A CRISPR activation screen identifies MUC-21 as critical for resistance to NK and T cell-mediated cytotoxicity

BACKGROUND

Immunotherapy has significantly advanced cancer treatments, but many patients do not respond to it, partly due to immunosuppressive mechanisms used by tumor cells. These cells employ immunosuppressive ligands to evade detection and elimination by the immune system. Therefore, the discovery and characterization of novel immunosuppressive ligands that facilitate immune evasion are crucial for developing more potent anti-cancer therapies.

METHODS

We conducted gain-of-function screens using a CRISPRa (CRISPR activation) library that covered the entire human transmembrane sub-genome to identify surface molecules capable of hindering NK-mediated cytotoxicity. The immunosuppressive role and mechanism of MUC21 were validated using NK and T cell mediated cytotoxicity assays. Bioinformatics tools were employed to assess the clinical implications of mucin-21 (MUC21) in cancer cell immunity.

RESULTS

Our genetic screens revealed that MUC21 expression on cancer cell surfaces inhibits both the cytotoxic activity of NK cells and antibody-dependent cellular cytotoxicity, but not affecting complement-dependent cytotoxicity. Additionally, MUC21 expression hinders T cell activation by impeding antigen recognition, thereby diminishing the effectiveness of the immune checkpoint inhibitor, anti-PD-L1. Moreover, MUC21 expression suppress the antitumor function of both CAR-T cells and CAR-NK cells. Mechanistically, MUC21 facilitates immune evasion by creating steric hindrance, preventing interactions between cancer and immune cells. Bioinformatics analysis revealed elevated MUC21 expression in lung cancer, which correlated with reduced infiltration and activation of cytotoxic immune cells. Intriguingly, MUC21 expression was higher in non-small cell lung cancer (NSCLC) tumors that were non-responsive to anti-PD-(L)1 treatment compared to responsive tumors.

CONCLUSIONS

These findings indicate that surface MUC21 serves as a potent immunosuppressive ligand, shielding cancer cells from NK and CD8+T cell attacks. This suggests that inhibiting MUC21 could be a promising strategy to improve cancer immunotherapy.

Short communication: Dietary bovine milk-derived exosomes improve bone health in an osteoporosis-induced mouse model

Osteoporosis is a systemic skeletal disease characterized by low bone mass and micro-architectural deterioration of bone tissue, with a consequent increase in bone fragility and fracture susceptibility. In an aged society with increased life expectancy, the incidence rate of osteoporosis is also rapidly increasing. Inadequate nutrition may negatively influence bone metabolism. Recently, many studies have investigated the functionality of milk-derived exosomes, which play important roles in cell-to-cell communication. However, there are few reports of how milk-derived exosomes influence osteoblast proliferation and differentiation. Here, we determined whether bovine colostrum-derived exosomes promote anti-osteoporosis in vitro and in vivo. Tartrate-resistant acid phosphatase-stained cells were significantly inhibited in Raw264.7 cells treated with exosomes, indicating reduced osteoclast differentiation. We induced osteoporosis in mice using glucocorticoid pellets after orally administering exosomes for 2 mo. Interestingly, the bone mineral density of exosome-fed mouse groups was significantly improved compared with the glucocorticoid-induced osteoporosis group without exosome treatment. In addition, Lactobacillus were decreased in the gut microbiota community of osteoporosis-induced mice, but the gut microbiota community composition was effectively restored by exosome intake. Taken together, we propose that exosomes isolated from bovine colostrum could be a potential candidate for osteoporosis prevention, bone remodeling improvement, and inhibition of bone resorption. To our knowledge, this is the first time that a protective effect of milk exosomes against osteoporosis has been demonstrated in vivo. Our results strongly suggest that bovine colostrum exosomes might be used as a prophylaxis to prevent the onset of osteoporosis. Indeed, our results offer promising alternative strategies in the nutritional management of age-related bone complications.

Expression of sodium/iodide transporters and thyroid stimulating hormone receptors in thyroid cancer patients and its correlation with iodine nutrition status and pathology

OBJECTIVE

To investigate the relationship between the expression of sodium/iodide transporter (NIS) and thyroid stimulating hormone receptor (TSHR) and iodine nutritional status in patients with thyroid carcinoma.

PATIENTS AND METHODS

146 cases of thyroid cancer in Shanghai Gongli Hospital, the Second Military Medical University between February and December 2014 were selected as thyroid cancer group, 120 cases of normal thyroid morphology examined by thyroid ultrasound at the same period were selected as normal group. General information and thyroid function of two groups were recorded and analyzed. H&E staining was used to perform histopathological study on both normal group and thyroid cancer group, and immunohistochemistry was used to detect NIS and TSHR protein expression and position. Reverse transcriptase polymerase chain reaction (RT-PCR) was used for quantitative detection of NIS and TSHR mRNA in the two groups, and the relationship between iodine nutrition and NIS and TSHR expression in thyroid cancer patients was studied. The expression of NIS and TSHR in each group was detected by Western blotting, and the difference in NIS and TSHR expression was analyzed by SPSS 17.0 statistical software.

RESULTS

The difference of serum total triiodothyronine (TT3), total thyroxine (TT4), and thyroid stimulating hormone (TSH) levels between the normal group and the thyroid cancer group was statistically significant (p < 0.05). H&E staining showed that the histopathology of the thyroid cancer group was significantly different from that of the normal group. Immunohistochemistry showed the positive expression of NIS and TSHR in thyroid cancer group. The expression of NIS and TSHR mRNA and protein in thyroid cancer patients was significantly lower than that in normal group detected by RT-PCR and Western blotting. Analysis of variance showed that the difference of NIS and TSHR expression between the two groups was statistically significant (p < 0.05).

CONCLUSIONS

These findings indicated that the expression of NIS and TSHR in thyroid cancer is closely related to iodine nutritional status, which has important research value.

Correction to: Polymyxin B causes DNA damage in HK-2 cells and mice

In the original publication of the article, part of Fig. 6 is missing. The missing subpanels, Fig. 6c, d are given below.

Cellular Assays for Evaluating Calcium-Dependent Translocation of cPLA2α to Membrane

The group IVA phospholipase A₂, commonly called cytosolic phospholipase A₂α (cPLA₂α), is a widely expressed enzyme that hydrolyzes membrane phospholipid to produce arachidonic acid and lysophospholipids, which are precursors for a number of bioactive lipid mediators. Arachidonic acid is metabolized through the cyclooxygenase and lipoxygenase pathways for production of prostaglandins and leukotrienes that regulate normal physiological processes and contribute to disease pathogenesis. cPLA₂α is composed of an N-terminal C2 domain and a C-terminal catalytic domain that contains the Ser-Asp catalytic dyad. The catalytic domain contains phosphorylation sites and basic residues that regulate the catalytic activity of cPLA₂α. In response to cell stimulation, cPLA₂α is rapidly activated by posttranslational mechanisms including increases in intracellular calcium and phosphorylation by mitogen-activated protein kinases. In resting cells, cPLA₂α is localized in the cytosol but translocates to membrane including the Golgi, endoplasmic reticulum, and the peri-nuclear membrane in response to increases in intracellular calcium. Calcium binds to the C2 domain, which promotes the interaction of cPLA₂α with membrane through hydrophobic interactions. In this chapter, we describe assays used to study the calcium-dependent translocation of cPLA₂α to membrane, a regulatory step necessary for access to phospholipid and release of arachidonic acid.

Lactobacillus acidophilus modulates the virulence of Clostridium difficile

Clostridium difficile is a spore-forming, toxin-producing, anaerobic bacterium that colonizes the human gastrointestinal tract. This pathogen causes antibiotic-associated diarrhea and colitis in animals and humans. Antibiotic-associated diseases may be treated with probiotics, and interest is increasing in such uses of probiotics. This study investigated the effect of Lactobacillus strains on the quorum-sensing signals and toxin production of C. difficile. In addition, an in vivo experiment was designed to assess whether Lactobacillus acidophilus GP1B is able to control C. difficile-associated disease. Autoinducer-2 activity was measured for C. difficile using the Vibrio harveyi coupled bioluminescent assay. Cell extract (10μg/mL) of L. acidophilus GP1B exhibited the highest inhibitory activity among 5 to 40μg/mL cell-extract concentrations. Real-time PCR data indicated decreased transcriptional levels in luxS, tcdA, tcdB, and txeR genes in the presence of 10μg/mL of cell extract of L. acidophilus GP1B. Survival rates at 5d for mice given the pathogen alone with L. acidophilus GP1B cell extract or L. acidophilus GP1B were 10, 70, and 80%, respectively. In addition, the lactic acid-produced L. acidophilus GP1B exhibits an inhibitory effect against the growth of C. difficile. Both the L. acidophilus GP1B and GP1B cell extract have significant antipathogenic effects on C. difficile.

Correlation between disc displacements and locations of disc perforation in the temporomandibular joint

OBJECTIVES

The aim of this study was to investigate the correlation between disc displacement types and locations of disc perforation in the temporomandibular joint (TMJ).

METHODS

157 patients (162 joints) with disc perforation observed through arthroscopy were included in this study. The types of disc displacement were analysed by TMJ MRI before operation. The locations of disc perforation under arthroscopy were recorded. The correlation between types of disc displacement and locations of disc perforation was analysed by Fisher's exact test.

RESULTS

Medial disc perforation was observed in 55.6% of patients with anterolateral displacement without reduction, but was observed in only 3.7% of patients with pure anterior displacement, and was not observed in patients with anteromedial displacement without reduction. There was a statistically significant difference between these groups in the incidence of medial disc perforation.

CONCLUSIONS

There is a correlation between different disc displacements and locations of disc perforation. The incidence of medial disc perforation in patients with anterolateral displacement was significantly higher. The types of disc displacement may have direct influence over the locations of disc perforation.

Selective management of obstructive submandibular sialadenitis

We aimed to describe the effect of our surgical and sialoendoscopic technique for diagnosis and treatment of chronic obstructive submandibular sialadenitis.

METHODS

Between January 2004 and June 2006, 68 patients presented with obstructive symptoms and were diagnosed and treated by interventional sialoendoscopy or excision. The patients all had radiographs and then, if the sialolith could not be found, diagnostic sialoendoscopy. The obstruction was treated by operation or interventional sialoendoscopy depending on the size, shape, site, and quality of the sialolith.

RESULTS

Forty-nine patients had sialoliths shown radiographically, and the features of 19 were found endoscopically and were of three types: radiolucent (n=6), in the branch (n=3), mucus plug (n=3), and stenotic (n=7). Twenty-seven obstructions were successfully removed surgically, giving a success rate of 27/31 (87%). Twenty-seven patients were treated by interventional sialoendoscopy, and in 22 cases the sialoliths were removed directly by sialoendoscopy (22/27, 81%). Obstructive symptoms were relieved in 9 of 10 cases without stones.

CONCLUSION

Operation or sialoendoscopy can be used to treat the obstruction in the submandibular gland.

[Pediatric phacoemulsification with Acrysof intraocular lens implantation]

OBJECTIVE

To investigate the operative effects of pediatric phacoemulsification with Acrysof intraocular lens (IOL) implantation.

METHODS

Among 153 eyes of 120 children with cataract aged 3 -- 12 years old, phacoemulsification with Acrysof IOL implantation was performed on 76 eyes of 61 children, and cataract extracapsular extraction with polymethylmethacrylate (PMMA) IOL implantation was performed on 77 eyes of 59 children. The visual acuity, percentages of various complications and rate of neodymium: YAG (Nd: YAG) capsulotomy were followed up for 6 -- 18 months.

RESULTS

There were significant differences in the percentages of various complications and rate of neodymium: YAG (Nd: YAG) capsulotomy between the Acrysof group and the PMMA group (P < 0.01). The Acrysof group was associated with less posterior capsular opacification (6.6%) than the PMMA group (80.5%). The YAG capsulotomy rate was 2.6% for the Acrysof group, and 64.9% for the PMMA group. After operation 100% and 90.6% patients were relieved from blindness in the Acrysof group and the PMMA group respectively, the difference being not statistically significant (P > 0.05). 72.6% patients in the Acrysof group and 51.5% in the PMMA group obtained corrected visual acuity greater-than-or-equal 0.3, and the difference was statistically significant (P < 0.05).

CONCLUSIONS

Phacoemulsification with Acrysof intraocular lens implantation is effective in pediatric cataract surgery. Most of the patients obtain remarkable improvement in visual acuity with minimal complications and YAG capsulotomy rate after operation. It is necessary to perform further randomized and prospective studies to evaluate the long-term postoperative effects of Acrysof IOLs used in pediatric cataract surgery.

The LAMMER protein kinase encoded by the Doa locus of Drosophila is required in both somatic and germline cells and is expressed as both nuclear and cytoplasmic isoforms throughout development

Activity of the Darkener of apricot (Doa) locus of Drosophila melanogaster is required for development of the embryonic nervous system, segmentation, photoreceptor maintenance, normal transcription, and sexual differentiation. The gene encodes a protein kinase, with homologues throughout eukaryotes known as the LAMMER kinases. We show here that DOA is expressed as at least two different protein isoforms of 105 and 55 kD throughout development, which are primarily localized to the cytoplasm and nucleus, respectively. Doa transcripts and protein are expressed in all cell types both during embryogenesis and in imaginal discs. Although it was recently shown that DOA kinase is essential for normal sexual differentiation, levels of both kinase isoforms are equal between the sexes during early pupal development. The presence of the kinase on the cell membrane and in the nuclei of polytene salivary gland cells, as well as exclusion from the nuclei of specific cells, may be indicative of regulated kinase localization. Mosaic analysis in both the soma and germline demonstrates that Doa function is essential for cell viability. Finally, in contrast to results reported in other systems and despite some phenotypic similarities, genetic data demonstrate that the LAMMER kinases do not participate in the ras-MAP kinase signal transduction pathway.

EEG alpha power and alpha power asymmetry in sleep and wakefulness

Asymmetry of waking electroencephalography (EEG) alpha power in frontal regions has been correlated with waking emotional reactivity and the emotional content of dream reports. Little is known regarding alpha asymmetry during sleep. The present study was performed to compare alpha power and alpha power asymmetry in various brain regions across states of sleep and wakefulness. Waking and sleep EEG were recorded in a group of patients undergoing polysomnographic evaluation for possible sleep disorders. Alpha EEG asymmetry in frontal and temporal regions was significantly correlated in waking versus sleep, particularly during rapid eye movement (REM) sleep. These results suggest that patterns of frontal alpha asymmetry are stable across sleep and waking and may be related to emotional reactivity during dreaming. During sleep, alpha power was highest during slow-wave sleep and lowest during REM sleep. Implications of these data for understanding the functional significance of alpha power during waking and sleeping are considered.

The Doa locus encodes a member of a new protein kinase family and is essential for eye and embryonic development in Drosophila melanogaster

Mutations at the Darkener of apricot (Doa) locus of Drosophila cause roughened eyes and increase transcript accumulation from the retrotransposon copia up to fourfold. Cloning of the gene and sequencing of cDNAs reveals that it encodes a putative serine/threonine protein kinase. Sequence data base searches identify it is a member of a novel highly conserved protein kinase family, with homologs in humans, mice, and Saccharomyces cerevisiae, not related to each other previously. Family members are characterized by a peptide motif reading EHLAMMERILG at kinase subdomain X, which is virtually 100% identical in all homologs. We therefore refer to this new family as the LAMMER protein kinases. As predicted from its primary sequence, Doa protein possess intrinsic protein kinase activity when expressed in bacteria, as assayed via autophosphorylation. The gene is expressed throughout development, and both stage and tissue-specific RNAs are found. Its function is essential, because maternally deposited or zygotically transcribed mRNA is required for development to larval stages, and defects in segmentation and development of the nervous system are observed in embryos derived from heteroallelic mothers. Doa function is also critical to Drosophila eye development, because the organization and development of pigment cells, bristles, and photoreceptors are affected in various mutant classes. In the most extreme cases that survive to adulthood, retinal photoreceptors degenerate prior to eclosion. These results demonstrate that the kinase encoded by Doa is required at multiple stages of development, for both differentiation and maintenance of specific cell types.