Widespread monoclonal IgE antibody convergence to an immunodominant, proanaphylactic Ara h 2 epitope in peanut allergy

BACKGROUND

Despite their central role in peanut allergy, human monoclonal IgE antibodies have eluded characterization.

OBJECTIVE

We sought to define the sequences, affinities, clonality, and functional properties of human monoclonal IgE antibodies in peanut allergy.

METHODS

We applied our single-cell RNA sequencing-based SEQ SIFTER discovery platform to samples from allergic individuals who varied by age, sex, ethnicity, and geographic location in order to understand commonalities in the human IgE response to peanut allergens. Select antibodies were then recombinantly expressed and characterized for their allergen and epitope specificity, affinity, and functional properties.

RESULTS

We found striking convergent evolution of IgE monoclonal antibodies (mAbs) from several clonal families comprising both memory B cells and plasmablasts. These antibodies bound with subnanomolar affinity to the immunodominant peanut allergen Ara h 2, specifically a linear, repetitive motif. Further characterization of these mAbs revealed their ability to single-handedly cause affinity-dependent degranulation of human mast cells and systemic anaphylaxis on peanut allergen challenge in humanized mice. Finally, we demonstrated that these mAbs, reengineered as IgGs, inhibit significant, but variable, amounts of Ara h 2- and peanut-mediated degranulation of mast cells sensitized with allergic plasma.

CONCLUSIONS

Convergent evolution of IgE mAbs in peanut allergy is a common phenomenon that can reveal immunodominant epitopes on major allergenic proteins. Understanding the functional properties of these molecules is key to developing therapeutics, such as competitive IgG inhibitors, that are able to stoichiometrically outcompete endogenous IgE for allergen and thereby prevent allergic cascade in cases of accidental allergen exposure.

Phenotypic and Histological Distribution Analysis Identify Mast Cell Heterogeneity in Non-Small Cell Lung Cancer

Simple Summary

During the fight against tumor, some cells of the immune system such as cytotoxic lymphocytes eliminate tumoral cells while others such as tumor-associated macrophages favor tumor development. Mast cells (MCs) are multifaceted immune cells whose role in cancer is still poorly understood. Moreover, MCs are poorly characterized in the context of cancer and their presence in the tumor microenvironment has been reported to be either associated with good or bad prognosis. In this pilot study we characterized tumor-associated MCs (TAMCs) in lung cancer. We showed that TAMCs exhibited a typical phenotype and can be classified in two subsets according to alphaE integrin (CD103) expression. CD103⁺ TAMCs appeared more mature, more prone to interact with CD4⁺ T cells, and located closer to cancer cells than their CD103⁻ counterpart. This study revealed that a high frequency of total TAMC correlated with better overall survival and progression free survival in patients and underlined MC heterogeneity in cancer.

Abstract

Mast cells (MCs) are multifaceted innate immune cells often present in the tumor microenvironment (TME). However, MCs have been only barely characterized in studies focusing on global immune infiltrate phenotyping. Consequently, their role in cancer is still poorly understood. Furthermore, their prognosis value is confusing since MCs have been associated with good and bad (or both) prognosis depending on the cancer type. In this pilot study performed on a surgical cohort of 48 patients with Non-Small Cell Lung Cancer (NSCLC), we characterized MC population within the TME and in matching non-lesional lung areas, by multicolor flow cytometry and confocal microscopy. Our results showed that tumor-associated MCs (TAMCs) harbor a distinct phenotype as compared with MCs present in non-lesional counterpart of the lung. Moreover, we found two TAMCs subsets based on the expression of CD103 (also named alphaE integrin). CD103⁺ TAMCs appeared more mature, more prone to interact with CD4⁺ T cells, and located closer to cancer cells than their CD103⁻ counterpart. In spite of these characteristics, we did not observe a prognosis advantage of a high frequency of CD103⁺ TAMCs, while a high frequency of total TAMC correlated with better overall survival and progression free survival. Together, this study reveals that TAMCs constitute a heterogeneous population and indicates that MC subsets should be considered for patients’ stratification and management in future research.

IL-17+ Mast Cell/T Helper Cell Axis in the Early Stages of Acne

Acne is a multifactorial disease driven by physiological changes occurring during puberty in the pilosebaceous unit (PSU) that leads to sebum overproduction and a dysbiosis involving notably Cutibacterium acnes. These changes in the PSU microenvironment lead to a shift from a homeostatic to an inflammatory state. Indeed, immunohistochemical analyses have revealed that inflammation and lymphocyte infiltration can be detected even in the infraclinical acneic stages, highlighting the importance of the early stages of the disease. In this study, we utilized a robust multi-pronged approach that included flow cytometry, confocal microscopy, and bioinformatics to comprehensively characterize the evolution of the infiltrating and resident immune cell populations in acneic lesions, beginning in the early stages of their development. Using a discovery cohort of 15 patients, we demonstrated that the composition of immune cell infiltrate is highly dynamic in nature, with the relative abundance of different cell types changing significantly as a function of clinical lesion stage. Within the stages examined, we identified a large population of CD69⁺ CD4⁺ T cells, several populations of activated antigen presenting cells, and activated mast cells producing IL-17. IL-17⁺ mast cells were preferentially located in CD4⁺ T cell rich areas and we showed that activated CD4⁺ T cells license mast cells to produce IL-17. Our study reveals that mast cells are the main IL-17 producers in the early stage of acne, underlying the importance of targeting the IL-17⁺ mast cell/T helper cell axis in therapeutic approaches.

The inhibitory receptor CD94/NKG2A on CD8+ tumor-infiltrating lymphocytes in colorectal cancer: a promising new druggable immune checkpoint in the context of HLAE/β2m overexpression

We previously demonstrated that HLA-E/β2m overexpression by tumor cells in colorectal cancers is associated with an unfavorable prognosis. However, the expression of its specific receptor CD94/NKG2 by intraepithelial tumor-infiltrating lymphocytes, their exact phenotype and function, as well as the relation with the molecular status of colorectal cancer and prognosis remain unknown. Based on a retrospective cohort of 234 colorectal cancer patients, we assessed the expression of HLA-E, β2m, CD94, CD8, and NKp46 by immunohistochemistry on tissue microarray. The expression profile of HLA-E/β2m on tumor cells and the density of tumor-infiltrating lymphocytes were correlated to the clinicopathological and molecular features (Microsatellite status, BRAF and RAS mutations). Then, from the primary tumors of 27 prospective colorectal cancers, we characterized by multiparameter flow cytometry the nature (T and/or NK cells) and the co-expression of the inhibitory NKG2A or activating NKG2C chain of ex vivo isolated CD94+ tumor-infiltrating lymphocytes. Their biological function was determined using an in vitro redirected cytolytic activity assay. Our results showed that HLA-E/β2m was preferentially overexpressed in microsatellite instable tumors compared with microsatellite stable ones (45% vs. 19%, respectively, p = 0.0001), irrespective of the RAS or BRAF mutational status. However, HLA-E/β2m+ colorectal cancers were significantly enriched in CD94+ intraepithelial tumor-infiltrating lymphocytes in microsatellite instable as well as in microsatellite stable tumors. Those CD94+ tumor-infiltrating lymphocytes mostly corresponded to CD8+ αβ T cells, and  to a lesser extent to NK cells, and mainly co-expressed a functional inhibitory NKG2A chain. Finally, a high number of CD94+ intraepithelial tumor-infiltrating lymphocytes in close contact with tumor cells was independently associated with a worse overall survival. In conclusion, these findings strongly suggest that HLA-E/β2m-CD94/NKG2A represents a new druggable inhibitory immune checkpoint, preferentially expressed in microsatellite instable tumors, but also in a subgroup of microsatellite stable tumors, leading to a new opportunity in colorectal cancer immunotherapies.

Intraepithelial CD94+ tumor-infiltrating lymphocytes in a context of HLA-E overexpression as a new immune checkpoint to predict prognosis in colorectal carcinomas

e14592

Background: A better understanding of the immune-modulating interactions between tumor cells and immune cells underlying the balance between immune control and immune resistance in colorectal cancer (CRC) is crucial for the design of immunotherapies. We have previously demonstrated that overexpression of the human MHC class Ib molecule - HLA-E/β2 microglobulin - by tumor cells in CRC was associated with an unfavorable prognosis, suggesting its involvement in immune escape. However, the specific receptor of HLA-E/β2m - CD94/NKG2A, inhibitory or CD94/NKG2C, activating - expressed by tumor-infiltrating lymphocytes (TIL), as well as the influence of the microsatellite status in HLA-E/β2m overexpression, remain unknown. Methods: We investigated in the primary tumor of 245 CRC patients 1) the association of HLA-E/β2m overexpression and the density of CD94+ intraepithelial TIL (IEL-TIL) with the microsatellite status, 2) the nature of CD94+ TIL and the receptor expressed - CD94/NKG2A or CD94/NKG2C - and 3) the prognostic influence of CD94+ IEL-TIL. Results: HLA-E/β2m was preferentially overexpressed in MSI compared with MSS CRC (44,6 % vs 18,4 % respectively, p = 0.0001), and significantly associated with a high density of CD94+ IEL-TIL in MSI (0,9% in HLA-E/β2m+ vs 0,2% in HLA-E/β2m– CRC, p = 0,001), and in MSS CRC (0,38% vs 0,15%, p < 0,0001). These CD94+ TIL mostly corresponded to CD8+ αβ T cells preferentially expressing the inhibitory NKG2A chain. Finally, a high density of CD94+ IEL-TIL was independently associated with a worse OS (p = 0.03). Conclusions: These results strongly suggest that HLA-E/β2m - CD94/NKG2A interactions, preferentially up-regulated in MSI CRC, represent a promising inhibitory immune checkpoint. From a clinical point of view, this inhibitory immune checkpoint could be blocked by the new anti-NKG2A monoclonal antibody.

Comparison of MR-arthrography and CT-arthrography in hyaline cartilage-thickness measurement in radiographically normal cadaver hips with anatomy as gold standard

OBJECTIVE

To compare magnetic resonance (MR)-arthrography and multidetector-spiral-computed-tomography (MDSCT)-arthrography in cartilage-thickness measurement, in hips without cartilage loss, with coronal anatomic slices as gold standard.

METHOD

Institutional review board permission to study cadavers of individuals who willed their bodies to science was obtained. Two independent observers measured femoral and acetabular cartilage thicknesses of 12 radiographically normal hips (six women, five men; age range, 52-98 years; mean age, 76.5 years), on MDSCT-arthrographic and MR-arthrographic reformations, and on coronal anatomic slices, excluding regions of cartilage loss. Inter- and intraobserver reproducibilities were determined. Analysis of variance (ANOVA) was used to test differences between MR-arthrographic and MDSCT-arthrographic measurement errors compared to anatomy.

RESULTS

By MR-arthrography, cartilage was not measurable at approximately 50% of points on sagittal and transverse sections, compared to 0-6% of the points by MDSCT-arthrography. In the coronal plane, the difference between MDSCT-arthrographic and MR-arthrographic measurement errors was not significant (P=0.93).

CONCLUSION

In the coronal plane, MR-arthrography and MDSCT-arthrography were similarly accurate for measuring hip cartilage thickness.

Shear effects in nonhomogeneous turbulence

Motivated by recent experimental and numerical results, a simple unifying picture of intermittency in turbulent shear flows is suggested. Integral structure functions (ISF), taking into account explicitly the shear intensity, are introduced on phenomenological grounds. ISF can exhibit a universal scaling behavior, independent of the shear intensity. This picture is in satisfactory agreement with both experimental and numerical data. Possible extension to convective turbulence and implication on closure conditions for large-eddy simulation of nonhomogeneous flows are briefly discussed.

Tricyclic antidepressant-induced extrapyramidal side effects

Two cases of tricyclic antidepressant-related extrapyramidal side effects are reported and, the authors review the literature describing these effects. Despite clear case reports, these side effects are not well known. Given the wide prescription of tricyclic antidepressants (TCA) and the low number of case reports, the prevalence of these side effects is indeed low, but clinical implications exist. The extrapyramidal symptoms induced by TCA alone are acute or tardive dyskinesia, akathisia, myoclonus, rabbit syndrome and dystonia. These symptoms seem to be non age-related, but often dose-related, and were responders to antiparkinsonian agents or propranolol. The factors that predispose an individual to the development of these side effects are not completely understood. Some risk factors such as prior exposure to neuroleptics and/or lithium or estrogens could facilitate the development of these side effects. In some cases, they can disappear even though the same dose of TCA is continued, and they do not seem to be a drug class reaction. The susceptibility of each individual patient to the development of these disorders may be limited to only one or a few of these agents.

Effect of the interaction between transforming growth factor beta and erythropoietin on the proliferation of normal erythroid progenitors and leukemic UT-7 cells: action of transforming growth factor beta on the erythropoietin receptor

The actions of transforming growth factor beta (TGF beta) and erythropoietin (Epo) were studied using normal erythroid progenitors from fetal rat liver and spleen at 18, 19 and 20 days. rhTGF beta 1 inhibited the growth of late BFUe colonies significantly at each age and in both organs in methylcellulose cultures containing 2 U/ml rhEpo. There was no significant inhibition of CFUe proliferation, except for spleen CFUe at 18 days, suggesting different CFUe sensitivities to growth factors at a given fetal age, 18 days, in liver and spleen. The colorimetric MTT assay was used to examine the inhibition of the growth of human leukemic UT-7 cells by TGF beta 1. TGF beta 1 inhibited the proliferation of UT-7 cells in cultures without Epo at 24 h and in cultures with Epo at 24 and 72 h. The specific binding of [125I]Epo to UT-7 surface was decreased by TGF beta 1 without any change in non-specific binding. TGF beta 1 also inhibited the expression of Epo-receptors on UT-7 cells, without changing receptor affinity. The inhibition of hematopoietic progenitor cell growth by TGF beta could involve altering the cell surface expression of growth factor receptors.