Gjertrud Skorstad

Stiff person syndrome associated with lower motor neuron disease and infiltration of cytotoxic T cells in the spinal cord

We present a 67-year-old non-diabetic male who presented with muscle cramps, paresis, atrophy and fasciculations in the left leg, followed by rapidly progressive muscle stiffness and superimposed spasms which subsequently also affected the right leg and the trunk. GAD65 autoantibodies were elevated in serum and CSF, compatible with systemic and intrathecal synthesis of oligoclonal and high-avidity autoantibodies, and GAD65 specific T cells were clonally expanded in the CSF. The patient did not respond to GABAergic and immunomodulatory treatment or plasma exchange, and died from respiratory failure after 18 months. Autopsy revealed unilateral axonal swelling, chromatolysis and vacuolisation of anterior horn cells of the lower spinal cord, accompanied by microglia proliferation and discrete infiltration of CD8+ cytotoxic T cells. No CD4+ T helper cells, B cells or complement deposition were detected. To our knowledge, this is the first report of stiff person syndrome with lower motor signs restricted to a lower limb, and also the first attempt to characterize the infiltrating T cells. The finding of CD8+ cytotoxic T cells in the absence of B cells in the inflamed area of the spinal cord suggests that the intrathecal synthesis of GAD65 autoantibodies takes place in areas of the CNS not strictly related to the clinically relevant lesions.

Cerebrospinal fluid T cell responses against glutamic acid decarboxylase 65 in patients with stiff person syndrome

Most patients with stiff person syndrome (SPS) display intrathecal synthesis of oligoclonal and high-avidity IgG against the 65 kDa isoform of glutamic acid decarboxylase (GAD65 IgG), but little is known about the mechanisms driving this immune response. We hypothesized that GAD65-specific T cells accumulating in the central nervous system drive the intrathecal GAD65 IgG production. Accordingly, we were able to clone HLA-DR or DP restricted GAD65-specific T cells from the cerebrospinal fluid (CSF) of all three patients with, but not in one patient without substantial intrathecal production of GAD65 IgG. The CSF T cells recognized four GAD65 epitopes, which were unique to each patient. In two patients, identical or closely related GAD65-specific CSF T cell clones were expanded in vivo. In contrast to the findings in CSF, only one GAD65-specific T cell clone could be raised from the blood of one single patient. Cysteine in amino acid position 474, which is important for enzymatic function of GAD65, was critical for recognition of GAD65(474-484) by HLA-DP restricted CSF T cells. We conclude that GAD65-specific T cells and clonally expanded GAD65-specific B cells coexist intrathecally, where they may collaborate in the synthesis of GAD65 IgG.

GAD65 IgG autoantibodies in stiff person syndrome: clonality, avidity and persistence

Background and purpose:  Persistent intrathecal production of IgG autoantibodies against glutamic acid decarboxylase 65 (GAD65 IgG) and oligoclonal IgG of undetermined specificity has been reported in stiff person syndrome (SPS).

T cells from multiple sclerosis patients recognize multiple epitopes on Self-IgG.

Abstract The highly diversified variable regions of immunoglobulin (Ig) molecules contain immunogenic determinants denoted idiotopes. We have previously reported that T cells from multiple sclerosis (MS) patients recognize IgG from autologous cerebrospinal fluid (CSF), and mapped a T‐cell epitope to an IgG idiotope. To test the ability of CSF IgG molecules to elicit a broad polyclonal T‐cell response in MS, we have analysed T‐cell responses in the blood and CSF against idiotope peptides spanning complementarity determining region (CDR) 3 and somatic mutations within the variable regions of monoclonal CSF IgG. Consistent with a diversified idiotope‐specific T‐cell repertoire, CD4+ T cells from both patients recognized several idiotope peptides presented by HLA‐DR molecules. Mutations were critical for T‐cell recognition, as T cells specific for a mutated CDR1 peptide did not recognize corresponding germline‐encoded peptides. One T‐cell clone recognized both an idiotope peptide and the B‐cell clone expressing this idiotope, compatible with endogenous processing and presentation of this idiotope by B cells. These results suggest that mutated CSF IgG from MS patients carry several T‐cell epitopes, which could mediate intrathecal IgG production and inflammation in MS through idiotope‐driven T–B‐cell collaboration.

MS and clinically isolated syndromes: Shared specificity but diverging clonal patterns of virus-specific IgG antibodies produced in vivo and by CSF B cells in vitro

Background:  Intrathecal synthesis of oligoclonal IgG antibodies against measles virus (MeV), varicella zoster virus (VZV) and herpes simplex virus type‐1 (HSV‐1) is a characteristic feature multiple sclerosis (MS).

Idiotope-specific CD4(+) T cells induce apoptosis of human oligodendrocytes.

CD4(+) T cells specific for immunologic non-self determinants on self-IgG, idiotopes (Id), can be raised from cerebrospinal fluid (CSF) and blood of patients with multiple sclerosis (MS). To test if Id-specific CD4(+) T cells have the potential to destroy oligodendrocytes (ODCs), we analyzed their ability to induce apoptosis of human ODC cell lines. Id-specific CD4(+) T cells stimulated with either Id-bearing B cells, Id-peptide presented by other antigen presenting cells, or by anti-CD3/anti-CD28 in the absence of accessory cells induced DNA fragmentation and killed ODCs. Killing required contact between the ODCs and the T cells, it did not depend on the cytokine profile of the T cells, it was independent of other cell types, and was inhibited by a general caspase inhibitor and an anti-Fas antibody. Activated CD4(+) T cells specific for glutamic acid decarboxylase 65 also induced apoptosis, showing that killing does not depend on cognate interaction between T cells and target cells but rather on the activation status of the T cells.

A TCR-based Chimeric Antigen Receptor

Effector T cells equipped with engineered antigen receptors specific for cancer targets have proven to be very efficient. Two methods have emerged: the Chimeric Antigen Receptors (CARs) and T-cell Receptor (TCR) redirection. Although very potent, CAR recognition is limited to membrane antigens which represent around 1% of the total proteins expressed, whereas TCRs have the advantage of targeting any peptide resulting from cellular protein degradation. However, TCRs depend on heavy signalling machinery only present in T cells which restricts the type of eligible therapeutic cells. Hence, an introduced therapeutic TCR will compete with the endogenous TCR for the signalling proteins and carries the potential risk of mixed dimer formation giving rise to a new TCR with unpredictable specificity. We have fused a soluble TCR construct to a CAR-signalling tail and named the final product TCR-CAR. We here show that, if expressed, the TCR-CAR conserved the specificity and the functionality of the original TCR. In addition, we demonstrate that TCR-CAR redirection was not restricted to T cells. Indeed, after transduction, the NK cell line NK-92 became TCR positive and reacted against pMHC target. This opens therapeutic avenues combing the killing efficiency of NK cells with the diversified target recognition of TCRs.

Abstract 2235: Clinical results of a Phase I/II trial of adjuvant therapeutic vaccination in high risk resected prostate cancer patients using autologous dendritic cells loaded with mRNA from primary prostate cancer tissue, hTERT and survivin

Prostate cancer patients diagnosed with high Gleason score (≥ 8) and large tumors (≥T2c) are considered high-risk patients and >50% will develop an early biochemical relapse. Presently, there is no curative therapy available for patients with biochemical relapse. Based on these findings we initiated in January 2011 a Phase I/II dendritic cell (DC) vaccine study. Patients included have pathological stage pT2 - pT3b, Gleason score 7b-10, pN0, pN+ or pNx and postoperative PSA Citation Format: Anne Merete Aa. Tryggestad, Karol Axcrona, Iris Bigalke, Else M. Inderberg-Suso, Gjertrud Skorstad, Ulrika Axcrona, Steinar Aamdal, Gustav Gaudernack, Dolores Schendel, Wolfgang Lilleby, Svein Dueland, Gunnar Kvalheim. Clinical results of a Phase I/II trial of adjuvant therapeutic vaccination in high risk resected prostate cancer patients using autologous dendritic cells loaded with mRNA from primary prostate cancer tissue, hTERT and survivin. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2235.

Protective and detrimental immunity: lessons from stiff person syndrome and multiple sclerosis

Background – The immune system may attack the brain and cause inflammatory disorders like multiple sclerosis (MS). On the other hand, the immune system may protect and support neurons. Methods– There are two obstacles to study this paradox in humans. First, the target antigens in many human central nervous system (CNS) disorders are unknown. Second, it is often difficult to separate pathogenic from protective events, as well as primary from secondary phenomena. Idiopathic stiff person syndrome (SPS) circumvents the first obstacle, because most patients secrete antibodies against glutamic acid decarboxylase (GAD) 65. The immune response against glatiramer acetate (GA) may circumvent the second obstacle. Migration of activated T helper cells to the intrathecal compartment could be a common denominator in GA treatment and SPS. Results– We here discuss recent results on T cells in MS and SPS, showing that GAD65‐specific and GA‐reactive lymphocytes in the cerebrospinal fluid are not a simple reflection of those in blood. Conclusion– The rules and mechanisms governing T cell selection and maintenance in the CNS may provide a key to the understanding of protective and detrimental aspects of CNS immunity.

Human c-SRC kinase (CSK) overexpression makes T cells dummy

Adoptive cell therapy with T-cell receptor (TCR)-engineered T cells represents a powerful method to redirect the immune system against tumours. However, although TCR recognition is restricted to a specific peptide–MHC (pMHC) complex, increasing numbers of reports have shown cross-reactivity and off-target effects with severe consequences for the patients. This demands further development of strategies to validate TCR safety prior to clinical use. We reasoned that the desired TCR signalling depends on correct pMHC recognition on the outside and a restricted clustering on the inside of the cell. Since the majority of the adverse events are due to TCR recognition of the wrong target, we tested if blocking the signalling would affect the binding. By over-expressing the c-SRC kinase (CSK), a negative regulator of LCK, in redirected T cells, we showed that peripheral blood T cells inhibited anti-CD3/anti-CD28-induced phosphorylation of ERK, whereas TCR proximal signalling was not affected. Similarly, overexpression of CSK together with a therapeutic TCR prevented pMHC-induced ERK phosphorylation. Downstream effector functions were also almost completely blocked, including pMHC-induced IL-2 release, degranulation and, most importantly, target cell killing. The lack of effector functions contrasted with the unaffected TCR expression, pMHC recognition, and membrane exchange activity (trogocytosis). Therefore, co-expression of CSK with a therapeutic TCR did not compromise target recognition and binding, but rendered T cells incapable of executing their effector functions. Consequently, we named these redirected T cells “dummy T cells” and propose to use them for safety validation of new TCRs prior to therapy.