Nuclear morphology is shaped by loop-extrusion programs.

It is well established that neutrophils adopt malleable polymorphonuclear shapes to migrate through narrow interstitial tissue spaces1-3. However, how polymorphonuclear structures are assembled remains unknown4. Here we show that in neutrophil progenitors, halting loop extrusion-a motor-powered process that generates DNA loops by pulling in chromatin5-leads to the assembly of polymorphonuclear genomes. Specifically, we found that in mononuclear neutrophil progenitors, acute depletion of the loop-extrusion loading factor nipped-B-like protein (NIPBL) induced the assembly of horseshoe, banded, ringed and hypersegmented nuclear structures and led to a reduction in nuclear volume, mirroring what is observed during the differentiation of neutrophils. Depletion of NIPBL also induced cell-cycle arrest, activated a neutrophil-specific gene program and conditioned a loss of interactions across topologically associating domains to generate a chromatin architecture that resembled that of differentiated neutrophils. Removing NIPBL resulted in enrichment for mega-loops and interchromosomal hubs that contain genes associated with neutrophil-specific enhancer repertoires and an inflammatory gene program. On the basis of these observations, we propose that in neutrophil progenitors, loop-extrusion programs produce lineage-specific chromatin architectures that permit the packing of chromosomes into geometrically confined lobular structures. Our data also provide a blueprint for the assembly of polymorphonuclear structures, and point to the possibility of engineering de novo nuclear shapes to facilitate the migration of effector cells in densely populated tumorigenic environments.

Human coronavirus OC43-elicited CD4+ T cells protect against SARS-CoV-2 in HLA transgenic mice.

SARS-CoV-2-reactive T cells are detected in some healthy unexposed individuals. Human studies indicate these T cells could be elicited by the common cold coronavirus OC43. To directly test this assumption and define the role of OC43-elicited T cells that are cross-reactive with SARS-CoV-2, we develop a model of sequential infections with OC43 followed by SARS-CoV-2 in HLA-B*0702 and HLA-DRB1*0101 Ifnar1-/- transgenic mice. We find that OC43 infection can elicit polyfunctional CD8+ and CD4+ effector T cells that cross-react with SARS-CoV-2 peptides. Furthermore, pre-exposure to OC43 reduces subsequent SARS-CoV-2 infection and disease in the lung for a short-term in HLA-DRB1*0101 Ifnar1-/- transgenic mice, and a longer-term in HLA-B*0702 Ifnar1-/- transgenic mice. Depletion of CD4+ T cells in HLA-DRB1*0101 Ifnar1-/- transgenic mice with prior OC43 exposure results in increased viral burden in the lung but no change in virus-induced lung damage following infection with SARS-CoV-2 (versus CD4+ T cell-sufficient mice), demonstrating that the OC43-elicited SARS-CoV-2 cross-reactive T cell-mediated cross-protection against SARS-CoV-2 is partially dependent on CD4+ T cells. These findings contribute to our understanding of the origin of pre-existing SARS-CoV-2-reactive T cells and their effects on SARS-CoV-2 clinical outcomes, and also carry implications for development of broadly protective betacoronavirus vaccines.

YAP-Driven Malignant Reprogramming of Epithelial Stem Cells at Single Cell Resolution.

Tumor initiation represents the first step in tumorigenesis during which normal progenitor cells undergo cell fate transition to cancer. Capturing this process as it occurs in vivo, however, remains elusive. Here we employ cell tracing approaches with spatiotemporally controlled oncogene activation and tumor suppressor inhibition to unveil the processes underlying oral epithelial progenitor cell reprogramming into cancer stem cells (CSCs) at single cell resolution. This revealed the rapid emergence of a distinct stem-like cell state, defined by aberrant proliferative, hypoxic, squamous differentiation, and partial epithelial to mesenchymal (pEMT) invasive gene programs. Interestingly, CSCs harbor limited cell autonomous invasive capacity, but instead recruit myeloid cells to remodel the basement membrane and ultimately initiate tumor invasion. CSC transcriptional programs are conserved in human carcinomas and associated with poor patient survival. These findings illuminate the process of cancer initiation at single cell resolution, thus identifying candidate targets for early cancer detection and prevention.

Direct reprogramming of oral epithelial progenitor cells to cancer stem cells at single cell resolution in vivo.

Tumor initiation represents the initial step in tumorigenesis during which normal progenitor cells undergo cell fate transition to cancer. Most studies investigating cancer-driving mechanisms in solid tumors rely on analyses of established malignant lesions, and thus cannot directly capture processes underlying the reprogramming of normal progenitor cells into cancer cells. Here, using spatiotemporally controlled oncogene expression in a genetically engineered system we demonstrate that concomitant YAP activation and HPV E6-E7 -mediated inhibition of tumor suppressive pathways is sufficient to rapidly reprogram oral epithelial progenitor cells (OEPCs) into cancer stem cells (CSCs). Single cell analyses of these nascent CSCs revealed hallmark transcriptional programs driving tumor initiation. Importantly, these CSC-enriched expression signatures distinguish normal tissue from malignant head and neck tumors and are associated with poor patient survival. Elucidating mechanisms underlying OEPC to CSC reprogramming may offer new insights to halt the conversion of premalignant cells into invasive carcinoma. HIGHLIGHTS: YAP and HPV E6-E7 reprogram oral epithelial progenitor cells into cancer stem cells. Single cell analyses reveal the transcriptional architecture of tumor initiation.CSC transcriptional programs distinguish normal tissue from carcinoma.CSC signatures are associated with poor head and neck cancer survival.

Intravital Imaging of Intestinal Intraepithelial Lymphocytes.

Intestinal intraepithelial lymphocytes (IEL) are a numerous population of T cells located within the epithelium of the small and large intestines, being more numerous in the small intestine (SI). They surveil this tissue by interacting with epithelial cells. Intravital microscopy is an important tool for visualizing the patrolling activity of IEL in the SI of live mice. Most IEL express CD8α; therefore, here we describe an established protocol of intravital imaging that tracks lymphocytes labeled with a CD8α-specific monoclonal antibody in the SI epithelium of live mice. We also describe data acquisition and quantification of the movement metrics, including mean speed, track length, displacement length, and paths for each CD8α+ IEL using the available software. The intravital imaging technique for measuring IEL movement will provide a better understanding of the role of IEL in homeostasis and protection from injury or infection in vivo.

SARS-CoV-2 Omicron (B.1.1.529) shows minimal neurotropism in a double-humanized mouse model.

Although severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) initially infects the respiratory tract, it also directly or indirectly affects other organs, including the brain. However, little is known about the relative neurotropism of SARS-CoV-2 variants of concern (VOCs), including Omicron (B.1.1.529), which emerged in November 2021 and has remained the dominant pathogenic lineage since then. To address this gap, we examined the relative ability of Omicron, Beta (B.1.351), and Delta (B.1.617.2) to infect the brain in the context of a functional human immune system by using human angiotensin-converting enzyme 2 (hACE2) knock-in triple-immunodeficient NGC mice with or without reconstitution with human CD34+ stem cells. Intranasal inoculation of huCD34+-hACE2-NCG mice with Beta and Delta resulted in productive infection of the nasal cavity, lungs, and brain on day 3 post-infection, but Omicron was surprisingly unique in its failure to infect either the nasal tissue or brain. Moreover, the same infection pattern was observed in hACE2-NCG mice, indicating that antiviral immunity was not responsible for the lack of Omicron neurotropism. In independent experiments, we demonstrate that nasal inoculation with Beta or with D614G, an ancestral SARS-CoV-2 with undetectable replication in huCD34+-hACE2-NCG mice, resulted in a robust response by human innate immune cells, T cells, and B cells, confirming that exposure to SARS-CoV-2, even without detectable infection, is sufficient to induce an antiviral immune response. Collectively, these results suggest that modeling of the neurologic and immunologic sequelae of SARS-CoV-2 infection requires careful selection of the appropriate SARS-CoV-2 strain in the context of a specific mouse model.

Treatment of pancreatic cancer with irreversible electroporation and intratumoral CD40 antibody stimulates systemic immune responses that inhibit liver metastasis in an orthotopic model.

BACKGROUND: Pancreatic cancer (PC) has a poor prognosis, and most patients present with either locally advanced or distant metastatic disease. Irreversible electroporation (IRE) is a non-thermal method of ablation used clinically in locally advanced PC, but most patients eventually develop distant recurrence. We have previously shown that IRE alone is capable of generating protective, neoantigen-specific immunity. Here, we aim to generate meaningful therapeutic immune effects by combining IRE with local (intratumoral) delivery of a CD40 agonistic antibody (CD40Ab). METHODS: KPC46 organoids were generated from a tumor-bearing male KrasLSL-G12D-p53LSL-R172H-Pdx-1-Cre (KPC) mouse. Orthotopic tumors were established in the pancreatic tail of B6/129 F1J mice via laparotomy. Mice were randomized to treatment with either sham laparotomy, IRE alone, CD40Ab alone, or IRE followed immediately by CD40Ab injection. Metastatic disease and immune infiltration in the liver were analyzed 14 days postprocedure using flow cytometry and multiplex immunofluorescence imaging with spatial analysis. Candidate neoantigens were identified by mutanome profiling of tumor tissue for ex vivo functional analyses. RESULTS: The combination of IRE+CD40 Ab improved median survival to greater than 35 days, significantly longer than IRE (21 days) or CD40Ab (24 days) alone (p<0.01). CD40Ab decreased metastatic disease burden, with less disease in the combination group than in the sham group or IRE alone. Immunohistochemistry of liver metastases revealed a more than twofold higher infiltration of CD8+T cells in the IRE+CD40 Ab group than in any other group (p<0.01). Multiplex immunofluorescence imaging revealed a 4-6 fold increase in the density of CD80+CD11c+ activated dendritic cells (p<0.05), which were spatially distributed throughout the tumor unlike the sham group, where they were restricted to the periphery. In contrast, CD4+FoxP3+ T-regulatory cells (p<0.05) and Ly6G+myeloid derived cells (p<0.01) were reduced and restricted to the tumor periphery in the IRE+CD40 Ab group. T-cells from the IRE+CD40 Ab group recognized significantly more peptides representing candidate neoantigens than did T-cells from the IRE or untreated control groups. CONCLUSIONS: IRE can induce local tumor regression and neoantigen-specific immune responses. Addition of CD40Ab to IRE improved dendritic cell activation and neoantigen recognition, while generating a strong systemic antitumor T-cell response that inhibited metastatic disease progression.

Hepatic pIgR-mediated secretion of IgA limits bacterial translocation and prevents ethanol-induced liver disease in mice.

OBJECTIVE: Alcohol-associated liver disease is accompanied by microbial dysbiosis, increased intestinal permeability and hepatic exposure to translocated microbial products that contribute to disease progression. A key strategy to generate immune protection against invading pathogens is the secretion of IgA in the gut. Intestinal IgA levels depend on the polymeric immunoglobulin receptor (pIgR), which transports IgA across the epithelial barrier into the intestinal lumen and hepatic canaliculi. Here, we aimed to address the function of pIgR during ethanol-induced liver disease. DESIGN: pIgR and IgA were assessed in livers from patients with alcohol-associated hepatitis and controls. Wild-type and pIgR-deficient (pIgR-/- ) littermates were subjected to the chronic-binge (NIAAA model) and Lieber-DeCarli feeding model for 8 weeks. Hepatic pIgR re-expression was established in pIgR-/- mice using adeno-associated virus serotype 8 (AAV8)-mediated pIgR expression in hepatocytes. RESULTS: Livers of patients with alcohol-associated hepatitis demonstrated an increased colocalisation of pIgR and IgA within canaliculi and apical poles of hepatocytes. pIgR-deficient mice developed increased liver injury, steatosis and inflammation after ethanol feeding compared with wild-type littermates. Furthermore, mice lacking pIgR demonstrated increased plasma lipopolysaccharide levels and more hepatic bacteria, indicating elevated bacterial translocation. Treatment with non-absorbable antibiotics prevented ethanol-induced liver disease in pIgR-/- mice. Injection of AAV8 expressing pIgR into pIgR-/- mice prior to ethanol feeding increased intestinal IgA levels and ameliorated ethanol-induced steatohepatitis compared with pIgR-/- mice injected with control-AAV8 by reducing bacterial translocation. CONCLUSION: Our results highlight that dysfunctional hepatic pIgR enhances alcohol-associated liver disease due to impaired antimicrobial defence by IgA in the gut.

Epithelial HVEM maintains intraepithelial T cell survival and contributes to host protection.

Intraepithelial T cells (IETs) are in close contact with intestinal epithelial cells and the underlying basement membrane, and they detect invasive pathogens. How intestinal epithelial cells and basement membrane influence IET survival and function, at steady state or after infection, is unclear. The herpes virus entry mediator (HVEM), a member of the TNF receptor superfamily, is constitutively expressed by intestinal epithelial cells and is important for protection from pathogenic bacteria. Here, we showed that at steady-state LIGHT, an HVEM ligand, binding to epithelial HVEM promoted the survival of small intestine IETs. RNA-seq and addition of HVEM ligands to epithelial organoids indicated that HVEM increased epithelial synthesis of basement membrane proteins, including collagen IV, which bound to ß1 integrins expressed by IETs. Therefore, we proposed that IET survival depended on ß1 integrin binding to collagen IV and showed that ß1 integrin-collagen IV interactions supported IET survival in vitro. Moreover, the absence of ß1 integrin expression by T lymphocytes decreased TCR αß+ IETs in vivo. Intravital microscopy showed that the patrolling movement of IETs was reduced without epithelial HVEM. As likely consequences of decreased number and movement, protective responses to Salmonella enterica were reduced in mice lacking either epithelial HVEM, HVEM ligands, or ß1 integrins. Therefore, IETs, at steady state and after infection, depended on HVEM expressed by epithelial cells for the synthesis of collagen IV by epithelial cells. Collagen IV engaged ß1 integrins on IETs that were important for their maintenance and for their protective function in mucosal immunity.

Effect of IL4 and IL10 on a human in vitro type 1 diabetes model.

We defined the effect of the anti-inflammatory cytokines IL4 and IL10 on an in vitro model of human T1D. After preincubation with IL4 or IL10, human islet microtissues were co-cultured with PBMC and proinflammatory cytokines for a few hours or for multiple days to assess acute and chronic effects. This resulted in an immune attack with infiltration of T cells into the islet, a loss of beta cell endocrine function, and an upregulation of HLA-I on the beta cells. HLA-I upregulation was associated with infiltration of T cells and both HLA-I expression and infiltration were associated with impaired insulin secretion. Preincubation with IL4 or IL10 did not preserve beta cell function but decreased infiltration of T cells. Our data support the hypothesis that a loss of beta cell endocrine function mediates an increase in beta cell specific antigen presentation. IL4 and IL10 failed to preserve beta cell endocrine function.

A humanized ß2 integrin knockin mouse reveals localized intra- and extravascular neutrophil integrin activation in vivo.

ß2 integrins are leukocyte-specific adhesion molecules that are essential for leukocyte recruitment. The lack of tools for reporting ß2 integrin activation in mice hindered the study of ß2 integrin-related immune responses in vivo. Here, we generated a humanized ß2 integrin knockin mouse strain by targeting the human ß2 integrin coding sequence into the mouse Itgb2 locus to enable imaging of ß2 integrin activation using the KIM127 (extension) and mAb24 (high-affinity) reporter antibodies. Using a CXCL1-induced acute inflammation model, we show the local dynamics of ß2 integrin activation in arresting neutrophils in vivo in venules of the mouse cremaster muscle. Activated integrins are highly concentrated in a small area at the rear of arresting neutrophils in vivo. In a high-dose lipopolysaccharide model, we find that ß2 integrins are activated in association with elevated neutrophil adhesion in lung and liver. Thus, these mice enable studies of ß2 integrin activation in vivo.

Tumor FAK orchestrates immunosuppression in ovarian cancer via the CD155/TIGIT axis.

High-grade serous ovarian cancer (HGSOC) is a lethal malignancy characterized by an immunosuppressive tumor microenvironment containing few tumor infiltrating lymphocytes (TILs) and an insensitivity to checkpoint inhibitor immunotherapies. Gains in the PTK2 gene encoding focal adhesion kinase (FAK) at Chr8 q24.3 occur in ∼70% of HGSOC tumors, and elevated FAK messenger RNA (mRNA) levels are associated with poor patient survival. Herein, we show that active FAK, phosphorylated at tyrosine-576 within catalytic domain, is significantly increased in late-stage HGSOC tumors. Active FAK costained with CD155, a checkpoint receptor ligand for TIGIT (T cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domains), in HGSOC tumors and a selective association between FAK and TIGIT checkpoint ligands were supported by patient transcriptomic database analysis. HGSOC tumors with high FAK expression were associated with low CD3 mRNA levels. Accordingly, late-stage tumors showed elevated active FAK staining and significantly lower levels of CD3+ TILs. Using the KMF (Kras, Myc, FAK) syngeneic ovarian tumor model containing spontaneous PTK2 (FAK) gene gains, the effects of tumor intrinsic genetic or oral small molecule FAK inhibitior (FAKi; VS-4718) were evaluated in vivo. Blocking FAK activity decreased tumor burden, suppressed ascites KMF-associated CD155 levels, and increased peritoneal TILs. The combination of FAKi with blocking TIGIT antibody (1B4) maintained elevated TIL levels and reduced TIGIT+ T regulatory cell levels, prolonged host survival, increased CXCL13 levels, and led to the formation of omental tertiary lymphoid structures. Collectively, our studies support FAK and TIGIT targeting as a rationale immunotherapy combination for HGSOC.

Oxidative stress promotes fibrosis in systemic sclerosis through stabilization of a kinase-phosphatase complex.

Systemic sclerosis (SSc) is a fibrotic autoimmune disease characterized by pathogenic activation of fibroblasts enhanced by local oxidative stress. The tyrosine phosphatase PTP4A1 was identified as a critical promoter of TGF-ß signaling in SSc. Oxidative stress is known to functionally inactivate tyrosine phosphatases. Here, we assessed whether oxidation of PTP4A1 modulates its profibrotic action and found that PTP4A1 forms a complex with the kinase SRC in scleroderma fibroblasts, but surprisingly, oxidative stress enhanced rather than reduced PTP4A1's association with SRC and its profibrotic action. Through structural assessment of the oxo-PTP4A1-SRC complex, we unraveled an unexpected mechanism whereby oxidation of a tyrosine phosphatase promotes its function through modification of its protein complex. Considering the importance of oxidative stress in the pathogenesis of SSc and fibrosis, our findings suggest routes for leveraging PTP4A1 oxidation as a potential strategy for developing antifibrotic agents.

Olfactory receptor 2 in vascular macrophages drives atherosclerosis by NLRP3-dependent IL-1 production.

Atherosclerosis is an inflammatory disease of the artery walls and involves immune cells such as macrophages. Olfactory receptors (OLFRs) are G protein­coupled chemoreceptors that have a central role in detecting odorants and the sense of smell. We found that mouse vascular macrophages express the olfactory receptor Olfr2 and all associated trafficking and signaling molecules. Olfr2 detects the compound octanal, which activates the NLR family pyrin domain containing 3 (NLRP3) inflammasome and induces interleukin-1ß secretion in human and mouse macrophages. We found that human and mouse blood plasma contains octanal, a product of lipid peroxidation, at concentrations sufficient to activate Olfr2 and the human ortholog olfactory receptor 6A2 (OR6A2). Boosting octanal levels exacerbated atherosclerosis, whereas genetic targeting of Olfr2 in mice significantly reduced atherosclerotic plaques. Our findings suggest that inhibiting OR6A2 may provide a promising strategy to prevent and treat atherosclerosis.

Microneedle-mediated Intratumoral Delivery of Anti-CTLA-4 Promotes cDC1-dependent Eradication of Oral Squamous Cell Carcinoma with Limited irAEs.

Head and neck squamous cell carcinoma (HNSCC) ranks sixth in cancer incidence worldwide and has a 5-year survival rate of only 63%. Immunotherapies-principally immune checkpoint inhibitors (ICI), such as anti-PD-1 and anti-CTLA-4 antibodies that restore endogenous antitumor T-cell immunity-offer the greatest promise for HNSCC treatment. Anti-PD-1 has been recently approved for first-line treatment of recurrent and metastatic HNSCC; however, less than 20% of patients show clinical benefit and durable responses. In addition, the clinical application of ICI has been limited by immune-related adverse events (irAE) consequent to compromised peripheral immune tolerance. Although irAEs are often reversible, they can become severe, prompting premature therapy termination or becoming life threatening. To address the irAEs inherent to systemic ICI therapy, we developed a novel, local delivery strategy based upon an array of soluble microneedles (MN). Using our recently reported syngeneic, tobacco-signature murine HNSCC model, we found that both systemic and local-MN anti-CTLA-4 therapy lead to >90% tumor response, which is dependent on CD8 T cells and conventional dendritic cell type 1 (cDC1). However, local-MN delivery limited the distribution of anti-CTLA-4 antibody from areas distal to draining lymphatic basins. Employing Foxp3-GFPDTR transgenic mice to interrogate irAEs in vivo, we found that local-MN delivery of anti-CTLA-4 protects animals from irAEs observed with systemic therapy. Taken together, our findings support the exploration of MN-intratumoral ICI delivery as a viable strategy for HNSCC treatment with reduced irAEs, and the opportunity to target cDC1s as part of multimodal treatment options to boost ICI therapy.

Bone Marrow Transplantation Rescues Monocyte Recruitment Defect and Improves Cystic Fibrosis in Mice.

Cystic fibrosis (CF) is an inherited life-threatening disease accompanied by repeated lung infections and multiorgan inflammation that affects tens of thousands of people worldwide. The causative gene, cystic fibrosis transmembrane conductance regulator (CFTR), is mutated in CF patients. CFTR functions in epithelial cells have traditionally been thought to cause the disease symptoms. Recent work has shown an additional defect: monocytes from CF patients show a deficiency in integrin activation and adhesion. Because monocytes play critical roles in controlling infections, defective monocyte function may contribute to CF progression. In this study, we demonstrate that monocytes from CFTRΔF508 mice (CF mice) show defective adhesion under flow. Transplanting CF mice with wild-type (WT) bone marrow after sublethal irradiation replaced most (60-80%) CF monocytes with WT monocytes, significantly improved survival, and reduced inflammation. WT/CF mixed bone marrow chimeras directly demonstrated defective CF monocyte recruitment to the bronchoalveolar lavage and the intestinal lamina propria in vivo. WT mice reconstituted with CF bone marrow also show lethality, suggesting that the CF defect in monocytes is not only necessary but also sufficient to cause disease. We also show that monocyte-specific knockout of CFTR retards weight gains and exacerbates dextran sulfate sodium-induced colitis. Our findings show that providing WT monocytes by bone marrow transfer rescues mortality in CF mice, suggesting that similar approaches may mitigate disease in CF patients.

Stimulation of a subset of natural killer T cells by CD103+ DC is required for GM-CSF and protection from pneumococcal infection.

Innate-like T cells, including invariant natural killer T cells, mucosal-associated invariant T cells, and γδ T cells, are present in various barrier tissues, including the lung, where they carry out protective responses during infections. Here, we investigate their roles during pulmonary pneumococcal infection. Following infection, innate-like T cells rapidly increase in lung tissue, in part through recruitment, but T cell antigen receptor activation and cytokine production occur mostly in interleukin-17-producing NKT17 and γδ T cells. NKT17 cells are preferentially located within lung tissue prior to infection, as are CD103+ dendritic cells, which are important both for antigen presentation to NKT17 cells and γδ T cell activation. Whereas interleukin-17-producing γδ T cells are numerous, granulocyte-macrophage colony-stimulating factor is exclusive to NKT17 cells and is required for optimal protection. These studies demonstrate how particular cellular interactions and responses of functional subsets of innate-like T cells contribute to protection from pathogenic lung infection.

Upregulation of HLA class II in pancreatic beta cells from organ donors with type 1 diabetes.

AIMS/HYPOTHESIS: We aimed to characterise and quantify the expression of HLA class II (HLA-II) in human pancreatic tissue sections and to analyse its induction in human islets. METHODS: We immunostained human pancreatic tissue sections from non-diabetic (n = 5), autoantibody positive (Aab+; n = 5), and type 1 diabetic (n = 5) donors, obtained from the Network of Pancreatic Organ Donors (nPOD), with HLA-II, CD68 and insulin. Each tissue section was acquired with a widefield slide scanner and then analysed with QuPath software. In total, we analysed 7415 islets that contained 338,480 cells. Widefield microscopy was further complemented by high resolution imaging of 301 randomly selected islets, acquired using a Zeiss laser scanning confocal (LSM880) to confirm our findings. Selected beta cells were acquired in enhanced resolution using LSM880 with an Airyscan detector. Further, we cultured healthy isolated human islets and reaggregated human islet microtissues with varying concentrations of proinflammatory cytokines (IFN-γ, TNF-α and IL-1ß). After proinflammatory cytokine culture, islet function was measured by glucose-stimulated insulin secretion, and HLA-I and HLA-II expression was subsequently evaluated with immunostaining or RNA sequencing. RESULTS: Insulin-containing islets (ICIs) of donors with type 1 diabetes had a higher percentage of HLA-II positive area (24.31%) compared with type 1 diabetic insulin-deficient islets (IDIs, 0.67%), non-diabetic (3.80%), and Aab+ (2.31%) donors. In ICIs of type 1 diabetic donors, 45.89% of the total insulin signal co-localised with HLA-II, and 27.65% of the islet beta cells expressed both HLA-II and insulin, while in non-diabetic and Aab+ donors 0.96% and 0.59% of the islet beta cells, respectively, expressed both markers. In the beta cells of donors with type 1 diabetes, HLA-II was mostly present in the cell cytoplasm, co-localising with insulin. In the experiments with human isolated islets and reaggregated human islets, we observed changes in insulin secretion upon stimulation with proinflammatory cytokines, as well as higher expression of HLA-II and HLA-I when compared with controls cultured with media, and an upregulation of HLA-I and HLA-II RNA transcripts. CONCLUSIONS/INTERPRETATION: After a long-standing controversy, we provide definitive evidence that HLA-II can be expressed by pancreatic beta cells from patients with type 1 diabetes. Furthermore, this upregulation can be induced in vitro in healthy isolated human islets or reaggregated human islets by treatment with proinflammatory cytokines. Our findings support a role for HLA-II in type 1 diabetes pathogenesis since HLA-II expressing beta cells can potentially become a direct target of autoreactive CD4+ lymphocytes.

Protein Kinase A in Human Retina: Differential Localization of Cß, Cα, RIIα, and RIIß in Photoreceptors Highlights Non-redundancy of Protein Kinase A Subunits.

Protein kinase A (PKA) signaling is essential for numerous processes but the subcellular localization of specific PKA regulatory (R) and catalytic (C) subunits has yet to be explored comprehensively. Additionally, the localization of the Cß subunit has never been spatially mapped in any tissue even though ∼50% of PKA signaling in neuronal tissues is thought to be mediated by Cß. Here we used human retina with its highly specialized neurons as a window into PKA signaling in the brain and characterized localization of PKA Cα, Cß, RIIα, and RIIß subunits. We found that each subunit presented a distinct localization pattern. Cα and Cß were localized in all cell layers (photoreceptors, interneurons, retinal ganglion cells), while RIIα and RIIß were selectively enriched in photoreceptor cells where both showed distinct patterns of co-localization with Cα but not Cß. Only Cα was observed in photoreceptor outer segments and at the base of the connecting cilium. Cß in turn, was highly enriched in mitochondria and was especially prominent in the ellipsoid of cone cells. Further investigation of Cß using RNA BaseScope technology showed that two Cß splice variants (Cß4 and Cß4ab) likely code for the mitochondrial Cß proteins. Overall, our data indicates that PKA Cα, Cß, RIIα, and RIIß subunits are differentially localized and are likely functionally non-redundant in the human retina. Furthermore, Cß is potentially important for mitochondrial-associated neurodegenerative diseases previously linked to PKA dysfunction.

An integrin αEß7-dependent mechanism of IgA transcytosis requires direct plasma cell contact with intestinal epithelium.

Efficient IgA transcytosis is critical for the maintenance of a homeostatic microbiota. In the canonical model, locally-secreted dimeric (d)IgA reaches the polymeric immunoglobulin receptor (pIgR) on intestinal epithelium via simple diffusion. A role for integrin αE(CD103)ß7 during transcytosis has not been described, nor its expression by intestinal B cell lineage cells. We found that αE-deficient (αE-/-) mice have a luminal IgA deficit, despite normal antibody-secreting cells (ASC) recruitment, local IgA production and increased pIgR expression. This deficit was not due to dendritic cell (DC)-derived retinoic acid (RA) nor class-switching defects, as stool from RAG-/- mice reconstituted with αE-/- B cells was also IgA deficient. Flow cytometric, ultrastructural and transcriptional profiling showed that αEß7-expressing ASC represent an undescribed subset of terminally-differentiated intestinal plasma cells (PC) that establishes direct cell to cell contact with intestinal epithelium. We propose that IgA not only reaches pIgR through diffusion, but that αEß7+ PC dock with E-cadherin-expressing intestinal epithelium to directly relay IgA for transcytosis into the intestinal lumen.