Efficacy and pharmacodynamic effect of anti-CD73 and anti-PD-L1 monoclonal antibodies in combination with cytotoxic therapy: observations from mouse tumor models.

CD73 is a cell surface 5'nucleotidase (NT5E) and key node in the catabolic process generating immunosuppressive adenosine in cancer. Using a murine monoclonal antibody surrogate of Oleclumab, we investigated the effect of CD73 inhibition in concert with cytotoxic therapies (chemotherapies as well as fractionated radiotherapy) and PD-L1 blockade. Our results highlight improved survival in syngeneic tumor models of colorectal cancer (CT26 and MC38) and sarcoma (MCA205). This therapeutic outcome was in part driven by cytotoxic CD8 T-cells, as evidenced by the detrimental effect of CD8 depleting antibody treatment of MCA205 tumor bearing mice treated with anti-CD73, anti-PD-L1 and 5-Fluorouracil+Oxaliplatin (5FU+OHP). We hypothesize that the improved responses are tumor microenvironment (TME)-driven, as suggested by the lack of anti-CD73 enhanced cytopathic effects mediated by 5FU+OHP on cell lines in vitro. Pharmacodynamic analysis, using imaging mass cytometry and RNA-sequencing, revealed noteworthy changes in specific cell populations like cytotoxic T cells, B cells and NK cells in the CT26 TME. Transcriptomic analysis highlighted treatment-related modulation of gene profiles associated with an immune response, NK and T-cell activation, T cell receptor signaling and interferon (types 1 & 2) pathways. Inclusion of comparator groups representing the various components of the combination allowed deconvolution of contribution of the individual therapeutic elements; highlighting specific effects mediated by the anti-CD73 antibody with respect to immune-cell representation, chemotaxis and myeloid biology. These pre-clinical data reflect complementarity of adenosine blockade with cytotoxic therapy, and T-cell checkpoint inhibition, and provides new mechanistic insights in support of combination therapy.

The psychometric properties of a new oral health illness perception measure for adults aged 62 years and older.

BACKGROUND: Based on the Common-Sense Model of Self-Regulation (CSM), a new integrated Illness Perception Questionnaire Revised for Dental Use in Older/Elder Adults (IPQ-RDE) was developed for single and multiple dental conditions. This study describes psychometric properties of the IPQ-RDE for adults 62 years and older. METHODS: Participants (n = 198) living in 16 subsidized housing facilities completed the IPQ-RDE and a questionnaire assessing their socio-demographics, frequency of dental visits, perceived condition of teeth/gums, depression, social support, and oral health quality of life (OHQOL). Participants received dental screening for presence/absence of teeth, coronal and root caries, and periodontitis. The 43-item IPQ-RDE was tested for internal (construct, discriminant) and external validity (concurrent, construct, discriminant, predictive) and reliability (internal consistency). RESULTS: Confirmatory factor analysis demonstrated that a ten-factor model in accordance with the CSM framework (identity, consequences, control, timeline, illness coherence, treatment burden, prioritization, causal relationship, activity restriction, emotional representations) had good construct validity based on significant factor loadings and acceptable model fit (RMSEA = 0.065, CFI = 0.902). Edentulous participants had significantly higher mean factor scores (inaccurate perception) for overall IPQ-RDE and four constructs indicating concurrent validity. Discriminant validity was suggested by non-relationship with external measures (education, dental visit frequency). Predictive validity was indicated by the negative correlation of most constructs with OHQOL suggesting that inaccurate perception was related to lower quality of life. Internal consistency of eight IPQ-RDE constructs was excellent (Cronbach's alpha > 0.73). CONCLUSIONS: The IPQ-RDE is a valid and reliable new measure for assessing older adult's perception of dental conditions. It can be an important tool for oral health behavioral research to restructure older adult's perception of dental conditions, and subsequently prevent tooth loss and improve oral health quality of life.

A GPBAR1 (TGR5) small molecule agonist shows specific inhibitory effects on myeloid cell activation in vitro and reduces experimental autoimmune encephalitis (EAE) in vivo.

GPBAR1 is a G protein-coupled receptor that is activated by certain bile acids and plays an important role in the regulation of bile acid synthesis, lipid metabolism, and energy homeostasis. Recent evidence suggests that GPBAR1 may also have important effects in reducing the inflammatory response through its expression on monocytes and macrophages. To further understand the role of GPBAR1 in inflammation, we generated a novel, selective, proprietary GPBAR1 agonist and tested its effectiveness at reducing monocyte and macrophage activation in vitro and in vivo. We have used this agonist, together with previously described agonists to study agonism of GPBAR1, and shown that they can all induce cAMP and reduce TLR activation-induced cytokine production in human monocytes and monocyte-derived macrophages in vitro. Additionally, through the usage of RNA sequencing (RNA-Seq), we identified a select set of genes that are regulated by GPBAR1 agonism during LPS activation. To further define the in vivo role of GPBAR1 in inflammation, we assessed GPBAR1 expression and found high levels on circulating mouse monocytes. Agonism of GPBAR1 reduced LPS-induced cytokine production in mouse monocytes ex vivo and serum cytokine levels in vivo. Agonism of GPBAR1 also had profound effects in the experimental autoimmune encephalomyelitis (EAE) mouse model of multiple sclerosis, where monocytes play an important role. Mice treated with the GPBAR1 agonist exhibited a significant reduction in the EAE clinical score which correlated with reduced monocyte and microglial activation and reduced trafficking of monocytes and T cells into the CNS. These data confirm the importance of GPBAR1 in controlling monocyte and macrophage activation in vivo and support the rationale for selective agonists of GPBAR1 in the treatment of inflammatory diseases.

A high-throughput scintillation proximity assay for sphingosine-1-phosphate lyase.

The emergence of sphingosine-1-phosphate lyase (SPL) as a promising therapeutic target for inflammatory diseases has heightened interest in the identification of small molecules that modulate its activity. The enzymatic activity of SPL is typically measured using radiometric or fluorescence-based assays that require a lipid extraction step, or by direct quantitation of reaction products using mass spectrometry (MS). To facilitate testing large numbers of compounds to identify SPL modulators, we developed a robust scintillation proximity assay (SPA) that is compatible with high-throughput screening (HTS). This assay employs recombinant human full-length SPL in insect cell membrane preparations to catalyze the conversion of biotinylated aminosphingosine-1-[(33)P]phosphate (S1(33)P-biotin) to trans-2-hexadecenal-biotin and ethanolamine [(33)P]phosphate. To validate the SPA and confirm the fidelity of its measurement of SPL enzyme activity, we developed a Rapid-Fire MS method that quantitates nonradiolabeled S1P-biotin. In addition, we developed a simple, scalable method to produce S1(33)P-biotin in quantities sufficient for HTS. The optimized SPA screen in 384-well microplates produced a mean plate-wise Z'-statistic of 0.58 across approximately 3,000 plates and identified several distinct structural classes of SPL inhibitor. Among the inhibitors that the screen identified was one compound with an IC50 of 1.6 µM in the SPA that induced dose-dependent lymphopenia in mice.

Circulating monocytes are reduced by sphingosine-1-phosphate receptor modulators independently of S1P3.

Sphingosine-1-phosphate (S1P) receptors are critical for lymphocyte egress from secondary lymphoid organs, and S1P receptor modulators suppress lymphocyte circulation. However, the role of S1P receptors on monocytes is less clear. To elucidate this, we systematically evaluated monocytes in rats and mice, both in naive and inflammatory conditions, with S1P receptor modulators FTY720 and BAF312. We demonstrate that S1P receptor modulators reduce circulating monocytes in a similar time course as lymphocytes. Furthermore, total monocyte numbers were increased in the spleen and bone marrow, suggesting that S1P receptor modulation restricts egress from hematopoietic organs. Monocytes treated ex vivo with FTY720 had reduced CD40 expression and TNF-α production, suggesting a direct effect on monocyte activation. Similar reductions in protein expression and cytokine production were also found in vivo. Suppression of experimental autoimmune encephalomyelitis in mice and rats by FTY720 correlated with reduced numbers of lymphocytes and monocytes. These effects on monocytes were independent of S1P3, as treatment with BAF312, a S1P1,4,5 modulator, led to similar results. These data reveal a novel role for S1P receptors on monocytes and offer additional insights on the mechanism of action of S1P receptor modulators in disease.

Pathogenic mechanisms and experimental models of multiple sclerosis.

Multiple sclerosis (MS) is a devastating autoimmune disease that affects more than 1 million people worldwide and severely compromises motor and sensory function through demyelination and axonal loss. This review covers current therapies, lessons learned from failed clinical trials, genetic susceptibility, key cell types involved, animal models, gene expression, and biomarker information. The current first-line therapies for MS include the type I interferons (IFN-I) and glatiramer acetate (GA) but because of their limited effectiveness new therapeutic modalities are required. Tysabri is an anti very late antigen-4 antibody that antagonizes the migration of multiple cell types and appears more efficacious as compared to the IFNs or GA. Tysabri blocks the transmigration of T cells and monocytes, which indicates that blocking multiple cell types may increase the effectiveness of the therapy. However, this therapy may increase the risk of progressive multifocal leukoencephalopathy. The major cell types hypothesized to be pathogenic include T cells and antigen-presenting cells, including B cells. The correlation of the animal model experimental autoimmune encephalomyelitis (EAE) of MS and its predictive value to determine efficacy in the clinic appears limited. However, all current therapies do demonstrate efficacy in EAE models. There are also examples of mechanisms that have worked in EAE but have failed in the clinic, such as the TNFα antagonists and anti-p40 (a subunit of IL-12 and IL-23). The MS field would benefit if clinical biomarkers were available to monitor clinical efficacy. The etiology of MS remains elusive but additional understanding of mechanisms involved in the pathogenesis of MS may guide us to more effective treatment and management of this autoimmune disease.

Autoantibodies against type I interferons as an additional diagnostic criterion for autoimmune polyendocrine syndrome type I.

CONTEXT: In autoimmune polyendocrinopathy syndrome type I (APS-I), mutations in the autoimmune regulator gene (AIRE) impair thymic self-tolerance induction in developing T cells. The ensuing autoimmunity particularly targets ectodermal and endocrine tissues, but chronic candidiasis usually comes first. We recently reported apparently APS-I-specific high-titer neutralizing autoantibodies against type I interferons in 100% of Finnish and Norwegian patients, mainly with two prevalent AIRE truncations. OBJECTIVES: Because variability in clinical features and age at onset in APS-I frequently results in unusual presentations, we prospectively checked the diagnostic potential of anti-interferon antibodies in additional APS-I panels with other truncations or rare missense mutations and in disease controls with chronic mucocutaneous candidiasis (CMC) but without either common AIRE mutation. DESIGN: The study was designed to detect autoantibodies against interferon-alpha2 and interferon-omega in antiviral neutralization assays. SETTING AND PATIENTS: Patients included 14 British/Irish, 15 Sardinian, and 10 Southern Italian AIRE-mutant patients with APS-I; also 19 other patients with CMC, including four families with cosegregating thyroid autoimmunity. OUTCOME: The diagnostic value of anti-interferon autoantibodies was assessed. RESULTS: We found antibodies against interferon-alpha2 and/or interferon-omega in all 39 APS-I patients vs. zero of 48 unaffected relatives and zero of 19 British/Irish CMC patients. Especially against interferon-omega, titers were nearly always high, regardless of the exact APS-I phenotype/duration or AIRE genotype, including 12 different AIRE length variants or 10 point substitutions overall (n=174 total). Strikingly, in one family with few typical APS-I features, these antibodies cosegregated over three generations with autoimmune hypothyroidism plus a dominant-negative G228W AIRE substitution. CONCLUSIONS: Otherwise restricted to patients with thymoma and/or myasthenia gravis, these precocious persistent antibodies show 98% or higher sensitivity and APS-I specificity and are thus a simpler diagnostic option than detecting AIRE mutations.

Death, adaptation and regulation: the three pillars of immune tolerance restrict the risk of autoimmune disease caused by molecular mimicry.

Extensive cross-reactivity in T cell receptor (TCR) recognition of peptide-MHC (pMHC) complexes seems to be essential to give sufficient immune surveillance against invading pathogens. This carries with it an inherent risk that T cells activated during a response to clear an infection can, perhaps years later, respond to a self pMHC of sufficient similarity. This lies at the heart of the molecular mimicry theory. Here we discuss our studies on the disease-causing potential of altered peptide ligands (APL) based on the sequence of a single autoantigenic epitope, the Ac1-9 peptide of myelin basic protein that induces experimental autoimmune encephalomyelitis in mice. These show that the window of similarity to self for induction of disease by cross-reactive non-self peptides is actually quite restricted. We show that each of the three pillars of immune tolerance (death, anergy/adaptation and regulation) has a role in limiting the risk of molecular mimicry by maintaining a threshold for harm.

Fas-mediated death and sensory adaptation limit the pathogenic potential of autoreactive T cells after strong antigenic stimulation.

The ability of autoreactive T cells to induce autoimmune pathology is dependent on their ability to respond to the level of autoantigen presented in the target organ. Emerging evidence suggests that at the population level, T cell sensitivity for self can be reduced by deletion of those cells bearing high-affinity T cell receptors (TCRs) or by sensory adaptation of individual cells. Here, we have investigated the mechanisms that prevent the induction of experimental autoimmune encephalomyelitis (EAE) when myelin basic protein (MBP)-reactive T cells are exposed to a strong, antigenic stimulus. Stimulation of MBP-reactive TCR transgenic T cells with a superagonist peptide led to extensive activation-induced cell death (AICD) through Fas signaling. Using T cells lacking Fas, we found that disruption of this deletional mechanism only partially increased EAE in response to superagonist, failing to restore susceptibility to the level found in response to the wild-type MBP peptide. A significant fraction of the MBP-reactive T cells was able to avoid AICD in response to superagonist, but these cells had a reduced sensitivity for an antigen that correlated with elevated levels of CD5. Therefore, when TCR affinity is fixed, autoreactive T cell sensitivity can be shifted to below a threshold for harm by a combination of AICD and sensory adaptation.

Activation thresholds determine susceptibility to peptide-induced tolerance in a heterogeneous myelin-reactive T cell repertoire.

Altered peptide ligands (APL) with increased MHC-binding properties are highly effective at inducing T cell tolerance after systemic administration in soluble form, preventing experimental autoimmune encephalomyelitis (EAE) induced with the myelin basic protein (MBP) Ac1-9 peptide. We have previously described a diverse Ac1-9-reactive T cell repertoire with differing TCR affinities. A remaining question is what proportion of this repertoire is silenced by peptide therapy? Here, we show that the sensitivity of a T cell to peptide-induced tolerance is related to its avidity for native Ac1-9. These data provide new evidence that self-reactive T cells bearing low-affinity TCRs are able to escape therapeutic induction of tolerance.

Modification of peptide interaction with MHC creates TCR partial agonists.

We report the creation of TCR partial agonists by the novel approach of manipulating the interaction between immunogenic peptide and MHC. Amino acids at MHC anchor positions of the I-E(k)-restricted hemoglobin (64-76) and moth cytochrome c (88-103) peptides were exchanged with MHC anchor residues from the low affinity class II invariant chain peptide (CLIP), resulting in antigenic peptides with altered affinity for MHC class II. Several low affinity peptides were identified as TCR partial agonists, as defined by the ability to stimulate cytolytic function but not proliferation. For example, a peptide containing methionine substitutions at positions one and nine of the I-E(k) binding motif acted as a partial agonist for two hemoglobin-reactive T cell clones (PL.17 and 3.L2). The identical MHC anchor substitutions in moth cytochrome c (88-103) also created a partial agonist for a mCC-reactive T cell (A.E7). Thus, peptides containing MHC anchor modifications mediated similar T cell responses regardless of TCR fine specificity or antigen reactivity. This data contrasts with the unique specificity among individual clones demonstrated using traditional altered peptide ligands containing substitutions at TCR contact residues. In conclusion, we demonstrate that altering the MHC anchor residues of the immunogenic peptide can be a powerful method to create TCR partial agonists.