[Cytokines as biomarkers in polytraumatized patients]

Dynamic bond crosslinked maca polysaccharide hydrogels with reactive oxygen species scavenging and antibacterial effects on infected wound healing

In this study, a polysaccharide fragment with antioxidant and reactive oxygen species (ROS) scavenging activities was extracted from Maca (Lepidium meyenii Walp.) and subjected to structural analyses. The fragment, characterized by the α-D-Glcp-(1 → terminal group of the main chain linked to the →4)-Glcp-(1 → end unit through an O-6 bond and the O-3 bond of 1-3-4Glcp, was modified by introducing dialdehyde structures on its glucose units. It was then crosslinked with N-carboxymethyl chitosan via the Schiff base reaction to create a multifunctional hydrogel with antibacterial and ROS scavenging properties. Polyvinyl alcohol was incorporated to form a double crosslinked gel network, and the addition of silver nanoparticles enhanced its antibacterial efficacy. This gel system can scavenge excess ROS, mitigate wound inflammation, eradicate harmful bacteria, and aid in the restoration of skin microecology. The multifunctional maca polysaccharide hydrogel shows significant potential as a medical dressing for the treatment of infected wounds.

Traumatic inflammatory response: pathophysiological role and clinical value of cytokines

Severe trauma is an intractable problem in healthcare. Patients have a widespread immune system response that is complex and vital to survival. Excessive inflammatory response is the main cause of poor prognosis and poor therapeutic effect of medications in trauma patients. Cytokines are signaling proteins that play critical roles in the body's response to injuries, which could amplify or suppress immune responses. Studies have demonstrated that cytokines are closely related to the severity of injuries and prognosis of trauma patients and help present cytokine-based diagnosis and treatment plans for trauma patients. In this review, we introduce the pathophysiological mechanisms of a traumatic inflammatory response and the role of cytokines in trauma patients. Furthermore, we discuss the potential of cytokine-based diagnosis and therapy for post-traumatic inflammatory response, although further clarification to elucidate the underlying mechanisms of cytokines following trauma is warranted.

Damage-associated molecular patterns in trauma

In 1994, the "danger model" argued that adaptive immune responses are driven rather by molecules released upon tissue damage than by the recognition of "strange" molecules. Thus, an alternative to the "self versus non-self recognition model" has been provided. The model, which suggests that the immune system discriminates dangerous from safe molecules, has established the basis for the future designation of damage-associated molecular patterns (DAMPs), a term that was coined by Walter G. Land, Seong, and Matzinger. The pathological importance of DAMPs is barely somewhere else evident as in the posttraumatic or post-surgical inflammation and regeneration. Since DAMPs have been identified to trigger specific immune responses and inflammation, which is not necessarily detrimental but also regenerative, it still remains difficult to describe their "friend or foe" role in the posttraumatic immunogenicity and healing process. DAMPs can be used as biomarkers to indicate and/or to monitor a disease or injury severity, but they also may serve as clinically applicable parameters for optimized indication of the timing for, i.e., secondary surgeries. While experimental studies allow the detection of these biomarkers on different levels including cellular, tissue, and circulatory milieu, this is not always easily transferable to the human situation. Thus, in this review, we focus on the recent literature dealing with the pathophysiological importance of DAMPs after traumatic injury. Since dysregulated inflammation in traumatized patients always implies disturbed resolution of inflammation, so-called model of suppressing/inhibiting inducible DAMPs (SAMPs) will be very briefly introduced. Thus, an update on this topic in the field of trauma will be provided.

Cytokines in Inflammatory Disease

This review aims to briefly discuss a short list of a broad variety of inflammatory cytokines. Numerous studies have implicated that inflammatory cytokines exert important effects with regard to various inflammatory diseases, yet the reports on their specific roles are not always consistent. They can be used as biomarkers to indicate or monitor disease or its progress, and also may serve as clinically applicable parameters for therapies. Yet, their precise role is not always clearly defined. Thus, in this review, we focus on the existing literature dealing with the biology of cytokines interleukin (IL)-6, IL-1, IL-33, tumor necrosis factor-alpha (TNF-α), IL-10, and IL-8. We will briefly focus on the correlations and role of these inflammatory mediators in the genesis of inflammatory impacts (e.g., shock, trauma, immune dysregulation, osteoporosis, and/or critical illness).

An overview of cytokines and heat shock response in polytraumatized patients

Early after injury, local tissue damage induces a local and systemic inflammatory response that activates the immune system and leads to the development of systemic inflammatory response syndrome (SIRS). This post-traumatic response often results in uncontrolled release of inflammatory mediators and over-activation of the immune system, which occasionally results in multiple organ dysfunction syndrome (MODS). In parallel, a state of immunosuppression develops. This counter-regulating suppression of different cellular and humoral immune functions has been termed "compensatory anti-inflammatory response syndrome (CARS)." Both SIRS and CARS occur simultaneously even in the initial phase after injury. Pro- and anti-inflammatory cytokines have been suggested to play a major role in development of SIRS, although the degree of involvement of the different cytokines is quite disparate. While TNF-α and IL-1β are quite irrelevant for predicting organ dysfunction, IL-6 is the parameter that best predicts mortality. The hyperinflammatory state seems to be the cause of post-traumatic immunosuppression and heat shock proteins (HSPs), which have been proposed as one of the endogenous stimuli for the deterioration of the immune system acting as danger-associated molecular patterns (DAMPs). Extracellular HSPA1A released from injured tissues increase up to ten times immediately after trauma and even more in patients with MODS. It has powerful immune properties that could contribute to post-traumatic immunosuppression through several mechanisms that have been previously described, so HSPs could represent trauma-associated immunomodulatory mediators. For this reason, HSPA1A has been suggested to be a helpful early prognostic biomarker of trauma after severe injury: serial quantification of serum HSPA1A and anti-Hsp70 concentrations in the first hours after trauma is proposed to be used as a predictive biomarker of MODS and immunosuppression development in polytraumatized patients.

Danger signals in trauma

This review summarizes a short list of currently discussed trauma-induced danger-associated molecular patterns (DAMP). Due to the bivalent character and often pleiotropic effects of a DAMP, it is difficult to describe its "friend or foe" role in post-traumatic inflammation and regeneration, both systemically as well locally in tissues. DAMP can be used as biomarkers to indicate or monitor disease or injury severity, but also may serve as clinically applicable parameters for better indication and timing of surgery. Due to the inflammatory processes at the local tissue level or the systemic level, the precise role of DAMP is not always clear to define. While in vitro and experimental studies allow for the detection of these biomarkers at the different levels of an organism-cellular, tissue, circulation-this is not always easily transferable to the human setting. Increased knowledge exploring the dual role of DAMP after trauma, and concentrating on their nuclear functions, transcriptional targets, release mechanisms, cellular sources, multiple functions, their interactions and potential therapeutic targeting is warranted.

Pharmacological inhibition of IL-6 trans-signaling improves compromised fracture healing after severe trauma

Patients with multiple injuries frequently suffer bone fractures and are at high risk to develop fracture healing complications. Because of its key role both in systemic posttraumatic inflammation and fracture healing, the pleiotropic cytokine interleukin-6 (IL-6) may be involved in the pathomechanisms of trauma-induced compromised fracture healing. IL-6 signals are transmitted by two different mechanisms: classic signaling via the membrane-bound receptor (mIL-6R) and trans-signaling via its soluble form (sIL-6R). Herein, we investigated whether IL-6 classic and trans-signaling play different roles in bone regeneration after severe injury. Twelve-week-old C57BL/6J mice underwent combined femur osteotomy and thoracic trauma. To study the function of IL-6, either an anti-IL-6 antibody, which inhibits both IL-6 classic and trans-signaling, or a soluble glycoprotein 130 fusion protein (sgp130Fc), which selectively blocks trans-signaling, were injected 30 min and 48 h after surgery. Bone healing was assessed using cytokine analyses, flow cytometry, histology, micro-computed tomography, and biomechanical testing. Selective inhibition of IL-6 trans-signaling significantly improved the fracture healing outcome after combined injury, as confirmed by accelerated cartilage-to-bone transformation, enhanced bony bridging of the fracture gap and improved mechanical callus properties. In contrast, global IL-6 inhibition did not affect compromised fracture healing. These data suggest that classic signaling may mediate beneficial effects on bone repair after severe injury. Selective inhibition of IL-6 trans-signaling might have therapeutic potential to treat fracture healing complications in patients with concomitant injuries.

Traumatic Injury

Traumatic injury as one of the world's most relevant but neglected health concerns results in modulated inflammasome activity, which is closely linked to the development of post-injury complications. Cytokine-producing capacity of cells is important for the appropriate immune response to trauma and requires not only synthesis and transcription of inflammasome components but also their activation. Unfortunately, the precise role of inflammasome in trauma is still largely unknown. However, in the following chapter, we provide an overview on the best described inflammasomes in the various settings of trauma, introducing the recent findings on the up-to-date best described NLRP inflammasomes and underlying cytokines in the inflammatory response to trauma.

Use of CytoSorb in Traumatic Amputation of the Forearm and Severe Septic Shock

Severe trauma associated with later disability and mortality still constitutes a major health and socioeconomic problem throughout the world. While primary morbidity and mortality are mostly related to initial injuries and early complications, secondary lethality is strongly linked to the development of systemic inflammatory response syndrome, sepsis, and ultimately multiple organ dysfunction syndrome. We herein report on a 49-year-old male patient who was admitted to the hospital after a traumatic amputation of his right forearm that was cut off while working on a landfill. After initial treatment for shock, he received immediate replantation and was transferred to the ICU. Due to the anticipated risk of a complex infection, continuous renal replacement therapy in combination with CytoSorb was initiated. During the course of the combined treatment, a rapid improvement in hemodynamics was noticed, as well as a significant reduction of IL-6 and lactate levels. Despite a recurring septic episode and the necessity for amputation, the patient clinically stabilized and underwent complete recovery. The early treatment with a combination of CVVHDF and CytoSorb was accompanied by an attenuation of the systemic inflammatory reaction, which subsided without major or permanent organ damage, despite the impressive pathogen spectrum and the pronounced local damage.

Inflammatory response after nailing

Intramedullary nailing, as the gold standard stabilisation method of most long bones, has been tailed by its extensive use as the basic tool of investigating the immune response to trauma in many large and small animal models, as well as at the clinical setting. Over the last few decades a complex map of interactions between pro and anti-inflammatory pathways has been the result of these significant global research efforts. Parallel to the evolution of modern nailing and reaming techniques, significant developments at the fields of other disciplines relevant to trauma care, has improved the contemporary management of injured patients, challenging previous concepts and altering clinical barriers. The current article aims to summarise the current understanding of the effect of instrumenting the medullary canal after trauma, and hint on potential future directions.

Does Infection-Induced Immune Activation Contribute to Dementia?

The central nervous system (CNS) is protected by a complex blood-brain barrier system; however, a broad diversity of virus, bacteria, fungi, and protozoa can gain access and cause illness. As pathogens replicate, they release molecules that can be recognized by innate immune cells. These molecules are pathogen-associated molecular patterns (PAMP) and they are identified by pattern-recognition receptors (PRR) expressed on antigen-presenting cells. Examples of PRR include toll-like receptors (TLR), receptors for advanced glycation endproducts (RAGE), nucleotide binding oligomerisation domain (NOD)-like receptors (NLR), c-type lectin receptors (CLR), RIG-I-like receptors (RLR), and intra-cytosolic DNA sensors. The reciprocal action between PAMP and PRR triggers the release of inflammatory mediators that regulate the elimination of invasive pathogens. Damage-associated molecular patterns (DAMP) are endogenous constituents released from damaged cells that also have the ability to activate the innate immune response. An increase of RAGE expression levels on neurons, astrocytes, microglia, and endothelial cells could be responsible for the accumulation of αβ-amyloid in dementia and related to the chronic inflammatory state that is found in neurodegenerative disorders.