Dihydroxyphenylacetaldehyde Lowering Treatment Improves Locomotor and Neurochemical Abnormalities in the Rat Rotenone Model: Relevance to the Catecholaldehyde Hypothesis for the Pathogenesis of Parkinson's Disease

The catecholaldehyde hypothesis for the pathogenesis of Parkinson's disease centers on accumulation of 3,4-dihydroxyphenylacetaldehyde (DOPAL) in dopaminergic neurons. To test the hypothesis, it is necessary to reduce DOPAL and assess if this improves locomotor abnormalities. Systemic administration of rotenone to rats reproduces the motor and central neurochemical abnormalities characterizing Parkinson's disease. In this study, we used the monoamine oxidase inhibitor (MAOI) deprenyl to decrease DOPAL production, with or without the antioxidant N-acetylcysteine (NAC). Adult rats received subcutaneous vehicle, rotenone (2 mg/kg/day via a minipump), or rotenone with deprenyl (5 mg/kg/day i.p.) with or without oral NAC (1 mg/kg/day) for 28 days. Motor function tests included measures of open field activity and rearing. Striatal tissue was assayed for contents of dopamine, DOPAL, and other catechols. Compared to vehicle, rotenone reduced locomotor activity (distance, velocity and rearing); increased tissue DOPAL; and decreased dopamine concentrations and inhibited vesicular sequestration of cytoplasmic dopamine and enzymatic breakdown of cytoplasmic DOPAL by aldehyde dehydrogenase (ALDH), as indicated by DA/DOPAL and DOPAC/DOPAL ratios. The addition of deprenyl to rotenone improved all the locomotor indices, increased dopamine and decreased DOPAL contents, and corrected the rotenone-induced vesicular uptake and ALDH abnormalities. The beneficial effects were augmented when NAC was added to deprenyl. Rotenone evokes locomotor and striatal neurochemical abnormalities found in Parkinson's disease, including DOPAL buildup. Administration of an MAOI attenuates these abnormalities, and NAC augments the beneficial effects. The results indicate a pathogenic role of DOPAL in the rotenone model and suggest that treatment with MAOI+NAC might be beneficial for Parkinson's disease treatment.

Primary exposure to SARS-CoV-2 variants elicits convergent epitope specificities, immunoglobulin V gene usage and public B cell clones

An important consequence of infection with a SARS-CoV-2 variant is protective humoral immunity against other variants. The basis for such cross-protection at the molecular level is incompletely understood. Here we characterized the repertoire and epitope specificity of antibodies elicited by Beta, Gamma and ancestral variant infection and assessed their cross-reactivity to these and the more recent Delta and Omicron variants. We developed a high-throughput approach to obtain immunoglobulin sequences and produce monoclonal antibodies for functional assessment from single B cells. Infection with any variant elicited similar cross-binding antibody responses exhibiting a remarkably conserved hierarchy of epitope immunodominance. Furthermore, convergent V gene usage and similar public B cell clones were elicited regardless of infecting variant. These convergent responses despite antigenic variation may represent a general immunological principle that accounts for the continued efficacy of vaccines based on a single ancestral variant.

Viral co-pathogens in COVID-19 acute respiratory syndrome - what did we learn from the first year of pandemic?

Objective

: This study aimed to describe the distribution of respiratory pathogens and the occurrence of co-pathogens during the first year of the COVID-19 pandemic.

Methods

We used a multiplex polymerase chain reaction (PCR) panel targeting 23 microorganisms to analyze the oro-pharyngeal samples of patients admitted to our hospital with acute respiratory infection (ARI) between March 1, 2020, and February 28, 2021. We matched 40 to 50 patients who were SARS-CoV-2 positive and SARS-CoV-2 negative per month for age and sex.

Results

A total of 939 patients with multiplex PCR test results were included in the study. Respiratory pathogens where detected in only 8/476 (1.6%) patients with COVID-19 versus 87/463 (18.7%) patients with non–COVID-19 ARI patients. Diversity and rates of pathogens vastly differed from previous years but showed seasonal variance.

Conclusion

Patients with SARS-CoV-2 infection presenting with ARI during the first year of the COVID-19 pandemic demonstrated paucity of respiratory co-pathogens.

Abstract 024: Melatonin Abolishes Renal Infiltration of T Lymphocytes in a High Salt Diet Induced Hypertension Model

Objective: Low grade inflammation and oxidative stress play a role in the pathogenesis of cardiovascular diseases, including hypertension (HTN). There is emerging evidence that the immune system, and particularly the adaptive immune response, may be involved in the triggering of these processes. In a previous study we demonstrated that melatonin prevents kidney damage in salt induced HTN model by decreasing oxidative stress. We hypothesized that this effect is involving the immunomodulation properties of melatonin.

Design and method: Dahl salt sensitive (DSS) rats were fed normal chow [control (Ctrl)], or high salt diet (HSD) or HSD and melatonin (Mel) (30/mg/kg/day) in their water for 8 weeks (n=8 each group). By the end of the treatment or when rats were considered ill with less than 24 hours survival, rats were sacrificed and kidneys were harvested for immediate lymphocytes isolation and characterization by FACS (CD3+CD4+ and CD3+CD8+) and for chemoatractants (vcam-1, cxcl1, cxcl9, cxcl10, cxcl11, cxcl12, cxcl16, cx3cl1,ccl3, ccl4, ccl7, ccl12, ccl17,ccl 19, ccl21) gene expression studies.

Results: HSD was associated with significant renal infiltration of CD4+ and CD8+ T lymphocytes compare to control (0.16±0.02 vs. 5.18±1.6 and 0.95±0.15 vs. 4.6±0.75, % of CD3+ cell , Ctrl vs. HSD, CD4+ and CD8+ respectively, p<0.05). Melatonin treatment significantly reduced renal lymphocytes infiltration (0.7±0.2 and 1.37±0.45 % of CD3+ cells, CD4+ and CD8+ respectively, p<0.05 vs. HSD). HSD increased significantly mRNA expression of renal vcam-1, cxcl1, cxcl9, cxcl10, cxcl11, cxcl16, ccl3, ccl7, ccl21 (2±0.2, 3.1±0.1, 5.2±1.2, 2.4±0.3, 6.3±1, 1.9±0.08, 3±0.4, 3±0.7, 4.8±0.7, time fold, respectively, HSD vs. Ctrl, p<0.05). Adding melatonin to HSD prevented the increase in mRNA expression of cxcl1, cxcl9, cxcl10, cxcl11, cxcl16, ccl7 and ccl21, which are lymphocytes attractants.

Conclusion: Treating HSD fed rats with melatonin decreased renal lymphocytes chemoatractants mRNA expression and is associated with significant reduction of renal T lymphocytes infiltration.