Quantifying spatial position in a branched structure in immunostained mouse tissue sections

We have developed a protocol to quantify the position of a cell in a branched structure based on two-dimensional microscopy images of tissue sections. Biological branched structures include organs such as the lungs, kidneys, and pancreas. In these organs, cell fate has been correlated with position, based on a qualitative estimate. However, a quantitative means of evaluating the cell position has been lacking. With this protocol, the correlation between cell fate and cell position was measured in mouse embryonic pancreas.

For complete details on the use and execution of this protocol, please refer to Nyeng et al. (2019).

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A metric to quantify the position of a cell in a branched tissue structure

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Low score/high score indicates proximity to the center/periphery, respectively

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Score enables quantitative correlative studies of cell fate and cell position

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Comprehensive pipeline from tissue processing instructions to image analysis code

Cooperation between melanoma cell states promotes metastasis through heterotypic cluster formation

Melanomas can have multiple coexisting cell states, including proliferative (PRO) versus invasive (INV) subpopulations that represent a "go or grow" trade-off; however, how these populations interact is poorly understood. Using a combination of zebrafish modeling and analysis of patient samples, we show that INV and PRO cells form spatially structured heterotypic clusters and cooperate in the seeding of metastasis, maintaining cell state heterogeneity. INV cells adhere tightly to each other and form clusters with a rim of PRO cells. Intravital imaging demonstrated cooperation in which INV cells facilitate dissemination of less metastatic PRO cells. We identified the TFAP2 neural crest transcription factor as a master regulator of clustering and PRO/INV states. Isolation of clusters from patients with metastatic melanoma revealed a subset with heterotypic PRO-INV clusters. Our data suggest a framework for the co-existence of these two divergent cell populations, in which heterotypic clusters promote metastasis via cell-cell cooperation.

Abstract 1107: Cell state diversity promotes metastasis through heterotypic cluster formation in melanoma

Metastasis is the primary cause of cancer death, yet we know little about what determines its timing and aggressiveness. In melanoma, transcriptional profiling has revealed multiple co-existing cell states, including proliferative (PRO) versus invasive (INV) subpopulations that have been posited to represent a “go or grow” tradeoff in the etiology of metastasis. Although both of these populations are present in primary tumors and metastases, little is known about how they physically interact with each other in tumor dissemination. We use a combination of melanoma modeling in zebrafish and human validation to demonstrate that these subpopulations form spatially structured heterotypic clusters that cooperate in the seeding of metastasis. We unexpectedly found that INV cells were tightly adherent to each other and formed large tumor cell clusters. Mixing of PRO and INV cells generated heterotypic clusters, composed of a dense central core of INV cells surrounded by a rim of PRO cells. Using intravital imaging, we identified metastatic cooperation between these two subpopulations, in which the INV cells facilitated the earlier spread of the less metastatic PRO cells via collective extravasation. Mechanistically, we identified the TFAP2 family of neural crest transcription factors to be a master regulator of both clustering and the PRO/INV states. Knockout of TFAP2 from melanoma cells reduced proliferation but increased clustering and metastasis. TFAP2 loss resulted in increased expression of cell adhesion molecules, providing a mechanistic basis for cluster formation. Our data suggest a coherent framework for the co-existence of these two divergent cell populations in melanoma, in which differing cell states form heterotypic clusters that promote collective metastasis via cell-cell cooperation.

Citation Format: Nathaniel R. Campbell, Maomao Zhang, Maayan Baron, Silja Heilmann, Maxime Deforet, Lorenza Ferretti, Ting-Hsiang Huang, Mitchell P. Levesque, Itai Yanai, Joao B. Xavier, Richard M. White. Cell state diversity promotes metastasis through heterotypic cluster formation in melanoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1107.

p120ctn-Mediated Organ Patterning Precedes and Determines Pancreatic Progenitor Fate

The mechanism of how organ shape emerges and specifies cell fate is not understood. Pancreatic duct and endocrine lineages arise in a spatially distinct domain from the acinar lineage. Whether these lineages are pre-determined or settle once these niches have been established remains unknown. Here, we reconcile these two apparently opposing models, demonstrating that pancreatic progenitors re-localize to establish the niche that will determine their ultimate fate. We identify a p120ctn-regulated mechanism for coordination of organ architecture and cellular fate mediated by differential E-cadherin based cell sorting. Reduced p120ctn expression is necessary and sufficient to re-localize a subset of progenitors to the peripheral tip domain, where they acquire an acinar fate. The same mechanism is used re-iteratively during endocrine specification, where it balances the choice between the alpha and beta cell fates. In conclusion, organ patterning is regulated by p120ctn-mediated cellular positioning, which precedes and determines pancreatic progenitor fate.

Microenvironment-derived factors driving metastatic plasticity in melanoma

Cellular plasticity is a state in which cancer cells exist along a reversible phenotypic spectrum, and underlies key traits such as drug resistance and metastasis. Melanoma plasticity is linked to phenotype switching, where the microenvironment induces switches between invasive/MITF^LO versus proliferative/MITF^HI states. Since MITF also induces pigmentation, we hypothesize that macrometastatic success should be favoured by microenvironments that induce a MITF^HI/differentiated/proliferative state. Zebrafish imaging demonstrates that after extravasation, melanoma cells become pigmented and enact a gene expression program of melanocyte differentiation. We screened for microenvironmental factors leading to phenotype switching, and find that EDN3 induces a state that is both proliferative and differentiated. CRISPR-mediated inactivation of EDN3, or its synthetic enzyme ECE2, from the microenvironment abrogates phenotype switching and increases animal survival. These results demonstrate that after metastatic dissemination, the microenvironment provides signals to promote phenotype switching and provide proof that targeting tumour cell plasticity is a viable therapeutic opportunity.

Phenotype switching is a form of plasticity that allows melanoma cancer cells that leave the primary tumour to invade secondary sites, to switch from an invasive to a proliferative state. Here the authors identify EDN3, and its synthetic enzyme ECE2, as a regulator of melanoma plasticity in the microenvironment.

A Quantitative System for Studying Metastasis Using Transparent Zebrafish

Metastasis is the defining feature of advanced malignancy, yet remains challenging to study in laboratory environments. Here, we describe a high-throughput zebrafish system for comprehensive, in vivo assessment of metastatic biology. First, we generated several stable cell lines from melanomas of transgenic mitfa-BRAF(V600E);p53(-/-) fish. We then transplanted the melanoma cells into the transparent casper strain to enable highly quantitative measurement of the metastatic process at single-cell resolution. Using computational image analysis of the resulting metastases, we generated a metastasis score, μ, that can be applied to quantitative comparison of metastatic capacity between experimental conditions. Furthermore, image analysis also provided estimates of the frequency of metastasis-initiating cells (∼1/120,000 cells). Finally, we determined that the degree of pigmentation is a key feature defining cells with metastatic capability. The small size and rapid generation of progeny combined with superior imaging tools make zebrafish ideal for unbiased high-throughput investigations of cell-intrinsic or microenvironmental modifiers of metastasis. The approaches described here are readily applicable to other tumor types and thus serve to complement studies also employing murine and human cell culture systems.

Why do bacteria regulate public goods by quorum sensing?-How the shapes of cost and benefit functions determine the form of optimal regulation

Many bacteria secrete compounds which act as public goods. Such compounds are often under quorum sensing (QS) regulation, yet it is not understood exactly when bacteria may gain from having a public good under QS regulation. Here, we show that the optimal public good production rate per cell as a function of population size (the optimal production curve, OPC) depends crucially on the cost and benefit functions of the public good and that the OPC will fall into one of two categories: Either it is continuous or it jumps from zero discontinuously at a critical population size. If, e.g., the public good has accelerating returns and linear cost, then the OPC is discontinuous and the best strategy thus to ramp up production sharply at a precise population size. By using the example of public goods with accelerating and diminishing returns (and linear cost) we are able to determine how the two different categories of OPSs can best be matched by production regulated through a QS signal feeding back on its own production. We find that the optimal QS parameters are different for the two categories and specifically that public goods which provide accelerating returns, call for stronger positive signal feedback.

Evidence for a polygenic contribution to androgenetic alopecia

BACKGROUND

Male pattern baldness (androgenetic alopecia, AGA) is a highly heritable trait and the most common form of hair loss in humans. Eight genome-wide significant risk loci for AGA have been identified.

OBJECTIVES

To determine whether a polygenic component contributes to the genetic risk for AGA.

METHODS

This study used a German case-control sample for AGA, which comprised 581 severely affected patients and 617 controls, to determine the contribution of polygenic variance to AGA risk. The sample was divided evenly into discovery and test samples. An additive polygenic risk score was calculated from risk alleles with increasingly liberal P-values in the discovery dataset, which was then used to test for the enrichment of AGA risk score alleles in the independent test samples.

RESULTS

The polygenic score analysis provided significant evidence for a polygenic contribution to AGA where the amount of variance explained was 1·4-4·5%.

CONCLUSION

This study provides evidence for the specific contribution of a polygenic component to the overall heritable risk for AGA. To some degree, the polygenic architecture of AGA might reflect the complexity of the biological pathways involved. Further analyses and strategies that complement conventional genome-wide association studies are needed to identify these factors. These may include pathway-based analyses, the analysis of functional candidate genes and tests for epistatic effects with known loci.

Follow-up of loci from the International Genomics of Alzheimer's Disease Project identifies TRIP4 as a novel susceptibility gene

To follow-up loci discovered by the International Genomics of Alzheimer's Disease Project, we attempted independent replication of 19 single nucleotide polymorphisms (SNPs) in a large Spanish sample (Fundació ACE data set; 1808 patients and 2564 controls). Our results corroborate association with four SNPs located in the genes INPP5D, MEF2C, ZCWPW1 and FERMT2, respectively. Of these, ZCWPW1 was the only SNP to withstand correction for multiple testing (P=0.000655). Furthermore, we identify TRIP4 (rs74615166) as a novel genome-wide significant locus for Alzheimer's disease risk (odds ratio=1.31; confidence interval 95% (1.19-1.44); P=9.74 × 10(-)(9)).

Microdeletions including FMR1 in three female patients with intellectual disability - further delineation of the phenotype and expression studies

Fragile X syndrome (FXS) is one of the most common causes of intellectual disability/developmental delay (ID/DD), especially in males. It is caused most often by CGG trinucleotide repeat expansions, and less frequently by point mutations and partial or full deletions of the FMR1 gene. The wide clinical spectrum of affected females partly depends on their X-inactivation status. Only few female ID/DD patients with microdeletions including FMR1 have been reported. We describe 3 female patients with 3.5-, 4.2- and 9.2-Mb de novo microdeletions in Xq27.3-q28 containing FMR1. X-inactivation was random in all patients, yet they presented with ID/DD as well as speech delay, macrocephaly and other features attributable to FXS. No signs of autism were present. Here, we further delineate the clinical spectrum of female patients with microdeletions. FMR1 expression studies gave no evidence for an absolute threshold below which signs of FXS present. Since FMR1 expression is known to be highly variable between unrelated females, and since FMR1 mRNA levels have been suggested to be more similar among family members, we further explored the possibility of an intrafamilial effect. Interestingly, FMR1 mRNA levels in all 3 patients were significantly lower than in their respective mothers, which was shown to be specific for patients with microdeletions containing FMR1.

Exploiting social evolution in biofilms

Bacteria are highly social organisms that communicate via signaling molecules, move collectively over surfaces and make biofilm communities. Nonetheless, our main line of defense against pathogenic bacteria consists of antibiotics-drugs that target individual-level traits of bacterial cells and thus, regrettably, select for resistance against their own action. A possible solution lies in targeting the mechanisms by which bacteria interact with each other within biofilms. The emerging field of microbial social evolution combines molecular microbiology with evolutionary theory to dissect the molecular mechanisms and the evolutionary pressures underpinning bacterial sociality. This exciting new research can ultimately lead to new therapies against biofilm infections that exploit evolutionary cheating or the trade-off between biofilm formation and dispersal.

Acyl-homoserine lactone-dependent eavesdropping promotes competition in a laboratory co-culture model

Many Proteobacteria use acyl-homoserine lactone (AHL)-mediated quorum sensing to activate the production of antibiotics at high cell density. Extracellular factors like antibiotics can be considered public goods shared by individuals within a group. Quorum-sensing control of antibiotic production may be important for protecting a niche or competing for limited resources in mixed bacterial communities. To begin to investigate the role of quorum sensing in interspecies competition, we developed a dual-species co-culture model using the soil saprophytes Burkholderia thailandensis (Bt) and Chromobacterium violaceum (Cv). These bacteria require quorum sensing to activate the production of antimicrobial factors that inhibit growth of the other species. We demonstrate that quorum-sensing-dependent antimicrobials can provide a competitive advantage to either Bt or Cv by inhibiting growth of the other species in co-culture. Although the quorum-sensing signals differ for each species, we show that the promiscuous signal receptor encoded by Cv can sense signals produced by Bt, and that this ability to eavesdrop on Bt can provide Cv an advantage in certain situations. We use an in silico approach to investigate the effect of eavesdropping in competition, and show conditions where early activation of antibiotic production resulting from eavesdropping can promote competitiveness. Our work supports the idea that quorum sensing is important for interspecies competition and that promiscuous signal receptors allow eavesdropping on competitors in mixed microbial habitats.

Susceptibility variants on chromosome 7p21.1 suggest HDAC9 as a new candidate gene for male-pattern baldness

BACKGROUND

Male-pattern baldness (androgenetic alopecia, AGA) is the most common form of hair loss among humans. Research has shown that it is caused by genetic factors. Numerous studies have unequivocally identified two major genetic risk loci for AGA: the X-chromosomal AR/EDA2R locus, and the PAX1/FOXA2 locus on chromosome 20.

OBJECTIVES

To identify further candidate genes for AGA, and thus gain further insights into this phenotype.

METHODS

A German sample of 581 severely affected cases and 617 controls was used to perform a genome-wide association study. The identified associated locus was further analysed by fine-mapping, and then independently replicated in an Australian sample. Expression and pathway analyses were performed to characterize the susceptibility gene identified.

RESULTS

The most significant association signal was obtained for rs756853 (P = 1·64 × 10(-7) ), which is located intronically in the histone deacetylase 9 (HDAC9) gene. Fine-mapping and a family-based analysis revealed that rs756853 and the 6-kb distal rs2249817 were the most highly associated single nucleotide polymorphisms. The association finding was replicated in an independent Australian sample, when the analysis was restricted to severely affected cases and unaffected controls (P = 0·026). Analysis of rs2249817 in a combined sample of severely affected German and Australian cases and unaffected controls revealed a strong association signal (P = 9·09 × 10(-8) ). Tissue expression studies demonstrated HDAC9 expression in various tissues, including tissues of relevance to AGA. No strong genotypic effects were observed in genotype-specific expression or splice studies. Pathway analyses supported the hypothesis that HDAC9 plays a functional role in AGA via interaction with the AR gene.

CONCLUSIONS

The present study suggests that HDAC9 is the third AGA susceptibility gene.

[Effects of systemic or topical administration of corticosteroids and vitamin B in patients with olfactory loss]

BACKGROUND

Aim of the present, unblinded, multicentric, open trial was to compare effects of 3 treatments in patients with olfactory dysfunction.

METHODS

Treatments included administration of systemic corticosteroids (oral prednisolone), local corticosteroids (mometasone nasal spray), and systemic vitamin B, respectively. A total of 192 patients participated (95 women, 97 men; mean age 56 years). Duration of the smell loss ranged from 1 to 288 months (average 45 months). Olfactory dysfunction was due to infections of the upper respiratory tract (n = 72), sinunasal disease (n = 19), and posttraumatic olfactory loss (n = 10); the largest portion was classified as idiopathic (n = 85); other causes were rare (n = 6).

RESULTS

Following systemic administration of corticosteroids improvement of olfactory function was observed (p < 0.001). Similarly, improvement of the sense of smell was found 2 (p = 0.03) and 6 months (p = 0.001) after local administration of mometasone, respectively. In contrast, after administration of vitamin B no significant change of olfactory function was seen after 2 months, while improvement was present after 6 months (p = 0.001). Duration of olfactory dysfunction had no effect on changes of smell function.

CONCLUSIONS

These results indicate that improvement of olfactory function is found in olfactory dysfunction of different causes. Adequately controlled, blinded studies are needed to further explore potential effects of the various treatments.

Clinical presentation of qualitative olfactory dysfunction

Many patients with olfactory dysfunction not only experience quantitative reduction of olfactory function, but also suffer from distorted olfactory sensations. This qualitative dysfunction is referred to as parosmia (also called "troposmia") or phantosmia, with the major difference that distorted olfactory sensations are experienced in the presence or absence of an odor, respectively. Our clinical observations corroborate the literature in terms of a general underestimation of the incidence of olfactory distortions. Based on selected cases we try to show that olfactory distortions exhibit a large variance in their clinical appearance. Further, emphasis is placed on the fact that only a detailed and directed history of the patient can provide cues to the correct diagnosis.

Immunohistochemical distribution of galectin-1, galectin-3, and olfactory marker protein in human olfactory epithelium

The expression pattern of galectin-1 and galectin-3 in the human olfactory epithelium was investigated in relation to olfactory marker protein (OMP) using confocal laser immunofluorescence in human specimens and postmortem biopsies. OMP expression was found in olfactory receptor neurons (ORNs) in the olfactory mucosa and in fibers of the olfactory nerve crossing the submucous connective tissue. Galectin-1 was expressed in both the connective tissue of the nasal cavity and in the basal layer of the olfactory epithelium. In contrast, galectin-3 expression was limited to cells of the upper one-third of the olfactory epithelium. Expression of galectin-3 occurred in a subset of OMP-positive cells. However, between areas of galectin-1 and galectin-3 expression in the lower and upper portion of the epithelium, OMP-positive ORNs did not stain for both galectins. Considering the potential role of galectin-1 and galectin-3 in cell differentiation and maturation, the differential localization of galectins in the olfactory epithelium appears to be consistent with a significant role of these molecules in the physiological turnover of ORNs.

[Gustatory olfactory function test with the Güttich technique: an evaluation of the clinical value]

BACKGROUND

Testing of retronasal olfactory sensitivity is routinely performed in many ENT-departments in German speaking countries. One of the most popular tests relates to an anecdotal report by Güttich [1]. In this test, liquids are placed on the patient's tongue; the patient is then asked to describe the aroma. Assuming that anosmic patients should not use other descriptors than "sweet," "sour," "salty," and "bitter", this test design is frequently applied in disability compensation settings. Surprisingly though, so far there are no studies regarding the sensitivity or specificity of this test in terms of the differentiation between hyposmic and anosmic patients.

METHODS

The present investigation was performed in 50 anosmics, 42 hyposmics, and 13 normosmics. The diagnosis "hyposmia" or "anosmia" was based on 1. the patients' history, 2. psychophysical tests using an established test of olfactory function, the "Sniffin' Sticks," and 3. the recording of olfactory evoked potentials.

RESULTS

We obtained the following major results: 1. In comparison to hyposmis and normosmics, anosmic patients had greater difficulty identifying the aromas. However, correct identification was not always possible for normosmics. 2. Regarding the differentiation between anosmic and hyposmic patients, the test's sensitivity was 86% with a specificity of 62%. This clearly limits routine clinical application of this test.

CONCLUSIONS

Retronasal testing appears to be an elegant and simple means in order to screen olfactory function. However, the presently investigated approach is limited with regard to the discrimination between anosmic and hyposmic patients.

The use of antibodies for characterization and quantification of a recombinant protein

In this study, we characterized proteinase A secreted by recombinant Saccharomyces cerevisiae bearing a multicopy plasmid containing the encoding gene (PEP4). Polyclonal and monoclonal antibodies were raised to study the product heterogeneity. Characterization of proteinase A was performed by immunoelectrophoresis and immunoblotting techniques. None of the monoclonal antibodies raised against proteinase A was found to react with the glycosyl side chains; thus cross-reaction with other glycosylated proteins (e.g. carboxypeptidase Y) was very low. This study allowed us to develop an ELISA method for the quantification of proteinase A in culture supernatants as well as the evaluation of monoclonal antibodies for their use in immunoaffinity chromatography.

[Bone changes in long-term therapy with etretinate (Tigason)]

We report on a 10-year-old girl with ichthyosis vulgaris, suffering from pains in her left arm and wrist after 1 1/2 years' treatment with etretinate (Tigason) The activity of the alkaline phosphatase was increased. Scintigraphy with technetium showed increased accumulation of activity as well as beginning transformation processes of the left ulna, which recovered after the reduction of the maintenance dose and are no longer detectable after a total of 3 1/2 years' treatment. The potential bone toxicity must be taken into consideration in long-term treatment with retinoids. Its manifestation should be prevented by thorough follow-up.

[Psoriasis therapy with the aromatic retinoid Ro 10-9359 (Tigason)]

At three University Departments of Dermatology (Berlin, Leipzig, Erfurt) of the GRD, 63 psoriatics (46 men, 17 women) were treated with aromatic retinoid Ro 10-9359 (Tigason) up to a maximum of 84 weeks. In 34 of these cases, photochemotherapy was additionally applied. This combination resulted in a more rapid healing than Tigason alone. The average initial dose amounted to 1 mg per kg body weight. Only in cases of psoriatic erythroderma, the treatment started with a daily rate of 25 mg Tigason. The maintenance dose came to 50 to 25 mg daily. On account of deterioration of the cutaneous condition and/or heavy itching, the treatment had to be discontinued in 4 cases. Side effects as cheilitis, rhagades, loss of hair, and onycholysis disappeared after reduction of the dose. Our study confirmed the good therapeutical effect of Tigason with the various forms of psoriasis.

[Echographic early diagnosis of chronic alcoholic pancreatitis? (author's transl)]

The normal size of the pancreas should be checked and classified in a large collection of abstinent people of various ages. We are of the opinion that abstinent persons have a pancreas less than 1.5 cm thick and that great deviations are of exogenous origin. Alcohol presumably leads to edema of the pancreas. If alcohol is abused increasingly and/or persistently, a low-echo enlargement of the pancreas of more than 2.5 cm appears. A clinically detectable pancreatic insufficiency only occurs when the lymph drainage in the acini of the pancreas is damaged through decompensation and a reduction of secretion results. This process seems to have a course of 6-10 years and to run parallel with the consumption of alcohol.

[Echography, laparoscopy and histology in diffuse liver diseases (author's transl)]

The incidence of error of echography (21.0%), laparoscopy (15.0%) and histology (17.4% was investigated in 504 cases of diffuse liver disease. In the assessment of fatty liver, acute fatty liver, fatty cirrhosis and fibroses the accuracy of echography was comparable to that of laparoscopy and histology. A prerequisite for this is that the assessment of the spleen is given particular attention during the diagnosis of diffuse liver diseases. The assessment of diffuse liver diseases demands a high degree of training of the echography diagnostician.

[Impetigo herpetiformis and PUVA-treatment (author's transl)]

Report on a 20 years old pregnant woman, who fulfilled the criteria of the impetigo herpetiformis as well as later those of the pustular psoriasis Zumbusch in her clinical course. The impetigo herpetiformis is interpreted as a variant of the pustular psoriasis occurring during the pregnancy with lowered calcium-level, which increases the endogeneous eruption pressure. After negative attempts of treatment with Prednisolon, antibiotics, and later with Methotrexat an excellent therapeutic effect could be achieved by oral PUVA-treatment.

[The effect of caerulein on intraluminal pressures of the common bile duct and duodenum in man (author's transl)]

Caerulein is a dekapeptide related to gastrin and cholecystokinin with profound effects on gastrointestinal motility. In the present study we examined the effect of intravenously administered caerulein (0.1 microgram/kg body weight) on the intraluminal pressure of common bile duct and duodenum in 12 patients. The pressure recordings were obtained by endoscopic perfusion manometry. The tip of the perfused catheter was positioned under radiological control and the measurements were carried out under standardized conditions. Following the injection of caerulein there was a rise in pressure in the common bile duct and the mid portion of the duodenum. The pressure increase in the common duct appears to be predominantly due to contraction of the gallbladder as it is considerably less pronounced in patients with cholecystectomy. The problems inherent to endoscopic pressure recordings under pharmacological stimulation are discussed.