Deficiency in the guanine nucleotide exchange factor DOCK8 causes a human immunodeficiency syndrome associated with recurrent sinopulmonary and viral infections. We have recently identified a DOCK8-deficient mouse strain, carrying an ethylnitrosourea-induced splice-site mutation that shows a failure to mature a humoral immune response due to the loss of germinal centre B cells. In this study we turned to T-cell immunity to investigate further the human immunodeficiency syndrome and its association with decreased peripheral CD4+ and CD8+ T cells. Characterisation of the DOCK8-deficient mouse revealed T-cell lymphopenia, with increased T-cell turnover and decreased survival. Egress of mature CD4+ thymocytes was reduced with increased migration of these cells to the chemokine CXCL12. However, despite the two-fold reduction in peripheral naïve T cells, the DOCK8-deficient mice generated a normal primary CD8+ immune response and were able to survive acute influenza virus infection. The limiting effect of DOCK8 was in the normal survival of CD8+ memory T cells after infection. These findings help to explain why DOCK8-deficient patients are susceptible to recurrent infections and provide new insights into how T-cell memory is sustained.

Objective. To address the role of the nuclear receptor 4A (NR4A) family of orphan nuclear receptors in synoviocyte transformation, hyperplasia, and regulation of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in models of inflammatory arthritis.Methods. NR4A messenger RNA levels in synovial tissue and primary synoviocytes were measured by quantitative reverse transcription-polymerase chain reaction (RT-PCR). NR4A2 was stably overexpressed in normal synoviocytes, and cell proliferation, survival, anchorage-independent growth, migration, and invasion were monitored in vitro. MMP and TIMP expression levels were analyzed by quantitative RT-PCR, and MMP-13 promoter activity was measured using reporter assays. Stable depletion of endogenous NR4A levels was achieved by lentiviral transduction of NR4A short hairpin RNA (shRNA), and the effects on proliferation, migration, and MMP-13 expression were analyzed.Results. NR4A2 was expressed at elevated levels in normal, OA, and RA synovial tissue and in primary RA synoviocytes. Tumor necrosis factor ␣ (TNF␣) rapidly and selectively induced expression of NR4A2 in synoviocytes. Ectopic expression of NR4A2 in normal synoviocytes significantly increased proliferation and survival, promoted anchorage-independent growth, and induced migration and invasion. MMP-13 gene expression was synergistically induced by NR4A2 and TNF␣, while expression of TIMP-2 was antagonized. NR4A2 directly transactivated the proximal MMP-13 promoter, and a point mutation in the DNA binding domain of NR4A2 abolished transcriptional activation. Depletion of endogenous NR4A receptors with shRNA reduced synoviocyte proliferation, migration, and MMP-13 expression.Conclusion. The orphan nuclear receptor NR4A2 is a downstream mediator of TNF␣ signaling in synovial tissue. NR4A2 transcriptional activity contributes to the hyperplastic and invasive phenotype of synoviocytes that leads to cartilage destruction, suggesting that this receptor may show promise as a therapeutic target in inflammatory arthritis.

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Background: Sleep disturbance is an issue reported by caregivers. Waking at night is a feature of dementia and by proxy, sleep disturbance among caregivers is reported to be high. Little is known about the characteristics of dementia caregivers' sleep and the factors that may influence sleep disruption. The purpose of this study was to investigate the sleep characteristics and disturbances of Australian caregivers of a person living with dementia. In addition, it evaluated the psychological wellbeing of caregivers by evaluating associations between mood and sleep in this population. Methods: This study used a cross-sectional, descriptive, correlation design. Participants were recruited with the assistance of Alzheimer's Australia, Dementia Australia and targeted social media advertising. In total, 104 adult, primary, informal caregivers of people with dementia participated, completing a questionnaire on demographic characteristics, the Depression, Anxiety and Stress Scale (DASS-21) and the Pittsburgh Sleep Quality Index (PSQI). Results: In this study, 76% of caregivers were female who had been caring for someone living with dementia on average for 4.8 years. 44% of participants had two or more co-morbidities namely cardiovascular disease, osteoarthritis and diabetes. 94% of participants were poor sleepers with 84% with difficulty initiating sleep and 72% reporting having difficulty maintaining sleep. Overall, psychological distress was common with high levels of moderate to severe depression, anxiety and stress. Global PSQI scores were significantly positively associated with depression and anxiety, with the strongest correlation seen with stress scores. Depression scores were also moderately associated with daytime dysfunction. Stress was identified as a significant predictor of overall sleep quality. Conclusions: Sleep problems are common within the population of dementia caregivers. Due to the nature and duration of caregiving and the progression of dementia of the care recipient, there is the potential for a decline in the caregivers' mental and physical health. Caregivers of those living with dementia are more likely to have comorbidities, depression, anxiety and stress. Sleep quality is correlated with emotional distress in dementia caregivers although the direction of this association is unclear. Therefore, sleep and psychological wellbeing may be intertwined, with improvements in one aspect resulting in a positive impact in the other.

Emerging evidence has identified sleep as a significant, but modifiable, risk factor for metabolic syndrome, diabetes, and obesity. Leptin, an adipocyte-derived peptide and a regulator of food intake and energy expenditure, has been shown to be associated with a short sleep duration in the pathophysiology of obesity and consequently type 2 diabetes. This review focuses on the current evidence indicating the effects of a short sleep duration on the regulation of leptin concentration in association with obesity and diabetes mellitus. In summary, the evidence suggests that sleep deprivation, by affecting leptin regulation, may lead to obesity and consequently development of type 2 diabetes through increased appetite and food intake. However, findings on the role of leptin in diabetes due to sleep deprivation are contradictory, and further studies with larger sample sizes are needed to confirm previous findings.