kinetics of the channel could be described assuming one open state and two closed states. The time constant of the exponential describing the open time distribution amounted to 2.8 +/- 1.2 ms, whereas the closed time distribution could be described with two exponentials with time constants of 0.2 +/- 0.05 ms and 8.0 +/- 2.1 ms, respectively. Resting T lymphocytes expressed a low number of channels but the density of channels increased dramatically during chronic phytohaemagglutinin stimulation.

Veratridine blocks voltage-gated potassium current in human T lymphocytes and in mouse neuroblastoma cells

(i) Effects of veratridine on ionic conductances of human peripheral blood T lymphocytes have been investigated using the whole-cell patch-clamp technique. (ii) Veratridine reduces the net outward current evoked by membrane depolarizations. The reduction originates from block of a 4-aminopyridine-sensitive, voltage-gated K+ current. (iii) Human T lymphocytes do not appear to express voltage-gated Na+ channels, since inward currents are observed neither in control nor in veratridine- and bretylium-exposed lymphocytes. (iv) The effect of veratridine consists of an increase in the rate of decay of the voltage-gated K+ current and a reduction of the peak current amplitude. Both effects depend on veratridine concentration. Half-maximum block occurs at 97 microM and the time constant of decay is reduced by 50% at 54 microM of veratridine. (v) Possible mechanisms of veratridine action are discussed. The increased rate of K+ current decay is most likely due to open channel block. The decrease of current amplitude may involve an additional mechanism. (vi) In cultured mouse neuroblastoma N1E-115 cells, veratridine blocks a component of voltage-gated K+ current, in addition to its effect on voltage-gated Na+ current. This result shows that the novel effect of veratridine is not confined to lymphocytes.