Introduction of Zinc-salt Fixation for Effective Detection of Immune Cell-related Markers by Immunohistochemistry

Tumor microenvironmental determinants of high-risk DCIS progression

Ductal carcinoma in situ (DCIS) constitutes an array of morphologically recognized intraductal neoplasms in the mammary ductal tree defined by an increased risk for subsequent invasive carcinomas at or near the site of biopsy detection. However, only 15-45% of untreated DCIS cases progress to invasive cancer, so understanding mechanisms that prevent progression is key to avoid overtreatment and provides a basis for alternative therapies and prevention. This study was designed to characterize the tumor microenvironment and molecular profile of high-risk DCIS that grew to a large size but remained as DCIS. All patients had DCIS lesions >5cm in size with at least one additional high-risk feature: young age (<45 years), high nuclear grade, hormone receptor negativity, HER2 positivity, the presence of comedonecrosis, or a palpable mass. The tumor immune microenvironment was characterized using multiplex immunofluorescence to identify immune cells and their spatial relationships within the ducts and stroma. Gene copy number analysis and whole exome DNA sequencing identified the mutational burden and driver mutations, and quantitative whole-transcriptome/gene expression analyses were performed. There was no association between the percent of the DCIS genome characterized by copy number variants (CNAs) and recurrence events (DCIS or invasive). Mutations, especially missense mutations, in the breast cancer driver genes PIK3CA and TP53 were common in this high-risk DCIS cohort (47% of evaluated lesions). Tumor infiltrating lymphocyte (TIL) density was higher in DCIS lesions with TP53 mutations (p=0.0079) compared to wildtype lesions, but not in lesions with PIK3CA mutations (p=0.44). Immune infiltrates were negatively associated with hormone receptor status and positively associated with HER2 expression. High levels of CD3+CD8- T cells were associated with good outcomes with respect to any subsequent recurrence (DCIS or invasive cancer), whereas high levels of CD3+Foxp3+ Treg cells were associated with poor outcomes. Spatial proximity analyses of immune cells and tumor cells demonstrated that close proximity of T cells with tumor cells was associated with good outcomes with respect to any recurrence as well as invasive recurrences. Interestingly, we found that myoepithelial continuity (distance between myoepithelial cells surrounding the involved ducts) was significantly lower in DCIS lesions compared to normal tissue (p=0.0002) or to atypical ductal hyperplasia (p=0.011). Gene set enrichment analysis identified several immune pathways associated with low myoepithelial continuity and a low myoepithelial continuity score was associated with better outcomes, suggesting that gaps in the myoepithelial layer may allow access/interactions between immune infiltrates and tumor cells. Our study demonstrates the immune microenvironment of DCIS, in particular the spatial proximity of tumor cells and T cells, and myoepithelial continuity are important determinants for progression of disease.

CXCL9/10-engineered dendritic cells promote T cell activation and enhance immune checkpoint blockade for lung cancer

Immune checkpoint blockade (ICB) with PD-1/PD-L1 inhibition has revolutionized the treatment of non-small cell lung cancer (NSCLC). Durable responses, however, are observed only in a subpopulation of patients. Defective antigen presentation and an immunosuppressive tumor microenvironment (TME) can lead to deficient T cell recruitment and ICB resistance. We evaluate intratumoral (IT) vaccination with CXCL9- and CXCL10-engineered dendritic cells (CXCL9/10-DC) as a strategy to overcome resistance. IT CXCL9/10-DC leads to enhanced T cell infiltration and activation in the TME and tumor inhibition in murine NSCLC models. The antitumor efficacy of IT CXCL9/10-DC is dependent on CD4+ and CD8+ T cells, as well as CXCR3-dependent T cell trafficking from the lymph node. IT CXCL9/10-DC, in combination with ICB, overcomes resistance and establishes systemic tumor-specific immunity in murine models. These studies provide a mechanistic understanding of CXCL9/10-DC-mediated host immune activation and support clinical translation of IT CXCL9/10-DC to augment ICB efficacy in NSCLC.

Evaluation of immunological adjuvant activities of saponin rich fraction from the fruits of Asparagus adscendens Roxb. with less adverse reactions

The hemolytic activity, in vitro as well as in vivo toxicity, and immunomodulatory potential of saponins-rich fraction of Asparagus adscendens Roxb. fruit (AA-SRF) have been assessed in this study in order to explore AA-SRF as an alternative safer adjuvant to standard Quil-A saponin. The AA-SRF showed lower hemolytic activity (HD₅₀ = 301.01 ± 1.63 µg/ml) than Quil-A (HD₅₀ = 17.15 ± 2.12 µg/ml). The sulforhodamine B assay also revealed that AA-SRF was less toxic to VERO cells (IC₅₀≥200 ± 4.32 µg/ml) than Quil-A (IC₅₀ = 60 ± 2.78 µg/ml). The AA-SRF did not lead to mortality in mice up to 1.6 mg and was much safer than Quil-A for in vivo use. Conversely, mice were subcutaneously immunized with OVA 100 μg alone or along with Alum (200 μg) or Quil-A (10 μg) or AA-SRF (50 μg/100 μg/200 μg) on days 0 and 14. The AA-SRF at 100 μg dose best supported the LPS/Con A primed splenocyte proliferation activity, elevated the serum OVA-specific total IgG antibody, IL-12, CD4 titer and upsurged CD3/CD19 expression in spleen as well as lymph node sections which in turn advocated its adjuvant potential. Thus, AA-SRF can be further studied for use as a safe alternative adjuvant in vaccines.

Protocol for investigating tertiary lymphoid structures in human and murine fixed tissue sections using Opal™-TSA multiplex immunohistochemistry

Tertiary lymphoid structures (TLSs) are ectopic lymphoid aggregates that can develop within or adjacent to tumors, but protocols that can accurately identify and characterize TLSs are lacking. Here, we present a protocol for the in situ interrogation and characterization of TLSs in human and murine tissue sections using Opal™-tyramide signal amplification multiplex immunohistochemistry. This protocol enables simultaneous detection of up to 7 markers (6 antigens and a DAPI counterstain). We also describe a grading system to identify immature and mature TLSs.

Immunohistochemical Characterization of Immune System Cells in Lymphoid Organs from Roe and Fallow Deer

Simple Summary

Diseases emerging from wildlife represent a growing public health issue. Cervids share many pathogens with domestic species and humans, representing useful spontaneous models to evaluate host-pathogen balance. Histology and immunohistochemistry can help in fully understanding the pathogenesis of infection in these species, but few studies have been conducted to characterize immune cell markers. This study highlights that lymphocytes and macrophagic subsets in roe and fallow deer lymphoid tissue can be identified by a panel of commercial antibodies developed against humans. A description of the main immune cell distribution was provided. These results may support future investigations on immune cell response and pathogenesis in roe and fallow deer diseases.

Abstract

Roe and Fallow deer are common wild ruminants widely distributed in Italy. Infectious diseases of these species can potentially pose health risks to domestic animals and humans. However, few studies have been conducted in which immune system cells in these species were phenotyped. The aims of this study were to determine the cross-reactivity of a wide anti-human panel of commercial antibodies on formalin-fixed and paraffin-embedded (FFPE) samples and to describe the distribution of roe and fallow deer main immune cell subsets in the lymph nodes and spleen. Twenty retromandibular lymph nodes (RLNs) and spleen samples were collected from 10 roe deer and 10 fallow deer and were tested by a panel of 12 commercial anti-human antibodies. The CD79a, CD20, CD3, Iba-1, MAC387, and AM-3K antibodies were successfully labeled cells in cervine tissue, while the Foxp3 and the CD68 did not show suitable immunostaining. This study supplies the first immunohistochemical description of immune cell subpopulations in non-pathological spleen and RLNs from roe and fallow deer and provides an easily repeatable manual IHC protocol to immunolocalize cervine B-, T-cells, and macrophages subsets in FFPE tissue samples.

Development of a Multiplex Immunohistochemistry Workflow to Investigate the Immune Microenvironment in Mouse Models of Inflammatory Bowel Disease and Colon Cancer

Multiplex immunohistochemistry (mIHC) enables simultaneous staining of multiple immune markers on a single tissue section. Mounting studies have demonstrated the versatility of mIHC in evaluating immune infiltrates in different diseases and the tumour microenvironment (TME). However, the majority of published studies are limited to the analysis of human patient samples. Performing mIHC on formalin-fixed paraffin-embedded (FFPE) mouse tissues, particularly with sensitive antigens, remain challenging. The aim of our study was to develop a robust and reproducible protocol to uncover the immune landscape in mouse FFPE tissues. Effective antibody stripping while maintaining sensitivity to antigens and tissue adhesion to the glass slide is critical in developing an mIHC panel to allow successive rounds of staining. Thus, we identified a highly efficient stripping method that preserves signal intensity and antigenicity to allow multiple rounds of staining. We subsequently optimised an mIHC workflow with antibodies specific against CD4, CD8α, FOXP3 and B220 to identify distinct T and B cell populations on mouse FFPE tissues. Lastly, the application of this mIHC panel was validated in a mouse model of inflammatory bowel cancer, two allograft mouse models of spontaneous colon adenocarcinoma and a sporadic mouse model of colon cancer. Together, these demonstrate the utility of the aforementioned protocol in establishing the quantity and spatial localisation of immune cells in different pathological tissues.

Preparation of Ex Vivo Rodent Phantoms for Developing, Testing, and Training MR Imaging of the Kidney and Other Organs

Here we describe a simple and inexpensive protocol for preparing ex vivo rodent phantoms for use in MR imaging studies. The experimental animals are perfused and fixed with formaldehyde, and then wrapped with gauze and sealed with liquid latex. This yields a phantom that preserves all organs in situ, and which avoids the need to keep fixed animals and organs in containers that have dimensions very different from living animals. This is especially important for loading in MR detectors, and specifically the RF coils, they are usually used with. The phantom can be safely stored and conveniently reused, and can provide MR scientists with a realistic phantom with which to establish protocols in preparation for preclinical in vivo studies-for renal, brain, and body imaging. The phantom also serves as an ideal teaching tool, for trainees learning how to perform preclinical MRI investigations of the kidney and other target organs, while avoiding the need for handling living animals, and reducing the total number of animals required.This protocol chapter is part of the PARENCHIMA initiative "MRI Biomarkers for CKD " (CA16103), a community-driven Action of the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers.

Murine Model of Thermal Burn Injury for Evaluating Protein Therapeutics Derived from Viruses

In vivo wound healing models are predictive preclinical tests for therapeutics that enhance skin repair or limit scarring. Large animals, such as swine, heal in a manner similar to humans, but testing is impractical and expensive. Experiments in mice are more economic, but may be less translatable as this species heals primarily through contraction, not by the processes of epithelialization and granulation tissue formation as seen in human wounds. Here, we describe a murine model of thermal burn injury that closely mimics human healing, resulting in a large, hypertrophic-like scar. This practical, reproducible model is ideal for testing promising wound-healing therapies, such as virus-derived growth factors and immune-modulatory proteins.

FTY720 reactivates cryptococcal granulomas in mice through S1P receptor 3 on macrophages

FTY720 is a treatment for relapsing remitting multiple sclerosis (MS). It is an analog of sphingosine-1-phosphate (S1P) and targets S1P receptors 1, 3, 4, and 5. Recent reports indicate an association between long-term exposure to FTY720 and cases of cryptococcal infection. Here, we studied the effect of FTY720 and its derivative, BAF312, which only target S1P receptors 1 and 5, in a mouse model of cryptococcal infection. We found that treatment with FTY720, but not with BAF312, led to decreased survival and increased organ burden in mouse cryptococcal granulomas. Both FTY720 and BAF312 caused a profound CD4+ and CD8+ T cell depletion in blood and lungs but only treatment with FTY720 led to cryptococcal reactivation. Treatment with FTY720, but not with BAF312, was associated with disorganization of macrophages and with M2 polarization at the granuloma site. In a cell system, FTY720 decreased phagocytosis and production of reactive oxygen species by macrophages, a phenotype recapitulated in the S1pr3-/- knockout macrophages. Our results suggest that FTY720 reactivates cryptococcosis from the granuloma through a S1P receptor 3-mediated mechanism and support the rationale for development of more-specific receptor modulators for therapeutic use of MS.

[Analysis of interference criteria for the validation of a method file: HPS staining after fixation with zinc-formalin in comparison to fixation with the classical 4% buffered formalin solution]

INTRODUCTION

The department of neuropathology of Sainte-Anne Hospital uses zinc-formalin as the fixative agent for its samples. No publication referenced in Pubmed has proven the validity of this fixative agent. In the context of the accreditation of our standard staining (HPS for Hemalun-Phloxin-Saffron), we started a file for the validation of this method in which the fixative agent constitutes an « interfering » substance which can modify the quality of the technique. The aim of this study was to prove that the use of zinc-formalin as a fixative agent is as suitable as the fixation with 4 % buffered formalin.

MATERIALS AND METHODS

A cohort of samples fixed by zinc-formalin and by 4 % buffered formalin was performed on fresh samples, then cut and stained by HPS. The slides were interpreted by three pathologists (one of them was outside our centre)  ``blind '' to the fixative agent and they evaluated four criteria (general quality of the staining, components of the extracellular matrix, cytoplasmic details, and nuclear details) and scored them (from 0 to 3) according to the Association française en assurance qualité (AFAQAP) recommendations.

RESULTS

The cohort included 43 samples. The results of the analysis showed that for samples fixed by zinc-formalin, three of the four criteria obtained significantly a better score than the samples fixed by classical formalin.

DISCUSSION AND CONCLUSIONS

Our results show that the zinc-formalin fixative does not constitute an  ``interfering '' agent for the quality of the HPS staining for neuropathological samples.

Dose Fractionation During Puberty Is More Detrimental to Mammary Gland Development Than an Equivalent Acute Dose of Radiation Exposure

PURPOSE

Computed tomographic (CT) scans in adolescents have increased dramatically in recent years. However, the effects of cumulative low-dose exposures on the development of radiation sensitive organs, such as the mammary gland, is unknown. The purpose of this work was to define the effects of dose rate on mammary organ formation during puberty, an especially sensitive window in mammary development. We used a fractionated low-dose x-ray exposure to mimic multiple higher dose CT scans, and we hypothesized that fractionated exposure would have less of an effect on the number of mammary gland defects compared with an acute exposure.

METHODS AND MATERIALS

Female mice were subjected to fractionated low-dose x-ray exposure (10 cGy/d for 5 days), acute x-ray exposure (1 × 50 cGy), or sham exposure. As the wide genetic diversity in humans can play a role in a person's response to irradiation, 2 genetically diverse mouse strains differing in radiation sensitivity (BALB/c-sensitive; C57BL/6-resistant) were used to investigate the role of genetic background on the magnitude of the effect.

RESULTS

Unexpectedly, our data reveal that multiple low-dose exposures produce greater immune and mammary defects for weeks after exposure compared with controls. The most pronounced defects being increased ductal branching in both strains and a greater percentage of terminal end buds in the BALB/c strain of mice exposed to fractionated radiation compared with sham. Radiation-induced defects near the terminal end bud were also increased in both strains.

CONCLUSIONS

The findings suggest that fractionated low-dose exposures are potentially more damaging to organ development compared with an equivalent, single acute exposure and that genetic background is an important parameter modifying the severity of these effects.

Basal and Infectious Enteritis in Broilers Under the I See Inside Methodology: A Chronological Evaluation

Recently, the inflammation of the intestinal mucosa has been related to many diseases in humans and animals. The concept of Microscopic Enteritis (ME) used in human pathology through the Marsh classification system has no counter-part in veterinary medicine. In poultry science, the I See Inside (ISI) methodology, unlike the current linear measures of villi and crypts, generates possibilities to describe and understand the avian ME. Through specific parameters, graded from 0 to 3, the model links proliferative and/or inflammatory reactions in the intestinal layers to some loss in performance. Herein, two trials were conducted in order to describe the development of ME through the ISI methodology in chickens challenged or not with Eimeria spp. and Clostridium perfringens. In each trial, a total of 64 birds were divided in 2 treatments with 4 replicates containing 8 birds each: non-challenged (NCH) and challenged (CH) through gavage with an Eimeria spp. vaccine at 1 day of age and 10⁸ CFU/mL of Clostridium perfringens administered at 10, 11, and 12 days of age. At 7, 14, 21, and 28 days of age birds were euthanized and samples of ileum and liver were collected for ISI evaluation, cytokines and presence of macrophages, CD4+ and CD8+ cell. The results allowed the description of the avian Microscopic Enteritis and of its two basic components: a basal enteritis (BE) in NCH broilers, over which the infectious enteritis is developed in CH birds. In addition, the chronology of ME translated by the ISI methodology parameters were associated to losses in zootechnical performance.

Tracking Modified Vaccinia Virus Ankara in the Chicken Embryo: In Vivo Tropism and Pathogenesis of Egg Infections

The Modified Vaccinia virus Ankara (MVA) is a highly attenuated vaccinia virus serving as a promising vector vaccine platform to develop vaccines against infectious diseases. In contrast to the well-established replication deficiency and safety of MVA in mammals, much less is known about MVA infection in avian hosts. Here, we used a recombinant MVA expressing fluorescent reporter proteins under transcriptional control of specific viral early and late promoters to study in vivo tropism, distribution, and pathogenesis of MVA infections in embryonated chicken eggs. The chorioallantoic membrane (CAM) of embryonated chicken eggs was inoculated with recombinant MVA, MVA or phosphate-buffered saline. The infection was analyzed by fluorescence microscopy, histology, immunohistochemistry, and virus titration of embryonic tissues. After infection of the CAM, MVA spread to internal and external embryonic tissues with the liver as a major target organ. Macrophages and hematopoietic cells were identified as primary target cells of MVA infection and may be involved in virus spread. Increasing doses of MVA did not result in increased lesion severity or embryonic death. Despite MVA generalization to embryonic tissues, the CAM seems to be the major site of MVA replication. The absence of considerable organ lesions and MVA-associated mortality highlights an excellent safety profile of MVA in chicken hosts.

Partial Depletion of Peripheral M1 Macrophages Reverses Motor Deficits in MPTP-Treated Mouse by Suppressing Neuroinflammation and Dopaminergic Neurodegeneration

Background: Neuroinflammation plays an important role in the pathogenesis of Parkinson's disease (PD). Inflammatory cytokines in the peripheral immune system can induce neuroinflammation in central nervous system (CNS). Whether the peripheral immune system is involved in PD is unclear. The present study investigated the contribution of the peripheral immune system to the neuronal loss in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP) model of PD.

Methods: MPTP was intraperitoneally injected into mice to generate a PD model. Mice received clodronate liposomes every 3 days to deplete peripheral macrophages. The percentages of macrophages were measured by flow cytometry at 1, 3, and 7 days after MPTP injection. Neurobehavioral parameters, protein expression, inflammatory cytokines release, and microglia activation were measured by the open field test, western blotting, quantitative polymerase chain reaction (qPCR), and immunofluorescence staining, respectively at 7 days after MPTP injection.

Results: Our study revealed that intraperitoneal injection of MPTP could increase peripheral M1 macrophages levels. It also can induce T cells infiltration and cytokine release. Depletion of M1 macrophages by clodronate liposomes suppressed these inflammatory effects and blunted the loss of TH+ nigral neurons and functional impairments caused by MPTP.

Conclusion: Our results indicated the critical role of M1 macrophages in the pathogenesis of PD and proposed inhibition of M1 macrophages as a promising therapeutic approach for neurodegeneration.

Aging Mouse Models Reveal Complex Tumor-Microenvironment Interactions in Cancer Progression

Mouse models and genetically engineered mouse models (GEMM) are essential experimental tools for the understanding molecular mechanisms within complex biological systems. GEMM are especially useful for inferencing phenocopy information to genetic human diseases such as breast cancer. Human breast cancer modeling in mice most commonly employs mammary epithelial-specific promoters to investigate gene function(s) and, in particular, putative oncogenes. Models are specifically useful in the mammary epithelial cell in the context of the complete mammary gland environment. Gene targeted knockout mice including conditional targeting to specific mammary cells can reveal developmental defects in mammary organogenesis and demonstrate the importance of putative tumor suppressor genes. Some of these models demonstrate a non-traditional type of tumor suppression which involves interplay between the tumor susceptible cell and its host/environment. These GEMM help to reveal the processes of cancer progression beyond those intrinsic to cancer cells. Furthermore, the, analysis of mouse models requires appropriate consideration of mouse strain, background, and environmental factors. In this review, we compare aging-related factors in mouse models for breast cancer. We introduce databases of GEMM attributes and colony functional variations.

Toll-like receptor 3 (TLR3) promotes the resolution of Chlamydia muridarum genital tract infection in congenic C57BL/6N mice

Chlamydia trachomatis urogenital serovars primarily replicate in epithelial cells lining the reproductive tract. Epithelial cells recognize Chlamydia through cell surface and cytosolic receptors, and/or endosomal innate receptors such as Toll-like receptors (TLRs). Activation of these receptors triggers both innate and adaptive immune mechanisms that are required for chlamydial clearance, but are also responsible for the immunopathology in the reproductive tract. We previously demonstrated that Chlamydia muridarum (Cm) induces IFN-β in oviduct epithelial cells (OE) in a TLR3-dependent manner, and that the synthesis of several cytokines and chemokines are diminished in Cm-challenged OE derived from TLR3-/- 129S1 mice. Furthermore, our in vitro studies showed that Cm replication in TLR3-/- OE is more efficient than in wild-type OE. Because TLR3 modulates the release inflammatory mediators involved in host defense during Cm infection, we hypothesized that TLR3 plays a protective role against Cm-induced genital tract pathology in congenic C57BL/6N mice. Using the Cm mouse model for human Chlamydia genital tract infections, we demonstrated that TLR3-/- mice had increased Cm shedding during early and mid-stage genital infection. In early stage infection, TLR3-/- mice showed a diminished synthesis of IFN-β, IL-1β, and IL-6, but enhanced production of IL-10, TNF-α, and IFN-γ. In mid-stage infection, TLR3-/- mice exhibited significantly enhanced lymphocytic endometritis and salpingitis than wild-type mice. These lymphocytes were predominantly scattered along the endometrial stroma and the associated smooth muscle, and the lamina propria supporting the oviducts. Surprisingly, our data show that CD4+ T-cells are significantly enhanced in the genital tract TLR3-/- mice during mid-stage Chlamydial infection. In late-stage infections, both mouse strains developed hydrosalpinx; however, the extent of hydrosalpinx was more severe in TLR3-/- mice. Together, these data suggest that TLR3 promotes the clearance of Cm during early and mid-stages of genital tract infection, and that loss of TLR3 is detrimental in the development hydrosalpinx.

Pathobiology of the 129:Stat1 -/- mouse model of human age-related ER-positive breast cancer with an immune infiltrate-excluded phenotype

Background

Stat1 gene-targeted knockout mice (129S6/SvEvTac-Stat1^tm1Rds) develop estrogen receptor-positive (ER⁺), luminal-type mammary carcinomas at an advanced age. There is evidence for both host environment as well as tumor cell-intrinsic mechanisms to initiate tumorigenesis in this model. In this report, we summarize details of the systemic and mammary pathology at preneoplastic and tumor-bearing time points. In addition, we investigate tumor progression in the 129:Stat1^−/− host compared with wild-type 129/SvEv, and we describe the immune cell reaction to the tumors.

Methods

Mice housed and treated according to National Institutes of Health guidelines and Institutional Animal Care and Use Committee-approved methods were evaluated by histopathology, and their tissues were subjected to immunohistochemistry with computer-assisted quantitative image analysis. Tumor cell culture and conditioned media from cell culture were used to perform macrophage (RAW264.7) cell migration assays, including the 129:Stat1^−/−-derived SSM2 cells as well as control Met1 and NDL tumor cells and EpH4 normal cells.

Results

Tumorigenesis in 129:Stat1^−/− originates from a population of FoxA1⁺ large oval pale cells that initially appear and accumulate along the mammary ducts in segments or regions of the gland prior to giving rise to mammary intraepithelial neoplasias. Progression to invasive carcinoma is accompanied by a marked local stromal and immune cell response composed predominantly of T cells and macrophages. In conditioned media experiments, cells derived from 129:Stat1^−/− tumors secrete both chemoattractant and chemoinhibitory factors, with greater attraction in the extracellular vesicular fraction and inhibition in the soluble fraction. The result appears to be recruitment of the immune reaction to the periphery of the tumor, with exclusion of immune cell infiltration into the tumor.

Conclusions

129:Stat1^−/− is a unique model for studying the critical origins and risk reduction strategies in age-related ER⁺ breast cancer. In addition, it can be used in preclinical trials of hormonal and targeted therapies as well as immunotherapies.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-017-0892-8) contains supplementary material, which is available to authorized users.

Approaches to Evaluate Lung Inflammation in Translational Research

Inflammation is a common feature in several types of lung disease and is a frequent end point to validate lung disease models, evaluate genetic or environmental impact on disease severity, or test the efficacy of new therapies. Questions relevant to a study should be defined during experimental design and techniques selected to specifically address these scientific queries. In this review, the authors focus primarily on the breadth of techniques to evaluate lung inflammation that have both clinical and preclinical applications. Stratification of approaches to assess lung inflammation can diminish weaknesses inherent to each technique, provide data validation, and increase the reproducibility of a study. Specialized techniques (eg, imaging, pathology) often require experienced personnel to collect, evaluate, and interpret the data; these experts should be active contributors to the research team through reporting of the data. Scoring of tissue lesions is a useful method to transform observational pathologic data into semiquantitative or quantitative data for statistical analysis and enhanced rigor. Each technique to evaluate lung inflammation has advantages and limitations; understanding these parameters can help identify approaches that best complement one another to increase the rigor and translational significance of data.

Methods of Immunohistochemistry and Immunofluorescence: Converting Invisible to Visible

Observing changes in pathophysiological tissue samples often relies on immunohistochemical or immunofluorescence analysis. These techniques show target microanatomy by visualizing marker molecules on cells and their microenvironment. Here, we describe the "pros and cons" in each method, along with alternative procedures and the suggested imaging equipment.