The co-evolution of our understanding of CD40 and inflammation

Ocrevus reduces TH40 cells, a biomarker of systemic inflammation, in relapsing multiple sclerosis (RMS) and in progressive multiple sclerosis (PMS)

Treating MS has been difficult. One successful drug is Ocrelizumab (anti-CD20), used for the chronic relapsing MS (RMS) and the progressive MS (PMS) forms. TH40 cells are pathogenic effector T cells that increase in percentage and numbers during chronic inflammation. Here we show that in the earliest MS course, clinically isolated syndrome (CIS), TH40 cells expand in number. In PMS TH40 cell numbers remain expanded demonstrating sustained chronic inflammation. In RMS TH40 cells were found in CSF and express CD20. Ocrelizumab reduced TH40 cells to healthy control levels in patients. During treatment inflammatory cytokine producing TH40 cells were decreased.

The potential role of mesenchymal stem cells in modulating antiageing process

Ageing and age-related diseases share some basic origin that largely converges on inflammation. Precisely, it boils down to a common pathway characterised by the appearance of a fair amount of proinflammatory cytokines known as inflammageing. Among the proposed treatment for antiageing, MSCs gained attention in recent years. Since mesenchymal stem cells (MSCs) can differentiate itself into a myriad of terminal cells, previously it was believed that these cells migrate to the site of injury and perform their therapeutic effect. However, with the more recent discovery of huge amounts of paracrine factors secreted by MSCs, it is now widely accepted that these cells do not engraft upon transplantation but rather unveil their benefits through excretion of bioactive molecules namely those involved in inflammatory and immunomodulatory activities. Conversely, the true function of these paracrine changes has not been thoroughly investigated all these years. Hence, this review will describe in detail on ways MSCs may capitalize its paracrine properties in modulating antiageing process. Through a comprehensive literature search various elements in the antiageing process, we aim to provide a novel treatment perspective of MSCs in antiageing related clinical conditions.

Targeting Type 1 Diabetes: Selective Approaches for New Therapies

The clinical onset of type 1 diabetes is characterized by the destruction of the insulin-producing β cells of the pancreas and is caused by autoantigen-induced inflammation (insulitis) of the islets of Langerhans. The current standard of care for type 1 diabetes mellitus patients allows for management of the disease with exogenous insulin, but patients eventually succumb to many chronic complications such as limb amputation, blindness, and kidney failure. New therapeutic approaches now on the horizon are looking beyond glycemic management and are evaluating new strategies from protecting and regenerating endogenous islets to treating the underlying autoimmunity through selective modulation of key immune cell populations. Currently, there are no effective treatments for the autoimmunity that causes the disease, and strategies that aim to delay or prevent the onset of the disease will play an important role in the future of diabetes research. In this review, we summarize many of the key efforts underway that utilize molecular approaches to selectively modulate this disease and look at new therapeutic paradigms that can transform clinical treatment.

CD40-mediated signalling influences trafficking, T-cell receptor expression, and T-cell pathogenesis, in the NOD model of type 1 diabetes

CD40 plays a critical role in the pathogenesis of type 1 diabetes (T1D). The mechanism of action, however, is undetermined, probably because CD40 expression has been grossly underestimated. CD40 is expressed on numerous cell types that now include T cells and pancreatic β cells. CD40⁺ CD4⁺ cells [T helper type 40 (TH40)] prove highly pathogenic in NOD mice and in translational human T1D studies. We generated BDC2.5.CD40^-/- and re-derived NOD.CD154^-/- mice to better understand the CD40 mechanism of action. Fully functional CD40 expression is required not only for T1D development but also for insulitis. In NOD mice, TH40 cell expansion in pancreatic lymph nodes occurs before insulitis and demonstrates an activated phenotype compared with conventional CD4⁺ cells, apparently regardless of antigen specificity. TH40 T-cell receptor (TCR) usage demonstrates increases in several Vα and Vβ species, particularly Vα3.2⁺ that arise early and are sustained throughout disease development. TH40 cells isolated from diabetic pancreas demonstrate a relatively broad TCR repertoire rather than restricted clonal expansions. The expansion of the Vα/Vβ species associated with diabetes depends upon CD40 signalling; NOD.CD154^-/- mice do not expand the same TCR species. Finally, CD40-mediated signals significantly increase pro-inflammatory Th1- and Th17-associated cytokines whereas CD28 co-stimulus alternatively promotes regulatory cytokines.

A CD40-targeted peptide controls and reverses type 1 diabetes in NOD mice

AIMS/HYPOTHESIS

The CD40-CD154 interaction directs autoimmune inflammation. Therefore, a long-standing goal in the treatment of autoimmune disease has been to control the formation of that interaction and thereby prevent destructive inflammation. Antibodies blocking CD154 are successful in mouse models of autoimmune disease but, while promising when used in humans, unfortunate thrombotic events have occurred, forcing the termination of those studies.

METHODS

To address the clinical problem of thrombotic events caused by anti-CD154 antibody treatment, we created a series of small peptides based on the CD154 domain that interacts with CD40 and tested the ability of these peptides to target CD40 and prevent type 1 diabetes in NOD mice.

RESULTS

We identified a lead candidate, the 15-mer KGYY15 peptide, which specifically targets CD40-positive cells in a size- and sequence-dependent manner. It is highly efficient in preventing hyperglycaemia in NOD mice that spontaneously develop type 1 diabetes. Importantly, KGYY15 can also reverse new-onset hyperglycaemia. KGYY15 is well tolerated and functions to control the cytokine profile of culprit Th40 effector T cells. The KGYY15 peptide is 87% homologous to the human sequence, suggesting that it is an important candidate for translational studies.

CONCLUSIONS/INTERPRETATION

Peptide KGYY15 constitutes a viable therapeutic option to antibody therapy in targeting the CD40-CD154 interaction in type 1 diabetes. Given the involvement of CD40 in autoimmunity in general, it will also be important to evaluate KGYY15 in the treatment of other autoimmune diseases. This alternative therapeutic approach opens new avenues of exploration in targeting receptor-ligand interactions.

Galectin-9 controls CD40 signaling through a Tim-3 independent mechanism and redirects the cytokine profile of pathogenic T cells in autoimmunity

While it has long been understood that CD40 plays a critical role in the etiology of autoimmunity, glycobiology is emerging as an important contributor. CD40 signaling is also gaining further interest in transplantation and cancer therapies. Work on CD40 signaling has focused on signaling outcomes and blocking of its ligand, CD154, while little is known about the actual receptor itself and its control. We demonstrated that CD40 is in fact several receptors occurring as constellations of differentially glycosylated forms of the protein that can sometimes form hybrid receptors with other proteins. An enticing area of autoimmunity is differential glycosylation of immune molecules leading to altered signaling. Galectins interact with carbohydrates on proteins to effect such signaling alterations. Studying autoimmune prone NOD and non-autoimmune BALB/c mice, here we reveal that in-vivo CD40 signals alter the glycosylation status of non-autoimmune derived CD4 T cells to resemble that of autoimmune derived CD4 T cells. Galectin-9 interacts with CD40 and, at higher concentrations, prevents CD40 induced proliferative responses of CD4^loCD40⁺ effector T cells and induces cell death through a Tim-3 independent mechanism. Interestingly, galectin-9, at lower concentrations, alters the surface expression of CD3, CD4, and TCR, regulating access to those molecules and thereby redirects the inflammatory cytokine phenotype and CD3 induced proliferation of autoimmune CD4^loCD40⁺ T cells. Understanding the dynamics of the CD40 receptor(s) and the impact of glycosylation status in immunity will gain insight into how to maintain useful CD40 signals while shutting down detrimental ones.

Amplified B lymphocyte CD40 signaling drives regulatory B10 cell expansion in mice

BACKGROUND

Aberrant CD40 ligand (CD154) expression occurs on both T cells and B cells in human lupus patients, which is suggested to enhance B cell CD40 signaling and play a role in disease pathogenesis. Transgenic mice expressing CD154 by their B cells (CD154(TG)) have an expanded spleen B cell pool and produce autoantibodies (autoAbs). CD22 deficient (CD22(-/-)) mice also produce autoAbs, and importantly, their B cells are hyper-proliferative following CD40 stimulation ex vivo. Combining these 2 genetic alterations in CD154(TG)CD22(-/-) mice was thereby predicted to intensify CD40 signaling and autoimmune disease due to autoreactive B cell expansion and/or activation.

METHODOLOGY/PRINCIPAL FINDINGS

CD154(TG)CD22(-/-) mice were assessed for their humoral immune responses and for changes in their endogenous lymphocyte subsets. Remarkably, CD154(TG)CD22(-/-) mice were not autoimmune, but instead generated minimal IgG responses against both self and foreign antigens. This paucity in IgG isotype switching occurred despite an expanded spleen B cell pool, higher serum IgM levels, and augmented ex vivo B cell proliferation. Impaired IgG responses in CD154(TG)CD22(-/-) mice were explained by a 16-fold expansion of functional, mature IL-10-competent regulatory spleen B cells (B10 cells: 26.7×10(6)±6 in CD154(TG)CD22(-/-) mice; 1.7×10(6)±0.4 in wild type mice, p<0.01), and an 11-fold expansion of B10 cells combined with their ex vivo-matured progenitors (B10+B10pro cells: 66×10(6)±3 in CD154(TG)CD22(-/-) mice; 6.1×10(6)±2 in wild type mice, p<0.01) that represented 39% of all spleen B cells.

CONCLUSIONS/SIGNIFICANCE

These results demonstrate for the first time that the IL-10-producing B10 B cell subset has the capacity to suppress IgG humoral immune responses against both foreign and self antigens. Thereby, therapeutic agents that drive regulatory B10 cell expansion in vivo may inhibit pathogenic IgG autoAb production in humans.

Primary immunodeficiency and autoimmunity: lessons from human diseases

Primary immunodeficiency diseases (PID) are a genetically heterogenous group of >150 disorders that affect distinct components of the innate and adaptive immune system and are often associated with autoimmune diseases. We describe PID affecting T-regulatory cells, complement and B cells or their products and discuss the possibility of a cause-effect relationship. The high concordance of T-regulatory cell defects to organ-specific autoimmune disease implies an obligatory role of these cells in maintaining tolerance to epithelial and endocrine tissues; the absence of central nervous system involvement may reflect immunological privilege. Congenital defects in C1q, C1r/s and C4 are strongly associated with systemic lupus erythematosus (SLE), and this pattern along with laboratory evidence suggests a major importance of classical pathway activity in safe elimination of immune complexes and prevention of immune complex disease (ICD). It is debatable whether this ICD is to be regarded as an autoimmune disease (resulting from a breakdown of immunological ignorance to antigens that are normally hidden), as autoantibodies may be absent, and tissue damage because of deposition of immune complexes could account for all of the pathology observed. Evidence for a causative link between primary antibody deficiencies and autoimmune disease is much less compelling and may in fact involve a common genetic background. However, arguments have also been made in favour of the notion that an intense antigen load as a result of recurrent or persistent infections may affect either tolerance or ignorance, e.g. by molecular mimicry or the presence of superantigens. Similar immunological mechanisms might account for the vast majority of autoimmune diseases.

CD40 glycoforms and TNF-receptors 1 and 2 in the formation of CD40 receptor(s) in autoimmunity

The CD40-CD154 dyad is an intensely studied field as is glycosylation status and both impact immunological functions and autoimmune conditions. CD40 has several isoforms, is modified by glycosylation, and trimerizes to form the functional receptor. We described a CD4(+)CD40(+) T cell (Th40) subset which is expanded in autoimmunity and is necessary and sufficient in transferring type 1 diabetes. Glycosylation impacts immunological events and T cells from autoimmune mouse strains express 30-40% less GlcNAc-branched N-glycans than T cells from non-autoimmune strains, a decrease known to activate T cells. Here we demonstrate that several CD40 receptor constellations exist on CD4 T cells. However, rather than containing different isoforms of CD40 they contain different glycoforms of isoform I. The glycoform profile is dependent on availability of CD154 and autoimmune NOD mice express a high level of a less glycosylated form. Interestingly, CD40 stimulation induces some CD40 receptor constellations that contain TNF-receptors 1 and 2 and targeting of those alters CD40 signaling outcomes in NOD Th40 cells. CD40-stimulation in vivo of non-autoimmune BALB/c mice expands the Th40 population and alters the CD40 glycoform profile of those cells to appear more like that of autoimmune prone NOD mice. Further understanding the dynamics and composition of the different CD40 receptor constellations will provide important insights into treatment options in autoimmunity.

Association of CD40 -1C/T polymorphism in the 5'-untranslated region and chronic obstructive pulmonary disease

BACKGROUND

Chronic inflammation of the airways and lung parenchyma plays a major role in the pathogenesis of chronic obstructive pulmonary disease (COPD). It is influenced by both environmental and genetic factors. CD40 signaling has been linked to pathogenic processes of chronic inflammatory diseases. After interaction with its ligand CD154 (CD40L), CD40 induces a broad variety of chronic inflammatory responses, inducing the release of inflammatory mediators. We investigated whether a CD40 gene (-1C/T) single nucleotide polymorphism (SNP) is associated with COPD in a Chinese population.

METHODS

We analyzed -1C/T SNP of the CD40 gene in 234 patients with COPD, and also in 312 controls using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing methods.

RESULTS

The frequency of CT and CT+CC of CD40 gene was significantly different from TT in the COPD group compared with the control group (for CT: OR=1.777, 95% CI: 1.117-2.826, p=0.015; for CT+CC: OR=1.614, 95% CI: 1.032-2.526, p=0.035). However, neither the allele frequency of CD40 nor the smoking and clinical stages in CD40 -1C/T genotypes frequency had significant differences between the COPD patients and control.

CONCLUSION

These findings suggest that the CD40 -1C/T polymorphism may contribute to the susceptibility to COPD in a Chinese population.