FOXO1 reshapes neutrophils to aggravate acute brain damage and promote late depression after traumatic brain injury.

BACKGROUND: Neutrophils are traditionally viewed as first responders but have a short onset of action in response to traumatic brain injury (TBI). However, the heterogeneity, multifunctionality, and time-dependent modulation of brain damage and outcome mediated by neutrophils after TBI remain poorly understood. METHODS: Using the combined single-cell transcriptomics, metabolomics, and proteomics analysis from TBI patients and the TBI mouse model, we investigate a novel neutrophil phenotype and its associated effects on TBI outcome by neurological deficit scoring and behavioral tests. We also characterized the underlying mechanisms both in vitro and in vivo through molecular simulations, signaling detections, gene expression regulation assessments [including dual-luciferase reporter and chromatin immunoprecipitation (ChIP) assays], primary cultures or co-cultures of neutrophils and oligodendrocytes, intracellular iron, and lipid hydroperoxide concentration measurements, as well as forkhead box protein O1 (FOXO1) conditional knockout mice. RESULTS: We identified that high expression of the FOXO1 protein was induced in neutrophils after TBI both in TBI patients and the TBI mouse model. Infiltration of these FOXO1high neutrophils in the brain was detected not only in the acute phase but also in the chronic phase post-TBI, aggravating acute brain inflammatory damage and promoting late TBI-induced depression. In the acute stage, FOXO1 upregulated cytoplasmic Versican (VCAN) to interact with the apoptosis regulator B-cell lymphoma-2 (BCL-2)-associated X protein (BAX), suppressing the mitochondrial translocation of BAX, which mediated the antiapoptotic effect companied with enhancing interleukin-6 (IL-6) production of FOXO1high neutrophils. In the chronic stage, the "FOXO1-transferrin receptor (TFRC)" mechanism contributes to FOXO1high neutrophil ferroptosis, disturbing the iron homeostasis of oligodendrocytes and inducing a reduction in myelin basic protein, which contributes to the progression of late depression after TBI. CONCLUSIONS: FOXO1high neutrophils represent a novel neutrophil phenotype that emerges in response to acute and chronic TBI, which provides insight into the heterogeneity, reprogramming activity, and versatility of neutrophils in TBI.

[Preliminary Study on the Secretory Performance of Mycobacterium tuberculosis Hypoxic Response Protein 1 (Rv2626c)].

OBJECTIVE: To verify the secretory ability of the hypoxic response protein 1 (HRP1) encoded by Mycobacterium tuberculosis (Mtb) Rv2626c. METHODS: The target gene attached with His tag was amplified from the genome of Mtb standard virulence strain H37Rv. The recombinant plasmid contained the above amplified product was constructed and electroporated into Mycobacterium smegmatis (Ms) (MC 2155) to construct a recombinant strain. Protein expression was induced under heat condition, and the expression of protein from the culture filtrates and the bacterial lysates was detected afterward. The 10 kDa culture filtrate antigen (CFP-10) (Ms) and CFP-10 (Mtb) were used as positive controls, and the cytoplasmic protein heat shock protein 65 (GroEL2) (Mtb) was used as negative controls. RESULTS: The HRP1, GroEL2 (Mtb), CFP-10 (Mtb) and CFP-10 (Ms) were successfully amplified by PCR from recombinant plasmid, and sequencing results of the recombinant plasmid is right, confirming the successful construction of the recombinant plasmid. The recombinant Ms was successfully constructed and it could express the proteins GroEL2 (Mtb), HRP1, CFP-10 (Mtb) and CFP-10 (Ms). The target protein HRP1 was detected in both of the lysate and the culture filtrate of the recombinant strain by Western blot, which was consistent with the positive control CFP-10. The negative control GroEL2 (Mtb) was only detected in the bacterial lysate, but not detected in the culture filtrate. CONCLUSION: The protein HRP1 encoded by Mtb Rv2626c can be secreted out of Ms by the secretion system of Ms. It may be a secreted protein and play an important role in the pathogenesis of Mtb.

[Optimizing Mycobacterium Recombineering System (pJV53) to Promote the Screening of the Mycobacterium Mutants].

OBJECTIVE: To establish a way for screening Mycobacterium mutants through adding the screening markers into pJV53. METHODS: The sucrose counter selection gene SacB and mutant hygromycin-resistant gene hygS were inserted into pJV53; The recovery of the hygromycin-resistance indicated the successful homologous recombination in Mycobacterium smegmatis (Ms), which could serve as mutant screening marker; The sucrose counter selection could be used to screen the plasmid-free mutants. RESULTS: The recombinant plasmid pJV53-SacB-hygS were successfully constructed. The rifampin-resistant rpoB D516Y and rpoB H526Q mutants and MSMEG_4487 G188A mutant were efficiently screened out. All mutants had shed the plasmid successfully. CONCLUSION: pJV53-SacB-hygS can efficiently contribute to construct and screen the mutants and to get the mutants shedding the plasmid self, which has high value of extensive application; the D516Y and H526Q mutations in gene rpoB of Mycobacterium tuberculosis contribute to its rifampin-resistance.

[Mycobacterium Tuberculosis Rv3084 Encodes Functional Esterase and Suppresses the Pro-inflammatory Cytokines in vivo].

OBJECTIVE: To explore the biological characteristics of the esterase LipR encoded by Mycobacterium tuberculosis (MTB) Rv3084 and its immunomodulatory function in vivo. METHODS: The LipR gene was amplified from MTB H37Rv strain to construct recombinant expression plasmid. After sequencing, the recombinant plasmid was transformed into E. coli for expression and purification of LipR protein. The expressed protein was confirmed with Western blot assay. The hydrolyzing activity of LipR was detected and the factors affecting LipR enzyme activity were analyzed. Mice were intramuscularly injected with 0.1 mL (containing plasmid DNA 100 µg) recombinant eukaryotic plasmid three times (day 1, 8, and 15); seven days after the last injection, the mice were executed, and the lung and spleen were taken for cytokine detection. RESULTS: The recombinant expression plasmid was successfully constructed and it was found that LipR protein was mainly expressed in the form of inclusion bodies in E. coli with the relative molecular mass of about 33×10 3. LipR was demonstrated as an alkaline eurythermic esterase, due to the preference of hydrolyzing short carbon chain esters with optimal hydrolyzing activity on pNP-acetate (pNPA, C2) and the capability in tolerance of high pH and temperature; in the presence of different detergents or metal ions, the activity of LipR hydrolyzing pNP-butyrate (pNPB, C4) was inhibited to some extent. In the mouse model, it was found that LipR could inhibit the secretion of interferon-γ (IFN- γ) and interleukin-2 (IL-2), but to stimulate the secretion of IL-10. CONCLUSION: The esterase LipR may be one of the esterases help M. tuberculosis withstand harsh environment inside the host in collaboration, and simultaneously act as an immune modulator to inhibit the secretion of pro-inflammatory cytokines and consequently impact the killing effect of host immune system against M. tuberculosis.