Imaging of cytotoxic antiviral immunity while considering the 3R principle of animal research

Simulated skin model for in vitro evaluation of insertion performance of microneedles: design, development, and application verification

Microneedles, as a new efficient and safe transdermal drug delivery technology, has a wide range of applications in drug delivery, vaccination, medical cosmetology, and diagnostics. The degree of microneedles penetration into the skin determines the reliability of the delivery dose, but its evaluation is not yet well-established, which is one of the major constraints in the commercialization of microneedles. In this paper, a novel visual simulated skin model was developed with reference to the physical properties of real skin. The simulated skin model was well-designed and its prescription was optimized to make the thickness, hardness, elasticity, and other parameters close to those of real skin. It not only meets the need to assess the degree of insertion of microneedles but also provides a visual observation of the insertion state of microneedles.

PD-1 knockout on cytotoxic primary murine CD8+ T cells improves their motility in retrovirus infected mice

Cytotoxic T lymphocyte (CTL) motility is an important feature of effective CTL responses and is impaired when CTLs become exhausted, e.g. during chronic retroviral infections. A prominent T cell exhaustion marker is programmed cell death protein 1 (PD-1) and antibodies against the interaction of PD-1 and PD-ligand 1 (PD-L1) are known to improve CTL functions. However, antibody blockade affects all PD-1/PD-L1-expressing cell types, thus, the observed effects cannot be attributed selectively to CTLs. To overcome this problem, we performed CRISPR/Cas9 based knockout of the PD-1 coding gene PDCD1 in naïve Friend Retrovirus (FV)-specific CTLs. We transferred 1,000 of these cells into mice where they proliferated upon FV-infection. Using intravital two-photon microscopy we visualized CTL motility in the bone marrow and evaluated cytotoxic molecule expression by flow cytometry. Knockout of PDCD1 improved the CTL motility at 14 days post infection and enhanced the expression of cytotoxicity markers. Our data show the potential of genetic tuning of naive antiviral CTLs and might be relevant for future designs of improved T cell-mediated therapies.

Regulatory T cells suppress the motility of cytotoxic T cells in Friend retrovirus-infected mice

Antiviral immunity often requires CD8+ cytotoxic T lymphocytes (CTLs) that actively migrate and search for virus-infected targets. Regulatory T cells (Tregs) have been shown to suppress CTL responses, but it is not known whether this is also mediated by effects on CTL motility. Here, we used intravital 2-photon microscopy in the Friend retrovirus (FV) mouse model to define the impact of Tregs on CTL motility throughout the course of acute infection. Virus-specific CTLs were very motile and had frequent short contacts with target cells at their peak cytotoxic activity. However, when Tregs were activated and expanded in late-acute FV infection, CTLs became significantly less motile and contacts with target cells were prolonged. This phenotype was associated with development of functional CTL exhaustion. Tregs had direct contacts with CTLs in vivo and, importantly, their experimental depletion restored CTL motility. Our findings identify an effect of Tregs on CTL motility as part of their mechanism of functional impairment in chronic viral infections. Future studies must address the underlying molecular mechanisms.

Tissue optical clearing and 3D imaging of virus infections

Imaging pathogens within 3D environment of biological tissues provides spatial information about their localization and interactions with the host. Technological advances in fluorescence microscopy and 3D image analysis now permit visualization and quantification of pathogens directly in large tissue volumes and in great detail. In recent years large volume imaging became an important tool in virology research helping to understand the properties of viruses and the host response to infection. In this chapter we give a review of fluorescence microscopy modalities and tissue optical clearing methods used for large volume tissue imaging. A summary of recent applications for virus research is provided with particular emphasis on studies using light sheet fluorescence microscopy. We describe the challenges and approaches for volumetric image analysis. Practical examples of volumetric imaging implemented in virology laboratories and addressing specialized research questions, such as virus tropism and immune host response are described. We conclude with an overview of the emerging technologies and their potential for virus research.

Embryo-Engineered Nonhuman Primate Models: Progress and Gap to Translational Medicine

Animal models of human diseases are vital in better understanding the mechanism of pathogenesis and essential for evaluating and validating potential therapeutic interventions. As close relatives of humans, nonhuman primates (NHPs) play an increasingly indispensable role in advancing translational medicine research. In this review, we summarized the progress of NHP models generated by embryo engineering, analyzed their unique advantages in mimicking clinical patients, and discussed the remaining gap between basic research of NHP models to translational medicine.

Bifidobacterium animalis F1-7 in combination with konjac glucomannan improves constipation in mice via humoral transport

Probiotics and natural products can promote humoral transport and effectively relieve intestinal motility. This study investigated the effects of probiotics in combination with konjac glucomannan (KGM) and an aqueous extract of Prunus persica on constipation. The growth promotion effect of these natural products on probiotics was investigated using co-culture in vitro. The combined effect of probiotics and natural products on constipation was observed in mice. The tryptophan, tryptamine and short-chain fatty acid levels were determined using enzyme-linked immunosorbent assay, reverse-phase high-performance liquid chromatography, and gas chromatography. The key genes and proteins involved in humoral transport were identified using real-time polymerase chain reaction, western blotting and fluorescence immunoassay. KGM promoted the growth of Bifidobacterium animalis F1-7 in vitro, and a mixture of KGM and B. animalis F1-7 effectively promoted defaecation in mice, increased the faecal water content, shortened the defaecation time and improved the gastrointestinal transit rate. In mice, the KGM + F1-7 mixture reduced the tryptophan level and increased the levels of tryptamine, acetic acid, propionic acid, butyric acid and valeric acid. In addition, the KGM + F1-7 mixture effectively increased the mRNA level of 5-HT₄-G-protein-coupled receptors (5-HT₄GPCR)/mucins-2 (MUC-2) and reduced the level of aquaporins (AQP₃); furthermore, it upregulated the protein level of 5-HT₄GPCR/MUC-2 and downregulated the protein level of AQP₃. These findings indicated that the KGM + F1-7 mixture effectively improved intestinal motility and alleviated constipation through humoral transport-related pathways.

Next-generation imaging of the skeletal system and its blood supply

Bone is organized in a hierarchical 3D architecture. Traditionally, analysis of the skeletal system was based on bone mass assessment by radiographic methods or on the examination of bone structure by 2D histological sections. Advanced imaging technologies and big data analysis now enable the unprecedented examination of bone and provide new insights into its 3D macrostructure and microstructure. These technologies comprise ex vivo and in vivo methods including high-resolution computed tomography (CT), synchrotron-based imaging, X-ray microscopy, ultra-high-field magnetic resonance imaging (MRI), light-sheet fluorescence microscopy, confocal and intravital two-photon imaging. In concert, these techniques have been used to detect and quantify a novel vascular system of trans-cortical vessels in bone. Furthermore, structures such as the lacunar network, which harbours and connects osteocytes, become accessible for 3D imaging and quantification using these methods. Next-generation imaging of the skeletal system and its blood supply are anticipated to contribute to an entirely new understanding of bone tissue composition and function, from macroscale to nanoscale, in health and disease. These insights could provide the basis for early detection and precision-type intervention of bone disorders in the future.

From chemotherapy to biological therapy: A review of novel concepts to reduce the side effects of systemic cancer treatment (Review)

The side effects of systemic chemotherapy used to treat cancer are often severe. For decades, oncologists have focused on treating the tumor, which may result in damage to the tumor-bearing host and its immune system. Recently, much attention has been paid to the immune system of patients and its activation via biological therapies. Biological therapies, including immunotherapy and oncolytic virus (OV) therapy, are often more physiological and well tolerated. The present review elucidated how these therapies work and why these therapies may be better tolerated: i) In contrast to chemotherapy, immunotherapies induce a memory function of the adaptive immunity system; ii) immunotherapies aim to specifically activate the immune system against cancer; side effects are low due to immune tolerance mechanisms, which maintain the integrity of the body in the presence of B and T lymphocytes with their antigen-receptor specificities and; iii) the type I interferon response, which is evoked by OVs, is an ancient innate immune defense system. Biological and physiological therapies, which support the immune system, may therefore benefit cancer treatment. The present review focused on immunotherapy, with the aim of reducing side effects and increasing long-lasting efficacy in cancer therapy.