Platelet membrane camouflaged AIEgen-mediated photodynamic therapy improves the effectiveness of anti-PD-L1 immunotherapy in large-burden tumors.

Although immunotherapy has achieved recent clinical success in antitumor therapy, it is less effective for solid tumors with large burdens. To overcome this challenge, herein, we report a new strategy based on platelet membrane-camouflaged aggregation-induced emission (AIE) luminogen (Plt-M@P) combined with the anti-programmed death ligand 1 (anti-PD-L1) for tumoral photodynamic-immunotherapy. Plt-M@P is prepared by using poly lactic-co-glycolic acid (PLGA)/PF3-PPh3 complex as a nanocore, and then by co-extrusion with platelet membranes. PF3-PPh3 is an AIE-active conjugated polyelectrolyte with photosensitizing capability for photodynamic therapy (PDT). Plt-M@P exhibits superior tumor targeting capacity in vivo. When applied in small tumor-bearing (~40 mm3) mice, Plt-M@P-mediated PDT significantly inhibits tumor growth. In tumor models with large burdens (~200 mm3), using Plt-M@P-mediated PDT or anti-PD-L1 alone is less effective, but the combination of both is effective in inhibiting tumor growth. Importantly, this combination therapy has good biocompatibility, as demonstrated by the absence of damage to the major organs, especially the reproductive system. In conclusion, we show that Plt-M@P-mediated PDT can improve anti-PD-L1 immunotherapy by enhancing antitumor effects, providing a promising strategy for the treatment of tumors with large burdens.

Subtropical estuarine carbon budget under various hydrologic extremes and implications on the lateral carbon exchange from tidal wetlands.

As coastal areas become more vulnerable to climatic impacts, the need for understanding estuarine carbon budgets with sufficient spatiotemporal resolution arises. Under various hydrologic extremes ranging from drought to hurricane-induced flooding, a mass balance model was constructed for carbon fluxes and their variabilities in four estuaries along the northwestern Gulf of Mexico (nwGOM) coast over a four-year period (2014-2018). Loading of total organic carbon (TOC) and dissolved inorganic carbon (DIC) to estuaries included riverine discharge and lateral exchange from tidal wetlands. The lateral exchanges of TOC and DIC reached 4.5 ± 5.7 and 8.9 ± 1.4 mol·C·m-2·yr-1, accounting for 86.5% and 62.7% of total TOC and DIC inputs into these estuaries, respectively. A relatively high regional CO2 efflux (4.0 ± 0.7 mol·C·m-2·yr-1) was found, which was two times the average value in North American coastal estuaries reported in the literature. Oceanic export was the major pathway for losses of TOC (5.6 ± 1.7 mol·C·m-2·yr-1, 81.2% of total) and DIC (9.9 ± 2.9 mol·C·m-2·yr-1, 69.7% of total). The carbon budget exhibited high variability in response to hydrologic changes. For example, storm or hurricane induced flooding elevated CO2 efflux by 2-10 times in short periods of time. Flood following a drought also increased lateral TOC exchange (from -3.5 ± 4.7 to 67.8 ± 17.6 mmol·C·m-2·d-1) but decreased lateral DIC exchange (from 28.9 ± 3.5 to -7.1 ± 7.6 mmol·C·m-2·d-1). The large variability of carbon budgets highlights the importance of high-resolution spatiotemporal coverage under different hydrologic conditions, and the importance of carbon contribution from tidal wetlands to coastal carbon cycling.

Decadal acidification in a subtropical coastal area under chronic eutrophication.

Coastal acidification is often much more intense than ocean acidification due to eutrophication. To better understand the relationship between long-term coastal acidification (CA) and coastal eutrophication (CE), in-situ monthly data over the past three decades (1986-2017) were analyzed from Hong Kong Coast (HKC). The coastwide annual mean pH change (ΔpHmean) was estimated at -0.0085 ± 0.0069 unit·yr-1 in last decades, which was over four times stronger than current estimation on open ocean acidification rate (∼-0.0019 unit·yr-1). According to the CA spatial pattern, greater pH decline (ΔpHmean = -0.017 ± 0.009 unit·yr-1) occurred in northwest, central south and central east HKC areas, much higher than the less acidified (ΔpHmean = -0.004 ± 0.002 unit·yr-1) southwest and northeast HKC areas. The spatiotemporal CA variations were associated with water discharges, atmospheric CO2 increase and respiration/production that was indicated by DIN:DIP structure changes. The annual mean DIN:DIP ratio increased progressively from initial ∼16 in 1986 to ∼37 in 2017, revealing excess nitrogen load from rapid urbanization in this region. Such discharge-induced acidification was estimated as the major contributor for the total CA in HKC over the last three decades. In addition, our simulation results indicated that a potential CA rate at ∼0.0035 unit·yr-1 could be reached if reducing mean DIN:DIP from discharged water to ∼23 from HKC. This study revealed a previously not recognized relationship between coastal acidification and changing coastal nutrient stoichiometry, and proposed possible management approaches.

Photostable and biocompatible AIE-active conjugated polyelectrolytes for efficient heparin detection and specific lysosome labelling.

A series of new conjugated polyelectrolytes (CPEs) with emissive tetraphenylethene-containing backbones and specific targeting pendants are synthesized and characterized. These new CPEs exhibit prominent aggregation-induced emission (AIE) properties, high photostability and low cytotoxicity, and can efficiently detect heparin and stain lysosomes in living cells.

[Impact of Pseudomonas aeruginosa gene PA1550 on its swimming and twitching motility].

OBJECTIVE: Studying the genes involved in swimming and twitching motility of Pseudomonas aeruginosa. METHODS: We used Mu transposition technique, gene cloning, nucleotide sequencing and the trans-complementation experiment to study the genes involved in twitching motility and swimming motility of P. aeruginosa strain PA68 isolated from a patient with bronchiectasis. RESULTS: A mutant deficient in both swimming and twitching motility was isolated out of about 2000 mini-Mu insertion mutants. The result of GenBank BLAST showed that the mini-Mu transposon had inserted into the gene PA1550 with unknown function. Analyses on the operon of PA550 and the polar effect revealed that Mu transposon had no effect on the transcription of the downstream genes of PA1550. CONCLUSION: PA1550 is involved in the swimming and twitching motility of Pseudomonas aeruginosa.

Identification and functional characterization of pfm, a novel gene involved in swimming motility of Pseudomonas aeruginosa.

Pseudomonas aeruginosa, an important opportunistic pathogen, has a single polar flagellum which is an important virulence and colonization factor by providing swimming motility. This paper describes the functional characterization of a novel gene pfm (PA2950) of P. aeruginosa. The pfm encodes a protein that is similar to a number of short-chain alcohol dehydrogenases of other bacterial species. Mutation of this gene results in a defect in swimming motility which can be completed back to that of wild type by a plasmid containing the pfm. Interestingly, the pfm mutant possesses an intact flagellum which does not rotate, thus giving rise to a non-motile phenotype. The pfm gene is encoded on an operon together with two upstream genes which code for electron transfer flavoprotein (ETF). Yeast two-hybrid tests indicated that the PFM interacts with the ETF, suggesting that the putative dehydrogenase (PFM) is involved in energy metabolism that is critical for the rotation of flagellum in P. aeruginosa.

Identification of a new gene PA5017 involved in flagella-mediated motility, chemotaxis and biofilm formation in Pseudomonas aeruginosa.

Flagella-mediated motility is recognized as one of the major factors contributing to virulence in Pseudomonas aeruginosa. During a screening of a mini-Mu transposon mutant library of P. aeruginosa PA68, a mutant partially deficient in swimming and swarming motility was identified in a new locus that encodes a predicted protein of unknown function annotated PA5017 in the P. aeruginosa PAO1 genome sequence. Chemotaxis plate assay indicated that inactivation of the PA5017 gene led to a decreased chemotactic response. Complementation of the PA5017 mutant with the wild-type PA5017 gene restored normal motility and chemotaxis phenotype. A promoter-lacZ reporter activity assay of the cheYZAB operon from chemotaxis gene cluster 1 showed that there was almost a twofold difference in expression levels of the wild-type PA68 and the PA5017 mutant. This suggested that the PA5017 affected expression of the cheYZAB operon negatively. Further study showed that inactivation of the PA5017 gene in PA68 led to increased biofilm formation in a static system and to the formation of a heterogeneous biofilm in a flow-chamber system. These results suggested that PA5017 possibly affected flagellum-dependent motility and in turn biofilm formation via the chemotaxis signal transduction pathway.

Influence of ptsP gene on pyocyanin production in Pseudomonas aeruginosa.

A pyocyanin overproducer with insertional inactivation of ptsP gene was isolated from a mini-Mu insertion library in Pseudomonas aeruginosa PA68. The mutation was complemented by a functional ptsP gene in trans. The pyocyanin-overproducing phenotype was also found in a ptsP mutant constructed by gene replacement in the P. aeruginosa PAO1 strain. Reporter plasmids with P(qscR)-lacZ, P(lasI)-lacZ and P(rhlI)-lacZ were constructed and the beta-galactosidase activity in the ptsP mutant/wild-type background was measured. The results showed that lack of Enzyme I(Ntr) (EI(Ntr), encoded by ptsP) decreased transcription from the P(qscR) promoter and increased the activity of the P(lasI) and P(rhlI) promoters. Normally, QscR represses the quorum-sensing LasR-LasI and RhlR-RhlI systems involved in pyocyanin regulation. Our results showed that the ptsP gene has an important role in the regulation of pyocyanin production and that two quorum-sensing systems and their repressor QscR are involved in this regulation.

Identification of two new genes involved in twitching motility in Pseudomonas aeruginosa.

Mu transposition complexes were used for transposon mutagenesis of Pseudomonas aeruginosa strain PA68. Mu DNA transposition complexes were assembled with MuA transposase and an artificial mini-Mu transposon in vitro, and introduced into Pseudomonas aeruginosa by electroporation. Eight mutants deficient in twitching motility were isolated. Southern blotting confirmed that the insertions had occurred as single events. DNA sequencing of the region flanking the insertion in the twitching-motility mutants revealed that the mini-Mu transposon had inserted into six different genes, PAO171, PA1822, PAO413, PA4959, PA4551 and PA5040. Four of these have previously been proven to be needed for twitching motility, whereas the PA1822 and PA0171 genes have not previously been shown to be required for twitching motility. The twitching-motility defect in the PA1822 mutant was partially complemented by providing the PA1822 gene in trans, and the defect in the PA0171 mutant was fully complemented when PA0171 was provided. A PA0171 mutant and a PA1822 mutant were constructed by gene replacement in the P. aeruginosa PAO1 strain. These mutants were deficient in twitching motility, showing that both the PA1822 and the PA0171 gene are involved in twitching motility.