Derangement of protein S and C4b-binding protein levels as acquired thrombophilia in HIV-infected adult Nigerians

Methods, precision, and analytical sensitivity of a novel low-plasma-volume assay of fibrinolytic capacity utilizing the euglobulin fraction

INTRODUCTION

Fibrinolysis is a critical aspect of the hemostatic system, with assessment of fibrinolytic potential being critical to predict bleeding and clotting risk. We describe the method for a novel low-plasma-volume assay of fibrinolytic capacity utilizing the euglobulin fraction (the "modified mini-euglobulin clot lysis assay [ECLA]"), its analytic sensitivity to alterations in key fibrinolytic substrates/regulators, and its initial applications in acute and convalescent disease cohorts.

METHODS

The modified mini-ECLA requires 50 μL of plasma, a maximal read time of 3 h (with most results available within 60 min), and is entirely performed in a 96-well microplate. Assay measurements were obtained in a variety of commercial control and deficient plasmas representing clinically relevant hypo- and hyperfibrinolytic states, and in three distinct adolescent cohorts with acute or convalescent illness: critically ill, following endotracheal intubation; acute COVID-19-related illness; and ambulatory, 3 months following a venous thromboembolic event.

RESULTS

In 100% and 75% deficient plasmas, hypofibrinolysis for plasminogen-deficient, fibrinolysis for alpha-2-antiplasmin-deficient, and hyperfibrinolysis for plasminogen activator inhibitor-1-deficient plasmas were observed.

CONCLUSION

The modified mini-ECLA Clot Lysis Time Ratio ("CLTR") demonstrated moderate-strength correlations with the Clot Formation and Lysis (CloFAL) assay, is analytically sensitive to altered fibrinolytic states in vitro, and correlates with clinical outcomes in preliminarily-studied patient populations.

HIV, asymptomatic STI, and the rectal mucosal immune environment among young men who have sex with men

Young men who have sex with men (YMSM) are disproportionately affected by HIV and bacterial sexually transmitted infections (STI) including gonorrhea, chlamydia, and syphilis; yet research into the immunologic effects of these infections is typically pursued in siloes. Here, we employed a syndemic approach to understand potential interactions of these infections on the rectal mucosal immune environment among YMSM. We enrolled YMSM aged 18-29 years with and without HIV and/or asymptomatic bacterial STI and collected blood, rectal secretions, and rectal tissue biopsies. YMSM with HIV were on suppressive antiretroviral therapy (ART) with preserved blood CD4 cell counts. We defined 7 innate and 19 adaptive immune cell subsets by flow cytometry, the rectal mucosal transcriptome by RNAseq, and the rectal mucosal microbiome by 16S rRNA sequencing and examined the effects of HIV and STI and their interactions. We measured tissue HIV RNA viral loads among YMSM with HIV and HIV replication in rectal explant challenge experiments among YMSM without HIV. HIV, but not asymptomatic STI, was associated with profound alterations in the cellular composition of the rectal mucosa. We did not detect a difference in the microbiome composition associated with HIV, but asymptomatic bacterial STI was associated with a higher probability of presence of potentially pathogenic taxa. When examining the rectal mucosal transcriptome, there was evidence of statistical interaction; asymptomatic bacterial STI was associated with upregulation of numerous inflammatory genes and enrichment for immune response pathways among YMSM with HIV, but not YMSM without HIV. Asymptomatic bacterial STI was not associated with differences in tissue HIV RNA viral loads or in HIV replication in explant challenge experiments. Our results suggest that asymptomatic bacterial STI may contribute to inflammation particularly among YMSM with HIV, and that future research should examine potential harms and interventions to reduce the health impact of these syndemic infections.

Pregnancy Related Venous Thromboembolism-Associated with HIV Infection and Antiretroviral Therapy

Human immunodeficiency virus (HIV) infection in pregnancy is associated with substantial morbidity and mortality. Improved access to effective antiretroviral therapy (ART) has shifted the spectrum of pregnancy-related complications among HIV-infected pregnant women. In addition to placental vascular complications and preterm delivery, increased rates of venous thromboembolism (VTE) have been described. HIV infection is characterized by immune activation, inflammation, and endothelial dysfunction, which contribute to the activation of coagulation and its prothrombotic consequences. Indeed, activated coagulation factors have been reported to be increased and natural anticoagulants reduced in HIV. Several mechanisms for this persistent prothrombotic balance on ART have been identified. These may include: co-infections, immune recovery, and loss of the gastrointestinal mucosal integrity with microbial translocation. In addition to the direct effects of HIV and ART, traditional venous and obstetric risk factors also contribute to the risk of VTE. A research priority has been to understand the mechanisms of VTE in HIV-infected pregnant women receiving suppressive ART and to translate this into HIV-specific thromboprophylaxis recommendations. Management requires a multidisciplinary approach and further studies are indicated to guide the prevention and management of pregnancy-associated VTE in this population. The current review describes the epidemiology, mechanisms, and management of VTE in HIV-infected women in pregnancy and the postpartum period.

Dysregulation of Protein S in COVID-19

Coronavirus Disease 2019 (COVID-19) has been widely associated with increased thrombotic risk, with many different proposed mechanisms. One such mechanism is acquired deficiency of protein S (PS), a plasma protein that regulates coagulation and inflammatory processes, including complement activation and efferocytosis. Acquired PS deficiency is common in patients with severe viral infections and has been reported in multiple studies of COVID-19. This deficiency may be caused by consumption, degradation, or clearance of the protein, by decreased synthesis, or by binding of PS to other plasma proteins, which block its anticoagulant activity. Here, we review the functions of PS, the evidence of acquired PS deficiency in COVID-19 patients, the potential mechanisms of PS deficiency, and the evidence that those mechanisms may be occurring in COVID-19.

Resolution of possible acquired protein S deficiency after viral suppression in HIV infection

Current literature suggests an increased risk of venous thromboembolism (VTE) in people living with HIV (PLWH) with poorly controlled viraemia and immunodeficiency. VTE treatment guidelines do not specifically address anticoagulation management in PLWH. We report a case of a 33-year-old woman diagnosed with an unprovoked pulmonary embolism (PE) and deemed protein S deficient. Three years later, she was diagnosed with AIDS. Antiretroviral therapy (ART) was promptly initiated with viral suppression and immune reconstitution within 12 months. Eight years after her initial PE, the patient self-discontinued warfarin. Multiple repeat protein S values were normal. ART without anticoagulation has continued for 3 years with no thrombotic events. This case describes a patient with VTE presumably secondary to undiagnosed HIV with possible consequent acquired protein S deficiency. Additional research is needed to understand the characteristics of PLWH with VTE who may warrant long-term anticoagulation as opposed to shorter courses.