An array of diverse processes and factors have been linked to the pathoetiology and pathophysiology of Parkinson’s disease (PD), including systemic CNS factors. This article reviews some of the many processes and factors linked to the emergence and progression of PD that culminates in the loss of substantia nigra pars compacts (SNpc) in PD patients. It is proposed that SNpc astrocytes may be a key hub, with numerous systemic and CNS factors acting to suppress the astrocyte tryptophan-melatonin pathway, leading to a loss of astrocyte melatonin and lactate for SNpc dopamine neurons. Consequently, dopamine neurons show an increase in α-synuclein, oxidative stress and suboptimal mitochondrial function, partly due to the loss of melatonin induced PTEN-associated kinase (PINK)1/parkin and mitophagy. This leads to an increase in the major histocompatibility (MHC)-1 and the chemoattraction of CD8+ T cells that destroy SNpc dopamine neurons in an ‘autoimmune’/’immune-mediated’ manner. The upstream processes driving the end-point ‘chaos’ of SNpc dopamine neuron loss are proposed to be driven by the suppression of night-time pineal melatonin, gut microbiome derived butyrate and possibly bcl2-associated athanogene (BAG)-1, which all act to suppress the glucocorticoid receptor (GR) translocation to the nucleus in all systemic and CNS cells, thereby potentiating the effects of the rising levels of cortisol over the night and accelerated rise in the course of the cortisol awakening response (CAR). The potentiation of cortisol effects at the GR has consequences for the homeostatic regulation of the diverse array of systemic and CNS microenvironments, as well as a distinct regulation of different immune and glia cells. The morning CAR is classically proposed to ‘prepare the body for the coming day’. However, the differential regulation of the GR over the circadian rhythm at night would indicate that such preparation for the coming day may be powerfully determined by night-time factors and processes. The article integrates this systemic, night-time pathoetiology with the ‘immune-mediated’ processes that ultimately drive SNpc dopamine neuron loss. This has a number of novel future research and treatment implications.

Alzheimer's disease (AD) has been the subject of extensive investigation as to its biological underpinnings. However, this has produced little of therapeutic benefit or indeed provided any accepted biomarkers that could tailor treatment. This chapter reviews data on the main pathophysiologic processes that have been widely shown to be altered in AD, including circadian dysregulation, mitochondrial dysfunction, gut dysbiosis, and immune-glia-platelet activation. It is proposed that alterations in the gut microbiome, including gut dysbiosis and increased gut permeability drive changes in mitochondrial function that are intimately associated with significant variations in sirtuin expression. Both mitochondria-located and nucleus/cytoplasm located sirtuins can act on mitochondrial function in different cells and body systems to co-ordinate the ageing-associated changes that underpin AD. The sirtuins are therefore key aspect to a developmental model of AD that is more 'holistic' in perspective, thereby providing a framework for the detection of earlier biomarkers and more successful treatment for the heterogenous nature of AD pathoetiology.

In this paper we propose a novel theoretical framework, which was previously developed for major depression and bipolar disorder, namely the compensatory immune-regulatory reflex system (CIRS), as applied to the neuro-immune pathophysiology of schizophrenia and its phenotypes, including first episode psychosis (FEP), acute relapses, chronic and treatment resistant schizophrenia (TRS), comorbid depression, and deficit schizophrenia. These schizophrenia phenotypes and manifestations are accompanied by increased production of positive acute phase proteins, including haptoglobin and α2-macroglobulin, complement factors, and macrophagic M1 (IL-1β, IL-6 and TNF-α), T helper (Th)-1 (interferon-γ and IL-2R), Th-2 (IL-4, IL-5), Th-17 (IL-17) and T regulatory (Treg; IL-10 and transforming growth factor (TGF)-β1) cytokines, cytokine-induced activation of the tryptophan catabolite (TRYCAT) pathway as well as chemokines, including CCL-11 (eotaxin), CCL-2, CCL-3 and CXCL-8. While the immune profiles in the different schizophrenia phenotypes indicate activation of the immune-inflammatory response system (IRS), there are simultaneous signs of CIRS activation, including increased levels of the IL-1 receptor antagonist (sIL-1RA), sIL-2R and tumor necrosis factor-a receptors, Th-2 and Treg phenotypes with increased IL-4 and IL-10 production, and increased levels of TRYCATs and haptoglobin, α2-macroglobulin and other acute phase reactants, which have immune-regulatory and anti-inflammatory effects. Signs of activated IRS and CIRS pathways are also detected in TRS, chronic and deficit schizophrenia indicating that these conditions are accompanied by a new homeostatic setpoint between upregulated IRS and CIRS components. In FEP, increased baseline CIRS activity is a protective factor which may predict favorable clinical outcomes. Moreover, impairments in the CIRS are associated with deficit schizophrenia and greater impairments in semantic and episodic memory. It is concluded that CIRS plays a key role in the pathophysiology of schizophrenia by negatively regulating the primary IRS and contributing to recovery from the acute phase of illness. Components of the CIRS may offer promising therapeutic targets for schizophrenia.