Synergistic T cell signaling by 41BB and CD28 is optimally achieved by membrane proximal positioning within parallel chimeric antigen receptors

Second generation (2G) chimeric antigen receptors (CARs) contain a CD28 or 41BB co-stimulatory endodomain and elicit remarkable efficacy in hematological malignancies. Third generation (3G) CARs extend this linear blueprint by fusing both co-stimulatory units in series. However, clinical impact has been muted despite compelling evidence that co-signaling by CD28 and 41BB can powerfully amplify natural immune responses. We postulate that effective dual co-stimulation requires juxta-membrane positioning of endodomain components within separate synthetic receptors. Consequently, we designed parallel (p)CARs in which a 2G (CD28+CD3ζ) CAR is co-expressed with a 41BB-containing chimeric co-stimulatory receptor. We demonstrate that the pCAR platform optimally harnesses synergistic and tumor-dependent co-stimulation to resist T cell exhaustion and senescence, sustaining proliferation, cytokine release, cytokine signaling, and metabolic fitness upon repeated stimulation. When engineered using targeting moieties of diverse composition, affinity, and specificity, pCAR T cells consistently elicit superior anti-tumor activity compared with T cells that express traditional linear CARs.

Augmented Expansion of Treg Cells From Healthy and Autoimmune Subjects via Adult Progenitor Cell Co-Culture

Recent clinical experience has demonstrated that adoptive regulatory T (Treg) cell therapy is a safe and feasible strategy to suppress immunopathology via induction of host tolerance to allo- and autoantigens. However, clinical trials continue to be compromised due to an inability to manufacture a sufficient Treg cell dose. Multipotent adult progenitor cells (MAPC^Ⓡ) promote Treg cell differentiation in vitro, suggesting they may be repurposed to enhance ex vivo expansion of Tregs for adoptive cellular therapy. Here, we use a Good Manufacturing Practice (GMP) compatible Treg expansion platform to demonstrate that MAPC cell-co-cultured Tregs (MulTreg) exhibit a log-fold increase in yield across two independent cohorts, reducing time to target dose by an average of 30%. Enhanced expansion is coupled to a distinct Treg cell-intrinsic transcriptional program characterized by elevated expression of replication-related genes (CDK1, PLK1, CDC20), downregulation of progenitor and lymph node-homing molecules (LEF1 CCR7, SELL) and induction of intestinal and inflammatory tissue migratory markers (ITGA4, CXCR1) consistent with expression of a gut homing (CCR7lo β₇hi) phenotype. Importantly, we find that MulTreg are more readily expanded from patients with autoimmune disease compared to matched Treg lines, suggesting clinical utility in gut and/or T helper type1 (Th1)-driven pathology associated with autoimmunity or transplantation. Relative to expanded Tregs, MulTreg retain equivalent and robust purity, FoxP3 Treg-Specific Demethylated Region (TSDR) demethylation, nominal effector cytokine production and potent suppression of Th1-driven antigen specific and polyclonal responses in vitro and xeno Graft vs Host Disease (xGvHD) in vivo. These data support the use of MAPC cell co-culture in adoptive Treg therapy platforms as a means to rescue expansion failure and reduce the time required to manufacture a stable, potently suppressive product.

Approaches for refining and furthering the development of CAR-based T cell therapies for solid malignancies

Introduction: Chimeric antigen receptor-engineered T-cells typically use the binding domains of antibodies to target cytotoxicity toward tumors. This approach has produced great efficacy against selected hematological cancers, but benefit in solid tumors has been limited. Characteristically, the microenvironment in solid tumors restricts CAR T cell function, thereby limiting success. Enhancing efficacy will depend on novel target discovery to refine specificity and reduce toxicity. Additionally, overcoming immunosuppressive mechanisms may be achieved by altering the structure of the CAR itself, together with ancillary gene expression or additional therapeutic interventions.Areas covered: Herein, the authors discuss approaches for refining and further developing CAR T cell therapies specifically for use with solid malignancies. The authors survey the existing literature and provide perspectives for the future.Expert opinion: Pronounced efficacy in solid tumors will likely require combination therapies, targeting both the tumor itself and associated immunosuppressive mechanisms. Future exploration of CAR T cell therapies for solid tumors is likely to incorporate next-generation designs that couple more precise targeting of cancer-associated targets with enhanced potency and resistance to exhaustion.

Regulatory T cell dysfunction in type 1 diabetes: what's broken and how can we fix it?

Type 1 diabetes is an autoimmune disease characterised by the destruction of insulin producing beta cells in the pancreas. Whilst it remains unclear what the original triggering factors for this destruction are, observations from the natural history of human type 1 diabetes, including incidence rates in twins, suggest that the disease results from a combination of genetic and environmental factors. Whilst many different immune cells have been implicated, including members of the innate and adaptive immune systems, a view has emerged over the past 10 years that beta cell damage is mediated by the combined actions of CD4⁺ and CD8⁺ T cells with specificity for islet autoantigens. In health, these potentially pathogenic T cells are held in check by multiple regulatory mechanisms, known collectively as 'immunological tolerance'. This raises the question as to whether type 1 diabetes develops, at least in part, as a result of a defect in one or more of these control mechanisms. Immunological tolerance includes both central mechanisms (purging of the T cell repertoire of high-affinity autoreactive T cells in the thymus) and peripheral mechanisms, a major component of which is the action of a specialised subpopulation of T cells, known as regulatory T cells (Tregs). In this review, we highlight the evidence suggesting that a reduction in the functional capacity of different Treg populations contributes to disease development in type 1 diabetes. We also address current controversies regarding the putative causes of this defect and discuss strategies to correct it as a means to reduce or prevent islet destruction in a clinical setting.

Pimecrolimus 1% cream for oral erosive lichen planus: a 6-week randomized, double-blind, vehicle-controlled study with a 6-week open-label extension to assess efficacy and safety

OBJECTIVE

To assess the efficacy and safety of topical pimecrolimus 1% cream in the treatment of oral erosive lichen planus.

DESIGN

A 6-week randomized, double-blind, vehicle-controlled phase followed by a 6-week open-label phase.

SETTING

Outpatients of the Department of Dermatology, University of Utah.

PATIENTS

Twenty-one patients with oral erosive lichen planus were randomized and treated with either pimecrolimus 1% cream or vehicle cream.

INTERVENTION

Pimecrolimus 1% cream, or its vehicle, were applied twice daily for 6 weeks to each side of the mouth with a 2×2 inch gauze pad folded in half and placed directly on the erosive lesion.

MAIN OUTCOME MEASURES

Efficacy was based on clinical evaluation of Investigator's Global Assessment (IGA) of the overall severity of the disease, erythema, measurement of the size of any target erosion in millimetres, and assessment of spontaneous pain. Blood levels of pimecrolimus were monitored in all subjects on day 0 and repeated on day 7.

RESULTS

Pimecrolimus 1% cream was superior to vehicle cream in reducing mean IGA, pain, and erosion size. For the vehicle group that entered the open-label phase, pimecrolimus 1% cream improved the mean IGA, pain, erosion size, and erythema. Pimecrolimus levels were detected in nine out of 10 of the pimecrolimus-treated subjects. These levels were consistently low. The pimecrolimus cream was well-tolerated. No clinically relevant, drug-related adverse events were reported.

CONCLUSION

Pimecrolimus 1% cream was superior to vehicle in reducing pain, erythema, decreasing erosion size, and improving overall severity of disease when compared with vehicle treatment.

Elevation of IgA anti-epidermal transglutaminase antibodies in dermatitis herpetiformis

BACKGROUND

Dermatitis herpetiformis (DH) is a papulovesicular eruption caused by ingestion of gluten. It is characterized by the deposition of IgA in the dermal papillae. IgA antibodies directed at tissue transglutaminase (TG2) are elevated in gluten-sensitive diseases including DH and coeliac disease (CD). More recently, antibodies directed at epidermal transglutaminase (TG3) were identified in patients with DH, and this may be the dominant autoantigen in this disease.

OBJECTIVES

To measure IgA antibodies to TG3 and TG2 in patients with DH and CD, and control populations.

METHODS

Serum IgA antibodies against TG2 and TG3 were measured from adults with DH, adults and children with CD, patients with psoriasis, adult Red Cross blood donors, and paediatric controls.

RESULTS

Patients with DH and CD had elevated levels of IgA anti-TG2 antibodies compared with control populations. The levels in the patients with DH and adults with CD were similar. IgA anti-TG2 antibodies were higher in the children with CD compared with adults with DH and CD, and with control populations. Patients with DH and adults with CD had elevated levels of IgA anti-TG3 antibodies compared with children with CD and control populations. There was a trend towards higher levels in the patients with DH compared with adults with CD.

CONCLUSIONS

IgA antibodies to TG3 are elevated in patients with DH and adults with CD. The progressive expansion of the epitope-binding profile of IgA antitransglutaminase antibodies in patients with CD may explain the development of DH in patients with undiagnosed CD during their adult life.

Evidence for mating of the "asexual" yeast Candida albicans in a mammalian host

Since its classification nearly 80 years ago, the human pathogen Candida albicans has been designated as an asexual yeast. In this report, we describe the construction of C. albicans strains that were subtly altered at the mating-type-like (MTL) locus, a cluster of genes that resembles the mating-type loci of other fungi. These derivatives were capable of mating after inoculation into a mammalian host. C. albicans is a diploid organism, but most of the mating products isolated from a mouse host were tetrasomic for the two chromosomes that could be rigorously monitored and, overall, exhibited substantially higher than 2n DNA content. These observations demonstrated that C. albicans can recombine sexually.

A familial case of P-ANCA glomerulonephritis presenting in a father and daughter

Antineutrophil cytoplasmic antibodies (ANCA) have proved to be useful serological markers for a subset of vasculitic diseases, including Wegener's granulomatosis, microscopic polyangiitis, and the Churg-Strauss syndrome. The pathogenesis of the ANCA vasculitides remains less clear, including what role, if any, genetic factors play in the expression of ANCA-associated diseases. Familial cases of systemic vasculitis have been reported, and a number of studies have addressed HLA associations of Wegener's and microscopic polyangiitis, but the results have been confusing and inconsistent. We report the first case of P-ANCA-positive vasculitis presenting in a Native American father and daughter. Both patients had systemic vasculitis and were P-ANCA positive with anti-myeloperoxidase (MPO) antibodies.

Identification of a mating type-like locus in the asexual pathogenic yeast Candida albicans

Candida albicans, the most prevalent fungal pathogen in humans, is thought to lack a sexual cycle. A set of C. albicans genes has been identified that corresponds to the master sexual cycle regulators a1, alpha1, and alpha2 of the Saccharomyces cerevisiae mating-type (MAT) locus. The C. albicans genes are arranged in a way that suggests that these genes are part of a mating type-like locus that is similar to the mating-type loci of other fungi. In addition to the transcriptional regulators a1, alpha1, and alpha2, the C. albicans mating type-like locus contains several genes not seen in other fungal MAT loci, including those encoding proteins similar to poly(A) polymerases, oxysterol binding proteins, and phosphatidylinositol kinases.

Vasoactive agonists do not change the caliber of retinal capillaries of the rat

The pericytes of the retinal capillaries are considered to be contractile cells, based on indirect evidence. We attempted to detect pericyte contractility directly using a morphometric method following intravitreal injection of vasoconstricting (endothelin-1, norepinephrine) and vasodilating (forskolin, prostaglandin E1) agonists in rats. The technique involved measuring changes in the ratio of the (lumenal perimeter x mean lumenal radius) to the lumenal area (rP/A ratio, which we defined as "caliber"). Following intravitreal injection of endothelin-1 or norepinephrine there is an ophthalmoscopically visible constriction of the larger retinal arterioles. This constriction is also clearly demonstrable morphometrically (P = 0.001 for endothelin-1 and P = 0.047 for norepinephrine). However, neither for the vasoconstricting nor for the vasodilating agonists is there evidence of a significant change of the caliber of the capillaries. At least in the retina of the rat, therefore, we have no evidence that the pericytes perform a contractile function that alters flow in the capillaries.