Expanded autologous regulatory T-lymphocyte infusions in ALS: A phase I, first-in-human study

Inflammation in ALS/FTD pathogenesis

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are neurodegenerative diseases that overlap in their clinical presentation, pathology and genetics, and likely represent a spectrum of one underlying disease. In ALS/FTD patients, neuroinflammation characterized by innate immune responses of tissue-resident glial cells is uniformly present on end-stage pathology, and human imaging studies and rodent models support that neuroinflammation begins early in disease pathogenesis. Additionally, changes in circulating immune cell populations and cytokines are found in ALS/FTD patients, and there is evidence for an autoinflammatory state. However, despite the prominent role of neuro- and systemic inflammation in ALS/FTD, and experimental evidence in rodents that altering microglial function can mitigate pathology, therapeutic approaches to decrease inflammation have thus far failed to alter disease course in humans. Here, we review the characteristics of inflammation in ALS/FTD in both the nervous and peripheral immune systems. We further discuss evidence for direct influence on immune cell function by mutations in ALS/FTD genes including C9orf72, TBK1 and OPTN, and how this could lead to the altered innate immune system “tone” observed in these patients.

Neuroinflammatory mechanisms in amyotrophic lateral sclerosis pathogenesis

PURPOSE OF REVIEW

Neuroinflammation is increasingly recognized as an important mediator of disease progression in patients with amyotrophic lateral sclerosis (ALS), and is characterized by reactive central nervous system (CNS) microglia and astroglia as well as infiltrating peripheral monocytes and lymphocytes. Anti-inflammatory and neuroprotective factors sustain the early phase of the disease whereas inflammation becomes proinflammatory and neurotoxic as disease progression accelerates. Initially, motor neurons sustain injuries through multiple mechanisms resulting from harmful mutations causing disruptions of critical intracellular pathways. Injured motor neurons release distress signal(s), which induce inflammatory processes produced by surrounding glial cells in the CNS as well as peripheral innate and adaptive immune cells. This review will focus on mechanisms of neuroinflammation and their essential contributions in ALS pathogenesis.

RECENT FINDINGS

Regulatory T lymphocytes (Tregs) are a subpopulation of immunosuppressive T lymphocytes that become reduced and dysfunctional as the disease progresses in ALS patients. Their degree of dysfunction correlates with the extent and rapidity of the disease. Treg numbers are boosted in transgenic mutant SOD1 (mSOD1) mice through the passive transfer of Tregs or through treatment with an interleukin-2/ interleukin-2 monoclonal antibody complex and rapamycin. Treating the transgenic mice with either of these modalities delays disease progression and prolongs survival. In addition, Treg function is restored when dysfunctional Tregs are isolated from ALS patients and expanded ex vivo in the presence of interleukin-2 and rapamycin. Based on these findings, a first-in-human phase 1 trial has been completed in which expanded autologous Tregs were infused back into ALS patients as a potential treatment. The infusions were safe and shown to 'hit target' by enhancing both Treg numbers and suppressive functions.

SUMMARY

A delicate balance between anti-inflammatory and proinflammatory factors modulates the rates of disease progression and survival times in ALS. Tipping the balance toward the anti-inflammatory mediators shows promise in slowing the progression of this devastating disease.

Methods to manufacture regulatory T cells for cell therapy

Regulatory T cell (T_reg ) therapy has shown promise in early clinical trials for treating graft-versus-host disease, transplant rejection and autoimmune disorders. A challenge has been to isolate sufficiently pure T_regs and expand them to a clinical dose. However, there has been considerable progress in the development and optimization of these methods, resulting in a variety of manufacturing protocols being tested in clinical trials. In this review, we summarize methods that have been used to manufacture T_regs for clinical trials, including the choice of cell source and protocols for cell isolation and expansion. We also discuss alternative culture or genome editing methods for modulating T_reg specificity, function or stability that could be applied to future clinical manufacturing protocols to increase the efficacy of T_reg therapy.

Mesenchymal Stem Cells: A Potential Therapeutic Approach for Amyotrophic Lateral Sclerosis?

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the degeneration of both upper and lower motor neurons. Patients show both motor and extra-motor symptoms. A cure is not available at this time, and the disease leads to death within 3-5 years, mainly due to respiratory failure. Stem cell therapy is arising as a new promising approach for the treatment of neurodegenerative disorders. In particular, mesenchymal stem cells (MSCs) seem the most suitable type of stem cells, thanks to their demonstrated beneficial effects in different experimental models, to the easy availability, and to the lack of ethical problems. In this review, we focused on the studies involving ALS rodent models and clinical trials in order to understand the potential beneficial effects of MSC transplantation. In different ALS rodent models, the administration of MSCs induced a delay in disease progression and at least a partial recovery of the motor function. In addition, clinical trials evidenced the feasibility and safety of MSC transplantation in ALS patients, given that no major adverse events were recorded. However, only partial improvements were shown. For this reason, more studies and trials are needed to clarify the real effectiveness of MSC-based therapy in ALS.

Ways Forward for Tolerance-Inducing Cellular Therapies- an AFACTT Perspective

Clinical studies with cellular therapies using tolerance-inducing cells, such as tolerogenic antigen-presenting cells (tolAPC) and regulatory T cells (Treg) for the prevention of transplant rejection and the treatment of autoimmune diseases have been expanding the last decade. In this perspective, we will summarize the current perspectives of the clinical application of both tolAPC and Treg, and will address future directions and the importance of immunomonitoring in clinical studies that will result in progress in the field.

Reprogrammed CD4+ T Cells That Express FoxP3+ Control Inhibitory Antibody Formation in Hemophilia A Mice

Coagulation Factor VIII (FVIII) replacement therapy in hemophilia A patients is complicated by the development of inhibitory antibodies, which often render the treatment ineffective. Previous studies demonstrated a strong correlation between induction of regulatory T cells (Treg) and tolerance to the therapeutic protein. We, therefore, set out to evaluate whether the adoptive transfer of FVIII-specific CD4⁺ Treg cells prevents inhibitor response to FVIII protein therapy. To this end, we first retrovirally transduced FoxP3⁺ into FVIII-specific CD4⁺ cells, which resulted in cells that stably express FoxP3, are phenotypically similar to peripherally induced Tregs and are antigen specific suppressors, as judged by in vitro assays. Upon transfer of the FVIII-specific CD4⁺ FoxP3⁺ cells into hemophilia A mice, development of inhibitory antibodies in response to administering FVIII protein was completely suppressed. Suppression was extended for 2 months, even after transferred cells were no longer detectable in the secondary lymphoid organs of recipient animals. Upon co-transfer of FoxP3⁺-transduced cells with the B cell depleting anti-CD20 into mice with pre-existing inhibitory antibodies to FVIII, the escalation of inhibitory antibody titers in response to subsequent FVIII protein therapy was dramatically reduced. We conclude that reprogramed FoxP3 expressing cells are capable of inducing the in vivo conversion of endogenous FVIII peripheral Tregs, which results in sustained suppression of FVIII inhibitors caused by replacement therapy in recipient hemophilia A animals.

Safety of intrathecal injection of Wharton's jelly-derived mesenchymal stem cells in amyotrophic lateral sclerosis therapy

Animal experiments have confirmed that mesenchymal stem cells can inhibit motor neuron apoptosis and inflammatory factor expression and increase neurotrophic factor expression. Therefore, mesenchymal stem cells have been shown to exhibit prospects in the treatment of amyotrophic lateral sclerosis. However, the safety of their clinical application needs to be validated. To investigate the safety of intrathecal injection of Wharton's jelly-derived mesenchymal stem cells in amyotrophic lateral sclerosis therapy, 43 patients (16 females and 27 males, mean age of 57.3 years) received an average dose of 0.42 × 10⁶ cells/kg through intrathecal administration at the cervical, thoracic or lumbar region depending on the clinical symptoms. There was a 2 month interval between two injections. The adverse events occurring during a 6-month treatment period were evaluated. No adverse events occurred. Headache occurred in one case only after first injection of stem cells. This suggests that intrathecal injection of Wharton's Jelly-derived mesenchymal stem cells is well tolerated in patients with amyotrophic lateral sclerosis. This study was approved by the Bioethical Committee of School of Medicine, University of Warmia and Mazury in Olsztyn, Poland (approval No. 36/2014 and approval No. 8/2016). This study was registered with the ClinicalTrials.gov (identifier: NCT02881476) on August 29, 2016.

Longitudinal assessment of clinical and inflammatory markers in patients with amyotrophic lateral sclerosis

OBJECTIVE

To evaluate potential associations between clinical features and inflammatory markers in patients with amyotrophic lateral sclerosis (ALS).

METHODS

A consecutive series of 68 patients (39 males and 29 females) with sporadic ALS were subjected to a comprehensive clinical assessment and blood draw. A subset of these patients underwent a new assessment within 6-12 months after the baseline visit. In addition, a group of 62 subjects composed by age and sex-matched healthy subjects (38 males and 24 females) was enrolled in this study. Peripheral blood was drawn and plasma levels of chemokines and cytokines were measured by cytometric bead array and enzyme-linked immunosorbent assay.

RESULTS

Our sample was composed by patients with ALS with an average age of 58 (±12.3) years old and 3 (±2.7) years of disease length at the baseline visit. Patients with ALS presented increased plasma levels of interleukin (IL)-6 and IL-8 in comparison with controls. After multivariate analysis, higher levels of IL-6 and lower levels of IL-2 were significantly associated with increased likelihood of ALS diagnosis. When evaluating the subset of patients assessed longitudinally, we did not find any significant difference in the levels of inflammatory markers between the two time points. Older age at ALS onset was the only factor associated with a faster rate of disease progression.

CONCLUSIONS

IL-6 levels could discriminate between ALS and controls and may be regarded as a potential biomarker of ALS diagnosis. An increase in IL-2 levels was associated with a protective effect on the odds of ALS diagnosis. Older age at ALS onset predicted a fast rate of disease progression.