Macrophage migration inhibitory factor levels correlate with an infection in trauma patients

Inhibition of Macrophage Migration Inhibitory Factor Activity Attenuates Haemorrhagic Shock-Induced Multiple Organ Dysfunction in Rats

Objective

The aim of this study was to investigate (a) macrophage migration inhibitory factor (MIF) levels in polytrauma patients and rats after haemorrhagic shock (HS), (b) the potential of the MIF inhibitor ISO-1 to reduce multiple organ dysfunction syndrome (MODS) in acute (short-term and long-term follow-up) HS rat models and (c) whether treatment with ISO-1 attenuates NF-κB and NLRP3 activation in HS.

Background

The MODS caused by an excessive systemic inflammatory response following trauma is associated with a high morbidity and mortality. MIF is a pleiotropic cytokine which can modulate the inflammatory response, however, its role in trauma is unknown.

Methods

The MIF levels in plasma of polytrauma patients and serum of rats with HS were measured by ELISA. Acute HS rat models were performed to determine the influence of ISO-1 on MODS. The activation of NF-κB and NLRP3 pathways were analysed by western blot in the kidney and liver.

Results

We demonstrated that (a) MIF levels are increased in polytrauma patients on arrival to the emergency room and in rats after HS, (b) HS caused organ injury and/or dysfunction and hypotension (post-resuscitation) in rats, while (c) treatment of HS-rats with ISO-1 attenuated the organ injury and dysfunction in acute HS models and (d) reduced the activation of NF-κB and NLRP3 pathways in the kidney and liver.

Conclusion

Our results point to a role of MIF in the pathophysiology of trauma-induced organ injury and dysfunction and indicate that MIF inhibitors may be used as a potential therapeutic approach for MODS after trauma and/or haemorrhage.

Antishock Characteristics of Erythrocyte-mediated Endoplasmic Reticulum Stress in Macrophages in Severe Hemorrhagic Shock Environment Based on TLR9-cGAS-STING-IFN Signal Axis

This study aimed to investigate the protective effects of erythrocyte-mediated endoplasmic reticulum (ER) stress in macrophages in hemorrhagic shock. An hemorrhagic shock model was established in male BALB/c mice. Animals were randomly divided into three groups (n = 8): control group (A), erythrocyte reinfusion group (B), and TLR9 inhibition group (C). Eight healthy BALB/c mice were also included as group N (n = 8). Mice in group A were not treated, while mice in groups B and C were transfused with red blood cells separated from the blood of mice in group N. Flow cytometry was used to detect the expression of erythrocyte surface protein TLR9 in each group. Immunofluorescence assay was used to analyze the distribution and relative expression of protein STING in macrophages. Flow cytometry was used to analyze the expression of STING, ATF6, and IRE1 in macrophages. Enzyme-linked immunosorbent assay was used to analyze the levels of inflammatory signal molecules, including IFN-α, IFN-β, IL-6, CCL4, CCL5, and IL-6. FITC-Annexin V was used to analyze the apoptosis of immune cells (macrophages) in mouse blood samples and to detect the concentration of calcium ions in erythrocyte cytoplasm. The results showed that the expression of erythrocyte surface protein TLR9; the distribution of STING-positive cells in macrophages; the expressions of STING, ATF6, and IRE1 in macrophages; the levels of inflammatory signal molecules; the apoptosis rate of macrophages; and the intracellular calcium concentration in erythrocytes in group B were higher than those in group A, followed by group C. These results suggest that TLR9 regulates ER stress in macrophages of mice with hemorrhagic shock through the TLR9-cGAS-STING-IFN signaling pathway. Increased expression of TLR9 enhanced macrophage activity, reduced apoptosis, enhanced inflammatory response and immune response, and restored electrolyte level, which might be a therapeutic option for the treatment of hemorrhagic shock.

Macrophage migration inhibitory factor as a diagnostic and predictive biomarker in sepsis: meta-analysis of clinical trials

The hunt for useful sepsis biomarkers is ongoing. Macrophage migration inhibitory factor (MIF) was implicated as a biomarker in sepsis, but its diagnostic and prognostic value has remained unclear in human studies. Here, we aimed at clarifying the value of MIF as a sepsis biomarker with the meta-analysis of clinical trials. PubMed, EMBASE, and Cochrane Central Register of Controlled Trials databases were searched until December 2019. From the included studies, blood MIF levels and indicators of disease severity were extracted in septic and control patient groups. Twenty-one eligible studies were identified, including data from 1876 subjects (of which 1206 had sepsis). In the septic patients, blood MIF levels were significantly higher than in healthy controls with a standardized mean difference (SMD) of 1.47 (95% confidence interval, CI: 0.96-1.97; p < 0.001) and also higher than in patient groups with nonseptic systemic inflammation (SMD = 0.94; CI: 0.51-1.38; p < 0.001). Markedly greater elevation in blood MIF level was found in the more severe forms of sepsis and in nonsurvivors than in less severe forms and in survivors with SMDs of 0.84 (CI: 0.45-1.24) and 0.75 (CI: 0.40-1.11), respectively (p < 0.001 for both). In conclusion, blood MIF level is more elevated in systemic inflammation caused by infection (i.e., sepsis) compared to noninfectious causes. In more severe forms of sepsis, including fatal outcome, MIF levels are higher than in less severe forms. These results suggest that MIF can be a valuable diagnostic and prognostic biomarker in sepsis given that well-designed clinical trials validate our findings.