In Vivo Assimilation of CuS, Iron Oxide and Iron Oxide@CuS Nanoparticles in Mice: A 6-Month Follow-Up Study

Nanoparticles (NPs) are at the leading edge of nanomedicine, and determining their biosafety remains a mandatory precondition for biomedical applications. Herein, we explore the bioassimilation of copper sulfide NPs reported as powerful photo-responsive anticancer therapeutic agents. The nanoparticles investigated present a hollow shell morphology, that can be left empty (CuS NPs) or be filled with an iron oxide flower-like core (iron oxide@CuS NPs), and are compared with the iron oxide nanoparticles only (iron oxide NPs). CuS, iron oxide@CuS and iron oxide NPs were injected in 6-week-old mice, at doses coherent with an antitumoral treatment. Cu and Fe were quantified in the liver, spleen, kidneys, and lungs over 6 months, including the control animals, thus providing endogenous Cu and Fe levels in the first months after animal birth. After intravenous NPs administration, 77.0 ± 3.9% of the mass of Cu injected, and 78.6 ± 3.8% of the mass of Fe, were detected in the liver. In the spleen, we found 3.3 ± 0.6% of the injected Cu and 3.8 ± 0.6% for the Fe. No negative impact was observed on organ weight, nor on Cu or Fe homeostasis in the long term. The mass of the two metals returned to the control values within three months, a result that was confirmed by transmission electron microscopy and histology images. This bioassimilation with no negative impact comforts the possible translation of these nanomaterials into clinical practice.

The pro-fibrotic and senescence phenotype of old lung fibroblasts is reversed or ameliorated by genetic and pharmacological manipulation of Slc7a11 expression

Increased senescence and expression of pro-fibrotic genes in old lung fibroblasts contribute to disrepair responses. We reported that primary lung fibroblasts from old mice have lower expression and activity of the cystine transporter Slc7a11/xCT than cells from young mice, resulting in changes in both the intracellular and extracellular redox environments. This study examines the hypothesis that low Slc7a11 expression in old lung fibroblasts promotes senescence and pro-fibrotic gene expression. The levels of mRNA and protein of Slc7a11, senescence markers, and pro-fibrotic genes were measured in primary fibroblasts from the lungs of old (24 months) and young (3 months) mice. In addition, the effects of genetic and pharmacological manipulation of Slc7a11 were investigated. We found that decreased expression of Slc7a11 in old cells was associated with elevated markers of senescence (p21, p16, p53 and b-galactosidase) and increased expression of pro-fibrotic genes (Tgfb1, Smad3, Acta2, Fn1, Col1a1 and Col5a1). Silencing of Slc7a11 in young cells replicated the aging phenotype, whereas overexpression of Slc7a11 in old cells decreased expression of senescence and pro-fibrotic genes. Young cells were induced to express the senescence and pro-fibrotic phenotype by sulfasalazine, an Slc7a11 inhibitor, whereas treatment of old cells with sulforaphane, an Slc7a11 inducer, decreased senescence without affecting pro-fibrotic genes. Like aging cells, idiopathic pulmonary fibrosis fibroblasts show decreased Slc7a11 expression and increased pro-fibrotic markers. In short, old lung fibroblasts manifest a pro-fibrotic and senescence phenotype that is modulated by genetic or pharmacological manipulation of Slc7a11.

Neuronal Loss of the Glutamate Transporter GLT-1 Promotes Excitotoxic Injury in the Hippocampus

GLT-1, the major glutamate transporter in the mammalian central nervous system, is expressed in presynaptic terminals that use glutamate as a neurotransmitter, in addition to astrocytes. It is widely assumed that glutamate homeostasis is regulated primarily by glutamate transporters expressed in astrocytes, leaving the function of GLT-1 in neurons relatively unexplored. We generated conditional GLT-1 knockout (KO) mouse lines to understand the cell-specific functions of GLT-1. We found that stimulus-evoked field extracellular postsynaptic potentials (fEPSPs) recorded in the CA1 region of the hippocampus were normal in the astrocytic GLT-1 KO but were reduced and often absent in the neuronal GLT-1 KO at 40 weeks. The failure of fEPSP generation in the neuronal GLT-1 KO was also observed in slices from 20 weeks old mice but not consistently from 10 weeks old mice. Using an extracellular FRET-based glutamate sensor, we found no difference in stimulus-evoked glutamate accumulation in the neuronal GLT-1 KO, suggesting a postsynaptic cause of the transmission failure. We hypothesized that excitotoxicity underlies the failure of functional recovery of slices from the neuronal GLT-1 KO. Consistent with this hypothesis, the non-competitive NMDA receptor antagonist MK801, when present in the ACSF during the recovery period following cutting of slices, promoted full restoration of fEPSP generation. The inclusion of an enzymatic glutamate scavenging system in the ACSF conferred partial protection. Excitotoxicity might be due to excess release or accumulation of excitatory amino acids, or to metabolic perturbation resulting in increased vulnerability to NMDA receptor activation. Previous studies have demonstrated a defect in the utilization of glutamate by synaptic mitochondria and aspartate production in the synGLT-1 KO in vivo, and we found evidence for similar metabolic perturbations in the slice preparation. In addition, mitochondrial cristae density was higher in synaptic mitochondria in the CA1 region in 20–25 weeks old synGLT-1 KO mice in the CA1 region, suggesting compensation for loss of axon terminal GLT-1 by increased mitochondrial efficiency. These data suggest that GLT-1 expressed in presynaptic terminals serves an important role in the regulation of vulnerability to excitotoxicity, and this regulation may be related to the metabolic role of GLT-1 expressed in glutamatergic axon terminals.

Aging Aggravates Cachexia in Tumor-Bearing Mice

Background: Cancer is primarily a disease of high age in humans, yet most mouse studies on cancer cachexia are conducted using young adolescent mice. Given that metabolism and muscle function change with age, we hypothesized that aging may affect cachexia progression in mouse models. Methods: We compare tumor and cachexia development in young and old mice of three different strains (C57BL/6J, C57BL/6N, BALB/c) and with two different tumor cell lines (Lewis Lung Cancer, Colon26). Tumor size, body and organ weights, fiber cross-sectional area, circulating cachexia biomarkers, and molecular markers of muscle atrophy and adipose tissue wasting are shown. We correlate inflammatory markers and body weight dependent on age in patients with cancer. Results: We note fundamental differences between mouse strains. Aging aggravates weight loss in LLC-injected C57BL/6J mice, drives it in C57BL/6N mice, and does not influence weight loss in C26-injected BALB/c mice. Glucose tolerance is unchanged in cachectic young and old mice. The stress marker GDF15 is elevated in cachectic BALB/c mice independent of age and increased in old C57BL/6N and J mice. Inflammatory markers correlate significantly with weight loss only in young mice and patients. Conclusions: Aging affects cachexia development and progression in mice in a strain-dependent manner and influences the inflammatory profile in both mice and patients. Age is an important factor to consider for future cachexia studies.

In Vitro Propagation of XXY Undifferentiated Mouse Spermatogonia: Model for Fertility Preservation in Klinefelter Syndrome Patients

Klinefelter syndrome (KS) is characterized by a masculine phenotype, supernumerary sex chromosomes (usually XXY), and spermatogonial stem cell (SSC) loss in their early life. Affecting 1 out of every 650 males born, KS is the most common genetic cause of male infertility, and new fertility preservation strategies are critically important for these patients. In this study, testes from 41, XXY prepubertal (3-day-old) mice were frozen-thawed. Isolated testicular cells were cultured and characterized by qPCR, digital PCR, and flow cytometry analyses. We demonstrated that SSCs survived and were able to be propagated with testicular somatic cells in culture for up to 120 days. DNA fluorescent in situ hybridization (FISH) showed the presence of XXY spermatogonia at the beginning of the culture and a variety of propagated XY, XX, and XXY spermatogonia at the end of the culture. These data provide the first evidence that an extra sex chromosome was lost during innate SSC culture, a crucial finding in treating KS patients for preserving and propagating SSCs for future sperm production, either in vitro or in vivo. This in vitro propagation system can be translated to clinical fertility preservation for KS patients.

SARS-CoV-2 Variants of Concern Infect the Respiratory Tract and Induce Inflammatory Response in Wild-Type Laboratory Mice

The emergence of new severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants of concern pose a major threat to public health, due to possible enhanced virulence, transmissibility and immune escape. These variants may also adapt to new hosts, in part through mutations in the spike protein. In this study, we evaluated the infectivity and pathogenicity of SARS-CoV-2 variants of concern in wild-type C57BL/6 mice. Six-week-old mice were inoculated intranasally with a representative virus from the original B.1 lineage, or the emerging B.1.1.7 and B.1.351 lineages. We also infected a group of mice with a mouse-adapted SARS-CoV-2 (MA10). Viral load and mRNA levels of multiple cytokines and chemokines were analyzed in the lung tissues on day 3 after infection. Our data show that unlike the B.1 virus, the B.1.1.7 and B.1.351 viruses are capable of infecting C57BL/6 mice and replicating at high concentrations in the lungs. The B.1.351 virus replicated to higher titers in the lungs compared with the B.1.1.7 and MA10 viruses. The levels of cytokines (IL-6, TNF-α, IL-1β) and chemokine (CCL2) were upregulated in response to the B.1.1.7 and B.1.351 infection in the lungs. In addition, robust expression of viral nucleocapsid protein and histopathological changes were detected in the lungs of B.1.351-infected mice. Overall, these data indicate a greater potential for infectivity and adaptation to new hosts by emerging SARS-CoV-2 variants.

Influence of age and ways of treatment in the parasitemia in mice infected with Trypanosoma cruzi treated with high potency biotherapy

Introduction: The infection of mice by Trypanosoma cruzi is well known, making this a good model for understanding the effect of highly diluted medications. Mice of different ages show different responses to biotherapic T. cruzi [1]. Other data from our laboratory using biotherapic treatment at low potencies show that long lasting treatment has a better effect in mice infected with T. cruzi. However, the use of high potency biotherapics in mice of different ages infected with T. cruzi has not been analysed yet. Aim: To evaluate the effect of different ways of treatment using biotherapic 200 DH T. cruzi in the evolution of the curve of parasitemia of mice of different ages infected with T. cruzi. Materials and methods: A blind randomized controlled trial was performed using 107 swiss male mice, aged 28, 35 and 56 days, divided into groups: CONTROL(C) – mice aged 28(C28), 38(C38) and 56(C56) days, treated with 7% water-alcohol solution diluted with water (1mL/100mL); ONE DAY(OD) – mice aged 28(OD28), 38(OD38) and 56(OD56) days, treated with highly diluted medication 200 DH T. cruzi in a single dose, diluted in water (10mL/100mL); EVERY DAY(ED) – mice aged 28(ED28), 38(ED38) and 56(ED56) days, treated with highly diluted medication 200DH T.cruzi until the end of the experiment, diluted in water(1mL/100mL). Amber bottle was used and the water was changed every two days. The groups were infected with strain Y-T. cruzi, intraperitoneal,1400 blood trypomastigotes. Medicines were handled according to the Brazilian Homeopathic Pharmacopoeia [2], with microbiological testing according to RDC n° 67 and in vivo biological risk. We compared the parasitemia curve and total parasitemia, determined daily counting of the parasites [3], obtained using the tests Kruskal-Wallis and Wald-Wolfowitz, Statistica 8.0, 5% significance. Approved by the Ethics Committee for Animal Experimentation/ UEM - 030/2008. Results: The animal age and the ways of treatment used influenced the evolution of the parasitemia curve. This evolution was different among different ages, and the youngest mice of the control group had higher averages of parasitemia ( C28=1.4x106/mL; C38= 1.3 x106/mL and C56=1.0x106/mL ) (fig1). This evolution was not observed in the groups treated daily, in which 56 day-old mice presented a higher parasitemia compared to the other groups ( ED28= 1.3x106/mL; ED38=0.9x106/mL and ED56=1.2x106/mL )(fig1b). For animals treated with a single dose, the energetic stimulus provided by biotherapic caused homogeneity of biological behavior, with significant elevation of parasitemia ( OD28=1.8x106/mL; OD38=1.3x106/mL and OD56=1.5 x106/mL) (fig1c). Likewise, the single dose treatment invariably resulted in an increase of parasitemia when compared to other treatments within the same age group (fig1d-f). The treatment performed daily in animals aged 28 and 38 days showed a decrease in parasitemia (fig1d-f). For 56 day-old mice this fall was not observed (fig1f). The meaning of this finding should be better explored considering the physiological maturity versus the vital energy of mice of different ages. Conclusion: The age and the ways of treatment used are important factors to be considered when using a highly diluted medication. The clinical use of these results in humans, should take into consideration the allometric system of medication dosage which takes into account the metabolic rate of each organism.

Liposomal Encapsulation of Polysaccharides (LEPS) as an Effective Vaccine Strategy to Protect Aged Hosts Against S. pneumoniae Infection

Despite the availability of licensed vaccines, pneumococcal disease caused by the bacteria Streptococcus pneumoniae (pneumococcus), remains a serious infectious disease threat globally. Disease manifestations include pneumonia, bacteremia, and meningitis, resulting in over a million deaths annually. Pneumococcal disease disproportionally impacts older adults aged ≥65 years. Interventions are complicated through a combination of complex disease progression and 100 different bacterial capsular polysaccharide serotypes. This has made it challenging to develop a broad vaccine against S. pneumoniae, with current options utilizing capsular polysaccharides as the primary antigenic content. However, current vaccines are substantially less effective in protecting the elderly. We previously developed a Liposomal Encapsulation of Polysaccharides (LEPS) vaccine platform, designed around limitations of current pneumococcal vaccines, that allowed the non-covalent coupling of polysaccharide and protein antigen content and protected young hosts against pneumococcal infection in murine models. In this study, we modified the formulation to make it more economical and tested the novel LEPS vaccine in aged hosts. We found that in young mice (2–3 months), LEPS elicited comparable responses to the pneumococcal conjugate vaccine Prevnar-13. Further, LEPS immunization of old mice (18–22 months) induced comparable antibody levels and improved antibody function compared to Prevnar-13. Importantly, LEPS protected old mice against both invasive and lung localized pneumococcal infections. In summary, LEPS is an alternative and effective vaccine strategy that protects aged hosts against different manifestations of pneumococcal disease.

Dynamic structural cell responses in the thymus to acute injury, regeneration, and age

The thymus, the primary site of T cell development, is extremely sensitive to insult but also harbors tremendous capacity for repair. Using single cell sequencing of thymic structural cells, as well as functional and structural analyses, we revealed distinct regenerative programs by endothelial and mesenchymal subsets after injury that stimulated epithelial repair; the compartment primarily supporting T cell development. Thymic function not only declined over lifespan, contributing to immune aging, but the capacity of the thymus to regenerate after damage also declined in old mice. This could be attributed to an inability of the old microenvironment to induce reparative programs; leading to reduced ability to restore tissue structure and function. These findings provide a detailed framework for the response of structural cells to aging and acute damage, which could have considerable implications for our understanding of aging immunity and recovery from treatments such as chemotherapy and bone marrow transplant.

Link between aging and atheroprotection in Mif-deficient atherosclerotic mice

Atherosclerosis is a lipid-triggered chronic inflammatory condition of our arteries and the main underlying pathology of myocardial infarction and stroke. Pathogenesis is age-dependent, but the mechanistic links between disease progression, age, and atherogenic cytokines and chemokines are incompletely understood. Here, we studied the chemokine-like inflammatory cytokine macrophage migration inhibitory factor (MIF) in atherogenic Apoe-/- mice across different stages of aging and cholesterol-rich high-fat diet (HFD). MIF promotes atherosclerosis by mediating atherogenic monocyte and T-cell recruitment, amplifying lesional inflammation, and suppressing atheroprotective B-cell responses. However, age-related links between atherogenesis and MIF and its role in advanced atherosclerosis in aged mice have not been systematically explored. We compared effects of global Mif-gene deficiency in 30-, 42-, and 48-week-old Apoe-/- mice on HFD for 24, 36, or 42 weeks, respectively, and in 52-week-old mice on a 6-week HFD. While a regio-specific atheroprotective phenotype of Mif-deficiency was observed in the 30/24-week-old group, atheroprotection was not detected in the 48/42- and 52/6-week-old groups, suggesting that atheroprotection afforded by global Mif-gene deletion differs across aging stages and atherogenic diet duration. We identify a combination of mechanisms that could explain this phenotype: i) Mif-deficiency promotes lesional Trem2+ macrophage numbers in younger but not aged mice; ii) Mif-deficiency favors formation of lymphocyte-rich stage-I/II ATLOs in younger mice but ATLO numbers equalize with those in Apoe-/- controls in the older mice; and iii) plasma anti-oxLDL-IgM antibody levels are decreased in aged Mif-deficient mice. Of note, these three markers (Trem2+ macrophages, ATLOs, anti-oxLDL-IgM antibodies) have been previously linked to atheroprotection. Together, our study thus suggests that regio-specific atheroprotection due to global Mif-gene deficiency in atherogenic Apoe-/- mice is lost upon advanced aging and identifies mechanisms that could explain this phenotype shift. These observations may have implications for translational MIF-directed strategies.