Matching-adjusted comparison of oral corticosteroid reduction in asthma: Systematic review of biologics.

BACKGROUND: Oral corticosteroid (OCS) treatment for severe asthma is associated with substantial disease burden. Thus, OCS dosage reduction is desirable. Relative efficacy of biologics in reducing OCS treatment for severe, uncontrolled asthma is not fully characterized. OBJECTIVE: We performed a matching-adjusted indirect comparison (MAIC) to assess the relative effects on OCS treatment reduction of three biologic asthma treatments. METHODS: In MAIC of benralizumab vs. mepolizumab and vs. dupilumab, patient-level data from the Phase III benralizumab OCS-sparing trial, ZONDA, were weighted to match treatment effect-modifying patient characteristics in comparator trials. RESULTS: After matching adjustment, mean difference between benralizumab and mepolizumab for OCS reduction was 6.08% (95% CI -22.22-34.38; P = .67) by week 24, and odds ratio of OCS elimination was 2.32 (95% CI 0.48-11.15; P = .29). A trend in annual asthma exacerbation rate reduction favouring benralizumab over mepolizumab was observed, although it was not statistically significant (rate ratio [RR] = 0.56 [95% CI 0.28-1.13; P = .11]). Mean difference between benralizumab and dupilumab for OCS reduction was -0.71% (95% CI -20.56-19.15; P = .94), and odds ratio of OCS elimination was 2.26 (95% CI 0.52-9.84; P = .28). A non-significant trend in annual asthma exacerbation rate reduction favouring benralizumab over dupilumab was observed (RR = 0.50 [95% CI 0.20-1.28; P = .15]). Effective sample size was 49% (72 vs. 148) and 25% (36 vs. 142) of original sample size for MAIC of benralizumab vs. mepolizumab and benralizumab vs. dupilumab, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Following patient baseline characteristics matching across clinical trials, benralizumab demonstrated efficacy comparable to mepolizumab and dupilumab for OCS dosage reduction, OCS elimination, and annual exacerbation rate reduction. Comparatively low effective sample sizes indicated substantial differences for patient populations between ZONDA and mepolizumab and dupilumab trials.

Healthcare resource utilization and costs associated with incremental systemic corticosteroid exposure in asthma.

BACKGROUND: Although systemic corticosteroid (SCS) treatment, irrespective of duration or dosage, is associated with adverse outcomes for patients with asthma, the longitudinal effects of this treatment on adverse outcomes, healthcare resource utilization (HCRU), and healthcare costs are unknown. METHODS: We identified patients initiating intermittent or long-term SCS who were diagnosed with active asthma from UK general practice with linked secondary care data. Control (non-SCS) patients were matched by sex and index date with those initiating SCS. Minimum baseline period was 1 year prior to index date; minimum follow-up duration was 2 years post-index date. Cumulative incidence of SCS-associated adverse outcomes and associated HCRU and costs were compared between SCS and non-SCS patient groups and among average SCS daily exposure categories. Associations between exposure and annualized HCRU and costs were assessed, adjusted for confounders. RESULTS: Analyses included 9413 matched pairs. Median (interquartile range) follow up was as follows: SCS group: 7.1 (4.1-11.8) years; control group: 6.4 (3.8-10.0) years. Greater SCS dosages were correlated with greater cumulative incidence. For example, patients with type 2 diabetes receiving an average daily dosage of ≥7.5 mg had a 15-year cumulative incidence (37.5%) that was 1.5-5 times greater than those receiving lower dosages. HCRU and costs increased annually for SCS patients but not for non-SCS patients. Increases in all-cause adverse outcome (excluding asthma)-associated HCRU and costs were dose-dependent. CONCLUSIONS: Over the long term, adverse outcomes associated with SCS initiation were relatively frequent and costly, with a positive dosage-response relationship with SCS exposure.

Healthcare resource use and costs of severe, uncontrolled eosinophilic asthma in the UK general population.

BACKGROUND: Little is known about the prevalence of severe, uncontrolled eosinophilic asthma (SUEA) and associated costs. AIMS: We sought to determine the prevalence of SUEA and compare asthma-related healthcare resource use (HCRU) and associated costs with overall means for a general asthma population. METHODS: This cohort study evaluated anonymised medical record data (December 1989 through June 2015) from the Clinical Practice Research Datalink and the Optimum Patient Care Research Database to study UK patients with active asthma (diagnostic code and one or more drug prescriptions in the baseline year), aged 5 years and older, without concomitant COPD, and with recorded eosinophil count. SUEA was defined as two or more asthma attacks during 1 baseline year preceding a high blood eosinophil count (≥0.3×109/L) for patients prescribed long-acting ß2-agonist (LABA) and high-dosage inhaled corticosteroids (ICS) during baseline plus 1 follow-up year. We compared asthma-related HCRU and associated direct costs (2015 pounds sterling, £) during the follow-up year for SUEA versus the general asthma population. RESULTS: Of 363 558 patients with active asthma and recorded eosinophil count, 64% were women, mean (SD) age was 49 (21) years; 43% had high eosinophil counts, 7% had two or more attacks in the baseline year and 10% were prescribed high-dosage ICS/LABA for 2 study years. Overall, 2940 (0.81%; 95% CI 0.78% to 0.84%) patients had SUEA. Total mean per-patient HCRU and associated costs were four times greater for SUEA versus all patients (HCRU and cost ratios 3.9; 95% CI 3.7 to 4.1). CONCLUSIONS: Less than 1% of patients in a general asthma population had SUEA. These patients accounted for substantially greater asthma-related HCRU and costs than average patients with asthma.

Matching-adjusted indirect comparison of benralizumab versus interleukin-5 inhibitors for the treatment of severe asthma: a systematic review.

Benralizumab is an interleukin-5 receptor α-directed cytolytic monoclonal antibody that directly depletes eosinophils. Its relative efficacy versus other IL-5-targeted treatments for patients with severe, uncontrolled asthma is not yet fully characterised.We performed a matching-adjusted indirect comparison (MAIC) of benralizumab versus mepolizumab and reslizumab. Trials were selected through systematic review and evaluation of trial methods. Benralizumab patient-level data were weighted to match treatment-effect-modifying patient characteristics of comparator trials before indirect efficacy comparisons.After matching adjustment, benralizumab and mepolizumab reduced exacerbations versus placebo by 52% and 49%, respectively (rate ratio [RR] 0.94, 95% CI 0.78-1.13; n=1524) and reduced the rate of exacerbations requiring hospitalisation/emergency department visit by 52% and 52%, respectively (RR 1.00, 95% CI 0.57-1.75; n=1524). Benralizumab and mepolizumab similarly improved pre-bronchodilator forced expiratory volume in 1 s at 32 weeks (difference 0.03 L, 95% CI -0.06-0.12; n=1443). Benralizumab and reslizumab patient populations were too dissimilar to generate a sufficient effective sample size to produce a reliable estimate for MAIC.MAIC is a robust way to indirectly compare treatment efficacies from trials with heterogeneous patient populations. When baseline patient characteristics were matched across asthma trials, benralizumab and mepolizumab yielded similar efficacy.

Adverse Outcomes, Healthcare Resource Utilization, and Costs Associated with Systemic Corticosteroid use Among Adults with Systemic Lupus Erythematosus in the UK.

INTRODUCTION: This analysis was conducted to assess the incidence of adverse clinical outcomes, healthcare resource use (HCRU), and the costs associated with systemic corticosteroid (SCS) use in adults with systemic lupus erythematosus (SLE) in the UK. METHODS: We identified incident SLE cases using the Clinical Practice Research Datalink GOLD, Hospital Episode Statistics-linked healthcare, and Office for National Statistics mortality databases from January 1, 2005, to June 30, 2019. Adverse clinical outcomes, HCRU, and costs were captured for patients with and without prescribed SCS. RESULTS: Of 715 patients, 301 (42%) had initiated SCS use (mean [standard deviation (SD)] 3.2 [6.0] mg/day) and 414 (58%) had no recorded SCS use post-SLE diagnosis. Cumulative incidence of any adverse clinical outcome over 10-year follow-up was 50% (SCS group) and 22% (non-SCS group), with osteoporosis diagnosis/fracture most frequently reported. SCS exposure in the past 90 days was associated with an adjusted hazard ratio of 2.41 (95% confidence interval 1.77-3.26) for any adverse clinical outcome, with increased hazard for osteoporosis diagnosis/fracture (5.26, 3.61-7.65) and myocardial infarction (4.52, 1.16-17.71). Compared to low-dose SCS (< 7.5 mg/day), patients on high-dose SCS (≥ 7.5 mg/day) had increased hazard for myocardial infarction (14.93, 2.71-82.31), heart failure (9.32, 2.45-35.43), osteoporosis diagnosis/fracture (5.14, 2.82-9.37), and type 2 diabetes (4.02 1.13-14.27). Each additional year of SCS use was associated with increased hazard for any adverse clinical outcome (1.15, 1.05-1.27). HCRU and costs were greater for SCS users than non-SCS users. CONCLUSIONS: Among patients with SLE, there is a higher burden of adverse clinical outcomes and greater HCRU in SCS versus non-SCS users.

Healthcare Resource Use and Costs Associated with Organ Damage in Newly Diagnosed Adults with Systemic Lupus Erythematosus in the UK.

INTRODUCTION: This analysis compared healthcare resource use (HCRU) and costs associated with incident organ damage in a cohort of adult patients with systemic lupus erythematosus (SLE). METHODS: Incident SLE cases were identified (Clinical Practice Research Datalink [CPRD] and Hospital Episode Statistics-linked healthcare databases; January 1, 2005-June 30, 2019). Annual incidence of 13 organ damage domains was calculated from SLE diagnosis through follow-up. Annualized HCRU and costs were compared between organ damage and non-organ damage patient groups using generalized estimating equations. RESULTS: A total of 936 patients met the inclusion criteria for SLE. Mean age was 48.0 (standard deviation [SD] 15.7) years and 88% were female. Over a median follow-up period of 4.3 (interquartile range [IQR] 1.9-7.0) years, 59% (315/533) had evidence of post-SLE diagnosis incident organ damage (≥ 1 type), which was greatest for musculoskeletal (146/819 [18%]), cardiovascular (149/842 [18%]), and skin (148/856 [17%]) domains. Patients with organ damage had greater resource use for all organ systems, excluding gonadal, versus those without it. Overall, mean (SD) annualized all-cause HCRU was greater in patients with organ damage versus those without it (inpatient, 1.0 versus 0.2; outpatient, 7.3 versus 3.5; accident and emergency, 0.5 versus 0.2 days; primary care contacts, 28.7 versus 16.5; prescription medications, 62.3 versus 22.9). Adjusted mean annualized all-cause costs were significantly greater in both post- and pre-organ damage index periods for patients with organ damage versus those without it (all P < 0.05, excluding gonadal). Overall organ damage was associated with significantly increased adjusted mean annualized per-patient cost (£4442 greater [P < 0.0001]) ranging between £2709 and £7150 greater depending on the organ damage type. CONCLUSION: Organ damage was associated with higher HCRU and healthcare costs, before and after SLE diagnosis. More effective SLE management may slow disease progression, prevent organ damage onset, improve clinical outcomes, and reduce healthcare costs.

Indirect treatment comparison of anifrolumab efficacy versus belimumab in adults with systemic lupus erythematosus.

Aim: Assess the comparative efficacy of anifrolumab 300 mg versus belimumab 10 mg/kg in adults with moderate-to-severe systemic lupus erythematosus (SLE) receiving standard therapy. Patients and methods: Population-adjusted simulated treatment comparisons (primary analyses) and matching-adjusted indirect comparisons (supporting analyses) were conducted using individual patient data from TULIP-1/TULIP-2 and summary-level data from BLISS-52/BLISS-76. Results: Compared with belimumab-treated patients, anifrolumab-treated patients were more than twice as likely to achieve a reduction of four or more points in SLE Disease Activity Index 2000 score (simulated treatment comparison odds ratio: 2.47; 95% CI: 1.16-5.25) and SLE Responder Index-4 response (odds ratio: 2.61; 95% CI: 1.22-5.58) at 52 weeks. Conclusion: Patients with moderate-to-severe SLE are more likely to achieve an improvement in disease activity with anifrolumab than with belimumab.

The burden of mild asthma: Clinical burden and healthcare resource utilisation in the NOVELTY study.

BACKGROUND: Patients with mild asthma represent a substantial proportion of the population with asthma, yet there are limited data on their true burden of disease. We aimed to describe the clinical and healthcare resource utilisation (HCRU) burden of physician-assessed mild asthma. METHODS: Patients with mild asthma were included from the NOVEL observational longiTudinal studY (NOVELTY; NCT02760329), a global, 3-year, real-world prospective study of patients with asthma and/or chronic obstructive pulmonary disease from community practice (specialised and primary care). Diagnosis and severity were based on physician discretion. Clinical burden included physician-reported exacerbations and patient-reported measures. HCRU included inpatient and outpatient visits. RESULTS: Overall, 2004 patients with mild asthma were included; 22.8% experienced ≥1 exacerbation in the previous 12 months, of whom 72.3% experienced ≥1 severe exacerbation. Of 625 exacerbations reported, 48.0% lasted >1 week, 27.7% were preceded by symptomatic worsening lasting >3 days, and 50.1% required oral corticosteroid treatment. Health status was moderately impacted (St George's Respiratory Questionnaire score: 23.5 [standard deviation ± 17.9]). At baseline, 29.7% of patients had asthma symptoms that were not well controlled or very poorly controlled (Asthma Control Test score <20), increasing to 55.6% for those with ≥2 exacerbations in the previous year. In terms of HCRU, at least one unscheduled ambulatory visit for exacerbations was required by 9.5% of patients, including 9.2% requiring ≥1 emergency department visit and 1.1% requiring ≥1 hospital admission. CONCLUSIONS: In this global sample representing community practice, a significant proportion of patients with physician-assessed mild asthma had considerable clinical burden and HCRU.

Cell behaviors within a confined adhesive area fabricated using novel micropatterning methods.

In the field of cell and tissue engineering, there is an increasing demand for techniques to spatially control the adhesion of cells to substrates of desired sizes and shapes. Here, we describe two novel methods for fabricating a substrate for adhesion of cells to a defined area. In the first method, the surface of the coverslip or plastic dish was coated with Lipidure, a non-adhesive coating material, and air plasma was applied through a mask with holes, to confer adhesiveness to the surface. In the second method, after the surface of the coverslip was coated with gold by sputtering and then with Lipidure; the Lipidure coat was locally removed using a novel scanning laser ablation method. These methods efficiently confined cells within the adhesive area and enabled us to follow individual cells for a longer duration, compared to the currently available commercial substrates. By following single cells within the confined area, we were able to observe several new aspects of cell behavior in terms of cell division, cell-cell collisions, and cell collision with the boundary between adhesive and non-adhesive areas.

The cost-effectiveness of as-needed budesonide-formoterol versus low-dose inhaled corticosteroid maintenance therapy in patients with mild asthma in Canada.

BACKGROUND: The Global Initiative for Asthma recommends the use of as-needed low-dose inhaled corticosteroid (ICS)-formoterol as a preferred controller therapy for patients with mild asthma. These recommendations were based, in part, on evidence from the SYGMA 1 and 2 studies of as-needed budesonide-formoterol. This analysis aimed to compare the cost-effectiveness of as-needed budesonide-formoterol to low-dose maintenance ICS plus as-needed short-acting ß2-agonist (SABA) in patients with mild asthma. METHODS: A Markov cohort model was designed that included three possible health states (non-exacerbation, severe exacerbation, and death) to compare as-needed budesonide-formoterol 200-6 µg to twice-daily budesonide 200 µg maintenance therapy (low-dose ICS) plus as-needed terbutaline 0.5 mg (SABA). The deterministic base-case analysis used severe exacerbation, adverse event (AE), and healthcare resource use data from SYGMA 2, and was conducted from a Canadian public payer perspective with a 50-year time horizon, and a discount rate of 1.5% per annum. Moderate exacerbation was modelled on data from SYGMA 1 in sensitivity analyses. Utility values were derived from SYGMA 2 quality of life data. All-cause- and asthma-related mortality rates and costs (reported in 2019 Canadian dollars) were based on published data, using Canada-specific values where available. One-way deterministic sensitivity, probabilistic sensitivity, and eight scenario analyses were conducted to examine the robustness of the results. RESULTS: As-needed budesonide-formoterol was the dominant treatment option in the base-case analysis, providing incremental cost savings of $9882 per patient and quality-adjusted life year (QALY) gains of 0.002 versus low-dose maintenance ICS plus as-needed SABA over a 50-year time horizon. Using a willingness-to-pay threshold of $50,000/QALY ($100,000/QALY), as-needed budesonide-formoterol had a 94% (95%) probability of being cost-effective compared with maintenance ICS plus as-needed SABA. Cost-saving was mostly driven by lower overall medication and AE-related costs. As-needed budesonide-formoterol remained the dominant treatment in sensitivity and scenario analyses. CONCLUSIONS: As-needed budesonide-formoterol is a cost-saving option for the treatment of mild asthma from the perspective of the Canadian public payer compared with low-dose maintenance ICS plus as-needed SABA.

Cost effectiveness of benralizumab for severe, uncontrolled oral corticosteroid-dependent asthma in Sweden.

Aim: We investigated cost effectiveness of benralizumab vs. standard of care (SOC) plus oral corticosteroids (OCS) for patients with severe, eosinophilic OCS-dependent asthma in Sweden.Materials and methods: A three-state, cohort-based Markov model of data from three Phase III benralizumab clinical trials (ZONDA [NCT02075255], SIROCCO [NCT01928771], and CALIMA [NCT01914757]) was used to assess the incremental cost-effectiveness ratio of benralizumab vs. SOC plus OCS. Health outcomes were estimated in terms of quality-adjusted life-years (QALYs). The model included costs and disutilities associated with extrapolated OCS-related adverse events. Patients with severe asthma were defined as those receiving OCS ≥5 mg/day.Results: Benralizumab demonstrated a cost-effectiveness ratio vs. SOC plus OCS of 2018 Swedish Kronor (SEK) 366,855 (€34,127) per QALY gained, based on increases of 1.33 QALYs and SEK 488,742 (€45,344) per patient. Benralizumab treatment costs contributed most to incremental costs. The probability of benralizumab's being cost-effective with willingness-to-pay (WTP) thresholds between SEK 429,972 (€40,000) and SEK 752,452 (€70,000) ranged from 75% to 99%.Limitations: Potential limitations of these analyses include the use of combined data from three different clinical trials, a one-way sensitivity analysis that did not include mortality and transition estimates, and Observational & Pragmatic Research Institute (OPRI) data from the UK as a proxy of the Swedish health care system.Conclusions: The results of these analyses demonstrate that benralizumab has a high probability of being cost-effective compared with SOC plus OCS for a subgroup of patients with severe, eosinophilic asthma receiving regular OCS treatment and may support clinicians, payers and patients in making treatment decisions.

The cost-effectiveness of as-needed budesonide/formoterol versus low-dose inhaled corticosteroid maintenance therapy in patients with mild asthma in the UK.

BACKGROUND: As-needed budesonide/formoterol is effective in patients with mild asthma for whom low-dose inhaled corticosteroid (ICS) maintenance therapy is appropriate. We assessed the cost-effectiveness of this regimen versus maintenance low-dose ICS plus as-needed short-acting ß2-agonist (SABA). METHODS: A probabilistic Markov cohort model was developed that simulated time within/outside severe asthma exacerbations, conducted from a UK NHS perspective with a 70-year time horizon. Clinical efficacy inputs were derived from the SYGMA 2 trial. Patients with mild asthma eligible for low-dose maintenance ICS therapy received as-needed budesonide/formoterol 200/6 µg or twice-daily budesonide 200 µg maintenance therapy plus as-needed terbutaline 0.5 mg. A severe exacerbation was defined as worsening asthma requiring systemic corticosteroid use alone/in combination with an emergency department visit, or hospitalisation for acute asthma. Utility values were derived from SYGMA 2 EQ-5D-5L data, and all-cause- and asthma-related mortality, reduction in utility of an exacerbation, and costs were based on published data. The base-case analysis discount rate was 3.5%. Model robustness was evaluated with one-way sensitivity, probabilistic sensitivity, and two scenario analyses. RESULTS: On average, as-needed budesonide/formoterol was associated with a £292.99 cost saving and quality-adjusted life year (QALY) gains of 0.001 versus ICS + SABA. At a willingness-to-pay of £20,000/QALY, as-needed budesonide/formoterol had >85% probability of being cost-effective versus ICS + SABA. Key drivers were budesonide/formoterol and budesonide maintenance annual exacerbation rates, mean daily budesonide/formoterol inhalations, and costs and outcomes discount rates. CONCLUSIONS: From a UK healthcare payer perspective, as-needed budesonide/formoterol is a cost-effective option for the treatment of mild asthma versus regular ICS.

Cytokinesis D is Mediated by Cortical Flow of Dividing Cells Instead of Chemotaxis.

Cytokinesis D is known as the midwife mechanism in which neighboring cells facilitate cell division by crossing the cleavage furrow of dividing cells. Cytokinesis D is thought to be mediated by chemotaxis, where midwife cells migrate toward dividing cells by sensing an unknown chemoattractant secreted from the cleavage furrow. In this study, to validate this chemotaxis model, we aspirated the fluid from the vicinity of the cleavage furrow of a dividing Dictyostelium cell and discharged it onto a neighboring cell using a microcapillary. However, the neighboring cells did not show any chemotaxis toward the fluid. In addition, the cells did not manifest an increase in the levels of intracellular Ca2+, cAMP, or cGMP, which are expected to rise in chemotaxing cells. From several lines of our experiments, including these findings, we concluded that chemotaxis does not contribute to cytokinesis D. As an alternative, we propose a cortical-flow model, where a migrating cell attaches to a dividing cell by chance and is guided toward the furrow by the cortical flow on the dividing cell, and then physically assists the separation of the daughter cells.

Dynamin-Like Protein B of Dictyostelium Contributes to Cytokinesis Cooperatively with Other Dynamins.

Dynamin is a large GTPase responsible for diverse cellular processes, such as endocytosis, division of organelles, and cytokinesis. The social amoebozoan, Dictyostelium discoideum, has five dynamin-like proteins: dymA, dymB, dlpA, dlpB, and dlpC. DymA, dlpA, or dlpB-deficient cells exhibited defects in cytokinesis. DlpA and dlpB were found to colocalize at cleavage furrows from the early phase, and dymA localized at the intercellular bridge connecting the two daughter cells, indicating that these dynamins contribute to cytokinesis at distinct dividing stages. Total internal reflection fluorescence microscopy revealed that dlpA and dlpB colocalized at individual dots at the furrow cortex. However, dlpA and dlpB did not colocalize with clathrin, suggesting that they are not involved in clathrin-mediated endocytosis. The fact that dlpA did not localize at the furrow in dlpB null cells and vice versa, as well as other several lines of evidence, suggests that hetero-oligomerization of dlpA and dlpB is required for them to bind to the furrow. The hetero-oligomers directly or indirectly associate with actin filaments, stabilizing them in the contractile rings. Interestingly, dlpA, but not dlpB, accumulated at the phagocytic cups independently of dlpB. Our results suggest that the hetero-oligomers of dlpA and dlpB contribute to cytokinesis cooperatively with dymA.

Systematic literature review of the clinical, humanistic, and economic burden associated with asthma uncontrolled by GINA Steps 4 or 5 treatment.

OBJECTIVE: This study sought to characterize the epidemiologic, clinical, humanistic, and economic burden of patients with asthma uncontrolled by GINA Steps 4 or 5 treatment (severe, uncontrolled asthma [SUA]). METHODS: A systematic literature review adhering to PRISMA guidelines was performed. Relevant publications were searched for in MEDLINE and EMBASE from January 2004 to September 2016 and in a conference proceedings database from January 2012 to October 2016. Studies were screened using the Population, Intervention, Comparator, Outcomes, Study Design, and Time (PICOS-T) framework. Studies of SUA with observational (prospective and retrospective), randomized, or nonrandomized study designs; adult patient populations; sample sizes ≥20 patients; epidemiologic or clinical outcomes, patient-reported outcomes (PROs), or economic outcomes were included. For our analysis, SUA was defined as inadequate control of asthma, despite the use of medium- to high-dosage inhaled corticosteroids and at least one additional treatment. RESULTS: A total of 195 articles reporting unique study populations were included. Prevalence of SUA was as great as 87.4% for patients with severe asthma, although values varied depending on the criteria used to define asthma control. Compared with patients with severe asthma who were controlled, patients with SUA experienced more symptoms, night-time awakenings, rescue medication use, and worse PROs. SUA-associated costs were 3-times greater than costs for patients with severe, controlled disease. CONCLUSION: Despite the availability of approved asthma treatments, this literature analysis confirms that SUA poses a substantial epidemiologic, clinical, humanistic, and economic burden. Published data are limited for certain aspects of SUA, highlighting a need for further research.

Traction force and its regulation during cytokinesis in Dictyostelium cells.

Cytokinesis is the final stage of cell division. Dictyostelium cells have multiple modes of cytokinesis, including cytokinesis A, B and C. Cytokinesis A is a conventional mode, which depends on myosin II in the contractile ring. Myosin II null cells divide depending on substratum-attachment (cytokinesis B) or in a multi-polar fashion independent of the cell cycle (cytokinesis C). We investigated the traction stress exerted by dividing cells in the three different modes using traction force microscopy. In all cases, the traction forces were directed inward from both poles. Interestingly, the traction stress of cytokinesis A was the smallest of the three modes. Latrunculin B, an inhibitor of actin polymerization, completely diminished the traction stress of dividing cells, but blebbistatin, an inhibitor of myosin II ATPase, increased the traction stress. Myosin II is proposed to contribute to the detachment of cell body from the substratum. When the cell-substratum attachment was artificially strengthened by a poly-lysine coating, wild type cells increased their traction stress in contrast to myosin II null and other cytokinesis-deficient mutant cells, which suggests that wild type cells may increase their own power to conduct their cytokinesis. The cytokinesis-deficient mutants frequently divided unequally, whereas wild type cells divided equally. A traction stress imbalance between two daughter halves was correlated with cytokinesis failure. We discuss the regulation of cell shape changes during cell division through mechanosensing.