Peritoneal dialysis-associated infection caused by Mycobacterium abscessus in a pediatric patient on continuous peritoneal dialysis without switching to hemodialysis.

Most peritoneal dialysis (PD)-associated infections caused by Mycobacterium abscessus (M. abscessus) require a transfer from PD to hemodialysis (HD). Here, we report a pediatric case of exit-site and tunnel infections caused by M. abscessus, for whom PD was continued with catheter replacement, debridement of the infected site, and the administration of multiple antibacterial agents. A 10-year-old boy with end-stage kidney disease secondary to juvenile nephronophthisis with NPHP1 deletion, for whom PD was initiated at the age of 9 years, was admitted to the hospital with complaints of fever, pus at the exit-site of the PD catheter, and poor PD drainage. The dialysis effluent culture results were negative; however, M. abscessus was detected in the pus at the exit-site of the PD catheter. The management of HD was expected to be challenging owing to the presence of developmental disorders. Therefore, PD was continued with the simultaneous removal of the PD catheter, reinsertion of a new catheter at a new site, and debridement of the infected site. Multiple antibacterial therapies were administered for 2 months, and the patient was eventually discharged without switching to HD. To the best of our knowledge, this is the first pediatric case of a PD-associated infection caused by M. abscessus, for whom PD was continued without switching to HD. This treatment strategy is not generally recommended but may be an option for patients without peritonitis who have difficulty switching to HD.

Force-sensing treadmill gait analysis system can detect gait abnormalities in haemophilia patients without arthropathy.

BACKGROUND: Joint damage in patients with haemophilia (PwH) is commonly assessed by imaging, but few reports have described how structural changes in joints, for example, haemophilic arthropathy (HA)-affect gait ability. OBJECTIVES: We evaluated gait function among PwH with HA, PwH without HA, and people without haemophilia (non-PwH) using a Zebris FDM-T treadmill (FDM-T), an easy-to-use gait assessment instrument with a force sensor matrix. METHODS: The following gait parameters were collected: centre of pressure trajectory intersection (COPi) anterior/posterior variability, COPi lateral variability, COPi anterior/posterior symmetry, COPi lateral symmetry, single-limb support line (SLSL) length, and SLSL variability. Participants walked at their typical gait speed. The physical function of the PwH was assessed by the Hemophilia Joint Health Score (HJHS). Parameters were compared among the three groups. RESULTS: Twelve PwH with HA, 28 PwH without HA, and 12 non-PwH were enrolled. Gait speed significantly differed between groups (non-PwH, 3.1 ± 0.7; PwH without HA, 2.0 ± 0.7; PwH with HA; 1.5 ± 0.4). The COPi anterior/posterior variability, COPi lateral variability, SLSL length, and SLSL variability were greater in the PwH groups than in the non-PwH group. The COPi lateral symmetry differed between PwH with HA and the other groups. The HJHS was not correlated with gait parameters among PwH with HA. CONCLUSIONS: Gait parameters and speed were abnormal in both PwH with HA and PwH without HA. The FDM-T can be used to identify early stages of physical dysfunction that cannot be detected by conventional functional assessments such as the HJHS.

Reduced plasma factor X is associated with a lack of response to recombinant activated factor VII in patients with hemophilia A and inhibitor, but does not impair emicizumab-driven hemostasis in vitro.

BACKGROUND: The hemostatic effect of recombinant (r) factor (F)VIIa after repetitive intermittent administration may be attenuated in patients with hemophilia A (PwHA) with inhibitors (PwHAwI) creating a clinically unresponsive status, although mechanism(s) remain to be clarified. In patients receiving prophylaxis treatment with emicizumab, concomitant rFVIIa is sometimes utilized in multiple doses for surgical procedures or breakthrough bleeding. AIM AND METHODS: We identified 'unresponsiveness' to rFVIIa, based on global coagulation function monitored using rotational thromboelastometry (ROTEM) in 11 PwHAwI and 5 patients with acquired HA, and investigated possible mechanisms focusing on the association between plasma FX levels and rFVIIa-mediated interactions. RESULTS: Our data demonstrated that FX antigen levels were lower in the rFVIIa-unresponsive group than in the rFVIIa-responsive group (0.46 ± 0.14 IU/mL vs. 0.87 ± 0.15 IU/mL, p < 0.01). This relationship was further examined by thrombin generation assays using a FX-deficient PwHAwI plasma model. The addition of FX with rFVIIa was associated with increased peak thrombin (PeakTh) generation. At low levels of FX (<0.5 IU/mL), rFVIIa failed to increase PeakTh to the normal range, consistent with clinical rFVIIa-unresponsiveness. In the presence of emicizumab (50 µg/mL), PeakTh was increased maximally to 80 % of normal, even at low levels of FX (0.28 IU/mL). CONCLUSIONS: Unresponsiveness to rFVIIa was associated with reduced levels of FX in PwHAwI. Emicizumab exhibited in vitro coagulation potential in the presence of FX at concentrations that appeared to limit the clinical response to rFVIIa therapy.

The effects of emicizumab on in vitro coagulation and fibrinolysis parameters in patients with disseminated intravascular coagulation with and without addition of anti-FVIII antibody.

BACKGROUND: Emicizumab (Emi) is used as haemostatic prophylaxis for patients with haemophilia A (PwHA). Disseminated intravascular coagulation (DIC) is a condition characterized by persistent systemic activation of coagulation, but there is yet no information on coagulation and fibrinolysis potentials in Emi-treated PwHA with DIC. AIM: To examine the effect of Emi on coagulation and fibrinolysis potentials in HA-model DIC plasmas. METHODS: Plasma from a patient with sepsis-DIC (seven patients) was treated with anti-factor (F)VIII monoclonal antibody (HA-model DIC plasma) and incubated with Emi (50 µg/mL). The plasma was then assessed using clot-fibrinolysis waveform analysis (CFWA). Coagulation and fibrinolysis parameters were expressed as ratios relative to normal plasma (|min1|-ratio and |FL-min1|-ratio, respectively). PATIENTS AND RESULTS: In case 1, coagulant potential was slightly high and fibrinolytic potential was extremely low, presenting a coagulant-dominant state (|min1|-ratio/|FL-min1|-ratio: 1.1/.38). In cases 2-5, fibrinolytic potential was not suppressed, but there were marked hypercoagulant potentials, indicating relative coagulant-dominant states. In case 6, coagulant and fibrinolytic potentials were increased but well balanced (|min1|-ratio/|FL-min1|-ratio: 1.38/1.28). In case 7, both potentials were severely deteriorated in not only CFWA but also the thrombin/plasmin generation assay. The addition of Emi into the HA-model DIC plasmas increased |min1|-ratio values in all cases, but the coagulant potentials did not exceed the initial ones (DIC plasma before treatment with anti-FVIII antibody). CONCLUSIONS: The presence of Emi in the HA-model DIC plasma improved coagulation potentials, but did not increase coagulation potentials beyond those of DIC plasma in non-HA states.

Real-world long-term safety and effectiveness of turoctocog alfa in the treatment of haemophilia A in Japan: results from a multicentre, non-interventional, post-marketing study.

OBJECTIVES: To assess the safety and effectiveness of turoctocog alfa in previously treated patients (PTPs) and previously untreated patients (PUPs) with haemophilia A in a real-world setting in Japan. METHODS: This multicentre, non-interventional, post-marketing study recruited patients with haemophilia A who initiated treatment with turoctocog alfa from 18 sites (08/2014-12/2018). The primary endpoint was adverse events (AEs) during the 2-year study period. RESULTS: The safety and effectiveness analysis set included 39 patients. In total, 13 (33.3%) patients reported ≥1 AE; incidence rate was 60.4 events/100 patient-years of exposure (PYE). Treatment was withdrawn in two cases: pruritus in a PTP and factor VIII inhibitor development in a PUP. Inhibitor development occurred in 2.6% of all patients, with an incidence rate of 3.8 events/100 PYE. The rate of inhibitor development was 0%, 25% and 20% in PTPs, PUPs and PUPs with severe type, respectively. The haemostatic success rate was 91.4% for 383 bleeding episodes and 85.7% for 14 surgeries. The negative binomial annualised bleeding rate for the prophylaxis regimen was 6.19 episodes/year (95% CI, 3.69-10.38). The mean (SD) total consumption of turoctocog alfa (n = 34; excluding FVIII inhibitors) was 5,382.6 (7,180.1) IU/kg/year/patient; consumption was 4,133.1 (1,452.4) IU/kg/year/patient for prophylaxis. DISCUSSION: The effectiveness and safety profiles were comparable to those observed in other turoctocog alfa trials; effectiveness analysis and consumption were not affected by treatment regimens. CONCLUSION: Long-term use of turoctocog alfa therapy in clinical practice posed no newly identified safety issues and was effective for prophylaxis and treatment of bleeds in patients with haemophilia A in Japan.

Anticoagulant effects of protein C, protein S, and antithrombin levels on the protein C pathway in young children.

The protein C (PC) pathway involves physiological anticoagulant factors (PC, protein S [PS], and factor V) and performs major anticoagulant functions in adults. Variations in overall PC pathway function due to dynamic changes in PC and PS in early childhood are poorly understood. We aimed to evaluate the contributions of PC pathway function during early childhood by measuring changes in plasma thrombin generation (TG) after administration of the PC activator protac. We evaluated correlations between anticoagulant factors and percentage of protac-induced coagulation inhibition (PiCi%). Before protac addition, TG in newborns (n = 35), infants (n = 42), young children (n = 35), and adults (n = 20) were 525 ± 74, 720 ± 96, 785 ± 53, and 802 ± 64 mOD/min, and PiCi% were 42.1 ± 9.9, 69.8 ± 11.0, 82.9 ± 4.4, and 86.9 ± 3.4%, respectively. The distribution of PiCi% on the two axes of TG (with or without protac) changed continuously with age and differed from that of warfarin-treated plasma and adult PC- or PS-deficient plasma. PiCi% increased dynamically during infancy and correlated with PS levels in newborns and PC levels in young children. Addition of PC or fresh frozen plasma equivalent to approximately 25% PC to PC-deficient plasma improved PiCi%. This automatic measurement requires only a small sample volume and is useful for analysis of developmental hemostasis.

Hybrid human-porcine factor VIII proteins partially escape the inhibitory effects of anti-factor VIII inhibitor alloantibodies having A2 or C2 domain specificity.

INTRODUCTION: Porcine factor (pF)VIII has low cross-reactivity with anti-human (h)FVIII inhibitor alloantibodies. Clinical trials of pFVIII in congenital haemophilia A patients with inhibitor (PwHA-I) are in progress. Most polyclonal anti-hFVIII inhibitors recognize its A2 and/or C2 domain(s), and recombinant human-porcine hybrid (hp)FVIII proteins may escape neutralization by these inhibitors. AIM: To evaluate the ability of hpFVIII to limit the anti-FVIII activity of inhibitor alloantibodies. METHODS: Three hybrid proteins were created by substituting the hFVIII A2, C2 domain or both with the corresponding domains of pFVIII [termed hp(A2), hp(C2) and hp(A2/C2), respectively]. The reactivity of these hybrids was assessed by one-stage clotting assays (OSA), thrombin generation assays (TGA) and rotational thromboelastometry (ROTEM) by adding them to FVIII-deficient samples. RESULTS: OSA demonstrated that the hybrid proteins avoided neutralization by anti-FVIII A2 or C2 monoclonal antibodies (mAb) and polyclonal inhibitor-antibodies (polyAb) from PwHA-I. In TGA, thrombin generation with hp(A2) and hp(A2/C2) was not attenuated in the presence of patient IgG recognizing anti-A2 domain. In contrast, that with hFVIII and hp(C2) was suppressed by this IgG to levels equivalent to those of FVIII-deficient plasma. With anti-A2/C2 polyAb, the activity of hp(A2/C2) was unaffected. ROTEM demonstrated that the addition of hp(A2) or hp(A2/C2) to anti-A2 polyAb shortened clot times/clot formation times, whilst hFVIII or hp(C2) were ineffective. Similarly with anti-A2/C2 polyAb, hp(A2/C2) restored coagulation potential to a greater extent than hp(A2) and hp(C2). CONCLUSION: Hybrid FVIII proteins containing porcine FVIII A2 and/or C2 domain(s) could support effective therapy in PwHA-I by avoiding neutralization.

The clinical and genetic landscape of early-onset thrombophilia in Japan.

OBJECTIVES: To determine the optimal management for early-onset thrombophilia (EOT), the genetic and clinical features of protein C (PC)-, protein S (PS)-, or antithrombin (AT)-deficient patients of ≤20 years of age were studied in Japan. METHODS/RESULTS: Clinical and genetic information of all genetically diagnosed cases was collected through the prospective, retrospective study, and literature review. One-hundred-one patients had PC (n = 55), PS (n = 29), or AT deficiency (n = 18). One overlapping case had PC- and PS-monoallelic variant. Fifty-five PC-deficient patients (54%) had 26 monoallelic or 29 biallelic variant(s), and 29 (29%) PS-deficient patients had 20 monoallelic or nine biallelic variant(s). None of the patients had AT-biallelic variants. The frequent low-risk allele p.K193del (PC-Tottori) was found in five patients with monoallelic (19%) but not 29 with biallelic variant(s). The most common low-risk allele p.K196E (PS-Tokushima) was found in five with monoallelic (25%) and six with biallelic variant(s) (67%). One exceptional de novo PC variant was found in 32 families with EOT. Only five parents had a history of thromboembolism. Thrombosis concurrently developed in three mother-newborn pairs (two PC deficiency and one AT deficiency). The prospective cohort revealed the outcomes of 35 patients: three deaths with PC deficiency and 20 complication-free survivors. Neurological complications were more frequently found in patients with PC-biallelic variants than those with PC-, PS-, or AT-monoallelic variants (73% vs. 24%, p = .019). CONCLUSIONS: We demonstrate the need for elective screening for EOT targeting PC deficiency in Japan. Early prenatal diagnosis of PC deficiency in mother-infant pairs may prevent perinatal thrombosis in them.

NXT007-mediated hemostatic potential is suppressed by activated protein C-catalyzed inactivation of activated factor V.

Background: Activated protein C (APC) inactivates activated factor (F) V (FVa) and FVIIIa. NXT007, an emicizumab-based engineered therapeutic bispecific antibody, enhances the coagulation potential of FVIII-deficient plasma (FVIIIdef-plasma) to near normal levels. However, little is known about the effect of APC-induced inactivation in NXT007-mediated hemostatic function. Objectives: To investigate the contribution of APC-mediated reactions to NXT007-driven hemostasis. Methods: In pooled normal plasma (PNP) or FVIIIdef-plasma spiked with NXT007 (10 µg/mL), effects of APC (0-16 nM) were measured using a thrombin generation assay (TGA). The direct effects of APC on cofactor activity of NXT007 or FVIIIa in a FXa generation assay were also measured. The FVdef-plasma and FV Leiden plasma (FVLeiden plasma) were preincubated with 2 anti-FVIII monoclonal antibodies (termed FVIII-depleted), and the APC effect in the presence of NXT007 in FVIII-depleted FVdef-plasma with the addition of exogenous FV (7.5-30 nM) or FVIII-depleted FVLeiden plasma was investigated. Results: The APC dose-dependent suppression effect in TGA of FVIIIdef-plasma spiked with NXT007 was similar to that of PNP. FXa generation with NXT007 was not impaired by the addition of APC, suggesting that the APC-induced reaction in TGA with NXT007 was attributed to the direct inactivation of FVa. The addition of APC to FVIII-depleted FVdef-plasma, along with NXT007 and various FV concentrations, showed a similar attenuation to PNP. The NXT007-driven thrombin generation in FVIII-depleted FVLeiden plasma was suppressed by APC, similar to the reaction in native FVLeiden plasma. Conclusion: NXT007 did not impair APC-mediated downregulation of FVa in FVIIIdef-plasmas, regardless of the presence of FV mutation with APC resistance.

The role of proteolytic cleavage at Arg336 and Arg372 of the A1 domain in factor VIIa/tissue factor-catalyzed reactions of B domain-deleted factor VIII.

BACKGROUND: We previously demonstrated that factor (F)VIII was rapidly activated through proteolytic cleavage at Arg372 and Arg740 by activated FVII (FVIIa)/tissue factor (TF) in very early coagulation phase, followed by inactivation by cleavage at Arg336. The influence of the absence of FVIII B domain in this series of FVIIa/TF-catalyzed reaction remains unclear, however. AIM: To examine the FVIIa/TF-catalyzed reaction of B domain-deleted (BDD-)FVIII. METHODS AND RESULTS: The FVIII activity (FVIII:C) of commercial full-length (FL-)FVIII and BDD-FVIII increased by ∼1.7-fold within 0.5 min after addition of FVIIa/TF (1 nM/0.1 nM). FVIII: C decreased to initial levels with inactivation rate constant (k; ∼0.035) within 15 min of FL-FVIII activation, but decreased gradually to initial levels (k; ∼0.017) within 30 min of BDD-FVIII activation. SDS-PAGE analyses demonstrated that the FVIIa/TF-catalyzed cleavage of BDD-FVIII occurred at Arg336 within 0.5 min in parallel with elevation of FVIII:C, but cleavage at Arg372 was not evident. FVIIa/TF-catalyzed activation of both recombinant BDD-FVIII R336A and R372A mutants that were prepared, were similar to that of wild-type (WT) BDD-FVIII. However, FVIII:C returned to initial levels (k; ∼0.046) within 30 min of R336A mutant activation, but little reduction of FVIII:C was observed with R372A mutant (k; ∼0.0046). SDS-PAGE analysis indicated that FVIIa/TF-catalyzed cleavage of WT and R372A mutant was predominant at Arg336, whereas that of R336A mutant was observed at Arg372. CONCLUSIONS: FVIIa/TF-catalyzed activation of BDD-FVIII was initiated by cleavage at Arg336, and the FVIII B domain appeared to control FVIIa/TF-catalyzed reactions by altering pattern of cleavage at Arg336 and Arg372.

Association of physical activity with bleeding events and safety in patients with haemophilia A starting emicizumab prophylaxis: an interim analysis of the TSUBASA study.

INTRODUCTION: Little information exists on the relationship between bleeding outcomes and physical activity in patients with haemophilia A (PwHA). AIM: This interim analysis of the TSUBASA study (UMIN-CTR ID: UMIN000037448) evaluated the association of physical activity with bleeding and safety in PwHA starting emicizumab. METHODS: PwHA without factor VIII inhibitors were recruited. Physical activity and bleed data were obtained using an electronic patient-reported outcome application and wearable activity tracker. Adverse events (AEs) were documented. RESULTS: At data cut-off (31-May-2021), 107 PwHA were enrolled, with a median (range) age of 35 (0-73) years. Physical activity data were obtained for 74 participants. Of these, 47 (63.5%) recorded a total of 396 exercise events. The most common exercise events were walking (32.4%), cycling (14.9%), and football (5.4%). Two (0.5%) exercise events in the same individual were associated with bleeding (running, weight training). The safety analysis population consisted of 106 participants treated with emicizumab (median observation period: 241.5 days). Twenty-one (19.8%) participants experienced a total of 39 AEs. Five (4.7%) experienced a serious AE, none of which was emicizumab-related, and three (2.8%) experienced an adverse drug reaction. CONCLUSIONS: PwHA receiving emicizumab in the TSUBASA study experienced minimal bleeding associated with physical activity. TRIAL REGISTRATION: Trial registration: UMIN-CTR ID: UMIN000037448.

Emicizumab-mediated hemostatic function assessed by thrombin generation assay in an in vitro model of factor VIII-depleted thrombophilia plasma.

Patients with hemophilia A (PwHA) may have concurrent deficiency of representative anticoagulant proteins, protein (P)C, PS, and antithrombin (AT), which reduces bleeding frequency. However, emicizumab-driven hemostasis in PwHA with such thrombophilic potential remains unclarified. This study investigated the influence of natural anticoagulants on emicizumab-driven coagulation in HA model plasma. Various concentrations of PS and AT were added to PS-deficient plasma and AT-deficient plasma in the presence of anti-FVIII antibody (FVIIIAb; 10BU/mL). PC-deficient plasma was mixed with normal plasma at various concentrations in the presence of FVIIIAb. Emicizumab (50 µg/mL) was added to these thrombophilic HA model plasmas, prior to tissue factor/ellagic acid-triggered thrombin generation assays. Co-presence of emicizumab increased peak thrombin values (PeakTh) dependent on PS, AT, and PC concentrations. Maximum coagulation potentials in the PS-reduced HA model plasmas remained normal in the presence of emicizumab. PeakTh were close to normal in the presence of 50%AT irrespective of emicizumab, but were higher than normal in the presence of 25%AT. Addition of recombinant FVIIa (corresponding to an administered dose of 90 µg/kg) enhanced coagulation potential to normal levels. Our findings provide novel information on hemostatic regulation in emicizumab-treated PwHA with a possible thrombophilic disposition.

Hemostatic potential of recombinant von Willebrand factor and standard or pegylated extended half-life recombinant factor VIII on thrombus formation under high shear flow.

BACKGROUND: Von Willebrand factor (VWF) and factor VIII (FVIII) complex play a pivotal role in hemostasis. A deficiency or defect of VWF causes von Willebrand disease (VWD). Recombinant (r)VWF product has proved to be effective for hemostatic treatment of VWD, but limited information is available on their role in moderating thrombus formation under flow condition. We aimed to assess thrombus formation in the presence of rVWF combined with rFVIII or pegylated-extended half-life rFVIII (peg-EHL-rFVIII) in VWD whole blood under high shear flow. METHODS: Perfusion chamber experiments under high shear (2,500 s- 1) combined with immunostaining were performed using patient's whole blood with type 1 VWD, mixed with rVWF (Vonvendi®; 1.6 IU/mL), rFVIII or peg-EHL-rFVIII (Advate® or Adynovate®; 1.0 IU/mL), or both. Similar experiments were also conducted with clinical medical devices (T-TAS®). RESULTS: The addition of rFVIII did not augment thrombus formation assessed by surface coverage (SC) and thrombus height (TH), whereas rVWF enhanced these parameters (SC 19.1 ± 1.1% vs. 30.1 ± 4.1%, TH 2.2 ± 0.14 µm vs. 3.6 ± 0.40 µm, respectively). The co-presence of rVWF/rFVIII was comparable to plasma-derived VWF/FVIII (Confact®, VWF:FVIII ratio = 1.6:1.0) for increasing thrombogenicity in SC (32.5 ± 4.3% vs. 38.7 ± 5.5%) and in TH (5.0 ± 0.60 µm vs. 5.5 ± 0.64 µm), respectively. The pre-incubation time with rVWF and rFVIII appeared to have a little effect on the size of thrombus. Peg-EHL-rFVIII mediated thrombus formation to similar extent as rFVIII in the co-presence of rVWF. Similar results were obtained even with T-TAS. Immunostaining demonstrated that rFVIII and peg-EHL-rFVIII were similarly co-localized with rVWF in formed thrombi, indicating that pegylation did not interfere with molecular complexes. CONCLUSION: The effects of high-level rVWF and peg-EHL-rFVIII on thrombus formation were comparable to conventional therapeutic products in a patient's whole blood with VWD under high shear flow.

Single-facility study of the effectiveness of rehabilitation therapy using wearable hybrid assistive limb for patients with bleeding disorders: study protocol for a randomised controlled trial.

INTRODUCTION: Haemophilic arthropathy, a serious complication of haemophilia, results from recurrent joint bleeding, causing progressive joint damage and severely impacting patient quality of life. Rehabilitation therapy (RT) effectively addresses declining physical function due to joint degradation, but pain during RT can hinder its success. Therefore, an effective pain-alleviating treatment method is required. The single-joint hybrid assistive limb (HAL-SJ), a powered exoskeleton, measures bioelectric potential during muscle contraction and provides motorised support, potentially alleviating pain. OBJECTIVE: This study outlines our protocol for a randomised, prospective, single-blind (evaluator) trial aimed to investigate the effects of HAL-SJ on pain reduction during RT, kinesiophobia and other physical functions in patients with haemophilia. METHODS AND ANALYSIS: This two-group comparison intervention study will include 24 male patients aged 12-85 years diagnosed with a bleeding disorder necessitating RT for pain and physical function improvement. The primary outcome measures pain changes during the first and second RT session in patients receiving HAL-SJ-assisted RT compared with traditional RT without HAL-SJ. The secondary outcomes include kinesiophobia (Japanese version of the Tampa Scale for Kinesiophobia), standing position gait (zebris FDM-T treadmill), range of motion (manual goniometer) and body surface temperature (infrared thermography camera) during the study period of up to 3 months or until the end of 10 RTs. RT intensity remains below that required to move the affected joint against gravity, given HAL-SJ's muscular support. The follow-up period extends to 1 month after the last RT. Intergroup study variables are compared by an unpaired t-test or Mann-Whitney test. Intragroup comparisons of secondary outcomes are analysed by a paired t-test or Wilcoxon signed-rank test. ETHICS AND DISSEMINATION: This study was approved by the accreditation committee of Nara Medical University Hospital. The study results will disseminate through publication in a peer-reviewed journal. TRIAL REGISTRATION NUMBER: jRCTs052220076.

Pediatric mesangial proliferative glomerulonephritis has increased the platelet thrombus formation potentials under high-shear flow condition.

INTRODUCTION: Blood coagulation is associated with glomerulonephritis (GN) pathophysiology. Using whole-blood-based rotational thromboelastometry, we recently reported that the degree of hypercoagulability in pediatric patients with immunoglobulin A nephropathy (IgAN), a GN, might be associated with pathological severity. To further clarify the coagulation status of mesangial proliferative glomerulonephritis (MesPGN), we assessed the platelet thrombus formation (PTF) under high-shear flow using a microchip-based flow chamber system (T-TAS®). METHODS: Thirty-four pediatric patients definitively diagnosed with MesPGN by renal biopsy at Nara Medical University Hospital between 2015 and 2022 were enrolled, and 29 patients (case group; median age, 8.0 years) were assessed. Microchips coated with collagen (PL-chip) were used to assess PTF at high-shear in whole blood. The times to increase by 10 and 30 kPa (T10 and T30) from baseline were calculated and compared with those of the pediatric controls. Changes in the parameters during the treatment course and the relationship between pathological severity and the parameters were evaluated. RESULTS: T10 and T30 parameters in the PL-chip were significantly shorter and the area under the curves were greater in the case group than those in the control group (both p <0.05). Each parameter was enhanced during the 3-week treatment but improved after the end of treatment. No significant relationship was observed between pathological severity and these parameters. Little PTF difference was observed between IgAN and Henoch-Schönlein purpura nephritis. CONCLUSIONS: Pediatric MesPGN increased the potential for PTF under high-shear flow conditions.

Longitudinal dynamic changes in factor VIII inhibitor titers in patients with hemophilia A and inhibitors receiving emicizumab prophylaxis.

Emicizumab prophylaxis dramatically reduces bleeding events in patients with hemophilia A (PwHA) with or without factor VIII (FVIII) inhibitors. However, long-term dynamic changes in FVIII inhibitor titers during emicizumab prophylaxis remain to be investigated. We conducted a retrospective follow-up study of FVIII inhibitor titers after initiation of emicizumab prophylaxis in 25 PwHA carrying current or historical FVIII inhibitors. Nineteen PwHA had FVIII inhibitors at initiation of emicizumab prophylaxis (age: median 22 [range 4-60] years and inhibitor titer: 30 [1.0-1450] BU/mL). In 17 of the 19 patients, the inhibitor titers markedly decreased to a median of 1.2 (< 0.6-58) BU/mL at a median follow-up of 71 (38-111) months. In two patients, titers were slightly elevated after initiation of emicizumab but decreased in the long term. The remaining six patients had negative inhibitor status (< 0.6 BU/mL) when switched to emicizumab from FVIII prophylaxis. Five patients maintained negative titers. One patient had inhibitor recurrence, with a peak titer of 1.6 BU/mL that decreased to 0.9 BU/mL. In most cases, FVIII inhibitor titers can be expected to decrease spontaneously during emicizumab prophylaxis, but regular follow-up is necessary to manage breakthrough bleeds.

The in vitro effect of anticoagulant agents on coagulation and fibrinolysis in the presence of emicizumab in the plasmas from patients with haemophilia A.

INTRODUCTION: Emicizumab is used as hemostatic prophylaxis for patients with hemophilia A (PwHA), irrespective of the presence of inhibitors. Although bacterial infection can lead to a procoagulant state, there is limited information on coagulation and fibrinolysis potentials in emicizumab-treated PwHA and on the use of anticoagulants in such cases. AIM: We examined whether anticoagulants affect the coagulation and fibrinolysis potentials in plasma from PwHA spiked with emicizumab. METHODS: Plasma from PwHA was in vitro supplemented with emicizumab (50 µg/mL; emi-plasma) and anticoagulants (recombinant thrombomodulin (rTM), nafamostat mesylate (NM), unfractionated heparin (UFH), or low-molecular-weight heparin (LMH)). PwHA plasma spiked with rFVIII (1 IU/mL) was used as a reference (ref-plasma). The coagulation and fibrinolysis potentials in plasma was measured by thrombin and plasmin generation assay (T/P-GA) and clot-fibrinolysis waveform analysis (CFWA). RESULTS: In T/P-GA and CFWA, coagulation potentials (maximum coagulation velocity; |min1|, and peak thrombin; Th-Peak) in plasma rose with increasing concentrations of emicizumab and rFVIII, but fibrinolytic potentials (peak plasmin; Plm-Peak, and maximum fibrinolytic velocity; |FL-min1|) remained unchanged. Adding rTM, NM, and UFH to emi-plasma suppressed coagulation and fibrinolysis potentials, similar to ref-plasma. Regarding the heparin, UFH and LMH inhibited the improved coagulation in emi-plasma. UFH inhibited fibrinolysis as well, but LMH did not. CONCLUSIONS: Anticoagulants could exhibit the inhibitory effects on the coagulation and fibrinolysis potentials in plasma from PwHA spiked with emicizumab, similar to those in normal plasma.