Exogenous hydrogen sulfide ameliorates diabetes-associated cognitive dysfunction by regulating the nrf-2/HO-1 axis and the NLRP3 inflammasome pathway in diabetic rats.

Diabetes-associated cognitive dysfunction (DACD) is a complication of diabetes mellitus that leads to an increased risk of cognitive impairment and dementia. However, the molecular mechanism underlying DACD has not been elucidated, and a promising therapy for this disease remains to be established. Hydrogen sulfide (H2S), a significant antioxidative and anti-inflammatory gasotransmitter, has emerged as a neuroprotective agent. In this study, we investigated the protective effects of H2S on DACD in a streptozotocin (STZ)-induced diabetic rat model. We applied the Morris water maze to evaluate spatial learning and memory abilities. We used Western blotting and immunohistochemical staining to investigate the expression of the Nrf-2/HO-1 axis and the NLRP3 inflammasome. After NaHS (H2S donor) administration, diabetic rats exhibited improved spatial learning and memory retrieval abilities in the Morris water maze. In STZ-induced diabetic rats, the protein expression levels of the Nrf-2/HO-1 axis, the NLRP3 inflammasome and subsequent inflammatory cytokines in the hippocampal region were elevated compared to those in control rats. Exogenous H2S triggered Nrf-2/HO-1 antioxidant activity and inhibited NLRP3 inflammasome activation and proinflammatory cytokine expression. These findings suggested that exogenous H2S has neuroprotective effects by modulating the Nrf-2/HO-1 axis and the NLRP3 inflammasome pathway, which were found to be associated with DACD. H2S treatment may be a promising therapeutic strategy for preventing the progression of tissue damage caused by DACD.

Intracerebral Hemorrhage-Induced Brain Injury: the Role of Lysosomal-Associated Transmembrane Protein 5.

Intracerebral hemorrhage (ICH) is a lethal stroke with high mortality or disability. However, effective therapy for ICH damage is generally lacking. Previous investigations have suggested that lysosomal protein transmembrane 5 (LAPTM5) is involved in various pathological processes, including autophagy, apoptosis, and inflammation. In this study, we aimed to identify the expression and functions of LAPTM5 in collagenase-induced ICH mouse models and hemoglobin-induced cell models. We found that LAPTM5 was highly expressed in brain tissues around the hematoma, and double immunostaining studies showed that LAPTM5 was co-expressed with microglia cells, neurons, and astrocytes. Following ICH, the mice presented increased brain edema, blood-brain barrier permeability, and neurological deficits, while pathological symptoms were alleviated after the LAPTM5 knockdown. Adeno-associated virus 9-mediated downregulation of LAPTM5 also improves ICH-induced secondary cerebral damage, including neuronal degeneration, the polarization of M1-like microglia, and inflammatory cascades. Furthermore, LAPTM5 promoted activation of the nuclear factor kappa-B (NF-κB) pathway in response to neuroinflammation. Further investigations indicated that brain injury improved by LAPTM5 knockdown was further exacerbated after the overexpression of receptor-interacting protein kinase 1 (RIP1), which is revealed to trigger the NF-κB pathway. In vitro experiments demonstrated that LAPTM5 silencing inhibited hemoglobin-induced cell function and confirmed regulation between RIP1 and LAPTM5. In conclusion, the present study indicates that LAPTM5 may act as a positive regulator in the context of ICH by modulating the RIP1/NF-κB pathway. Thus, it may be a candidate gene for further study of molecular or therapeutic targets.

Exogenous Hydrogen Sulfide Ameliorates Diabetes-Associated Cognitive Decline by Regulating the Mitochondria-Mediated Apoptotic Pathway and IL-23/IL-17 Expression in db/db Mice.

BACKGROUND: Diabetes-associated cognitive decline (DACD) is one of the complications of diabetes and leads to cognitive impairment and an increased risk of dementia. However, the exact mechanism of DACD has not been fully characterized, and a successful therapy for this issue has not been established. This study aimed to detect the anti-apoptotic and anti-inflammatory effects of hydrogen sulfide (H2S) on DACD. METHODS: We used a behavioural scoring method, Western blot, TUNEL staining and immunofluorescence staining to investigate the expression of the mitochondrial apoptotic pathway and the IL-23/IL-17 axis in db/db mice with or without sodium hydrosulfide (NaHS) administration. RESULTS: NaHS administration mice exhibited reduced time to find the platform and a shorter swimming distance (P<0.05), while the time spent in the target quadrant was increased compared to that of the db/db group (P<0.05). Pro-apoptotic proteins, including cleaved Caspase-3, cleaved Caspase-9, Bax and cytochrome C, were elevated in the db/db group (P<0.01) but were downregulated in the db/db+NaHS group (P<0.05). Exogenous H2S decreased the numbers of TUNEL-positive cells in the db/db mice (P<0.05). The Western blot analysis showed that the expression levels of IL-23/IL-17 were lower in the NaHS administration group than in the db/db group (P<0.05). CONCLUSION: We demonstrated that H2S improved the spatial learning and memory abilities of the db/db mice by modulating the mitochondrial apoptotic pathway and the IL-23/IL-17 axis, which were found to be associated with DACD. H2S treatment may help prevent the progression of apoptotic hippocampal neurons in db/db mice and inform the development of a new therapeutic target.

Administration of SB203580, a p38 MAPK Inhibitor, Reduced the Expression of MMP9, and Relieved Neurologic Severity in the Experimental Autoimmune Neuritis (EAN) in Rats.

Dysfunctional expression of matrix metalloproteinase-9 (MMP-9) has been found to be closely associated with the experimental autoimmune neuritis (EAN). In this study, we explored the role of p38 mitogen-activated protein kinases (p38 MAPK) in the regulation of MMP-9 in sciatic nerves of EAN rats. We analyzed the expression changes of MMP-2, MMP-3, MMP-9, and mitogen-activated protein kinases (MAP kinases) in sciatic nerves of EAN rats and investigated the effect of p38 MAPK inhibitor (SB203580) on MMP-9 expression and pathological changes in EAN. Real-time PCR and western blot analyses showed that the expression of MMP-2 exhibited no significant changes throughout the course of EAN, while MMP-3 and MMP-9 presented the relatively increased expression compared with that in control group. MAP kinases, including p38 MAPK, ERK1/2, and JNK1/2, were activated in the sciatic nerve of EAN rats, and phosphorylated p38 MAPK showed similar patterns of expression to MMP-9. The expression of MMP-9 and phosphorylated p38 MAPK in sciatic nerves were in positive correlation with disease severity. In addition, SB203580 treatment significantly reduced the mRNA and protein level of MMP-9 in sciatic nerves on the peak phase of EAN. Inhibition of p38 MAPK also relieved neurologic severity and ameliorated pathological changes in EAN. In conclusion, SB203580 may ameliorate clinical deficit and pathological changes in EAN by reducing the MMP-9 expression in sciatic nerves, which suggest that p38 MAPK inhibitor such as SB203580 could be considered as a therapeutic candidate in autoimmune neuropathies.

The immunomodulatory effect of bone marrow stromal cells (BMSCs) on interleukin (IL)-23/IL-17-mediated ischemic stroke in mice.

Ischemic cerebral infarction is a leading cause of death and disability, but the key inflammatory cytokines were not fully understood and no successful therapy has been established. We have used the methods of reverse transcriptase-polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), western blot, and immunohistochemical staining to detect the dynamic changes of IL-23/IL-17 axis in brain infarction and BMSC treatment on the sixth day. BMSC transplantation could reduce the infarct size (P<0.05) and improve functional deficits (P<0.001) in brain infarction. The level of IL-23/IL-17 axis expression is higher (P<0.05) in pMCAO-operated group than that in sham operated group. BMSC treatment could reduce IL-23 expression (P<0.05) and attenuate IL-17 expression (P<0.01) both in serum and around infarct lesion. So we have drawn the conclusion that IL-23/IL-17 axis induces inflammation in the pathophysiological process of cerebral infarction. BMSC treatment plays therapeutic role by immunomodulating the expression of IL-23/IL-17 axis. These findings may help to understand the cytokines in cerebral infarction and open up a possible new way of immunological treatment.