The effects of selective beta-adrenergic blockade on bone marrow dysfunction following severe trauma and chronic stress

GPC-100, a novel CXCR4 antagonist, improves in vivo hematopoietic cell mobilization when combined with propranolol

Autologous Stem Cell Transplant (ASCT) is increasingly used to treat hematological malignancies. A key requisite for ASCT is mobilization of hematopoietic stem cells into peripheral blood, where they are collected by apheresis and stored for later transplantation. However, success is often hindered by poor mobilization due to factors including prior treatments. The combination of G-CSF and GPC-100, a small molecule antagonist of CXCR4, showed potential in a multiple myeloma clinical trial for sufficient and rapid collection of CD34+ stem cells, compared to the historical results from the standards of care, G-CSF alone or G-CSF with plerixafor, also a CXCR4 antagonist. In the present study, we show that GPC-100 has high affinity towards the chemokine receptor CXCR4, and it potently inhibits β-arrestin recruitment, calcium flux and cell migration mediated by its ligand CXCL12. Proximity Ligation Assay revealed that in native cell systems with endogenous receptor expression, CXCR4 co-localizes with the beta-2 adrenergic receptor (β2AR). Co-treatment with CXCL12 and the β2AR agonist epinephrine synergistically increases β-arrestin recruitment to CXCR4 and calcium flux. This increase is blocked by the co-treatment with GPC-100 and propranolol, a non-selective beta-adrenergic blocker, indicating a functional synergy. In mice, GPC-100 mobilized more white blood cells into peripheral blood compared to plerixafor. GPC-100 induced mobilization was further amplified by propranolol pretreatment and was comparable to mobilization by G-CSF. Addition of propranolol to the G-CSF and GPC-100 combination resulted in greater stem cell mobilization than the G-CSF and plerixafor combination. Together, our studies suggest that the combination of GPC-100 and propranolol is a novel strategy for stem cell mobilization and support the current clinical trial in multiple myeloma registered as NCT05561751 at www.clinicaltrials.gov.

The treatment of chronic anemia in heart failure: a global approach

Chronic anemia is an independent risk factor for mortality in patients with heart failure (HF). Restoring physiological hemoglobin (Hb) levels is essential to increase oxygen transport capacity to tissues and improve cell metabolism as well as physical and cardiac performance. Nutritional deficits and iron deficiency are the major causes of chronic anemia, but other etiologies include chronic kidney disease, inflammatory processes, and unexplained anemia. Hormonal therapy, including erythropoietin (EPO) and anabolic treatment in chronic anemia HF patients, may contribute to improving Hb levels and clinical outcomes. Although preliminary studies showed a beneficial effect of EPO therapy on cardiac efficiency and in HF, more recent studies have not confirmed this positive impact of EPO, alluding to its side effect profile. Physical exercise significantly increases Hb levels and the response of anemia to treatment. In malnourished patients and chronic inflammatory processes, low levels of anabolic hormones, such as testosterone and insulin-like growth factor-1, contribute to the development of chronic anemia. This paper aims to review the effect of nutrition, EPO, anabolic hormones, standard HF treatments, and exercise as regulatory mechanisms of chronic anemia and their cardiovascular consequences in patients with HF.

Adrenergic Modulation of Erythropoiesis After Trauma

Severe traumatic injury results in a cascade of systemic changes which negatively affect normal erythropoiesis. Immediately after injury, acute blood loss leads to anemia, however, patients can remain anemic for as long as 6 months after injury. Research on the underlying mechanisms of such alterations of erythropoiesis after trauma has focused on the prolonged hypercatecholaminemia seen after trauma. Supraphysiologic elevation of catecholamines leads to an inhibitive effect on erythropoiesis. There is evidence to show that alleviation of the neuroendocrine stress response following trauma reduces these inhibitory effects. Both beta blockade and alpha-2 adrenergic receptor stimulation have demonstrated increased growth of hematopoietic progenitor cells as well as increased pro-erythropoietic cytokines after trauma. This review will describe prior research on the neuroendocrine stress response after trauma and its consequences on erythropoiesis, which offer insight into underlying mechanisms of prolonged anemia postinjury. We will then discuss the beneficial effects of adrenergic modulation to improve erythropoiesis following injury and propose future directions for the field.

Prolonged Chronic Stress and Persistent Iron Dysregulation Prevent Anemia Recovery Following Trauma

Introduction Following major trauma, persistent injury-associated anemia is associated with organ failure, increased length of stay and mortality. We hypothesize that prolonged adrenergic stimulation following trauma is directly responsible for persistent iron dysfunction that impairs anemia recovery. Materials and Methods Naïve rodents, lung contusion and hemorrhagic shock followed by daily handling for 13 d (LCHS), LCHS followed by 6 d of restraint stress and 7 d of daily handling (LCHS/CS-7) and LCHS/CS followed by 13 d of restraint stress with day and/or night disruption (LCHS/CS-14) were sacrificed on day 14. Hemoglobin, plasma, urine, bone marrow/liver inflammatory and erythropoietic markers were analyzed. Results LCHS/CS-14 led to a significant decline in weight gain and persistently elevated plasma and urine inflammatory markers. Liver IL-6, IL-1β and hepcidin expression were significantly increased following LCHS/CS-14. LCHS/CS-14 also had impaired anemia recovery with reduced plasma transferrin and erythropoietin receptor expression. Conclusion Prolonged chronic stress following trauma/hemorrhagic shock led to sustained inflammation with increased expression of IL-1β, IL-6 and hepcidin with decreased iron availability for uptake into erythroid progenitor cells and a lack of anemia recovery.