Biomarkers in schizophrenia: A focus on blood based diagnostics and theranostics

Abstract

Identifying biomarkers that can be used as diagnostics or predictors of treatment response (theranostics) in people with schizophrenia (Sz) will be an important step towards being able to provide personalized treatment. Findings from the studies in brain tissue have not yet been translated into biomarkers that are practical in clinical use because brain biopsies are not acceptable and neuroimaging techniques are expensive and the results are inconclusive. Thus, in recent years, there has been search for blood-based biomarkers for Sz as a valid alternative. Although there are some encouraging preliminary data to support the notion of peripheral biomarkers for Sz, it must be acknowledged that Sz is a complex and heterogeneous disorder which needs to be further dissected into subtype using biological based and clinical markers. The scope of this review is to critically examine published blood-based biomarker of Sz, focusing on possible uses for diagnosis, treatment response, or their relationship with schizophreniaassociated phenotype. We sorted the studies into six categories which include: (1) brain-derived neurotrophic factor; (2) inflammation and immune function; (3) neurochemistry; (4) oxidative stress response and metabolism; (5) epigenetics and microRNA; and (6) transcriptome and proteome studies. This review also summarized the molecules which have been conclusively reported as potential blood-based biomarkers for Sz in different blood cell types. Finally, we further discusses the pitfall of current blood-based studies and suggest that a prediction model-based, Sz specific, blood World Journal of Psychiatry W J P oriented study design as well as standardize blood collection conditions would be useful for Sz biomarker development.

Identifying a gene expression signature of cluster headache in blood

“…CD28 and interleukin-4 (IL-4)), metabolism and oxidation might be involved in cluster headache. Although these findings should be interpreted with caution as inflammation-related processes seem to show up rather frequently in gene expression studies in blood2829, inflammatory mediators such as IL-2 and soluble adhesion molecules have repeatedly been associated with cluster headache11123031. Abnormal expression of inflammatory genes in cluster headache was also observed in one of the earlier gene expression profiling studies25, although the genes identified in that study did not overlap with the genes found in our gene expression analysis.…”

Interleukin-1β/Interleukin10 Ratio Produced by Monocytes as a Biomarker of Neuroinflammation in Autism

“…Apart from stress responses, inflammation in the other organ systems, can also affect the brain functions. This could occur via soluble inflammatory mediators, activated immune cells migrating into the brain, and peripheral nervous system feedback [10,[27][28][29]. These factors are also implicated in neuropsychiatric symptoms manifested in patients with systemic autoimmune and/or inflammatory conditions [27,30].…”

Circulating biomarkers in schizophrenia: a proteomics perspective

“…Nonetheless, the fact that SCZ is a very complex and heterogeneous disorder should always be taken into account [91]. Moreover, it is even suggested that further knowledge of the disease pathophysiology and higher stratification of the patients may be needed, where biological and clinical markers may help distinguish different subsets of SCZ patients and may not have the classical diagnostic potential (SCZ versus non-SCZ) [92,93].…”

“…Additionally, some important factors are frequently overlooked in screening studies, such as comparing if the candidate proteins show similar patterns in other psychiatric diseases, meaning that those alterations may arise from common phenotypes of the pathologies and not be an indication of the unique traits [93], which is the final goal of a biomarker.…”

“…In order to decrease study variation, blood collection protocols should have all identical time of collection, must use the same coagulants and blood processing methods, where these methods should be extensively and accurately described [93]. Furthermore, standardized collection also allows investigators to replicate studies with samples that match the initial pilot data.…”