Efficacy and safety of ixekizumab treatment for Japanese patients with moderate to severe plaque psoriasis, erythrodermic psoriasis and generalized pustular psoriasis: Results from a 52-week, open-label, phase 3 study (UNCOVER-J).

Psoriasis, a chronic, immune-mediated skin disease characterized by red, scaly plaques, affects approximately 0.3% of the population in Japan. The aim of this open-label study was to evaluate the long-term efficacy and safety of ixekizumab, a humanized, anti-interleukin-17A monoclonal antibody, in Japanese patients with plaque psoriasis (n = 78, including 11 psoriatic arthritis), erythrodermic psoriasis (n = 8) and generalized pustular psoriasis (n = 5). Ixekizumab was administrated s.c. at baseline (week 0, 160 mg), from weeks 2 to 12 (80 mg every 2 weeks), and from weeks 16 to 52 (80 mg every 4 weeks). At week 52, 92.3% of patients with plaque psoriasis achieved Psoriasis Area and Severity Index (PASI) 75, 80.8% achieved PASI 90, 48.7% achieved PASI 100, and 52.6% had remission of plaques (by static Physician Global Assessment, sPGA [0]). Difficult to treat areas of psoriasis (nail or scalp) also responded to ixekizumab. All patients with psoriatic arthritis who were assessed (5/5) achieved an American College of Rheumatology 20 response. Most patients with erythrodermic psoriasis or generalized pustular psoriasis responded to ixekizumab and the clinical outcome was maintained over 52 weeks (75% and 60% of patients achieved sPGA [0, 1] at week 52, respectively). Mostly mild or moderate treatment-emergent adverse events were reported by 79 of 91 patients; the most common were nasopharyngitis, eczema, seborrheic dermatitis, urticaria and injection site reactions. In conclusion, 52-week ixekizumab treatment was efficacious and well tolerated in Japanese patients with plaque psoriasis. Efficacy was also observed in patients with erythrodermic psoriasis, generalized pustular psoriasis and psoriatic arthritis.

Efficacy and Safety of Baricitinib in Japanese Patients with Active Rheumatoid Arthritis Receiving Background Methotrexate Therapy: A 12-week, Double-blind, Randomized Placebo-controlled Study.

OBJECTIVE: To evaluate efficacy and safety, baricitinib [Janus kinase (JAK) 1/JAK2 inhibitor] was compared with placebo in Japanese patients with active rheumatoid arthritis (RA) despite background treatment with methotrexate (MTX). METHODS: This was a phase IIB, double-blind, randomized, placebo-controlled study (clinicaltrials.gov: NCT01469013). Patients had moderate to severe active adult-onset RA despite stable treatment with MTX. Patients (n = 145) were randomized in a 2:1:1:1:1 ratio to placebo or 1 mg, 2 mg, 4 mg, or 8 mg oral baricitinib daily for 12 weeks. The primary analysis compared the combined 4/8-mg dose groups with placebo for the American College of Rheumatology (ACR) 20 response rate at 12 weeks. Other outcomes included additional measures of disease activity, physical function, laboratory abnormalities, and adverse events. RESULTS: A significantly higher proportion of patients in the combined 4/8-mg baricitinib group (37/48, 77%) compared with the placebo group (15/49, 31%) had at least an ACR20 response after 12 weeks of treatment (p < 0.001). Significant improvements in disease activity, remission, and physical function were observed as early as Week 2 of treatment with baricitinib, particularly with daily doses of ≥ 4 mg. Only 1 patient receiving baricitinib discontinued because of an adverse event. Adverse event rates with baricitinib doses ≤ 4 mg daily were similar to placebo, but there was a higher incidence of adverse events and laboratory abnormalities in the 8-mg group. CONCLUSION: In this phase II study, baricitinib was well tolerated and rapidly improved the signs, symptoms, and physical function of Japanese patients with active RA, supporting continued development of baricitinib (clinicaltrials.gov NCT01469013).

Role of syntaxin 18 in the organization of endoplasmic reticulum subdomains.

The presence of subdomains in the endoplasmic reticulum (ER) enables this organelle to perform a variety of functions, yet the mechanisms underlying their organization are poorly understood. In the present study, we show that syntaxin 18, a SNAP (soluble NSF attachment protein) receptor localized in the ER, is important for the organization of two ER subdomains, smooth/rough ER membranes and ER exit sites. Knockdown of syntaxin 18 caused a global change in ER membrane architecture, leading to the segregation of the smooth and rough ER. Furthermore, the organization of ER exit sites was markedly changed concomitantly with dispersion of the ER-Golgi intermediate compartment and the Golgi complex. These morphological changes in the ER were substantially recovered by treatment of syntaxin-18-depleted cells with brefeldin A, a reagent that stimulates retrograde membrane flow to the ER. These results suggest that syntaxin 18 has an important role in ER subdomain organization by mediating the fusion of retrograde membrane carriers with the ER membrane.

Identification of the neuroblastoma-amplified gene product as a component of the syntaxin 18 complex implicated in Golgi-to-endoplasmic reticulum retrograde transport.

Syntaxin 18, a soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein receptor (SNARE) protein implicated in endoplasmic reticulum (ER) membrane fusion, forms a complex with other SNAREs (BNIP1, p31, and Sec22b) and several peripheral membrane components (Sly1, ZW10, and RINT-1). In the present study, we showed that a peripheral membrane protein encoded by the neuroblastoma-amplified gene (NAG) is a subunit of the syntaxin 18 complex. NAG encodes a protein of 2371 amino acids, which exhibits weak similarity to yeast Dsl3p/Sec39p, an 82-kDa component of the complex containing the yeast syntaxin 18 orthologue Ufe1p. Under conditions favoring SNARE complex disassembly, NAG was released from syntaxin 18 but remained in a p31-ZW10-RINT-1 subcomplex. Binding studies showed that the extreme N-terminal region of p31 is responsible for the interaction with NAG and that the N- and the C-terminal regions of NAG interact with p31 and ZW10-RINT-1, respectively. Knockdown of NAG resulted in a reduction in the expression of p31, confirming their intimate relationship. NAG depletion did not substantially affect Golgi morphology and protein export from the ER, but it caused redistribution of Golgi recycling proteins accompanied by a defect in protein glycosylation. These results together suggest that NAG links between p31 and ZW10-RINT-1 and is involved in Golgi-to-ER transport.

p31 deficiency influences endoplasmic reticulum tubular morphology and cell survival.

p31, the mammalian orthologue of yeast Use1p, is an endoplasmic reticulum (ER)-localized soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP) receptor (SNARE) that forms a complex with other SNAREs, particularly syntaxin 18. However, the role of p31 in ER function remains unknown. To determine the role of p31 in vivo, we generated p31 conditional knockout mice. We found that homozygous deletion of the p31 gene led to early embryonic lethality before embryonic day 8.5. Conditional knockout of p31 in brains and mouse embryonic fibroblasts (MEFs) caused massive apoptosis accompanied by upregulation of ER stress-associated genes. Microscopic analysis showed vesiculation and subsequent enlargement of the ER membrane in p31-deficient cells. This type of drastic disorganization in the ER tubules has not been demonstrated to date. This marked change in ER structure preceded nuclear translocation of the ER stress-related transcription factor C/EBP homologous protein (CHOP), suggesting that ER stress-induced apoptosis resulted from disruption of the ER membrane structure. Taken together, these results suggest that p31 is an essential molecule involved in the maintenance of ER morphology and that its deficiency leads to ER stress-induced apoptosis.

N-terminal region of ZW10 serves not only as a determinant for localization but also as a link with dynein function.

ZW10 interacts with dynamitin, a subunit of the dynein accessory complex dynactin, and functions in termination of the spindle checkpoint during mitosis and in membrane transport between the endoplasmic reticulum (ER) and Golgi apparatus during interphase. Its associations with kinetochores and ER membranes are mediated by Zwint-1 and RINT-1, respectively. A previous yeast two-hybrid study showed that the C-terminal region of ZW10 interacts with dynamitin, and part of this region has been used as an inhibitor of ZW10 function. In the present study, we reinvestigated the interaction between ZW10 and dynamitin, and showed that the N-terminal region of ZW10 is the major binding site for dynamitin and, like full-length ZW10, could potentially move along microtubules to the centrosomal area in a dynein-dynactin-dependent manner. Competitive binding experiments demonstrated that dynamitin and RINT-1 occupy the same N-terminal region of ZW10 in a mutually exclusive fashion. Consistent with this, over-expression of RINT-1 interfered with the dynein-dynactin-mediated movement of ZW10 to the centrosomal area. Given that the N-terminal region of ZW10 also interacts with Zwint-1, this region may be important for switching partners; one partner is a determinant for localization (kinetochore and ER) and the other links ZW10 to dynein function.

Sec22b-dependent assembly of endoplasmic reticulum Q-SNARE proteins.

SNARE (soluble N-ethylmaleimide-sensitive fusion protein-attachment protein receptor) proteins involved in membrane fusion usually contain a conserved alpha-helix (SNARE motif) that is flanked by a C-terminal transmembrane domain. They can be classified into Q-SNARE and R-SNARE based on the structural property of their motifs. Assembly of four SNARE motifs (Qa, b, c and R) is supposed to trigger membrane fusion. We have previously shown that ER (endoplasmic reticulum)-localized syntaxin 18 (Qa) forms a complex with BNIP1 (Qb), p31/Use1 (Qc), Sec22b (R) and several peripheral membrane proteins. In the present study, we examined the interaction of syntaxin 18 with other SNAREs using pulldown assays and CD spectroscopy. We found that the association of syntaxin 18 with Sec22b induces an increase in alpha-helicity of their SNARE motifs, which results in the formation of high-affinity binding sites for BNIP1 and p31. This R-SNARE-dependent Q-SNARE assembly is quite different from the assembly mechanisms of SNAREs localized in organelles other than the ER. The implication of the mechanism of ER SNARE assembly is discussed in the context of the physiological roles of the syntaxin 18 complex.