Cytokines in human leptospirosis

The other great imitator among infectious diseases: Leptospirosis

INTRODUCTION

Leptospirosis is a worldwide zoonosis responsible for highly diverse clinical presentations with a wide range of severity. Variable environment exposures to infected urines of rodents have been described.

OBSERVATION

We report five cases of serologically confirmed leptospirosis leading to hospitalization in an intensive care unit (ICU) of a French center. These patients displayed neurological, respiratory, and abdominal presentation of leptospirosis with variable level of severity. Either professional, leisure related, or daily living exposures have been retrieved.

CONCLUSION

These cases underline the diversity of clinical presentation and environmental exposure of this infectious disease. They highlight the interest of an exhaustive anamnesis with collection of professional activity, environmental exposures, and leisure activities.

Human leptospirosis: In search for a better vaccine

Leptospirosis is a neglected disease caused by bacteria of the genus Leptospira and is more prevalent in tropical and subtropical countries. This pathogen infects humans and other animals, responsible for the most widespread zoonosis in the world, estimated to be responsible for 60 000 deaths and 1 million cases per year. To date, commercial vaccines against human leptospirosis are available only in some countries such as Japan, China, Cuba and France. These vaccines prepared with inactivated Leptospira (bacterins) induce a short-term and serovar-specific immune response, with strong adverse side effects. To circumvent these limitations, several research groups are investigating new experimental vaccines in order to ensure that they are safe, efficient, and protect against several pathogenic Leptospira serovars, inducing sterilizing immunity. Most of these protocols use attenuated cultures, preparations after LPS removal, recombinant proteins or DNA from pathogenic Leptospira spp. The aim of this review was to highlight several promising vaccine candidates, considering their immunogenicity, presence in different pathogenic Leptospira serovars, their role in virulence or immune evasion and other factors.

Leptospira interrogans Prevents Macrophage Cell Death and Pyroptotic IL-1β Release through Its Atypical Lipopolysaccharide

Leptospira interrogans are bacteria that can infect all vertebrates and are responsible for leptospirosis, a neglected zoonosis. Some hosts, such as humans, are susceptible to the disease, whereas mice are resistant and get chronically colonized. Although leptospires escape recognition by some immune receptors, they activate the NOD-like receptor pyrin 3-inflammasome and trigger IL-1β secretion. Classically, IL-1β secretion is associated with lytic inflammatory cell death called pyroptosis, resulting from cytosolic LPS binding to inflammatory caspases, such as caspase 11. Interestingly, we showed that L. interrogans and Leptospira biflexa do not trigger cell death in either murine, human, hamster, or bovine macrophages, escaping both pyroptosis and apoptosis. We showed, in murine cells, that the mild IL-1β secretion induced by leptospires occurred through nonlytic caspase 8-dependent gasdermin D pore formation and not through activation of caspase 11/noncanonical inflammasome. Strikingly, we demonstrated a potent antagonistic effect of pathogenic L. interrogans and their atypical LPS on spontaneous and Escherichia coli LPS-induced cell death. Indeed, LPS of L. interrogans efficiently prevents caspase 11 dimerization and subsequent massive gasdermin D cleavage. Finally, we showed that pyroptosis escape by leptospires prevents massive IL-1β release, and we consistently found no major role of IL-1R in controlling experimental leptospirosis in vivo. Overall, to our knowledge, our findings described a novel mechanism by which leptospires dampen inflammation, thus potentially contributing to their stealthiness.

Clinical spectrum of endemic leptospirosis in relation to cytokine response

OBJECTIVES

To describe the clinical spectrum and the cytokine response of leptospirosis patients in an endemic setting of Sri Lanka.

METHODS

Patients presenting to the university teaching hospital, Anuradhapura, Sri Lanka with a leptospirosis-compatible illness were recruited over a period of 12 months starting from June 2012. Daily clinical and biochemical parameters of the patients were prospectively assessed with a follow-up of 14 days after discharge. A magnetic bead-based multiplex cytokine kit was used to detect 17 cytokines.

RESULTS

Of the 142 clinically suspected leptospirosis patients recruited, 47 were confirmed and, 29 cases were labeled as "probable." Thrombocytopenia and leukocytosis were observed at least once during the hospital stay among 76(54%) and 39(28%) patients, respectively. Acute kidney injury was observed in 31 patients (22%) and it was significantly higher among confirmed and probable cases. Hu TNF-α and IL-1β were detected only in patients without complications. Hu MIP-1b levels were significantly higher among patients with complications. During the convalescence period, all tested serum cytokine levels were lower compared to the acute sample, except for IL-8. The cytokine response during the acute phase clustered in four different groups. High serum creatinine was associated GM-CSF, high IL-5 and IL-6 level were correlates with lung involvement and saturation drop. The patients with high billirubin (direct)>7 mmol/l had high IL-13 levels.

CONCLUSIONS

Results of this study confirms that the knowledge on cytokine response in leptospirosis could be more complex than other similar tropical disease, and biosignatures that provide diagnostic and prognostic information for human leptospirosis remain to be discovered.

Contributing role of TNF, IL-10, sTNFR1 and TNF gene polymorphisms in disease severity of leptospirosis

The immune response is hypothesized as an important factor in the disease outcome of leptospirosis. Exaggerated immune response may promote tissue damage that lead to severe disease outcome. In this study TNF, IL-10, sTNFR1 levels were measured among sixty-two hospitalized leptospirosis confirmed patients in Sri Lanka. Thirty-one serum samples from healthy individuals were obtained as controls. PCR-RFLP method was used to identify TNF gene polymorphisms and to determine their association with TNF expression and disease severity in leptospirosis. TNF (p = 0.0022) and IL-10 (p < 0.0001) were found to be significantly elevated in leptospirosis patients, while sTNFR1 (p < 0.0001) was significantly suppressed. TNF was not significantly elevated in patients with complications while the anti-inflammatory cytokine IL-10 was significantly elevated among patients with complications (p = 0.0011) and with mortality (p = 0.0088). The ratio of IL-10 to TNF was higher among patients with complications (p = 0.0008) and in fatal cases (p = 0.0179). No association between TNF gene polymorphisms and TNF expression was detected due to the low frequency of heterozygous and mutated genes present in this study population. Thus the findings of the study show that elevated levels of IL-10 in the acute phase of disease could lead to severe outcomes and a high IL-10/TNF ratio is observed in patients with complications due to leptospirosis.

The role of leptospiremia and specific immune response in severe leptospirosis

Leptospirosis can cause a high mortality rate, especially in severe cases. This multicenter cross-sectional study aimed to examine both host and pathogen factors that might contribute to the disease severity. A total of 217 leptospirosis patients were recruited and divided into two groups of non-severe and severe. Severe leptospirosis was defined by a modified sequential organ failure assessment (mSOFA) score of more than two or needed for mechanical ventilation support or had pulmonary hemorrhage or death. We found that leptospiremia, plasma neutrophil gelatinase-associated lipocalin (pNGAL), and interleukin 6 (IL-6) at the first day of enrollment (day 1) and microscopic agglutination test (MAT) titer at 7 days after enrollment (days 7) were significantly higher in the severe group than in the non-severe group. After adjustment for age, gender, and the days of fever, there were statistically significant associations of baseline leptospiremia level (OR 1.70, 95% CI 1.23–2.34, p = 0.001), pNGAL (OR 9.46, 95% CI 4.20–21.33, p < 0.001), and IL-6 (OR 2.82, 95% CI 1.96–4.07, p < 0.001) with the severity. In conclusion, a high leptospiremia, pNGAL, and IL-6 level at baseline were associated with severe leptospirosis.

Association of markers of endothelial activation and dysfunction with occurrence and outcome of pulmonary hemorrhage in dogs with leptospirosis

Background

Endothelial dysfunction might contribute to the development of leptospiral pulmonary hemorrhage syndrome (LPHS).

Hypothesis

Serum concentrations of markers of endothelial activation and dysfunction are higher in dogs with leptospirosis and correlate with the occurrence of LPHS and a higher case fatality rate.

Animals

Clinically healthy dogs (n = 31; 10/31 dogs confirmed healthy based on no detected abnormalities on blood work), dogs with leptospirosis with LPHS (n = 17) and without LPHS (n = 15), dogs with acute kidney injury not due to leptospirosis (AKI‐nL, n = 34).

Methods

Observational study. Serum concentrations of soluble intercellular adhesion molecule 1 (sICAM‐1), vascular endothelial growth factor (VEGF), and angiopoietin‐2 (Ang‐2) at admission were compared between groups. Correlations with outcome and the accuracy to predict LPHS were examined.

Results

Soluble intercellular adhesion molecule (sICAM‐1), VEGF, and Ang‐2 concentrations were higher in dogs with AKI‐nL (sICAM‐1 34.7 ng/mL, interquartile range [IQR] = 24.4‐75.5; VEGF 43.1 pg/mL, IQR = 12.3‐79.2; Ang‐2 8.5 ng/mL, IQR = 6.2‐12.3), leptospirosis without LPHS (sICAM‐1 45.1 ng/mL, IQR = 30.6‐59.0; VEGF 32.4 pg/mL, IQR = 12.5‐62.6; Ang‐2 9.6 ng/mL, IQR = 6.9‐19.3), and LPHS (sICAM‐1 69.7 ng/mL, IQR = 42.1‐89.1; VEGF 51.8 pg/mL, IQR = 26.3‐96.7; Ang‐2 8.0 ng/mL, IQR = 5.6‐12.2) compared to controls (P < .001). In dogs with leptospirosis, VEGF and sICAM‐1 were higher in nonsurvivors (sICAM‐1 89.4 ng/mL, IQR = 76.5‐101.0; VEGF 117.0 pg/mL, IQR = 90.3‐232.4) than survivors (P = .004) and sICAM‐1 predicted the development of LPHS.

Conclusions

Soluble intercellular adhesion molecule 1, VEGF, and Ang‐2 do not discriminate leptospirosis from AKI‐nL. In dogs with leptospirosis, sICAM‐1 and VEGF predict outcome and sICAM‐1 might identify dogs at risk for LPHS.

Cytokine response in human leptospirosis with different clinical outcomes: a systematic review

Background

Leptospirosis is a neglected zoonotic disease which is a major challenge for clinicians and public health professionals in tropical countries. The cytokine storm during the second (immune) phase is thought to be a major contributory factor for the leptospirosis disease severity. We aim to summarize evidence for cytokine response in leptospirosis at different clinical outcomes.

Methods

A systematic review was carried out to examine the cytokine response in leptospirosis patients using relevant scientific databases. Reference lists of the selected articles were also screened. Quality of the selected studies was assessed by using the National Institutes of Health Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies.

Results

Of the 239 articles retrieved in the initial search, 18 studies fulfilled the selection criteria. India and Thailand have produced the highest number of studies (17% each, n = 3). The majority were comparative cross-sectional studies (72%, n = 13). Overall the quality of the selected studies was fair regardless of few drawbacks such as reporting of sample size and the lack of adjustment for confounders. Microscopic agglutination test (67% - 12/18) and enzyme-linked immunosorbent assay (50% - 9/18) were commonly used for the confirmation of leptospirosis and the measurement of cytokines respectively. IL-1b, IL-2, IL-4, IL-6, IL-8, IL-10 and TNF-α levels were found to be significantly higher in severe than in mild leptospirosis. There were equivocal findings on the association between IL-1β, TNF-α and IL-10/TNF-α ratio and disease severity.

Conclusions

Leptospirosis had a wide-range of elevated cytokines. However, prospective studies in-relation to the onset of the symptom are required to better understand the pathophysiology of cytokine response in leptospirosis.

Leptospirosis is an invasive infectious and systemic inflammatory disease

Pathogenic Leptospira species are the causative agents of leptospirosis, a world-spreading zoonotic infectious disease. The pathogens possess a powerful invasiveness by invading human body through mucosal/skin barriers, rapid entry into bloodstream to cause septicemia, diffusion from bloodstream into internal organs and tissues to cause aggravation of disease, and discharge from urine through renal tubules to form natural infectious sources. Leptospirosis patients present severe inflammatory symptoms such as high fever, myalgia and lymphadenectasis. Hemorrhage and jaundice are the pathological features of this disease. Previous studies revealed that some outer membrane proteins of Leptospira interrogans, the most important pathogenic Leptospira species, acted as adherence factors to binding to receptor molecules (fibronectin, laminin and collagens) in extracellular matrix of host cells. Collagenase, metallopeptidases and endoflagellum contributed to the invasiveness of L. interrogans. Except for lipopolysaccharide, multiple hemolysins of L. interrogans displayed a powerful ability to induce pro-inflammatory cytokines and hepatocyte apoptosis. vWA and platelet activating factor acetylhydrolase-like proteins from L. interrogans could induce severe pulmonary hemorrhage in mice. L. interrogans utilized cellular endocytic recycling and vesicular transport systems for intracellular migration and transcellular transport. All the research achievements are helpful for further understanding the virulence of pathogenic Leptospira species and pathogenesis of leptospirosis.

Elevated levels of IL-8 in fatal leptospirosis

Leptospirosis causes a wide range of clinical outcomes, including organ failure and death. Early treatment significantly increases the chances of cure. Interleukin-8 (IL-8) is a chemoattractant cytokine for neutrophil and is associated with multiple organ failure. Research has indicated IL-8 to be raised in severe and fatal cases of leptospirosis, but its suitability as a prognostic biomarker has yet to be confirmed. This study aimed to evaluate the significance of IL-8 with the clinical outcomes of leptospirosis patients. Plasma IL-8 was measured in fifty-two samples from hospitalized patients and nineteen healthy controls. The comparisons were made between mild, severe-survived and fatal groups identified by clinical or laboratory findings. IL-8 was significantly higher in fatal (p = 0.01) compared to mild cases. IL-8 was also significantly higher in fatal (p = 0.02) when compared to survived cases of leptospirosis. IL-8 levels in the plasma of fatal leptospirosis cases were significantly elevated compared to survived cases and may serve as a potential prognostic biomarker in determining the possible outcome of leptospirosis patients.

Raised levels of Il-6, Il-17a, and Il-22 in fatal leptospirosis

Clinical manifestations of leptospirosis range from mild, common cold-like illness, to a life-threatening condition. The host immune response has been hypothesized to play a major role in leptospirosis outcome. Increased levels of inflammatory mediators, such as cytokines, may promote tissue damage that lead to increased disease severity. The question is whether cytokines levels may predict the outcome of leptospirosis and guide patient management. This study aimed to assess the association between Th1-, Th2-, and Th17-related cytokines with the clinical outcome of patients with leptospirosis. Different cytokine levels were measured in fifty-two plasma samples of hospitalized patients diagnosed with leptospirosis in Malaysia (January 2016-December 2017). Patients were divided into two separate categories: survived (n = 40) and fatal outcome (n = 12). Nineteen plasma samples from healthy individuals were obtained as controls. Cytokine quantification was performed using Simple Plex™ assays from ProteinSimple (San Jose, CA, USA). Measurements were done in triplicate and statistical analysis was performed using GraphPad software and SPSS v20. IL-6 (p = 0.033), IL-17A (p = 0.022), and IL-22 (p = 0.046) were significantly elevated in fatal cases. IL-17A concentration (OR 1.115; 95% CI 1.010-1.231) appeared to be an independent predictor of fatality of leptospirosis. Significantly higher levels of TNF-α (p ≤ 0.0001), IL-6 (p ≤ 0.0001), IL-10 (p ≤ 0.0001), IL-12 (p ≤ 0.0001), IL17A (p ≤ 0.0001), and IL-18 (p ≤ 0.0001) were observed among leptospirosis patients in comparison with healthy controls. Our study shows that certain cytokine levels may serve as possible prognostic biomarkers in leptospirosis patients.

Interaction of Leptospira with the Innate Immune System

Innate immunity encompasses immediate host responses that detect and respond to microbes. Besides recognition by the complement system (see the chapter by A. Barbosa, this volume), innate immunity concerns cellular responses. These are triggered through recognition of conserved microbial components (called MAMPs) by pattern recognition receptors (PRRs), leading, through secretion of cytokines, antimicrobial peptides, and immune mediators, to cellular recruitment and phagocytosis. Leptospira spp. are successful zoonotic pathogenic bacteria that obviously overcome the immune system of their hosts. The first part of this chapter summarizes what is known about leptospires recognition and interaction with phagocytes and other innate immune cells, and the second part describes specific interactions of leptospiral MAMPs with PRRs from the TLR and NLR families. On the one hand, pathogenic leptospires appear to escape macrophage and neutrophil phagocytosis. On the other hand, studies about PRR sensing of leptospires remain very limited, but suggest that pathogenic leptospires escape some of the PRRs in a host-specific manner, due to peculiar cell wall specificities or post-translational modifications that may impair their recognition. Further studies are necessary to clarify the mechanisms and consequences of leptospiral escape on phagocytic functions and hopefully give clues to potential therapeutic strategies aimed at restoring the defective activation of PRRs by pathogenic Leptospira spp.

Leptospirosis in the elderly: the role of age as a predictor of poor outcomes in hospitalized patients

Background: The aim of this study was to investigate factors associated with poor outcomes among elderly hospitalized patients with leptospirosis. Methods: This is a retrospective cohort study with leptospirosis patients admitted to three tertiary hospitals in Fortaleza, Brazil, from January 1985 to July 2017. Patients were divided into two groups: elderly (age ≥60 years) and young (age <60 years). A comparison of demographical, clinical and laboratory data, treatment and outcomes was executed in order to investigate differences between groups. Results: A total of 507 hospitalized patients were included, with mean age 38 ± 15 years. Elderly group presented lower incidence of myalgia, vomiting, and dyspnea, as well as, higher medium systolic blood pressure. Elderly also manifested higher frequency of AKI (85.9 vs. 74.7%, p = 0.05), hemodialysis requirement (54.7 vs. 37.0%, p = 0.007) and death (32.8 vs. 12.2%, p < 0.001). In multivariate analysis, age ≥60 years was a predictor of hemodialysis requirement (p = 0.008, OR = 2.049, 95% CI = 1.207-3.477) and death (p < 0.001, OR = 3.520, 95% CI = 1.940-6.386). Conclusion: Leptospirosis in the elderly is associated with less hemodynamic impairment and higher frequency of AKI. Advanced age was also a predictor of poor outcomes, such as hemodialysis requirement and death, mostly due to kidney involvement.

Do the Th17 Cells Play a Role in the Pathogenesis of Leptospirosis?

Objectives

The aim of this study was to determine the level of five different pro- and anti-inflammatory cytokines to study the inflammatory response of leptospirosis.

Materials and methods

The serum cytokine levels of IL-10, IL-17A, IL-21, IL-23, and TNF-α were investigated in 57 patients with leptospirosis and 12 healthy controls using a commercially available ELISA kit (Mabtech, Sweden). Statistical analysis was done using Graphpad Prism.

Results

Elevation of serum IL-10 and IL-17A levels and significant elevation of serum IL-21 (p=0.002), IL-23 (p=0.002), and TNF-α (p=0.039) were observed among leptospirosis patients compared to the healthy control group. The two major complications observed among these patients were renal failure and liver involvement. Renal failure was significantly associated with elevation of IL-21 and IL-23, while patients with liver involvement had a significant elevation of IL-21, IL-23, and TNF-α.

Conclusion

Elevation of IL-17A together with the significant elevation of IL-21 and IL-23 suggests a possible involvement of Th17 cells in the immunopathogenesis of leptospirosis.

Leptospirosis Pathophysiology: Into the Storm of Cytokines

Leptospirosis is a neglected tropical zoonosis caused by pathogenic spirochetes of the genus Leptospira. Infected reservoir animals, typically mice and rats, are asymptomatic, carry the pathogen in their renal tubules, and shed pathogenic spirochetes in their urine, contaminating the environment. Humans are accidental hosts of pathogenic Leptospira. Most human infections are mild or asymptomatic. However, 10% of human leptospirosis cases develop into severe forms, including high leptospiremia, multi-organ injuries, and a dramatically increased mortality rate, which can relate to a sepsis-like phenotype. During infection, the triggering of the inflammatory response, especially through the production of cytokines, is essential for the early elimination of pathogens. However, uncontrolled cytokine production can result in a cytokine storm process, followed by a state of immunoparalysis, which can lead to sepsis and associated organ failures. In this review, the involvement of cytokine storm and subsequent immunoparalysis in the development of severe leptospirosis in susceptible hosts will be discussed. The potential contribution of major pro-inflammatory cytokines in the development of tissue lesions and systemic inflammatory response, as well as the role of anti-inflammatory cytokines in contributing to the onset of a deleterious immunosuppressive cascade will also be examined. Data from studies comparing susceptible and resistant mouse models will be included. Lastly, a concise discussion on the use of cytokines for therapeutic purposes or as biomarkers of leptospirosis severity will be provided.

Effect of Antimicrobial Agents on Inflammatory Cytokines in Acute Leptospirosis

The aim of this study was to assess the inflammatory cytokine response and possible association with antimicrobial treatment with penicillin, ceftriaxone, and doxycycline in acute leptospirosis. In the early acute stage, interleukin-10 (IL-10) levels were higher in mild cases than in severe cases (P = 0.01). IL-6 and IL-8 levels were low in patients who received >5 antimicrobial doses (P < 0.01). IL-8 levels were negatively correlated with the number of ceftriaxone doses administered (r = -0.315; P = 0.031). Further studies are needed to evaluate the possible downregulation of proinflammatory cytokines by ceftriaxone in leptospirosis.

Leptospirosis in ICU: A Retrospective Study of 134 Consecutive Admissions

OBJECTIVES

Leptospirosis causes reversible multiple organ failure, and its mortality remains high. The aim of this study was to determine the mortality rate of leptospirosis in an ICU offering all types of organ support available nowadays and to compare it with mortality in bacterial sepsis.

DESIGN

Retrospective, descriptive, and single-center cohort study.

SETTINGS

The largest ICU of Reunion Island (Indian Ocean) in a teaching hospital.

PATIENTS

Consecutive patients hospitalized in ICU for leptospirosis from January 2004 to January 2015.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We report 134 cases of patients with leptospirosis hospitalized in ICU. The median age was 40 years (interquartile range, 30-52 yr), with a Simplified Acute Physiology Score II of 38 (27-50) and a Sequential Organ Failure Assessment score of 10 (8-12). Forty-one patients (31%) required mechanical ventilation and 76 (56%) required renal replacement therapy. The door-to-renal replacement therapy time was 0 (0-1) day after admission with a median urea of 25 mmol/L (17-32 mmol/L). Five patients required extracorporeal membrane oxygenation. The mortality rate was 6.0% (95% CI, 2.6-11.4). Among patients hospitalized for sepsis, the standardized mortality ratio of patients with leptospirosis with regards to Simplified Acute Physiology Score II was dramatically low: 0.40 (95% CI, 0.17 - 0.79).

CONCLUSIONS

The mortality of severe leptospirosis is lower than for other bacterial infection, provided modern resuscitation techniques are available. Prompt organ support ensures very low mortality rates despite high severity scores.

Leptospirosis in human: Biomarkers in host immune responses

Leptospirosis remains one of the most widespread zoonotic diseases caused by spirochetes of the genus Leptospira, which accounts for high morbidity and mortality globally. Leptospiral infections are often found in tropical and subtropical regions, with people exposed to contaminated environments or animal reservoirs are at high risk of getting the infection. Leptospirosis has a wide range of clinical manifestations with non-specific signs and symptoms and often misdiagnosed with other acute febrile illnesses at early stage of infection. Despite being one of the leading causes of zoonotic morbidity worldwide, there is still a gap between pathogenesis and human immune responses during leptospiral infection. It still remains obscure whether the severity of the infection is caused by the pathogenic properties of the Leptospira itself, or it is a consequence of imbalance host immune factors. Hence, in this review, we seek to summarize the past and present milestone findings on the biomarkers of host immune response aspects during human leptospiral infection, including cytokine and other immune mediators. A profound understanding of the interlink between virulence factors and host immune responses during human leptospirosis is imperative to identify potential biomarkers for diagnostic and prognostic applications as well as designing novel immunotherapeutic strategies in future.

Major Neutrophilia Observed in Acute Phase of Human Leptospirosis Is Not Associated with Increased Expression of Granulocyte Cell Activation Markers

It has long been known that pathogenic Leptospira can mobilize the immune system but the specific contribution of neutrophils to control the infectious challenge remains to be clarified. We herein analyzed the phenotype of circulating neutrophils of patients with leptospirosis and healthy controls for the expression of toll-like receptor (TLR) type 2 (TLR2, to sense the leptospiral LPS) and several activation markers: interleukin 8 chemokine receptor CD182 (CXCR2), CD11b of the integrin/opsonin complement receptor type 3 (CR3) and CD15 (ligand of the selectin). The plasmatic level of the main CD182 ligand, interleukin 8 (CXCL8), was measured by ELISA. Hospitalized leptospirosis cases showed marked neutrophilia, particularly in the most severe cases. Interestingly, TLR2 was significantly increased in leptospirosis but identical levels of CD182 and CD11b were detected when compared to controls. CD15 was significantly decreased on neutrophils in leptospirosis but returned to normal within 1 month. Basal levels of IL-8 were measured in control subjects and were not increased in leptospirosis cases at the initial stage of the disease. In conclusion, we observed that neutrophils failed to regulate the expression of several of the receptors involved in cell activation and recruitment. This study further emphasizes the paradigm that neutrophils may be impaired in their overall capacity to thwart bacterial infection in leptospirosis patients.

Cytokine levels as biomarkers for leptospirosis patients

Inflammatory mediators were suggested to be biomarkers for prediction of disease severity. In this study, we investigated the levels of IL-6, IL-8, IL-10 and TNF-α in leptospirosis patients with mild or severe illnesses. Sera samples were divided into two groups. The OI group and NOI groups included sera from patients with and without organ involvement, respectively. Each group consisted of 20 pairs of sera. Twenty-five sera from healthy individuals were included as controls. Cytokine levels were compared. Although IL-6, IL-8 and IL-10 levels in acute sera from the OI group were significantly higher than NOI group, only IL-8 level was significantly higher in the OI group when cytokine levels in convalescent sera were compared. TNF-α, an inflammatory cytokine widely studied in leptospirosis was not significantly different between two groups of patients. Our data suggested that IL-6, IL-8 and IL-10 were involved in disease severity. However, time of specimen collection could affect the significant levels of cytokines especially as biomarkers for monitoring disease severity.