Dysregulation of CD4+ and CD8+ resident memory T, myeloid, and stromal cells in steroid-experienced, checkpoint inhibitor colitis

BACKGROUND

Colitis caused by checkpoint inhibitors (CPI) is frequent and is treated with empiric steroids, but CPI colitis mechanisms in steroid-experienced or refractory disease are unclear.

METHODS

Using colon biopsies and blood from predominantly steroid-experienced CPI colitis patients, we performed multiplexed single-cell transcriptomics and proteomics to nominate contributing populations.

RESULTS

CPI colitis biopsies showed enrichment of CD4+resident memory (RM) T cells in addition to CD8+ RM and cytotoxic CD8+ T cells. Matching T cell receptor (TCR) clonotypes suggested that both RMs are progenitors that yield cytotoxic effectors. Activated, CD38+ HLA-DR+ CD4+ RM and cytotoxic CD8+ T cells were enriched in steroid-experienced and a validation data set of steroid-naïve CPI colitis, underscoring their pathogenic potential across steroid exposure. Distinct from ulcerative colitis, CPI colitis exhibited perturbed stromal metabolism (NAD+, tryptophan) impacting epithelial survival and inflammation. Endothelial cells in CPI colitis after anti-TNF and anti-cytotoxic T-lymphocyte-associated antigen 4 (anti-CTLA-4) upregulated the integrin α4β7 ligand molecular vascular addressin cell adhesion molecule 1 (MAdCAM-1), which may preferentially respond to vedolizumab (anti-α4β7).

CONCLUSIONS

These findings nominate CD4+ RM and MAdCAM-1+ endothelial cells for targeting in specific subsets of CPI colitis patients.

Single-cell and spatial multi-omics highlight effects of anti-integrin therapy across cellular compartments in ulcerative colitis

Ulcerative colitis (UC) is driven by immune and stromal subsets, culminating in epithelial injury. Vedolizumab (VDZ) is an anti-integrin antibody that is effective for treating UC. VDZ is known to inhibit lymphocyte trafficking to the intestine, but its broader effects on other cell subsets are less defined. To identify the inflammatory cells that contribute to colitis and are affected by VDZ, we perform single-cell transcriptomic and proteomic analyses of peripheral blood and colonic biopsies in healthy controls and patients with UC on VDZ or other therapies. Here we show that VDZ treatment is associated with alterations in circulating and tissue mononuclear phagocyte (MNP) subsets, along with modest shifts in lymphocytes. Spatial multi-omics of formalin-fixed biopsies demonstrates trends towards increased abundance and proximity of MNP and fibroblast subsets in active colitis. Spatial transcriptomics of archived specimens pre-treatment identifies epithelial-, MNP-, and fibroblast-enriched genes related to VDZ responsiveness, highlighting important roles for these subsets in UC.

Single-cell and spatial multi-omics highlight effects of anti-integrin therapy across cellular compartments in ulcerative colitis

Ulcerative colitis (UC) is driven by immune and stromal subsets, culminating in epithelial injury. Vedolizumab (VDZ) is an anti-integrin antibody that is effective for treating UC. VDZ is known to inhibit lymphocyte trafficking to the intestine, but its broader effects on other cell subsets are less defined. To identify the inflammatory cells that contribute to colitis and are affected by VDZ, we performed single-cell transcriptomic and proteomic analyses of peripheral blood and colonic biopsies in healthy controls and patients with UC on VDZ or other therapies. Here we show that VDZ treatment is associated with alterations in circulating and tissue mononuclear phagocyte (MNP) subsets, along with modest shifts in lymphocytes. Spatial multi-omics of formalin-fixed biopsies demonstrates trends towards increased abundance and proximity of MNP and fibroblast subsets in active colitis. Spatial transcriptomics of archived specimens pre-treatment identifies epithelial-, MNP-, and fibroblast-enriched genes related to VDZ responsiveness, highlighting important roles for these subsets in UC.

A20 Restricts NOS2 Expression and Intestinal Tumorigenesis in a Mouse Model of Colitis-Associated Cancer

BACKGROUND AND AIMS

Colon cancer can occur sporadically or in the setting of chronic inflammation, such as in patients with inflammatory bowel disease. We previously showed that A20, a critical negative regulator of tumor necrosis factor signal transduction, could regulate sporadic colon cancer development. In this report, we investigate whether A20 also acts as a tumor suppressor in a model of colitis-associated cancer.

METHODS

Colitis and colitis-associated tumors were induced in wild-type and A20 intestinal epithelial cell-specific knockout (A20dIEC) mice using dextran sodium sulfate and azoxymethane. Clinicopathologic markers of inflammation were assessed in conjunction with colonic tumor burden. Gene expression analyses and immunohistochemistry were performed on colonic tissue and intestinal enteroids. Nitric oxide (NO) production and activity were assessed in whole colonic lysates and mouse embryonic fibroblasts.

RESULTS

A20dIEC mice develop larger tumors after treatment with dextran sodium sulfate and azoxymethane than wild-type mice. In addition to elevated markers of inflammation, A20dIEC mice have significantly enhanced expression of inducible nitric oxide synthase (iNOS), a well-known driver of neoplasia. Enhanced iNOS expression is associated with the formation of reactive nitrogen species and DNA damage. Loss of A20 also enhances NO-dependent cell death directly.

CONCLUSION

Mechanistically, we propose that A20 normally restricts tumor necrosis factor-induced nuclear factor kappa B-dependent production of iNOS in intestinal epithelial cells, thereby protecting against colitis-associated tumorigenesis. We also propose that A20 plays a direct role in regulating NO-dependent cell death.

Vedolizumab Antagonizes MAdCAM-1-Dependent Human Placental Cytotrophoblast Adhesion and Invasion In Vitro

BACKGROUND

Anti-α4β7 (Vedolizumab) treats inflammatory bowel disease (IBD) by blocking the interaction between integrin α4β7 on leukocytes and mucosal addressin cell-adhesion molecule-1 (MAdCAM-1) on the gut endothelium. Women with IBD often require continuing biologic therapy during pregnancy to avoid disease flare. To date, there have been no reports of an increase in adverse events with Vedolizumab use during pregnancy. Notably, integrins play a major role in human placental development during pregnancy. It is unknown whether Vedolizumab disrupts placental cell (cytotrophoblast) invasion and/or adhesion by blocking interactions with MAdCAM-1. We therefore investigated human placental expression of MAdCAM-1, the role of MAdCAM-1/α4β7 interactions in cytotrophoblast invasion/adhesion in vitro, and whether Vedolizumab administration in vivo alters the placental structure.

METHODS

Histological sections of placentas from normal pregnancies were evaluated for MAdCAM-1 expression by immunofluorescence. The impacts of Vedolizumab or anti-integrin β7 on human cytotrophoblast invasion and adhesion were assessed. Histology results from term placentas of 2 patients with IBD receiving Vedolizumab were compared to those of untreated healthy controls.

RESULTS

Placental MAdCAM-1 expression was predominantly associated with invading extravillous cytotrophoblasts at the maternal-fetal interface. Treatment of isolated primary cytotrophoblasts with Vedolizumab or anti-integrin β7 significantly reduced Matrigel invasion, adherence to a MAdCAM-1-coated substrate, and interactions with HuT-78 cells. Placentas from 2 Vedolizumab-treated patients with IBD exhibited pronounced pathologic features as compared to healthy control specimens.

CONCLUSIONS

This study revealed a previously unrecognized role for α4β7 and MAdCAM-1 in human placentation. More clinical and histological data from Vedolizumab-treated pregnant patients will be necessary to determine whether this medication poses any risk to the mother and fetus.

Intestinal inflammation alters the antigen-specific immune response to a skin commensal

Resident microbes in skin and gut predominantly impact local immune cell function during homeostasis. However, colitis-associated neutrophilic skin disorders suggest possible breakdown of this compartmentalization with disease. Using a model wherein neonatal skin colonization by Staphylococcus epidermidis facilitates generation of commensal-specific tolerance and CD4⁺ regulatory T cells (Tregs), we ask whether this response is perturbed by gut inflammation. Chemically induced colitis is accompanied by intestinal expansion of S. epidermidis and reduces gut-draining lymph node (dLN) commensal-specific Tregs. It also results in reduced commensal-specific Tregs in skin and skin-dLNs and increased skin neutrophils. Increased CD4⁺ circulation between gut and skin dLN suggests that the altered cutaneous response is initiated in the colon, and resistance to colitis-induced effects in Cd4^creIl1r1^fl/fl mice implicate interleukin (IL)-1 in mediating the altered commensal-specific response. These findings provide mechanistic insight into observed connections between inflammatory skin and intestinal diseases.

Microbial signals, MyD88, and lymphotoxin drive TNF-independent intestinal epithelial tissue damage

Anti-TNF antibodies are effective for treating patients with inflammatory bowel disease (IBD), but many patients fail to respond to anti-TNF therapy, highlighting the importance of TNF-independent disease. We previously demonstrated that acute deletion of 2 IBD susceptibility genes, A20 (Tnfaip3) and Abin-1 (Tnip1), in intestinal epithelial cells (IECs) sensitized mice to both TNF-dependent and TNF-independent death. Here we show that TNF-independent IEC death after A20 and Abin-1 deletion was rescued by germ-free derivation or deletion of MyD88, while deletion of Trif provided only partial protection. Combined deletion of Ripk3 and Casp8, which inhibits both apoptotic and necroptotic death, completely protected against death after acute deletion of A20 and Abin-1 in IECs. A20- and Abin-1–deficient IECs were sensitized to TNF-independent, TNFR1-mediated death in response to lymphotoxin α (LTα) homotrimers. Blockade of LTα in vivo reduced weight loss and improved survival when combined with partial deletion of MyD88. Biopsies of inflamed colon mucosa from patients with IBD exhibited increased LTA and IL1B expression, including a subset of patients with active colitis on anti-TNF therapy. These data show that microbial signals, MyD88, and LTα all contribute to TNF-independent intestinal injury.

A20 in dendritic cells restrains intestinal anti-bacterial peptide expression and preserves commensal homeostasis

Microbial dysbiosis commonly occurs in patients with inflammatory bowel diseases (IBD). Exogenous causes of dysbiosis such as antibiotics and diet are well described, but host derived causes are understudied. A20 is a potent regulator of signals triggered by microbial pattern molecules, and A20 regulates susceptibility to intestinal inflammation in mice and in humans. We now report that mice lacking A20 expression in dendritic cells, A20FL/FL CD11c-Cre mice (or A20dDC mice), spontaneously develop colitogenic intestinal dysbiosis that is evident upon weaning and precedes the onset of colitis. Intestines from A20dDC mice express increased amounts of Reg3β and Reg3γ, but not Ang4. A20 deficient DCs promote gut microbiota perturbation in the absence of adaptive lymphocytes. Moreover, A20 deficient DCs directly induce expression of Reg3β and Reg3γ but not Ang 4 in normal intestinal epithelial cell enteroid cultures in the absence of other cell types. These findings reveal a pathophysiological pathway in which defective expression of an IBD susceptibility gene in DCs drives aberrant expression of anti-bacterial peptides and luminal dysbiosis that in turn confers host susceptibility to intestinal inflammation.

Effect of I-scan Electronic Chromoendoscopy on Detection of Adenomas During Colonoscopy

BACKGROUND & AIMS

I-scan is an electronic chromoendoscopy technology that improves resolution of epithelial and mucosal surfaces and vessels. We performed a randomized controlled trial to compare detection of adenomas by i-scan vs standard high-definition white-light (HDWL) colonoscopy.

METHODS

From February 1 through December 31, 2017, 740 outpatients (50-75 years old) undergoing screening and surveillance for colorectal neoplasia were randomly assigned to groups that received colonoscopies with i-scan 1 (surface and contrast enhancement) or HDWL. When lesions and polyps were detected, endoscopists could switch between i-scan 1 and HDWL imaging to confirm their finding; polyps were collected and analyzed by histology. The primary outcome was adenoma detection rate (ADR, proportion of subjects with at least 1 adenoma of any size); secondary outcomes included detection of sessile serrated polyps and neoplasias, along with location, size, and morphology of polyps. We performed intent to treat and per-protocol analyses (on 357 patients evaluated by i-scan and 358 evaluated by HDWL colonoscopy) to assess the primary and secondary outcomes.

RESULTS

There were no differences in baseline characteristics between the groups. In the intent to treat analysis, the ADR was significantly higher in the i-scan 1 group (47.2%) than in the HDWL colonoscopy group (37.7%) (P = .01). In the per-protocol analysis, the ADR in the i-scan 1 group (47.6%) was also significantly higher than in the HDWL group (37.2%) (P = .005), but this effect was not consistent among all endoscopists. There was no difference between groups in detection of sessile serrated polyps. However, the rate of neoplasia detection was significantly higher in the i-scan 1 group (56.4%) than in the than the HDWL group (46.1%) (P = .005). In secondary analyses, the increase in ADR was associated with improved detection of diminutive flat adenomas in the right colon.

CONCLUSION

In a prospective randomized trial, higher proportions of patients with adenomas were identified in a group that underwent colonoscopy with i-scan 1 than in a group evaluated by HDWL colonoscopy. This effect was mainly due to improved detection of diminutive, flat right sided adenomas. I-scan 1 technology may benefit some endoscopists. ClinicalTrials.gov no: NCT02811419.

A20 and ABIN-1 synergistically preserve intestinal epithelial cell survival

A20 (TNFAIP3) and ABIN-1 (TNIP1), two candidate inflammatory bowel disease (IBD) susceptibility genes, preserve intestinal homeostasis by cooperatively restricting intestinal epithelial cell death. A20 and ABIN-1 synergistically restrict both TNF-dependent and TNF-independent cell death.

A20 (TNFAIP3) and ABIN-1 (TNIP1) are candidate susceptibility genes for inflammatory bowel disease and other autoimmune or inflammatory diseases, but it is unclear how these proteins interact in vivo to prevent disease. Here we show that intestinal epithelial cell (IEC)-specific deletion of either A20 or ABIN-1 alone leads to negligible IEC loss, whereas simultaneous deletion of both A20 and ABIN-1 leads to rapid IEC death and mouse lethality. Deletion of both A20 and ABIN-1 from enteroids causes spontaneous cell death in the absence of microbes or hematopoietic cells. Studies with enteroids reveal that A20 and ABIN-1 synergistically restrict death by inhibiting TNF-induced caspase 8 activation and RIPK1 kinase activity. Inhibition of RIPK1 kinase activity alone, or caspase inhibition combined with RIPK3 deletion, abrogates IEC death by blocking both apoptosis and necroptosis in A20 and ABIN-1 double-deficient cells. These data show that the disease susceptibility proteins A20 and ABIN-1 synergistically prevent intestinal inflammation by restricting IEC death and preserving tissue integrity.

Anti-TNF and thiopurine therapy in pregnant IBD patients does not significantly alter a panel of B-cell and T-cell subsets in 1-year-old infants

Objectives

Infants exposed to combination therapy with anti-tumor necrosis factor (anti-TNF) agents and thiopurines may exhibit increased infections at 1 year of age compared to unexposed infants. We hypothesized that this increased risk of infection is due to abnormal development of the newborn immune system.

Methods

We immunophenotyped B-cell and T-cell subsets using multiparameter flow cytometry in 1-year-old infants whose mothers were exposed to therapeutic agents for IBD. We analyzed samples from infants exposed to infliximab (IFX) or adalimumab (ADA) monotherapy (IFX/ADA, n = 11), certolizumab pegol (CZP) monotherapy (CZP, n = 4), IFX or ADA plus thiopurine combination therapy (IFX/ADA + IM, n = 4), and CZP plus thiopurine combination therapy (CZP + IM, n = 2).

Results

Percentages of B cells, CD4⁺ T helper cells, T regulatory cells (T_regs), and CD8⁺ cytotoxic T cells, were similar among the groups. Infants exposed to combination therapy (IFX/ADA + IM) exhibited trends toward fewer CD27⁺ B cells, switched memory B cells, plasmablasts, interferon gamma (IFNγ)-producing CD4⁺ and CD8⁺ T cells, and CCR5⁺CD4⁺ T cells, but these did not reach statistical significance.

Conclusions

Multiparameter immunophenotyping of major B-cell and T-cell subsets suggests that the adaptive newborn immune system develops largely unaltered after exposure to combination therapy as compared to anti-TNF monotherapy.

A20 upregulation during treated HIV disease is associated with intestinal epithelial cell recovery and function

TRIAL REGISTRATION

ClinicalTrials.gov Clinical Trial NCT00594880.

Ubiquitin-Modifying Enzymes and Regulation of the Inflammasome

Ubiquitin and ubiquitin-modifying enzymes play critical roles in a wide variety of intracellular signaling pathways. Inflammatory signaling cascades downstream of TNF, TLR agonists, antigen receptor cross-linking, and cytokine receptors, all rely on ubiquitination events to direct subsequent immune responses. In the past several years, inflammasome activation and subsequent signal transduction have emerged as an excellent example of how ubiquitin signals control inflammatory responses. Inflammasomes are multiprotein signaling complexes that ultimately lead to caspase activation and release of the interleukin-1 (IL-1) family members, IL-1β and IL-18. Inflammasome activation is critical for the host's defense against pathogens, but dysregulation of inflammasomes may contribute to the pathogenesis of multiple diseases. Ultimately, understanding how various ubiquitin interacting proteins control inflammatory signaling cascades could provide new pathways for therapeutic intervention. Here we review specific ubiquitin-modifying enzymes and ubiquitination events that orchestrate inflammatory responses, with an emphasis on the NLRP3 inflammasome.

The Ubiquitin Binding Protein TAX1BP1 Mediates Autophagasome Induction and the Metabolic Transition of Activated T Cells

During immune responses, naive T cells transition from small quiescent cells to rapidly cycling cells. We have found that T cells lacking TAX1BP1 exhibit delays in growth of cell size and cell cycling. TAX1BP1-deficient T cells exited G₀ but stalled in S phase, due to both bioenergetic and biosynthetic defects. These defects were due to deficiencies in mTOR complex formation and activation. These mTOR defects in turn resulted from defective autophagy induction. TAX1BP1 binding of LC3 and GABARAP via its LC3-interacting region (LIR), but not its ubiquitin-binding domain, supported T cell proliferation. Supplementation of TAX1BP1-deficient T cells with metabolically active L-cysteine rescued mTOR activation and proliferation but not autophagy. These studies reveal that TAX1BP1 drives a specialized form of autophagy, providing critical amino acids that activate mTOR and enable the metabolic transition of activated T cells.

Measurement of mast cell surface molecules by high-throughput immunophenotyping using transcription (HIT)

Here we describe the application of a highly multiplexed proteomic assay, called HIT (high-throughput immunophenotyping using transcription), to analyze human mast cell surface antigens at rest and during stimulation. HIT allows analysis of up to 100 analytes, including surface antigens and intracellular phosphoproteins, transcription factors, and cytokines, in a single experiment. Briefly, anti-mouse monovalent Fab fragments are covalently conjugated with barcoded oligonucleotides to generate a panel of conjugates. The oligonucleotide-Fab fragment conjugates are bound to monoclonal primary antibodies, creating a cocktail of up to 48 unique barcoded primary antibodies. As few as 100,000 mast cells are stained with the cocktail and the barcodes of the bound primary antibodies are amplified by in vitro transcription with fluorescently labeled NTPs. The resulting barcoded transcripts are quantified using a microarray spotted with oligonucleotides that are complementary to the barcoded transcripts. Differences in levels of the barcoded transcripts correlate well with actual protein levels and are capable of detecting stimulation-dependent changes in protein levels. HIT is an invaluable, broad-spectrum approach for characterizing mast cell surface antigens, signaling molecules, transcription factors, and cytokines.

The U1-snRNP complex: structural properties relating to autoimmune pathogenesis in rheumatic diseases

The U1 small nuclear ribonucleoprotein particle (snRNP) is a target of autoreactive B cells and T cells in several rheumatic diseases including systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD). We propose that inherent structural properties of this autoantigen complex, including common RNA-binding motifs, B and T-cell epitopes, and a unique stimulatory RNA molecule, underlie its susceptibility as a target of the autoimmune response. Immune mechanisms that may contribute to overall U1-snRNP immunogenicity include epitope spreading through B and T-cell interactions, apoptosis-induced modifications, and toll-like receptor (TLR) activation through stimulation by U1-snRNA. We conclude that understanding the interactions between U1-snRNP and the immune system will provide insights into why certain patients develop anti-U1-snRNP autoimmunity, and more importantly how to effectively target therapies against this autoimmune response.

Naive CD4 t cell proliferation is controlled by mammalian target of rapamycin regulation of GRAIL expression

In this study, we demonstrate that the E3 ubiquitin ligase gene related to anergy in lymphocytes (GRAIL) is expressed in quiescent naive mouse and human CD4 T cells and has a functional role in inhibiting naive T cell proliferation. Following TCR engagement, CD28 costimulation results in the expression of IL-2 whose signaling through its receptor activates the Akt-mammalian target of rapamycin (mTOR) pathway. Activation of mTOR allows selective mRNA translation, including the epistatic regulator of GRAIL, Otubain-1 (Otub1), whose expression results in the degradation of GRAIL and allows T cell proliferation. The activation of mTOR appears to be the critical component of IL-2R signaling regulating GRAIL expression. CTLA4-Ig treatment blocks CD28 costimulation and resultant IL-2 expression, whereas rapamycin and anti-IL-2 treatment block mTOR activation downstream of IL-2R signaling. Thus, all three of these biotherapeutics inhibit mTOR-dependent translation of mRNA transcripts, resulting in blockade of Otub1 expression, maintenance of GRAIL, and inhibition of CD4 T cell proliferation. These observations provide a mechanistic pathway sequentially linking CD28 costimulation, IL-2R signaling, and mTOR activation as important requirements for naive CD4 T cell proliferation through the regulation of Otub1 and GRAIL expression. Our findings also extend the role of GRAIL beyond anergy induction and maintenance, suggesting that endogenous GRAIL regulates general cell cycle and proliferation of primary naive CD4 T cells.

Protein microarrays with carbon nanotubes as multicolor Raman labels

The current sensitivity of standard fluorescence-based protein detection limits the use of protein arrays in research and clinical diagnosis. Here, we use functionalized, macromolecular single-walled carbon nanotubes (SWNTs) as multicolor Raman labels for highly sensitive, multiplexed protein detection in an arrayed format. Unlike fluorescence methods, Raman detection benefits from the sharp scattering peaks of SWNTs with minimal background interference, affording a high signal-to-noise ratio needed for ultra-sensitive detection. When combined with surface-enhanced Raman scattering substrates, the strong Raman intensity of SWNT tags affords protein detection sensitivity in sandwich assays down to 1 fM--a three-order-of-magnitude improvement over most reports of fluorescence-based detection. We use SWNT Raman tags to detect human autoantibodies against proteinase 3, a biomarker for the autoimmune disease Wegener's granulomatosis, diluted up to 10(7)-fold in 1% human serum. SWNT Raman tags are not subject to photobleaching or quenching. By conjugating different antibodies to pure (12)C and (13)C SWNT isotopes, we demonstrate multiplexed two-color SWNT Raman-based protein detection.

Protein microarrays with carbon nanotubes as multicolor Raman labels

The current sensitivity of standard fluorescence-based protein detection limits the use of protein arrays in research and clinical diagnosis. Here, we use functionalized, macromolecular single-walled carbon nanotubes (SWNTs) as multicolor Raman labels for highly sensitive, multiplexed protein detection in an arrayed format. Unlike fluorescence methods, Raman detection benefits from the sharp scattering peaks of SWNTs with minimal background interference, affording a high signal-to-noise ratio needed for ultra-sensitive detection. When combined with surface-enhanced Raman scattering substrates, the strong Raman intensity of SWNT tags affords protein detection sensitivity in sandwich assays down to 1 fM--a three-order-of-magnitude improvement over most reports of fluorescence-based detection. We use SWNT Raman tags to detect human autoantibodies against proteinase 3, a biomarker for the autoimmune disease Wegener's granulomatosis, diluted up to 10(7)-fold in 1% human serum. SWNT Raman tags are not subject to photobleaching or quenching. By conjugating different antibodies to pure (12)C and (13)C SWNT isotopes, we demonstrate multiplexed two-color SWNT Raman-based protein detection.

Cytokines secreted in response to Toll-like receptor ligand stimulation modulate differentiation of human Th17 cells

OBJECTIVE

Th17 cells (interleukin-17 [IL-17]-secreting T helper cells) have been implicated in the pathogenesis of rheumatoid arthritis and other autoimmune diseases, but the soluble factors that influence human Th17 differentiation have yet to be fully elucidated. This study was undertaken to investigate the hypothesis that the cytokines secreted by human peripheral blood mononuclear cells (PBMCs) in response to a subset of Toll-like receptor (TLR) ligands would influence Th17 polarization.

METHODS

Supernatants from human PBMCs treated with a panel of TLR agonists were tested for their ability to induce de novo IL-17 production in naive T helper cells. Multiplex cytokine analysis was used to identify candidate cytokines for subsequent blocking and sufficiency experiments.

RESULTS

Conditioned media from PBMCs stimulated with TLR-4 or TLR-8/7 agonists, but not from those stimulated with TLR-2/1, -3, or -9 agonists, evoked robust secretion of IL-17 by T helper cells, independent of coculture with antigen-presenting cells. Multiplex analysis of 22 cytokines and chemokines identified a 6-factor cytokine signature that significantly correlated with IL-17-inducing activity. T cell activation in the presence of recombinant IL-1beta, IL-6, and IL-23 reconstituted robust IL-17 production, and this was enhanced by transforming growth factor beta (TGFbeta). IL-6 suppressed the expression of forkhead box P3 and reversed TGFbeta-mediated inhibition of T cell proliferation, but did not trigger IL-17 secretion. IL-17 production was completely abrogated by anti-IL-1 or IL-1 receptor antagonist and partially inhibited by anti-IL-6, anti-IL-2, or exogenous retinoic acid, but not by anti-tumor necrosis factor alpha. IL-1beta and IL-6 independently induced IL-21 secretion, but the presence of IL-21 alone was not sufficient for IL-17 production.

CONCLUSION

These results indicate that ligation of a subset of TLRs generates proinflammatory cytokines that combine to potentiate human Th17 differentiation.

Free-solution oligonucleotide separation in nanoscale channels

In this paper, we report an experimental study of electrokinetic transport and separation of double-stranded deoxyribonucleic acid (dsDNA) oligonucleotides in custom-fabricated fused-silica nanochannels filled with a gel-free sodium borate aqueous buffer. Mixtures of fluorescently labeled dsDNA molecules in the range of 10-100 base pair (bp), fluorescein, and fluorescein-12-UTP (UTP) were separated in less than 120 s in channels of depth ranging from 40 to 1560 nm. We varied the channel depth and background buffer concentration to achieve a 0.006-0.2 range of Debye length-to-channel-half-depth ratio (lambdaD/h), and a 0.004-1.7 range of the ratio of length of dsDNA molecule to channel half-depth (l/h). We find observed oligonucleotide migration times depend on both l/h and lambdaD/h. Electrophoretic mobility estimates agree well with published (micrometer-scale channel) values for background electrolyte (BGE) concentrations greater than approximately 10 mM. At BGE concentrations of 1 and 5 mM, mobility estimates in our nanochannels are higher than published values. Of the cases studied, the highest separation sensitivities were achieved in 100 nm channels with 1-10 mM ion density buffers. Potential applications of this technology include rapid small-scale sequencing and other fluorescence-based oligonucleotide separation and detection assays.

A new two-color Fab labeling method for autoantigen protein microarrays

Antigen microarrays hold great promise for profiling the humoral immune response in the settings of autoimmunity, allergy and cancer. This approach involves immobilizing antigens on a slide surface and then exposing the array to biological fluids containing immunoglobulins. Although these arrays have proven extremely useful as research tools, they suffer from several sources of variability. To address these issues, we have developed a new two-color Fab labeling method that allows two samples to be applied simultaneously to the same array. This straightforward labeling approach improves reproducibility and reliably detects changes in autoantibody concentrations. Using this technique we profiled serum from a mouse model of systemic lupus erythematosus (SLE) and detected both expected and previously unrecognized reactivities. The improved labeling and detection method described here overcomes several problems that have hindered antigen microarrays and should facilitate translation to the clinical setting.