B- and T-Cell Responses After SARS-CoV-2 Vaccination in Patients With Multiple Sclerosis Receiving Disease Modifying Therapies: Immunological Patterns and Clinical Implications

BackgroundVaccination campaign to contrast the spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has raised the issue of vaccine immunogenicity in special populations such as people with multiple sclerosis (PwMS) on highly effective disease modifying treatments (DMTs). While humoral responses to SARS-CoV-2 mRNA vaccines have been well characterized in the general population and in PwMS, very little is known about cell-mediated responses in conferring protection from SARS-CoV-2 infection and severe coronavirus disease-2019 (COVID-19).MethodsPwMS on ocrelizumab, fingolimod or natalizumab, vaccinated with two doses of mRNABNT162b2 (Comirnaty®) vaccine were enrolled. Anti-Spike (S) and anti-Nucleoprotein (N) antibody titers, IFN-gamma production upon S and N peptide libraries stimulation, peripheral blood lymphocyte absolute counts were assessed after at least 1 month and within 4 months from vaccine second dose administration. A group of age and sex matched healthy donors (HD) were included as reference group. Statistical analysis was performed using GraphPad Prism 8.2.1.ResultsThirty PwMS and 9 HDs were enrolled. All the patients were negative for anti-N antibody detection, nor reported previous symptoms of COVID-19. Peripheral blood lymphocyte counts were assessed in PwMS showing: (i) reduction of circulating B-lymphocytes in PwMS on ocrelizumab; (ii) reduction of peripheral blood B- and T-lymphocyte absolute counts in PwMS on fingolimod and (iii) normal B- and T-lymphocyte absolute counts with an increase in circulating CD16+CD56+ NK-cells in PwMS on natalizumab. Three patterns of immunological responses were identified in PwMS. In patients on ocrelizumab, anti-S antibody were lacking or reduced, while T-cell responses were normal. In patients on fingolimod both anti-S titers and T-cell mediated responses were impaired. In patients on natalizumab both anti-S titers and T-cell responses were present and comparable to those observed in HD.ConclusionsThe evaluation of T-cell responses, anti-S titers and peripheral blood lymphocyte absolute count in PwMS on DMTs can help to better characterize the immunological response after SARS-CoV-2 vaccination. The evaluation of T-cell responses in longitudinal cohorts of PwMS will help to clarify their protective role in preventing SARS-CoV-2 infection and severe COVID-19. The correlation between DMT treatment and immunological responses to SARS-CoV-2 vaccines could help to better evaluate vaccination strategies in PwMS.

Differential recognition and cytokine induction by the peptidorhamnomannan from Sporothrix brasiliensis and S. schenckii

Sporotrichosis is a deep mycosis caused by dimorphic species of the genus Sporothrix, with differences in pathogenicity between S. schenckii and S. brasiliensis species. Recently, it was discovered that the cell wall peptidorhamnomannan (PRM) of Sporothrix spp . is a pathogen associated molecular pattern (PAMP). Interestingly, S. brasiliensis PRM has additional unknown rhamnose residues. We hypothesize that the structural differences of Sporothrix spp PRMs impact the host's immune response and may explain the severity of sporotrichosis caused by S. brasiliensis. Here we demonstrate that S. brasiliensis yeasts and its PRM (S.b PRM) induced a strong inflammatory response in human PBMCs, with high production of TNF-α, IL-6 and IL-1β and induction of T-helper cytokines IFN-γ, IL-17 and IL-22. In contrast, S. schenckii yeasts and its PRM induced higher concentrations of interleukin-1 receptor antagonist (IL-1Ra), which resulted in low production of T-helper cytokines such as IL-17 and IL-22. CR3 and dectin-1 were required for cytokine induction by both PRMs, while TLR2 and TLR4 were required for the response of S.s PRM and S.b PRM, respectively. IL-1β and IL-1α production induced by S. brasiliensis yeasts and S.b PRM were dependent on inflammasome and caspase-1 activation. S. schenckii and S.s PRM were able to induce IL-1β independent of ROS. In conclusion, these findings improve our understanding of the pathogenesis of Sporothrix spp. by reporting differences of immunological responses induced by S. schenckii and S. brasiliensis. The study also opens the gateway for novel treatment strategies targeting local inflammation and tissue destruction induced by S. brasiliensis infection through IL-1 inhibition.

Cellular and Humoral Responses to SARS-CoV-2 Vaccination in Immunosuppressed Patients

Objective: SARS-CoV-2 vaccinations have demonstrated vaccine-immunogenicity in healthy volunteers, however, efficacy in immunosuppressed patients is less well characterised. There is an urgent need to address the impact of immunosuppression on vaccine immunogenicity. Methods: Serological, T-cell ELISpot, cytokines and immunophenotyping assays were used to assess vaccine responses (either BNT162b2 mRNA or ChAdOx1 nCoV-19) in double-vaccinated patients receiving immunosuppression for renal transplants or haematological malignancies (n=13). Immunological responses in immunosuppressed patients (VACC-IS) were compared to immunocompetent vaccinated (VACC-IC, n=12), unvaccinated (UNVACC, n=11) and infection-naïve unvaccinated (HC, n=3) cohorts. All participants, except HC, had prior COVID-19 infection. Results: T-cell responses were identical between VACC-IS and VACC-IC (92%) to spike-peptide (S) stimulation. UNVACC had the highest T-cell non-responders (n=3), whereas VACC-IC and VACC-IS both had one T-cell non-responder. No significant differences in humoral responses were observed between VACC-IC and VACC-IS, with 92% (12/13) of VACC-IS patients demonstrating seropositivity. One VACC-IS failed to seroconvert, however had detectable T-cell responses. All VACC-IC participants were seropositive for anti-spike antibodies. VACC-IS and VACC-IC participants elicited strong Th1 cytokine response with immunodominance towards S-peptide. Differences in T-cell immunophenotyping were seen between VACC-IS and VACC-IC, with lower CD8+ activation and T-effector memory phenotype observed in VACC-IS. Conclusion: SARS-CoV-2 vaccines are immunogenic in patients receiving immunosuppressive therapy, with responses comparable to vaccinated immunocompetent participants. Lower humoral responses were seen in patients treated with B-cell depleting therapeutics, but with preserved T-cell responses. We suggest further work to correlate both protective immunity and longevity of these responses in both healthy and immunosuppressed patients.

Expression of OLFM4 and Lysozyme During Necrotizing Enterocolitis and Volvulus in Newborns: a Comparative Observational Research Study

Background: In neonatal patients with necrotizing enterocolitis (NEC) and volvulus the inflammatory response is mediated by a plurality of different proteins. The proteins olfactomedin 4 (OLFM4) and lysozyme (LYZ) are part of the intestinal mucosal defense and especially OLFM4 has rarely been evaluated in neonatal gastrointestinal diseases. The aim of this study was to compare the expression levels of OLFM4 and lysozyme during NEC and volvulus in neonates. Methods: Intestinal tissues of patients with NEC and patients with volvulus were examined using immunohistochemical staining of OLFM4 and lysozyme of formalin-fixed and paraffin-embedded sections of resected tissue. Staining-positive tissues were semi-quantitatively scored from 0 (no staining), 1 (weak staining), 2 (moderate staining) to 3 (highly intense staining) by two individual investigators.Results: Both applied antibodies against OLFM4 showed different staining patterns with higher staining intensity of the antibody OLFM4 (D1E4M). OLFM4 (median score of the antibody OLFM4 (D1E4M): 3.0) and lysozyme (median score: 3.0) are highly expressed in intestinal and immune cells during NEC. The expression of OLFM4 and lysozyme in tissue with intestinal volvulus was also observable (median score of the antibody OLFM4 (D1E4M): 1.25) and median score of the antibody against LYZ: 2.0), but lower levels could be seen in comparison to tissue with NEC (p=0.033 and p=0.037, respectively).Conclusions: Both proteins, OLFM4 and lysozyme, may play a role in the pathogenesis of NEC and volvulus in neonatal patients, but the exact mechanisms of OLFM4 and lysozyme function and their role in immunological responses have not yet been resolved. These observations add new insights as basis for further large-scale population research.

Emerging Role of PD-1/PD-L1 Inhibitors in Chronic Liver Diseases

Programmed cell death protein 1 (PD-1)/PD-ligand (L)1, the immune checkpoint inhibitors have emerged as a promising strategy for the treatment of various diseases including chronic liver diseases (CLDs) such as hepatitis, liver injury and hepatocellular carcinoma (HCC). The role of PD-1/PD-L1 has been widely inspected in the treatment of viral hepatitis and HCC. PD-1 is known to play a crucial role in inhibiting immunological responses and stimulates self-tolerance by regulating the T-cell activity. Further, it promotes apoptosis of antigen-specific T-cells while preventing apoptosis of Treg cells. PD-L1 is a trans-membrane protein which is recognized as a co-inhibitory factor of immunological responses. Both, PD-1 and PD-L1 function together to downregulate the proliferation of PD-1 positive cells, suppress the expression of cytokines and stimulate apoptosis. Owing to the importance of PD-1/PD-L1 signaling, this review aims to summarize the potential of PD-1/PD-L1 inhibitors in CLDs along with toxicities associated with them. We have enlisted some of the important roles of PD-1/PD-L1 in CLDs, the clinically approved products and the pipelines of drugs under clinical evaluation.

Innate Receptors Expression by Lung Nociceptors: Impact on COVID-19 and Aging

The lungs are constantly exposed to non-sterile air which carries harmful threats, such as particles and pathogens. Nonetheless, this organ is equipped with fast and efficient mechanisms to eliminate these threats from the airways as well as prevent pathogen invasion. The respiratory tract is densely innervated by sensory neurons, also known as nociceptors, which are responsible for the detection of external stimuli and initiation of physiological and immunological responses. Furthermore, expression of functional innate receptors by nociceptors have been reported; however, the influence of these receptors to the lung function and local immune response is poorly described. The COVID-19 pandemic has shown the importance of coordinated and competent pulmonary immunity for the prevention of pathogen spread as well as prevention of excessive tissue injury. New findings suggest that lung nociceptors can be a target of SARS-CoV-2 infection; what remains unclear is whether innate receptor trigger sensory neuron activation during SARS-CoV-2 infection and what is the relevance for the outcomes. Moreover, elderly individuals often present with respiratory, neurological and immunological dysfunction. Whether aging in the context of sensory nerve function and innate receptors contributes to the disorders of these systems is currently unknown. Here we discuss the expression of innate receptors by nociceptors, particularly in the lungs, and the possible impact of their activation on pulmonary immunity. We then demonstrate recent evidence that suggests lung sensory neurons as reservoirs for SARS-CoV-2 and possible viral recognition via innate receptors. Lastly, we explore the mechanisms by which lung nociceptors might contribute to disturbance in respiratory and immunological responses during the aging process.

The Multifaceted Effects of Gut Microbiota on the Immune System of the Intestinal Mucosa

The gut microbiota has diverse microbial components, including bacteria, viruses, and fungi. The interaction between gut microbiome components and immune responses has been studied extensively over the last decade. Several studies have reported the potential role of the gut microbiome in maintaining gut homeostasis and the development of disease. The commensal microbiome can preserve the integrity of the mucosal barrier by acting on the host immune system. Contrastingly, dysbiosis-induced inflammation can lead to the initiation and progression of several diseases through inflammatory processes and oxidative stress. In this review, we describe the multifaceted effects of the gut microbiota on several diseases from the perspective of mucosal immunological responses.