An Atlas of Grass Carp IgM+ B Cells in Homeostasis and Bacterial Infection Helps to Reveal the Unique Heterogeneity of B Cells in Early Vertebrates.

Teleost B cells are primitive lymphocytes with both innate and adaptive immune functions. However, the heterogeneity and differentiation trajectory of teleost B cells remain largely unknown. In this study, the landscape of grass carp IgM+ (gcIgM+) B cells was revealed by single-cell RNA sequencing. The results showed that gcIgM+ B cells mainly comprise six populations: (im)mature B cells, innate B cells, proliferating B cells, plasma cells, CD22+ cells, and CD34+ cells, among which innate B cells and proliferating B cells were uncommon B cell subsets with, to our knowledge, new characteristics. Remarkably, three functional IgMs were discovered in grass carp, and a significant percentage of gcIgM+ B cells, especially plasma cells, expressed multiple Igµ genes (Igµ1, Igµ2, and/or Igµ3). More importantly, through single-cell sorting combined with Sanger sequencing, we found that distinct VHDJH recombination patterns of Igµ genes were present in single IgM+ B cells, indicating that individual teleost B cells might produce multiple Abs by coexpressing rearranged IgM subclass genes. Moreover, the percentage of IgM1highIgM2highIgM3high plasma cells increased significantly after bacterial infection, suggesting that individual plasma cells might tend to produce multiple IgMs to resist the infection in teleost fish. In summary, to our knowledge, this study not only helps to uncover the unique heterogeneity of B cells in early vertebrates but also provided significant new evidence supporting the recently proposed "one cell-multiple Abs" paradigm, challenging the classical rule of "one cell-one Ab."

Insights into the Antibacterial Properties of Complement Peptides C3a, C4a, and C5a across Vertebrates.

Complement peptides C3a, C4a, and C5a are important components of innate immunity in vertebrates. Although they diverged from a common ancestor, only C3a and C4a can act as antibacterial peptides in Homo sapiens, suggesting that C5a has evolved into a purely chemotactic molecule; however, the antibacterial properties of C3a, C4a, and C5a across vertebrates still require elucidation. In this article, we show that, unlike those in H. sapiens, Mus musculus C3a, C4a, and C5a all possess antibacterial activities, implying that the antibacterial properties of C3a, C4a, and C5a have evolved divergently in vertebrates. The extremely different net charge, a key factor determining the antibacterial activities of cationic antimicrobial peptides, of vertebrate C3a, C4a, and C5a supports this speculation. Moreover, the antibacterial activity of overlapping peptides covering vertebrate C3a, C4a, and C5a further strongly supports the speculation, because their activity is positively correlated with the net charge of source molecules. Notably, the structures of C3a, C4a, and C5a are conserved in vertebrates, and the inactive overlapping peptides can become antibacterial peptides if mutated to possess enough net positive charges, indicating that net charge is the only factor determining the antibacterial properties of vertebrate C3a, C4a, and C5a. More importantly, many vertebrate C3a-, C4a-, and C5a-derived peptides possess high antibacterial activities yet exhibit no hemolytic activities, suggesting the application potential in anti-infective therapy. Taken together, our findings reveal that vertebrate C3a, C4a, and C5a are all sources of antibacterial peptides that will facilitate the design of excellent peptide antibiotics.

Insights into the Antibacterial Properties of Complement Peptides C3a, C4a, and C5a across Vertebrates.

Complement peptides C3a, C4a, and C5a are important components of innate immunity in vertebrates. Although they diverged from a common ancestor, only C3a and C4a can act as antibacterial peptides in Homo sapiens, suggesting that C5a has evolved into a purely chemotactic molecule; however, the antibacterial properties of C3a, C4a, and C5a across vertebrates still require elucidation. In this article, we show that, unlike those in H. sapiens, Mus musculus C3a, C4a, and C5a all possess antibacterial activities, implying that the antibacterial properties of C3a, C4a, and C5a have evolved divergently in vertebrates. The extremely different net charge, a key factor determining the antibacterial activities of cationic antimicrobial peptides, of vertebrate C3a, C4a, and C5a supports this speculation. Moreover, the antibacterial activity of overlapping peptides covering vertebrate C3a, C4a, and C5a further strongly supports the speculation, because their activity is positively correlated with the net charge of source molecules. Notably, the structures of C3a, C4a, and C5a are conserved in vertebrates, and the inactive overlapping peptides can become antibacterial peptides if mutated to possess enough net positive charges, indicating that net charge is the only factor determining the antibacterial properties of vertebrate C3a, C4a, and C5a. More importantly, many vertebrate C3a-, C4a-, and C5a-derived peptides possess high antibacterial activities yet exhibit no hemolytic activities, suggesting the application potential in anti-infective therapy. Taken together, our findings reveal that vertebrate C3a, C4a, and C5a are all sources of antibacterial peptides that will facilitate the design of excellent peptide antibiotics.

LncRNA GAS5 activates the HIF1A/VEGF pathway by binding to TAF15 to promote wound healing in diabetic foot ulcers.

A diabetic foot ulcer (DFU) is one of the most devastating complications of diabetes. It has been reported that lncRNA GAS5 plays a vital role in wound healing in DFUs. However, the specific mechanism remains unclear. In this research, we aimed to investigate the role of GAS5 in wound healing in DFUs as well as the underlying mechanism. qPCR or western blotting was performed to measure the expression levels of GAS5, HIF1A, VEGF and TAF15. CCK-8 or EdU assays, flow cytometry, wound healing assays and tube formation assays were carried out to assess the proliferation, apoptosis, wound healing and in vitro angiogenesis of HUVECs, respectively. RNA pull-down and RIP assays were performed to verify the interaction between GAS5 and TAF15. ChIP and luciferase assays were conducted to verify the binding of TAF15 to the HIF1A promoter. In the DFU mouse model, H&E and Masson staining were used to determine epidermal and dermal thickness and collagen formation. GAS5 and HIF1A were downregulated in the skin tissues of DFU patients, and GAS5 overexpression promoted cell proliferation, wound healing and tubule formation in HG-treated HUVECs. In addition, GAS5 facilitated HIF1A expression by interacting with TAF15. Rescue assays demonstrated that the suppression of HIF1A/VEGF pathway activation partially reversed the functional roles of GAS5 in HUVECs. Furthermore, GAS5 accelerated wound healing by activating the HIF1A/VEGF pathway in mice with DFUs. GAS5 activates the HIF1A/VEGF pathway by binding to TAF15, resulting in accelerated wound healing in DFUs. Our findings may provide a theoretical basis for the clinical treatment of DFUs.

Deficit of long-term memory traces for words in children with cochlear implants.

OBJECTIVE: Language experience can develop long-term memory traces for speech units in the brain, to ensure efficient processing of speech sounds. However, prelingually deafened children lack sufficient auditory input before cochlear implantation. Whether the experience-dependent long-term memory traces exist in prelingually deafened children with cochlear implants (CIs) remains unclear. METHODS: We presented CI and normal hearing (NH) children with Mandarin Chinese spoken disyllables in an oddball paradigm and recorded event-related potentials. Each disyllable was defined as a meaningful word or a meaningless pseudoword by the tonal information in the second syllable. RESULTS: The amplitude of mismatch negativity (MMN) elicited by words was larger than that elicited by pseudowords in NH children. However, this enhancement of the MMN amplitude was not found in CI children. Behavioral results showed later recognition points for words and lower accuracies for speech comprehension in CI children than in NH children. Furthermore, increased theta power for words compared with pseudowords was only found in NH children. CONCLUSIONS: Our findings indicate a deficit of long-term memory traces for words in prelingually deafened children with cochlear implants. SIGNIFICANCE: Early speech input may be crucial to the formation of long-term memory traces for speech units.

[High-risk behaviors related to AIDS/STDs infections among fishermen in Lü-si harbor, Jiangsu province].

OBJECTIVE: To investigate the high-risk behaviors related to acquired immune deficiency syndrome/sexually transmitted disease (AIDS/STDs) infection among fishermen in Lü-si harbor, Jiangsu province. METHODS: A cross-sectional study was designed to investigate the research participants' demographic characteristics, high-risk behaviors that related to AIDS/STDs. Logistic regression was performed to measure the associations between potential risk factors and reported potential high-risk sexual behavior. RESULTS: 817 fishermen participated in the study and casual or commercial sex activities appeared to be the main high-risk behavior for AIDS/STDs infection in the target population. The rates of casual and commercial sex reported were 18.1% and 28.9% among fishermen. Risk factors associated with AIDS/STDs related high-risk behaviors among fishermen were high mobility (OR = 1.516, P = 0.038), higher lifetime sex frequency (OR = 1.422, P = 0.002) and unmarried status (OR = 7.527, P = 0.014). Protective factors against high-risk behaviors were low intake of alcohol (OR = 0.803, P = 0.053), negative STD history (OR = 0.268, P = 0.001), age of initial sexual intercourse at or older than 22 years (OR = 0.440, P = 0.000) of age, as well as negative attitude toward multiple sexual partners (OR = 0.662, P = 0.023) and legitimation for commercial sex (OR = 0.612, P = 0.007). CONCLUSION: There were risk behaviors of AIDS/STDs in those infected fishmen. Casual and commercial sex were common high-risk behaviors.