Preclinical development of kinetin as a safe error-prone SARS-CoV-2 antiviral able to attenuate virus-induced inflammation.

Orally available antivirals against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are necessary because of the continuous circulation of new variants that challenge immunized individuals. Because severe COVID-19 is a virus-triggered immune and inflammatory dysfunction, molecules endowed with both antiviral and anti-inflammatory activity are highly desirable. We identified here that kinetin (MB-905) inhibits the in vitro replication of SARS-CoV-2 in human hepatic and pulmonary cell lines. On infected monocytes, MB-905 reduced virus replication, IL-6 and TNFα levels. MB-905 is converted into its triphosphate nucleotide to inhibit viral RNA synthesis and induce error-prone virus replication. Coinhibition of SARS-CoV-2 exonuclease, a proofreading enzyme that corrects erroneously incorporated nucleotides during viral RNA replication, potentiated the inhibitory effect of MB-905. MB-905 shows good oral absorption, its metabolites are stable, achieving long-lasting plasma and lung concentrations, and this drug is not mutagenic nor cardiotoxic in acute and chronic treatments. SARS-CoV-2-infected hACE-mice and hamsters treated with MB-905 show decreased viral replication, lung necrosis, hemorrhage and inflammation. Because kinetin is clinically investigated for a rare genetic disease at regimens beyond the predicted concentrations of antiviral/anti-inflammatory inhibition, our investigation suggests the opportunity for the rapid clinical development of a new antiviral substance for the treatment of COVID-19.

Isolation of Echimidine and Its C-7 Isomers from Echium plantagineum L. and Their Hepatotoxic Effect on Rat Hepatocytes.

Echimidine is the main pyrrolizidine alkaloid of Echium plantagineum L., a plant domesticated in many countries. Because of echimidine's toxicity, this alkaloid has become a target of the European Food Safety Authority regulations, especially in regard to honey contamination. In this study, we determined by NMR spectroscopy that the main HPLC peak purified from zinc reduced plant extract with an MS [M + H]+ signal at m/z 398 corresponding to echimidine (1), and in fact also represents an isomeric echihumiline (2). A third isomer present in the smallest amount and barely resolved by HPLC from co-eluting (1) and (2) was identified as hydroxymyoscorpine (3). Before the zinc reduction, alkaloids (1) and (2) were present mostly (90%) in the form of an N-oxide, which formed a single peak in HPLC. This is the first report of finding echihumiline and hydroxymyoscorpine in E. plantagineum. Retroanalysis of our samples of E. plantagineum collected in New Zealand, Argentina and the USA confirmed similar co-occurrence of the three isomeric alkaloids. In rat hepatocyte primary culture cells, the alkaloids at 3 to 300 µg/mL caused concentration-dependent inhibition of hepatocyte viability with mean IC50 values ranging from 9.26 to 14.14 µg/mL. Our discovery revealed that under standard HPLC acidic conditions, echimidine co-elutes with its isomers, echihumiline and to a lesser degree with hydroxymyoscorpine, obscuring real alkaloidal composition, which may have implications for human toxicity.

Monitoring of Peripheral Blood Leukocytes and Plasma Samples: A Pilot Study to Examine Treatment Response to Leflunomide in Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a painful inflammatory disease of the joints which affects a considerable proportion of the world population, mostly women. If not adequately treated, RA patients can become permanently disabled. Importantly, not all the patients respond to the available anti-rheumatic therapies, which also present diverse side effects. In this context, monitoring of treatment response is pivotal to avoid unnecessary side effects and costs towards an ineffective therapy. Herein, we performed a pilot study to investigate the potential use of flow cytometry and attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy as measures to identify responders and non-responders to leflunomide, a disease-modifying drug used in the treatment of RA patients. The evaluation of peripheral blood CD62L+ polymorphonuclear cell numbers and ATR-FTIR vibrational modes in plasma were able to discriminate responders to leflunomide (LFN) three-months after therapy has started. Overall, the results indicate that both flow cytometry and ATR-FTIR can potentially be employed as additional measures to monitor early treatment response to LFN in RA patients.

Bradykinin Receptors Play a Critical Role in the Chronic Post-ischaemia Pain Model.

Complex regional pain syndrome type-I (CRPS-I) is a chronic painful condition resulting from trauma. Bradykinin (BK) is an important inflammatory mediator required in acute and chronic pain response. The objective of this study was to evaluate the association between BK receptors (B1 and B2) and chronic post-ischaemia pain (CPIP) development in mice, a widely accepted CRPS-I model. We assessed mechanical and cold allodynia, and paw oedema in male and female Swiss mice exposed to the CPIP model. Upon induction, the animals were treated with BKR antagonists (HOE-140 and DALBK); BKR agonists (Tyr-BK and DABK); antisense oligonucleotides targeting B1 and B2 and captopril by different routes in the model (7, 14 and 21 days post-induction). Here, we demonstrated that treatment with BKR antagonists, by intraperitoneal (i.p.), intraplantar (i.pl.), and intrathecal (i.t.) routes, mitigated CPIP-induced mechanical allodynia and oedematogenic response, but not cold allodynia. On the other hand, i.pl. administration of BKR agonists exacerbated pain response. Moreover, a single treatment with captopril significantly reversed the anti-allodynic effect of BKR antagonists. In turn, the inhibition of BKRs gene expression in the spinal cord inhibited the nociceptive behaviour in the 14th post-induction. The results of the present study suggest the participation of BKRs in the development and maintenance of chronic pain associated with the CPIP model, possibly linking them to CRPS-I pathogenesis.

Taxane-induced neurotoxicity: Pathophysiology and therapeutic perspectives.

Taxane-derived drugs are antineoplastic agents used for the treatment of highly common malignancies. Paclitaxel and docetaxel are the most commonly used taxanes; however, other drugs and formulations have been used, such as cabazitaxel and nab-paclitaxel. Taxane treatment is associated with neurotoxicity, a well-known and relevant side effect, very prevalent amongst patients undergoing chemotherapy. Painful peripheral neuropathy is the most dose-limiting side effect of taxanes, affecting up to 97% of paclitaxel-treated patients. Central neurotoxicity is an emerging side effect of taxanes and it is characterized by cognitive impairment and encephalopathy. Besides impairing compliance to chemotherapy treatment, taxane-induced neurotoxicity (TIN) can adversely affect the patient's life quality on a long-term basis. Despite the clinical relevance, not many reviews have comprehensively addressed taxane-induced neurotoxicity when they are used therapeutically. This article provides an up-to-date review on the pathophysiology of TIN and the novel potential therapies to prevent or treat this side effect.

B1 and B2 kinin receptor blockade improves psoriasis-like disease.

BACKGROUND AND PURPOSE: The entire kallikrein-kinin system is present in the skin, and it is thought to exert a relevant role in cutaneous diseases, including psoriasis. The present study was designed to evaluate the relevance of kinin receptors in the development and progression of a model of psoriasis in mice. EXPERIMENTAL APPROACH: The effects of kinin B1 and B2 receptor knockout and of kinin receptor antagonists (SSR240612C or FR173657) were assessed in a model of psoriasis induced by imiquimod in C57BL/6 mice. Severity of psoriasis was assessed by histological and immunohistochemical assays of skin, along with objective scores based on the clinical psoriasis area and severity index. KEY RESULTS: Both kinin receptors were up-regulated following 6 days of imiquimod treatment. Kinin B1 and B2 receptor deficiency and the use of selective antagonists show morphological and histological improvement of the psoriasis hallmarks. This protective effect was associated with a decrease in undifferentiated and proliferating keratinocytes, decreased cellularity (neutrophils, macrophages, and CD4+ T lymphocytes), reduced γδ T cells, and lower accumulation of IL-17. The lack of B2 receptors resulted in reduced CD8+ T cells in the psoriatic skin. Relevantly, blocking kinin receptors reflected the improvement of psoriasis disease in the well-being behaviour of the mice. CONCLUSIONS AND IMPLICATIONS: Kinins exerted critical roles in imiquimod-induced psoriasis. Both B1 and B2 kinin receptors exacerbated the disease, influencing keratinocyte proliferation and immunopathology. Antagonists of one or even both kinin receptors might constitute a new strategy for the clinical treatment of psoriasis.

Corrigendum: Cinnamaldehyde Inhibits Staphylococcus aureus Virulence Factors and Protects against Infection in a Galleria mellonella Model.

[This corrects the article DOI: 10.3389/fmicb.2016.02052.].

A new series of acetohydroxamates shows in vitro and in vivo anticancer activity against melanoma.

Cancer treatment is challenging, mainly due to high levels of drug toxicity and the resistance of tumours to chemotherapy. Hydroxamic acid derivatives have recently aroused attention due to their potential to treat malignancies. In the present study, we sought to investigate the anticancer effects of a new series of synthetic acetohydroxamates. The in vitro cytotoxic and antiproliferative effects of 11 synthetic acetohydroxamates were evaluated against the melanoma cell line A375. Apoptosis, cell cycle, and autophagy assays were employed to elucidate the cell death pathways induced by the compounds. The in vivo pharmacokinetic profiles of the most promising compounds were determined in CD-1 mice, while the in vivo antitumour efficacies were evaluated using the A375 melanoma xenograft model in nude mice. MTT assays revealed that all compounds presented concentration-dependent cytotoxicity against the A375 cell line. AKS 61 produced the most favourable antiproliferative activity according to the sulphorhodamine B and clonogenic assays. AKS 61 treatment resulted in decreased mitochondrial membrane potential and increased apoptosis and autophagy in the A375 cell line. However, AKS 61 failed to prevent in vivo tumour growth in a melanoma xenograft, whereas compound AKS 7 was able to inhibit tumour growth when administered orally. These in vivo findings may be explained by a more favourable pharmacokinetic profile presented by AKS 7 when compared to AKS 61. Taken together, these results suggest that acetohydroxamates have potential anticancer effects and will guide future optimisation of these molecules to allow for further non-clinical development.

The role of natural products in modern drug discovery.

The global medicine market is about 1.1 trillion US dollars. About 35 percent of medicines have originated from natural products. Brazil presents the largest biodiversity in the world, with more than 50,000 species of higher plants. However, few innovative products have been developed in Brazil from active constituents derived from the Brazilian biodiversity. Scientific evidences on plants and venoms have been internationally published by Brazilian scientists over the last 4 decades; but few examples of innovative products are commercially available. Few examples include the anti-hypertensive drug captopril first identified in the venom of the Brazilian viper Bothrops jararaca by Professor Sergio Ferreira; and some phytotherapeutic agents such as Acheflan®, Syntocalmy® and Melagrião® produced by standardized plant extracts with scientific proof of safety, efficacy and quality. Still, only Acheflan® and Melagrião® are obtained from native Brazilian plants. Several issues contribute to the lack of innovative products from the Brazilian biodiversity, but in my opinion, the most challenging ones are i) the lack of specific regulations to allow researchers and companies to access biodiversity for the purposes of scientific and technological innovation; and ii) the absence of a long-term government program to support research and innovation in this field.

Topical Application of Cinnamaldehyde Promotes Faster Healing of Skin Wounds Infected with Pseudomonas aeruginosa.

Wound healing can be delayed following colonization and infection with the common bacterium Pseudomonas aeruginosa. While multiple therapies are used for their treatment, these are ineffective, expensive, and labour-intensive. Thus, there is an enormous unmet need for the treatment of infected wounds. Cinnamaldehyde, the major component of cinnamon oil, is well known for its antimicrobial properties. Herein, we investigated the effects of sub-inhibitory concentrations of cinnamaldehyde in the virulence of P. aeruginosa. We also assessed its healing potential in P. aeruginosa-infected mouse skin wounds and the mechanisms involved in this response. Sub-inhibitory concentrations of cinnamaldehyde reduced P. aeruginosa metabolic rate and its ability to form biofilm and to cause haemolysis. Daily topical application of cinnamaldehyde on P. aeruginosa-infected skin wounds reduced tissue bacterial load and promoted faster healing. Lower interleukin-17 (IL-17), vascular endothelial growth factor (VEGF) and nitric oxide levels were detected in cinnamaldehyde-treated wound samples. Blockage of transient receptor potential ankyrin 1, the pharmacological target of cinnamaldehyde, abrogated its healing activity and partially reversed the inhibitory actions of this compound on VEGF and IL-17 generation. We suggest that topical application of sub-inhibitory concentrations of cinnamaldehyde may represent an interesting approach to improve the healing of P. aeruginosa-infected skin wounds.

Correction to: The kinin B1 and B2 receptors and TNFR1/p55 axis on neuropathic pain in the mouse brachial plexus.

Unfortunately, the Fig. 7 was wrongly downloaded in the original publication.

Spinal blockage of CXCL1 and its receptor CXCR2 inhibits paclitaxel-induced peripheral neuropathy in mice.

Painful peripheral neuropathy is the most dose-limiting side effect of paclitaxel (PTX), a widely used anti-cancer drug to treat solid tumours. The understanding of the mechanisms involved in this side effect is crucial to the development of new therapeutic approaches. CXCL1 chemokine and its receptor CXCR2 have been pointed as promising targets to treat chronic pain. Herein, we sought to evaluate the possible involvement of CXCL1 and CXCR2 in the pathogenesis of PTX-induced neuropathic pain in mice. PTX treatment led to increased levels of CXCL1 in both dorsal root ganglion and spinal cord samples. Systemic treatment with the anti-CXCL1 antibody (10 µg/kg, i.v.) or the selective CXCR2 antagonist (SB225002, 3 mg/kg, i.p.) had minor effect on PTX-induced mechanical hypersensitivity. On the other hand, the intrathecal (i.t.) treatment with anti-CXCL1 (1 ng/site) or SB225002 (10 µg/site) consistently inhibited the nociceptive responses of PTX-treated mice. Similar results were obtained by inhibiting the PI3Kγ enzyme a downstream pathway of CXCL1/CXCR2 signalling with either the selective AS605240 (5 µg/site, i.t.) or the non-selective wortmannin PI3K inhibitor (0.4 µg/site, i.t.). Overall, the data indicates that the up-regulation of CXCL1 is important for the development and maintenance of PTX-induced neuropathic pain in mice. Therefore, the spinal blockage of CXCL1/CXCR2 signalling might be a new innovative therapeutic approach to treat this clinical side effect of PTX.

The kinin B1 and B2 receptors and TNFR1/p55 axis on neuropathic pain in the mouse brachial plexus.

Tumour necrosis factor (TNF) and kinins have been associated with neuropathic pain-like behaviour in numerous animal models. However, the way that they interact to cause neuron sensitisation remains unclear. This study assessed the interaction of kinin receptors and TNF receptor TNFR1/p55 in mechanical hypersensitivity induced by an intraneural (i.n.) injection of rm-TNF into the lower trunk of brachial plexus in mice. The i.n. injection of rm-TNF reduced the mechanical withdrawal threshold of the right forepaw from the 3rd to the 10th day after the injection, indicating that TNF1/p55 displays a critical role in the onset of TNF-elicited neuropathic pain. The connection between TNF1/p55 and kinin B1 and B2 receptors (B1R and B2R) was confirmed using both knockout mice and mRNAs quantification in the injected nerve, DRG and spinal cord. The treatment with the B2R antagonist HOE 140 or with B1R antagonist des-Arg9-Leu8-BK reduced both BK- and DABK-induced hypersensitivity. The experiments using kinin receptor antagonists and CPM inhibitor (thiorphan) suggest that BK does not only activate B2R as an orthosteric agonist, but also seems to be converted into DABK that consequently activates B1R. These results indicate a connection between TNF and the kinin system, suggesting a relevant role for B1R and B2R in the process of sensitisation of the central nervous systems by the cross talk between the receptor and CPM after i.n. injection of rm-TNF.

Transient Receptor Potential Canonical Channels 4 and 5 Mediate Escherichia coli-Derived Thioredoxin Effects in Lipopolysaccharide-Injected Mice.

Thioredoxin plays an essential role in bacterial antioxidant machinery and virulence; however, its regulatory actions in the host are less well understood. Reduced human Trx activates transient receptor potential canonical 5 (TRPC5) in inflammation, but there is no evidence of whether these receptors mediate bacterial thioredoxin effects in the host. Importantly, TRPC5 can form functional complexes with other subunits such as TRPC4. Herein, E. coli-derived thioredoxin induced mortality in lipopolysaccharide- (LPS-) injected mice, accompanied by reduction of leukocyte accumulation, regulation of cytokine release into the peritoneum, and impairment of peritoneal macrophage-mediated phagocytosis. Dual TRPC4/TRPC5 blockade by ML204 increased mortality and hypothermia in thioredoxin-treated LPS mice but preserved macrophage's ability to phagocytose. TRPC5 deletion did not alter body temperature but promoted additional accumulation of peritoneal leukocytes and inflammatory mediator release in thioredoxin-administered LPS mice. Thioredoxin diminished macrophage-mediated phagocytosis in wild-type but not TRPC5 knockout animals. TRPC5 ablation did not affect LPS-induced responses. However, ML204 caused mortality associated with exacerbated hypothermia and decreased peritoneal leukocyte numbers and cytokines in LPS-injected mice. These results suggest that bacterial thioredoxin effects under LPS stimuli are mediated by TRPC4 and TRPC5, shedding light on the additional mechanisms of bacterial virulence and on the pathophysiological roles of these receptors.

Kinin Receptors Sensitize TRPV4 Channel and Induce Mechanical Hyperalgesia: Relevance to Paclitaxel-Induced Peripheral Neuropathy in Mice.

Kinin B1 (B1R) and B2 receptors (B2R) and the transient receptor potential vanilloid 4 (TRPV4) channel are known to play a critical role in the peripheral neuropathy induced by paclitaxel (PTX) in rodents. However, the downstream pathways activated by kinin receptors as well as the sensitizers of the TRPV4 channel involved in this process remain unknown. Herein, we investigated whether kinins sensitize TRPV4 channels in order to maintain PTX-induced peripheral neuropathy in mice. The mechanical hyperalgesia induced by bradykinin (BK, a B2R agonist) or des-Arg9-BK (DABK, a B1R agonist) was inhibited by the selective TRPV4 antagonist HC-067047. Additionally, BK was able to sensitize TRPV4, thus contributing to mechanical hyperalgesia. This response was dependent on phospholipase C/protein kinase C (PKC) activation. The selective kinin B1R (des-Arg9-[Leu8]-bradykinin) and B2R (HOE 140) antagonists reduced the mechanical hyperalgesia induced by PTX, with efficacies and time response profiles similar to those observed for the TRPV4 antagonist (HC-067047). Additionally, both kinin receptor antagonists inhibited the overt nociception induced by hypotonic solution in PTX-injected animals. The same animals presented lower PKCε levels in skin and dorsal root ganglion samples. The selective PKCε inhibitor (εV1-2) reduced the hypotonicity-induced overt nociception in PTX-treated mice with the same magnitude observed for the kinin receptor antagonists. These findings suggest that B1R or B2R agonists sensitize TRPV4 channels to induce mechanical hyperalgesia in mice. This mechanism of interaction may contribute to PTX-induced peripheral neuropathy through the activation of PKCε. We suggest these targets represent new opportunities for the development of effective analgesics to treat chronic pain.

The relevance of kalikrein-kinin system via activation of B2 receptor in LPS-induced fever in rats.

PURPOSE: This study evaluated the involvement of endogenous kallikrein-kinin system and the bradykinin (BK) B1 and B2 receptors on LPS- induced fever and the POA cells involved in this response. MATERIAL AND METHODS: Male Wistar rats received either i.v. (1 mg/kg), i.c.v. (20 nmol) or i.h. (2 nmol) injections of icatibant (B2 receptor antagonist) 30 or 60 min, respectively, before the stimuli. DALBK (B1 receptor antagonist) was given either 15min before BK (i.c.v.) or 30 min before LPS (i.v.). Captopril (5 mg/kg, sc.,) was given 1 h prior LPS or BK. Concentrations of BK and total kininogenon CSF, plasma and tissue kallikrein were evaluated. Rectal temperatures (rT) were assessed by telethermometry. Ca++ signaling in POA cells was performed in rat pup brain tissue microcultures. RESULTS: Icatibant reduced LPS fever while, captopril exacerbated that response, an effect abolished by icatibant. Icatibant (i.h.) reduced fever to BK (i.h.) but not that induced by LPS (i.v.). BK increased intracellular calcium concentration in neurons and astrocytes. LPS increased levels of bradykinin, tissue kallikrein and total kininogen. BK (i.c.v.) increased rT and decreased tail skin temperature. Captopril potentiated BK-induced fever an effect abolished by icatibant. DALBK reduced the fever induced by BK. BK (i.c.v.) increased the CSF PGE2concentration. Effect abolished by indomethacin (i.p.). CONCLUSIONS: LPS activates endogenous kalikrein-kinin system leading to production of BK, which by acting on B2-receptors of POA cells causes prostaglandin synthesis that in turn produces fever. Thus, a kinin B2-receptor antagonist that enters into the brain could constitute a new and interesting strategy to treat fever.

Antiallodynic effect of ß-caryophyllene on paclitaxel-induced peripheral neuropathy in mice.

Painful peripheral neuropathy is a common side effect of paclitaxel (PTX). The use of analgesics is an important component for management of PTX-induced peripheral neuropathy (PINP). However, currently employed analgesics have several side effects and are poorly effective. ß-caryophyllene (BCP), a dietary selective CB2 agonist, has shown analgesic effect in neuropathic pain models, but its role in chemotherapy-induced neuropathic pain has not yet been investigated. Herein, we used the mouse model of PINP to show the therapeutic effects of BCP in this neuropathy. Male Swiss mice receiving PTX (2 mg kg-1, ip, four alternate days) were treated with BCP (25 mg kg-1, po, twice a day) either during or after PTX administration. Some groups were also pretreated with AM630 (CB2 antagonist, 3 mg kg-1, ip) or AM251 (CB1 antagonist, 1 mg kg-1, ip). Spinal cord samples were collected in different time points to perform immunohistochemical analysis. BCP attenuated the established mechanical allodynia induced by PTX (p < 0.0001) in a CB2-dependent manner. Of note, when given concomitantly with PTX, BCP was able to attenuate the development of PINP (p < 0.0001). Spinal cord immunohistochemistry revealed that preventive treatment with BCP reduced p38 MAPK and NF-κB activation, as well as the increased Iba-1 and IL-1ß immunoreactivity promoted by PTX. Our findings show that BCP effectively attenuated PINP, possibly through CB2-activation in the CNS and posterior inhibition of p38 MAPK/NF-κB activation and cytokine release. Taken together, our results suggest that BCP could be used to attenuate the establishment and/or treat PINP.

Preclinical safety evaluation of IQG-607 in rats: Acute and repeated dose toxicity studies.

In the present study, we evaluated the safety and the possible toxic effects of IQG-607 after acute and 90-day repeated administrations in rats. Single oral administration of IQG-607 (300 or 2000 mg/kg) on female rats did not result in any mortality. No gross lesions were observed in the animals at necropsy. Ninety-day administration test resulted in 20% of deaths, in both male and female rats administered with the highest dose of IQG-607, 300 mg/kg. Repeated administration of the IQG 607 (25, 100 and 300 mg/kg) did not result in any significant body mass alteration, or changes in food and water consumption. The most important clinical sign observed was salivation in both sexes. Importantly, long-term treatment with IQG-607 did not induce alterations in any hematological (for both sex) and serum biochemical (for female) parameters evaluated, even at the highest dose tested. Treatment of male rats with 100 or 300 mg/kg of IQG-607 decreased total cholesterol levels, while animals treated with 100 mg/kg also presented reduction on triglyceride levels. Of note, no treatment induced significant histopathological alterations in tissues of all organs and glands analyzed, even in that group that received the highest dose of IQG-607.

Transient Receptor Potential Ankyrin 1 Channel Expression on Peripheral Blood Leukocytes from Rheumatoid Arthritic Patients and Correlation with Pain and Disability.

Patients with rheumatoid arthritis (RA) suffer from pain and joint disability. The transient receptor potential ankyrin 1 (TRPA1) channel expressed on sensory neurones and non-neuronal cells mediates pain transduction and inflammation and it has been implicated in RA. However, there is little information on the contribution of TRPA1 for human disease. Here, we investigated the expression of TRPA1 on peripheral blood leukocytes and the circulating levels of its endogenous activators 4-hydroxynonenal (4-HNE) and hydrogen peroxide (H2O2) in RA patients treated or not with the anti-rheumatic leflunomide (LFN) or the anti-TNFα adalimumab (ADA). We also assessed whether TRPA1 expression correlates with joint pain and disability, in addition to the immune changes in RA. TRPA1 expression on peripheral blood leukocytes correlated with pain severity and disability. TRPA1 levels on these cells were associated with the numbers of polymorphonuclear and the activation of CD14+ cells. No correlations were found between the lymphocyte population and TRPA1 expression, pain or disability. Patients recently diagnosed with RA expressed increased levels of TRPA1 on their leukocytes whilst treatment with either LFN or ADA down-regulated this receptor probably by reducing the numbers of polymorphonuclears and the activation of CD14+ cells. We suggest that the activation levels of CD14+ cells, the numbers of PMNs in the peripheral blood and the expression of TRPA1 on peripheral blood leukocytes correlate with RA progression, affecting joint pain sensitivity and loss of function.