Up-regulation of lysozyme production in colonic adenomas and adenocarcinomas

Single-cell Transcriptomics Reveals Early Molecular and Immune Alterations Underlying the Serrated Neoplasia Pathway Toward Colorectal Cancer

BACKGROUND & AIMS

Approximately one-third of colorectal cancers develop from serrated lesions (SLs), including hyperplastic polyp (HP), sessile serrated lesion (SSL), traditional serrated adenoma (TSA), and SSL with dysplasia (SSLD) through the serrated neoplasia pathway, which progresses faster than the conventional adenoma-carcinoma pathway. We sought to depict the currently unclarified molecular and immune alterations by the single-cell landscape in SLs.

METHODS

We performed single-cell RNA sequencing of 16 SLs (including 4 proximal HPs, 5 SSLs, 2 SSLDs, and 5 TSAs) vs 3 normal colonic tissues.

RESULTS

A total of 60,568 high-quality cells were obtained. Two distinct epithelial clusters with redox imbalance in SLs were observed, along with upregulation of tumor-promoting SerpinB6 that regulated ROS level. Epithelial clusters of SSL and TSA showed distinct molecular features: SSL-specific epithelium manifested overexpressed proliferative markers with Notch pathway activation, whereas TSA-specific epithelium showed Paneth cell metaplasia with aberrant lysozyme expression. As for immune contexture, enhanced cytotoxic activity of CD8⁺ T cells was observed in SLs; it was mainly attributable to increased proportion of CD103⁺CD8⁺ tissue-resident memory T cells, which might be regulated by retinoic acid metabolism. Microenvironment of SLs was generally immune-activated, whereas some immunosuppressive cells (regulatory T cells, anti-inflammatory macrophages, MDK⁺IgA⁺ plasma cells, MMP11-secreting PDGFRA⁺ fibroblasts) also emerged at early stage and further accumulated in SSLD.

CONCLUSION

Epithelial, immune, and stromal components in the serrated pathway undergo fundamental alterations. Future molecular subtypes of SLs and potential immune therapy might be developed.

Clinical Applications of Antimicrobial Peptides (AMPs): Where do we Stand Now?

In this era of multi-drug resistance (MDR), antimicrobial peptides (AMPs) are one of the most promising classes of potential drug candidates to combat communicable as well as noncommunicable diseases such as cancers and diabetes. AMPs show a wide spectrum of biological activities which include antiviral, antifungal, anti-mitogenic, anticancer, and anti-inflammatory properties. Apart from these prospective therapeutic potentials, the AMPs can act as food preservatives and immune modulators. Therefore, AMPs have the potential to replace conventional drugs and may gain a significant global drug market share. Although several AMPs have shown therapeutic potential in vitro or in vivo, in most cases they have failed the clinical trial owing to various issues. In this review, we discuss in brief (i) molecular mechanisms of AMPs in various diseases, (ii) importance of AMPs in pharmaceutical industries, (iii) the challenges in using AMPs as therapeutics and how to overcome, (iv) available AMP therapeutics in market, and (v) AMPs under clinical trials. Here, we specifically focus on the therapeutic AMPs in the areas of dermatology, surgery, oncology and metabolic diseases.

How are the expression patterns of gut antimicrobial peptides modulated by human gastrointestinal diseases? A bridge between infectious, inflammatory, and malignant diseases

The human gut barrier is the tissue exposed to the highest load of microorganisms, harbouring 100 trillion bacteria. In addition, the gut's renewal rate outruns that of any other human tissue. Antimicrobial peptides (AMPs) are highly optimized defense molecules in the intestinal barrier optimized to maintain gastrointestinal homeostasis. Alterations in AMPs activity can lead to or result from human gastrointestinal diseases. In this review, unique, conserved, or otherwise regular alterations in the expression patterns of human AMPs across gastrointestinal inflammatory and infectious diseases were analyzed for pattern elucidation. Human gastrointestinal diseases are associated with alterations in gut AMPs' expression patterns in a peptide-specific, disease-specific, and pathogen-specific way, modulating human gastrointestinal functioning. Across diseases, there is a (i) marked reduction in otherwise constitutively expressed AMPs, leading to increased disease susceptibility, and a (ii) significant increase in the expression of inducible AMPs, leading to tissue damage and disease severity. Infections and inflammatory conditions are associated with altered gene expression in the gut, whose patterns may favour cellular metaplasia, mucosal dysfunction, and disease states. Altered expression of AMPs can thus thrive disease severity and evolution since its early stages. Nevertheless, the modulation of AMP expression patterns unveils promising therapeutic targets.

One-Dimensional Luminous Nanorods Featuring Tunable Persistent Luminescence for Autofluorescence-Free Biosensing

Persistent luminescence nanoparticles (PLNPs), which can remain luminescent after cessation of excitation, have emerged as important materials in biomedicine due to their special ability to eliminate tissue autofluorescence. Even though significant advances have been made in bioimaging, studies on controlled synthesis of PLNPs with tunable properties are lacking. Until now, only a few studies have reported the synthesis of quasi-spherical ZnGa₂O₄:Cr PLNPs, and direct synthesis of PLNPs with other shapes and chemical compositions has not been reported. Herein, we report the direct synthesis of Zn₂GeO₄:Mn (ZGO:Mn) persistent luminescence nanorods (NRs). The length and persistent luminescence of ZGO:Mn NRs can be fine-tuned by simply changing the pH of the hydrothermal reaction system. Moreover, ZGO:Mn NRs exhibit rapid growth rate, and NRs with strong persistent luminescence can be obtained within 30 min of hydrothermal treatment. Aptamer-guided ZGO:Mn bioprobes were further constructed and applied to serum lysozyme analysis. Serum samples from patients with lung cancer, gastric cancer, and colorectal cancer were collected, and the concentrations of lysozyme in these samples were determined. Since the bioprobes displayed long persistent luminescence, serum autofluorescence interference was completely eliminated. The lysozyme quantification results were in good agreement with those obtained using a clinical method, suggesting the good potential of the bioprobes in the analysis of clinical samples. The developed ZGO:Mn NRs possess tunable length and persistent luminescence, and they are ideal for eliminating autofluorescence interference in biosensing, making them valuable in research areas such as studying the functions of biomolecules and monitoring of molecular/cellular networks in their native contexts.

Molecular cloning, sequence analysis and phylogeny of first caudata g-type lysozyme in axolotl (Ambystoma mexicanum)

Lysozymes are key proteins that play important roles in innate immune defense in many animal phyla by breaking down the bacterial cell-walls. In this study, we report the molecular cloning, sequence analysis and phylogeny of the first caudate amphibian g-lysozyme: a full-length spleen cDNA library from axolotl (Ambystoma mexicanum). A goose-type (g-lysozyme) EST was identified and the full-length cDNA was obtained using RACE-PCR. The axolotl g-lysozyme sequence represents an open reading frame for a putative signal peptide and the mature protein composed of 184 amino acids. The calculated molecular mass and the theoretical isoelectric point (pl) of this mature protein are 21523.0 Da and 4.37, respectively. Expression of g-lysozyme mRNA is predominantly found in skin, with lower levels in spleen, liver, muscle, and lung. Phylogenetic analysis revealed that caudate amphibian g-lysozyme had distinct evolution pattern for being juxtaposed with not only anura amphibian, but also with the fish, bird and mammal. Although the first complete cDNA sequence for caudate amphibian g-lysozyme is reported in the present study, clones encoding axolotl's other functional immune molecules in the full-length cDNA library will have to be further sequenced to gain insight into the fundamental aspects of antibacterial mechanisms in caudate.

Molecular characterization, phylogeny, and expression pattern of c-type lysozyme in kelp grouper, Epinephelus bruneus

Lysozymes are the key molecules in innate immune system and possess high bactericidal properties. In the present study, a full-length c-type lysozyme cDNA has been cloned and characterized by expressed sequence tag (EST) and rapid amplification of cDNA ends (RACE) techniques from kelp grouper, Epinephelus bruneus (Eb-CTL). The cDNA consists of 753 base pairs (bp) with a 432 bp open reading frame (ORF) that encodes 144 amino acids (aa) residues and polyadenylation signal sequence AATAAA. The deduced aa sequence polypeptide had a predicted molecular weight of 16 kDa and theoretical isoelectric point of 7.3. The deduced aa sequence have a long lysozyme domain which contains all catalytic sites and other conserved residues required for lysozyme activity. Pair-wise alignments showed a higher identity (76.4%) with Psetta maxima lysozyme and low identity (38.9%) with lysozymes of insect Bombyx mori. Interestingly, phylogenetic analysis revealed that the kelp grouper lysozyme was more closely related to other fish and vertebrate lysozymes. Quantitative real-time reverse transcriptase-PCR analysis showed that Eb-CTL transcripts are constitutively expressed in hematopoietic organs such as heart, spleen, and kidney after stimulation with LPS or infection with Vibrio anguillarum, indicating the involvement of Eb-CTL in the innate immunity of kelp grouper. This study is a first step on the genetics and functions of the c-type lysozyme in kelp grouper, and their role in anti-bacterial activity with reference to immunological properties which might have biotechnological applications.

Molecular characterization, phylogeny, and expression of c-type and g-type lysozymes in brill (Scophthalmus rhombus)

Lysozymes are key proteins of the innate immune system against bacterial infections. In this study we report the molecular cloning and characterization of the c-type and g-type lysozymes in brill (Scophthalmus rhombus). Catalytic and other conserved residues required for functionality were identified. Phylogenetic analysis revealed distinct evolutionary histories for each lysozyme type. Expression profiles of both lysozyme genes were studied in juvenile tissues using a real-time PCR approach. c-Type lysozyme was expressed mainly in stomach and liver, whereas the g-type was detected in all tissues with highest mRNA levels observed in the spleen. Induction experiments revealed that g-type transcripts increased significantly in head kidney after lipopolysaccharide (25- and 23-fold at 12 and 24h, respectively) and Photobacterium damselae subsp. piscicida (17-fold at 24h) treatments. In contrast, no induction was observed for c-type lysozyme. All these data suggest that g-type lysozyme is involved in the response against bacterial infections, whereas c-type lysozyme may also play a role in digestion.

c-Myc overexpression sensitises colon cancer cells to camptothecin-induced apoptosis

The proto-oncogene c-Myc is overexpressed in 70% of colorectal tumours and can modulate proliferation and apoptosis after cytotoxic insult. Using an isogenic cell system, we demonstrate that c-Myc overexpression in colon carcinoma LoVo cells resulted in sensitisation to camptothecin-induced apoptosis, thus identifying c-Myc as a potential marker predicting response of colorectal tumour cells to camptothecin. Both camptothecin exposure and c-Myc overexpression in LoVo cells resulted in elevation of p53 protein levels, suggesting a role of p53 in the c-Myc-imposed sensitisation to the apoptotic effects of camptothecin. This was confirmed by the ability of PFT-α, a specific inhibitor of p53, to attenuate camptothecin-induced apoptosis. p53 can induce the expression of p21^Waf1/Cip1, an antiproliferative protein that can facilitate DNA repair and drug resistance. Importantly, although camptothecin treatment markedly increased p21^Waf1/Cip1 levels in parental LoVo cells, this effect was abrogated in c-Myc-overexpressing derivatives. Targeted inactivation of p21^Waf1/Cip1 in HCT116 colon cancer cells resulted in significantly increased levels of apoptosis following treatment with camptothecin, demonstrating the importance of p21^Waf1/Cip1 in the response to this agent. Finally, cDNA microarray analysis was used to identify genes that are modulated in expression by c-Myc upregulation that could serve as additional markers predicting response to camptothecin. Thirty-four sequences were altered in expression over four-fold in two isogenic c-Myc-overexpressing clones compared to parental LoVo cells. Moreover, the expression of 10 of these genes was confirmed to be significantly correlated with response to camptothecin in a panel of 30 colorectal cancer cell lines.