Role of Histidine 78 of leaf ferredoxin in the interaction with ferredoxin-NADP+ reductase: regulation of pH dependency and negative cooperativity with NADP(H).

In chloroplast stroma, dynamic pH change occurs in response to fluctuating light conditions. We investigated the pH-dependent electron transfer activity between ferredoxin-NADP+ reductase (FNR) and ferredoxin (Fd) isoproteins from maize leaves. By increasing pH (from 5.5 to 8.5), the electron transfer activity from FNR to photosynthetic-type Fd (Fd1) significantly increased while the activity to nonphotosynthetic type Fd (Fd3) decreased, which was mainly due to their differences in the pH dependency of Km for Fd. Mutation of His78 of Fd1 to Val, corresponding amino acid residue in Fd3, lost the pH dependency, indicating a regulatory role of the His78 in the interaction with FNR. We previously showed that the interaction between FNR and Fd was weakened by the allosteric binding of NADP(H) on FNR. His78Val Fd1 mutant largely suppressed this negative cooperativity. These results indicate the involvement of Fd1 His78 in pH dependency and negative cooperativity in the interaction with FNR.

Molecular mechanism of negative cooperativity of ferredoxin-NADP+ reductase by ferredoxin and NADP(H): involvement of a salt bridge between Asp60 of ferredoxin and Lys33 of FNR.

Ferredoxin-NADP+ reductase (FNR) in plants receives electrons from ferredoxin (Fd) and converts NADP+ to NADPH at the end of the photosynthetic electron transfer chain. We previously showed that the interaction between FNR and Fd was weakened by the allosteric binding of NADP(H) on FNR, which was considered as a part of negative cooperativity. In this study, we investigated the molecular mechanism of this phenomenon using maize FNR and Fd, as the three-dimensional structure of this Fd:FNR complex is available. NMR chemical shift perturbation analysis identified a site (Asp60) on Fd molecule which was selectively affected by NADP(H) binding on FNR. Asp60 of Fd forms a salt bridge with Lys33 of FNR in the complex. Site-specific mutants of FdD60 and FNRK33 suppressed the negative cooperativity (downregulation of the interaction between FNR and Fd by NADPH), indicating that a salt bridge between FdD60 and FNRK33 is involved in this negative cooperativity.

Predictive value of serum amyloid a levels for requirement of concomitant methotrexate in tocilizumab initiation: A post hoc analysis of the SURPRISE study.

Objectives: To identify predictive factors for remission by tocilizumab monotherapy in rheumatoid arthritis (RA) patients.Methods: This is a post hoc analysis of the SURPRISE study, a 2-year randomized, controlled study comparing the efficacy of tocilizumab with (ADD-ON) and without methotrexate (SWITCH). The primary endpoint was DAS28-ESR remission (<2.6) at week 24. The change in modified total Sharp score from baseline to week 52 (ΔmTSS/year) was also assessed as an endpoint. The effect of clinical parameters at baseline on remission was estimated by logistic regression analysis.Results: In SWITCH (n = 96), CRP, SAA, RF, and DAS28 at baseline showed predictive value for DAS28 remission in unadjusted analysis. Adjusted analysis confirmed SAA and DAS28 as predictive factors, with SAA having the highest value (ROC-AUC = 0.731). Furthermore, structural remission (ΔmTSS/year ≤ 0.5) rate was significantly higher in patients with SAA of < 50.0 µg/mL than other patients. In contrast, in ADD-ON (n = 98), only DAS28 showed predictive value for DAS28 remission. In patients with SAA < 50.0 µg/mL, both DAS28 remission and structural remission rate were comparable between SWITCH and ADD-ON.Conclusion: RA patients with low SAA levels at baseline may benefit similarly from tocilizumab with and without methotrexate.Trial registration number: NCT01120366.

Validation of the fibrosis-4 (FIB-4) index in the diagnosis of liver disease of rheumatoid arthritis patients treated with methotrexate.

Objectives: To validate the usefulness of a hepatic fibrosis scoring system fibrosis-4 (FIB-4) index to diagnose liver diseases in rheumatoid arthritis (RA) patients treated with methotrexate (MTX).Methods: The FIB-4 index (age(years) × AST(U/L)/platelet (PLT) (109/L) × âˆšALT(U/L)), proposed as a predictor for liver fibrosis in HIV/HCV coinfection, was evaluated in this study. RA patients on MTX treatment were screened by FIB-4 index values to detect fibrotic change in the liver. Liver biopsy specimens were examined histologically in patients with high values.Results: Thirteen of 14 patients showed histology closely resembling non-alcoholic steatohepatitis. In three of them, two biopsies were performed: 1st, during MTX treatment; and 2nd, after discontinuation of MTX. All of them showed improvement in histology along with decreased FIB-4 values. Age, AST/√ALT, and 1/PLT, as well as creatinine levels and cumulative MTX doses were significantly higher in the high FIB-4 group compared with the low FIB-4 group. In the high FIB-4 group, 1/PLT and AST/√ALT were significantly correlated with FIB-4 values, but age was not.Conclusions: The FIB-4 index is simple to calculate and a valuable marker to diagnose liver disease in RA patients treated with long-term MTX administration.

Tocilizumab discontinuation after attaining remission in patients with rheumatoid arthritis who were treated with tocilizumab alone or in combination with methotrexate: results from a prospective randomised controlled study (the second year of the SURPRISE study).

OBJECTIVE: To evaluate the sustained remission and low disease activity after discontinuation of tocilizumab in patients with rheumatoid arthritis who were treated with tocilizumab alone or in combination with methotrexate. METHODS: The SURPRISE study was a 2-year, open-label randomised controlled study. Among patients who had been randomised to additional tocilizumab (ADD-ON) or switch to tocilizumab (SWITCH) in the first year, those who achieved remission based on the disease activity score for 28 joints (DAS28-ESR<2.6) discontinued tocilizumab at week 52 and were observed for the following 52 weeks. The endpoint of the second year included tocilizumab-free remission and low disease-activity rates, functional outcome, radiological outcomes assessed with the modified total Sharp score (mTSS) and safety. The efficacy of reinstituted tocilizumab/methotrexate was also evaluated. RESULTS: A total of 105 patients who achieved remission at week 52 discontinued tocilizumab; 51 in ADD-ON continued methotrexate and 54 in SWITCH received no disease-modifying antirheumatic drugs. Sustained DAS28 low disease-activity rates were significantly higher in ADD-ON than in SWITCH (55%vs27%, p=0.005). Sustained remission rates at week 104 were 24% for ADD-ON and 14% for SWITCH (p=0.29). Radiological progression was comparable between both groups (mTSS; 0.37vs0.64, p=0.36). The restart of tocilizumab induced remission in all except two patients after 36 weeks, irrespective of concomitant methotrexate. CONCLUSION: Sustained low disease activity after tocilizumab discontinuation could be maintained with continued methotrexate in more than half of the patients. Retreatment with tocilizumab led to remission in more than 90% of patients. TRIAL REGISTRATION NUMBER: NCT01120366; Results.

Incidence of hepatitis B virus reactivation in patients with resolved infection on immunosuppressive therapy for rheumatic disease: a multicentre, prospective, observational study in Japan.

BACKGROUND: Although the reactivation of hepatitis B virus (HBV) is recognised as a serious complication in patients with rheumatic disease (RD) receiving immunosuppressive drugs (ISDs), the incidence and risk factors for reactivation remain controversial. OBJECTIVES: To investigate the incidence and risk factors for HBV reactivation in patients with RD. METHODS: We performed a multicentre, observational, prospective study over 2 years in patients with resolved HBV infection. Patients with RD treated with a dose of ≥5 mg/day prednisolone and/or synthetic or biological ISDs with negative HB virus surface antigen and positive anti-HB virus surface antibody (HBsAb) and/or anti-HB virus core antibody (HBcAb) were enrolled. Quantitative HBV DNA results and related data were regularly recorded. RESULTS: Among 1042 patients, including 959 with rheumatoid arthritis, HBV DNA was detected in 35 (1.93/100 person-years), with >2.1 log copies/mL observed in 10 patients (0.55/100 person-years). None of the reactivated patients, including seven treated with a nucleic acid analogue, showed overt hepatitis. Low HBsAb titres and advanced age seemed to be risk factors for HBV reactivation; however, reactivation was observed in three patients with positive HBsAb and negative HBcAb test results. The risk of reactivation was lower with methotrexate but higher with prednisolone among the different types of ISDs. The intervals from the start of ISD to reactivation were relatively long (3-182 months; median, 66 months). CONCLUSIONS: The incidence of HBV reactivation with ISD use was 1.93/100 person-years in patients with RD with resolved HBV infection. No overt hepatitis was observed in the reactivated patients.

Comparison of adding tocilizumab to methotrexate with switching to tocilizumab in patients with rheumatoid arthritis with inadequate response to methotrexate: 52-week results from a prospective, randomised, controlled study (SURPRISE study).

OBJECTIVE: To compare the efficacy and safety between tocilizumab added to methotrexate and tocilizumab switched from methotrexate in patients with active rheumatoid arthritis (RA). METHODS: This is a 2-year randomised, controlled study. RA patients with moderate or high disease activity despite methotrexate were randomly assigned either to tocilizumab added to methotrexate (add-on) or tocilizumab switched from methotrexate (switch). The primary endpoint was the DAS28 remission rate at week 24. Secondary objectives included other clinical efficacy indices, radiological outcomes assessed with the van der Heijde-modified total Sharp scoring system (mTSS), and safety. RESULTS: Of 223 randomised patients, 83% completed 52 weeks. DAS28 remission rates at week 24 were 70% for add-on and 55% for switch (p=0.02), but they became comparable at week 52 (72% vs 70%, p=0.86). Structural remission rates (mTSS≤0.5) at week 52 were not different (66% vs 64%, p=0.92). However, clinically relevant radiographic progression rates (CRRP; mTSS≥3) tended to be higher with the switch than with the add-on (15% vs 7%, p=0.07). Radiographic progression in the CRRP patients was larger with the switch than with the add-on (9.0/year vs 5.0/year, p=0.04). The difference in the mean C-reactive protein of the CRRP patients was significant for the first 24 weeks (1.56 vs 0.49, p=0.001) but not for the following 28 weeks (0.10 vs 0.04, p=0.1). Overall safety was preferable in the switch group. CONCLUSIONS: In RA patients with inadequate response to methotrexate, tocilizumab added to methotrexate more rapidly suppressed inflammation than tocilizumab switched from methotrexate, leading to superior clinical efficacy and prevention of joint destruction. TRIAL REGISTRATION NUMBER: NCT01120366.

Clinical and structural remission rates increased annually and radiographic progression was continuously inhibited during a 3-year administration of tocilizumab in patients with rheumatoid arthritis: A multi-center, prospective cohort study by the Michinoku Tocilizumab Study Group.

OBJECTIVE: To evaluate the clinical and structural efficacy of tocilizumab (TCZ) during its long-term administration in patients with rheumatoid arthritis (RA). METHODS: In total, 693 patients with RA who started TCZ therapy were followed for 3 years. Clinical efficacy was evaluated by DAS28-ESR and Boolean remission rates in 544 patients. Joint damage was assessed by calculating the modified total Sharp score (mTSS) in 50 patients. RESULTS: When the reason for discontinuation was limited to inadequate response or adverse events, the 1-, 2-, and 3-year continuation rates were 84.0%, 76.8%, and 72.2%, respectively. The mean DAS28-ESR was initially 5.1 and decreased to 2.5 at 6 months and to 2.2 at 36 months. The Boolean remission rate was initially 0.9% and increased to 21.7% at 6 months and to 32.2% at 36 months. The structural remission rates (ΔmTSS/year ≤ 0.5) were 68.8%, 78.6%, and 88.9% within the first, second, and third years, respectively. The structural remission rate at 3 years (ΔmTSS ≤ 1.5) was 66.0%, and earlier achievement of swollen joint count (SJC) of 1 or less resulted in better outcomes. CONCLUSIONS: TCZ was highly efficacious, and bone destruction was strongly prevented. SJC was an easy-to-use indicator of joint destruction.

Prevalence of hepatitis B virus infection in patients with rheumatic diseases in Tohoku area: a retrospective multicenter survey.

Hepatitis B virus (HBV) reactivation has been increasingly recognized in patients receiving chemotherapy and immunosuppressive therapy; however, the prevalence of HBV infection and rate of HBV screening in patients with rheumatic diseases remains unclear. In this study, we aimed to assess the prevalence of HBV infection and fulminant HBV hepatitis in patients with rheumatic diseases. We also investigated the rate of HBV screening before immunosuppressive therapy in patients with rheumatic diseases. A retrospective questionnaire survey was conducted in the North-east area (Tohoku) of Japan. Questionnaires, comprising 6 questions, were sent to 318 rheumatologists in May 2010, and responses were gathered until June 2011. In total, 71 rheumatologists (22.3%) responded to the survey. We enrolled 7,650 patients with rheumatoid arthritis (RA) and 1,031 patients with systemic lupus erythematosus (SLE). When limited to institutes at which almost all (≥ 90%) patients were tested for HBV serology, 1.1% (40/3,580) patients with RA and 0.3% (3/1,128) patients with SLE were positive for hepatitis B surface antigen (HBsAg), and 25.2% (177/703) patients with RA and 13.7% (34/248) patients with SLE were positive for hepatitis B core antibody (HBcAb). About one-third of rheumatologists did not check HBsAg and more than half did not check hepatitis B surface antibody (HBsAb) or HBcAb at all before therapy. Fulminant HBV hepatitis was observed in 1 RA patient who was current HBV carrier. In conclusion, the prevalence of HBV infection is high in patients with RA and SLE. HBV screening before immunosuppressive therapy should be strictly performed.

Incidence Rates of Infections in Rheumatoid Arthritis Patients Treated with Janus Kinase or Interleukin-6 Inhibitors: Results of a Retrospective, Multicenter Cohort Study.

Objective: This study aimed to compare the incidence rates (IRs) of infections, including herpes zoster (HZ), in rheumatoid arthritis (RA) patients treated with Janus kinase inhibitors (JAKis) or interleukin-6 inhibitors (IL-6is). Methods: We retrospectively analyzed 444 RA patients treated using IL-6is (n = 283) or JAKis (n = 161). After adjusting for clinical characteristic imbalances by propensity score matching (PSM), we compared the IRs of infections including HZ between the JAKi and IL-6i groups. Results: Observational period: 1423.93 patient years (PY); median observational period: 2.51 years. After PSM, incidence rate ratios comparing JAKi with IL-6i were 3.45 (95% confidence interval [CI]: 1.48-9.04) for serious infections other than HZ indicating that the JAKi-treated group was more likely to develop serious infection than the IL-6i-treated group. Multivariate Cox regression analyses revealed that the use of prednisolone > 5.0 mg/day, coexisting interstitial lung disease (ILD), and diabetes mellitus (DM) were independent risk factors for serious infections. The crude IR for HZ was significantly higher in the JAKi group, but the difference between groups was not significant (IRR: 2.83, 95% CI: 0.87-10.96) in PSM analysis. Unadjusted and PSM analyses performed in our study showed increased IRs of serious infections in patients with RA treated with JAKis compared with those treated with IL-6is. Conclusions: The presence of ILD or DM and the use of prednisolone were found to be independent risk factors for serious infection in RA patients treated using JAKis. Whereas the IRs for HZ after PSM were not significantly different between the JAKi and IL-6i groups.

Comparison of CRISPR-Cas9-mediated megabase-scale genome deletion methods in mouse embryonic stem cells.

The genome contains large functional units ranging in size from hundreds of kilobases to megabases, such as gene clusters and topologically associating domains. To analyse these large functional units, the technique of deleting the entire functional unit is effective. However, deletion of such large regions is less efficient than conventional genome editing, especially in cultured cells, and a method that can ensure success is anticipated. Here, we compared methods to delete the 2.5-Mb Krüppel-associated box zinc finger protein (KRAB-ZFP) gene cluster in mouse embryonic stem cells using CRISPR-Cas9. Three methods were used: first, deletion by non-homologous end joining (NHEJ); second, homology-directed repair (HDR) using a single-stranded oligodeoxynucleotide (ssODN); and third, HDR employing targeting vectors with a selectable marker and 1-kb homology arms. NHEJ-mediated deletion was achieved in 9% of the transfected cells. Inversion was also detected at similar efficiency. The deletion frequency of NHEJ and HDR was found to be comparable when the ssODN was transfected. Deletion frequency was highest when targeting vectors were introduced, with deletions occurring in 31-63% of the drug-resistant clones. Biallelic deletion was observed when targeting vectors were used. This study will serve as a benchmark for the introduction of large deletions into the genome.

Hepatic failure in a patient with rheumatoid arthritis treated with methotrexate: A case report.

INTRODUCTION: Chronic liver damage from methotrexate (MTX) is not uncommon, and fatal outcome is rare. We experienced a case of hepatic failure leading to death. We considered the cause of death through this case and proposed a method to prevent the progression of this liver injury. PATIENT CONCERNS: We report the case of a patient with rheumatoid arthritis treated with MTX for 15 years. DIAGNOSIS, INTERVENTIONS, AND OUTCOMES: A liver biopsy revealed histological changes similar to those of advanced nonalcoholic steatohepatitis (NASH), most likely induced by MTX. MTX was discontinued after 4 years. Two years after the discontinuation, the patient died of irreversible hepatic failure. Her obesity, complicated by type 2 diabetes mellitus, might have aggravated MTX-induced NASH-like liver injury. CONCLUSION: Early diagnosis and immediate MTX discontinuation following NASH diagnosis and strict type 2 diabetes mellitus control might have prevented the irreversible progression of liver injury.

Enzyme replacement therapy in two patients with classic Fabry disease from the same family tree: Two case reports.

BACKGROUND: The pathophysiology of Fabry disease (FD)-induced progressive vital organ damage is irreversible. Disease progression can be delayed using enzyme replacement therapy (ERT). In patients with classic FD, sporadic accumulation of globotriaosylceramide (GL-3) in the heart and kidney begins in utero; however, until childhood, GL-3 accumulation is mild and reversible and can be restored by ERT. The current consensus is that ERT initiation during early childhood is paramount. Nonetheless, complete recovery of organs in patients with advanced FD is challenging. CASE SUMMARY: Two related male patients, an uncle (patient 1) and nephew (patient 2), presented with classic FD. Both patients were treated by us. Patient 1 was in his 50s, and ERT was initiated following end-organ damage; this was subsequently ineffective. He developed cerebral infarction and died of sudden cardiac arrest. Patient 2 was in his mid-30s, and ERT was initiated when the patient was diagnosed with FD, during which the damage to vital organs was not overtly apparent. Although he had left ventricular hypertrophy at the beginning of this treatment, the degree of hypertrophy progression was limited to a minimal range after > 18 years of ERT. CONCLUSION: We obtained discouraging ERT outcomes for older patients but encouraging outcomes for younger adults with classic FD.

Drug Retention Rates and the Safety of Janus Kinase Inhibitors in Elderly Patients with Rheumatoid Arthritis.

BACKGROUND: We examined the real-world drug retention rate and safety data of Janus kinase inhibitors (JAKis) in elderly patients with rheumatoid arthritis (RA). METHODS: This study enrolled 133 RA patients (≥65 years) with sufficient clinical data who were initiated with JAKis during the study period. These patients were divided into two groups: the very elderly group (≥ 75 years) and the elderly group (65 ≤ years < 75). The drug retention rates of JAKis were compared using Kaplan-Meier curves. RESULTS: The discontinuation rates of JAKis were as follows: lack of effectiveness 27 (20.3%), adverse events (AEs) 29 (21.8%), and remission 2 (1.5%). There was no significant difference in the overall drug retention rate between the very elderly group (≥75 years) and the elderly group. Furthermore, the overall drug retention rates of JAKis were not affected by gender, methotrexate use, and anti-citrullinated protein/peptide antibody (ACPA) status. The discontinuation rates of JAKis due to AEs were comparable both in the very elderly group (≥75 years) and the elderly group (65 ≤ years < 75). Whereas chronic lung disease and hypoalbuminemia were independently associated with discontinuation rates due to AEs, the overall drug retention rates were significantly lower in patients treated with the approved dose of JAKis than in those treated with a reduced or tapered dose. CONCLUSIONS: Our results suggest that the overall drug retention rate of JAKis in very elderly patients (≥75 years) was comparable with that in elderly patients (65 ≤ years < 75). The discontinuation rates of JAKis due to AEs were also comparable both in very elderly group patients and elderly patients.

Drug Retention Rates of Janus Kinase Inhibitors in Rheumatoid Arthritis Patients with Therapy-Induced Lymphopenia.

OBJECTIVES: To determine whether drug-induced lymphocytopenia is associated with drug retention rates of JAKi (tofacitinib or baricitinib) in rheumatoid arthritis (RA) patients. METHODS: Patients with RA who were initiated with tofacitinib (n = 38) or baricitinib (n = 74) between July 2015 and July 2022 and continued for at least 4 months were enrolled in this study. Absolute lymphocyte count (ALC) value was obtained pre-treatment and monthly after initiation of JAKi (up to 4 months). Associations between ALC nadir at an early phase (up to 4 months) from JAKi initiation and drug retention rates were analysed. RESULTS: 112 patients (87 females; age, 71.2 ± 14.0 years; disease duration, 9.2 ± 10.5 months; DAS28-CRP, 3.60 ± 1.12; DAS28-ESR, 4.43 ± 1.29; CDAI, 17.9 ± 12.9; C-reactive protein, 3.07 ± 3.43 mg/dL; and lymphocyte count, 1361.9 ± 538.7 per µL) treated with tofacitinib or baricitinib were retrospectively analysed. Lymphocytopenia (>10% decline in lymphocyte count to pre-treatment basal levels) was observed in a quarter of RA patients treated with JAKi (tofacitinib; 16 baricitinib; 14). RA patients with lymphopenia were associated with the lower drug retention rates of tofacitinib compared to those without lymphocytopenia. The reduced drug retention rates in patients with lymphocytopenia were attributed to the discontinuation of tofacitinib due to AEs. Whereas lymphocytopenia was not associated with lower drug retention rates of baricitinib. Pre-treatment absolute lymphocyte counts did not affect the drug retention rates of JAKi in patients with RA. CONCLUSIONS: These findings suggest that lymphopenia during the first 4 months from the initiation of JAKi is associated with reduced drug retention rates in patients with RA due to AEs, which is exclusively associated with the use of tofacitinib.

Safety of JAK and IL-6 inhibitors in patients with rheumatoid arthritis: a multicenter cohort study.

Background: The ORAL Surveillance trial showed a potentially higher incidence of malignancy and major adverse cardiovascular events (MACEs) associated with tofacitinib than those associated with tumor necrosis factor (TNF) inhibitors (TNFis). However, few studies have compared the safety of non-TNFis or other Janus kinase (JAK) inhibitors (JAKis). This study was aimed at comparing the incidence rates (IRs) of malignancies and MACEs in patients with rheumatoid arthritis (RA) treated using interleukin-6 (IL-6) inhibitors (IL-6is) or JAKis. Methods: We retrospectively analyzed 427 patients with RA who were treated using an IL-6i (n = 273) or a JAKi (n = 154). We determined the IRs of malignancy and MACEs, and the standardized incidence ratio (SIR) of malignancies and investigated factors related to malignancy and MACEs. After adjusting the clinical characteristic imbalance by propensity score matching (PSM), we compared the IRs of adverse events between the JAKi and IL-6i groups. Results: After PSM, the observational period was determined to be 605.27 patient-years (PY), and the median observational period was determined to be 2.28 years. We identified seven cases of malignancy (IR: 2.94 per 100 PY) in the JAKi-treated group and five cases (IR: 1.36 per 100 PY) in the IL-6i-treated group after PSM. The IR of MACEs was 2.56 and 0.83 (per 100 PY) in the JAKi- and IL-6i-treated groups. The IRRs of JAKi-treated patients versus IL-6i-treated patients were 2.13 (95% confidence interval (CI): 0.67-7.42) for malignancy and 3.03 (95% CI: 0.77-15.21) for MACE. There were no significant differences in IRR for malignancy and MACE between both groups after PSM. Univariate and multivariable Cox regression analyses revealed that older age and JAKi use were independent risk factors for malignancy, while older age, hypertension, and JAKi use were independent risk factors for MACEs. The overall malignancy SIR was significantly higher in the JAKi-treated group compared to the general population (2.10/100 PY, 95% CI: 1.23-2.97). Conclusion: The IRs of malignancy and MACE in patients with RA after PSM were comparable between IL-6i-treated and JAKi-treated patients. However, the SIR of malignancy in JAKi treatment was significantly higher than in the general population; therefore, further safety studies comparing JAKi to non-TNFi biologic disease-modifying antirheumatic drugs (bDMARDs) are needed.

Feasibility of methotrexate discontinuation following tocilizumab and methotrexate combination therapy in patients with long-standing and advanced rheumatoid arthritis: a 3-year observational cohort study.

OBJECTIVES: Methotrexate (MTX) is associated with extensive side effects, including myelosuppression, interstitial pneumonia, and infection. It is, therefore, critical to establish whether its administration is required after achieving remission with tocilizumab (TCZ) and MTX combination therapy in patients with rheumatoid arthritis (RA). Therefore, the aim of this multicenter, observational, cohort study was to evaluate the feasibility of MTX discontinuation for the safety of these patients. METHODS: Patients with RA were administered TCZ, with or without MTX, for 3 years; those who received TCZ+MTX combination therapy were selected. After remission was achieved, MTX was discontinued without flare development in one group (discontinued [DISC] group, n = 33) and continued without flare development in another group (maintain [MAIN] group, n = 37). The clinical efficacy of TCZ+MTX therapy, patient background characteristics, and adverse events were compared between groups. RESULTS: The disease activity score in 28 joints-erythrocyte sedimentation rate (DAS28-ESR) at 3, 6, and 9 months was significantly lower in the DISC group (P < .05, P < .01, and P < .01, respectively). Further, the DAS28-ESR remission rate at 6 and 9 months and Boolean remission rate at 6 months were significantly higher in the DISC group (P < .01 for all). Disease duration was significantly longer in the DISC group (P < .05). Furthermore, the number of patients with stage 4 RA was significantly higher in the DISC group (P < .01). CONCLUSIONS: Once remission was achieved, MTX was discontinued in patients who responded favorably to TCZ+MTX therapy, despite the prolonged disease duration and stage progression.

Real-world comparative effectiveness of bDMARDs and JAK inhibitors in elderly patients with rheumatoid arthritis.

In this retrospective cohort study, we compared the retention rates and effectiveness of biologic disease modifying antirheumatic drugs (bDMARDs) and targeted synthetic DMARDs (targeted disease modifying antirheumatic drug [tsDMARDs]: Janus kinase inhibitors [JAKi]) in elderly patients with RA. One hundred thirty-four elderly RA patients (≥65 years) who were initiated with bDMARDs (n = 80) or JAKi (n = 54) between 2016 and 2020 in our institute were enrolled in this analysis. Follow-up was conducted at 4-week intervals from the start of bDMARDs or JAKi. We compared the drug retention and clinical response at 24 week between elderly RA patients treated with bDMARDs and JAKi. In the demographic data, more disease duration, the proportion of previous bDMARDs use and less the proportion of glucocorticoid use in JAKi group was significantly observed compared to the bDMARDs group. Otherwise, there was no significant difference in the other variables between the bDMARDs and JAKi groups. In the JAKi group, drug retention rate was not significantly different compared to the bDMARDs group (HR: 0.723, 95% CI: 0.406-1.289, P = .266). Also, there was no significant difference in the proportion of patients achieving good or moderate European alliance of associations for rheumatology (EULAR) response at 24 week between these two groups (bDMARDs; 88.6% vs JAKi; 91.8%, P = .158). In elderly RA patients initiated with bDMARDs or JAKi, drug retention rates of these targeted therapies did not differ significantly between these two groups. These findings suggest that elderly RA patients can achieve similar clinical improvement after initiating bDMARDs or JAKi.

Comparing the effectiveness and safety of Abatacept and Tocilizumab in elderly patients with rheumatoid arthritis.

BACKGROUND: The number of biological DMARDs (bDMARDs) used in elderly patients with rheumatoid arthritis (RA) has increased in recent years. We aimed to compare the drug retention rates and safety of abatacept (ABT) and tocilizumab (TCZ) in elderly patients with RA. METHODS: A total 125 elderly patients with RA (>65 years) who began therapy with either ABT (n = 47) or TCZ (n = 78) between 2014 and 2021 at our institute were enrolled. We compared the drug retention rate and clinical response at 24 weeks between elderly patients with RA treated with ABT and those treated with TCZ. Adverse events (AEs) and the reasons for drug discontinuation were assessed. RESULTS: There was no significant difference in demographic characteristics except for the use of glucocorticoid between the ABT and TCZ groups. There was no significant difference in the drug retention rate between the ABT and TCZ groups. Furthermore, there was no significant difference in the discontinuation rates due to the lack of effectiveness between these two groups. The proportions of the patients archiving low disease activity at 24 weeks did not differ significantly between the two groups. Whereas, the discontinuation rates due to AEs, including interstitial lung disease (ILD), seemed higher in the TCZ group than in the ABT group. In TCZ-treated group, the concomitant use of methotrexate (MTX) significantly increased the incidences of AEs leading to the discontinuation of TCZ. Whereas these was no significant impact of concomitant use of MTX on the incidences of AEs leading to discontinuation in ABT-treated group. CONCLUSIONS: In elderly patients with RA treated with ABT and TCZ, drug retention rates were equivalent between the two groups. There were some differences in safety profiles between ABT and TCZ, and the rates of discontinuation due to AEs, including ILD, seem to be lower with ABT than with TCZ in elderly patients with RA.

NADP(H) allosterically regulates the interaction between ferredoxin and ferredoxin-NADP+ reductase.

Ferredoxin-NADP+ reductase (FNR) in plants receives electrons from ferredoxin (Fd) at the end of the photosynthetic electron transfer chain and converts NADP+ to NADPH. The interaction between Fd and FNR in plants was previously shown to be attenuated by NADP(H). Here, we investigated the molecular mechanism of this phenomenon using maize FNR and Fd, as the three-dimensional structure of this complex is available. NADPH, NADP+ , and 2'5'-ADP differentially affected the interaction, as revealed through kinetic and physical binding analyses. Site-directed mutations of FNR which change the affinity for NADPH altered the affinity for Fd in the opposite direction to that for NADPH. We propose that the binding of NADP(H) causes a conformational change of FNR which is transferred to the Fd-binding region through different domains of FNR, resulting in allosteric changes in the affinity for Fd.