Synergistic effects of mixed TiAlV and polyethylene wear particles on TNFα response in THP-1 macrophages / Synergistische Effekte gemischter TiAlV- und Polyethylen-Abriebpartikel auf die TNFα-Antwort in THP-1 Makrophagen

Emerging factors affecting peri-implant bone metabolism

Implant dentistry has evolved to the point that standard implant osseointegration is predictable. This is attributed in part to the advancements in material sciences that have led toward improvements in implant surface technology and characteristics. Nonetheless, there remain several cases where implant therapy fails (specifically at early time points), most commonly attributed to factors affecting bone metabolism. Among these patients, smokers are known to have impaired bone metabolism and thus be subject to higher risks of early implant failure and/or late complications related to the stability of the peri-implant bone and mucosal tissues. Notably, however, emerging data have unveiled other critical factors affecting osseointegration, namely, those related to the metabolism of bone tissues. The aim of this review is to shed light on the effects of implant-related factors, like implant surface or titanium particle release; surgical-related factors, like osseodensification or implanted biomaterials; various drugs, like selective serotonin reuptake inhibitors, proton pump inhibitors, anti-hypertensives, nonsteroidal anti-inflammatory medication, and statins, and host-related factors, like smoking, diet, and metabolic syndrome on bone metabolism, and aseptic peri-implant bone loss. Despite the infectious nature of peri-implant biological complications, these factors must be surveyed for the effective prevention and management of peri-implantitis.

Subgingival titanium wire implantation induces weak inflammatory responses but does not promote substantial T cell activation

Titanium is a biocompatible material commonly used for dental treatments. However, the detailed mechanism underlying the weak biological activity of titanium has not been elucidated. We investigated both the inflammatory responses and T cell activation induced by solid titanium in the gingiva in mice. Both titanium and nickel wire implantation promoted neutrophil infiltration into the gingiva on day 2. Nickel, but not titanium, wire implantation enhanced proinflammatory cytokine expression and dendritic cell activity in gingival tissue by day 2. Nickel wire implantation enhanced the activity of T cells in draining lymph nodes on day 5. Moreover, T cell and neutrophil infiltration and elevated proinflammatory cytokine expression in the gingival tissue were still observed on day 5. However, no such augmented biological responses were observed after titanium wire implantation. These findings suggest that, unlike nickel, solid titanium does not induce sufficient inflammatory responses leading to T cell activation in gingival tissue.

Innate immunity sensors participating in pathophysiology of joint diseases: a brief overview

The innate immune system consists of functionally specialized "modules" that are activated in response to a particular set of stimuli via sensors located on the surface or inside the tissue cells. These cells screen tissues for a wide range of exogenous and endogenous danger/damage-induced signals with the aim to reject or tolerate them and maintain tissue integrity. In this line of thinking, inflammation evolved as an adaptive tool for restoring tissue homeostasis. A number of diseases are mediated by a maladaptation of the innate immune response, perpetuating chronic inflammation and tissue damage. Here, we review recent evidence on the cross talk between innate immune sensors and development of rheumatoid arthritis, osteoarthritis, and aseptic loosening of total joint replacements. In relation to the latter topic, there is a growing body of evidence that aseptic loosening and periprosthetic osteolysis results from long-term maladaptation of periprosthetic tissues to the presence of by-products continuously released from an artificial joint.

[Bone defect adjusted strategy in revision arthroplasty of the hip : Wich implant in wich situation? Innovations and approved methods]

BACKGROUND

Revision total hip arthroplasty is of rising importance, with 35,000 procedures a year in Germany.

OBJECTIVES

Primary stability of the revision implant, reconstruction of the anatomical hip center, reconstruction of bone stock, and permanent secondary integration are the main priorities.

METHODS

Current literature and examples from our own experience are presented.

RESULTS AND CONCLUSIONS

Novel developments from basic research and industrial partners extend the possibilities for treating affected patients. For an integrated therapy concept in implant selection criteria, such as situation and structure of the defect, combination with any remaining implants, causes of loosening and failure, implant allergy, and patient-specific parameters should be taken into consideration.

In vivo response to cross-linked polyethylene and polycarbonate-urethane particles

This study was undertaken to examine macrophage response to polycarbonate-urethane, a proposed alternative material to polyethylene in acetabular components of total hip arthroplasty. Polyethylene wear debris from total joint replacements has been linked to osteolysis and implant lifespan. It has been shown in vitro, that polyethylene particles cleaned of endotoxin generate less of an inflammatory cytokine response than endotoxin bound particles. Comparative particle induced effects on implant fixation were tested using endotoxin free cross-linked ultra-high molecular weight polyethylene (x-UHMWPE) and polycarbonate-urethane (PCU) particles with and without intraperitoneal injection (IP) of lipopolysaccharide (LPS) using a Ti-alloy femoral intramedullary nail rat model. MicroCT and mechanical testing assessment of peri-implant bone indicated significantly less bone and lower fixation strength, respectively, when the implant was surrounded by xUHMWPE particles compared to PCU particles (with and without LPS IP). This indicates particles of PCU may be less disruptive to bone-implant fixation than x-UHMWPE in vivo, under both LPS free and challenged conditions.

A review of the biologic effects of spine implant debris: Fact from fiction

BACKGROUND

Biologic-reactivity to implant-debris is the primary determinant of long-term clinical performance. The following reviews: 1) the physical aspects of spinal-implant debris and 2) the local and systemic biologic responses to implant debris.

METHODS

Methods included are: 1) gravimetric wear analysis; 2) SEM and LALLS; 3) metal-ion analysis; 4) ELISA, toxicity testing, patch testing; and 5) metal-lymphocyte transformation testing (metal-LTT).

RESULTS

Wear and corrosion of spine-implants produce particles and ions. Particles (0.01-1000 μm) are generally submicron ( <1 µm). Wear rates of metal-on-polymer and metal-on-metal disc arthroplasties are approximately 2-20 and 1 mm(3)/yr, respectively. Metal-on-metal total disc replacement components have significant increases in circulating metal (less than 10-fold that of controls at 4 ppb-Co and 3 ppb-Cr or ng/mL). Debris reactivity is local and systemic. Local inflammation is caused primarily by ingestion of debris by local macrophages, which produce pro-inflammatory cytokines TNFα, IL-1β, IL-6, and PGE2. Systemic responses associated with implant-debris have been limited to hypersensitivity reactions. Elevated amounts of in the liver, spleen, etc of patients with failed TJA have not been associated with remote toxicological or carcinogenic pathology to date. Implant debris are differentially bioreactive. Greater numbers are pro-inflammatory; the smaller-sized debris are more bioreactive by virtue of their greater numbers (dose) for a given amount of implant mass loss (one 100-μm-diameter particle is equivalent in mass to 1 million 1-μm-diameter particles). Elongated particles are pro-inflammatory (ie, aspect ratio of greater than 3). Metal particles are more proinflammatory than polymers, ceteris paribus.

CONCLUSION

Spinal arthroplasty designs have been in use for more than 20 years internationally; therefore, concerns about neuropathology, toxicity, and carcinogenicity are mitigated. Debris-induced inflammation still depends on the individual and the type of debris. The consequence of debris-induced inflammation is continued; vigilance by physicians is recommended monitoring of spinal implants using physical exams and testing of metal content and bioreactivity, as is planning for the likelihood of revision in younger individuals.

Upregulation of LITAF mRNA expression upon exposure to TiAlV and polyethylene wear particles in THP-1 macrophages

Tumor necrosis factor alpha (TNFalpha) plays a fundamental role in the pathogenesis of wear particle-induced periprosthetic osteolysis. However, particle-induced mechanisms that control TNFalpha gene expression are not yet well characterized. LITAF [lipopolysaccharide (LPS)-induced TNFalpha factor] is a novel transcription factor that regulates expression of the TNFalpha gene, but nothing is known about its role in wear particle-induced osteolysis. We evaluated the effect of titanium aluminum vanadium (TiAlV) and polyethylene particles on mRNA expression of LITAF. A human monocytic leukemia cell line (THP-1) was used in this in vitro study. THP-1 monocytes were differentiated to macrophage-like cells and exposed to LPS-detoxified polyethylene particles and prosthesis-derived TiAlV particles. Supernatant was used for TNFalpha protein measurement and total RNA was extracted from cells. LITAF was analyzed at the mRNA level using semiquantitative RT-PCR. Both polyethylene and TiAlV particles induced significant upregulation of LITAF mRNA that was followed by a significant TNFalpha response. These effects were dependent on the particle dose. Low particle concentrations exhibited no significant effect on expression of TNFalpha and LITAF mRNA. In comparison to exposure to polyethylene and TiAlV particles, LPS stimulation exhibited similar upregulation of LITAF mRNA, but led to an overwhelming TNFalpha response. Our findings provide evidence that LITAF is implicated in the pathogenesis of wear particle-induced osteolysis.