Immunomodulatory therapies for type 1diabetes mellitus (T1DM) Nafiseh Esmaeil Ph.D of Immunology

usually diagnosed in children and young adults, and was previously known as juvenile diabetes. Only 5% of people with diabetes have this form of the disease. In type 1 diabetes, the body does not produce insulin. T1D Results from a cell mediated autoimmune attack against pancreatic β cells that causes insulin deficiency. One-fourth of cases are also diagnosed in adults.

T2D Type 2 diabetes is the most common form of diabetes. Your body does not use insulin properly. This is called insulin resistance. At first, your pancreas makes extra insulin to make up for it But, over time it isn't able to keep up and can't make enough insulin to keep your blood glucose at normal levels.

Differences between T1D & T2D

Etiology Of T1D Genetic Environmental factors like infectious Viruses, Chemicals Humoral and cell-mediated immune mechanisms, special CD4+ T cells

Aetiology of type 1 diabetes: Breakdown of immune tolerance

Therapy

Because of the ocular, circulatory, cardiovascular, and neurological risks associated with hyperglycemia. Treatments that prevent the pathologic autoimmunity from destroying pancreatic tissue is preferable to long-term management of symptoms by insulin replacement therapy Because the use of exogenous insulin can not match the precision of endogenous insulin secretion.

Immunotherapy treatment strategies Immunoprevention aims to either prevent the emergence of autoimmunity (Primary prevention) or to reverse it (Secondary prevention) before the development of symptomatic type 1 diabetes. Immunoreversal aims to intervene at the time of diagnosis to reverse autoimmunity and to preserve residual β-cell function and establish tolerance to β-cells (Tertiary prevention). Ideally, immunomodulatory therapy would induce prolonged remission from type 1 diabetes and achieve cure.

Autoimmune Treatment Treatment Antigen- specific immunotherapies Monoclonal Antibodies T-reg therapy

Antigen-specific immunomodulation The aim of antigen-specific therapies is to restore tolerance and achieve remission of autoimmunity in type 1 diabetes. The exact mechanism of how antigen-specific tolerance is achieved is not clear, but induction of regulatory T cells has been postulated.

Antigen- Specific Immunotherapies Glutamic acid decarboxylase (GAD) Insulin HSP 60

Glutamic acid decarboxylase (GAD) The GAD enzyme is responsible for the production of the inhibitory neurotransmitter GABA (γ‑amino butyric acid) from glutamate. The GAD65 isoform of the protein was identified as a major autoantigen in type 1 diabetes. In individuals at risk of developing and in patients with type 1 diabetes, both autoreactive T cells and autoantibodies to GAD65 are present .

Glutamic acid decarboxylase (GAD) In most cases, the materialization of GAD65-specific antibodies occurs before the destruction of β cells. GAD65 vaccines, as demonstrated by preclinical studies, have the possibility to halt T1DM progression in non-obese diabetic (NOD) mice. GAD65 has demonstrated moderate success in human trials. In 2005 Phase II trial with Latent Autoimmune Diabets in Adults (LADA) patients ) Two 20µg subcutaneous doses 1 month Increases C-peptide at 24 weeks & increases in CD4+ CD25 + T reg cells. In 2008 Phase II trial with recent onset T1D children A slower decline C-peptide was observed in the GAD-alum group compared to the placebo In 2011 Phase III trial, these positive findings unfortunately could not be reproduced for reasons not entirely understood. Suggesting that the autoimmune process is more susceptible to GAD-based modulatory therapy if initiated at an earlier stage.

Insulin Many studies have utilized insulin and proinsulin peptides in an attempt to prevent islet autoimmunity In 2005 The first diabetes prevention trial A low dose of oral insulin For first degree relatives of T1DM patients Did not delay the development of overt diabetes

Insulin Other Trials: An oral insulin Phase I/II clinical trial of children who are genetically susceptible to T1DM has recently been published.(2015) In Low Dose: Insulin-responsive T cells displayed regulatory T-cell features after oral insulin treatment High dose of oral insulin (67.5 mg) positive immune response can be induced. A Phase I trial patients receiving immunization with insulin B chain has been shown to be safe in T1DM patients, and despite inducing IL-10-producing Tregs, no preservation of C-peptide was observed. (2009) A separate Phase II study tested NBI-6024, which is an altered peptide ligand of the insulin B chain. Recently diagnosed T1DM patients received 3 doses of NBI-6024 or placebo. At 24 months, the decline in C-peptide in three treatment groups was not different with the placebo group. (2009) Nasal administration of insulin has also been studied in preventing onset of T1DM in 224 children with HLA haplotypes that increase the predisposition for developing T1DM. Progression to diabetes was not different between nasal insulin and placebo groups. (2008)

Is a 60,000 kDa protein that to be expressed in the secretory granules of β cells Function as an autoantigen that plays an important role in signaling the immune attack on β cells. HSP-60 Diapep277, which is a short 24 amino acid peptide that stems from human HSP60, has been tested on both NOD mice and humans as a potential ASI. Diapep277 has shown promising results in preclinical and Phase II clinical studies A Phase III trial and thus the future of DiaPep277 remains uncertain

DiaPep277 DiaPep277 is a protein corresponding to amino-acid positions 437–460(24 amino acid ) of the human heat shock protein 60. Diapep277 has shown promising results in preclinical and Phase II clinical studies. subsequent clinical immunoreversal trials at time of diagnosis of type 1 diabetes have demonstrated that the effect of DiaPep277 is dose-dependent and disease-stage dependent. The researchers retracted a Phase III trial and thus the future of DiaPep277 remains uncertain.

Discovery Medicine. 2011 Apr;11(59):293-301.

Monoclonal Antibodies

Anti-CD3 therapy Teplizumab and Otelixizumab are non-Fc receptor binding CD3‑specific humanized monoclonal antibodies (mAbs) that act in a biphasic manner. The Phase III AbATE study (2013) showed a significant preservation in C-peptide for up to 2 years. (patients treated with Teplizumab had a 75% reduced decline in C-peptide at 2 years). There appears to be a distinct risk/benefit profile for anti-CD3 therapeutics with greater doses providing a longer slowing of the autoimmune attack for up to 4 years but at the price of more severe side effects.(Mononucleosis-like syndrome characterized by sore throat, fever and cervical adenopathy, as well as symptoms of cytokine-release syndrome)

Mechanism of Anti-CD3 Therapy

Rituximab Is an Anti-CD20 monoclonal antibody that is able to deplete B cells. Patients treated with this Ab, had better & significant mean C peptide The rituximab group had lower HbA1c However At 2 years, HbA1c and insulin dosage were no longer different in the rituximab than the placebo group.

Canakinumab & Anakirina IL-1 is a pro-inflammatory cytokine that can to cause β-cell dysfunction and destruction via the NFkB and MAPK pathways IL-1 is released locally by the β cells during hyperglycemia, then inhibits insulin synthesis and release and causes apoptosis of β cells. Canakinumab is a human monoclonal anti-IL-1 antibody. In a Phase II clinical trial, canakinumab was administered to patients who had been diagnosed with T1DM. They received subcutaneous injections of 2 mg for 12 months. C-peptide, was not significantly different between the canakinumab and placebo groups. (2013) Anakinra, an IL-1R antagonist, was separately tested in T1DM patients, and similarly resulted in no significant change in data. (2013)

Fusion Proteins Abatacept Abatacept (CTLA4-Ig) is an innovative fusion protein created to supress T cells co-stimulatory signal through the CD28-CD80/86 pathway. In a Phase II trial (2011) , patients received abatacept or placebo for 2 years. At 2 years, the abatacept-treated group had a mean C-peptide about 59% increase and they had a lower adjusted mean HbA1c than the placebo group. Abatacept therapy was well tolerated with clinically insignificant rates of adverse effects, no increase in infection (including EBV), and no increase in neutropenia were observed. The primary concern of abatacept therapy appears to be a return to the inexorable decline in β-cell production after treatment. Similar to the effects of anti-CD3, anti-CD20 and GAD65 vaccine, abatacept therapy seems to slow the autoimmune attack as indicated by reducing the decline in C-peptide.

Treg Cell Therapy In 2014 Study of Treg therapy in newly onset T1D children and is determined that disease duration and initial C-peptide serum level might determine Treg immunotherapy success. In 2015 Study of Treg therapy in adults diagnosed and the result of study was: It reveals that very large numbers of functionally competent, stable, therapeutic-grade Tregs can be obtained by ex vivo expansion. The therapy is well tolerated by the patients with minimal side effects. Together, polyclonal Treg therapy appears to be useful for newly onset T1D in children. However, for adult T1D, it might require further adjustments.

Treg Therapy

Conclusion Antigen-specific therapies and monoclonal antibodies therapies have demonstrated varying yet promising effectiveness in slowing the progression of T1DM in NOD mice studies and, in some cases, human trials. Monoclonal antibodies, such as Teplizumab and Otelixizumab, show promise as immunosuppressants for T1DM by demonstrating improved C-peptide preservation in human trials. Antigen-specific therapies, including the administration of GAD65, HSP60 and insulin peptides, have shown some success in immunomodulation in animal models, but have yet to reveal the same positive, durable effects in human studies.

References 1- Ian C Davis, Jacqueline Randell & Stephen N Davis, Immunotherapies currently indevelopment for the treatment of type 1 diabetes, Expert Opin. Investig. Drugs (2015) 24(10):1331-1341. 2- Jagadeesh Bayryand Jean-Franc¸ ois Gautier, Regulatory T Cell Immunotherapy for Type 1 Diabetes: A Step Closer to Success? Cell Metabolism 23, February 9, 2016 ª2016 Elsevier Inc. 3- Immunotherapy of Type 1 Diabetes: Where Are We and Where Should We Be Going? Xunrong Luo, Kevan C. Herold, and Stephen D. Miller, Immunity 32, April 23, 2010 2010 Elsevier Inc. 4- Paolo Pozzilli, Ernesto Maddaloni and Raffaella Buzzetti, Combination immunotherapies for type 1 diabetes mellitus, Nature reviews endocrinology, advance online publication. 5- James E. Tooley, Frank Waldron-Lynch and Kevan C. Herold, New and future immunomodulatory therapy in type 1 diabetes, Trends in Molecular Medicine, March 2012, Vol. 18, No. 3 6- Frank Waldron-Lynch and Kevan C. Herold. Immunomodulatory therapy to preserve pancreatic β-cell function in type 1 diabetes. Nature reviews . 2011

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