Hemophilia A combined with acute myocardial infarction (AMI) is rare and challenging to treat. This article reports a 65-year-old patient with hemophilia A admitted for acute inferior ST-segment elevation myocardial infarction, who successfully underwent emergency drug-coated balloon (DCB) angioplasty with factor VIII replacement support. Dual antiplatelet therapy (DAPT) was discontinued 3 weeks after the operation, after which the patient received neither antithrombotic therapy nor replacement therapy, while comprehensive risk factor control was intensified. No recurrent thrombotic or hemorrhagic events were observed during the 1-year follow-up. This case suggests that the DCB strategy can shorten the required duration of antithrombotic treatment, and discontinuing antithrombotic and replacement therapies may be safe for selected patients, with comprehensive risk factor control serving as the core antithrombotic intervention at this stage.

Anthracycline-induced cardiotoxicity remains a major limitation of cancer therapy, and effective preventive strategies are lacking. Topoisomerase IIb has been implicated as a central driver of this toxicity, suggesting that epigenetic regulators may interfere with the pathological cardiac response. Here, we show that doxorubicin promotes topoisomerase IIb accumulation at cardiomyocyte-specific gene promoters (e.g., Actc1, Myl2, and Myh7) overlapping myocyte enhancer factor 2 binding sites and enhances myocyte enhancer factor 2 -dependent transcription. This response is attenuated by the pan-histone deacetylase inhibitor suberoylanilide hydroxamic acid. Suberoylanilide hydroxamic acid -mediated cardioprotection requires class IIa histone deacetylases, as genetic loss of HDAC4 abolishes its effect. Mechanistically, suberoylanilide hydroxamic acid induces acetylation of the chaperone 14-3-3, disrupting its interaction with HDAC4/5, promoting their nuclear accumulation, and repressing myocyte enhancer factor 2 - driven transcription. In vivo, suberoylanilide hydroxamic acid mitigates doxorubicin-induced cardiotoxicity. These findings identify histone deacetylase inhibition as a cardioprotective repurposing strategy and reveal a mechanistic link between epigenetic regulation and anthracycline-associated cardiotoxicity.

Phosphatidylserine on the surface of activated cells serves as a signal for coagulation factor binding and the membrane-dependent assembly of enzyme complexes that drive the accelerated host response to vascular damage. Here, we use single-particle cryo-EM of liposome-bound proteins to establish common mechanisms utilized by coagulation factors V and VIII for membrane binding and phospholipid specificity. The interface between these peripheral proteins and the membrane shows contacts between the discoidin C1 and C2 domains and the interfacial phospholipid headgroup region of the membrane bilayer. There is no evidence for the insertion of membrane-contacting protein loops into the membrane core. This refutes previous models of high affinity protein binding by insertion into the hydrophobic core of the membrane. We also resolve density for the headgroup of phosphatidylserine bound to conserved pockets within the C1 and C2 domains. These single binding pockets in each C domain highlight the network of putative hydrogen bonds that contribute to binding specificity for phosphatidylserine. Our results now provide a high-resolution structural view of the protein-membrane interface for these coagulation proteins and highlight the utility of using liposomes as near-physiologic membrane mimetics in structural studies. The principles established in this work may also apply to other biological systems wherein function is regulated by reversible membrane binding.

The formation of factor VIII (FVIII) inhibitors in hemophilia A patients involves complex immune responses, including the activation of CD4 T cells and B cells. Marginal zone (MZ) B cells, an innate-like B cell population in the spleen, play a key role in the early stages of inhibitor development by rapidly responding to blood-borne antigens. These cells are uniquely positioned to capture and present FVIII to CD4 T cells, initiating a robust immune response that can lead to the formation of neutralizing antibodies. This chapter explores the critical role of MZ B cells in FVIII inhibitor development, focusing on their function in antigen presentation and their potential as therapeutic targets to prevent inhibitor formation. Using immunohistochemistry (IHC) and flow cytometry, we investigate the interactions between MZ B cells, CD4 T cells, and other immune components in the spleen, providing a deeper understanding of the molecular mechanisms underlying FVIII inhibitor development. By elucidating these immune interactions, we aim to inform the development of novel strategies to mitigate FVIII inhibitor formation in hemophilia A patients.

To elucidate how a functional disulfide bond controls protein activity, it is essential that the redox state of the bond in the population of protein molecules is known. A differential cysteine alkylation and mass spectrometry technique is described that affords precise quantification of protein disulfide bond redox state. The utility of the technique is demonstrated by quantifying the redox states of the eight disulfide bonds in human coagulation factor VIII.

Disulfide bonds form as proteins fold in the cell and formation was assumed to be complete when the mature protein emerges. This is not the situation for many proteins that are constitutively produced as multiple partially disulfide-bonded states. For some proteins, thousands of different states are predicted assuming no dependencies on disulfide bond formation. In this chapter, probabilities for disulfide bond formation are employed to estimate the number of disulfide-bonded states. Situations where disulfide bond formation is independent of, or dependent on, the state of other bonds in the protein are considered. Estimates of the number of disulfide-bonded protein states will assist with the conceptual and experimental challenges of studying this biology.

The expression of extracellular matrix protein domains, which exhibit biological activities of their own, is required in order to get a sufficient amount to perform experiments aiming at determining their structure, interactions, and functions, and for preclinical and clinical studies. We describe here the protocol we designed to express in human embryonic kidney cells a recombinant von Willebrand factor A domain of human collagen VI, and recombinant anti-angiogenic matrikines of human collagens VIII (vastatin) and XVIII (endostatin).

Acquired haemophilia A (AHA) is a rare but potentially life-threatening autoimmune bleeding disorder caused by autoantibodies against factor VIII. Its presentation is often non-specific and can mimic more common causes of bleeding, leading to delayed diagnosis, particularly in elderly patients. We report the case of a 93-year-old man with multiple comorbidities who presented with spontaneous, extensive bruising and haemorrhagic complications. Laboratory evaluation demonstrated findings consistent with AHA, including isolated prolongation of the activated partial thromboplastin time (aPTT), reduced factor VIII activity, and the presence of factor VIII inhibitors. The patient received haematology-directed treatment; however, his clinical course was complicated, and he ultimately died. This case highlights the importance of maintaining a high index of suspicion for AHA in elderly patients presenting with unexplained bleeding and emphasises the need for prompt diagnosis and early multidisciplinary management.