Metabolic shift underlies tumor progression and immune evasion in S-nitrosoglutathione reductase-deficient cancer

S-nitrosoglutathione reductase (GSNOR) is a denitrosylase enzyme that has been suggested to play a tumor suppressor role, although the mechanisms responsible are still largely unclear. In this study, we show that GSNOR deficiency in tumors is associated with poor prognostic histopathological features and poor survival in patients with colorectal cancer (CRC). GSNOR-low tumors were characterized by an immunosuppressive microenvironment with exclusion of cytotoxic CD8⁺ T cells. Notably, GSNOR-low tumors exhibited an immune evasive proteomic signature along with an altered energy metabolism characterized by impaired oxidative phosphorylation (OXPHOS) and energetic dependence on glycolytic activity. CRISPR-Cas9-mediated generation of GSNOR gene knockout (KO) CRC cells confirmed in vitro and in vivo that GSNOR-deficiency conferred higher tumorigenic and tumor-initiating capacities. Moreover, GSNOR-KO cells possessed enhanced immune evasive properties and resistance to immunotherapy, as revealed following xenografting them into humanized mouse models. Importantly, GSNOR-KO cells were characterized by a metabolic shift from OXPHOS to glycolysis to produce energy, as indicated by increased lactate secretion, higher sensitivity to 2-deoxyglucose (2DG), and a fragmented mitochondrial network. Real-time metabolic analysis revealed that GSNOR-KO cells operated close to their maximal glycolytic rate, as a compensation for lower OXPHOS levels, explaining their higher sensitivity to 2DG. Remarkably, this higher susceptibility to glycolysis inhibition with 2DG was validated in patient-derived xenografts and organoids from clinical GSNOR-low tumors. In conclusion, our data support the idea that metabolic reprogramming induced by GSNOR deficiency is an important mechanism for tumor progression and immune evasion in CRC and that the metabolic vulnerabilities associated with the deficiency of this denitrosylase can be exploited therapeutically. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

High-resolution characterization of allelic and haplotypic HLA frequency distribution in a Spanish population using high-throughput next-generation sequencing

Next-generation sequencing (NGS) at the HLA-A, -B, -C, -DPA1, -DPB1, -DQA1, -DQB1, -DRB1 and -DRB3/4/5 loci was performed on 282 healthy unrelated individuals from different major regions of Spain. High-resolution HLA genotypes defined by full sequencing of class I loci and extended coverage of class II loci were obtained to determine allele frequencies and also to estimate extended haplotype frequencies. HLA alleles were typed at the highest resolution level (4-field level, 4FL); with exception of a minor deviation in HLA-DPA1, no statistically significant deviations from expected Hardy Weinberg Equilibrium (HWE) proportions were observed for all other HLA loci. This study provides new 4FL-allele and -haplotype frequencies estimated for the first time in the Spanish population. Furthermore, our results describe extended haplotypes (including the less frequently typed HLA-DPA1 and HLA-DQA1 loci) and show distinctive haplotype associations found at 4FL-allele definition in this Spanish population study. The distinctive allelic and haplotypic diversity found at the 4FL reveals the high level of heterozygosity and specific haplotypic associations displayed that were not apparent at 2-field level (2FL). Overall, these results may contribute as a useful reference source for future population studies, for HLA-disease association studies as a healthy control group dataset and for improving donor recruitment strategies of bone marrow registries. HLA genotyping data of this Spanish population cohort was also included in the 17th International Histocompatibility and Immunogenetics Workshop (IHIW) as part of the study of HLA diversity in unrelated worldwide populations using NGS.

Report from the Killer-cell Immunoglobulin-like Receptors (KIR) component of the 17th International HLA and Immunogenetics Workshop

The goals of the KIR component of the 17th International HLA and Immunogenetics Workshop (IHIW) were to encourage and educate researchers to begin analyzing KIR at allelic resolution, and to survey the nature and extent of KIR allelic diversity across human populations. To represent worldwide diversity, we analyzed 1269 individuals from ten populations, focusing on the most polymorphic KIR genes, which express receptors having three immunoglobulin (Ig)-like domains (KIR3DL1/S1, KIR3DL2 and KIR3DL3). We identified 13 novel alleles of KIR3DL1/S1, 13 of KIR3DL2 and 18 of KIR3DL3. Previously identified alleles, corresponding to 33 alleles of KIR3DL1/S1, 38 of KIR3DL2, and 43 of KIR3DL3, represented over 90% of the observed allele frequencies for these genes. In total we observed 37 KIR3DL1/S1 allotypes, 40 for KIR3DL2 and 44 for KIR3DL3. As KIR allotype diversity can affect NK cell function, this demonstrates potential for high functional diversity worldwide. Allelic variation further diversifies KIR haplotypes. We determined KIR3DL3 ∼ KIR3DL1/S1 ∼ KIR3DL2 haplotypes from five of the studied populations, and observed multiple population-specific haplotypes in each. This included 234 distinct haplotypes in European Americans, 191 in Ugandans, 35 in Papuans, 95 in Egyptians and 86 in Spanish populations. For another 35 populations, encompassing 642,105 individuals we focused on KIR3DL2 and identified another 375 novel alleles, with approximately half of them observed in more than one individual. The KIR allelic level data gathered from this project represents the most comprehensive summary of global KIR allelic diversity to date, and continued analysis will improve understanding of KIR allelic polymorphism in global populations. Further, the wealth of new data gathered in the course of this workshop component highlights the value of collaborative, community-based efforts in immunogenetics research, exemplified by the IHIW.

Report From the First and Second Spanish Killer Immunoglobulin-Like Receptor Genotyping Workshops: External Quality Control for Natural Killer Alloreactive Donor Selection in Haploidentical Stem Cell Transplantation

An important factor affecting the success in the setting of related haploidentical hematopoietic stem cell transplantation (HSCT) is the graft-versus-leukemia effect mediated by natural killer (NK) cells when the donor displays NK alloreactivity versus the recipient. NK cell function is regulated by killer immunoglobulin-like receptors (KIR) and it has been described that donor KIR genotype influences transplantation outcome. This has led to a requirement of laboratories to have a quality assurance program for validation and control of their KIR genotyping methods. The goal of the 1st and 2nd Spanish KIR Genotyping Workshops was to provide an external proficiency testing program in KIR genotyping for Spanish immunology and transplant laboratories. These workshops were conducted during the years 2014-2016 and consisted of 17 participating laboratories typing a set of 20 samples. The presence/absence of 16 mandatory KIR loci (2DL1, 2DL2, 2DL3, 2DL4, 2DL5, 2DS1, 2DS2, 2DS3, 2DS4, 2DS5, 2DP1, 3DL1, 3DL2, 3DL3, 3DS1, and 3DP1) was evaluated per sample. Methods for KIR genotyping included polymerase chain reaction with the use of sequence-specific primers and sequence-specific oligoprobes. Consensus typing was reached in all samples, and the performance of laboratories in external proficiency testing was satisfactory in all cases. The polymorphism detected in the small sample studied in both workshops is indicative of an ample variety of KIR gene profiles in the Spanish population.

[IGF-I, VEGF and bFGF as predictive factors for the onset of retinopathy of prematurity (ROP)]

OBJECTIVE

To determine if IGF-I, VEGF and bFGF, present in the serum of premature infants, are independent risk factors of the development of ROP. It was also our objective to design a multivariate model that included these three cytokines as indicator parameters in the ROP screening, in addition to the other parameters already in existence.

METHODS

74 patients were recruited with a birth weight below 1500g or gestational age below 32 weeks. These were classified into those who developed ROP (N = 37) and those without ROP (N = 37). We obtained serum from each infant at the time of the first examination at 4-6 postnatal weeks. These samples were frozen until the time of analysis. The roles of gestational age and birth weight were also evaluated.

RESULTS

There were significant differences in the amount of the cytokines IGF-I and VEGF between the groups with or without ROP, but there were no significant differences for bFGF. The differences enabled us to establish a multivariate model including IGF-I and VEGF for the prediction of risk of ROP.

CONCLUSIONS

Cytokine serum levels in premature infants can be useful as an indicator in ROP screening, as well as being used to predict the probability of suffering the illness.

Expression of glutaredoxin (thioltransferase) in the rat ovary during the oestrous cycle and postnatal development

Glutaredoxins (Grxs) are low-molecular-weight proteins which participate in redox events in association with glutathione (GSH) and are involved in a variety of cellular processes. It is known that oxidative stress plays important physiological roles within the ovary. In the present study, we have prepared specific antibodies against rat Grx and have used them to localize the protein in the ovaries of rats during postnatal development and during the oestrous cycle, by immunohistochemical methods. We have also performed a quantitative analysis of Grx by ELISA and Western blotting in homogenates of whole ovaries of cycling and pseudopregnant rats. We have found a prominent presence of Grx in the oocytes and in corpora lutea (CL) during developmental and oestrous cycle changes. Grx was absent from the oocytes in the first days of postnatal life when marked oocyte degeneration takes place, but its presence was very conspicuous in the cytoplasm of oocytes in healthy and attretic follicles in rats from 10 days of age onward, independently of the day of oestrous cycle. Follicular cells were negative. Grx immunostaining in the CL was strong in infiltrating macrophages and in a population of steroidogenic cells that survived the apoptotic burst in regressing CL and in CL remnants, but was faint or absent in young CL of the current cycle and in CL during pseudopregnancy. Grx content and oxidoreductase activity in whole ovaries increased significantly during the phase transition from proestrous to oestrous along the cycle. These results support a role of Grx in the maintenance of functional oocytes and in luteal cells surviving the regression process, probably as a consequence of the demonstrated deglutathionylating function of this protein in an antioxidant and antiapoptotic context.