Gallium nitrate suppresses lupus in MRL/lpr mice

In vitro and in vivo studies of a newly synthesized copper-cetyl tri-methyl ammonium bromide combined with gallium oxide nanoparticles complex as an antitumor agent against hepatocellular carcinoma

Objective: Hepatocellular carcinoma (HCC) is one of the most leading causes of death worldwide. Previous studies reported that gallium alone and cetyltrimethylammonium bromide (CTAB) have antineoplastic activities; therefore, this study aimed to evaluate the activity of copper-cetyl tri-methyl ammonium bromide with gallium oxide nanoparticles (Cu-CTAB+GaO-NPs) against HCC by using in vitro and in vivo studies. Methods: In vitro study was performed to evaluate the cytotoxic effects of Cu-CTAB+GaO-NPs and GaO-NPs on HepG-2 cell line using crystal violet dye assay. In vivo study was done on diethyl nitrosamine (DEN) induced HCC Wister rats. Rats were randomly divided into eight groups; control, Cu-CTAB, GaO-NPs, Cu-CTAB+GaONPs, DEN, DEN+Cu-CTAB, DEN+GaO-NPs and DEN+Cu-CTAB+GaO-NPs. Histopathological examination of liver and biochemical parameters such as liver function markers, oxidative stress-antioxidants markers, tumor makers, apoptosis makers were studied. Results: Results obtained from in vitro study revealed that Cu-CTAB+GaO-NPs and GaO-NPs affect the cell viability of HepG-2 cancer cell with IC50 0.2 μg/ml and 360 μg/ml, respectively. Cu-CTAB+GaO-NPs exerted an antiproliferative effect in experimental rat models of HCC, as demonstrated both histologically, since it facilitated the tissue recovery of the damaged liver, and biochemically as showed by the reduction of liver function markers (ALT & AST), oxidative stress markers (MDA) and tumor makers (AFP,TGF-β1,α-L-Fucosidase); while antioxidants markers (SOD), apoptosis markers (caspase-3 mRNA) and araginase activity were elevated in DEN+Cu-CTAB, DEN+GaO-NPs and DEN+Cu-CTAB+GaO-NPs groups when compared to DEN group. Conclusion: The present study demonstrated that both Cu-CTAB alone and/or combined with GaO-NPs exerted cytotoxic effects against DEN-induced HCC, which would in turn, speculate a possible therapeutic role of the novel Cu-CTAB+GaO-NPs compound.

A Systematic Review of the Anti-inflammatory Effects of Gallium Compounds

BACKGROUND

Inflammation is an essential response provided by the immune system, ensuring the survival during microbial infection, tissue injury and other noxious conditions. However, prolonged inflammatory processes are often associated with severe side effects on health.

OBJECTIVE

This systematic review aimed to provide the evidence in the literature of the preclinical and human anti-inflammatory activity of gallium compounds from 2000 to 2019 focused on elucidating the mechanisms involved in the inflammatory process.

METHODS

Seven bibliographical databases were consulted (PubMed, Medline, ScienceDirect, Scopus, Springer, Web of Science, and EBSCOhost). The selection of appropriate publications and writing of this systematic review were based on the guidelines mentioned in the PRISMA statement. Moreover, the assessment of the methodological quality of the selected studies was also performed.

RESULTS

From a total of 3018 studies, 16 studies were included in this paper based on our eligibility criteria, which showed promising and consistent results.

CONCLUSION

Further research concerning specific inflammatory conditions is required.

Mesoporous zirconia surfaces with anti-biofilm properties for dental implants

Cytocompatible bioactive surface treatments conferring antibacterial properties to osseointegrated dental implants are highly requested to prevent bacteria-related peri-implantitis. Here we focus on a newly designed family of mesoporous coatings based on zirconia (ZrO₂) microstructure doped with gallium (Ga), exploiting its antibacterial and pro-osseo-integrative properties. The ZrO₂films were obtained via sol-gel synthesis route using Pluronic F127 as templating agent, while Ga doping was gained by introducing gallium nitrate hydrate. Chemical characterization by means of x-ray photoelectron spectroscopy and glow discharge optical emission spectroscopy confirmed the effective incorporation of Ga. Then, coatings morphological and structural analysis were carried out by transmission electron microscopy and selected area electron diffraction unveiling an effective stabilization of both the mesoporous structure and the tetragonal ZrO₂phase. Specimens' cytocompatibility was confirmed towards gingival fibroblast and osteoblasts progenitors cultivated directly onto the coatings showing comparable metabolic activity and morphology in respect to controls cultivated on polystyrene. The presence of Ga significantly reduced the metabolic activity of the adhered oral pathogensPorphyromonas gingivalisandAggregatibacter actinomycetemcomitansin comparison to untreated bulk zirconia (p< 0.05); on the opposite, Ga ions did not significantly reduce the metabolism of the oral commensalStreptococcus salivarius(p> 0.05) thus suggesting for a selective anti-pathogens activity. Finally, the coatings' ability to preserve cells from bacterial infection was proved in a co-culture method where cells and bacteria were cultivated in the same environment: the presence of Ga determined a significant reduction of the bacteria viability while allowing at the same time for cells proliferation. In conclusion, the here developed coatings not only demonstrated to satisfy the requested antibacterial and cytocompatibility properties, but also being promising candidates for the improvement of implantable devices in the field of implant dentistry.

Lanthanum, Gallium and their Impact on Oxidative Stress

The role metals play in living organisms is well established and subject to extensive research. Some of them participate in electron-exchange reactions. Such reactions cause generation of free radicals that can adversely impact biological systems, as a result of oxidative stress. The impact of 'non-biological' metals on oxidative stress is also a worthy pursuit due to the crucial role they play in modern civilization. Lanthanides (Ln) are widely used in modern technology. As a result, human exposure to them is increasing. They have a number of established medical applications and are being extensively researched for their potential antiviral, anticancer and anti-inflammatory properties. The present review focuses on lanthanum (La) and its impact on oxidative stress. Another metal, widely used in modern high-tech is gallium (Ga). In some respects, it shows certain similarities to La, therefore it is a subject of the present review as well. Both metals exhibit ionic mimicry which allows them to specifically target malignant cells, initiating apoptosis that makes their simple salts and coordination complexes promising candidates for future anticancer agents.

Gallium disrupts bacterial iron metabolism and has therapeutic effects in mice and humans with lung infections

The lack of new antibiotics is among the most critical challenges facing medicine. The problem is particularly acute for Gram-negative bacteria. An unconventional antibiotic strategy is to target bacterial nutrition and metabolism. The metal gallium can disrupt bacterial iron metabolism because it substitutes for iron when taken up by bacteria. We investigated the antibiotic activity of gallium ex vivo, in a mouse model of airway infection, and in a phase 1 clinical trial in individuals with cystic fibrosis (CF) and chronic Pseudomonas aeruginosa airway infections. Our results show that micromolar concentrations of gallium inhibited P. aeruginosa growth in sputum samples from patients with CF. Ex vivo experiments indicated that gallium inhibited key iron-dependent bacterial enzymes and increased bacterial sensitivity to oxidants. Furthermore, gallium resistance developed slowly, its activity was synergistic with certain antibiotics, and gallium did not diminish the antibacterial activity of host macrophages. Systemic gallium treatment showed antibiotic activity in murine lung infections. In addition, systemic gallium treatment improved lung function in people with CF and chronic P. aeruginosa lung infection in a preliminary phase 1 clinical trial. These findings raise the possibility that human infections could be treated by targeting iron metabolism or other nutritional vulnerabilities of bacterial pathogens.

The therapeutic potential of iron-targeting gallium compounds in human disease: From basic research to clinical application

Gallium, group IIIa metal, shares certain chemical characteristics with iron which enable it to function as an iron mimetic that can disrupt iron-dependent tumor cell growth. Gallium may also display antimicrobial activity by disrupting iron homeostasis in certain bacteria and fungi. Gallium's action on iron homeostasis leads to inhibition of ribonucleotide reductase, mitochondrial function, and changes in proteins of iron transport and storage. In addition, gallium induces an increase in mitochondrial reactive oxygen species in cells which triggers downstream upregulation of metallothionein and hemoxygenase-1. Early clinical trials evaluated the efficacy of the simple gallium salts, gallium nitrate and gallium chloride. However, newer gallium-ligands such as Tris(8-quinolinolato)gallium(III) (KP46) and gallium maltolate have been developed and are undergoing clinical evaluation. Additional gallium-ligands that demonstrate antitumor activity in preclinical studies have emerged. Their mechanisms of action and their spectrum of antitumor activity may extend beyond the earlier generations of gallium compounds and warrant further investigation. This review will focus on the evolution and potential of gallium-based therapeutics.

Medical applications and toxicities of gallium compounds

Over the past two to three decades, gallium compounds have gained importance in the fields of medicine and electronics. In clinical medicine, radioactive gallium and stable gallium nitrate are used as diagnostic and therapeutic agents in cancer and disorders of calcium and bone metabolism. In addition, gallium compounds have displayed anti-inflammatory and immunosuppressive activity in animal models of human disease while more recent studies have shown that gallium compounds may function as antimicrobial agents against certain pathogens. In a totally different realm, the chemical properties of gallium arsenide have led to its use in the semiconductor industry. Gallium compounds, whether used medically or in the electronics field, have toxicities. Patients receiving gallium nitrate for the treatment of various diseases may benefit from such therapy, but knowledge of the therapeutic index of this drug is necessary to avoid clinical toxicities. Animals exposed to gallium arsenide display toxicities in certain organ systems suggesting that environmental risks may exist for individuals exposed to this compound in the workplace. Although the arsenic moiety of gallium arsenide appears to be mainly responsible for its pulmonary toxicity, gallium may contribute to some of the detrimental effects in other organs. The use of older and newer gallium compounds in clinical medicine may be advanced by a better understanding of their mechanisms of action, drug resistance, pharmacology, and side-effects. This review will discuss the medical applications of gallium and its mechanisms of action, the newer gallium compounds and future directions for development, and the toxicities of gallium compounds in current use.

Elimination of arthritis pain and inflammation for over 2years with a single 90min, topical 14% gallium nitrate treatment: Case reports and review of actions of gallium III

Arthritis is inflammation in a joint often with joint damage, usually accompanied by pain, swelling and stiffness, resulting from infection, trauma, degenerative changes, metabolic disturbances, autoimmune or other causes. It occurs in various forms, including rheumatoid arthritis, osteoarthritis, bacterial arthritis and gout. Gallium III can inhibit the production of inflammatory cytokines, such as IL-1beta, produced by macrophage-like cells in vitro. A dose-dependent inhibition of IL-1beta and TPA stimulated MMP activity by gallium nitrate at increasing concentrations occurs, demonstrating that gallium nitrate can be a useful modulator of inflammation in arthritis. Gallium III is an inhibitor of bone resorption and is an effective treatment for hypercalcemia. Gallium III has been reported to be effective in the treatment of mycobacterium butycicum-induced arthritis in rats by antagonism of iron III. Long-term elimination of pain from arthritis by gallium III was first observed in horses primarily being treated for navicular disease. Several people treating their horses with gallium nitrate coincidentally found that arthritis pain in their fingers ended and did not return after soaking their hands in 14% gallium nitrate solution. Therefore, the severely arthritic hands of a 60-year-old woman were topically treated with a 14% aqueous solution of gallium nitrate for 90 min. Pain and inflammation from rheumatoid arthritis diminished rapidly, and neither pain nor inflammation returned during the following 2 years from that single treatment. A 61-year-old woman who had osteoarthritis in her left knee, shoulders and wrists was treated orally with 50 ml of a 1% gallium nitrate solution (120 mg elemental gallium) daily using a two week on and two week off protocol, resulting in almost total elimination of pain while on gallium nitrate, while pain partially returned during the two week off periods. Treatment of frozen shoulder with topical 40% gallium nitrate for 120 min resulted in greatly reduced pain and crepitus almost immediately with complete restoration of range of motion, with pain remaining essentially absent for over 1 year. Mechanisms of action are hypothesized to include anti-inflammatory, bone density improvements, antibacterial, anti-iron III and anti-aluminum III effects. Proper use of gallium III may be effective in terminating pain and inflammation of arthritis for years, often with a single treatment.

Lessons from animal models of vasculitis

Vasculitis can occur as a primary disease or as a secondary manifestation of either another illness or a type-III hypersensitivity response to a foreign antigen. Over the past four decades, a number of animal models of vasculitis have been described. These models have served as important tools for enhancing our understanding of the basic mechanisms underlying the pathogenesis of vasculitis. In addition, animal models have made possible the preclinical testing of new therapeutic agents. Animal models of vasculitis can be broadly classified into two types--those that are experimentally induced and those that occur spontaneously. Vasculitis can be experimentally induced in animals through the stimulation of a type-III hypersensitivity response to a variety of foreign antigens, by viral or bacterial infection of vascular cells and the immune response to that infection, or by the in-vivo administration of antineutrophil cytoplasmic antibodies, estrogen, or mercuric chloride (HgCl(2)). Systemic vasculitis spontaneously develops in several strains of mice and rats. This paper reviews the current state of knowledge of several animal models of vasculitis and the lessons that have been learned from them.

Gallium nitrate suppresses the production of nitric oxide and liver damage in a murine model of LPS-induced septic shock

The efficacy of gallium (Ga) nitrate was examined in a murine model of sepsis. Male Balb/c mice (6-8 weeks) were randomized into 3 groups: 1) vehicle-treated controls 2) mice with sepsis induced by treatment with 0.3 mg i.v. of Propionibacterium acnes followed one week later by 0.01 microg lipopolysaccharide (LPS) and 10 mg of D-galactosamine (GalN) 3) mice with sepsis injected with 45 mg/kg s.c. of gallium nitrate (calculated as elemental Ga) 24 hours prior to LPS/GalN. Two hours after LPS/GalN or vehicle, plasma concentrations of tumor necrosis factor (TNF-alpha) in groups 1, 2 and 3 were 54+/-31 (n=6), 21,390+/-5139 (n=4), and 21,909+/-943 (n=5) pg/ml, respectively. After 6 hours, plasma concentrations of gamma interferon (IFN-gamma) were <10 (n=8), 4771+/-1078 (n=6), and 1622+/-531 (n=15) pg/ml, respectively, and of nitrate/nitrite (products of nitric oxide) were 64+/-8 (n=7), 146+/-18 (n=8), and 57+/-8 (n=15) microM. At 18 hours, serum chemistries were; SGOT 171+/-46 (n=13), 10,986+/-3062 (n=7), and 1078+/-549 (n=8) IU/L; SGPT 165+/-59, 17,214+/-4340, and 2088+/-1097 IU/L; and total bilirubin 0.2+/-0.0, 0.9+/-0.4, and 0.2+/-0.0 mg/dl for groups 1, 2, and 3 respectively. Blinded histologic evaluation of livers at 18 hours revealed inflammatory infiltrate scores (x [range], 0=none, 1=minimal, 2=mild, 3=moderate, and 4=severe) of 0.1 [0-1] (n=8), 3.0 [2-4] (n=15), and 2.0 [0-3] (n=10), and necrosis scores of 0.0, 2.8 [0-4], and 0.9 [0-4]. Although Ga did not affect production of TNF-alpha, it ameliorated hepatocellular injury and protected against necrosis. Based on this model of sepsis, Ga may have a role in treating the human disease.