The treatment for
cocaine use constitutes a clinical challenge because of the lack of appropriate
therapies and the high rate of relapse. Recent evidence indicates that the immune system might be involved in the pathogenesis of
cocaine addiction and its co-morbid
psychiatric disorders. This work examined the plasma pro-inflammatory
cytokine and
chemokine profile in abstinent
cocaine users (n = 82) who sought outpatient
cocaine treatment and age/sex/body mass-matched controls (n = 65). Participants were assessed with the diagnostic interview Psychiatric Research Interview for Substance and Mental Diseases according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR).
Tumor necrosis factor-alpha,
chemokine (C-C motif) ligand 2/
monocyte chemotactic protein-1 and
chemokine (C-X-C motif) ligand 12 (CXCL12)/stromal cell-derived factor-1 (SDF-1) were decreased in
cocaine users, although all
cytokines were identified as predictors of a lifetime pathological use of
cocaine.
Interleukin-1 beta (IL-1β),
chemokine (C-X3-C motif) ligand 1 (CX3CL1)/
fractalkine and CXCL12/SDF-1 positively correlated with the
cocaine symptom severity when using the DSM-IV-TR criteria for
cocaine abuse/dependence. These
cytokines allowed the categorization of the outpatients into subgroups according to severity, identifying a subgroup of severe
cocaine users (9-11 criteria) with increased prevalence of co-morbid
psychiatric disorders [mood (54%), anxiety (32%), psychotic (30%) and personality (60%) disorders]. IL-1β was observed to be increased in users with such
psychiatric disorders relative to those users with no diagnosis. In addition to these clinical data, studies in mice demonstrated that plasma IL-1β, CX3CL1 and CXCL12 were also affected after acute and chronic
cocaine administration, providing a preclinical model for further research. In conclusion,
cocaine exposure modifies the circulating levels of pro-inflammatory mediators. Plasma
cytokine/
chemokine monitoring could improve the stratification of
cocaine consumers seeking treatment and thus facilitate the application of appropriate interventions, including management of heightened risk of psychiatric co-morbidity. Further research is necessary to elucidate the role of the immune system in the etiology of
cocaine addiction.