Expression of toll-like receptors 2 and 4 is upregulated during hospital admission in traumatic patients: lack of correlation with blunted innate immune responses

Tlr2 on Bone Marrow and Non-Bone Marrow Derived Cells Regulates Inflammation and Organ Injury in Cooperation with Tlr4 During Resuscitated Hemorrhagic Shock

BACKGROUND

Although the role of TLR4 in driving inflammation and organ injury after hemorrhagic shock and resuscitation (H/R) is well established, the role of TLR2-another receptor for damage-associated molecular pattern (DAMP) molecules-is not. In this study, we used a combination of TLR2 and wild type (WT) mice treated with anti-TLR2 and anti-TLR4 neutralizing monoclonal antibodies (mAb) to discern the contribution of TLR2 relative to TLR4 to the systemic inflammatory response in murine H/R.

MATERIAL AND METHODS

WT mice, TLR2, and WT mice receiving an anti-TLR2 or an anti-TLR4 mAB (given as a pretreatment) were sacrificed at 6 or 20 h post-H/R. Bone marrow TLR2/WT chimeric mice were created to assess the importance of immune and nonimmune cell-associated TLR2.

RESULTS

TLR2 mice subjected to H/R exhibited significantly less liver damage and lower markers of systemic inflammation only at 20 h. Bone marrow chimeric mice using combinations of TLR2 mice and WT mice demonstrated that TLR2 on non-bone marrow derived cells played a dominant role in the differences at 20 h. Interestingly, WT mice treated with anti-TLR2 mAB demonstrated a reduction in organ damage and systemic inflammation at both 6 and 20 h following H/R. A combination of anti-TLR2 mAB and anti-TLR4 mAB showed that both receptors drive IP-10 and KC levels and that there is cooperation for increases in IL-6, MIG, and MCP-1 levels between TLR2 and TLR4.

CONCLUSION

These data also support the conclusion that TLR2 and TLR4 act in concert as important receptors in the host immune response to H/R.

Early decreased TLR2 expression on monocytes is associated with their reduced phagocytic activity and impaired maturation in a porcine polytrauma model

In their post-traumatic course, trauma patients suffering from multiple injuries have a high risk for immune dysregulation, which may contribute to post-injury complications and late mortality. Monocytes as specific effector cells of the innate immunity play a crucial role in inflammation. Using their Pattern Recognition Receptors (PRRs), notably Toll-Like Receptors (TLR), the monocytes recognize pathogens and/or pathogen-associated molecular patterns (PAMPs) and organize their clearance. TLR2 is the major receptor for particles of gram-positive bacteria, and initiates their phagocytosis. Here, we investigated the phagocytizing capability of monocytes in a long-term porcine severe trauma model (polytrauma, PT) with regard to their TLR2 expression. Polytrauma consisted of femur fracture, unilateral lung contusion, liver laceration, hemorrhagic shock with subsequent resuscitation and surgical fracture fixation. After induction of PT, peripheral blood was withdrawn before (-1 h) and directly after trauma (0 h), as well as 3.5 h, 5.5 h, 24 h and 72 h later. CD14+ monocytes were identified and the expression levels of H(S)LA-DR and TLR2 were investigated by flow cytometry. Additionally, the phagocytizing activity of monocytes by applying S. aureus particles labelled with pHrodo fluorescent reagent was also assessed by flow cytometry. Furthermore, blood samples from 10 healthy pigs were exposed to a TLR2-neutralizing antibody and subsequently to S. aureus particles. Using flow cytometry, phagocytizing activity was determined. P below 0.05 was considered significant. The number of CD14+ monocytes of all circulating leukocytes remained constant during the observational time period, while the percentage of CD14+H(S)LA-DR+ monocytes significantly decreased directly, 3.5 h and 5.5 h after trauma. The percentage of TLR2+ expressing cells out of all monocytes significantly decreased directly, 3.5 h and 5.5 h after trauma. The percentage of phagocytizing monocytes decreased immediately and remained lower during the first 3.5 h after trauma, but increased after 24 h. Antagonizing TLR2 significantly decreased the phagocytizing activity of monocytes. Both, decreased percentage of activated as well as TLR2 expressing monocytes persisted as long as the reduced phagocytosis was observed. Moreover, neutralizing TLR2 led to a reduced capability of phagocytosis as well. Therefore, we assume that reduced TLR2 expression may be responsible for the decreased phagocytizing capacity of circulating monocytes in the early post-traumatic phase.

Prehospital immune responses and development of multiple organ dysfunction syndrome following traumatic injury: A prospective cohort study

BACKGROUND

Almost all studies that have investigated the immune response to trauma have analysed blood samples acquired post-hospital admission. Thus, we know little of the immune status of patients in the immediate postinjury phase and how this might influence patient outcomes. The objective of this study was therefore to comprehensively assess the ultra-early, within 1-hour, immune response to trauma and perform an exploratory analysis of its relationship with the development of multiple organ dysfunction syndrome (MODS).

METHODS AND FINDINGS

The immune and inflammatory response to trauma was analysed in 89 adult trauma patients (mean age 41 years, range 18-90 years, 75 males) with a mean injury severity score (ISS) of 24 (range 9-66), from whom blood samples were acquired within 1 hour of injury (mean time to sample 42 minutes, range 17-60 minutes). Within minutes of trauma, a comprehensive leukocytosis, elevated serum pro- and anti-inflammatory cytokines, and evidence of innate cell activation that included neutrophil extracellular trap generation and elevated surface expression of toll-like receptor 2 and CD11b on monocytes and neutrophils, respectively, were observed. Features consistent with immune compromise were also detected, notably elevated numbers of immune suppressive CD16BRIGHT CD62LDIM neutrophils (82.07 x 106/l ± 18.94 control versus 1,092 x 106/l ± 165 trauma, p < 0.0005) and CD14+HLA-DRlow/- monocytes (34.96 x 106/l ± 4.48 control versus 95.72 x 106/l ± 8.0 trauma, p < 0.05) and reduced leukocyte cytokine secretion in response to lipopolysaccharide stimulation. Exploratory analysis via binary logistic regression found a potential association between absolute natural killer T (NKT) cell numbers and the subsequent development of MODS. Study limitations include the relatively small sample size and the absence of data relating to adaptive immune cell function.

CONCLUSIONS

Our study highlighted the dynamic and complex nature of the immune response to trauma, with immune alterations consistent with both activation and suppression evident within 1 hour of injury. The relationship of these changes, especially in NKT cell numbers, to patient outcomes such as MODS warrants further investigation.

Impaired Surface Expression of HLA-DR, TLR2, TLR4, and TLR9 in Ex Vivo-In Vitro Stimulated Monocytes from Severely Injured Trauma Patients

Objective. Trauma patients (TP) frequently develop an imbalanced immune response that often causes infectious postinjury complications. Monocytes show a diminished capability of both producing proinflammatory cytokines and antigen presentation after trauma. TLR2, TLR4, and TLR9 recognize pathogens and subsequently activate monocytes. While there are conflictive data about TLR2 and TLR4 expression after trauma, no studies about the expression of TLR2, TLR4, TLR9, and HLA-DR on monocytes from TP after their secondary ex vivo-in vitro "hit" have been reported. Methods/Results. Ex vivo-in vitro lipopolysaccharide- (LPS-) stimulated blood from TP showed diminished interleukin- (IL-) 1β-release in TP for five postinjury days compared to healthy volunteers (HV). The recovery was observed at day 5. In parallel, monocytes from TP showed an impaired capability of TLR2, TLR4, and TLR9 expression after secondary stimulation compared to HV, while the measurement of unstimulated samples showed significant reduction of TLR4 and TLR9 at ED. Furthermore, HLA-DR decreased after trauma and was even more profound by stimulation of monocytes. Ratio of monocytes to leukocytes was significantly increased at days 6 and 7 after trauma compared to HV. Conclusion. Impaired expression of TLRs and HLA-DR in acute inflammatory conditions may be responsible for the well-described monocyte paralysis after severe trauma.

Gene expression disorders of innate antibacterial signaling pathway in pancreatic cancer patients: implications for leukocyte dysfunction and tumor progression

The study was carried out to investigate changes in gene expression of innate antibacterial signaling pathways in patients with pancreatic cancer. Expression of the following genes was measured in peripheral blood leukocytes of 55 patients with pancreatic adenocarcinoma using real-time polymerase chain reaction (RT-PCR): TLR4, NOD1, MyD88, TRAF6 and HMGB1. The levels of expression of TLR4, NOD1 and TRAF6 genes were significantly elevated (p = 0.007; p = 0.001 and p = 0.01, respectively), while MyD88 expression was markedly reduced (p = 0.0002), as compared to controls. Expression of TLR4 and NOD1 exceeded the normal level more than 3.5-fold and there was a significant correlation found between the expression of these genes (r = 0.558, p < 0.001). TLR4, NOD1 and MyD88 genes were expressed at a similar level both before and after surgery. No significant changes in the expression of HMGB1 gene were observed. The results of the study clearly indicate abnormal expression of genes belonging to innate antibacterial signaling pathways in peripheral blood leukocytes of patients with pancreatic cancer, which may lead to leukocyte dysfunction. Overexpression of TLR4, NOD1 and TRAF6 genes, and decreased MyD88 gene expression may contribute to chronic inflammation and tumor progression by up-regulation of the innate antibacterial response. The parameters tested are useful for monitoring innate immunity gene disorders and pancreatic cancer progression.

Lack of effect of glutamine administration to boost the innate immune system response in trauma patients in the intensive care unit

Introduction

The use of glutamine as a dietary supplement is associated with a reduced risk of infection. We hypothesized that the underlying mechanism could be an increase in the expression and/or functionality of Toll-like receptors (TLR), key receptors sensing infections. The objective of this study was to evaluate whether glutamine supplementation alters the expression and functionality of TLR2 and TLR4 in circulating monocytes of trauma patients admitted to the intensive care unit (ICU).

Methods

We designed a prospective, randomized and single-blind study. Twenty-three patients received parenteral nutrition (TPN) with a daily glutamine supplement of 0.35 g/kg. The control group (20 patients) received an isocaloric-isonitrogenated TPN. Blood samples were extracted before treatment, at 6 and 14 days. Expression of TLR2 and TLR4 was determined by flow cytometry. Monocytes were stimulated with TLR specific agonists and cytokines were measured in cell culture supernatants. Phagocytic ability of monocytes was also determined.

Results

Basal characteristics were similar in both groups. Monocytes from patients treated with glutamine expressed the same TLR2 levels as controls before treatment (4.9 ± 3.5 rmfi vs. 4.3 ± 1.9 rmfi, respectively; P = 0.9), at Day 6 (3.8 ± 2.3 rmfi vs. 4.0 ± 1.7 rmfi, respectively; P = 0.7) and at Day 14 (4.1 ± 2.1 rfim vs. 4.6 ± 1.9 rmfi, respectively; P = 0.08). TLR4 levels were not significantly different between the groups before treatment: (1.1 ± 1 rmfi vs 0.9 ± 0.1 rmfi respectively; P = 0.9), at Day 6 (1.1 ± 1 rmfi vs. 0.7 ± 0.4 rmfi respectively; P = 0.1) and at Day 14 (1.4 ± 1.9 rmfi vs. 1.0 ± 0.6 rmfi respectively; P = 0.8). No differences in cell responses to TLR agonists were found between groups. TLR functionality studied by phagocytosis did not vary between groups.

Conclusions

In trauma patients in the intensive care unit, TPN supplemented with glutamine does not improve the expression or the functionality of TLRs in peripheral blood monocytes.

Trial registration

ClinicalTrials.gov Identifier: NCT01250080.