Abstract 2853: Co-delivery of antigen-encoding mRNA and signal 2/3 mRNAs to PBMCs by Cell Squeeze® technology generates SQZ™ eAPCs that prime CD8+T cells in a humanized mouse model

Antigen-specific CD8+ T cells are critical for mounting an effective immune response against tumors. Generation of antigen-specific T cells require interactions with multiple signals produced by antigen presenting cells (APCs). These signals are comprised of three components: (signal 1) the peptide-MHC complex binding to the T cell receptor, (signal 2) costimulatory molecules on the surface of APCs, and (signal 3) inflammatory cytokines binding to cognate receptors on T cells. To engineer all major cell subsets of human peripheral blood mononuclear cells (PBMCs) to become enhanced APCs (eAPCs), we used Cell Squeeze® technology to deliver multiple mRNAs encoding for non-self-antigens (signal 1), CD86 (signal 2), and/or membrane-bound cytokines (signal 3). The signal 3 molecules, membrane-bound IL-12 (mbIL-12) and membrane-bound IL-2 (mbIL-2), are chimeric proteins designed to increase the localized concentration of the cytokines at the immune synapse and limit off-target effects. Flow cytometry confirmed translation of delivered signal 2/3 mRNAs by all major subsets within PBMCs: T cells, B cells, NK cells, and monocytes. The potency of these SQZ™ eAPCs was assessed in vitro by culturing the eAPCs with antigen-specific T cells for multiple days before measuring the functionality of antigen-specific T cells via intracellular cytokine staining or ELISA. Using this approach, we demonstrate that Cell Squeeze® co-delivery of antigen mRNA and signal 2/3 mRNAs significantly enhances CD8+ T cell responses to a variety of antigens, including CMV pp65, Influenza M1, HPV16 E6, and HPV16 E7. Furthermore, we demonstrate that SQZ™ eAPCs drive significant expansion of antigen-specific CD8+ T cells in a humanized mouse model. Thus, we demonstrate that Cell Squeeze® can deliver multiple mRNAs encoding for signals 1, 2, and 3 to human PBMCs and has the potential to generate enhanced APCs that drive strong CD8+ T cell responses against multiple antigens. The versatility of this approach

has the potential to enable rapid exchange of mRNA to encode for other antigens or T cell activation signals.

Citation Format: Michael F. Maloney, Emrah Ilker Ozay, Katarina Blagovic, Carolyne Smith, Andrea A. Silva, Amber Martin, Sanjana Manja, Madhav Upadhyay, Lindsay J. Moore, Ryan Stagg, Henry Mack, Christine Trumpfheller, Pablo Umana, Armon Sharei, Howard Bernstein, Scott M. Loughhead. Co-delivery of antigen-encoding mRNA and signal 2/3 mRNAs to PBMCs by Cell Squeeze® technology generates SQZ™ eAPCs that prime CD8+T cells in a humanized mouse model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2853.

211 SQZ™ eAPCs generated from PBMCs by delivery of multiple mRNAs encoding for antigens, costimulatory proteins, and engineered cytokines

Background

Antigen-specific CD8+ T cells are critical components of mounting an effective immune response against tumors. Generation of antigen-specific T cells require interactions with multiple signals produced by antigen presenting cells (APCs). These signals are comprised of three components: (signal 1) the peptide-MHC complex binding to the T cell receptor, (signal 2) costimulatory molecules on the surface of APCs, and (signal 3) inflammatory cytokines binding to cognate receptors on T cells.

Methods

To engineer all major cell subsets of human peripheral blood mononuclear cells (PBMCs) to become enhanced APCs (eAPCs), we used Cell Squeeze® technology to deliver multiple mRNA encoding for non-self-antigens (signal 1), CD86 (signal 2), and/or membrane-bound cytokines (signal 3). The signal 3 molecules, membrane-bound IL-12 (mbIL-12) and membrane-bound IL-2 (mbIL-2), are chimeric proteins designed to increase the localized concentration of the cytokines and limit off-target effects. Flow cytometry and western blots were used to confirm the translation of each of the delivered mRNA. The increased capabilities of these enhanced APCs were assessed in vitro by culturing the APCs with antigen-specific T cells for multiple days before measuring the functionality of antigen-specific T cells via intracellular cytokine staining or ELISA.

Results

We demonstrate that Cell Squeeze® processing of PBMCs with mRNA encoding for signals 1, 2, and 3 results in highly effective enhanced APCs in vitro. In a single squeeze process, efficient delivery and translation of up to five mRNA is observed in all major PBMC cell subsets including T cells, B cells, NK cells, and monocytes. Once translated, the chimeric mbIL-2 and mbIL-12 can bind to their cognate receptors and exhibit minimal shedding from the surface. We show that enhanced APCs can present antigenic peptides derived from mRNA encoding for a foreign antigen on MHC complexes in an HLA agnostic manner, which drives antigen-specific T cell responses. The addition of CD86, mbIL-2, and mbIL-12 further enhance the activation and potency of antigen-specific T cells, as measured by an increase in the secretion of inflammatory cytokines upon restimulation (i.e. IFNγ).

Conclusions

Cell squeezing of human PBMCs with mRNA encoding for signals 1, 2, and 3 has the potential to generate enhanced APCs that drive robust CD8+ T cell response against multiple targets across several disease areas. The versatility of the Cell Squeeze® technology potentially enables rapid exchange of mRNA to other antigens or T cell activation signals.

Modulation of mtDNA copy number ameliorates the pathological consequences of a heteroplasmic mtDNA mutation in the mouse

Heteroplasmic mtDNA mutations typically act in a recessive way and cause mitochondrial disease only if present above a certain threshold level. We have experimentally investigated to what extent the absolute levels of wild-type (WT) mtDNA influence disease manifestations by manipulating TFAM levels in mice with a heteroplasmic mtDNA mutation in the tRNA^Ala gene. Increase of total mtDNA levels ameliorated pathology in multiple tissues, although the levels of heteroplasmy remained the same. A reduction in mtDNA levels worsened the phenotype in postmitotic tissues, such as heart, whereas there was an unexpected beneficial effect in rapidly proliferating tissues, such as colon, because of enhanced clonal expansion and selective elimination of mutated mtDNA. The absolute levels of WT mtDNA are thus an important determinant of the pathological manifestations, suggesting that pharmacological or gene therapy approaches to selectively increase mtDNA copy number provide a potential treatment strategy for human mtDNA mutation disease.

Need of The Ministry of Health in Federal Democratic Republic of Nepal

The constitution of Nepal provides appointing a council of ministers both at federal and provincial levels without defining portfolios. There is a political agreement that MOH will be retained at the federal level. This article draws evidences around the world to meet health needs of Nepalese, the role of provincial ministry of health and coordinating structure at district/local level. The constitution emphasises on health and pronounced in 46 articles which provides guidance for the creation of federalized governance levels at federal, provincial and local levels. Retaining ministry of health at federal level without creating devolved structure at province and local levels in health sector will create difficulty in translating the spirit of the constitution and may not be effective in addressing health issues nationally and meeting global achievements like SDGs. It is suggested to establish an elaborate health system accordingly in Nepal to ensure constitutional mandate of health as a basic human right.

Is steel wire closure of sternotomy better than polyester suture closure?

INTRODUCTION

Median sternotomy is the preferred approach for open heart surgeries. The sternotomy incision is predominantly closed with either steel wire or polyester suture. The type of material used is primarily based on the surgeon's choice, and both materials achieve a good result. No prospective clinical study has been undertaken to evaluate differences in the incidence of wound infection and the degree of pain associated with both techniques.

PATIENTS AND METHODS

Our randomized controlled double-blind study included 200 adults undergoing single-valve replacement. The technique of surgery, apart from the material used for sternal closure, was the same in both groups. Postoperatively, patients were analyzed for wound infection and wound pain based on the ASEPSIS score and Numeric Pain Rating Score, respectively.

RESULTS

The polyester suture group had a significantly higher mean ASEPSIS score, indicating a higher incidence of wound infection, and more late wound complications. The polyester suture group also had a significantly higher mean pain score. The steel wire group had significantly higher mediastinal drain output in the first 48 h after surgery.

CONCLUSION

The use of polyester suture for sternal closure in adult patients results in increased wound infection, wound pain, and late wound complications, but lower mediastinal drain output.

Cling wrap, an innovative intervention for temperature maintenance and reduction of insensible water loss in very low-birthweight babies nursed under radiant warmers: a randomized, controlled trial

AIM

The value of polythene film ('cling wrap') to improve thermal control and reduce postnatal weight loss in preterm, very low-birthweight babies was investigated.

METHODS

Consecutively born babies with birthweights between 750 and 1500 g were stratified by birthweight (<1250 g, 1251-1500 g) and randomised either to the cling wrap (CW) or no cling wrap (NCW) group. The baby bassinette of the RW was covered with cling wrap up to the level of the neck in the CW group for the 1st 7 days. The primary outcome variables were the incidence of hypothermia (axillary temperature < or = 36 degrees C) after initial stabilisation during the first 7 days and cumulative weight loss (percentage of birthweight) at 48 hours of age.

RESULTS

Of 51 babies, 26 were randomised to the CW and 25 to the NCW group. None of the babies in the CW group developed hypothermia in the 1st 7 days but 36% in the NCW group (p = 0.001) did. Babies who were hypothermic on admission took less time to reach normal temperature in the CW group. Cumulative weight loss in the 1st 48 hours was 5.0 + 5.6% in the CW group and 8.6 + 7.0% in the NCW group (p = 0.06).

CONCLUSION

Use of CW might be a simple method of maintaining temperature in very low-birthweight babies in developing countries.

Window-type patent ductus arteriosus with acquired rheumatic mitral stenosis

An 18-year-old patient with a window type of patent ductus arteriosus and acquired rheumatic mitral stenosis is reported for its rarity. The pitfalls in the diagnosis and surgical management of this condition are discussed.

Interatrial communication with unusual caval venous anomalies

We report a 3-year-old patient with a rare combination of a sinus venosus interatrial communication, anomalous drainage of the right superior pulmonary vein to the right atrium, persistent left superior caval vein, and interruption of the inferior caval vein. We discuss features of anatomical and technical interest.

Mini-implants for retraction, intrusion and protraction in a Class II division 1 patient

This case report demonstrates the clinical utility and versatility of mini-implants in carrying out different types of tooth movement in a 14-year-old boy with a 'severe' Class II division 1 malocclusion. Mini-implants were placed for 'en masse' retraction and intrusion of maxillary anterior teeth and for lower molar protraction. More than 11 mm of maxillary incisor retraction was achieved together with 3 mm of intrusion. There was significant reduction in the dentoalveolar protrusion and retraction of the upper lip, which resulted in decreased mentalis strain and improved chin projection. Cephalometric superimposition and panoramic radiographs showed no anchorage loss and good occlusion at the end of treatment.

Hypocalcemia in the newborn

Healthy term babies undergo a physiological nadir in serum calcium levels by 24-48 hours of age. This nadir may be related to the delayed response of parathyroid and calcitonin hormones in a newborn. This nadir may drop to hypocalcemic levels in high-risk neonates including infants of diabetic mothers, preterm infants and infants with perinatal asphyxia. This early onset hypocalcemia which presents within 72 hours, requires treatment with calcium supplementation for at least 72 hours. In contrast late onset hypocalcemia usually presents after 7 days and requires long term therapy. Ionized calcium is crucial for many biochemical processes and total serum calcium is a poor substitute for the diagnosis of hypocalcemia.

Zinc uptake, oxidative stress and the FNR-like proteins of Lactococcus lactis

Lactococcus lactis ssp. cremoris MG1363 contains two FNR homologues, FlpA and FlpB, encoded by the distal genes of two paralogous operons (orfX(A/B)-orfY(A/B)-flpA/B). An flpA flpB double mutant strain is hypersensitive to hydrogen peroxide and has a depleted intracellular Zn(II) pool. The phenotypes of the flp mutant strains suggest that FlpA and FlpB control the expression of high and low affinity ATP-dependent Zn(II) uptake systems, respectively. Plate tests revealed that expression from a orfX(B)::lac reporter was activated by Cd(II), consistent with other Zn(II)-regulated systems. The link between a failure to acquire Zn(II) and hypersensitivity to oxidative stress suggests that Zn(II) may be required to protect vulnerable protein thiols from oxidation.