Neutrophil CD64 for monitoring the activity of nontuberculous mycobacteria infection in patients with rheumatoid arthritis

Transmigration of Neutrophils From Patients With Familial Mediterranean Fever Causes Increased Cell Activation

Familial Mediterranean fever (FMF) is caused by pyrin-encoding MEFV gene mutations and characterized by the self-limiting periods of intense inflammation, which are mainly mediated by a massive influx of polymorphonuclear neutrophils (PMNs) into the inflamed sites. Perturbation of actin polymerization by different pathogens was shown to activate the pyrin inflammasome. Our aim was to test whether cytoskeletal dynamics in the absence of pathogens may cause abnormal activation of PMNs from FMF patients. We also aimed to characterize immunophenotypes of circulating neutrophils and their functional activity. Circulating PMNs displayed heterogeneity in terms of cell size, granularity and immunophenotypes. Particularly, PMNs from the patients in acute flares (FMF-A) exhibited a characteristic of aged/activated cells (small cell size and granularity, up-regulated CXCR4), while PMNs form the patients in remission period (FMF-R) displayed mixed fresh/aged cell characteristics (normal cell size and granularity, up-regulated CD11b, CD49d, CXCR4, and CD62L). The findings may suggest that sterile tissue-infiltrated PMNs undergo reverse migration back to bone marrow and may explain why these PMNs do not cause immune-mediated tissue damage. A multidirectional expression of FcγRs on neutrophils during acute flares was also noteworthy: up-regulation of FcγRI and down-regulation of FcγRII/FcγRIII. We also observed spontaneous and fMPL-induced activation of PMNs from the patients after transmigration through inserts as seen by the increased expression of CD11b and intracellular expression of IL-1β. Our study suggests heightened sensitivity of mutated pyrin inflammasome towards cytoskeletal modifications in the absence of pathogens.

Tuberculosis comorbidity with rheumatoid arthritis: Gene signatures, associated biomarkers, and screening

Rheumatoid arthritis (RA) is known to be related to an elevated risk of infections because of its pathobiology and the use of immunosuppressive therapies. Reactivation of latent tuberculosis (TB) infection is a serious issue in patients with RA, especially after receiving anti-TNFs therapy. TNF blocking reinforces the TB granuloma formation and maintenance and the growth of Mycobacterium tuberculosis (Mtb). After intercurrent of TB infection, the standard recommendation is that the treatment with TNF inhibitors to be withheld despite its impressive effect on suppression of inflammation until the infection has resolved. Knowing pathways and mechanisms that are common between two diseases might help to find the mechanistic basis of this comorbidity, as well as provide us a new approach to apply them as therapeutic targets or diagnostic biomarkers. Also, screening for latent TB before initiation of an anti-TNF therapy can minimize complications. This review summarizes the shared gene signature between TB and RA and discusses the biomarkers for early detection of this infection, and screening procedures as well.

Neutrophil CD64 expression levels in IGRA-positive individuals distinguish latent tuberculosis from active disease

BACKGROUND

CD64 (FcγR1) is a high-affinity receptor for monomeric IgG1 and IgG3. Circulating neutrophils express very low amounts of CD64 on their surface.

OBJECTIVES

Our primary aim was to investigate the utility of neutrophil CD64 surface expression as a biomarker of active pulmonary tuberculosis (TB). We hypothesised that elevated neutrophil CD64 expression in TB infection would be associated with interferon gamma (IFN-γ) as an inducer of CD64 expression.

METHODS

The expression level of CD64 per neutrophil (PMN CD64 index) was quantitatively measured with flow cytometry using a Leuko64 kit in samples from patients with TB and latent TB infection (LTBI) as well as healthy controls, as part of a prospective cohort study in Brazil.

FINDINGS

The PMN CD64 index in patients with TB was higher than that in healthy controls and LTBI. Receiver operating characteristic curve analyses determined that the PMN CD64 index could discriminate patients with TB from those with LTBI and healthy individuals. PMN CD64 index levels returned to baseline levels after treatment.

CONCLUSIONS

The positive regulation of CD64 expression in circulating neutrophils of patients with active TB could represent an additional biomarker for diagnosis of active TB and could be used for monitoring individuals with LTBI before progression of TB disease.

Utility of CD64 on Neutrophils in Orthopedic Infection

Background

Musculoskeletal infections are often seen in the daily practice of orthopedics. Several markers [white blood cell (WBC), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), procalcitonin (PCT)] have been used for diagnosing these infections. However, these markers may be elevated due to surgery or trauma, and may not be infection-related. These markers also show drug-dependent dynamics during infection that differ from its usual dynamics. Such situations make diagnosis of infections difficult, and Cluster of Differentiation 64 (CD64) has been brought to attention. This study aimed to clarify the utility of CD64 on neutrophils by comparing it with conventional infection markers (CRP, PCT) in musculoskeletal infection.

Methods

Forty-four patients who were suspected of having musculoskeletal infection between May 2010 and November 2013 in our hospital were enrolled in this study. Patients were divided into subgroups according to their culture results, antibiotics administration, measurement timing, and if they were immunocompromised. The measurements of the infection markers were compared between each group. In addition, the positive rates of each infection marker were compared between groups.

Results

There was no difference in the infection marker measurements between several groups. There was no statistically significant difference between groups for the positive rates of CD64, CRP, and PCT.

Conclusion

We evaluated the utility of CD64 on neutrophils in musculoskeletal infection. CD64 showed the utility that was equivalent to conventional infection markers in diagnoses of various musculoskeletal infections.

Expression of CD64 on Circulating Neutrophils Favoring Systemic Inflammatory Status in Erythema Nodosum Leprosum

Erythema Nodosum Leprosum (ENL) is an immune reaction in leprosy that aggravates the patient´s clinical condition. ENL presents systemic symptoms of an acute infectious syndrome with high leukocytosis and intense malaise clinically similar to sepsis. The treatment of ENL patients requires immunosuppression and thus needs to be early and efficient to prevent both disabilities and permanent nerve damage. Some patients experience multiple episodes of ENL and prolonged use of immunosuppressive drugs may lead to serious adverse effects. Thalidomide treatment is extremely effective at ameliorating ENL symptoms. Several mechanisms have been proposed to explain the efficacy of thalidomide in ENL, including the inhibition of TNF production. Given its teratogenicity, thalidomide is prohibitive for women of childbearing age. A rational search for molecular targets during ENL episodes is essential to better understand the disease mechanisms involved, which may also lead to the discovery of new drugs and diagnostic tests. Previous studies have demonstrated that IFN-γ and GM-CSF, involved in the induction of CD64 expression, increase during ENL. The aim of the present study was to investigate CD64 expression during ENL and whether thalidomide treatment modulated its expression. Leprosy patients were allocated to one of five groups: (1) Lepromatous leprosy, (2) Borderline leprosy, (3) Reversal reaction, (4) ENL, and (5) ENL 7 days after thalidomide treatment. The present study demonstrated that CD64 mRNA and protein were expressed in ENL lesions and that thalidomide treatment reduced CD64 expression and neutrophil infiltrates-a hallmark of ENL. We also showed that ENL blood neutrophils exclusively expressed CD64 on the cell surface and that thalidomide diminished overall expression. Patient classification based on clinical symptoms found that severe ENL presented high levels of neutrophil CD64. Collectively, these data revealed that ENL neutrophils express CD64, presumably contributing to the immunopathogenesis of the disease.

[Analysis of Cases with Elevated Blood (1->3)-β-D-glucan in Relation to an Infection Marker, Neutrophil CD64 Expression]

(1->3)-β-D-glucan (BDG) is a constituent of the fungal cell wall and its blood level is known as a marker of fungal infection including pneumocystis pneumonia (PCP). Meanwhile, peripheral blood neutrophil CD64 expression (CD64) is upregulated in various infections. We analyzed patients with positive BDG (cut off 11.0 pg/mL) and those whose CD64 was measured simultaneously. In patients who visited our hospital from 2005 to 2011, BDG was measured in 3,960 samples. The number of positive samples were 441 obtained from 185 patients. In patients with positive BDG, the initial BDG was 24.3 [16.4-70.5] pg/mL (median [interquartile range]). Positive BDG samples were derived mainly from the department of Rheumatology or that of Allergy and Respirology. Common primary diseases were rheumatoid arthritis (RA) or other connective tissue diseases, followed by malignancy, none (only abnormal chest X-ray) and bronchial asthma. The rates of afebrile patients, patients on immunosuppressive therapy and those with a normal range of white blood cell count were 63.7%, 50.9% and 40.8%, respectively. The main causes of positive BDG were PCP (n = 38, 20.5%) and non-PCP mycosis (n = 48, 25.9%, including 26 cases of aspergillosis). Others (99 patients, 53.6%) had positive BDG of unknown origin and 53 of them ameliorated spontaneously, most of whom could have been examples of pseudo-positive BDG. The number of deceased patients was 57 (30.8%) consisting of 9 PCP, 16 non-PCP mycosis and others. The median initial positive BDG levels in patients with PCP, non-PCP mycosis and others were 49.9, 28.9 and 19.7pg/mL, respectively. The positive rate of CD64 (cut off 2,000 molecules/cell) measured simultaneously with initial positive BDG was 77.8%. In RA patients with PCP, 94.7% of them had positive CD64 and the levels of CD64 were significantly higher than those in RA patients with bacterial pneumonia (median 9,386 vs 4,399 molecules/cell) in that same period. The positive rate of CD64 was lower in patients with positive BDG of unknown origin than those with PCP or non-PCP mycosis, which implies positive CD64 can exclude pseudo-positive BDG. Immunosuppressed patients often exhibit positive BDG. Simultaneous measurement of BDG and CD64, a quick pan-infection marker, assists the decision whether the positive BDG is true or false-positive.