Molecular mechanism of siderophore regulation by the Pseudomonas aeruginosa BfmRS two-component system in response to osmotic stress.

Pseudomonas aeruginosa, a common nosocomial pathogen, relies on siderophores to acquire iron, crucial for its survival in various environments and during host infections. However, understanding the molecular mechanisms of siderophore regulation remains incomplete. In this study, we found that the BfmRS two-component system, previously associated with biofilm formation and quorum sensing, is essential for siderophore regulation under high osmolality stress. Activated BfmR directly bound to the promoter regions of pvd, fpv, and femARI gene clusters, thereby activating their transcription and promoting siderophore production. Subsequent proteomic and phenotypic analyses confirmed that deletion of BfmRS reduces siderophore-related proteins and impairs bacterial survival in iron-deficient conditions. Furthermore, phylogenetic analysis demonstrated the high conservation of the BfmRS system across Pseudomonas species, functional evidences also indicated that BfmR homologues from Pseudomonas putida KT2440 and Pseudomonas sp. MRSN12121 could bind to the promoter regions of key siderophore genes and osmolality-mediated increases in siderophore production were observed. This work illuminates a novel signaling pathway for siderophore regulation and enhances our understanding of siderophore-mediated bacterial interactions and community establishment.

[Establishment of Quantitative SPR Assay for Antibodies Against Human Platelet Antigen-1a].

OBJECTIVE: To establish quantitative surface plasmon resonance (SPR) assay for antibodies against human platelet antigen-1a (HPA-1a). METHODS: Recombinant protein was fixed on the chip surface by amino coupling method. SPR assay was used to detect the standard antibodies against HPA-1a at different conceatration. The optimal experimental parameters were determined, and standard curves were constructed with linear regression. Moreover, the sensitivity, specificity, accuracy and precision of the assay were evaluated. RESULTS: The quantitative SPR assay for HPA-1a antibodies was established. The determination ranges were 0-20 IU, with accuracy (recovery rate) was 97.75%-103.08%. The intra-assay precision [coefficients of variation (CV)] was 3.53%-4.29%, and the inter-assay precision (CV) was 2.08%-4.40%. For specificity test, several kinds of monoclonal and human antibodies against platelet membrane protein were tested and no positive result was observed. CONCLUSION: The established quantitative SPR assay for HPA-1a antibodies shows good sensitivity, specificity, accuracy and precision, and this rapid and simple method provides a new reference method for scientific research and clinical antibody detection.

Serum interleukin-33 as a novel marker for long-term prognosis and recurrence in acute ischemic stroke patients.

OBJECTIVES: Interleukin-33, a newly identified member of interleukin-1 family, had been confirmed to play a crucial role in regulating inflammatory responses in various disease. However, the exact role of interleukin-33 in the disease process of acute ischemic stroke still remains unclear. This study aims to demonstrate the relationship between interleukin-33 levels and long-term functional outcome as well as ischemic stroke recurrence. METHODS: Three hundred and four first-ever acute ischemic stroke patients were recruited and basic information and history of all subjects taken within 72 hr on admission. The functional outcome was estimated by Barthel index. The multivariate logistic regression was used to analyze the prognosis, while the Cox proportional hazard model was applied to assess the recurrence risk. RESULTS: Out of 304 subjects, 259 patients successfully completed scheduled two-year follow-up. We found that higher interleukin-33 levels correlated positively with better prognosis as compared with those with lower interleukin-33 levels who presented with poorer outcome (62.45 ± 20.50 ng/ml vs. 51.58 ± 19.16 ng/ml, p < .001). After adjustment of all confounders, interleukin-33 was associated with the one-year prognosis with an adjusted odds ratio of 0.956 (95% confidence interval, 0.937-0.976, p < .001). Furthermore, interleukin-33 levels were also closely related to recurrent ischemic stroke with an adjusted hazard ratio of 0.979 (95% confidence interval, 0.961-0.997, p = .025). CONCLUSIONS: IL-33 can be used to predict the long-term outcomes and ischemic stroke recurrence in first-ever acute ischemic stroke patients.