Nucleotide-binding oligomerization domain protein 1 (NOD1) belongs to a family that includes multiple members with NOD and leucine-rich repeats in vertebrates and plants. NOD1 has been suggested to have a role in innate immune responses, but the mechanism involved remains unknown. Here we report that NOD1 mediates the recognition of peptidoglycan derived primarily from Gram-negative bacteria. Biochemical and functional analyses using highly purified and synthetic compounds indicate that the core structure recognized by NOD1 is a dipeptide, gamma-D-glutamyl-meso-diaminopimelic acid (iE-DAP). Murine macrophages deficient in NOD1 did not secrete cytokines in response to synthetic iE-DAP and did not prime the lipopolysaccharide response. Thus, NOD1 mediates selective recognition of bacteria through detection of iE-DAP-containing peptidoglycan.

Vesicular glutamate transporters (VGLUT1, ‐2, and ‐3) mediate the accumulation of transmitter glutamate into synaptic vesicles in glutamatergic neurons. VGLUT1 and VGLUT2 are more reliable glutamatergic neuron markers, since VGLUT3 also exists in other neuron types. To study whether the dopaminergic neuron uses glutamate as a cotransmitter, we analyzed VGLUTs expression in dopamine neurons of adult male rats by in situ hybridization and immunohistochemistry. In the ventral midbrain, in situ hybridization analysis revealed no VGLUT1 mRNA expression, a widespread but discrete pattern of VGLUT2 mRNA expression, and a highly limited expression of VGLUT3 mRNA. Reverse‐transcriptase polymerase chain reaction analysis detected full‐length VGLUT2 gene transcripts in the ventral midbrain. Using in situ hybridization combined with tyrosine hydroxylase (TH) immunostaining, only VGLUT2 signals were detectable in some TH‐labeled neurons of A10 dopamine neuron groups, with the highest incidence (20%) in the rostral linear nucleus of the ventral tegmental area. In the forebrain, VGLUT2 signals were demonstrated in half of the A11 TH‐labeled neurons in the hypothalamus. Double‐label immunostaining for VGLUT2 and vesicular monoamine transporter 2 or TH showed that double‐labeled varicosities are rarely observed in any target regions examined of A10 and A11 dopamine neuron groups. These results indicate that VGLUT2 is expressed in subsets of A10 and A11 dopamine neurons, which might release dopamine and glutamate separately from different varicosities in the majority of their single axons. J. Comp. Neurol. 498:581–592, 2006. © 2006 Wiley‐Liss, Inc.

Nod1 is a member of family of intracellular proteins that mediate host recognition of bacterial peptidoglycan. To characterize immune responses mediated by Nod1, synthetic ligand compounds possessing enhanced ability to stimulate Nod1 were developed to study the function of Nod1. Stimulation of epithelial cells with Nod1 stimulatory molecules induced chemokines and other proinflammatory molecules that are important for innate immune responses and recruitment of acute inflammatory cells. Administration of Nod1 ligands into mice induced chemokines and recruitment of acute inflammatory cells, an activity that was abolished in Nod1-null mice. Microarray analysis revealed that Nod1 stimulation induces a restricted number of genes in intestinal epithelial cells compared with that induced by tumor necrosis factor (TNF) α. Nod1 stimulation did not induce TNFα, interleukin 12, and interferon γ, suggesting that the primary role of Nod1 is to induce the recruitment of immune cells. These results indicate that Nod1 functions as a pathogen recognition molecule to induce expression of molecules involved in the early stages of the innate immune response.

Bacterial cell wall peptidoglycan (PGN) is a potent immunostimulator and immune adjuvant. The PGN of Gram-negative bacteria and some Gram-positive bacteria contain meso-diaminopimelic acid (meso-DAP), and we have recently shown that the intracellular protein Nod1 is a PGN receptor and recognizes DAP-containing peptides. In this study, we achieved the synthesis of DAP-containing PGN fragments, including the first chemical synthesis of tracheal cytotoxin (TCT), GlcNAc-(beta1-4)-(anhydro)MurNAc-L-Ala-gamma-D-Glu-meso-DAP-D-Ala, and a repeating-unit of DAP-type PGN, GlcNAc-(beta1-4)-MurNAc-L-Ala-gamma-D-Glu-meso-DAP-D-Ala. For the synthesis of PGN fragments, we first established a new synthetic method for an orthogonally protected meso-DAP derivative, and then we constructed the glycopeptide structures. The ability of these fragments to stimulate human Nod1, as well as differences in Nod1 recognition of the variety of synthesized ligand structures were examined. The results showed that the substitution of the N terminus of iE-DAP is necessary for stronger Nod1 recognition, but the structure of the substituent seems not to be strictly recognized. The importance of the carboxyl group at the 2-position of DAP for human Nod1 stimulation was also shown.

Background: The coronavirus disease 2019 (COVID-19) pandemic has negatively affected the mental health of the general population. Objective: We investigated the determinants of quality of life (QOL) in Parkinson’s disease (PD) patients during the COVID-19 pandemic. Methods: Impacts of lifestyle changes due to the COVID-19 pandemic on 100 patients with PD and their caregivers/spouses were assessed. The Hospital Anxiety and Depression Scale was used to assess anxiety and depression. The physical component summary (PCS) and mental component summary (MCS) scores of the short form (SF)-8 were used to evaluate health-related QOL. Results: Regarding health-related QOL, physical function, role physical, general health, vitality and the PCS score were significantly worse in PD patients than in caregivers. Worsening of PD-related symptoms, increased stress, and decreased physical activity were observed in 29.0%, 37.0% and 44.0% of PD patients, respectively. Sixteen patients (16.0%) experienced problems with hospital access, but none reported medication shortages. Strong concerns about COVID-19 were reported by 47.0% of caregivers and 50.0% of PD patients. In PD patients, increased gait disturbance and rigidity, disease severity, smoking, the levodopa equivalent dose and decreased body weight predicted a worse PCS score; anxiety, depression, female sex, stress and long disease duration predicted a worse MCS score. In caregivers, age and smoking contributed to a worse PCS score; depression, stress and worsening patient mood contributed to a worse MCS score. Conclusion: We report the negative impacts of the COVID-19 pandemic on health-related QOL and its determinants in PD patients and their caregivers.