Salmonella flagellin induces bystander activation of splenic dendritic cells and hinders bacterial replication in vivo

Bacterial flagellin is a target of innate and adaptive immune responses during Salmonella infection. Intravenous injection of Salmonella flagellin into C57BL/6 mice induced rapid IL-6 production and increased expression of activation markers by splenic dendritic cells. CD11b(+), CD8alpha(+), and plasmacytoid dendritic cells each increased expression of CD86 and CD40 in response to flagellin stimulation, although CD11b(+) dendritic cells were more sensitive than the other subsets. In addition, flagellin caused the rapid redistribution of dendritic cells from the red pulp and marginal zone of the spleen into the T cell area of the white pulp. Purified splenic dendritic cells did not respond directly to flagellin, indicating that flagellin-mediated activation of splenic dendritic cells occurs via bystander activation. IL-6 production, increased expression of activation markers, and dendritic cell redistribution in the spleen were dependent on MyD88 expression by bone marrow-derived cells. Avoiding this innate immune response to flagellin is important for bacterial survival, because Salmonella-overexpressing recombinant flagellin was highly attenuated in vivo. These data indicate that flagellin-mediated activation of dendritic cells is rapid, mediated by bystander activation, and highly deleterious to bacterial survival.     

Missing Dosages and Neuroleptic Usage May Prolong Length of Stay in Hospitalized Parkinson's Disease Patients

Background

Parkinson’s disease patients are more likely to be hospitalized, have higher rates of hospital complications, and have an increased risk of deterioration during hospitalization. Length of stay is an important underlying factor for these increased risks. We aimed to investigate potential medication errors that may occur during hospitalization and its impact on length of hospital stay.

Methods

A cross-sectional chart review of 339 consecutive hospital encounters from 212 PD subjects was performed. Medication errors were defined as wrong timing or omission of administration for dopaminergic drugs and administration of contraindicated dopamine blockers. An analysis of covariance was applied to examine whether these medication errors were related to increased length of hospital stays.

Results

A significant effect for dopaminergic administration (p<0.01) on length of hospital stay was observed. Subjects who had delayed administration or missed at least one dose stayed longer (M=8.2 days, SD=8.9 vs. M=3.6 days SD=3.4). Contraindicated dopamine blocking agents were administered in 23% (71/339) of cases, and this was also significantly related to an increased length of stay (M=8.2 days, SD=8.9 vs. M=3.6 days SD=3.4), p<0.05. Participants who received a contraindicated dopamine blocker stayed in the hospital longer (M=7.5 days, SD=9.1) compared to those who did not (M=5.9 days, SD=6.8). Neurologists were consulted in 24.5% of encounters. Specialty consultation had no effect on the medication related errors.

Conclusions

Missing dopaminergic dosages and administration of dopamine blockers occur frequently in hospitalized Parkinson’s disease patients and this may impact length of stay. These potentially modifiable factors may reduce the risk of a longer stay related to hospitalization.     

Insights from the predicted epitope similarity between Mycobacterium tuberculosis virulent factors and its human homologs

Mycobacterium tuberculosis is known to be associated with several autoimmune diseases such as systemic lupus erythematous, rheumatoid arthritis and multiple sclerosis. This is attributed to sequence similarity between virulent factors and human proteins. Therefore, it is of interest to identify such regions in the virulent factors to assess potential autoimmune related information. M. tb specific virulent factors were downloaded from the VFDB database and its human homologs were identified using the sequence comparison search tool BLASTP. Both virulent proteins and their corresponding human homologs were further scanned for epitopes (B cell and HLA class I and II allele specific) using prediction programs (BCPRED and NETMHC). Data shows the presence of matching 22 B-cell, 79 HLA class II and 16 HLA class I specific predicted epitopes in these virulent factors having human homologs. A known peptide (HAFYLQYKNVKVDFA) associated with autoimmune atopic dermatitis is shown in the superoxide dismutase homolog structures of the bacterium (PDB ID: 1IDS) and human (PDB ID: 2QKC). This data provides insight into the understanding of infection-associated auto-immunity     

RPA70 depletion induces hSSB1/2-INTS3 complex to initiate ATR signaling

The primary eukaryotic single-stranded DNA-binding protein, Replication protein A (RPA), binds to single-stranded DNA at the sites of DNA damage and recruits the apical checkpoint kinase, ATR via its partner protein, ATRIP. It has been demonstrated that absence of RPA incapacitates the ATR-mediated checkpoint response. We report that in the absence of RPA, human single-stranded DNA-binding protein 1 (hSSB1) and its partner protein INTS3 form sub-nuclear foci, associate with the ATR-ATRIP complex and recruit it to the sites of genomic stress. The ATRIP foci formed after RPA depletion are abrogated in the absence of INTS3, establishing that hSSB-INTS3 complex recruits the ATR-ATRIP checkpoint complex to the sites of genomic stress. Depletion of homologs hSSB1/2 and INTS3 in RPA-deficient cells attenuates Chk1 phosphorylation, indicating that the cells are debilitated in responding to stress. We have identified that TopBP1 and the Rad9-Rad1-Hus1 complex are essential for the alternate mode of ATR activation. In summation, we report that the single-stranded DNA-binding protein complex, hSSB1/2-INTS3 can recruit the checkpoint complex to initiate ATR signaling.     

Expression and mutagenesis of the dpsA gene of Synechococcus sp. PCC7942, encoding a DNA-binding protein involved in oxidative stress protection

The Dps family of proteins are a diverse group of bacterial stress-inducible polypeptides that bind DNA and likely confer resistance to peroxide damage during periods of oxidative stress and long-term nutrient limitation. Some members of the Dps protein family have been shown to form abundant, large (∼150 kD) hexameric complexes that bind chromosomal DNA with little sequence specificity. Previous work from this lab has demonstrated that the Dps proteins are divergent members of the bacterioferritin/bacterioferritin superfamily, and that the Synechococcus sp. PCC7942 Dps homolog, named DpsA, is a DNA-binding hemoprotein having heme-dependent catalytic activity. We speculated that this protein may yield a peroxide-consuming mechanism located on the chromosomal DNA, and we also suggested that this activity may be a necessary feature to handle the endogenous oxidative stresses associated with oxygenic photosynthesis. Current work has examined the expression of dpsA both under nutrient stress and during the growth phase; whereas dpsA mRNA is detectable in the exponential phase, transition to stationary phase yields a 20-fold increase in steady-state mRNA levels. Mapping the promoter region identifies a TAGAAT −10 sequence likely recognized by a cyanobacterial RpoS homolog. Lastly, site-directed mutants lacking dpsA function exhibit a severe phenotype impaired under all conditions yielding photooxidative stress; these include high light and treatment with paraquat. This supports our contention that the DpsA protein serves an important protective function in an obligate photoautotroph.     

Diversity and distribution of the tick-borne relapsing fever spirochete Borrelia turicatae

Borrelia turicatae is a causative agent of tick-borne relapsing fever (TBRF) in the subtropics and tropics of the United States and Latin America. Historically, B. turicatae was thought to be maintained in enzootic cycles in rural areas. However, there is growing evidence that suggests the pathogen has established endemic foci in densely populated regions of Texas. With the growth of homelessness in the state and human activity in city parks, it was important to implement field collection efforts to identify areas where B. turicatae and its vector circulate. Between 2017 and 2020 we collected Ornithodoros turicata ticks in suburban and urban areas including public and private parks and recreational spaces. Ticks were fed on naïve mice and spirochetes were isolated from the blood. Multilocus sequence typing (MLST) was performed on eight newly obtained isolates and included previously reported sequences. The four chromosomal loci targeted for MLST were 16S ribosomal RNA (rrs), flagellin B (flaB), DNA gyrase B (gyrB), and the intergenic spacer (IGS). Given the complexity of Borrelia genomes, plasmid diversity was also evaluated. These studies indicate that the IGS locus segregates B. turicatae into four genomic types and plasmid diversity is extensive between isolates. Furthermore, B. turicatae and its vector have established endemic foci in parks and recreational areas in densely populated settings of Texas.     

Covaxin: An overview of its immunogenicity and safety trials in India

The spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to a global coronavirus disease-19 (COVID-19) pandemic. Several vaccine types, such as inactivated, viral vector-, or mRNA-based, have received approval against SARS-CoV-2. The ability to induceT-helper-1 cell (Th1) responses is desirable from an effective vaccine against this virus. Covaxin (BBV152) is a wholevirion inactivated SARS-CoV-2 vaccine adjuvanted with Algel-Imidazoquinoline (IMDG) molecule, a toll-like receptor (TLR) 7/8 agonist. The mRNA-based vaccine use is hindered because of cold storage requirement, whereas covaxin is stored between 2°C and 8°C, making it suitable for countries with limited resources. The Drug Controller General of India (DCGI) has approved the BBV152 vaccine. Therefore, it is of interest to document known data on BBV152 vaccine phase I, phase II and phase III human clinical trials to evaluate the safety, reactogenicity, tolerance, and immunogenicity of the whole-virion inactivated SARS-CoV-2 vaccine (BBV152).     

Effect of wet and dry cycles in calcareous soil on mineral nutrient uptake of two grasses,Agrostis stolonifera L. and Festuca ovina L.

Shoot uptake of mineral nutrients (Ca, Cu, Fe, K, mg, Mn, P, S, Zn) by Agrostis stolonifera L. was compared with Festuca ovina L. under wet and dry cycles. Such conditions are typical for A. stolonifera sites, whereas F. ovina is growing mostly on consistently drier and better-drained soils. Plants were grown in a glasshouse, at controlled temperature and light conditions, using two moisture regimes, one constant at 60% WHC (water holding capacity), one wet/dry fluctuating between 35 and 100% WHC. Above ground and total biomass production was lower under wet/dry treatment than at constant water regime in F. ovina, but did not differ between regimes in A. stolonifera. Shoot uptake of most elements was severely reduced in F. ovina at the wet/dry regime. Shoot uptake and concentrations of most elements studied (Cu, K, Mn, P, S, Zn) were lower (p<0.05) under wet/dry treatment than at constant regime in A. stolonifera and tended to be lower also of Fe and Mg. Differences in biomass production observed are consistent with field evidence that A. stolonifera grows in sites which are periodically flooded but may become quite dry during other periods, and that F. ovina is limited to sites which are consistently drier and better drained. Evidence from the present study, however, does not support any view that alternating wet and dry cycles, as typical of A. stolonifera field sites, would be beneficial to nutrient acquisition of this species but that biomass production may develop normally at the lower uptake of most mineral nutrients measured under the wet/dry regime. Such regimes are decidedly unfavourable to both growth and nutrient acquisition of F. ovina.     

An Appraisal of Ancient Molecule GABA in Abiotic Stress Tolerance in Plants,and Its Crosstalk with Other Signaling Molecules

Gamma-aminobutyric acid (GABA), a non-proteinaceous amino acid, is reported in prokaryotes and eukaryotes, since ancient times. However, it has gained attention in the present time because of its rapid accumulation during stressed conditions in plants as well as in the cyanobacteria. In plants, it regulates the number of physiological processes such as pollen tube growth, root growth, TCA cycle, N₂-metabolism, and osmoregulation. Several biotic and abiotic stresses prevail in the environment, which lead to enhanced accumulation of reactive oxygen species (ROS) thus causing oxidative damage. However, a rapid increase in the accumulation of GABA during stress in various plant forms like bacteria, cyanobacteria, fungi, and plants indicates its putative role in stress regulation and acclimation. This review summarizes the biosynthesis of GABA, its role in abiotic stress tolerance, and its crosstalk with ROS, nitric oxide, Ca⁺² ions, phytohormones, and polyamines in stress acclimation.