Ionic cobalt but not metal particles induces ROS generation in immune cells in vitro

Difference in the cellular response following THP-1 derived phagocytic monocyte cells exposure to commercial aluminum-based adjuvants and aluminum-containing vaccines

BACKGROUND

Aluminum-based adjuvants (ABAs) enhance the immune response following vaccine injection. Their mechanisms of action are not fully understood, and their bio-persistency have been described associated with long-term adverse effects.

METHODS

We evaluated and compared the cellular effects of the two main ABAs and whole vaccines on ATP production, ROS generation and cytokines production (IL-6 and IL-10), using THP-1 cells.

RESULTS

ABAs altered the cell energy metabolism by increasing ROS production after 24 h and reducing ATP production after 48 h. In addition, both ABAs and whole vaccines induced different kinetics of IL-6 production, whereas only ABAs induced IL-10 secretion.

CONCLUSION

This study showed clearly, for a first time, a difference in cellular response to the ABAs and whole vaccines which should be taken into consideration in future studies focusing on the effect of ABA in vaccines. Future studies on ABAs should also pay attention to mitochondrial function alterations following exposure to ABA-containing vaccines.

Association between serum heavy metal levels and diabetic retinopathy in NHANES 2011-2020

The present study utilized the National Health and Nutrition Examination Survey (NHANES) database to examine the relationship between serum levels of heavy metals and Diabetic retinopathy (DR) in individuals aged over 30 years with type 2 diabetes mellitus (T2DM) in the United States. A cross-sectional analysis was conducted on 1583 individuals with T2DM from the NHANES 2011-2020, including 331 individuals in the DR group and 1252 individuals in the non-DR group. We collected data on serum levels of heavy metals, DR, and serum albumin for descriptive statistics, linear regression, and logistical regression analysis. After adjusting for age, gender, race and other factors, there was no statistically significant association between blood cadmium, selenium, mercury, or lead and DR. However, serum manganese (Mn) and DR had a significant negative association (β = - 0.2045, 95% CI = - 0.3484, - 0.0606). Serum albumin partially modulated the indirect influence of serum Mn on the incidence of DR, accounting for 12.80% of the association between serum Mn and DR. There was a negative association between serum Mn levels and the prevalence of DR in people with T2DM. Mn intake at least in this study has a little influence on the onset and development of DR.

Interaction pathways of implant metal localized corrosion and macrophage inflammatory reactions

Macrophages play a central role in immunological responses to metallic species associated with the localized corrosion of metallic implants, and mediating in peri-implant inflammations. Herein, the pathways of localized corrosion-macrophage interactions were systematically investigated on 316L stainless steel (SS) implant metals. Electrochemical monitoring under macrophage-mediated inflammatory conditions showed a decreased pitting corrosion resistance of 316L SSs in the presence of RAW264.7 cells as the cells would disrupt biomolecule adsorbed layer on the metal surface. The pitting potentials were furtherly decreased when the RAW264.7 cells were induced to the M1 pro-inflammatory phenotype by the addition of lipopolysaccharide (LPS), and pitting corrosion preferentially initiated at the peripheries of macrophages. The overproduction of aggressive ROS under inflammatory conditions would accelerate the localized corrosion of 316L SS around macrophages. Under pitting corrosion condition, the viability and pro-inflammatory polarization of RAW264.7 cells were region-dependent, lower viability and more remarkable morphology transformation of macrophages in the pitting corrosion region than the pitting-free region. The pitting corrosion of 316L SS induced high expression of CD86, TNF-α, IL-6 and high level of intracellular ROS in macrophages. Uneven release of metallic species (Fe2+, Cr3+, Ni2+, etc) and uneven distribution of surface overpotential stimulated macrophage inflammatory responses near the corrosion pits. A synergetic effect of localized corrosion and macrophages was revealed, which could furtherly promote localized corrosion of 316L SS and macrophage inflammatory reactions. Our results provided direct evidence of corrosion-macrophage interaction in metallic implants and disclosed the pathways of this mutual stimulation effect.

In vivo corrosion on retrieved hip endoprostheses and in vitro effects of corrosion products on bone mineralization

In vivo corrosion of modular endoprostheses remains a great concern, as the release of heavy metal ions can impair the implant's service life and the wellbeing of the patient. The detailed corrosion mechanisms that occur in vivo are so far not completely understood. In this context, the effects of implant released cobalt (Co) and chromium (Cr) ions on osteoblast mineralization and gene expression have not been investigated extensively. This comprehensive study aimed at furthering the understanding of in vivo implant corrosion from the clinical signs via prosthesis retrievals and histology of the synovial membranes down to the molecular processes instigated by corrosion products and its effects on bone mineralization. A detailed in vivo failure analysis was performed investigating 22 retrieved hip endoprostheses from different manufacturers and taper material combinations. The aim was to find a correlation of taper damage and especially corrosion to susceptible biomedical alloys and its effect on periprosthetic tissue as well as the clinical implant performance with regard to revision diagnosis and presence of radiolucent lines (RLL). A second part investigated the effects of Co and Cr ions on the in vitro mineralization process of osteoblasts. Cell cultures were exposed to relevant concentrations of CoCl2 and CrCl3 (0 μM, 100 μM, 200 μM) with and without addition of phosphate. Mineralization behavior was analyzed with Alizarin Red assay and Von Kossa staining of calcium depots, alkaline phosphatase activity of osteoblasts and gene expression was analyzed with real time quantitative PCR. The retrieval study provides evidence of in vivo fretting and crevice corrosion on all metallic tapers combined with either ceramic or metal femoral heads. Within the modular taper junctions, selective dissolution of the α phase occurred in wrought TiAl6V4 alloys, and etching of the fine-grained wrought CoCr28Mo6 alloy implants was observed in formed crevices. In addition, significant amounts of wear particles and corrosion products were detected in retrieved synovial membranes. An increased risk for the occurrence of a RLL in the proximal zones was determined for patients with a corroded mixed metal taper. Whereas Co ions have hardly any effects on mineralization, Cr ions cause a significant concentration dependent decrease in mineralization rate of osteoblasts. However, this effect is alleviated by addition of a phosphate source. Our data reveal that Cr ions depleted dissolved phosphates by forming an insoluble complex (CrPO4), which inhibits the phosphate dependent mineralization process. No significant effect of the heavy metal ions on osteoblast activity by means of alkaline phosphate activity as well as on gene expression is determined. This study broadens the understanding of in vivo corrosion of metallic modular implants and its clinically relevant effects on mineralization. Based on these findings, in vivo corrosion of CoCr28Mo6 endoprostheses should be limited to avoid inhibitory effects of Cr3+ on bone mineralization which can contribute to premature implant failure.

The progress in titanium alloys used as biomedical implants: From the view of reactive oxygen species

Titanium and Titanium alloys are widely used as biomedical implants in oral and maxillofacial surgery, due to superior mechanical properties and biocompatibility. In specific clinical populations such as the elderly, diabetics and patients with metabolic diseases, the failure rate of medical metal implants is increased significantly, putting them at increased risk of revision surgery. Many studies show that the content of reactive oxygen species (ROS) in the microenvironment of bone tissue surrounding implant materials is increased in patients undergoing revision surgery. In addition, the size and shape of materials, the morphology, wettability, mechanical properties, and other properties play significant roles in the production of ROS. The accumulated ROS break the original balance of oxidation and anti-oxidation, resulting in host oxidative stress. It may accelerate implant degradation mainly by activating inflammatory cells. Peri-implantitis usually leads to a loss of bone mass around the implant, which tends to affect the long-term stability and longevity of implant. Therefore, a great deal of research is urgently needed to focus on developing antibacterial technologies. The addition of active elements to biomedical titanium and titanium alloys greatly reduce the risk of postoperative infection in patients. Besides, innovative technologies are developing new biomaterials surfaces conferring anti-infective properties that rely on the production of ROS. It can be considered that ROS may act as a messenger substance for the communication between the host and the implanted material, which run through the entire wound repair process and play a role that cannot be ignored. It is necessary to understand the interaction between oxidative stress and materials, the effects of oxidative stress products on osseointegration and implant life as well as ROS-induced bactericidal activity. This helps to facilitate the development of a new generation of well-biocompatible implant materials with ROS responsiveness, and ultimately prolong the lifespan of implants.

Immune response differences in degradable and non-degradable alloy implants

Alloy based implants have made a great impact in the clinic and in preclinical research. Immune responses are one of the major causes of failure of these implants in the clinic. Although the immune responses toward non-degradable alloy implants are well documented, there is a poor understanding of the immune responses against degradable alloy implants. Recently, there have been several reports suggesting that degradable implants may develop substantial immune responses. This phenomenon needs to be further studied in detail to make the case for the degradable implants to be utilized in clinics. Herein, we review these new recent reports suggesting the role of innate and potentially adaptive immune cells in inducing immune responses against degradable implants. First, we discussed immune responses to allergen components of non-degradable implants to give a better overview on differences in the immune response between non-degradable and degradable implants. Furthermore, we also provide potential areas of research that can be undertaken that may shed light on the local and global immune responses that are generated in response to degradable implants.

Advances of Cobalt Nanomaterials as Anti-Infection Agents, Drug Carriers, and Immunomodulators for Potential Infectious Disease Treatment

Infectious diseases remain the most serious public health issue, which requires the development of more effective strategies for infectious control. As a kind of ultra-trace element, cobalt is essential to the metabolism of different organisms. In recent decades, nanotechnology has attracted increasing attention worldwide due to its wide application in different areas, including medicine. Based on the important biological roles of cobalt, cobalt nanomaterials have recently been widely developed for their attractive biomedical applications. With advantages such as low costs in preparation, hypotoxicity, photothermal conversion abilities, and high drug loading ability, cobalt nanomaterials have been proven to show promising potential in anticancer and anti-infection treatment. In this review, we summarize the characters of cobalt nanomaterials, followed by the advances in their biological functions and mechanisms. More importantly, we emphatically discuss the potential of cobalt nanomaterials as anti-infectious agents, drug carriers, and immunomodulators for anti-infection treatments, which might be helpful to facilitate progress in future research of anti-infection therapy.

A Review of Biomaterials and Associated Performance Metrics Analysis in Pre-Clinical Finite Element Model and in Implementation Stages for Total Hip Implant System

Total hip replacement (THR) is a common orthopedic surgery technique that helps thousands of individuals to live normal lives each year. A hip replacement replaces the shattered cartilage and bone with an implant. Most hip implants fail after 10–15 years. The material selection for the total hip implant systems is a major research field since it affects the mechanical and clinical performance of it. Stress shielding due to excessive contact stress, implant dislocation due to a large deformation, aseptic implant loosening due to the particle propagation of wear debris, decreased bone remodeling density due to the stress shielding, and adverse tissue responses due to material wear debris all contribute to the failure of hip implants. Recent research shows that pre-clinical computational finite element analysis (FEA) can be used to estimate four mechanical performance parameters of hip implants which are connected with distinct biomaterials: von Mises stress and deformation, micromotion, wear estimates, and implant fatigue. In vitro, in vivo, and clinical stages are utilized to determine the hip implant biocompatibility and the unfavorable local tissue reactions to different biomaterials during the implementation phase. This research summarizes and analyses the performance of the different biomaterials that are employed in total hip implant systems in the pre-clinical stage using FEA, as well as their performances in in vitro, in vivo, and in clinical studies, which will help researchers in gaining a better understanding of the prospects and challenges in this field.

Experimental Investigation of Material Transfer on Bearings for Total Hip Arthroplasty—A Retrieval Study on Ceramic and Metallic Femoral Heads

Metallic deposition is a commonly observed phenomenon on the surface of revised femoral heads in total hip arthroplasty and can lead to increased wear due to third bodies. In order to find out the origin and composition of the transfer material, 98 retrieved femoral heads of different materials were examined with regard to the cause of revision, localization, pattern and composition of the transfer material by energy dispersive X-ray spectroscopy. We found that in 53.1%, the deposition was mostly in the region of the equator and the adjacent pole of the femoral heads. The most common cause for revision of heads with metallic deposition was polyethylene wear (43.9%). Random stripes (44.9%), random patches (41.8%) and solid patches (35.7%) were most prevalent on retrieved femoral heads. Random patches were a typical pattern in ceramic-on-ceramic bearing couples. The solid patch frequently occurred in association with dislocation of the femoral head (55%). The elemental analysis of the depositions showed a variety of different materials. In most cases, titanium was an element of the transferred material (76.5%). In addition to metallic components, several non-metallic components were also detected, such as carbon (49%) or sulfur (4.1%). Many of the determined elements could be assigned with regard to their origin with the help of the associated revision cause. Since the depositions lead to an introduction of third-body particles and thus to increased wear, the depositions on the bearing surfaces should be avoided in any case.

Immunological Mechanisms of Metal Allergies and the Nickel-Specific TCR-pMHC Interface

Besides having physiological functions and general toxic effects, many metal ions can cause allergic reactions in humans. We here review the immune events involved in the mediation of metal allergies. We focus on nickel (Ni), cobalt (Co) and palladium (Pd), because these allergens are among the most prevalent sensitizers (Ni, Co) and immediate neighbors in the periodic table of the chemical elements. Co-sensitization between Ni and the other two metals is frequent while the knowledge on a possible immunological cross-reactivity using in vivo and in vitro approaches remains limited. At the center of an allergic reaction lies the capability of a metal allergen to form T cell epitopes that are recognized by specific T cell receptors (TCR). Technological advances such as activation-induced marker assays and TCR high-throughput sequencing recently provided new insights into the interaction of Ni2+ with the αβ TCR-peptide-major histocompatibility complex (pMHC) interface. Ni2+ functionally binds to the TCR gene segment TRAV9-2 or a histidine in the complementarity determining region 3 (CDR3), the main antigen binding region. Thus, we overview known, newly identified and hypothesized mechanisms of metal-specific T cell activation and discuss current knowledge on cross-reactivity.

The gut microbiota may be a novel pathogenic mechanism in loosening of orthopedic implants in rats

Particles released from implants cause inflammatory bone loss, which is a key factor in aseptic loosening, the most common reason for joint replacement failure. With the anticipated increased incidence of total joint replacement in the next decade, implant failure will continue to burden patients. The gut microbiome is increasingly recognized as an important factor in bone physiology, however, its role in implant loosening is currently unknown. We tested the hypothesis that implant loosening is associated with changes in the gut microbiota in a preclinical model. When the particle challenge caused local joint inflammation, decreased peri-implant bone volume, and decreased implant fixation, the gut microbiota was affected. When the particle challenge did not cause this triad of local effects, the gut microbiota was not affected. Our results suggest that cross-talk between these compartments is a previously unrecognized mechanism of failure following total joint replacement.

In vitro evaluation of human myoblast function after exposure to cobalt and chromium ions

The replacement of a native hip joint by a metal-on-metal prosthesis may induce deleterious inflammatory side effects that are associated with the release of wear particles and metal ions. These events are referred to the adverse reaction to metal debris (ARMD) and the adverse local tissue reaction (ALTR). While wear particles seem involved in ARMD, the role of metal ions in ALTR and their impact on myoblasts, located in the prosthesis vicinity, has not been fully identified. To clarify this issue we investigated, using an in vitro culture system, the effect of cobalt and/or chromium ions (Co²⁺ and/or Cr³⁺ ) on human myoblast proliferation, cellular differentiation, and inflammatory marker expression. Freshly isolated human myoblasts were cultured in media supplemented with graded concentrations of Co²⁺ and/or Cr³⁺ . Co²⁺ induced a concentration-dependent decrease of both myoblast viability and myogenic differentiation while Cr³⁺ did not. Co²⁺ or Co²⁺ /Cr³⁺ also induced the upregulation of ICAM-1, whereas HLA-DR expression was unaffected. Moreover, allogenic monocytes induced the synergistic increase of Co²⁺ -induced ICAM-1 expression. We also found that Co²⁺ stabilized HIF-1α and increased TLR4, tumor necrosis factor-alpha (TNF-α), and interleukin 1β (IL-1β) expression in a dose and time-dependent manner in human myoblasts. This study showed that Co²⁺ , but not Cr³⁺ , was toxic toward myoblasts and induced, in the surviving cells, expression of inflammatory markers such as ICAM-1, TLR4, TNF-α, and IL-1β. This suggests that Co²⁺ , most efficiently in the presence of monocytes, may be a key inducer of ALTR, which may, if severe and long-lasting, eventually result in prosthesis loosening.

Biological Reactions to Metal Particles and Ions in the Synovial Layer of Mice

Metal particles and ions released from implants not only have a fundamental effect on the longevity of total joint replacements, but can also be disseminated to remote organs. Periprosthetic tissues harvested during revision surgeries mainly reflect end-stage failure but may not adequately reveal initial biological reactions and systemic side effects. Therefore, primary reactions caused by metal particles and ions were investigated in an established murine model. Left knee joints in three groups, each consisting of ten female BALB/c mice, received injections of metal ions (MI), metal particles (MP) and phosphate-buffered saline (PBS) (control). Seven days after the injection, immunohistochemical analyses of the synovial layer were performed with respect to some biological markers including Tumor necrosis factor -α (TNF-α), Interleukin-6 (IL-6), Interleukin-1β (IL-1β), Cluster of Differentiation 45 (CD45), Cluster of Differentiation 68 (CD68) and Cluster of Differentiation 3(CD3). The MP group showed significantly enhanced proinflammatory cytokine expression (TNF-α, IL-6 and IL-1β) compared with the other groups (p < 0.05). Interestingly, CD3, as a marker for T lymphocytes, did not increase in any of the groups. The MI group showed a significantly increased expression of CD45 compared with the control group (p < 0.05). Therefore, during the primary process, metal particles have stronger pro-inflammatory potential than metal ions, and T lymphocytes did not seem to be activated in our murine model. Systemic reactions caused by metal particles and ions were found by observing the untreated right knees.

Reactive oxygen/nitrogen species (ROS/RNS) and oxidative stress in arthroplasty

The interplay between implant design, biomaterial characteristics, and the local microenvironment adjacent to the implant is of utmost importance for implant performance and success of the joint replacement surgery. Reactive oxygen and nitrogen species (ROS/RNS) are among the various factors affecting the host as well as the implant components. Excessive formation of ROS and RNS can lead to oxidative stress, a condition that is known to damage cells and tissues and also to affect signaling pathways. It may further compromise implant longevity by accelerating implant degradation, primarily through activation of inflammatory cells. In addition, wear products of metallic, ceramic, polyethylene, or bone cement origin may also generate oxidative stress themselves. This review outlines the generation of free radicals and oxidative stress in arthroplasty and provides a conceptual framework on its implications for soft tissue remodeling and bone resorption (osteolysis) as well as implant longevity. Key findings derived from cell culture studies, animal models, and patients' samples are presented. Strategies to control oxidative stress by implant design and antioxidants are explored and areas of controversy and challenges are highlighted. Finally, directions for future research are identified. A better understanding of the host-implant interplay and the role of free radicals and oxidative stress will help to evaluate therapeutic approaches and will ultimately improve implant performance in arthroplasty.

Mechanisms of Adverse Local Tissue Reactions to Hip Implants

Adverse Local Tissue Reactions (ALTRs) are one of the main causes of hip implant failures. Although the metal release from the implants is considered as a main etiology, the mechanisms, and the roles of the released products are topics of ongoing research. The alloys used in the hip implants are considered biocompatible and show negligible corrosion in the body environment under static conditions. However, modularity and its associated mechanically assisted corrosion have been shown to release metal species into the body fluids. ALTRs associated with metal release have been observed in hip implants with metal-on-metal articulation initially, and later with metal-on-polyethylene articulation, the most commonly used design in current hip replacement. The etiological factors in ALTRs have been the topics of many studies. One commonly accepted theory is that the interactions between the metal species and body proteins and cells generate a delayed type IV hypersensitivity reaction leading to ALTRs. However, lymphocyte reactions are not always observed in ALTRS, and the molecular mechanisms have not been clearly demonstrated. A more accepted mechanism is that cell damage generated by metal ions may trigger the secretion of cytokines leading to the inflammatory reactions observed in ALTRs. In this inflammatory environment, some patients would develop hypersensitivity that is associated with poor outcomes. Concerns over ALTRS have brought significant impact to both the clinical selection and development of hip implants. This review is focused on the mechanisms of ALTRs, specifically, the metal release process and the roles of the metal species released in the etiology and pathogenesis of the disease. Hopefully, our presentation and discussion of this biological process from a material perspective could improve our current understanding on the ALTRs and provide useful guidance in developing preventive solutions.