Persistent injury-associated anemia: the role of the bone marrow microenvironment

Profiling the Expression of Circulating Acute-Phase Proteins, Cytokines, and Checkpoint Proteins in Patients with Severe Trauma: A Pilot Study

Purpose

Severe trauma may lead to the systemic release of inflammatory mediators into the circulation with profound acute-phase responses; however, the understanding of the expression of these mediators remains limited. This study aimed to characterize the alterations in the expression of circulating acute-phase proteins, cytokines, and checkpoint proteins in patients with severe trauma injuries.

Patients and Methods

The study population included trauma patients in the intensive care unit (ICU) with an injury severity score equal to or greater than 16 and who had used a ventilator for 48 hours. A total of 12 female and 28 male patients were recruited for the study; six patients died and 34 survived. Blood samples collected at acute stages were compared with those drawn at the subacute stage, the time when the patients were discharged from the ICU, or before the discharge of the patients from the hospital.

Results

The study identified that the expression of acute-phase proteins, such as alpha-1-acid glycoprotein and C-reactive protein, and cytokines, including granulocyte colony-stimulating factor, interleukin-6, and interleukin-1 receptor antagonist, was elevated in the circulation after severe trauma. In contrast, the levels of acute-phase proteins, such as alpha-2-macroglobulin, serum amyloid P, and von Willebrand factor, and cytokines, including interleukin-4 and interferon gamma-induced protein 10, were reduced. However, there were no significant differences in the expression of checkpoint proteins in the circulation.

Conclusion

The dysregulated proteins identified in this study may serve as potential therapeutic targets or biomarkers for treating patients with severe trauma. However, the related biological functions of these dysregulated factors require further investigation to validate their functions.

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.

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

INTRODUCTION

Propranolol has been shown to improve erythroid progenitor cell growth and anemia following trauma and this study sought to investigate the mechanisms involved by evaluating the effects of selective beta blockade.

METHODS

Male Sprague-Dawley rats were subjected to lung contusion, hemorrhagic shock and chronic stress (LCHS/CS) ± daily selective beta-1, beta-2, or beta-3 blockade (B1B, B2B, B3B). Bone marrow cellularity and growth of erythroid progenitor colonies, hemoglobin, plasma granulocyte colony-stimulating factor (G-CSF), hematopoietic progenitor cell mobilization, and daily weight were assessed.

RESULTS

Selective beta-2 and beta-3 blockade improved bone marrow cellularity, erythroid progenitor colony growth and hemoglobin levels, while decreasing plasma G-CSF, progenitor cell mobilization and weight loss following LCHS/CS.

CONCLUSIONS

Attenuating the neuroendocrine stress response with the use of selective beta-2 and 3 adrenergic blockade may be an alternative to improve bone marrow erythroid function following trauma.

Effect of Beta-Blockade on the Expression of Regulatory MicroRNA after Severe Trauma and Chronic Stress

BACKGROUND

Beta-blockade administration after lung contusion, hemorrhagic shock, and chronic stress has been shown to improve bone marrow function, decrease hypercatecholaminemia, and reduce inflammation. MicroRNAs (miR) are critical biologic regulators that can downregulate gene expression by causing messenger RNA degradation or inhibition of translation. This study sought to expand our understanding of the molecular mechanisms underlying the reduced inflammatory response after the administration of beta-blockade (BB) in our rodent trauma model.

STUDY DESIGN

Male Sprague-Dawley rats aged 8 to 9 weeks were randomized to lung contusion, hemorrhagic shock with daily restraint stress (LCHS/CS) or LCHS/CS plus propranolol (LCHS/CS+BB). Restraint stress occurred 2 hours daily after LCHS. Propranolol (10 mg/kg) was given daily until day 7. Total RNA and miR were isolated from bone marrow and genome-wide miR expression patterns were assayed. Bone marrow cytokine expression was determined with quantitative polymerase chain reaction.

RESULTS

LCHS/CS led to significantly increased bone marrow expression of interleukin (IL) 1β, tumor necrosis factor-α, IL-6, nitric oxide, and plasma C-reactive protein. There were marked differences in expression of 45 miRs in the LCHS/CS+BB group compared with the LCHS/CS group when using a p value <0.001. Rno-miR-27a and miR-25 were upregulated 7- to 8-fold in the rodents who underwent LCHS/CS+BB compared with LCHS/CS alone, and this correlated with reduced bone marrow expression of IL-1β, tumor necrosis factor-α, IL-6, nitric oxide, and reduced plasma C-reactive protein in the LCHS/CS+BB group.

CONCLUSIONS

The genomic and miR expression patterns in bone marrow after LCHS/CS differed significantly compared with rodents that received propranolol after LCHS/CS. The use of BB after severe trauma can help mitigate persistent inflammation by upregulating Rno-miR-27a and miR-25 and reducing inflammatory cytokines in those who remain critically ill.

Flow Cytometric Analysis of Hematopoietic Populations in Rat Bone Marrow. Impact of Trauma and Hemorrhagic Shock

Severe injury and hemorrhagic shock (HS) result in multiple changes to hematopoietic differentiation, which contribute to the development of immunosuppression and multiple organ failure (MOF). Understanding the changes that take place during the acute injury phase may help predict which patients will develop MOF and provide potential targets for therapy. Obtaining bone marrow from humans during the acute injury phase is difficult so published data are largely derived from peripheral blood samples, which infer bone marrow changes that reflect the sustained inflammatory response. This preliminary and opportunistic study investigated leucopoietic changes in rat bone marrow 6 h following traumatic injury and HS. Terminally anesthetized male Porton Wistar rats were allocated randomly to receive a sham operation (cannulation with no injury) or femoral fracture and HS. Bone marrow cells were flushed from rat femurs and immunophenotypically stained with specific antibody panels for lymphoid (CD45R, CD127, CD90, and IgM) or myeloid (CD11b, CD45, and RP-1) lineages. Subsequently, cell populations were fluorescence-activated cell sorted for morphological assessment. Stage-specific cell populations were identified using a limited number of antibodies, and leucopoietic changes were determined 6 h following trauma and HS. Myeloid subpopulations could be identified by varying levels CD11b expression, CD45, and RP-1. Trauma and HS resulted in a significant reduction in total CD11b + myeloid cells including both immature (RP-1(-)) and mature (RP-1+) granulocytes. Multiple B-cell lymphoid subsets were identified. The total percentage of CD90+ subsets remained unchanged following trauma and HS, but there was a reduction in the numbers of maturing CD90(-) cells suggesting movement into the periphery. © 2019 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of International Society for Advancement of Cytometry.

Chronic stress induces persistent low-grade inflammation

INTRODUCTION

This study sought to determine if the systemic cytokine profile of rodents subjected to chronic restraint stress leads to persistent low-grade inflammation.

METHODS

Male Sprague-Dawley rats were subjected to restraint stress for a total of seven or fourteen days. Urine norepinephrine (NE), plasma interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), C-reactive protein (CRP) were assessed with ELISA. Liver expression of IL-6 and TNF-α were assessed with real time PCR.

RESULTS

Chronic stress at 7 and 14 days sequentially increased plasma acute phase reactants (NE, IL-6, TNF-α, and CRP), liver IL-6 expression, hematopoietic progenitor cell mobilization, and decreased erythroid progenitor colony growth. Weight gain was reduced by chronic stress compared to each models' naïve counterpart.

CONCLUSIONS

Combining this model with trauma and sepsis models will allow evaluation of the contribution of persistent inflammation in disease progression and outcomes.

Systemic Regulation of Bone Marrow Stromal Cytokines After Severe Trauma

BACKGROUND

Traumatic injury generates a prolonged hypercatecholamine state that is associated with reduced growth of bone marrow erythroid progenitors mediated by the bone marrow stroma. The bone marrow stroma is made up of many cells including fibroblasts, which respond to inflammatory stimuli and alter the cytokine profile. We hypothesized that trauma plasma would increase bone marrow stromal fibroblast expression of interleukin-6 (IL-6), granulocyte colony-stimulating factor (G-CSF), erythropoietin (EPO), stem cell factor (SCF), and activation of nuclear factor kappa-light-chain-enhancer of activated B cells and correlate with injury severity and anemia.

MATERIALS AND METHODS

Plasma from 15 trauma patients was cultured with bone marrow fibroblast cells and compared with that from healthy volunteers. At 6, 24, and 48 h, the expression of IL-6, G-CSF, EPO, SCF, and the activation of nuclear factor kappa-light-chain-enhancer of activated B cells were measured using quantitative polymerase chain reaction. The influence of trauma plasma on cytokine expression was further stratified by injury severity score (ISS).

RESULTS

The average hemoglobin significantly decreased from admission to discharge (10.7 ± 2.5 to 9.2 ± 1.1 g/dL, P < 0.04). The discharge hemoglobin significantly decreased by 14% from the admission hemoglobin. After 48 h, trauma plasma significantly increased IL-6, G-CSF, and EPO bone marrow fibroblast expression when compared with normal plasma. When stratified by ISS, IL-6, G-CSF, and EPO, bone marrow fibroblast expression was highest in the trauma plasma ISS 27-41 group and was significantly elevated compared with normal plasma. When SCF expression was stratified by ISS, there was a significant increase in expression in ISS 27-41. Higher ISS was also associated with a larger decrease in hemoglobin despite no difference in total blood transfusions.

CONCLUSIONS

Severe trauma can systemically increase IL-6, G-CSF, and EPO expression in bone marrow stroma. Increased hematopoietic cytokine expression after traumatic injury correlated with a hypercatecholamine state, anemia, and injury severity.

The effects of propranolol and clonidine on bone marrow expression of hematopoietic cytokines following trauma and chronic stress

BACKGROUND

Attenuating post-injury neuroendocrine stress abrogates persistent injury-associated anemia. Our objective was to examine the mechanisms by which propranolol and clonidine modulate this process. We hypothesized that propranolol and clonidine would decrease bone marrow expression of high-mobility group box-1 (HMGB1) and increase expression of stem cell factor (SCF) and B-cell lymphoma-extra large (Bcl-xL).

METHODS

Male Sprague-Dawley rats were allocated to naïve control, lung contusion followed by hemorrhagic shock (LCHS), or LCHS plus daily chronic restraint stress (LCHS/CS) ±propranolol, ±clonidine. Day seven bone marrow expression of HMGB1, SCF, and Bcl-xL was assessed by polymerase chain reaction.

RESULTS

Following LCHS, HMGB1 was decreased by propranolol (49% decrease, p = 0.012) and clonidine (54% decrease, p < 0.010). SCF was decreased following LCHS/CS, and was increased by propranolol (629% increase, p < 0.001) and clonidine (468% increase, p < 0.001). Bcl-xL was decreased following LCHS/CS, and was increased by propranolol (59% increase, p = 0.006) and clonidine (77% increase, p < 0.001).

CONCLUSIONS

Following severe trauma, propranolol and clonidine abrogate persistent injury-associated anemia by modulating bone marrow cytokines, favoring effective erythropoiesis.