Differentiation of malignant B-lymphoma cells from normal and activated T-cell populations by their intrinsic autofluorescence

Fundus Autofluorescence in Posterior and Panuveitis-An Under-Estimated Imaging Technique: A Review and Case Series

Fundus autofluorescence (FAF) is a prompt and non-invasive imaging modality helpful in detecting pathological abnormalities within the retina and the choroid. This narrative review and case series provides an overview on the current application of FAF in posterior and panuveitis. The literature was reviewed for articles on lesion characteristics on FAF of specific posterior and panuveitis entities as well as benefits and limitations of FAF for diagnosing and monitoring disease. FAF characteristics are described for non-infectious and infectious uveitis forms as well as masquerade syndromes. Dependent on the uveitis entity, FAF is of diagnostic value in detecting disease and following the clinical course. Currently available FAF modalities which differ in excitation wavelengths can provide different pathological insights depending on disease entity and activity. Further studies on the comparison of FAF modalities and their individual value for uveitis diagnosis and monitoring are warranted.

Label-free macrophage phenotype classification using machine learning methods

Macrophages are heterogeneous innate immune cells that are functionally shaped by their surrounding microenvironment. Diverse macrophage populations have multifaceted differences related to their morphology, metabolism, expressed markers, and functions, where the identification of the different phenotypes is of an utmost importance in modelling immune response. While expressed markers are the most used signature to classify phenotypes, multiple reports indicate that macrophage morphology and autofluorescence are also valuable clues that can be used in the identification process. In this work, we investigated macrophage autofluorescence as a distinct feature for classifying six different macrophage phenotypes, namely: M0, M1, M2a, M2b, M2c, and M2d. The identification was based on extracted signals from multi-channel/multi-wavelength flow cytometer. To achieve the identification, we constructed a dataset containing 152,438 cell events each having a response vector of 45 optical signals fingerprint. Based on this dataset, we applied different supervised machine learning methods to detect phenotype specific fingerprint from the response vector, where the fully connected neural network architecture provided the highest classification accuracy of 75.8% for the six phenotypes compared simultaneously. Furthermore, by restricting the number of phenotypes in the experiment, the proposed framework produces higher classification accuracies, averaging 92.0%, 91.9%, 84.2%, and 80.4% for a pool of two, three, four, five phenotypes, respectively. These results indicate the potential of the intrinsic autofluorescence for classifying macrophage phenotypes, with the proposed method being quick, simple, and cost-effective way to accelerate the discovery of macrophage phenotypical diversity.

AutoSpill is a principled framework that simplifies the analysis of multichromatic flow cytometry data

Compensating in flow cytometry is an unavoidable challenge in the data analysis of fluorescence-based flow cytometry. Even the advent of spectral cytometry cannot circumvent the spillover problem, with spectral unmixing an intrinsic part of such systems. The calculation of spillover coefficients from single-color controls has remained essentially unchanged since its inception, and is increasingly limited in its ability to deal with high-parameter flow cytometry. Here, we present AutoSpill, an alternative method for calculating spillover coefficients. The approach combines automated gating of cells, calculation of an initial spillover matrix based on robust linear regression, and iterative refinement to reduce error. Moreover, autofluorescence can be compensated out, by processing it as an endogenous dye in an unstained control. AutoSpill uses single-color controls and is compatible with common flow cytometry software. AutoSpill allows simpler and more robust workflows, while reducing the magnitude of compensation errors in high-parameter flow cytometry.

Fluorescence lifetime shifts of NAD(P)H during apoptosis measured by time-resolved flow cytometry

Autofluorescence from the intracellular metabolite, NAD(P)H, is a biomarker that is widely used and known to reliably screen and report metabolic activity as well as metabolic fluctuations within cells. As a ubiquitous endogenous fluorophore, NAD(P)H has a unique rate of fluorescence decay that is altered when bound to coenzymes. In this work we measure the shift in the fluorescence decay, or average fluorescence lifetime (1–3 ns), of NAD(P)H and correlate this shift to changes in metabolism that cells undergo during apoptosis. Our measurements are made with a flow cytometer designed specifically for fluorescence lifetime acquisition within the ultraviolet to violet spectrum. Our methods involved culture, treatment, and preparation of cells for cytometry and microscopy measurements. The evaluation we performed included observations and quantification of the changes in endogenous emission owing to the induction of apoptosis as well as changes in the decay kinetics of the emission measured by flow cytometry. Shifts in NAD(P)H fluorescence lifetime were observed as early as 15 min post‐treatment with an apoptosis inducing agent. Results also include a phasor analysis to evaluate free to bound ratios of NAD(P)H at different time points. We defined the free to bound ratios as the ratio of ‘short‐to‐long’ (S/L) fluorescence lifetime, where S/L was found to consistently decrease with an increase in apoptosis. With a quantitative framework such as phasor analysis, the short and long lifetime components of NAD(P)H can be used to map the cycling of free and bound NAD(P)H during the early‐to‐late stages of apoptosis. The combination of lifetime screening and phasor analyses provides the first step in high throughput metabolic profiling of single cells and can be leveraged for screening and sorting for a range of applications in biomedicine. © 2018 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of International Society for Advancement of Cytometry.

The manifestation of optical centers in UV-Vis absorption and luminescence spectra of white blood human cells

A white blood human cells spectral investigation is presented. The aim of this series of experiments was to obtain and analyze the absorption and luminescence (fluorescence and phosphorescence) spectra at room temperature and at 78 K of newly isolated white blood human cells and their organelles. As a result the optical centers and possible biochemical components that form the studied spectra where identified. Also the differences between the spectra of abnormal cells (B-cell chronic lymphocytic leukemia BCLL) and normal ones were studied for the whole cells and individual organelles.

Endogenous light scattering as an optical signature of circulating tumor cell clusters

Circulating tumor cell clusters (CTCCs) are significantly more likely to form metastases than single tumor cells. We demonstrate the potential of backscatter-based flow cytometry (BSFC) to detect unique light scattering signatures of CTCCs in the blood of mice orthotopically implanted with breast cancer cells and treated with an anti-ADAM8 or a control antibody. Based on scattering detected at 405, 488, and 633 nm from blood samples flowing through microfluidic devices, we identified 14 CTCCs with large scattering peak widths and intensities, whose presence correlated strongly with metastasis. These initial studies demonstrate the potential to detect CTCCs via label-free BSFC.

Fundus autofluorescence patterns in primary intraocular lymphoma

PURPOSE

To evaluate fundus autofluorescence (FAF) patterns in patients with primary intraocular (vitreoretinal) lymphoma.

METHODS

Records of all patients with primary intraocular lymphoma who underwent FAF imaging at the National Eye Institute were reviewed. Fundus autofluorescence patterns were evaluated with respect to clinical disease status and the findings on fluorescein angiography and spectral-domain optical coherence tomography.

RESULTS

There were 18 eyes (10 patients) with primary intraocular lymphoma that underwent FAF imaging. Abnormal autofluorescence in the form of granular hyperautofluorescence and hypoautofluorescence was seen in 11 eyes (61%), and blockage by mass lesion was seen in 2 eyes (11%). All eyes with granular pattern on FAF had active primary intraocular lymphoma at the time of imaging, but there were 5 eyes with unremarkable FAF, which were found to have active lymphoma. The most common pattern on fluorescein angiography was hypofluorescent round spots with a "leopard spot" appearance (43%). These hypofluorescent spots on fluorescein angiography correlated with hyperautofluorescent spots on FAF in 5 eyes (36%) (inversion of FAF). Nodular hyperreflective spots at the level of retinal pigment epithelium on optical coherence tomography were noted in 43% of eyes. The hyperautofluorescent spots on FAF correlated with nodular hyperreflective spots on optical coherence tomography in 6 eyes (43%).

CONCLUSION

Granularity on FAF was associated with active lymphoma in majority of the cases. An inversion of FAF (hyperautofluorescent spots on FAF corresponding to hypofluorescent spots on fluorescein angiography) was observed in less than half of the eyes.

Affinity of the alpha4-beta1 integrin-targeting peptide LLP2A to canine lymphoma

Lymphoma is an important disease in dogs and people, with similar biological characteristics. We tested the binding affinity of a peptidomimetic LLP2A, previously shown to bind the alpha4-beta1 integrin on human lymphoma cell lines, to lymphocytes of dogs with spontaneously occurring lymphoma. Fine needle aspirates of lymph nodes from 32 dogs with B-cell lymphoma and 7 dogs with T-cell lymphoma were evaluated using flow cytometry. For B cells, the lowest MFI levels were in unlabeled, non-neoplastic lymphocytes. The highest median fluorescent intensity (MFI) levels occurred in LLP2A-labeled lymphoma cells from dogs that had not received chemotherapy followed by labeled lymphoma cells from dogs that had received chemotherapy. The fluorescence profile of the T-cell samples was similar although many of the differences were not statistically significant, likely due to low sample number. Specifically, LLP2A-labeled T-cell lymphoma cells had a significantly higher MFI compared to unlabeled non-neoplastic lymphocytes. LLP2A affinity was not significantly different in unlabeled and labeled T-cell lymphoma cells, and labeled non-neoplastic lymphocytes. For both B and T cells, labeling with LLP2A tended to increase MFI in both normal and lymphoma cells. Lymphoma cells had higher mean MFI levels than non-neoplastic lymphocytes, and chemotherapy acted to decrease MFI. In summary, these data demonstrate that LLP2A has affinity to canine lymphoma cells and indicates expression of the alpha4-beta1 integrin on these cells. In fact, LLP2A preferentially binds neoplastic B-cells, suggesting that this small molecule may be of use in cross-species clinical trials of targeted therapeutics.

Tumor microenvironment is multifaceted

Cancer initiation, progression, and invasion occur in a complex and dynamic microenvironment which depends on the hosts and sites where tumors develop. Tumors arising in mucosal tissues may progress in an inflammatory context linked to local viral and/or bacterial infections. At the opposite, tumors developing in immunoprivileged sites are protected from microorganisms and grow in an immunosuppressive environment. In the present review, we summarize and present our recent data on the influence of infectious context and immune cell infiltration organization in human Non-Small Cell Lung Cancers (NSCLC) progression. We show that stimulation of tumor cells by TLR for viral ssRNA, such as TLR7/8, or bacteria, such as TLR4, promotes cell survival and induces chemoresistance. On the opposite, stimulation by TLR3, receptor for double-stranded viral RNA, decreases tumor cell viability and induces chemosensitivity in some lung tumor cell lines. Since fresh lung tumor cells exhibit a gene expression profile characteristic of TLR-stimulated lung tumor cell lines, we suspect that viral and bacterial influence may not only act on the host immune system but also directly on tumor growth and sensitivity to chemotherapy. The stroma of NSCLC contains tertiary lymphoid structures (or Tumor-induced Bronchus-Associated Lymphoid Tissues (Ti-BALT)) with mature DC, follicular DC, and T and B cells. Two subsets of immature DC, Langerhans cells (LC) and interstitial DC (intDC), were detected in the tumor nests and the stroma, respectively. Here, we show that the densities of the three DC subsets, mature DC, LC, and intDC, are highly predictive of disease-specific survival in a series of 74 early-stage NSCLC patients. We hypothesize that the mature DC may derive from local activation and migration of the immature DC--and especially LC which contact the tumor cells--to the tertiary lymphoid structures, after sampling and processing of the tumor antigens. In view of the prominent role of DC in the immune response, we suggest that the microenvironment of early-stage NSCLC may allow the in situ activation of the adaptive response. Finally, we find that the eyes or brain of mice with growing B cell lymphoma are infiltrated with T cells and that the cytokines produced ex vivo by the tumoral tissues have an impaired Th1 cytokine profile. Our work illustrates that the host and external tumor microenvironments are multifaceted and strongly influence tumor progression and anti-tumor immune responses.

Fundus autofluorescence patterns in eyes with primary intraocular lymphoma

PURPOSE

To evaluate the fundus autofluorescence (FAF) patterns in the eyes with primary intraocular lymphomas (PIOLs).

METHODS

A review of the medical charts of four consecutive patients (five eyes) with PIOL who had been studied by FAF. A fundus camera was used to obtain the FAF images. Optical coherence tomography was also performed.

RESULTS

The ophthalmoscopically observed brown clumps on the surface of greasy yellowish masses beneath the retinal pigmented epithelium had a bright hyperfluorescence appearance by FAF. This FAF hyperfluorescence was completely reversed to hypofluorescence in the fluorescein angiograms. The diffuse infiltration of the cells making up the PIOL above the retinal pigmented epithelium was ophthalmoscopically observed as a retinal whitening and was hypofluorescent by FAF. These areas of hypofluorescence were also reversed to areas of hyperfluorescence in the fluorescein angiogram. Fundus autofluorescence clearly delineated the retinal pigmented epithelium atrophy, which developed after the spontaneous resolution of the PIOL as a hypoautofluorescent area.

CONCLUSION

Because FAF can reveal various findings of PIOLs, it can be used to differentiate the patients with PIOL from those with ocular inflammatory diseases. Although further studies are required to determine whether these findings are characteristic to PIOL, this noninvasive method can then lead to earlier diagnosis and treatment.

The future of primary intraocular lymphoma (retinal lymphoma)

Basic science and clinical investigations in cancer research have contributed to our understanding of the genetic causes of various neoplasms and discovery of novel therapeutic interventions to fight malignancies such as lymphoma. During this exciting time, we have witnessed the advent of new technologies to further characterize primary intraocular lymphoma (PIOL), or retinal lymphoma, which is selected as the first "Disease of the Year" by Ocular Immunology and Inflammation. Different comprehensive aspects of PIOL, including epidemiology, clinical manifestations, diagnosis, pathophysiology, therapy, and animal models are discussed. The future of PIOL holds an opportunity to really understand the unique cytologic, histopathologic, physiological and immunologic features, as well as the genotypic traits (gene expression, interaction, polymorphism, epigenetics, etc.) and epidemiology. This information will empower us to truly make a difference in patients' managements with this devastating disease. While most of this technology already exists, much work still needs to be done to make translational therapy a reality for PIOL patients in the future.