Neutrophil to Lymphocyte Ratio in Patients With a First Episode of Psychosis: A Two-Year Longitudinal Follow-up Study

Complete blood count-based inflammation indexes and symptom severity in people with schizophrenia spectrum disorders: An analysis based on structural equation modelling

INTRODUCTION

Schizophrenia spectrum disorders (SSDs) are associated with immune-inflammatory activation. Recently, complete blood count (CBC)-based inflammation indexes such as the neutrophil-to-lymphocyte ratio (NLR), the monocyte-to-lymphocyte ratio (MLR), and the platelet-to-lymphocyte ratio (PLR) have emerged as reproducible and cost-effective inflammation markers in mental disorders. In this study, we aimed at investigating the relationship of NLR, MLR, and PLR with symptom severity in people with SSDs, testing interactions with relevant clinical variables.

METHODS

We included inpatients with SSDs aged 18-65 consecutively hospitalized from May 2020 to March 2024. Socio-demographic and clinical data were recorded. CBC-based ratios were estimated from routinely collected blood samples. Structural equation modelling (SEM) was performed to test relationships involving symptom severity constructs and CBC-based ratios, accounting for substance use disorder, antipsychotic treatment, and obesity.

RESULTS

Two hundred sixty-six participants met inclusion criteria. The SEM analysis uncovered a significant relationship of MLR with positive (coeff.: 0.19, p=0.048) and negative (coeff.: 0.27, p=0.004) symptoms, also showing a significant link of substance use disorder and antipsychotic treatment with symptom severity as well as of antipsychotic treatment with obesity.

CONCLUSIONS

Notwithstanding the cross-sectional design and the somewhat limited sample representativeness, this study showed a significant relationship between the MLR - but not the NLR or the PLR - and the severity of both positive and negative symptoms, testing at the same time the interactions with other clinical variables. Considering the insufficiency and inconsistency of data in this field, further research is needed to validate our findings and elucidate the underlying mechanisms driving the observed relationships between the MLR and SSD symptoms.

Evaluation of inflammatory markers obtained from complete blood count in different stages of schizophrenia

OBJECTIVE

Systemic inflammatory biomarkers recently studied in schizophrenia include neutrophil/lymphocyte ratio (NLR), monocyte/lymphocyte ratio (MLR), platelet/lymphocyte ratio (PLR), systemic immune inflammation index (SII), and systemic inflammation response index (SIRI). SIRI, a novel inflammatory marker, has not been studied in different stages of schizophrenia. We aimed to compare NLR, MLR, PLR, SII, and SIRI values between psychotic exacerbation and remission values of the same patients with schizophrenia and a healthy control group.

METHOD

In this study, 86 patients with schizophrenia who were hospitalized due to psychotic relapse, the same patient group who were in remission after treatment, and 86 age-sex-matched healthy control subjects were analyzed. Inflammatory marker values of the patient group in both the psychotic exacerbation (PE) and the remission (R) period were analyzed and compared with healthy controls (HC).

RESULTS

NLR, MLR, PLR, SII, and SIRI values were significantly higher in the schizophrenia-PE group than in the HC group. NLR, MLR, SII, and SIRI values were significantly higher in the schizophrenia-PE group than in the schizophrenia-R group. MLR values were significantly higher in the schizophrenia-R group than in the HC group.

CONCLUSION

These findings may be interpreted as NLR, SII, and SIRI, which may be considered as state biomarkers, and MLR may be a trait marker for schizophrenia.

Neutrophil/lymphocyte ratio and cognitive performances in first-episode patients with schizophrenia and healthy controls

Abnormal immune and inflammatory responses are considered to contribute to schizophrenia (SZ). The neutrophil/lymphocyte ratio (NLR) is an inexpensive and reproducible marker of systemic inflammatory responses. Accumulating studies have demonstrated that NLR values are increased in SZ compared to healthy controls and closely related to clinical symptoms in antipsychotic-naïve first-episode SZ (ANFES) patients. However, to our knowledge, only one study has examined NLR in relation to neurocognition in 27 first-episode psychosis patients and 27 controls. This study aimed to examine the relationship of NLR values with cognitive performances in ANFES patients with a larger sample size. Whole blood cell counts were measured in ninety-seven ANFES patients and fifty-six control subjects. The neurocognitive functions of all subjects were measured by the repeatable battery for the assessment of neuropsychological status (RBANS). ANFES patients performed worse on cognition and had increased NLR values relative to healthy controls. In addition, increased NLR was negatively associated with cognitive functions in ANFES patients. Lymphocyte count was positively correlated with cognitive functions in patients. These findings suggest that the abnormal immune and inflammation system indicated by NLR may be involved in the cognitive functions in ANFES patients.

Elevated serum kynurenic acid in individuals with first-episode psychosis and insufficient response to antipsychotics

The tryptophan-metabolizing kynurenine pathway (KP) can be activated by enhanced inflammatory responses and has been implicated in the pathophysiology of schizophrenia. However, there is little evidence for KP dysregulation in the early course of psychotic illness. We aimed to investigate the potential immune-mediated hyperactivity of KP in individuals with first-episode psychosis (FEP) and the relationship with symptom severity and treatment response outcomes. Serum immunoassays were performed to measure peripheral levels of inflammatory cytokines (IL-1β, IL-10, TNF-a), KP rate-limiting enzymes (IDO/TDO), and kynurenic acid (KYNA) metabolite in 104 antipsychotic-naïve patients with FEP and 80 healthy controls (HC). The Positive and Negative Syndrome Scale (PANSS) and the Global Assessment of Functioning Scale (GAF) were administered to assess psychopathology and functioning status at admission and following 4-week treatment with antipsychotics. Cytokine and KP components levels were substantially increased in FEP patients compared to HC, before and after antipsychotic treatment. A significant positive correlation between pro-inflammatory IL-1β and KYNA levels was observed among FEP patients, but not in HC. Importantly, within-patient analysis revealed that those with higher baseline KYNA experienced more severe negative symptoms and poorer clinical improvement at follow-up. These findings suggest that KP is upregulated in early psychosis, likely through the induction of IL-1β-dependent pathways, and raised peripheral KYNA might represent a promising indicator of non-response to antipsychotic medication in patients with FEP.

Blood Cell Count Ratios at Baseline are Associated with Initial Clinical Response to Clozapine in Treatment-Resistant, Clozapine-Naïve, Schizophrenia-Spectrum Disorder

BACKGROUND

Clozapine is the recommended treatment for managing treatment-resistant schizophrenia (TRS), and immunological mechanisms may be involved in its unique antipsychotic efficacy. This study investigated whether baseline immune abnormalities measured with blood cell count ratios can predict the clinical response after initiating treatment with clozapine in patients with clozapine naïve TRS.

METHODS

A longitudinal design was developed, involving 32 patients diagnosed with treatment-resistant, clozapine-naïve schizophrenia-spectrum disorder. Patients were evaluated at baseline before clozapine starting and 8 weeks of follow-up. Psychopathological status and immune abnormalities (blood cell count ratios: neutrophil-lymphocyte ratio [NLR], monocyte-lymphocyte ratio [MLR], platelet-lymphocyte ratio [PLR] and basophil-lymphocyte ratio [BLR]) were evaluated in each visit.

RESULTS

Baseline NLR (b=- 0.364; p=0.041) and MLR (b =- 0.400; p=0.023) predicted the change in positive symptoms over the 8-week period. Patients who exhibited a clinical response showed higher baseline NLR (2.38±0.96 vs. 1.75±0.83; p=0.040) and MLR (0.21±0.06 vs. 0.17±0.02; p=0.044) compared to non-responders. In the ROC analysis, the threshold points to distinguish between responders and non-responders were approximately 1.62 for NLR and 0.144 for MLR, yielding AUC values of 0.714 and 0.712, respectively. No statistically significant differences were observed in the blood cell count ratios from baseline to the 8-week follow-up.

CONCLUSION

Our study emphasizes the potential clinical significance of baseline NLR and MLR levels as predictors of initial clozapine treatment response in patients with TRS. Future studies with larger sample sizes and longer follow-up periods should replicate our findings.

Evaluation of peripheral inflammatory parameters of cases with suicide attempts

PURPOSE

The purpose of the present study was to examine the inflammation markers of patients who have attempted suicide by comparing them with those of healthy controls. The leukocyte cell levels, Neutrophil/Lymphocyte Ratios (NLR), Basophil/Lymphocyte Ratios (BLR), Platelet/Lymphocyte Ratios (PLR), Monocyte/Lymphocyte Ratios (MLR), Systemic Inflammation Index (SII), Neutrophil/Albumin Ratios (NAR) values were compared with those of healthy controls.

METHOD

A total of 376 people were included in the study (276 patients who attempted suicide, and 100 healthy people (the control group)). The demographic data and laboratory parameters of the participants were analyzed from the hospital automation system.

RESULTS

The participants' female/male ratio was 158/118 (42.8%/57.1%) in the group of patients who attempted suicide and 41/59 (41/59%) in the control group. When the distribution of laboratory parameters was evaluated, although the NLR, BLR, NAR, SII, and MLR values, which are indicators of peripheral inflammation, were high in patients who attempted suicide (p = 0.049 for MLR, p = 0.000 for other values), the PLR (p = 0.586) value did not differ significantly between the groups. Patients who had attempted more than one suicide had elevated BLR (p = 0.007), SII (p = 0.003), and NAR (p = 0.003) values.

DISCUSSION

Based on the results obtained, it was considered that paying attention to inflammation parameters in patient follow-ups, and monitoring of SII, NLR, BLR, and NAR values of patients who had attempted suicide once would be beneficial in preventing future suicide attempts. These results strengthen the idea that inflammatory processes play roles in the pathophysiology of suicidal behavior. However, further studies are needed to elucidate the complex pathophysiological mechanisms of immune pathways underlying suicidal behavior.

Bidirectional two-sample Mendelian randomization study of differential white blood cell counts and schizophrenia

BACKGROUND

Schizophrenia and white blood cell counts (WBC) are both complex and polygenic traits. Previous evidence suggests that increased WBC are associated with higher all-cause mortality, and other studies have found elevated WBC in first-episode psychosis and chronic schizophrenia. However, these observational findings may be confounded by antipsychotic exposures and their effects on WBC. Mendelian randomization (MR) is a useful method for examining the directions of genetically-predicted relationships between schizophrenia and WBC.

METHODS

We performed a two-sample MR using summary statistics from genome-wide association studies (GWAS) conducted by the Psychiatric Genomics Consortium Schizophrenia Workgroup (N = 130,644) and the Blood Cell Consortium (N = 563,946). The MR methods included inverse variance weighted (IVW), MR Egger, weighted median, MR-PRESSO, contamination mixture, and a novel approach called mixture model reciprocal causal inference (MRCI). False discovery rate was employed to correct for multiple testing.

RESULTS

Multiple MR methods supported bidirectional genetically-predicted relationships between lymphocyte count and schizophrenia: IVW (b = 0.026; FDR p-value = 0.008), MR Egger (b = 0.026; FDR p-value = 0.008), weighted median (b = 0.013; FDR p-value = 0.049), and MR-PRESSO (b = 0.014; FDR p-value = 0.010) in the forward direction, and IVW (OR = 1.100; FDR p-value = 0.021), MR Egger (OR = 1.231; FDR p-value < 0.001), weighted median (OR = 1.136; FDR p-value = 0.006) and MRCI (OR = 1.260; FDR p-value = 0.026) in the reverse direction. MR Egger (OR = 1.171; FDR p-value < 0.001) and MRCI (OR = 1.154; FDR p-value = 0.026) both suggested genetically-predicted eosinophil count is associated with schizophrenia, but MR Egger (b = 0.060; FDR p-value = 0.010) and contamination mixture (b = -0.013; FDR p-value = 0.045) gave ambiguous results on whether genetically predicted liability to schizophrenia would be associated with eosinophil count. MR Egger (b = 0.044; FDR p-value = 0.010) and MR-PRESSO (b = 0.009; FDR p-value = 0.045) supported genetically predicted liability to schizophrenia is associated with elevated monocyte count, and the opposite direction was also indicated by MR Egger (OR = 1.231; FDR p-value = 0.045). Lastly, unidirectional genetic liability from schizophrenia to neutrophil count were proposed by MR-PRESSO (b = 0.011; FDR p-value = 0.028) and contamination mixture (b = 0.011; FDR p-value = 0.045) method.

CONCLUSION

This MR study utilised multiple MR methods to obtain results suggesting bidirectional genetic genetically-predicted relationships for elevated lymphocyte counts and schizophrenia risk. In addition, moderate evidence also showed bidirectional genetically-predicted relationships between schizophrenia and monocyte counts, and unidirectional effect from genetic liability for eosinophil count to schizophrenia and from genetic liability for schizophrenia to neutrophil count. The influence of schizophrenia to eosinophil count is less certain. Our findings support the role of WBC in schizophrenia and concur with the hypothesis of neuroinflammation in schizophrenia.

Inflammatory blood cells and ratios at remission for psychosis relapse prediction: A three-year follow-up of a cohort of first episodes of schizophrenia

BACKGROUND

The clinical course following a first episode of schizophrenia (FES) is often characterized by recurrent relapses, resulting in unfavorable clinical and functional outcomes. Inflammatory dysregulation has been implicated in relapse risk; however, the predictive value of inflammatory blood cells in clinically remitted patients after a FES has not been previously explored.

METHODS

In this study, we closely monitored 111 patients in remission after a FES until relapse or a three-year follow-up endpoint. The participants were recruited from the multicenter 2EPS Project. Data on inflammatory blood cells and ratios were collected at baseline and at the time of relapse or after three years of follow-up.

RESULTS

Monocyte counts (OR = 1.91; 95 % CI = 1.07-3.18; p = 0.009) and basophil counts (OR = 1.09; 95 % CI = 1.01-1.12; p = 0.005) at baseline were associated with an increased risk of relapse, while the platelet-lymphocyte ratio (OR = 0.98; 95 % CI = 0.97-0.99; p = 0.019) was identified as a protective factor. However, after adjusting for cannabis and tobacco use during the follow-up, only monocyte counts (OR = 1.73; 95 % CI = 1.03-2.29; p = 0.027) and basophil counts (OR = 1.08; 95 % CI = 1.01-1.14; p = 0.008) remained statistically significant. ROC curve analysis indicated that the optimal cut-off values for discriminating relapsers were 0.52 × 10^9/L (AUC: 0.66) for monocytes and 0.025 × 10^9/L (AUC: 0.75) for basophils. When considering baseline inflammatory levels, no significant differences were observed in the inflammatory biomarkers at the endpoint between relapsers and non-relapsers.

CONCLUSION

This study provides evidence that higher monocyte and basophil counts measured at remission after a FES are associated with an increased risk of relapse during a three-year follow-up period.

The neutrophil-lymphocyte ratio in first-episode medication-naïve patients with schizophrenia: A 12-week longitudinal follow-up study

Inflammation has been related to schizophrenia (SZ). The neutrophil-to-lymphocyte ratio (NLR) is an inexpensive inflammatory marker, however, its potential predictive value in patients with SZ has not been extensively investigated. This study aimed to examine whether NLR could predict the clinical response to antipsychotics in this population. One hundred and ninety-five medication-naïve first-episode schizophrenia (MNFES) patients were recruited and received treatment with risperidone for 12 weeks in the present study. Clinical symptoms were evaluated at week 0 and the end of 12 weeks of treatment using the PANSS scales. Complete blood counts were determined at baseline. We found that baseline NEU counts and NLR were positively associated with improvements in clinical symptoms in patients. In addition, MNFES patients with higher baseline NLR values showed a better treatment response to antipsychotics. Linear regression analysis revealed a predictive role of baseline NLR for the improvements of clinical symptoms in SZ patients. Our findings demonstrate that higher NLR was related to better improvements in symptoms after 12 weeks of treatment with antipsychotics, which renders it a promising biomarker of the response to antipsychotics in clinical practice.

Association between neutrophil to lymphocyte ratio and inflammatory biomarkers in patients with a first episode of psychosis

Neutrophil to lymphocyte ratio (NLR) has been proposed as an emerging marker of the immune system alterations in psychotic disorders. However, it is not entirely clear whether NLR elevation is a characteristic of the psychotic disorder itself, which inflammatory pathways activation is detecting, or which possible confounding variables could alter its interpretation. We aimed to analyze the relationship of NLR values with a panel of inflammatory and oxidative/nitrosative stress biomarkers and main potential confounding factors in a well-characterized cohort of 97 patients with a first episode of psychosis (FEP) and 77 matched healthy controls (HC). In the FEP group, NLR values presented a moderate, positive correlation with the pro-inflammatory mediator Prostaglandin E2 levels (r = 0.36, p < 0.001) and a small but significant, positive correlation with cannabis use (r = 0.25, p = 0.017). After controlling for cannabis use, the association between NLR and PGE2 remained significant (beta = 0.31, p = 0.012). In the HC group, NLR values negatively correlated with body mass index (BMI, r = -0.24, p = 0.035) and positively correlated with tobacco use (r = 0.25, p = 0.031). These findings support a relationship between the elevation of NLR values and an elevated expression of proinflammatory pathways related to stress response in patients with a FEP. In addition, our study highlights the importance of considering variables such as cannabis or tobacco consumption, and BMI when interpreting the results of studies aimed to establish a clinical use of NLR. These considerations may help future research to use NLR as a reliable biomarker to determine immune system status in this population.

Relationship between blood-based inflammatory indices and clinical score of schizophrenia patients: A cross-sectional study

Schizophrenia is a severe mental disorder that may involve inflammation. Inflammatory indices, such as the neutrophil to lymphocyte ratio (NLR), the monocyte to lymphocyte ratio (MLR), the platelet to lymphocyte ratio (PLR), and the systemic inflammation index (SII), are simple and inexpensive measures of inflammation that have been associated with various diseases. However, few studies have compared these indices and their relationships with clinical symptoms in schizophrenia. We conducted a cross-sectional study of 121 schizophrenia patients (101 males, 20 females). We measured the blood-based inflammatory indices (NLR, MLR, PLR, and SII) and assessed the clinical symptoms of schizophrenia using the Positive and Negative Syndrome Scale (PANSS). Statistical analyses were performed to examine the correlations and effects of the inflammatory indices on PANSS scores. We found that NLR, MLR, PLR, and SII were positively correlated with PANSS total score, PANSS positive score, PANSS negative score, and general psychopathology score (adjusted P < 0.02 for all correlations). Subgroup analysis showed that correlations between inflammatory indices and the clinical scores differed by gender. In males, all inflammatory indices were positively correlated with all clinical scores. On the other hand, in females, only NLR and SII were positively correlated with all clinical scores. After adjusting for confounders, we also found that NLR was a predictor of PANSS total score (β = 23, adjusted P < 0.02), PANSS positive score (β = 2.6, adjusted P = 0.03), PANSS negative score (β = 6.8, adjusted P < 0.02), and PANSS general psychopathology score (β = 13.6, adjusted P < 0.02), while SII was only a predictor for PANSS total score (β = -0.00003, adjusted P = 0.01) and general psychopathology scores (β = -0.00002, adjusted P < 0.02). These findings suggest that inflammation is involved in the pathophysiology and clinical manifestations of schizophrenia, and that blood-based inflammatory indices may serve as screening tools or indicators for the inflammatory status and severity of symptoms of schizophrenia patients.

Hematological and inflammatory markers in Han Chinese patients with drug-free schizophrenia: relationship with symptom severity

Background

There is a growing amount of evidence suggesting that immunity and inflammation play an important role in the pathophysiology of schizophrenia. In this study, we aimed to examine the relationship between hematological and inflammatory markers with symptom severity in Han Chinese patients with drug-free schizophrenia.

Methods

This retrospective study was conducted at Chaohu Hospital of Anhui Medical University and data were extracted from the electronic medical record system over a 5-year period (May 2017 to April 2022), including participants' general and clinical information as well as Brief Psychiatric Rating Scale (BPRS) scores and hematological parameters.

Results

A total of 2,899 patients with schizophrenia were identified through the initial search. After screening, 91 patients and 141 healthy controls (HCs) were included. The patients had a higher value of neutrophils/lymphocytes ratio (NLR), monocyte/lymphocyte ratio (MLR), and platelet/lymphocyte ratio (PLR) than HCs (all P < 0.001). MLR was positively correlated with BPRS total score (r = 0.337, P = 0.001) and resistance subscale score (r = 0.350, P = 0.001). Binary logistic regression analyses revealed that severely ill was significantly associated with being male and a higher value of MLR (Natural Logaruthm, Ln) (all P < 0.05), and the receiver operating characteristic (ROC) analysis showed good performance of a regression model with an area under the curve (AUC) value of 0.787.

Conclusion

Patients with drug-free schizophrenia have an unbalanced distribution of peripheral blood granulocytes, and elevated NLR, MLR and PLR. Patients with higher value of MLR tend to have more psychotic symptoms, especially those symptoms of hostility, uncooperativeness, and suspiciousness. Our study gives a preliminary indication that MLR is a potential predictor of disease severity in patients with drug-free schizophrenia.

Neutrophil-Lymphocyte Ratio in Patients With Acute Schizophrenia

Introduction Schizophrenia symptom severity is linked to neuroinflammation. Certain blood cell indexes such as neutrophil-lymphocyte ratio (NLR) and neutrophil-albumin ratio (NAR) have been used as biomarkers in various diseases, including schizophrenia. In acute clinical practice, it is challenging to decide whether to provide intravenous antipsychotic treatment in some cases due to the lack of objective biomarkers of psychiatric symptoms. The NLR of individuals with schizophrenia is thought to be associated with disease severity, and changes in NLR may reflect a patient's response to antipsychotic treatment. We investigated the application of NLR as a biomarker for identifying acute severity and determining acute treatment response in patients with schizophrenia. Methods We retrospectively examined 251 inpatients diagnosed with schizophrenia and classified them according to treatment (intravenous haloperidol vs. oral antipsychotic medication during the acute phase) and investigated their NLR and NAR while receiving inpatient care. Results A total of 48 inpatients were given intravenous haloperidol to manage their acute symptoms; 208 were given oral antipsychotics. The intravenous haloperidol group experienced more severe symptoms, such as agitation and disorganized thinking, during the acute phase. Further, those who received intravenous haloperidol had significantly higher Clinical Global Impression-Severity (CGI-S) scores than the oral antipsychotic group. NLR and NAR were also significantly higher in the haloperidol intravenous group. Conclusion Elevated NLR and NAR could be easily measured in patients with psychomotor agitation who should be treated at any facility. Further, they are useful biomarkers for determining disease severity and the effects of treatment on psychomotor excitement in patients who require intravenous haloperidol.

Catatonia-like behavior and immune activation: a crosstalk between psychopathology and pathology in schizophrenia

BACKGROUND

In Kalhbaum's first characterization of catatonia, the emotional symptoms, such as decreased or restricted expression of feelings and emotions, which is described as blunted affect, are related to the motor symptoms. In later years, the affective domain was excluded from the concept of catatonia and was not included among the diagnostic criteria in the various Diagnostic Statistical Manual (DSM) versions. In recent times, some authors have proposed the proposition of reevaluating the notion of catatonia through the reintroduction of the affective domain. The objective of this study was to examine the correlation between catatonic-like behavior (CLB), such as emotional withdrawal, blunted affect, and psychomotor slowing, and inflammatory markers, namely the neutrophil/lymphocytes ratio (NLR) and lymphocytes/monocytes ratio (LMR), in individuals diagnosed with schizophrenia.

METHOD

A sample of 25 patients with schizophrenia (10 females, 15 males) was recruited, and the Brief Psychiatric Rating Scale (BPRS) was used to assess the severity of emotional withdrawal, blunted affect, and psychomotor slowing.

FINDINGS

The correlation analysis (Spearman ρ) revealed a robust direct association between blunted affect and psychomotor slowing (ρ = 0.79, P = 0.001), and a significant direct correlation between CLB (emotional withdrawal, ρ = 0.51, P = 0.05; blunted affect ρ = 0.58, P = 0.05; motor retardation, ρ = 0.56, P = 0.05) and LMR (ρ = 0.53, P = 0.05). In addition, patients with a duration of illness (DOI) older than five years had a higher presence of CLB and a higher LMR than patients with a more recent diagnosis of the disease. Likely, patients with positive symptoms and in the prodromal and active stages of the disease have a different immune profile than patients in the residual stage and with a predominance of negative symptoms.

CONCLUSIONS

Psychomotor slowing and blunted affect are two significantly related features, representing the two-faced Janus of immobility. Furthermore, aggregating them in CLB is more predominant the longer the duration of schizophrenia and is associated with different a specific pattern of immune activation.

Correlation between C-reactive protein and the inflammatory ratios in acute schizophrenia inpatients: are they associated?

C-reactive protein (CRP) and inflammatory ratios have been proposed to study immune dysregulation in schizophrenia. Nevertheless, links between CRP and inflammatory ratios in acute SCZ inpatients have been understudied. This study investigated the relationship between CRP and inflammatory ratios (Neutrophil-Lymphocyte Ratio [NRL], Platelet-Lymphocyte Ratio [PLR], Monocyte-Lymphocyte ratio [MLR] and Basophil-Lymphocyte Ratio [BLR]) in a total of 698 acute SCZ inpatients; and analysed how this relationship is affected by sex and type of episode. CRP correlated with NLR (rs = 0.338, p < 0.001), PLR (rs = 0.271, p < 0.001) and MLR (rs = 0.148, p < 0.001) but not with BLR (rs = 0.059, p = 0.121). Multiple lineal regression analysis showed that high levels of NLR, MLR and PLR but not BLR were independently associated with high CRP levels. No sex-related variations were found. Significant associations were maintained for NLR and MLR in first-episode and multiepisode SCZ, although the strength of the association was stronger in multiepisode SCZ. Again, no sex-related differences were found in these associations. In conclusion, inflammatory ratios were low to moderately associated with CRP in acute SCZ inpatients. NLR and multiepisode SCZ showed the highest associations with CRP. Future studies should consider inflammatory ratios not as a substitute for CRP but as a complementary biomarker.

Microglia and Other Cellular Mediators of Immunological Dysfunction in Schizophrenia: A Narrative Synthesis of Clinical Findings

Schizophrenia is a complex psychiatric condition that may involve immune system dysregulation. Since most putative disease mechanisms in schizophrenia have been derived from genetic association studies and fluid-based molecular analyses, this review aims to summarize the emerging evidence on clinical correlates to immune system dysfunction in this psychiatric disorder. We conclude this review by attempting to develop a unifying hypothesis regarding the relative contributions of microglia and various immune cell populations to the development of schizophrenia. This may provide important translational insights that can become useful for addressing the multifaceted clinical presentation of schizophrenia.

Immune System and Brain/Intestinal Barrier Functions in Psychiatric Diseases: Is Sphingosine-1-Phosphate at the Helm?

Over the past few decades, extensive research has shed light on immune alterations and the significance of dysfunctional biological barriers in psychiatric disorders. The leaky gut phenomenon, intimately linked to the integrity of both brain and intestinal barriers, may play a crucial role in the origin of peripheral and central inflammation in these pathologies. Sphingosine-1-phosphate (S1P) is a bioactive lipid that regulates both the immune response and the permeability of biological barriers. Notably, S1P-based drugs, such as fingolimod and ozanimod, have received approval for treating multiple sclerosis, an autoimmune disease of the central nervous system (CNS), and ulcerative colitis, an inflammatory condition of the colon, respectively. Although the precise mechanisms of action are still under investigation, the effectiveness of S1P-based drugs in treating these pathologies sparks a debate on extending their use in psychiatry. This comprehensive review aims to delve into the molecular mechanisms through which S1P modulates the immune system and brain/intestinal barrier functions. Furthermore, it will specifically focus on psychiatric diseases, with the primary objective of uncovering the potential of innovative therapies based on S1P signaling.

High blood levels of brain-derived neurotrophic factor (BDNF) mRNA in early psychosis are associated with inflammatory markers

The brain-derived neurotrophic factor (BDNF) single nucleotide polymorphism (SNP) rs6265C > T, Val66Met, affects BDNF secretion and has been related to inflammatory processes. Both the rs6265 and BDNF protein levels have been widely investigated in neuropsychiatric disorders with conflicting results. In the present study we examined BDNF mRNA expression in blood considering the SNP rs6265 and its relationship with inflammatory markers in the early stages of psychosis. The rs6265 genotype and blood BDNF mRNA levels were measured in 34 at-risk mental states (ARMS) individuals, 37 patients with first-episode psychosis (FEP) and 42 healthy controls (HCs) by quantitative PCR and reverse transcription (RT)-qPCR using validated TaqMan assays. We also obtained measures of interleukin-6 (IL6) mRNA levels, fibrinogen, neutrophil-to-lymphocyte ratio (NLR) and high-sensitivity C-reactive protein. We identified that BDNF mRNA levels were associated with the rs6265 genotype in an allele-dose-dependent manner, with low expression levels associated with the T allele (Met substitution). Thus, we controlled for the rs6265 genotype in all analyses. Blood BDNF mRNA levels differed between diagnostic groups: patients with FEP exhibited higher blood BDNF mRNA levels than ARMS individuals, and the lowest levels were observed in HC. In addition, we observed significant correlations between BDNF mRNA levels and inflammatory markers (IL6 mRNA levels and NLR), controlled by the rs6265 genotype, in ARMS and FEP groups. This exploratory study suggests that the rs6265 genotype is associated with differential blood mRNA expression of BDNF that increases with illness progression and correlated with inflammation in the early stages of psychosis.

Differences in white blood cell proportions between schizophrenia cases and controls are influenced by medication and variations in time of day

Cases with schizophrenia (SCZ) and healthy controls show differences in white blood cell (WBC) counts and blood inflammation markers. Here, we investigate whether time of blood draw and treatment with psychiatric medications are related to differences in estimated WBC proportions between SCZ cases and controls. DNA methylation data from whole blood was used to estimate proportions of six subtypes of WBCs in SCZ patients (n = 333) and healthy controls (n = 396). We tested the association of case-control status with estimated cell-type proportions and the neutrophil-to-lymphocyte ratio (NLR) in 4 models: with/without adjusting for time of blood draw, and then compared results from blood samples drawn during a 12-h (07:00-19:00) or 7-h (07:00-14:00) period. We also investigated WBC proportions in a subgroup of medication-free patients (n = 51). Neutrophil proportions were significantly higher in SCZ cases (mean=54.1%) vs. controls (mean=51.1%; p = <0.001), and CD8⁺T lymphocyte proportions were lower in SCZ cases (mean=12.1%) vs. controls (mean=13.2%; p = 0.001). The effect sizes in the 12-h sample (07:00-19:00) showed a significant difference between SCZ vs. controls for neutrophils, CD4⁺T, CD8⁺T, and B-cells, which remained significant after adjusting for time of blood draw. In the samples matched for time of blood draw during 07.00-14.00, we also observed an association with neutrophils, CD4⁺T, CD8⁺T, and B-cells that was unaffected by further adjustment for time of blood draw. In the medication-free patients, we observed differences that remained significant in neutrophils (p = 0.01) and CD4⁺T (p = 0.01) after adjusting for time of day. The association of SCZ with NLR was significant in all models (range: p < 0.001 to p = 0.03) in both medicated and unmedicated patients. In conclusion, controlling for pharmacological treatment and circadian cycling of WBC is necessary for unbiased estimates in case-control studies. Nevertheless, the association of WBC with SCZ remains, even after adjusting for the time of day.

Increased blood neutrophil extracellular traps (NETs) associated with early life stress: translational findings in recent-onset schizophrenia and rodent model

Higher levels of interleukin (IL)-6 and elevated neutrophil counts are consistently reported in the blood of patients with schizophrenia. Stressors during childhood and/or adolescence are major socioenvironmental risk factors for schizophrenia and may contribute to immune dysregulation. Previous studies using blood cytokines to stratify patients with schizophrenia suggest that only a subset presents a low-grade inflammatory state. However, these studies have not addressed whether environmental factors such as childhood maltreatment contributed to identifying inflammatory clusters. Moreover, a neutrophil-related mechanism (Neutrophil Extracellular Traps; NETs) central to both the initiation and chronicity of autoimmune and inflammatory diseases has never been investigated in psychiatry. Elevated NETs in schizophrenia may predispose patients to inflammatory and autoimmune diseases resulting in reduced life expectancy. We, therefore, investigated NETs as a novel mechanism and biological target in early schizophrenia and their role together with IL-6 and childhood maltreatment in identifying cluster subgroups. We found increased NETs in the plasma of patients with early schizophrenia (n = 78) compared to both their unaffected siblings (n = 25) and community controls (n = 78), irrespective of sex, body mass index, psychoactive drug use, or tobacco smoking. Increased NETs in patients were unrelated to antipsychotic treatment, which was further tested in vitro using fresh neutrophils. By applying unsupervised two-step clustering analysis, we integrated values of NETs, IL-6, and childhood maltreatment scores. We identified two main clusters; childhood maltreatment scores and NETs were the most important variables contributing to cluster separation (high-CL1 and low-CL2), while IL-6 was the least contributor. Patients allocated in the high-CL1 (61.5%) had significantly higher childhood maltreatment scores, NETs, and IL-6 levels than the remaining groups (patients low-CL2, siblings, and controls high-CL1 and low-CL2). We complemented these findings with a rat model based on stress exposure during adolescence that results in several schizophrenia-like changes in adulthood. We found that adolescent stressed rats had higher NETs and IL-6 levels in serum compared to non-stressed rats with a tendency to produce more NETs from the bone marrow. Altogether, this study brings a novel cellular-based mechanism in schizophrenia that, combined with early-stress, could be useful to identify subgroups for more personalised treatments.