Can regulatory T cells improve outcomes of sensitised patients after HLA-Ab incompatible renal transplantation: study protocol for the Phase IIa GAMECHANgER-1 trial.

BACKGROUND: Kidney transplantation is the gold-standard treatment for patients with kidney failure. However, one-third of patients awaiting a kidney transplant are highly sensitized to human leukocyte antigens (HLA), resulting in an increased waiting time for a suitable kidney, more acute and chronic rejection, and a shorter graft survival compared to non-highly sensitised patients. Current standard immunosuppression protocols do not adequately suppress memory responses, and so alternative strategies are needed. Autologous polyclonally expanded regulatory T cells (Tregs) have been demonstrated to be safe in transplant settings and could be a potential alternative to modulate memory immune alloresponses. METHODS: The aim of this trial is to determine whether adoptive transfer of autologous Tregs into HLA sensitised patients can suppress memory T and B cell responses against specific HLA antigens. This is a two-part, multi-centre, prospective clinical trial, comprising an observational phase (Part 1) aiming to identify patients with unregulated cellular memory responses to HLA (Pure HLA Proteins) followed by an interventional phase (Part 2). The first 9 patients identified as being eligible in Part 1 will undergo baseline immune monitoring for 2 months to inform statistical analysis of the primary endpoint. Part 2 is an adaptive, open labelled trial based on Simon's two-stage design, with 21 patients receiving Good Manufacturing Practice (GMP)-grade polyclonally expanded Tregs to a dose of 5-10 × 106 cells/kg body weight. The primary EP is suppression of in vitro memory responses for 2 months post-infusion. 12 patients will receive treatment in stage 1 of Part 2, and 9 patients will receive treatment in stage 2 of Part 2 if ≥ 50% patients pass the primary EP in stage 1. DISCUSSION: This is a prospective study aiming to identify patients with unregulated cellular memory responses to Pure HLA Proteins and determine baseline variation in these patterns of response. Part 2 will be an adaptive phase IIa clinical trial with 21 patients receiving a single infusion of GMP-grade polyclonally expanded Tregs in two stages. It remains to be demonstrated that modulating memory alloresponses clinically using Treg therapy is achievable. TRIAL REGISTRATION: EudraCT Number: 2021-001,664-23. REC Number: 21/SC/0253. Trial registration number ISRCTN14582152.

Identification and investigation of mitochondria lacking cytochrome c oxidase activity in axons.

Mitochondrial defects have been implicated in the degeneration of axons in a number of CNS disorders, including multiple sclerosis. Uniquely, mitochondria harbor the only non-nuclear DNA (mitochondrial DNA or mtDNA), which encodes functionally important subunits of the respiratory chain. The pattern of mitochondrial respiratory chain subunit expression provides important clues to the underlying mechanism of mitochondrial injury. In snap frozen tissue mitochondrial respiratory chain complex IV or cytochrome c oxidase (COX) activity may be determined using a well-established histochemical technique, COX histochemistry. Lack of COX activity may be the result of mtDNA mutations, degradation of transcripts of subunits, modification of subunits or inhibition of complexes. Mitochondria lacking complex IV activity, however, have not been further explored within axons in CNS disorders. By combining COX histochemistry with immunofluorescent labeling of mitochondrial proteins we describe a method to identify mitochondria lacking complex IV activity in CNS tissue and locate inactive mitochondria to axons using confocal microscopy. Inactive axonal mitochondria may then be further investigated using confocal microscopy to define the pattern of mitochondrial respiratory chain complex subunit expression. Our technique may be used to gain important clues to the underlying mechanisms of mitochondrial injury within axons in a number of CNS disorders and relevant animal models.

Ten-year-old boy with hemangiopericytoma and human immunodeficiency virus infection.

This report documents the first case of hemangiopericytoma in an HIV-infected child who is most likely a case of vertical transmission of HIV with slow progression to AIDS. We also raise the possibility that there is a causal relationship between HIV and hemangiopericytoma.