To investigate the link between the genomic landscape of cancer cells and immune microenvironment in tumor tissues, we characterized somatic mutations and tumor-infiltrating lymphocytes (TILs) in malignant pleural mesothelioma (MPM), including mutation/neoantigen load, spatial heterogeneity of somatic mutations of cancer cells and TILs (T-cell receptor b (TCRb) repertoire), and expression profiles of immunerelated genes using specimens of three different tumor sites (anterior, posterior, and diaphragm) obtained from six MPM patients. Integrated analysis identified the distinct patterns of somatic mutations and the immune microenvironment signatures both intratumorally and interindividually. MPM cases showed intratumoral heterogeneity in somatic mutations with unique TCRb clonotypes of TILs that were restricted to each tumor site, suggesting the presence of a neoantigen-related immune response. Correlation analyses showed that higher neoantigen load was significantly correlated with stronger clonal expansion of TILs (p D 0.048) and a higher expression level of an immune-associated cytolytic factor (PRF1 (p D 0.0041) in tumor tissues), suggesting that high neoantigen loads in tumor cells might promote expansion of functional tumor-specific T cells in the tumor bed. Our results collectively indicate that MPM tumors constitute a diverse heterogeneity in both the genomic landscape and immune microenvironment, and that mutation/neoantigen load may affect the immune microenvironment in MPM tissues.

Purpose African American colorectal cancer (CRC) patients have worse survival outcomes than Caucasian patients. To determine if differences exist in the molecular mechanisms driving CRC between African Americans and Caucasians, we characterized patient tumors from a single institution by assessing genetic alterations involved in CRC progression and response to treatment. Experimental Design We retrospectively examined 448 African Americans and Caucasians diagnosed with CRC at The University of Chicago Medical Center between 1992 and 2002. Microsatellite instability (MSI) status was determined by genotyping the BAT25, BAT26, BAT40, D5S346, and BAX loci. Mutations in KRAS codons 12 and 13 and BRAF codon 600 were identified by direct sequencing. MSI and detected mutations were correlated with clinicopathological features. Results Overall, no difference existed in MSI or BRAF mutation frequencies between African Americans and Caucasians. However, African Americans with microsatellite stable (MSS)/MSI-low (MSI-L) tumors had a higher proportion of KRAS mutations than Caucasians (34% v. 23%, p=0.048) that was isolated to proximal colon cancers and primarily driven by mutations in codon 13. There was no racial/ethnic difference in receipt of chemotherapy, but African Americans with MSS/MSI-L tumors had a 73% increased risk of death over Caucasians that could not be explained by known prognostic factors. Conclusions The significantly higher risk of death among African Americans with MSS/MSI-L tumors may be related to differences in the distribution of factors influencing response to standard therapies. These data underscore the need for further research into the molecular mechanisms driving CRC progression in underserved and understudied populations.

Maternal embryonic leucine zipper kinase (MELK), that plays a critical role in maintenance of cancer stem cells (CSCs), is predominantly expressed in various types of human cancer including small cell lung cancer (SCLC). SCLC usually acquires resistance to anti-cancer drugs and portends dismal prognosis. We have delineated roles of MELK in development/progression of SCLC and examined anti-tumor efficacy of OTS167, a highly potent MELK inhibitor, against SCLC. MELK expression was highly upregulated in both SCLC cell lines and primary tumors. siRNA-mediated MELK knockdown induced significant growth inhibition in SCLC cell lines. Concordantly, treatment with OTS167 exhibited strong cytotoxicity against eleven SCLC cell lines with IC50 of < 10 nM. As similar to siRNA knockdown, OTS167 treatment induced cytokinetic defects with intercellular bridges, and in some cell lines we observed formation of neuronal protrusions accompanied with increase of a neuronal differentiation marker (CD56), indicating that the compound induced differentiation of cancer cells to neuron-like cells. Furthermore, the MELK inhibition decreased its downstream FOXM1 activity and Akt expression in SCLC cells, and led to apoptotic cell death. OTS167 appeared to be more effective to CSCs as measured by the sphere formation assay, thus MELK inhibition might become a promising treatment modality for SCLC.

We have identified new malaria vaccine candidates through the combination of bioinformatics prediction of stable protein domains in the Plasmodium falciparum genome, chemical synthesis of polypeptides, in vitro biological functional assays, and association of an antigen-specific antibody response with protection against clinical malaria.Within the predicted open reading frame of P. falciparum hypothetical protein PFF0165c, several segments with low hydrophobic amino acid content, which are likely to be intrinsically unstructured, were identified. The synthetic peptide corresponding to one such segment (P27A) was well recognized by sera and peripheral blood mononuclear cells of adults living in different regions where malaria is endemic. High antibody titers were induced in different strains of mice and in rabbits immunized with the polypeptide formulated with different adjuvants. These antibodies recognized native epitopes in P. falciparum-infected erythrocytes, formed distinct bands in Western blots, and were inhibitory in an in vitro antibody-dependent cellular inhibition parasite-growth assay. The immunological properties of P27A, together with its low polymorphism and association with clinical protection from malaria in humans, warrant its further development as a malaria vaccine candidate.

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A new strategy for the rapid identification of new malaria antigens based on protein structural motifs was previously described. We identified and evaluated the malaria vaccine potential of fragments of several malaria antigens containing α-helical coiled coil protein motifs. By taking advantage of the relatively short size of these structural fragments, we constructed different poly-epitopes in which 3 or 4 of these segments were joined together via a non-immunogenic linker. Only peptides that are targets of human antibodies with anti-parasite in vitro biological activities were incorporated. One of the constructs, P181, was well recognized by sera and peripheral blood mononuclear cells (PBMC) of adults living in malaria-endemic areas. Affinity purified antigen-specific human antibodies and sera from P181-immunized mice recognised native proteins on malaria-infected erythrocytes in both immunofluorescence and western blot assays. In addition, specific antibodies inhibited parasite development in an antibody dependent cellular inhibition (ADCI) assay. Naturally induced antigen-specific human antibodies were at high titers and associated with clinical protection from malaria in longitudinal follow-up studies in Senegal.

It is widely accepted that antibody responses against the human parasitic pathogen Plasmodium falciparum protect the host from the rigors of severe malaria and death. However, there is a continuing need for the development of in vitro correlate assays of immune protection. To this end, the capacity of human monoclonal and polyclonal antibodies in eliciting phagocytosis and parasite growth inhibition via Fc␥ receptor-dependent mechanisms was explored. In examining the extent to which sequence diversity in merozoite surface protein 2 (MSP2) results in the evasion of antibody responses, an unexpectedly high level of heterologous function was measured for allele-specific human antibodies. The dependence on Fc␥ receptors for opsonic phagocytosis and monocyte-mediated antibody-dependent parasite inhibition was demonstrated by the mutation of the Fc domain of monoclonal antibodies against both MSP2 and a novel vaccine candidate, peptide 27 from the gene PFF0165c. The described flow cytometry-based functional assays are expected to be useful for assessing immunity in naturally infected and vaccinated individuals and for prioritizing among blood-stage antigens for inclusion in blood-stage vaccines.Merozoite surface protein 2 (MSP2) is a leading Plasmodium falciparum vaccine candidate. Antibody responses to MSP2 have been associated with protection from malaria in humans (1,11,37,43,50,53) and afford protection in mouse models (35,46). However, extreme sequence diversity in MSP2 is considered an obstacle for vaccine design. Hundreds of alleles encoding MSP2 are classified into two main allelic families represented by the 3D7 and FC27/D10 MSP2 sequences (15,28,49,57). The coexistence of parasites bearing the dimorphic alleles at similar frequencies in globally disparate locations indicates their maintenance by selective pressures (9). Given that MSP2 is a blood-stage antigen, it is considered likely that sequence diversification may be driven by the host immune response by allele-specific antibodies. Consistent with this hypothesis, vaccine recipients in the Combination B phase IIb vaccine trial, whose humoral responses against the MSP2-3D7 allele were boosted, were rendered more susceptible than the placebo controls to parasitization with heterologous FC27-type parasites (16,19). Early studies showed that mouse monoclonal antibodies (MAbs) that discriminated between heterologous parasites affected homologous in vitro growth inhibition (7, 13). Curiously, there is scant evidence of the inability of allele-specific MAbs to inhibit heterologous parasites in vitro (45).Like other P. falciparum antigens, MSP2 antibody responses are skewed to cytophilic (IgG1 and IgG3) isotypes (37,43,50,53,54), which have been positively associated with protection from malaria (4,11,21,37,44,50,54). These isotypes bind via their Fc domain to Fc␥ receptors, thereby eliciting cellular immune responses of the innate immune system. Antibody opsonization of P. falciparum-infected erythrocytes and merozoites enhances their phagocytosis (6,12,22,30,3...

Background Healthcare workers (HCWs) are at the front line of the ongoing coronavirus pandemic. Comprehensively evaluating SARS-CoV-2 seroprevalence among HCWs in a large healthcare system could help identify the impact that epidemiological factors and presence of symptoms have on immune response to the infection over time. Aim To determine the seroprevalence of SARS-CoV-2 specific antibodies among healthcare workers (HCWs), to identify associated epidemiological factors and to study antibody kinetics. Methods We completed a longitudinal evaluation of the seroprevalence and epidemiology of SARS-CoV-2 specific antibodies in approximately 30,000 HCWs in the largest healthcare system in the State of Connecticut. Findings The baseline prevalence of SARS-CoV-2 antibody among 6,863 HCWs was 6.3% (95% CI: 5.7%-6.9%) and was highest among patient care support (16.7%), medical assistants (9.1%), and nurses (8.2%) and lower for physicians (3.8%) and advanced practice providers (4.5%). Seroprevalence was significantly higher among African Americans (OR 3.26 compared to Caucasians, 95% CI 1.77-5.99), in participants with at least one COVID symptom (OR 3.00, 95% CI 1.92-4.68), and in those reporting prior quarantine (OR 3.83, 95% CI 2.57-5.70). No symptoms were reported in 24% of the seropositive participants. Among the 47% who returned for a follow-up serology test, the seroreversion rate was 39.5% and the seroconversion rate was 2.2%. The incidence of reinfection in the seropositive group was zero. Conclusion Although there is a decline in the IgG antibody signal over time, 60.5% of the seropositive HCWs maintain their seroconversion status after a median time of 5.5 months.