Copper complexes as a source of redox active MRI contrast agents

The study reports an advance in designing copper-based redox sensing MRI contrast agents. Although the data demonstrate that copper(II) complexes are not able to compete with lanthanoids species in terms of contrast, the redox-dependent switch between diamagnetic copper(I) and paramagnetic copper(II) yields a novel redox-sensitive contrast moiety with potential for reversibility

Oncogenic Properties of Apoptotic Tumor Cells in Aggressive B Cell Lymphoma

BACKGROUND: Cells undergoing apoptosis are known to modulate their tissue microenvironments. By acting on phagocytes, notably macrophages, apoptotic cells inhibit immunological and inflammatory responses and promote trophic signaling pathways. Paradoxically, because of their potential to cause death of tumor cells and thereby militate against malignant disease progression, both apoptosis and tumor-associated macrophages (TAMs) are often associated with poor prognosis in cancer. We hypothesized that, in progression of malignant disease, constitutive loss of a fraction of the tumor cell population through apoptosis could yield tumor-promoting effects. RESULTS: Here, we demonstrate that apoptotic tumor cells promote coordinated tumor growth, angiogenesis, and accumulation of TAMs in aggressive B cell lymphomas. Through unbiased "in situ transcriptomics" analysis-gene expression profiling of laser-captured TAMs to establish their activation signature in situ-we show that these cells are activated to signal via multiple tumor-promoting reparatory, trophic, angiogenic, tissue remodeling, and anti-inflammatory pathways. Our results also suggest that apoptotic lymphoma cells help drive this signature. Furthermore, we demonstrate that, upon induction of apoptosis, lymphoma cells not only activate expression of the tumor-promoting matrix metalloproteinases MMP2 and MMP12 in macrophages but also express and process these MMPs directly. Finally, using a model of malignant melanoma, we show that the oncogenic potential of apoptotic tumor cells extends beyond lymphoma. CONCLUSIONS: In addition to its profound tumor-suppressive role, apoptosis can potentiate cancer progression. These results have important implications for understanding the fundamental biology of cell death, its roles in malignant disease, and the broader consequences of apoptosis-inducing anti-cancer therapy

The development of copper complexes as medical imaging agents

Studies building on existing research into the development of in vivo oxidant sensors which could be used as magnetic resonance (MR) imaging agents for the early detection of oxidative stress have been carried out. A series of N₂S₂ copper macrocyclic systems have been synthesised building on previous studies. The compounds have been modified at various positions to further enhance the suitability of these species as magnetic resonance imaging agents. The modifications include the introduction of oxo and sulfur based pendant arms at the nitrogen donor atoms, the introduction electron withdrawing and electron donating groups at various positions on the ring and the use of softer donor atoms to produce an S₄ and S₃N system. The stability and suitability of the complexes were challenged using a number of techniques including spectrophotometric titrations, cyclic voltammetry and T₁ relation NMR. The stability of the copper centre of the macrocycles was challenged with a biologically relevant sequestration agent (bovine serum albumin). It was found that 5 coordinate copper macrocycles are the most stable. The electrochemical reversibility of the complexes was tested using cyclic voltammetry to identify which compounds were capable of redox reversibility. A sulfur based pendant arm complex (compound 52) showed promise. Studies using ascorbate and hypochlorite demonstrate that this compound will survive chemical reduction and re-oxidation returning an acceptable percentage reversibility. To assess the potential of all of the complexes for use as imaging agents, the effect of the complexes on the T₁ relaxation time was tested over a range of concentrations. This was compared with a Gd-DTPA control and original parent complex (compound 2). The modifications made very little difference to the T₁ relaxation times. Although the relaxivity is low the studies indicates that the modified complexes may have some viability for use and warrant further investigation.Studies building on existing research into the development of in vivo oxidant sensors which could be used as magnetic resonance (MR) imaging agents for the early detection of oxidative stress have been carried out. A series of N₂S₂ copper macrocyclic systems have been synthesised building on previous studies. The compounds have been modified at various positions to further enhance the suitability of these species as magnetic resonance imaging agents. The modifications include the introduction of oxo and sulfur based pendant arms at the nitrogen donor atoms, the introduction electron withdrawing and electron donating groups at various positions on the ring and the use of softer donor atoms to produce an S₄ and S₃N system. The stability and suitability of the complexes were challenged using a number of techniques including spectrophotometric titrations, cyclic voltammetry and T₁ relation NMR. The stability of the copper centre of the macrocycles was challenged with a biologically relevant sequestration agent (bovine serum albumin). It was found that 5 coordinate copper macrocycles are the most stable. The electrochemical reversibility of the complexes was tested using cyclic voltammetry to identify which compounds were capable of redox reversibility. A sulfur based pendant arm complex (compound 52) showed promise. Studies using ascorbate and hypochlorite demonstrate that this compound will survive chemical reduction and re-oxidation returning an acceptable percentage reversibility. To assess the potential of all of the complexes for use as imaging agents, the effect of the complexes on the T₁ relaxation time was tested over a range of concentrations. This was compared with a Gd-DTPA control and original parent complex (compound 2). The modifications made very little difference to the T₁ relaxation times. Although the relaxivity is low the studies indicates that the modified complexes may have some viability for use and warrant further investigation

Reactions of copper macrocycles with antioxidants and HOCl : potential for biological redox sensing

A series of simple copper N2S2 macrocycles were examined for their potential as biological redox sensors, following previous characterization of their redox potentials and crystal structures. The divalent species were reduced by glutathione or ascorbate at a biologically relevant pH in aqueous buffer. A less efficient reduction was also achieved by vitamin E in DMSO. Oxidation of the corresponding univalent copper species by sodium hypochlorite resulted in only partial (~65 %) recovery of the divalent form. This was concluded to be due to competition between metal oxidation and ligand oxidation, which is believed to contribute to macrocycle demetallation. Electrospray mass spectrometry confirmed that ligand oxidation had occurred. Moreover, the macrocyclic complexes could be demetallated by incubation with EDTA and bovine serum albumin, demonstrating that they would be inappropriate for use in biological systems. The susceptibility to oxidation and demetallation was hypothesized to be due to oxidation of the secondary amines. Consequently these were modified to incorporate additional oxygen donor atoms. This modification led to greater resistance to demetallation and ligand oxidation, providing a better platform for further development of copper macrocycles as redox sensors for use in biological systems

Serological responses to SARS-CoV-2 following non-hospitalised infection: clinical and ethnodemographic features associated with the magnitude of the antibody response.

OBJECTIVE To determine clinical and ethnodemographic correlates of serological responses against the SARS-CoV-2 spike glycoprotein following mild-to-moderate COVID-19. DESIGN A retrospective cohort study of healthcare workers who had self-isolated due to COVID-19. SETTING University Hospitals Birmingham NHS Foundation Trust, UK (UHBFT). PARTICIPANTS 956 healthcare workers were recruited by open invitation via UHBFT trust email and social media between 27 April 2020 and the 8 June 2020. INTERVENTION Participants volunteered a venous blood sample that was tested for the presence of anti-SARS-CoV-2 spike glycoprotein antibodies. Results were interpreted in the context of the symptoms of their original illness and ethnodemographic variables. RESULTS Using an assay that simultaneously measures the combined IgG, IgA and IgM response against the spike glycoprotein (IgGAM), the overall seroprevalence within this cohort was 46.2% (n=442/956). The seroprevalence of immunoglobulin isotypes was 36.3%, 18.7% and 8.1% for IgG, IgA and IgM, respectively. IgGAM identified serological responses in 40.6% (n=52/128) of symptomatic individuals who reported a negative SARS-CoV-2 PCR test. Increasing age, non-white ethnicity and obesity were independently associated with greater IgG antibody response against the spike glycoprotein. Self-reported fever and fatigue were associated with greater IgG and IgA responses against the spike glycoprotein. The combination of fever and/or cough and/or anosmia had a positive predictive value of 92.3% for seropositivity in self-isolating individuals a time when Wuhan strain SARS-CoV-2 was predominant. CONCLUSIONS AND RELEVANCE Assays employing combined antibody detection demonstrate enhanced seroepidemiological sensitivity and can detect prior viral exposure even when PCR swabs have been negative. We demonstrate an association between known ethnodemographic risk factors associated with mortality from COVID-19 and the magnitude of serological responses in mild-to-moderate disease